Publications
Stay up to date with our research by following us on Google Scholar, ORCID, Scopus, ResearcherID, ResearchGate, and Twitter.
2022
Gao, Mei-Yan; Sensharma, Debobroto; Bezrukov, Andrey A.; Andaloussi, Yassin H.; Darwish, Shaza; Deng, Chenghua; Vandichel, Matthias; Zhang, Jian; Zaworotko, Michael J.
A Robust Molecular Porous Material for C2H2/CO2 Separation Journal Article Forthcoming
In: Small, vol. n/a, no. n/a, pp. 2206945, Forthcoming.
@article{https://doi.org/10.1002/smll.202206945,
title = {A Robust Molecular Porous Material for C2H2/CO2 Separation},
author = {Mei-Yan Gao and Debobroto Sensharma and Andrey A. Bezrukov and Yassin H. Andaloussi and Shaza Darwish and Chenghua Deng and Matthias Vandichel and Jian Zhang and Michael J. Zaworotko},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/smll.202206945},
doi = {https://doi.org/10.1002/smll.202206945},
year = {2022},
date = {2022-12-22},
journal = {Small},
volume = {n/a},
number = {n/a},
pages = {2206945},
abstract = {Abstract A molecular porous material, MPM-2, comprised of cationic [Ni2(AlF6)(pzH)8(H2O)2] and anionic [Ni2Al2F11(pzH)8(H2O)2] complexes that generate a charge-assisted hydrogen-bonded network with pcu topology is reported. The packing in MPM-2 is sustained by multiple interionic hydrogen bonding interactions that afford ultramicroporous channels between dense layers of anionic units. MPM-2 is found to exhibit excellent stability in water (>1 year). Unlike most hydrogen-bonded organic frameworks which typically show poor stability in organic solvents, MPM-2 exhibited excellent stability with respect to various organic solvents for at least two days. MPM-2 is found to be permanently porous with gas sorption isotherms at 298 K revealing a strong affinity for C2H2 over CO2 thanks to a high (ΔQst)AC [Qst (C2H2) − Qst (CO2)] of 13.7 kJ mol−1 at low coverage. Dynamic column breakthrough experiments on MPM-2 demonstrated the separation of C2H2 from a 1:1 C2H2/CO2 mixture at 298 K with effluent CO2 purity of 99.995% and C2H2 purity of >95% after temperature-programmed desorption. C-H···F interactions between C2H2 molecules and F atoms of AlF63− are found to enable high selectivity toward C2H2, as determined by density functional theory simulations.},
keywords = {},
pubstate = {forthcoming},
tppubtype = {article}
}
Huerta-Flores, Ali Margot; Ruiz-Zepeda, Francisco; Eyovge, Cavit; Winczewski, Jedrzej P.; Vandichel, Matthias; Gaberšček, Miran; Boscher, Nicolas D.; Gardeniers, Han J. G. E.; Torres-Martínez, Leticia M.; Susarrey-Arce, Arturo
Enhanced Photocatalytic Hydrogen Evolution from Water Splitting on Ta2O5/SrZrO3 Heterostructures Decorated with CuxO/RuO2 Cocatalysts Journal Article
In: ACS Applied Materials & Interfaces, vol. 14, iss. 28, pp. 31767–31781, 2022, (PMID: 35786845).
@article{doi:10.1021/acsami.2c02520,
title = {Enhanced Photocatalytic Hydrogen Evolution from Water Splitting on Ta2O5/SrZrO3 Heterostructures Decorated with CuxO/RuO2 Cocatalysts},
author = {Ali Margot Huerta-Flores and Francisco Ruiz-Zepeda and Cavit Eyovge and Jedrzej P. Winczewski and Matthias Vandichel and Miran Gaberšček and Nicolas D. Boscher and Han J. G. E. Gardeniers and Leticia M. Torres-Martínez and Arturo Susarrey-Arce},
url = {https://doi.org/10.1021/acsami.2c02520},
doi = {10.1021/acsami.2c02520},
year = {2022},
date = {2022-07-12},
urldate = {2022-07-12},
journal = {ACS Applied Materials & Interfaces},
volume = {14},
issue = {28},
pages = {31767–31781},
note = {PMID: 35786845},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Schmidt, Thorsten O.; Ngoipala, Apinya; Arevalo, Ryan L.; Watzele, Sebastian A.; Lipin, Raju; Kluge, Regina M.; Hou, Shujin; Haid, Richard W.; Senyshyn, Anatoliy; Gubanova, Elena L.; Bandarenka, Aliaksandr S.; Vandichel, Matthias
Elucidation of Structure–Activity Relations in Proton Electroreduction at Pd Surfaces: Theoretical and Experimental Study Journal Article
In: Small, vol. n/a, no. 18, pp. 2202410, 2022.
@article{https://doi.org/10.1002/smll.202202410,
title = {Elucidation of Structure–Activity Relations in Proton Electroreduction at Pd Surfaces: Theoretical and Experimental Study},
author = {Thorsten O. Schmidt and Apinya Ngoipala and Ryan L. Arevalo and Sebastian A. Watzele and Raju Lipin and Regina M. Kluge and Shujin Hou and Richard W. Haid and Anatoliy Senyshyn and Elena L. Gubanova and Aliaksandr S. Bandarenka and Matthias Vandichel},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/smll.202202410},
doi = {https://doi.org/10.1002/smll.202202410},
year = {2022},
date = {2022-06-20},
urldate = {2022-06-20},
journal = {Small},
volume = {n/a},
number = {18},
pages = {2202410},
abstract = {Abstract The structure–activity relationship is a cornerstone topic in catalysis, which lays the foundation for the design and functionalization of catalytic materials. Of particular interest is the catalysis of the hydrogen evolution reaction (HER) by palladium (Pd), which is envisioned to play a major role in realizing a hydrogen-based economy. Interestingly, experimentalists observed excess heat generation in such systems, which became known as the debated “cold fusion” phenomenon. Despite the considerable attention on this report, more fundamental knowledge, such as the impact of the formation of bulk Pd hydrides on the nature of active sites and the HER activity, remains largely unexplored. In this work, classical electrochemical experiments performed on model Pd(hkl) surfaces, “noise” electrochemical scanning tunneling microscopy (n-EC-STM), and density functional theory are combined to elucidate the nature of active sites for the HER. Results reveal an activity trend following Pd(111) > Pd(110) > Pd(100) and that the formation of subsurface hydride layers causes morphological changes and strain, which affect the HER activity and the nature of active sites. These findings provide significant insights into the role of subsurface hydride formation on the structure–activity relations toward the design of efficient Pd-based nanocatalysts for the HER.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Rodriguez-Olguin, M. A.; Flox, C.; Ponce-Pérez, R.; Lipin, R.; Ruiz-Zepeda, F.; Winczewski, J. P.; Kallio, T.; Vandichel, M.; Guerrero-Sánchez, J.; Gardeniers, J. G. E.; Takeuchi, N.; Susarrey-Arce, A.
Chlorine in NiO promotes electroreduction of CO2 to formate Journal Article
In: Applied Materials Today, vol. 28, pp. 101528, 2022, ISSN: 2352-9407.
@article{RODRIGUEZOLGUIN2022101528,
title = {Chlorine in NiO promotes electroreduction of CO2 to formate},
author = {M. A. Rodriguez-Olguin and C. Flox and R. Ponce-Pérez and R. Lipin and F. Ruiz-Zepeda and J. P. Winczewski and T. Kallio and M. Vandichel and J. Guerrero-Sánchez and J. G. E. Gardeniers and N. Takeuchi and A. Susarrey-Arce},
url = {https://www.sciencedirect.com/science/article/pii/S2352940722001639},
doi = {https://doi.org/10.1016/j.apmt.2022.101528},
issn = {2352-9407},
year = {2022},
date = {2022-05-23},
urldate = {2022-05-23},
journal = {Applied Materials Today},
volume = {28},
pages = {101528},
abstract = {We report the exceptional finding that NiO, a known electroactive catalyst for the reduction of CO2 to CO, can be tuned to become an active electrocatalyst for CO2 reduction to formate when chlorine is synthetically incorporated into NiO. The CO2 reduction reaction (CO2RR) is carried out on chlorine-containing NiO octahedral particles made by a solid-state synthesis method yielding a Faradaic efficiency (FE) of 70 % for formate production at -0.8 V vs. RHE with a partial current density of 14.7 mA/cm2. XPS confirms the presence of Ni3+ and Ni2+ species, indicating the existence of uncoordinated Ni. The Ni3+/Ni2+ ratio increases with the Cl concentrations on NiO. Cl concentrations are also confirmed with STEM-EDX. DFT modeling provides insights into the thermodynamic stability and CO2RR mechanism over the Cl-containing NiO surface. It is suggested that Cl can occupy the defective sites created by oxygen vacancies on the NiO model with Cl (O-alpha+Cl). The surface Pourbaix diagrams constructed from DFT indicate the preferred surface terminations favorable at the operating conditions for the CO2RR, which closely agrees with the experimental findings. The O-alpha+Cl has been found to promote CO2RR to formate. Our results create new possibilities in the development of earth-abundant electrocatalysts for selective CO2RR},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Ali, Farhan S. M.; Arevalo, Ryan Lacdao; Vandichel, Matthias; Speck, Florian; Rautama, Eeva-Leena; Jiang, Hua; Sorsa, Olli; Mustonen, Kimmo; Cherevko, Serhiy; Kallio, Tanja
Hydrogen Evolution in Alkaline Medium on Intratube and Surface Decorated PtRu Catalyst Journal Article
In: Applied Catalysis B: Environmental, vol. 315, pp. 121541, 2022, ISSN: 0926-3373.
@article{ALI2022121541,
title = {Hydrogen Evolution in Alkaline Medium on Intratube and Surface Decorated PtRu Catalyst},
author = {Farhan S. M. Ali and Ryan Lacdao Arevalo and Matthias Vandichel and Florian Speck and Eeva-Leena Rautama and Hua Jiang and Olli Sorsa and Kimmo Mustonen and Serhiy Cherevko and Tanja Kallio},
url = {https://www.sciencedirect.com/science/article/pii/S0926337322004829},
doi = {https://doi.org/10.1016/j.apcatb.2022.121541},
issn = {0926-3373},
year = {2022},
date = {2022-05-23},
urldate = {2022-05-23},
journal = {Applied Catalysis B: Environmental},
volume = {315},
pages = {121541},
abstract = {For anion exchange membrane (AEM) electrolysis, challenges include finding an optimal catalyst for hydrogen evolution reaction (HER), as the noble metals are scarce while non-noble metals are inferior. Here, the noble metal amount is reduced in a straightforward solution synthesis which produces Pt-Ru surface nanoparticles and unique intratube nanowires decorated on single walled carbon nanotubes (SWNT). In half-cell tests, 5 wtPtRu-% Pt-Ru SWNT demonstrates stable 10mAcm−2 HER current at 46mV overpotential and outperforms commercial electrocatalysts. When integrated in an AEM electrolyser, a high current density of 500mAcm−2 at a low voltage of 1.72V is achieved with 34µgcm−2 metal loading. First-principles calculations reveal that both the Pt-Ru alloy nanoparticle and intratube nanowires promote near optimal H* binding energy, thereby releasing the H2 faster. Thus, our approach yields an active low metal loading alkaline HER catalyst without sacrificing the performance in an AEM electrolyser.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Nikkhah, Sousa Javan; Vandichel, Matthias
Modeling Polyzwitterion-Based Drug Delivery Platforms: A Perspective of the Current State-of-the-Art and Beyond Journal Article
In: ACS Engineering Au, vol. 2, pp. 274−294, 2022.
@article{nokey,
title = {Modeling Polyzwitterion-Based Drug Delivery Platforms: A Perspective of the Current State-of-the-Art and Beyond},
author = {Sousa Javan Nikkhah and Matthias Vandichel},
doi = {10.1021/acsengineeringau.2c00008},
year = {2022},
date = {2022-05-03},
urldate = {2022-05-03},
journal = {ACS Engineering Au},
volume = {2},
pages = {274−294},
abstract = {Drug delivery platforms are anticipated to have biocompatible and bioinert surfaces. PEGylation of drug carriers is the most approved method since it improves water solubility and colloid stability and decreases the drug vehicles’ interactions with blood components. Although this approach extends their biocompatibility, biorecognition mechanisms prevent them from biodistribution and thus efficient drug transfer. Recent studies have shown (poly)zwitterions to be alternatives for PEG with superior biocompatibility. (Poly)zwitterions are super hydrophilic, mainly stimuli-responsive, easy to functionalize and they display an extremely low protein adsorption and long biodistribution time. These unique characteristics make them already promising candidates as drug delivery carriers. Furthermore, since they have highly dense charged groups with opposite signs, (poly)zwitterions are intensely hydrated under physiological conditions. This exceptional hydration potential makes them ideal for the design of therapeutic vehicles with antifouling capability, i.e., preventing undesired sorption of biologics from the human body in the drug delivery vehicle. Therefore, (poly)zwitterionic materials have been broadly applied in stimuli-responsive “intelligent” drug delivery systems as well as tumor-targeting carriers because of their excellent biocompatibility, low cytotoxicity, insignificant immunogenicity, high stability, and long circulation time. To tailor (poly)zwitterionic drug vehicles, an interpretation of the structural and stimuli-responsive behavior of this type of polymer is essential. To this end, a direct study of molecular-level interactions, orientations, configurations, and physicochemical properties of (poly)zwitterions is required, which can be achieved via molecular modeling, which has become an influential tool for discovering new materials and understanding diverse material phenomena. As the essential bridge between science and engineering, molecular simulations enable the fundamental understanding of the encapsulation and release behavior of intelligent drug-loaded (poly)zwitterion nanoparticles and can help us to systematically design their next generations. When combined with experiments, modeling can make quantitative predictions. This perspective article aims to illustrate key recent developments in (poly)zwitterion-based drug delivery systems. We summarize how to use predictive multiscale molecular modeling techniques to successfully boost the development of intelligent multifunctional (poly)zwitterions-based systems.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Salmanion, Mahya; Kondov, Ivan; Vandichel, Matthias; Aleshkevych, Pavlo; Najafpour, Mohammad Mahdi
Surprisingly Low Reactivity of Layered Manganese Oxide toward Water Oxidation in Fe/Ni-Free Electrolyte under Alkaline Conditions Journal Article
In: Inorganic Chemistry, vol. 61, iss. 4, no. 0, pp. 2292–2306, 2022, (PMID: 35029976).
@article{doi:10.1021/acs.inorgchem.1c03665,
title = {Surprisingly Low Reactivity of Layered Manganese Oxide toward Water Oxidation in Fe/Ni-Free Electrolyte under Alkaline Conditions},
author = {Mahya Salmanion and Ivan Kondov and Matthias Vandichel and Pavlo Aleshkevych and Mohammad Mahdi Najafpour},
url = {https://doi.org/10.1021/acs.inorgchem.1c03665},
doi = {10.1021/acs.inorgchem.1c03665},
year = {2022},
date = {2022-01-14},
urldate = {2022-01-14},
journal = {Inorganic Chemistry},
volume = {61},
number = {0},
issue = {4},
pages = {2292–2306},
abstract = {So far, many studies on the oxygen-evolution reaction (OER) by Mn oxides have been focused on activity; however, the identification of the best performing active site and corresponding catalytic cycles is also of critical importance. Herein, the real intrinsic activity of layered Mn oxide toward OER in Fe/Ni-free KOH is studied for the first time. At pH ≈ 14, the onset of OER for layered Mn oxide in the presence of Fe/Ni-free KOH happens at 1.72 V (vs reversible hydrogen electrode (RHE)). In the presence of Fe ions, a 190 mV decrease in the overpotential of OER was recorded for layered Mn oxide as well as a significant decrease (from 172.8 to 49 mV/decade) in the Tafel slope. Furthermore, we find that both Ni and Fe ions increase OER remarkably in the presence of layered Mn oxide, but that pure layered Mn oxide is not an efficient catalyst for OER without Ni and Fe under alkaline conditions. Thus, pure layered Mn oxide and electrolytes are critical factors in finding the real intrinsic activity of layered Mn oxide for OER. Our results call into question the high efficiency of layered Mn oxides toward OER under alkaline conditions and also elucidate the significant role of Ni and Fe impurities in the electrolyte in the presence of layered Mn oxide toward OER under alkaline conditions. Overall, a computational model supports the conclusions from the experimental structural and electrochemical characterizations. In particular, substitutional doping with Fe decreases the thermodynamic OER overpotential up to 310 mV. Besides, the thermodynamic OER onset potential calculated for the Fe-free structures is higher than 1.7 V (vs RHE) and, thus, not in the stability range of Mn oxides.},
note = {PMID: 35029976},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Sensharma, Debobroto; O'Hearn, Daniel J.; Koochaki, Amin; Bezrukov, Andrey A.; Kumar, Naveen; Wilson, Benjamin H.; Vandichel, Matthias; Zaworotko, Michael J.
The First Sulfate-Pillared Hybrid Ultramicroporous Material, SOFOUR-1-Zn, and Its Acetylene Capture Properties Journal Article
In: Angewandte Chemie International Edition, vol. 61, pp. e202116145, 2022.
@article{https://doi.org/10.1002/anie.202116145,
title = {The First Sulfate-Pillared Hybrid Ultramicroporous Material, SOFOUR-1-Zn, and Its Acetylene Capture Properties},
author = {Debobroto Sensharma and Daniel J. O'Hearn and Amin Koochaki and Andrey A. Bezrukov and Naveen Kumar and Benjamin H. Wilson and Matthias Vandichel and Michael J. Zaworotko},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.202116145},
doi = {https://doi.org/10.1002/anie.202116145},
year = {2022},
date = {2022-01-02},
urldate = {2022-01-02},
journal = {Angewandte Chemie International Edition},
volume = {61},
pages = {e202116145},
abstract = {Abstract Hybrid ultramicroporous materials, HUMs, are comprised of metal cations linked by combinations of inorganic and organic ligands. Their modular nature makes them amenable to crystal engineering studies, which have thus far afforded four HUM platforms (as classified by the inorganic linkers). HUMs are of practical interest because of their benchmark gas separation performance for several industrial gas mixtures. We report herein design and gram-scale synthesis of the prototypal sulfate-linked HUM, the fsc topology coordination network ([Zn(tepb)(SO4)]n), SOFOUR-1-Zn},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Rodriguez-Olguin, M. A.; Atia, H.; Bosco, M.; Aguirre, A.; Eckelt, R.; Asuquo, E. D.; Vandichel, M.; Gardeniers, J. G. E.; Susarrey-Arce, A.
Al2O3 Nanofibers Prepared from Aluminum Di(sec-butoxide)acetoacetic Ester Chelate Exhibits High Surface Area and Acidity Journal Article
In: Journal of Catalysis, vol. 405, pp. 520-533, 2022, ISSN: 0021-9517.
@article{RODRIGUEZOLGUIN2021,
title = {Al2O3 Nanofibers Prepared from Aluminum Di(sec-butoxide)acetoacetic Ester Chelate Exhibits High Surface Area and Acidity},
author = {M. A. Rodriguez-Olguin and H. Atia and M. Bosco and A. Aguirre and R. Eckelt and E. D. Asuquo and M. Vandichel and J. G. E. Gardeniers and A. Susarrey-Arce},
url = {https://www.sciencedirect.com/science/article/pii/S0021951721004796},
doi = {https://doi.org/10.1016/j.jcat.2021.11.019},
issn = {0021-9517},
year = {2022},
date = {2022-01-01},
urldate = {2021-11-22},
journal = {Journal of Catalysis},
volume = {405},
pages = {520-533},
abstract = {Alumina (Al2O3) is a widely used material for catalysis in the chemical industry. Besides a high specific surface area, acid sites on Al2O3 play a crucial role in the chemical transformation of adsorbed molecules, which ultimately react and desorb from the catalyst. This study introduces a synthetic method based on electrospinning to produce Al2O3 nanofibers (ANFs) with acidity and porosity tuned using different aluminum precursor formulations. After electrospinning and heat treatment, the nanofibers form a non-woven network with macropores (∼4 μm). Nanofibers produced from aluminum di(sec-butoxide)acetoacetic ester chelate (ASB) show the highest total acidity of ca. 0.70 µmol/m2 determined with temperature-programmed desorption of ammonia (NH3-TPD) and BET. The nature of the acid site in ASB ANFs is studied in detail with infrared (IR) spectroscopy. Pyridine is used as a molecular probe for the identification of acid sites in ASB. Pyridine showed the presence of Lewis acid sites prominently. Density-functional theory (DFT) is conducted to understand the desorption kinetics of the adsorbed chemical species, such as ammonia (NH3) on crystalline γ-Al2O3. For our analysis, we focused on a mobile approach for chemisorbed and physisorbed NH3. The computational results are compared with NH3-TPD experiments, ultimately utilized to estimate the desorption energy and kinetic desorption parameters. The experiments are found to pair up with our simulation results. We predict that these non-woven structures will find application as a dispersion medium of metallic particles in catalysis.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2021
Kumar, Naveen; Mukherjee, Soumya; Harvey-Reid, Nathan C.; Bezrukov, Andrey A.; Tan, Kui; Martins, Vinicius; Vandichel, Matthias; Pham, Tony; Wyk, Lisa M.; Oyekan, Kolade; Kumar, Amrit; Forrest, Katherine A.; Patil, Komal M.; Barbour, Leonard J.; Space, Brian; Huang, Yining; Kruger, Paul E.; Zaworotko, Michael J.
Breaking the trade-off between selectivity and adsorption capacity for gas separation Journal Article
In: Chem, vol. 7, no. 11, pp. 3085-3098, 2021, ISSN: 2451-9294.
@article{KUMAR20213085,
title = {Breaking the trade-off between selectivity and adsorption capacity for gas separation},
author = {Naveen Kumar and Soumya Mukherjee and Nathan C. Harvey-Reid and Andrey A. Bezrukov and Kui Tan and Vinicius Martins and Matthias Vandichel and Tony Pham and Lisa M. Wyk and Kolade Oyekan and Amrit Kumar and Katherine A. Forrest and Komal M. Patil and Leonard J. Barbour and Brian Space and Yining Huang and Paul E. Kruger and Michael J. Zaworotko},
url = {https://www.sciencedirect.com/science/article/pii/S2451929421003636},
doi = {https://doi.org/10.1016/j.chempr.2021.07.007},
issn = {2451-9294},
year = {2021},
date = {2021-11-11},
urldate = {2021-01-01},
journal = {Chem},
volume = {7},
number = {11},
pages = {3085-3098},
abstract = {Summary The trade-off between selectivity and adsorption capacity with porous materials is a major roadblock to reducing the energy footprint of gas separation technologies. To address this matter, we report herein a systematic crystal engineering study of C2H2 removal from CO2 in a family of hybrid ultramicroporous materials (HUMs). The HUMs are composed of the same organic linker ligand, 4-(3,5-dimethyl-1H-pyrazol-4-yl)pyridine, pypz, three inorganic pillar ligands, and two metal cations, thereby affording six isostructural pcu topology HUMs. All six HUMs exhibited strong binding sites for C2H2 and weaker affinity for CO2. The tuning of pore size and chemistry enabled by crystal engineering resulted in benchmark C2H2/CO2 separation performance. Fixed-bed dynamic column breakthrough experiments for an equimolar (v/v = 1:1) C2H2/CO2 binary gas mixture revealed that one sorbent, SIFSIX-21-Ni, was the first C2H2 selective sorbent that combines exceptional separation selectivity (27.7) with high adsorption capacity (4 mmol·g−1).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abdi, Zahra; Vandichel, Matthias; Sologubenko, Alla S.; Willinger, Marc-Georg; Shen, Jian-Ren; Allakhverdiev, Suleyman I.; Najafpour, Mohammad Mahdi
The importance of identifying the true catalyst when using Randles-Sevcik equation to calculate turnover frequency Journal Article
In: International Journal of Hydrogen Energy, vol. 46, no. 76, pp. 37774-37781, 2021, ISSN: 0360-3199.
@article{ABDI202137774,
title = {The importance of identifying the true catalyst when using Randles-Sevcik equation to calculate turnover frequency},
author = {Zahra Abdi and Matthias Vandichel and Alla S. Sologubenko and Marc-Georg Willinger and Jian-Ren Shen and Suleyman I. Allakhverdiev and Mohammad Mahdi Najafpour},
url = {https://www.sciencedirect.com/science/article/pii/S0360319921035199},
doi = {https://doi.org/10.1016/j.ijhydene.2021.09.039},
issn = {0360-3199},
year = {2021},
date = {2021-09-29},
urldate = {2021-01-01},
journal = {International Journal of Hydrogen Energy},
volume = {46},
number = {76},
pages = {37774-37781},
abstract = {Water splitting will become important to store excess renewable electrical energy into hydrogen. Although the oxygen-evolution reaction (OER) by water oxidation is a critical reaction for water splitting, further investigations are needed to find the details of the OER mechanism for various electrocatalysts. More in particular for homogeneous electrocatalysts, the Randles-Sevcik equation has been extensively applied to determine the turnover frequency (TOF). Herein, using vitamin B12 as a case study, we show that the dynamical deposition/dissolution of the heterogeneous catalyst during OER makes the Randles-Sevcik equation too complicated to be used for calculating the TOF. Indeed, the conventionally applied post-characterization methods do not provide sufficient accuracy to prove the homogeneity of OER mechanisms; thus, using the Randles-Sevcik equation to calculate the TOF is not necessarily correct.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Äntypov, Dmytro; Au, Vonika Ka-Man; Cooley, Isabel; Coudert, François-Xavier; D’Alessandro, Deanna M.; Li, Qiaowei; Schroder, Martin; Suyetin, Mikhail; Vandichel, Matthias; Yang, Sihai; Zaworotko, Michael; Besley, Elena"
Theory and modelling: general discussion Journal Article
In: Faraday Discuss., vol. 231, pp. 258-265, 2021.
@article{D1FD90057A,
title = {Theory and modelling: general discussion},
author = {Dmytro Äntypov and Vonika Ka-Man Au and Isabel Cooley and François-Xavier Coudert and Deanna M. D’Alessandro and Qiaowei Li and Martin Schroder and Mikhail Suyetin and Matthias Vandichel and Sihai Yang and Michael Zaworotko and Elena" Besley},
url = {http://dx.doi.org/10.1039/D1FD90057A},
doi = {10.1039/D1FD90057A},
year = {2021},
date = {2021-09-29},
urldate = {2021-01-01},
journal = {Faraday Discuss.},
volume = {231},
pages = {258-265},
publisher = {The Royal Society of Chemistry},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Sharma, Shivani; Mukherjee, Soumya; Desai, Aamod V; Vandichel, Matthias; Dam, Gourab K; Jadhav, Ashwini; Kociok-Köhn, Gabriele; Zaworotko, Michael J; Ghosh, Sujit K
Efficient Capture of Trace Acetylene by an Ultramicroporous Metal–Organic Framework with Purine Binding Sites Journal Article
In: Chemistry of Materials, vol. 33, no. 14, pp. 5800-5808, 2021.
@article{doi:10.1021/acs.chemmater.1c01723,
title = {Efficient Capture of Trace Acetylene by an Ultramicroporous Metal–Organic Framework with Purine Binding Sites},
author = {Shivani Sharma and Soumya Mukherjee and Aamod V Desai and Matthias Vandichel and Gourab K Dam and Ashwini Jadhav and Gabriele Kociok-Köhn and Michael J Zaworotko and Sujit K Ghosh},
url = {https://doi.org/10.1021/acs.chemmater.1c01723},
doi = {10.1021/acs.chemmater.1c01723},
year = {2021},
date = {2021-07-09},
urldate = {2021-07-09},
journal = {Chemistry of Materials},
volume = {33},
number = {14},
pages = {5800-5808},
abstract = {Efficient separation of acetylene (C2H2) from its byproducts, especially CO2, is difficult because of their similar physicochemical properties, including molecular dimensions and boiling point. Herein, we demonstrate trace C2H2 removal from C2H2/CO2 mixtures enabled by a new ultramicroporous metal–organic framework (MOF) adsorbent, IPM-101, which features an optimal pore size of 4 Å (close to the kinetic diameter of C2H2, 3.3 Å) and one-dimensional channels lined by Lewis basic purine groups. Single-component gas adsorption isotherms revealed a clear affinity toward C2H2 versus CO2 at low pressures with a substantial C2H2 uptake of 0.9 mmol g–1 at 3000 ppm and 298 K. Dynamic column breakthrough experiments revealed separation of C2H2 from 1:1 and 1:99 v/v C2H2/CO2 mixtures. IPM-101 exhibits one of the highest dynamic separation selectivity (αAC) values yet reported, 22.5 for 1:1 C2H2/CO2. Computational simulations indicated that the purine moiety was key to the strong C2H2 selectivity thanks to C2H2 selective N···HC≡CH interactions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abdi, Zahra; Balaghi, Esmael S; Sologubenko, Alla S; Willinger, Marc-Georg; Vandichel, Matthias; Shen, Jian-Ren; Allakhverdiev, Suleyman I; Patzke, Greta R; Najafpour, Mohammad Mahdi
Understanding the Dynamics of Molecular Water Oxidation Catalysts with Liquid-Phase Transmission Electron Microscopy: The Case of Vitamin B12 Journal Article
In: ACS Sustainable Chemistry & Engineering, vol. 9, no. 28, pp. 9494-9505, 2021.
@article{doi:10.1021/acssuschemeng.1c03539,
title = {Understanding the Dynamics of Molecular Water Oxidation Catalysts with Liquid-Phase Transmission Electron Microscopy: The Case of Vitamin B12},
author = {Zahra Abdi and Esmael S Balaghi and Alla S Sologubenko and Marc-Georg Willinger and Matthias Vandichel and Jian-Ren Shen and Suleyman I Allakhverdiev and Greta R Patzke and Mohammad Mahdi Najafpour},
url = {https://doi.org/10.1021/acssuschemeng.1c03539},
doi = {10.1021/acssuschemeng.1c03539},
year = {2021},
date = {2021-07-07},
journal = {ACS Sustainable Chemistry & Engineering},
volume = {9},
number = {28},
pages = {9494-9505},
abstract = {Cobalt compounds are intensely explored as efficient catalysts for the oxygen evolution reaction (OER). Since vitamin B12 is a soluble cobalt compound with high enzymatic activity, evaluating its OER activity is of relevance for biomimetic catalyst research. In this work, the temporal evolution of a homogenous vitamin B12 catalyst in the early stages of OER was investigated by an advanced combination of in situ electrochemical liquid transmission electron microscopy (EC-LTEM), in situ UV–vis spectroelectrochemistry, and extended X-ray absorption fine structure (EXAFS) methods. For the first time, we provided direct evidence of diffuse layer dynamics on the working electrode interface. The results suggested that the formation of cobalt oxyphosphate nanoparticles on the working electrode interface and in the presence of phosphate buffer is the initial stage of the catalytic pathway. Computational results confirmed that the ligand oxidation pathway could occur at potentials below the OER thermodynamic barrier (1.23 V vs reversible hydrogen electrode (RHE)), which leads to a Co ion leaching into the electrolyte. This study showed that investigation of the apparent molecular mechanisms of OER with metal complexes requires careful analyses. We illustrate the high precision and sensitivity of EC-LTEM under operational conditions to monitor heterogeneous catalysts generated during OER and to evaluate their actual roles in the catalytic process.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Wang, Shi-Qiang; Meng, Xiao-Qing; Vandichel, Matthias; Darwish, Shaza; Chang, Ze; Bu, Xian-He; Zaworotko, Michael J
High Working Capacity Acetylene Storage at Ambient Temperature Enabled by a Switching Adsorbent Layered Material Journal Article
In: ACS Applied Materials & Interfaces, vol. 13, no. 20, pp. 23877-23883, 2021, (PMID: 33983706).
@article{doi:10.1021/acsami.1c06241,
title = {High Working Capacity Acetylene Storage at Ambient Temperature Enabled by a Switching Adsorbent Layered Material},
author = {Shi-Qiang Wang and Xiao-Qing Meng and Matthias Vandichel and Shaza Darwish and Ze Chang and Xian-He Bu and Michael J Zaworotko},
url = {https://doi.org/10.1021/acsami.1c06241},
doi = {10.1021/acsami.1c06241},
year = {2021},
date = {2021-05-13},
journal = {ACS Applied Materials & Interfaces},
volume = {13},
number = {20},
pages = {23877-23883},
abstract = {Unlike most gases, acetylene storage is a challenge because of its inherent pressure sensitivity. Herein, a square lattice (sql) coordination network [Cu(4,4′-bipyridine)2(BF4)2]n (sql-1-Cu-BF4) is investigated with respect to its C2H2 sorption behavior from 189 to 298 K. The C2H2 sorption studies revealed that sql-1-Cu-BF4 exhibits multistep isotherms that are temperature-dependent and consistent with the transformation from “closed” (nonporous) to four “open” (porous) phases induced by the C2H2 uptake. The Clausius–Clapeyron equation was used to calculate the performance of sql-1-Cu-BF4 for C2H2 storage at pressures >1 bar, which revealed that its volumetric working capacity at 288 K is slightly superior to acetone (174 vs 170 cm3 cm–3) over a safer pressure range (1–3.5 vs 1–15 bar). Molecular simulations provided insights into the observed switching phenomena, revealing that the layer expansion of sql-1-Cu-BF4 occurs via intercalation and inclusion of C2H2. These results indicate that switching adsorbent layered materials offer promise for utility in the context of C2H2 storage and delivery.},
note = {PMID: 33983706},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Akbari, Nader; Kondov, Ivan; Vandichel, Matthias; Aleshkevych, Pavlo; Najafpour, Mohammad Mahdi
Oxygen-Evolution Reaction by a Palladium Foil in the Presence of Iron Journal Article
In: Inorganic Chemistry, vol. 60, no. 8, pp. 5682–5693, 2021, (PMID: 33826338).
@article{doi:10.1021/acs.inorgchem.0c03746b,
title = {Oxygen-Evolution Reaction by a Palladium Foil in the Presence of Iron},
author = {Nader Akbari and Ivan Kondov and Matthias Vandichel and Pavlo Aleshkevych and Mohammad Mahdi Najafpour},
url = {https://doi.org/10.1021/acs.inorgchem.0c03746},
doi = {10.1021/acs.inorgchem.0c03746},
year = {2021},
date = {2021-04-07},
journal = {Inorganic Chemistry},
volume = {60},
number = {8},
pages = {5682–5693},
abstract = {Herein, we investigate the oxygen-evolution reaction (OER) and electrochemistry of a Pd foil in the presence of iron under alkaline conditions (pH ≈ 13). As a source of iron, K2FeO4 is employed, which is soluble under alkaline conditions in contrast to many other Fe salts. Immediately after reacting with the Pd foil, [FeO4]2– causes a significant increase in OER and changes in the electrochemistry of Pd. In the absence of this Fe source and under OER, Pd(IV) is stable, and hole accumulation occurs, while in the presence of Fe this accumulation of stored charges can be used for OER. A Density Functional Theory (DFT) based thermodynamic model suggests an oxygen bridge vacancy as an active site on the surface of PdO2 and an OER overpotential of 0.42 V. A substitution of Pd with Fe at this active site reduces the calculated OER overpotential to 0.35 V. The 70 mV decrease in overpotential is in good agreement with the experimentally measured decrease of 60 mV in the onset potential. In the presence of small amounts of Fe salt, our results point toward the Fe doping of PdO2 rather than extra framework FeOx (Fe(OH)3, FeO(OH), and KFeO2) species on top of PdO2 as the active OER sites.},
note = {PMID: 33826338},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Pieter Schiettecatte Pengshang Zhou, Matthias Vandichel; Singh, Shalini
Synthesis of Colloidal WSe2 Nanocrystals: Polymorphism Control by Precursor-Ligand Chemistry Journal Article
In: Crystal Growth & Design, vol. 21, no. 3, pp. 1451-1460, 2021.
@article{Zhou2021,
title = {Synthesis of Colloidal WSe2 Nanocrystals: Polymorphism Control by Precursor-Ligand Chemistry},
author = {Pengshang Zhou, Pieter Schiettecatte, Matthias Vandichel, Anastasia Rousaki, Peter Vandenabeele, Zeger Hens, and Shalini Singh},
doi = {https://doi.org/10.1021/acs.cgd.0c01036},
year = {2021},
date = {2021-01-29},
journal = {Crystal Growth & Design},
volume = {21},
number = {3},
pages = {1451-1460},
abstract = {Syntheses of transition-metal dichalcogenides (TMDs) using colloidal-chemistry approaches are gaining significant interest in recent years, as these methods enable the morphology and properties of the nanocrystals to be tuned for targeted applications. In this work, by only varying the ligand used during synthesis, we synthesized nanoflowers with oleic acid (OA) and 1T′ phase dominated WSe2 nanosheets with oleylamine (OLA). WSe2 nanocrystals show slower rate of formation for the metastable 1T′ phase. Surface chemistry analyses of the synthesized nanocrystals by solution NMR establish that neither of the ligands bind strongly to the surface of nanocrystals but are in a dynamic coordination with the WSe2 surface. A further examination of the coordination of tungsten hexacarbonyl (W(CO)6) with the respective ligands confirms that W(CO)6 decomposes in OA, losing its octahedral symmetry, which leads to fast reactivity in the flask. In contrast to this, W(CO)6 reacts with OLA to form a new complex, which leads to slower reactivity and crystallization of the synthesized nanocrystals in the octahedral 1T′ phase. These insights into the influence of precursor-ligand chemistry on reaction outcome and the peculiar surface chemistry of colloidal TMD nanocrystals will be instrumental in developing future colloidal TMD nanocrystals.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2020
Vandichel, Matthias; Laasonen, Kari; Kondov, Ivan
Oxygen Evolution and Reduction on Fe-doped NiOOH: Influence of Solvent, Dopant Position and Reaction Mechanism Journal Article
In: TOPICS IN CATALYSIS, 2020, ISSN: 1022-5528.
@article{ISI:000553709000001,
title = {Oxygen Evolution and Reduction on Fe-doped NiOOH: Influence of Solvent, Dopant Position and Reaction Mechanism},
author = {Matthias Vandichel and Kari Laasonen and Ivan Kondov},
url = {https://doi.org/10.1007/s11244-020-01334-8},
doi = {10.1007/s11244-020-01334-8},
issn = {1022-5528},
year = {2020},
date = {2020-07-29},
journal = {TOPICS IN CATALYSIS},
abstract = {The oxygen evolution reaction (OER) is the limiting factor in an
electrolyzer and the oxygen reduction reaction (ORR) the limiting factor
in a fuel cell. In OER, water is converted to O(2)and H+/e(-)pairs,
while in ORR the reverse process happens to form water. Both reactions
and their efficiency are important enablers of a hydrogen economy where
hydrogen will act as a fuel or energy storage medium. OER and ORR can
both be described assuming a four-step electrochemical mechanism with coupled H+/e(-)transfers between four intermediates (M-*},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
electrolyzer and the oxygen reduction reaction (ORR) the limiting factor
in a fuel cell. In OER, water is converted to O(2)and H+/e(-)pairs,
while in ORR the reverse process happens to form water. Both reactions
and their efficiency are important enablers of a hydrogen economy where
hydrogen will act as a fuel or energy storage medium. OER and ORR can
both be described assuming a four-step electrochemical mechanism with coupled H+/e(-)transfers between four intermediates (M-*
Younus, Hussein A; Zhang, Yan; Vandichel, Matthias; Ahmad, Nazir; Laasonen, Kari; Verpoort, Francis; Zhang, Ce; Zhang, Shiguo
Water Oxidation at Neutral pH using a Highly Active Copper-Based Electrocatalyst Journal Article
In: CHEMSUSCHEM, 2020, ISSN: 1864-5631.
@article{ISI:000557552100001,
title = {Water Oxidation at Neutral pH using a Highly Active Copper-Based Electrocatalyst},
author = {Hussein A Younus and Yan Zhang and Matthias Vandichel and Nazir Ahmad and Kari Laasonen and Francis Verpoort and Ce Zhang and Shiguo Zhang},
doi = {10.1002/cssc.202001444},
issn = {1864-5631},
year = {2020},
date = {2020-07-15},
journal = {CHEMSUSCHEM},
abstract = {The sluggish kinetics of the oxygen evolution reaction (OER) at the
anode severely limit hydrogen production at the cathode in water
splitting systems. Although electrocatalytic systems based on cheap and
earth-abundant copper catalysts have shown promise for water oxidation
under basic conditions, only very few examples with high overpotential
can be operated under acidic or neutral conditions, even though hydrogen
evolution in the latter case is much easier. This work presents an
efficient and robust Cu-based molecular catalyst, which self-assembles
as a periodic film from its precursors under aqueous conditions on the
surface of a glassy carbon electrode. This film catalyzes the OER under
neutral conditions with impressively low overpotential. In controlled
potential electrolysis, a stable catalytic current of 1.0 mA cm(-2)can
be achieved at only 2.0 V (vs. RHE) and no significant decrease in the
catalytic current is observed even after prolonged bulk electrolysis.
The catalyst displays first-order kinetics and a single site mechanism
for water oxidation with a TOF (k(cat)) of 0.6 s(-1). DFT calculations
on of the periodic Cu(TCA)(2)(HTCA=1-mesityl-1H-1,2,3-triazole-4-carboxylic acid) film
reveal that TCA defects within the film create Cu(I)active sites that
provide a low overpotential route for OER, which involves Cu-I, Cu-II-OH},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
anode severely limit hydrogen production at the cathode in water
splitting systems. Although electrocatalytic systems based on cheap and
earth-abundant copper catalysts have shown promise for water oxidation
under basic conditions, only very few examples with high overpotential
can be operated under acidic or neutral conditions, even though hydrogen
evolution in the latter case is much easier. This work presents an
efficient and robust Cu-based molecular catalyst, which self-assembles
as a periodic film from its precursors under aqueous conditions on the
surface of a glassy carbon electrode. This film catalyzes the OER under
neutral conditions with impressively low overpotential. In controlled
potential electrolysis, a stable catalytic current of 1.0 mA cm(-2)can
be achieved at only 2.0 V (vs. RHE) and no significant decrease in the
catalytic current is observed even after prolonged bulk electrolysis.
The catalyst displays first-order kinetics and a single site mechanism
for water oxidation with a TOF (k(cat)) of 0.6 s(-1). DFT calculations
on of the periodic Cu(TCA)(2)(HTCA=1-mesityl-1H-1,2,3-triazole-4-carboxylic acid) film
reveal that TCA defects within the film create Cu(I)active sites that
provide a low overpotential route for OER, which involves Cu-I, Cu-II-OH
Braglia, Luca; Fracchia, Martina; Ghigna, Paolo; Minguzzi, Alessandro; Meroni, Daniela; Edla, Raju; Vandichel, Matthias; Ahlberg, Elisabet; Cerrato, Giuseppina; Torelli, Piero
Understanding Solid-Gas Reaction Mechanisms by Operando Soft X-Ray Absorption Spectroscopy at Ambient Pressure Journal Article
In: JOURNAL OF PHYSICAL CHEMISTRY C, vol. 124, no. 26, pp. 14202-14212, 2020, ISSN: 1932-7447.
@article{ISI:000547455300015,
title = {Understanding Solid-Gas Reaction Mechanisms by Operando Soft X-Ray
Absorption Spectroscopy at Ambient Pressure},
author = {Luca Braglia and Martina Fracchia and Paolo Ghigna and Alessandro Minguzzi and Daniela Meroni and Raju Edla and Matthias Vandichel and Elisabet Ahlberg and Giuseppina Cerrato and Piero Torelli},
doi = {10.1021/acs.jpcc.0c02546},
issn = {1932-7447},
year = {2020},
date = {2020-07-01},
journal = {JOURNAL OF PHYSICAL CHEMISTRY C},
volume = {124},
number = {26},
pages = {14202-14212},
abstract = {Ambient-pressure operando soft X-ray absorption spectroscopy (soft-XAS)
was applied to study the reactivity of hydroxylated SnO(2 )nanoparticles
toward reducing gases. H-2 was first used as a test case, showing that
the gas phase and surface states can be simultaneously probed: Soft-XAS
at the O K-edge gains sensitivity toward the gas phase, while at the Sn
M-4,M-5-edges, tin surface states are explicitly probed. Results
obtained by flowing hydrocarbons (CH4 and CH3CHCH2) unequivocally show
that these gases react with surface hydroxyl groups to produce water
without producing carbon oxides and release electrons that localize on
Sn to eventually form SnO. The partially reduced SnO2-x layer at the
surface of SnO2 is readily reoxidized to SnO2 by treating the sample
with O-2 at mild temperatures (>200 degrees C), revealing the nature of
``electron sponge'' of tin oxide. The experiments, combined with DFT
calculations, allowed devising of a mechanism for dissociative
hydrocarbon adsorption on SnO2, involving direct reduction of Sn sites
at the surface via cleavage of C-H bonds and the formation of methoxy-
and/or methyl-tin species at the surface.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
was applied to study the reactivity of hydroxylated SnO(2 )nanoparticles
toward reducing gases. H-2 was first used as a test case, showing that
the gas phase and surface states can be simultaneously probed: Soft-XAS
at the O K-edge gains sensitivity toward the gas phase, while at the Sn
M-4,M-5-edges, tin surface states are explicitly probed. Results
obtained by flowing hydrocarbons (CH4 and CH3CHCH2) unequivocally show
that these gases react with surface hydroxyl groups to produce water
without producing carbon oxides and release electrons that localize on
Sn to eventually form SnO. The partially reduced SnO2-x layer at the
surface of SnO2 is readily reoxidized to SnO2 by treating the sample
with O-2 at mild temperatures (>200 degrees C), revealing the nature of
``electron sponge'' of tin oxide. The experiments, combined with DFT
calculations, allowed devising of a mechanism for dissociative
hydrocarbon adsorption on SnO2, involving direct reduction of Sn sites
at the surface via cleavage of C-H bonds and the formation of methoxy-
and/or methyl-tin species at the surface.
Song, Bai-Qiao; Yang, Qing-Yuan; Wang, Shi-Qiang; Vandichel, Matthias; Kumar, Amrit; Crowley, Clare; Kumar, Naveen; Deng, Cheng-Hua; GasconPerez, Victoria; Lusi, Matteo; Wu, Hui; Zhou, Wei; Zaworotko, Michael J
Reversible Switching between Nonporous and Porous Phases of a New SIFSIX Coordination Network Induced by a Flexible Linker Ligand Journal Article
In: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 142, no. 15, pp. 6896-6901, 2020, ISSN: 0002-7863.
@article{ISI:000526300600012,
title = {Reversible Switching between Nonporous and Porous Phases of a New SIFSIX
Coordination Network Induced by a Flexible Linker Ligand},
author = {Bai-Qiao Song and Qing-Yuan Yang and Shi-Qiang Wang and Matthias Vandichel and Amrit Kumar and Clare Crowley and Naveen Kumar and Cheng-Hua Deng and Victoria GasconPerez and Matteo Lusi and Hui Wu and Wei Zhou and Michael J Zaworotko},
doi = {10.1021/jacs.0c01314},
issn = {0002-7863},
year = {2020},
date = {2020-04-01},
journal = {JOURNAL OF THE AMERICAN CHEMICAL SOCIETY},
volume = {142},
number = {15},
pages = {6896-6901},
abstract = {Closed-to-open structural transformations in flexible coordination
networks are of potential utility in gas storage and separation. Herein,
we report the first example of a flexible SiF62--pillared square grid material, [Cu(SiF6)(L)(2)](n) (L = 1,4-bis(1-imidazolyl)benzene),
SIFSIX-23-Cu. SIFSIX-23-Cu exhibits reversible switching between
nonporous (beta 1) and several porous (alpha, gamma 1, gamma 2, and
gamma 3) phases triggered by exposure to N-2, CO2, or H2O. In addition,
heating beta 1 to 433 K resulted in irreversible transformation to a
closed polymorph, beta 2. Single-crystal X-ray diffraction studies
revealed that the phase transformations are enabled by rotation and
geometrical contortion of L. Density functional theory calculations
indicated that L exhibits a low barrier to rotation (as low as 8
kJmol(-1)) and a rather flat energy surface. In situ neutron powder
diffraction studies provided further insight into these sorbate-induced
phase changes. SIFSIX-23-Cu combines stability in water for over a year,
high CO2 uptake (ca. 216 cm(3)/g at 195 K), and good thermal stability.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
networks are of potential utility in gas storage and separation. Herein,
we report the first example of a flexible SiF62--pillared square grid material, [Cu(SiF6)(L)(2)](n) (L = 1,4-bis(1-imidazolyl)benzene),
SIFSIX-23-Cu. SIFSIX-23-Cu exhibits reversible switching between
nonporous (beta 1) and several porous (alpha, gamma 1, gamma 2, and
gamma 3) phases triggered by exposure to N-2, CO2, or H2O. In addition,
heating beta 1 to 433 K resulted in irreversible transformation to a
closed polymorph, beta 2. Single-crystal X-ray diffraction studies
revealed that the phase transformations are enabled by rotation and
geometrical contortion of L. Density functional theory calculations
indicated that L exhibits a low barrier to rotation (as low as 8
kJmol(-1)) and a rather flat energy surface. In situ neutron powder
diffraction studies provided further insight into these sorbate-induced
phase changes. SIFSIX-23-Cu combines stability in water for over a year,
high CO2 uptake (ca. 216 cm(3)/g at 195 K), and good thermal stability.
Vandichel, Matthias; Busch, Michael; Laasonen, Kari
Oxygen Evolution on Metal-oxy-hydroxides: Beneficial Role of Mixing Fe, Co, Ni Explained via Bifunctional Edge/acceptor Route Journal Article
In: CHEMCATCHEM, vol. 12, no. 5, pp. 1436-1442, 2020, ISSN: 1867-3880.
@article{ISI:000505822700001,
title = {Oxygen Evolution on Metal-oxy-hydroxides: Beneficial Role of Mixing Fe, Co, Ni Explained via Bifunctional Edge/acceptor Route},
author = {Matthias Vandichel and Michael Busch and Kari Laasonen},
doi = {10.1002/cctc.201901951},
issn = {1867-3880},
year = {2020},
date = {2020-03-01},
journal = {CHEMCATCHEM},
volume = {12},
number = {5},
pages = {1436-1442},
abstract = {Oxygen evolution reaction (OER) via mixed metal oxy hydroxides
[M(O)(OH)] may take place on a large variety of possible active sites
on the actual catalyst. A single site computational description assumes
a 4-step electrochemical mechanism with coupled H+/e(-) transfers between 4 intermediates (M-*, M-OH},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
[M(O)(OH)] may take place on a large variety of possible active sites
on the actual catalyst. A single site computational description assumes
a 4-step electrochemical mechanism with coupled H+/e(-) transfers between 4 intermediates (M-*, M-OH
Younus, H A; Vandichel, M; Ahmad, N; Ahlberg, E; Busch, M; Verpoort, F
Engineering of a highly stable metal-organic Co-film for efficient electrocatalytic water oxidation in acidic media Journal Article
In: Materials Today Energy, vol. 17, pp. 100437, 2020, ISSN: 2468-6069.
@article{YOUNUS2020100437,
title = {Engineering of a highly stable metal-organic Co-film for efficient electrocatalytic water oxidation in acidic media},
author = {H A Younus and M Vandichel and N Ahmad and E Ahlberg and M Busch and F Verpoort},
url = {http://www.sciencedirect.com/science/article/pii/S2468606920300563},
doi = {10.1016/j.mtener.2020.100437},
issn = {2468-6069},
year = {2020},
date = {2020-01-01},
journal = {Materials Today Energy},
volume = {17},
pages = {100437},
abstract = {Water oxidation is traditionally performed over IrO2 and RuO2 owing to their high stability at low pH compared to molecular O2 evolution catalysts. The low stability of molecular complexes in acids limits their industrial exploitation as anodes in water-splitting devices, where high current densities and proton conductivity are required. Herein, an existing Co(1,10-phenanthroline)2 complex film is engineered to improve its pH-stability via extra OH substituents on the ligand, i.e. 1,10-phenanthroline-4,7-diol. This novel Co(1,10-phenanthroline-4,7-diol)2 complex film is active for water oxidation at low overpotentials and stable at low pH. Since the calculated water oxidation overpotentials of both complexes are similar, the difference in water oxidation activity is attributed to a smaller charge transfer resistance, which originates from a different anchoring style to the electrode via the OH groups of the ligand. This result is supported by electrochemical impedance measurements. The high pH-stability of the Co(1,10-phenanthroline-4,7-diol)2 film is computationally rationalized by a high crystal formation energy observed in DFT calculations. In summary, an acid-stable and active cobalt-based metal-organic film is reported that competes well with most reported earth-abundant catalysts for water oxidation under similar conditions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Dhokale, Bhausaheb; Susarrey-Arce, Arturo; Pekkari, Anna; Runemark, August; Moth-Poulsen, Kasper; Langhammer, Christoph; Härelind, Hanna; Busch, Michael; Vandichel, Matthias; Sundén, Henrik
Microwave-heated γ-Alumina Applied to the Reduction of Aldehydes to Alcohols Journal Article
In: ChemCatChem, vol. 12, no. 24, pp. 6344-6355, 2020.
@article{https://doi.org/10.1002/cctc.202001284,
title = {Microwave-heated γ-Alumina Applied to the Reduction of Aldehydes to Alcohols},
author = {Bhausaheb Dhokale and Arturo Susarrey-Arce and Anna Pekkari and August Runemark and Kasper Moth-Poulsen and Christoph Langhammer and Hanna Härelind and Michael Busch and Matthias Vandichel and Henrik Sundén},
url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/cctc.202001284},
doi = {https://doi.org/10.1002/cctc.202001284},
year = {2020},
date = {2020-01-01},
journal = {ChemCatChem},
volume = {12},
number = {24},
pages = {6344-6355},
abstract = {Abstract The development of cheap and robust heterogeneous catalysts for the Meerwein-Ponndorf-Verley (MPV) reduction is desirable due to the difficulties in product isolation and catalyst recovery associated with the traditional use of homogeneous catalysts for MPV. Herein, we show that microwave heated γ-Al2O3 can be used for the reduction of aldehydes to alcohols. The reaction is efficient and has a broad substrates scope (19 entries). The products can be isolated by simple filtration, and the catalyst can be regenerated. With the use of microwave heating, we can direct the heating to the catalyst rather than to the whole reaction medium. Furthermore, DFT was used to study the reaction mechanism, and we can conclude that a dual-site mechanism is operative where the aldehyde and 2-propoxide are situated on two adjacent Al sites during the reduction. Additionally, volcano plots were used to rationalize the reactivity of Al2O3 in comparison to other metal oxides.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Kumar, Naveen; Mukherjee, Soumya; Bezrukov, Andrey A; Vandichel, Matthias; Shivanna, Mohana; Sensharma, Debobroto; Bajpai, Alankriti; Gascón, Victoria; Otake, Ken-ichi; Kitagawa, Susumu; Zaworotko, Michael J
A square lattice topology coordination network that exhibits highly selective C2H2/CO2 separation performance Journal Article
In: SmartMat, vol. 1, no. 1, pp. e1008, 2020.
@article{https://doi.org/10.1002/smm2.1008,
title = {A square lattice topology coordination network that exhibits highly selective C2H2/CO2 separation performance},
author = {Naveen Kumar and Soumya Mukherjee and Andrey A Bezrukov and Matthias Vandichel and Mohana Shivanna and Debobroto Sensharma and Alankriti Bajpai and Victoria Gascón and Ken-ichi Otake and Susumu Kitagawa and Michael J Zaworotko},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/smm2.1008},
doi = {https://doi.org/10.1002/smm2.1008},
year = {2020},
date = {2020-01-01},
journal = {SmartMat},
volume = {1},
number = {1},
pages = {e1008},
abstract = {Abstract C2H2/CO2 separation is an industrially important process that remains challenging because of the similar physicochemical properties of C2H2 and CO2. We herein report that the new square lattice (sql) coordination network [Cu(bipy-xylene)2(NO3)2]n, sql-16-Cu-NO3, 16 = bipy-xylene = 4,4′-(2,5-dimethyl-1,4-phenylene)dipyridine, exists in at least three forms, as-synthesised (α), activated (α′) and hydrated (β). The activated phase, sql-16-Cu-NO3-α′, is an ultramicroporous material that exhibits high selectivity towards C2H2 over CO2 as revealed by dynamic gas breakthrough experiments (1:1, C2H2/CO2) that afforded 99.87% pure CO2 in the effluent stream. The separation selectivity at 298 K and 1 bar, 78, is the third best value yet reported for C2H2 selective physisorbents whereas the mid-loading performance sets a new benchmark. The performance of sql-16-Cu-NO3-α′ is attributed to a new type of C2H2 binding site in which CH···ONO2 interactions enable moderately strong sorbent-sorbate binding (Qst (C2H2) = 38.6 kJ/mol) at low loading. Conversely, weak CO2 binding (Qst (CO2) = 25.6 kJ/mol) at low loading means that (ΔQst)AC [Qst (C2H2)–Qst (CO2)] is 13 kJ/mol at low coverage and 11.4 kJ/mol at mid-loading. Analysis of in situ powder X-ray diffraction and modelling experiments provide insight into the sorption properties and high C2H2/CO2 separation performance of sql-16-Cu-NO3-α′.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2019
Belviso, Florian; Claerbout, Victor E P; Comas-Vives, Aleix; Dalal, Naresh S; Fan, Feng-Ren; Filippetti, Alessio; Fiorentini, Vincenzo; Foppa, Lucas; Franchini, Cesare; Geisler, Benjamin; Ghiringhelli, Luca M; Gross, Axel; Hu, Shunbo; Iniguez, Jorge; Kauwe, Steven Kaai; Musfeldt, Janice L; Nicolini, Paolo; Pentcheva, Rossitza; Polcar, Tomas; Ren, Wei; Ricci, Fabio; Ricci, Francesco; Sen, Huseyin Sener; Skelton, Jonathan Michael; Sparks, Taylor D; Stroppa, Alessandro; Urru, Andrea; Vandichel, Matthias; Vavassori, Paolo; Wu, Hua; Yang, Ke; Zhao, Hong Jian; Puggioni, Danilo; Cortese, Remedios; Cammarata, Antonio
Viewpoint: Atomic-Scale Design Protocols toward Energy, Electronic, Catalysis, and Sensing Applications Journal Article
In: INORGANIC CHEMISTRY, vol. 58, no. 22, pp. 14939-14980, 2019, ISSN: 0020-1669.
@article{ISI:000498288300001,
title = {Viewpoint: Atomic-Scale Design Protocols toward Energy, Electronic,
Catalysis, and Sensing Applications},
author = {Florian Belviso and Victor E P Claerbout and Aleix Comas-Vives and Naresh S Dalal and Feng-Ren Fan and Alessio Filippetti and Vincenzo Fiorentini and Lucas Foppa and Cesare Franchini and Benjamin Geisler and Luca M Ghiringhelli and Axel Gross and Shunbo Hu and Jorge Iniguez and Steven Kaai Kauwe and Janice L Musfeldt and Paolo Nicolini and Rossitza Pentcheva and Tomas Polcar and Wei Ren and Fabio Ricci and Francesco Ricci and Huseyin Sener Sen and Jonathan Michael Skelton and Taylor D Sparks and Alessandro Stroppa and Andrea Urru and Matthias Vandichel and Paolo Vavassori and Hua Wu and Ke Yang and Hong Jian Zhao and Danilo Puggioni and Remedios Cortese and Antonio Cammarata},
doi = {10.1021/acs.inorgchem.9b01785},
issn = {0020-1669},
year = {2019},
date = {2019-11-01},
journal = {INORGANIC CHEMISTRY},
volume = {58},
number = {22},
pages = {14939-14980},
abstract = {Nanostructured materials are essential building blocks for the
fabrication of new devices for energy harvesting/storage, sensing,
catalysis, magnetic, and optoelectronic applications. However, because
of the increase of technological needs, it is essential to identify new
functional materials and improve the properties of existing ones. The
objective of this Viewpoint is to examine the state of the art of
atomic-scale simulative and experimental protocols aimed to the design
of novel functional nanostructured materials, and to present new
perspectives in the relative fields. This is the result of the debates
of Symposium I ``Atomic-scale design protocols towards energy,
electronic, catalysis, and sensing applications'', which took place
within the 2018 European Materials Research Society fall meeting.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
fabrication of new devices for energy harvesting/storage, sensing,
catalysis, magnetic, and optoelectronic applications. However, because
of the increase of technological needs, it is essential to identify new
functional materials and improve the properties of existing ones. The
objective of this Viewpoint is to examine the state of the art of
atomic-scale simulative and experimental protocols aimed to the design
of novel functional nanostructured materials, and to present new
perspectives in the relative fields. This is the result of the debates
of Symposium I ``Atomic-scale design protocols towards energy,
electronic, catalysis, and sensing applications'', which took place
within the 2018 European Materials Research Society fall meeting.
Soldemo, Markus; Vandichel, Matthias; Gronbeck, Henrik; Weissenrieder, Jonas
Initial Fe3O4(100) Formation on Fe(100) Journal Article
In: JOURNAL OF PHYSICAL CHEMISTRY C, vol. 123, no. 26, pp. 16317-16325, 2019, ISSN: 1932-7447.
@article{ISI:000474796600046,
title = {Initial Fe3O4(100) Formation on Fe(100)},
author = {Markus Soldemo and Matthias Vandichel and Henrik Gronbeck and Jonas Weissenrieder},
doi = {10.1021/acs.jpcc.9b04625},
issn = {1932-7447},
year = {2019},
date = {2019-07-01},
journal = {JOURNAL OF PHYSICAL CHEMISTRY C},
volume = {123},
number = {26},
pages = {16317-16325},
abstract = {The initial oxidation of Fe(100) at 400 degrees C has been studied by
X-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy
(STM), and low-energy electron diffraction, in combination with density
functional theory calculations. The first observed well-ordered surface
oxide is formed at a coverage of similar to 3 oxygen atoms per
unreconstructed surface Fe(100) atom. STM shows that this surface oxide
is terminated by straight atomic rows exhibiting a p(2 X 1) periodicity.
However, already for oxide films with a coverage of similar to 4 oxygen
atoms (corresponding to one Fe3O4 unit cell thickness), wiggly atomic
rows appear similar to the c(2 X 2) reconstructed Fe3O4 (100)-surface
with the Fe3O4 unit vectors rotated 45 degrees to Fe(100). The wiggly
rows are a consequence of subsurface cation iron vacancies, which
previously have been observed for bulk surfaces. The formation of
subsurface vacancies is supported by the XPS O is signature, which is
modeled by considering the core-level shifts for all oxygen atoms in the
film. Throughout the oxidation series, the microscopy results reveal a
layer-by-layer (Frank-van der Merwe) growth.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
X-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy
(STM), and low-energy electron diffraction, in combination with density
functional theory calculations. The first observed well-ordered surface
oxide is formed at a coverage of similar to 3 oxygen atoms per
unreconstructed surface Fe(100) atom. STM shows that this surface oxide
is terminated by straight atomic rows exhibiting a p(2 X 1) periodicity.
However, already for oxide films with a coverage of similar to 4 oxygen
atoms (corresponding to one Fe3O4 unit cell thickness), wiggly atomic
rows appear similar to the c(2 X 2) reconstructed Fe3O4 (100)-surface
with the Fe3O4 unit vectors rotated 45 degrees to Fe(100). The wiggly
rows are a consequence of subsurface cation iron vacancies, which
previously have been observed for bulk surfaces. The formation of
subsurface vacancies is supported by the XPS O is signature, which is
modeled by considering the core-level shifts for all oxygen atoms in the
film. Throughout the oxidation series, the microscopy results reveal a
layer-by-layer (Frank-van der Merwe) growth.
Vandichel, Matthias; Gronbeck, Henrik
A dimer path for CO dissociation on PtSn Journal Article
In: CATALYSIS SCIENCE & TECHNOLOGY, vol. 9, no. 3, pp. 695-701, 2019, ISSN: 2044-4753.
@article{ISI:000459731200013,
title = {A dimer path for CO dissociation on PtSn},
author = {Matthias Vandichel and Henrik Gronbeck},
doi = {10.1039/c8cy01989d},
issn = {2044-4753},
year = {2019},
date = {2019-02-01},
journal = {CATALYSIS SCIENCE & TECHNOLOGY},
volume = {9},
number = {3},
pages = {695-701},
abstract = {Density functional theory calculations are used to investigate CO
adsorption, dissociation and SnOX formation on Pt3Sn. We find that
direct CO dissociation is prevented by high activation energies. An
energetically feasible path is instead CO dimer formation followed by
C-O bond cleavage. Dimers are formed in the presence of Sn adatoms which
effectively stabilize anionic OCCO- species. The presence of Sn adatoms
is crucial as dimers are unstable on Pt-only systems. The proposed
mechanism may explain recent experimental observations of SnOX and C-C
formation as PtxSn is exposed to CO.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
adsorption, dissociation and SnOX formation on Pt3Sn. We find that
direct CO dissociation is prevented by high activation energies. An
energetically feasible path is instead CO dimer formation followed by
C-O bond cleavage. Dimers are formed in the presence of Sn adatoms which
effectively stabilize anionic OCCO- species. The presence of Sn adatoms
is crucial as dimers are unstable on Pt-only systems. The proposed
mechanism may explain recent experimental observations of SnOX and C-C
formation as PtxSn is exposed to CO.
2018
Vandichel, Matthias; Gronbeck, Henrik
CO Oxidation at SnO2/Pt3Sn(111) Interfaces Journal Article
In: TOPICS IN CATALYSIS, vol. 61, no. 14, SI, pp. 1458-1464, 2018, ISSN: 1022-5528, (13th European Congress on Catalysis - A Bridge to the Future, Florence, ITALY, AUG 27-31, 2017).
@article{ISI:000445805100009,
title = {CO Oxidation at SnO2/Pt3Sn(111) Interfaces},
author = {Matthias Vandichel and Henrik Gronbeck},
doi = {10.1007/s11244-018-1044-9},
issn = {1022-5528},
year = {2018},
date = {2018-09-01},
journal = {TOPICS IN CATALYSIS},
volume = {61},
number = {14, SI},
pages = {1458-1464},
abstract = {Segregation induced formation of oxide/metal interfaces can
significantly influence the catalytic activity of alloy nanoparticles.
One example is Pt3Sn nanoparticles, which are known to segregate into
SnOX and an Sn deficient alloy phase during typical operating conditions
for CO oxidation. Here, we use density functional theory calculations to
investigate CO oxidation over Pt3Sn(111) supported SnO2 and (SnO2)(3),
representing the initial state of segregation. The results are compared
to CO oxidation at an interface between bulk-like SnO2 and Pt3Sn(111).
The barrier for CO oxidation via a Mars-van Krevelen mechanism is found
to be lower on SnO2 and (SnO2)(3) as compared to the bulk-like model.
However, the regeneration of the finite systems is associated with
higher barriers for O-2 dissociation which may become the rate limiting
step in the low temperature regime where the metal surface can be
assumed to be CO covered.},
note = {13th European Congress on Catalysis - A Bridge to the Future, Florence,
ITALY, AUG 27-31, 2017},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
significantly influence the catalytic activity of alloy nanoparticles.
One example is Pt3Sn nanoparticles, which are known to segregate into
SnOX and an Sn deficient alloy phase during typical operating conditions
for CO oxidation. Here, we use density functional theory calculations to
investigate CO oxidation over Pt3Sn(111) supported SnO2 and (SnO2)(3),
representing the initial state of segregation. The results are compared
to CO oxidation at an interface between bulk-like SnO2 and Pt3Sn(111).
The barrier for CO oxidation via a Mars-van Krevelen mechanism is found
to be lower on SnO2 and (SnO2)(3) as compared to the bulk-like model.
However, the regeneration of the finite systems is associated with
higher barriers for O-2 dissociation which may become the rate limiting
step in the low temperature regime where the metal surface can be
assumed to be CO covered.
Kodan, Nisha; Singh, Aadesh P; Vandichel, Matthias; Wickman, Bjorn; Mehta, B R
In: INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, vol. 43, no. 33, pp. 15773-15783, 2018, ISSN: 0360-3199.
@article{ISI:000442064100014,
title = {Favourable band edge alignment and increased visible light absorption in
beta-MoO3/alpha-MoO3 oxide heterojunction for enhanced
photoelectrochemical performance},
author = {Nisha Kodan and Aadesh P Singh and Matthias Vandichel and Bjorn Wickman and B R Mehta},
doi = {10.1016/j.ijhydene.2018.06.138},
issn = {0360-3199},
year = {2018},
date = {2018-08-01},
journal = {INTERNATIONAL JOURNAL OF HYDROGEN ENERGY},
volume = {43},
number = {33},
pages = {15773-15783},
abstract = {Optimum band gap values, favourable band edge positions and stability in
the electrolyte are critical parameters required for a semiconductor to
have efficient photoelectrode properties. The present investigation
carried out on the phase pure alpha & beta MoO3 thin film shows that
the low bandgap beta-MoO3 possesses a mis-alignment with the water
oxidation potential, while a more suitable band alignment is observed
for the comparatively large bandgap alpha-MoO3. Both experimental and
DFT calculations show that the valence edge of the orthorhombic
(alpha-MoO3) phase is located at a higher energy (0.9 eV higher in
VB-XPS and 1 eV higher in the DOS plots) than the monoclinic (beta-MoO3)
phase, while the conduction edge value is roughly at the same energy
level (-2.5 eV) in both polymorphs. Based on the above investigations,
an all oxide heterojunction comprising of beta-MoO3/alpha-MoO3 is found
to be suitable for improved PEC performance due to favourable energy
band diagram and increased visible light absorption in beta-MoO3.
Significantly higher cathodic photocurrent is observed for the
beta-MoO3/alpha-MoO3 (1.6 mA/cm(2) at applied bias of -0.3V(RHE) under
simulated 1 sun irradiation) as compared to the very low anodic response
in beta-MoO3 (similar to 1.0 nA/cm(2)) and alpha-MoO3 (32 mu A/cm(2)).
(C) 2018 Published by Elsevier Ltd on behalf of Hydrogen Energy
Publications LLC.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
the electrolyte are critical parameters required for a semiconductor to
have efficient photoelectrode properties. The present investigation
carried out on the phase pure alpha & beta MoO3 thin film shows that
the low bandgap beta-MoO3 possesses a mis-alignment with the water
oxidation potential, while a more suitable band alignment is observed
for the comparatively large bandgap alpha-MoO3. Both experimental and
DFT calculations show that the valence edge of the orthorhombic
(alpha-MoO3) phase is located at a higher energy (0.9 eV higher in
VB-XPS and 1 eV higher in the DOS plots) than the monoclinic (beta-MoO3)
phase, while the conduction edge value is roughly at the same energy
level (-2.5 eV) in both polymorphs. Based on the above investigations,
an all oxide heterojunction comprising of beta-MoO3/alpha-MoO3 is found
to be suitable for improved PEC performance due to favourable energy
band diagram and increased visible light absorption in beta-MoO3.
Significantly higher cathodic photocurrent is observed for the
beta-MoO3/alpha-MoO3 (1.6 mA/cm(2) at applied bias of -0.3V(RHE) under
simulated 1 sun irradiation) as compared to the very low anodic response
in beta-MoO3 (similar to 1.0 nA/cm(2)) and alpha-MoO3 (32 mu A/cm(2)).
(C) 2018 Published by Elsevier Ltd on behalf of Hydrogen Energy
Publications LLC.
2017
Vandichel, Matthias; Moscu, Alina; Gronbeck, Henrik
Catalysis at the Rim: A Mechanism for Low Temperature CO Oxidation over Pt3Sn Journal Article
In: ACS CATALYSIS, vol. 7, no. 11, pp. 7431-7441, 2017, ISSN: 2155-5435.
@article{ISI:000414724700006,
title = {Catalysis at the Rim: A Mechanism for Low Temperature CO Oxidation over
Pt3Sn},
author = {Matthias Vandichel and Alina Moscu and Henrik Gronbeck},
doi = {10.1021/acscatal.7b02094},
issn = {2155-5435},
year = {2017},
date = {2017-11-01},
journal = {ACS CATALYSIS},
volume = {7},
number = {11},
pages = {7431-7441},
abstract = {Metal alloying is commonly used as a design strategy for catalyst
optimization. The mechanistic understanding of this class of systems is,
however, obscured by reaction induced segregation phenomena. Herein, the
case of CO oxidation over Pt3Sn is investigated using density functional
theory calculations combined with ab initio thermodynamics and
first-principles based microkinetic modeling. It is found that Pt3Sn
segregates under typical operating conditions into SnOx and an Sn
deficient metal phase. The segregation is driven both by the stability
of the metal oxide and the strong bonding of CO to Pt. The catalytic
consequences of a metal supported SnO2 phase are explored by comparing
CO oxidation at an SnOx/Pt interface with oxidation over Pt and Pt/Pt3Sn
skin models. The reaction is found to proceed with lower barriers at the
interface as compared to the metal-only systems and the cocatalytic role
of the SnOx rim is manifested by low temperature activity. The present
work highlights the effects of reaction-induced metaloxide/metal
interfaces and elucidates the role of Sn in PtSn alloys for CO oxidation
reactions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
optimization. The mechanistic understanding of this class of systems is,
however, obscured by reaction induced segregation phenomena. Herein, the
case of CO oxidation over Pt3Sn is investigated using density functional
theory calculations combined with ab initio thermodynamics and
first-principles based microkinetic modeling. It is found that Pt3Sn
segregates under typical operating conditions into SnOx and an Sn
deficient metal phase. The segregation is driven both by the stability
of the metal oxide and the strong bonding of CO to Pt. The catalytic
consequences of a metal supported SnO2 phase are explored by comparing
CO oxidation at an SnOx/Pt interface with oxidation over Pt and Pt/Pt3Sn
skin models. The reaction is found to proceed with lower barriers at the
interface as compared to the metal-only systems and the cocatalytic role
of the SnOx rim is manifested by low temperature activity. The present
work highlights the effects of reaction-induced metaloxide/metal
interfaces and elucidates the role of Sn in PtSn alloys for CO oxidation
reactions.
Younus, Hussein A; Ahmad, Nazir; Chughtai, Adeel H; Vandichel, Matthias; Busch, Michael; Hecke, Kristof Van; Yusubov, Mekhman; Song, Shaoxian; Verpoort, Francis
A Robust Molecular Catalyst Generated In Situ for Photoand Electrochemical Water Oxidation Journal Article
In: CHEMSUSCHEM, vol. 10, no. 5, pp. 862-875, 2017, ISSN: 1864-5631.
@article{ISI:000398182300008,
title = {A Robust Molecular Catalyst Generated In Situ for Photoand
Electrochemical Water Oxidation},
author = {Hussein A Younus and Nazir Ahmad and Adeel H Chughtai and Matthias Vandichel and Michael Busch and Kristof Van Hecke and Mekhman Yusubov and Shaoxian Song and Francis Verpoort},
doi = {10.1002/cssc.201601477},
issn = {1864-5631},
year = {2017},
date = {2017-03-01},
journal = {CHEMSUSCHEM},
volume = {10},
number = {5},
pages = {862-875},
abstract = {Water splitting is the key step towards artificial photosystems for
solar energy conversion and storage in the form of chemical bonding. The
oxidation of water is the bottle-neck of this process that hampers its
practical utility; hence, efficient, robust, and easy to make catalytic
systems based on cheap and earth-abundant materials are of exceptional
importance. Herein, an in situ generated cobalt catalyst,
[Co-II(TCA)(2)(H2O)(2)] (TCA=1-mesityl-1,2,3-1H-triazole-4-carboxylate), that efficiently
conducts photochemical water oxidation under near-neutral conditions is
presented. The catalyst showed high stability under photolytic
conditions for more than 3 h of photoirradiation. During electrochemical
water oxidation, the catalytic system assembled a catalyst film, which
proved not to be cobalt oxide/hydroxide as normally expected, but
instead, and for the first time, generated a molecular cobalt complex
that incorporated the organic ligand bound to cobalt ions. The catalyst
film exhibited a low overpotential for electrocatalytic water oxidation
(360 mV) and high oxygen evolution peak current densities of 9 and 2.7
mA cm(-2) on glassy carbon and indium-doped tin oxide electrodes,
respectively, at only 1.49 and 1.39 V ( versus a normal hydrogen
electrode), respectively, under neutral conditions. This finding,
exemplified on the in situ generated cobalt complex, might be applicable
to other molecular systems and suggests that the formation of a
catalytic film in electrochemical water oxidation experiments is not
always an indication of catalyst decomposition and the formation of
nanoparticles.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
solar energy conversion and storage in the form of chemical bonding. The
oxidation of water is the bottle-neck of this process that hampers its
practical utility; hence, efficient, robust, and easy to make catalytic
systems based on cheap and earth-abundant materials are of exceptional
importance. Herein, an in situ generated cobalt catalyst,
[Co-II(TCA)(2)(H2O)(2)] (TCA=1-mesityl-1,2,3-1H-triazole-4-carboxylate), that efficiently
conducts photochemical water oxidation under near-neutral conditions is
presented. The catalyst showed high stability under photolytic
conditions for more than 3 h of photoirradiation. During electrochemical
water oxidation, the catalytic system assembled a catalyst film, which
proved not to be cobalt oxide/hydroxide as normally expected, but
instead, and for the first time, generated a molecular cobalt complex
that incorporated the organic ligand bound to cobalt ions. The catalyst
film exhibited a low overpotential for electrocatalytic water oxidation
(360 mV) and high oxygen evolution peak current densities of 9 and 2.7
mA cm(-2) on glassy carbon and indium-doped tin oxide electrodes,
respectively, at only 1.49 and 1.39 V ( versus a normal hydrogen
electrode), respectively, under neutral conditions. This finding,
exemplified on the in situ generated cobalt complex, might be applicable
to other molecular systems and suggests that the formation of a
catalytic film in electrochemical water oxidation experiments is not
always an indication of catalyst decomposition and the formation of
nanoparticles.
Velazquez, Heriberto Diaz; Wu, Zhao-Xuan; Vandichel, Matthias; Verpoort, Francis
Inserting CO2 into Terminal Alkynes via Bis-(NHC)-Metal Complexes Journal Article
In: CATALYSIS LETTERS, vol. 147, no. 2, pp. 463-471, 2017, ISSN: 1011-372X.
@article{ISI:000394359600017,
title = {Inserting CO2 into Terminal Alkynes via Bis-(NHC)-Metal Complexes},
author = {Heriberto Diaz Velazquez and Zhao-Xuan Wu and Matthias Vandichel and Francis Verpoort},
doi = {10.1007/s10562-016-1920-5},
issn = {1011-372X},
year = {2017},
date = {2017-02-01},
journal = {CATALYSIS LETTERS},
volume = {147},
number = {2},
pages = {463-471},
abstract = {The direct interaction between CO2 and terminal alkynes in the presence
of bis-(NHC)-metal catalysts at ambient conditions was studied. Two Cu
and Ag-based bis-N-heterocyclic carbene Transition Metal catalysts were
synthesized. The (NHC)(2)-Ag complex showed a better catalytic
performance towards the carboxylation of terminal alkynes in comparison
with the copper analogue even for the conversion of acetylene gas. The
optimized conditions for the carboxylation are: the use of Cs2CO3 as
additive, one atmosphere CO2 and room temperature using 1% mol
catalyst. Mechanistic insight into the reaction mechanism is obtained by
means of state-of-the-art first principles calculations.
[GRAPHICS]
.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
of bis-(NHC)-metal catalysts at ambient conditions was studied. Two Cu
and Ag-based bis-N-heterocyclic carbene Transition Metal catalysts were
synthesized. The (NHC)(2)-Ag complex showed a better catalytic
performance towards the carboxylation of terminal alkynes in comparison
with the copper analogue even for the conversion of acetylene gas. The
optimized conditions for the carboxylation are: the use of Cs2CO3 as
additive, one atmosphere CO2 and room temperature using 1% mol
catalyst. Mechanistic insight into the reaction mechanism is obtained by
means of state-of-the-art first principles calculations.
[GRAPHICS]
.
2016
Filippousi, Maria; Turner, Stuart; Leus, Karen; Siafaka, Panoraia I; Tseligka, Eirini D; Vandichel, Matthias; Nanaki, Stavroula G; Vizirianakis, Ioannis S; Bikiaris, Dimitrios N; der Voort, Pascal Van; Tendeloo, Gustaaf Van
Biocompatible Zr-based nanoscale MOFs coated with modified poly (epsilon-caprolactone) as anticancer drug carriers Journal Article
In: INTERNATIONAL JOURNAL OF PHARMACEUTICS, vol. 509, no. 1-2, pp. 208-218, 2016, ISSN: 0378-5173.
@article{ISI:000378949800022,
title = {Biocompatible Zr-based nanoscale MOFs coated with modified poly
(epsilon-caprolactone) as anticancer drug carriers},
author = {Maria Filippousi and Stuart Turner and Karen Leus and Panoraia I Siafaka and Eirini D Tseligka and Matthias Vandichel and Stavroula G Nanaki and Ioannis S Vizirianakis and Dimitrios N Bikiaris and Pascal Van der Voort and Gustaaf Van Tendeloo},
doi = {10.1016/j.ijpharm.2016.05.048},
issn = {0378-5173},
year = {2016},
date = {2016-07-01},
journal = {INTERNATIONAL JOURNAL OF PHARMACEUTICS},
volume = {509},
number = {1-2},
pages = {208-218},
abstract = {Nanoscale Zr-based metal organic frameworks (MOFs) UiO-66 and UiO-67
were studied as potential anticancer drug delivery vehicles. Two model
drugs were used, hydrophobic paclitaxel and hydrophilic cisplatin, and
were adsorbed onto/into the nano MOFs (NMOFs). The drug loaded MOFs were
further encapsulated inside a modified poly(epsilon-caprolactone) with
D-alpha-tocopheryl polyethylene glycol succinate polymeric matrix, in
the form of microparticles, in order to prepare sustained release
formulations and to reduce the drug toxicity. The drugs physical state
and release rate was studied at 37 degrees C using Simulated Body Fluid.
It was found that the drug release depends on the interaction between
the MOFs and the drugs while the controlled release rates can be
attributed to the microencapsulated formulations. The in vitro antitumor
activity was assessed using HSC-3 (human oral squamous carcinoma; head
and neck) and U-87 MG (human glioblastoma grade IV; astrocytoma) cancer
cells. Cytotoxicity studies for both cell lines showed that the polymer
coated, drug loaded MOFs exhibited better anticancer activity compared
to free paclitaxel and cisplatin solutions at different concentrations.
(C) 2016 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
were studied as potential anticancer drug delivery vehicles. Two model
drugs were used, hydrophobic paclitaxel and hydrophilic cisplatin, and
were adsorbed onto/into the nano MOFs (NMOFs). The drug loaded MOFs were
further encapsulated inside a modified poly(epsilon-caprolactone) with
D-alpha-tocopheryl polyethylene glycol succinate polymeric matrix, in
the form of microparticles, in order to prepare sustained release
formulations and to reduce the drug toxicity. The drugs physical state
and release rate was studied at 37 degrees C using Simulated Body Fluid.
It was found that the drug release depends on the interaction between
the MOFs and the drugs while the controlled release rates can be
attributed to the microencapsulated formulations. The in vitro antitumor
activity was assessed using HSC-3 (human oral squamous carcinoma; head
and neck) and U-87 MG (human glioblastoma grade IV; astrocytoma) cancer
cells. Cytotoxicity studies for both cell lines showed that the polymer
coated, drug loaded MOFs exhibited better anticancer activity compared
to free paclitaxel and cisplatin solutions at different concentrations.
(C) 2016 Elsevier B.V. All rights reserved.
Vandichel, M; Hajek, J; Ghysels, A; Vos, A De; Waroquier, M; Speybroeck, V Van
Water coordination and dehydration processes in defective UiO-66 type metal organic frameworks Journal Article
In: CRYSTENGCOMM, vol. 18, no. 37, pp. 7056-7069, 2016, ISSN: 1466-8033.
@article{ISI:000384465500012,
title = {Water coordination and dehydration processes in defective UiO-66 type
metal organic frameworks},
author = {M Vandichel and J Hajek and A Ghysels and A De Vos and M Waroquier and V Van Speybroeck},
doi = {10.1039/c6ce01027j},
issn = {1466-8033},
year = {2016},
date = {2016-01-01},
journal = {CRYSTENGCOMM},
volume = {18},
number = {37},
pages = {7056-7069},
abstract = {The UiO-66 metal organic framework is one of the most thermally and
chemically stable hybrid materials reported to date. However, it is also
accepted that the material contains structurally embedded defects, which
may be engineered to enhance properties towards specific applications
such as catalysis, sensing, etc. The synthesis conditions determine to a
large extent the level of perfection of the material and additionally
the catalytic activity may be enhanced by post-synthesis activation at
high temperature under vacuum, in which defect coordinating species
(H2O, HCl, monocarboxylic modulators, etc.) evaporate. The molecular
level characterization of defects is extremely challenging from both
theoretical and experimental points of view. Such experimental endeavor
was recently proposed via experimental SXRD measurements, also
unraveling the coordination of water on the Zr-O-Zr defect sites
[Angew. Chem., Int. Ed., 2015, 54, 11162-11167]. The present work
provides a theoretical understanding of defect structures in UiO-66(Zr)
by means of periodic density functional theory calculations and ab
initio molecular dynamics simulations. A range of defect structures are
generated with different numbers of missing linkers. For each of the
defects, the free energetic and mechanical stability is discussed and
the coordination of water and charge balancing hydroxide ions is
studied. For catalysis applications, the material is mostly pretreated
to remove water by dehydration reactions. For each of the proposed
defect structures, mechanistic pathways for dehydration reactions of the
Zr-bricks are determined employing nudged elastic band (NEB)
calculations. During the dehydroxylation trajectory, loose hydroxyl
groups and terephthalate decoordinations are observed. Furthermore,
dehydration reactions are lower activated if terephthalate linkers are
missing in the immediate environment of the inorganic brick. The
creation of defects and the dehydration processes have a large impact on
the mechanical properties of the material, which is evidenced by lower
bulk moduli and elastic constants for structures with more defects.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
chemically stable hybrid materials reported to date. However, it is also
accepted that the material contains structurally embedded defects, which
may be engineered to enhance properties towards specific applications
such as catalysis, sensing, etc. The synthesis conditions determine to a
large extent the level of perfection of the material and additionally
the catalytic activity may be enhanced by post-synthesis activation at
high temperature under vacuum, in which defect coordinating species
(H2O, HCl, monocarboxylic modulators, etc.) evaporate. The molecular
level characterization of defects is extremely challenging from both
theoretical and experimental points of view. Such experimental endeavor
was recently proposed via experimental SXRD measurements, also
unraveling the coordination of water on the Zr-O-Zr defect sites
[Angew. Chem., Int. Ed., 2015, 54, 11162-11167]. The present work
provides a theoretical understanding of defect structures in UiO-66(Zr)
by means of periodic density functional theory calculations and ab
initio molecular dynamics simulations. A range of defect structures are
generated with different numbers of missing linkers. For each of the
defects, the free energetic and mechanical stability is discussed and
the coordination of water and charge balancing hydroxide ions is
studied. For catalysis applications, the material is mostly pretreated
to remove water by dehydration reactions. For each of the proposed
defect structures, mechanistic pathways for dehydration reactions of the
Zr-bricks are determined employing nudged elastic band (NEB)
calculations. During the dehydroxylation trajectory, loose hydroxyl
groups and terephthalate decoordinations are observed. Furthermore,
dehydration reactions are lower activated if terephthalate linkers are
missing in the immediate environment of the inorganic brick. The
creation of defects and the dehydration processes have a large impact on
the mechanical properties of the material, which is evidenced by lower
bulk moduli and elastic constants for structures with more defects.
Canivet, J; Vandichel, M; Farrusseng, D
Origin of highly active metal-organic framework catalysts: defects? Defects! Journal Article
In: DALTON TRANSACTIONS, vol. 45, no. 10, pp. 4090-4099, 2016, ISSN: 1477-9226.
@article{ISI:000371710500004,
title = {Origin of highly active metal-organic framework catalysts: defects?
Defects!},
author = {J Canivet and M Vandichel and D Farrusseng},
doi = {10.1039/c5dt03522h},
issn = {1477-9226},
year = {2016},
date = {2016-01-01},
journal = {DALTON TRANSACTIONS},
volume = {45},
number = {10},
pages = {4090-4099},
abstract = {This article provides a comprehensive review of the nature of catalytic
sites in MOFs. In the last decade, a number of striking studies have
reported outstanding catalytic activities of MOFs. In all cases, the
authors were intrigued as it was unexpected from the ideal structure. We
demonstrate here that (surface) defects are at the origin of the
catalytic activities for the reported examples. The vacancy of ligands
or linkers systematically generates (surface) terminations which can
possibly show Lewis and/or Bronsted acido-basic features. The
engineering of catalytic sites at the nodes by the creation of defects
(on purpose) appears today as a rational approach for the design of
active MOFs. Similarly to zeolite post-treatments, post-modifications of
MOFs by linker or metal cation exchange appear to be methods of choice.
Despite the mild acidity of defective MOFs, we can account for very
active MOFs in a number of catalytic applications which show higher
performances than zeolites or benchmark catalysts.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
sites in MOFs. In the last decade, a number of striking studies have
reported outstanding catalytic activities of MOFs. In all cases, the
authors were intrigued as it was unexpected from the ideal structure. We
demonstrate here that (surface) defects are at the origin of the
catalytic activities for the reported examples. The vacancy of ligands
or linkers systematically generates (surface) terminations which can
possibly show Lewis and/or Bronsted acido-basic features. The
engineering of catalytic sites at the nodes by the creation of defects
(on purpose) appears today as a rational approach for the design of
active MOFs. Similarly to zeolite post-treatments, post-modifications of
MOFs by linker or metal cation exchange appear to be methods of choice.
Despite the mild acidity of defective MOFs, we can account for very
active MOFs in a number of catalytic applications which show higher
performances than zeolites or benchmark catalysts.
2015
Hajek, Julianna; Vandichel, Matthias; de Voorde, Ben Van; Bueken, Bart; Vos, Dirk De; Waroquier, Michel; Speybroeck, Veronique Van
Mechanistic studies of aldol condensations in UiO-66 and UiO-66-NH2 metal organic frameworks Journal Article
In: JOURNAL OF CATALYSIS, vol. 331, pp. 1-12, 2015, ISSN: 0021-9517.
@article{ISI:000364250800001,
title = {Mechanistic studies of aldol condensations in UiO-66 and UiO-66-NH2
metal organic frameworks},
author = {Julianna Hajek and Matthias Vandichel and Ben Van de Voorde and Bart Bueken and Dirk De Vos and Michel Waroquier and Veronique Van Speybroeck},
doi = {10.1016/j.jcat.2015.08.015},
issn = {0021-9517},
year = {2015},
date = {2015-11-01},
journal = {JOURNAL OF CATALYSIS},
volume = {331},
pages = {1-12},
abstract = {A full mechanistic investigation is proposed for the industrially
important cross-aldol condensation reaction of heptanal with
benzaldehyde on the UiO-66 and the amino-functionalized UiO-66-NH2
metal-organic frameworks to form jasminaldehyde. Several experimental
studies indicate that the activity for the aldol condensation reaction
can be increased by proper functionalization of the material, e.g. by
introducing an additional basic amino site and thus creating a
bifunctional acid-base catalyst for the aldol condensation. The precise
molecular level origin for this behavior is to date unclear. Herein
state-of-the-art Density-Functional Theory (DFT) calculations have been
performed to unravel the mechanism of the cross- and self-aldol
condensations of benzaldehyde and propanal. To this end free energy
calculations have been performed on both extended cluster and periodic
models. It is found that the mechanism on both catalysts is essentially
the same, although a slightly stronger adsorption of the reactants and
slightly lower barriers were found on the amino functionalized material,
pointing toward higher initial activities. New experiments were
performed to confirm these observations. It is indeed found that the
initial activity toward cross-aldol condensation on the amino
functionalized material is higher, although after about 40 min of
reaction both materials become equally active. Our results furthermore
point out that the basic amino groups may promote side reactions such as
imine formation, which is induced by water. The study as presented can
assist to engineer materials at the molecular level toward the desired
products. (C) 2015 Elsevier Inc. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
important cross-aldol condensation reaction of heptanal with
benzaldehyde on the UiO-66 and the amino-functionalized UiO-66-NH2
metal-organic frameworks to form jasminaldehyde. Several experimental
studies indicate that the activity for the aldol condensation reaction
can be increased by proper functionalization of the material, e.g. by
introducing an additional basic amino site and thus creating a
bifunctional acid-base catalyst for the aldol condensation. The precise
molecular level origin for this behavior is to date unclear. Herein
state-of-the-art Density-Functional Theory (DFT) calculations have been
performed to unravel the mechanism of the cross- and self-aldol
condensations of benzaldehyde and propanal. To this end free energy
calculations have been performed on both extended cluster and periodic
models. It is found that the mechanism on both catalysts is essentially
the same, although a slightly stronger adsorption of the reactants and
slightly lower barriers were found on the amino functionalized material,
pointing toward higher initial activities. New experiments were
performed to confirm these observations. It is indeed found that the
initial activity toward cross-aldol condensation on the amino
functionalized material is higher, although after about 40 min of
reaction both materials become equally active. Our results furthermore
point out that the basic amino groups may promote side reactions such as
imine formation, which is induced by water. The study as presented can
assist to engineer materials at the molecular level toward the desired
products. (C) 2015 Elsevier Inc. All rights reserved.
Vandichel, Matthias; Hajek, Julianna; Vermoortele, Frederik; Waroquier, Michel; Vos, Dirk E De; Speybroeck, Veronique Van
Active site engineering in UiO-66 type metal-organic frameworks by intentional creation of defects: a theoretical rationalization Journal Article
In: CRYSTENGCOMM, vol. 17, no. 2, pp. 395-406, 2015, ISSN: 1466-8033.
@article{ISI:000346173200024,
title = {Active site engineering in UiO-66 type metal-organic frameworks by
intentional creation of defects: a theoretical rationalization},
author = {Matthias Vandichel and Julianna Hajek and Frederik Vermoortele and Michel Waroquier and Dirk E De Vos and Veronique Van Speybroeck},
doi = {10.1039/c4ce01672f},
issn = {1466-8033},
year = {2015},
date = {2015-01-01},
journal = {CRYSTENGCOMM},
volume = {17},
number = {2},
pages = {395-406},
abstract = {The catalytic activity of the Zr-benzenedicarboxylate (Zr-BDC) UiO-66
can be drastically increased if some BDC linkers are missing, as this
removes the full coordination of the framework metal ions. As a result,
metal centers become more accessible and thus more active for Lewis acid
catalysed reactions. Addition of modulators (MDL) to the synthesis
mixture can create more linker deficiencies (Vermoortele et al., J. Am.
Chem. Soc., 2013, 135, 11465) and leads to a significant increase in the
catalytic activity due to the creation of a larger number of open sites.
In this paper, we rationalize the function of the modulators under real
synthesis conditions by the construction of free energy diagrams. The
UiO-66 type materials form a very appropriate test case as the effect of
addition of modulators hydrochloric acid (HCl) and trifluoroacetate
(TFA) has been intensively investigated experimentally for the synthesis
process and post-synthetic thermal activation. Under synthesis
conditions, direct removal of BDC linkers requires a high free energy,
but replacement of such linker by one or more TFA species might occur
especially at high TFA : BDC ratios in the reaction mixture.
Post-synthesis activation procedures at higher temperatures lead to
substantial removal of the species coordinated to the Zr bricks,
creating open metal sites. A mechanistic pathway is presented for the
dehydroxylation process of the hexanuclear Zr cluster. For the
citronellal cyclization, we show that the presence of some residual TFA
in the structure may lead to faster reactions in complete agreement with
the experiment. Hirshfeld-e partial charges for the Zr ions have been
computed to investigate their sensitivity to substituent effects; a
strong correlation with the experimental Hammett parameters and with the
rates of the citronellal cyclization is found. The theoretical
rationalization may serve as a basis for detailed active site
engineering studies.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
can be drastically increased if some BDC linkers are missing, as this
removes the full coordination of the framework metal ions. As a result,
metal centers become more accessible and thus more active for Lewis acid
catalysed reactions. Addition of modulators (MDL) to the synthesis
mixture can create more linker deficiencies (Vermoortele et al., J. Am.
Chem. Soc., 2013, 135, 11465) and leads to a significant increase in the
catalytic activity due to the creation of a larger number of open sites.
In this paper, we rationalize the function of the modulators under real
synthesis conditions by the construction of free energy diagrams. The
UiO-66 type materials form a very appropriate test case as the effect of
addition of modulators hydrochloric acid (HCl) and trifluoroacetate
(TFA) has been intensively investigated experimentally for the synthesis
process and post-synthetic thermal activation. Under synthesis
conditions, direct removal of BDC linkers requires a high free energy,
but replacement of such linker by one or more TFA species might occur
especially at high TFA : BDC ratios in the reaction mixture.
Post-synthesis activation procedures at higher temperatures lead to
substantial removal of the species coordinated to the Zr bricks,
creating open metal sites. A mechanistic pathway is presented for the
dehydroxylation process of the hexanuclear Zr cluster. For the
citronellal cyclization, we show that the presence of some residual TFA
in the structure may lead to faster reactions in complete agreement with
the experiment. Hirshfeld-e partial charges for the Zr ions have been
computed to investigate their sensitivity to substituent effects; a
strong correlation with the experimental Hammett parameters and with the
rates of the citronellal cyclization is found. The theoretical
rationalization may serve as a basis for detailed active site
engineering studies.
Leus, K; Concepcion, P; Vandichel, M; Meledina, M; Grirrane, A; Esquivel, D; Turner, S; Poelman, D; Waroquier, M; Speybroeck, V Van; Tendeloo, G Van; Garcia, H; Voort, P Van Der
Au@UiO-66: a base free oxidation catalyst Journal Article
In: RSC ADVANCES, vol. 5, no. 29, pp. 22334-22342, 2015, ISSN: 2046-2069.
@article{ISI:000350643700005,
title = {Au@UiO-66: a base free oxidation catalyst},
author = {K Leus and P Concepcion and M Vandichel and M Meledina and A Grirrane and D Esquivel and S Turner and D Poelman and M Waroquier and V Van Speybroeck and G Van Tendeloo and H Garcia and P Van Der Voort},
doi = {10.1039/c4ra16800c},
issn = {2046-2069},
year = {2015},
date = {2015-01-01},
journal = {RSC ADVANCES},
volume = {5},
number = {29},
pages = {22334-22342},
abstract = {We present the in situ synthesis of Au nanoparticles within the Zr based Metal Organic Framework, UiO-66. The resulting Au@UiO-66 materials were
characterized by means of N-2 sorption, XRPD, UV-Vis, XRF, XPS and TEM
analysis. The Au nanoparticles (NP) are homogeneously distributed along
the UiO-66 host matrix when using NaBH4 or H-2 as reducing agents. The Au@UiO-66 materials were evaluated as catalysts in the oxidation of benzyl alcohol and benzyl amine employing O-2 as oxidant. The Au@MOF
materials exhibit a very high selectivity towards the ketone (up to
100%). Regenerability and stability tests demonstrate that the Au@UiO-66 catalyst can be recycled with a negligible loss of Au species
and no loss of crystallinity. In situ IR measurements of UiO-66 and Au@UiO-66-NaBH4, before and after treatment with alcohol, showed an
increase in IR bands that can be assigned to a combination of
physisorbed and chemisorbed alcohol species. This was confirmed by
velocity power spectra obtained from the molecular dynamics simulations.
Active peroxo and oxo species on Au could be visualized with Raman
analysis.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
characterized by means of N-2 sorption, XRPD, UV-Vis, XRF, XPS and TEM
analysis. The Au nanoparticles (NP) are homogeneously distributed along
the UiO-66 host matrix when using NaBH4 or H-2 as reducing agents. The Au@UiO-66 materials were evaluated as catalysts in the oxidation of benzyl alcohol and benzyl amine employing O-2 as oxidant. The Au@MOF
materials exhibit a very high selectivity towards the ketone (up to
100%). Regenerability and stability tests demonstrate that the Au@UiO-66 catalyst can be recycled with a negligible loss of Au species
and no loss of crystallinity. In situ IR measurements of UiO-66 and Au@UiO-66-NaBH4, before and after treatment with alcohol, showed an
increase in IR bands that can be assigned to a combination of
physisorbed and chemisorbed alcohol species. This was confirmed by
velocity power spectra obtained from the molecular dynamics simulations.
Active peroxo and oxo species on Au could be visualized with Raman
analysis.
Leus, K; Concepcion, P; Vandichel, M; Meledina, M; Grirrane, A; Esquivel, D; Turner, S; Poelman, D; Waroquier, M; Speybroeck, V Van; Tendeloo, G Van; Garcia, H; der Voort, P Van
Au@UiO-66: a base free oxidation catalyst (vol 5, pg 22334, 2015) Journal Article
In: RSC ADVANCES, vol. 5, no. 34, pp. 26726, 2015, ISSN: 2046-2069.
@article{ISI:000351556800034,
title = {Au@UiO-66: a base free oxidation catalyst (vol 5, pg 22334, 2015)},
author = {K Leus and P Concepcion and M Vandichel and M Meledina and A Grirrane and D Esquivel and S Turner and D Poelman and M Waroquier and V Van Speybroeck and G Van Tendeloo and H Garcia and P Van der Voort},
doi = {10.1039/c5ra90022k},
issn = {2046-2069},
year = {2015},
date = {2015-01-01},
journal = {RSC ADVANCES},
volume = {5},
number = {34},
pages = {26726},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2014
Vandichel, Matthias; Biswas, Shyam; Leus, Karen; Paier, Joachim; Sauer, Joachim; Verstraelen, Toon; der Voort, Pascal Van; Waroquier, Michel; Speybroeck, Veronique Van
In: CHEMPLUSCHEM, vol. 79, no. 8, pp. 1183-1197, 2014, ISSN: 2192-6506.
@article{ISI:000340508000016,
title = {Catalytic Performance of Vanadium MIL-47 and Linker-Substituted Variants
in the Oxidation of Cyclohexene: A Combined Theoretical and Experimental
Approach},
author = {Matthias Vandichel and Shyam Biswas and Karen Leus and Joachim Paier and Joachim Sauer and Toon Verstraelen and Pascal Van der Voort and Michel Waroquier and Veronique Van Speybroeck},
doi = {10.1002/cplu.201402007},
issn = {2192-6506},
year = {2014},
date = {2014-08-01},
journal = {CHEMPLUSCHEM},
volume = {79},
number = {8},
pages = {1183-1197},
abstract = {The epoxidation of cyclohexene has been investigated on a metal-organic
framework MIL-47 containing saturated V+IV sites linked with functionalized terephthalate linkers (MIL-47-X},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
framework MIL-47 containing saturated V+IV sites linked with functionalized terephthalate linkers (MIL-47-X
Valvekens, Pieterjan; Vandichel, Matthias; Waroquier, Michel; Speybroeck, Veronique Van; Vos, Dirk De
Metal-dioxidoterephthalate MOFs of the MOF-74 type: Microporous basic catalysts with well-defined active sites Journal Article
In: JOURNAL OF CATALYSIS, vol. 317, pp. 1-10, 2014, ISSN: 0021-9517.
@article{ISI:000341473000001,
title = {Metal-dioxidoterephthalate MOFs of the MOF-74 type: Microporous basic
catalysts with well-defined active sites},
author = {Pieterjan Valvekens and Matthias Vandichel and Michel Waroquier and Veronique Van Speybroeck and Dirk De Vos},
doi = {10.1016/j.jcat.2014.06.006},
issn = {0021-9517},
year = {2014},
date = {2014-08-01},
journal = {JOURNAL OF CATALYSIS},
volume = {317},
pages = {1-10},
abstract = {The hybrid frameworks M(2)dobdc (dobdc(4-) = 2,5-dioxidoterephthalate, M2+ = Mg2+, Co2+, Ni2+, Cu2+ and Zn2+), commonly known as CPO-27 or
MOF-74, are shown to be active catalysts in base-catalyzed reactions
such as Knoevenagel condensations or Michael additions. Rather than
utilizing N-functionalized linkers as a source of basicity, the
intrinsic basicity of these materials arises from the presence of the
phenolate oxygen atoms coordinated to the metal ions. The overall
activity is due to a complex interplay of the basic properties of these
structural phenolates and the reactant binding characteristics of the
coordinatively unsaturated sites. The nature of the active site and the
order of activity between the different M(2)dobdc materials were
rationalized via computational efforts; the most active material, both
in theory and in experiment, is the Ni-containing variant. The basicity
of Ni(2)dobdc was experimentally proven by chemisorption of pyrrole and
observation by IR spectroscopy. (C) 2014 Elsevier Inc. All rights
reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
MOF-74, are shown to be active catalysts in base-catalyzed reactions
such as Knoevenagel condensations or Michael additions. Rather than
utilizing N-functionalized linkers as a source of basicity, the
intrinsic basicity of these materials arises from the presence of the
phenolate oxygen atoms coordinated to the metal ions. The overall
activity is due to a complex interplay of the basic properties of these
structural phenolates and the reactant binding characteristics of the
coordinatively unsaturated sites. The nature of the active site and the
order of activity between the different M(2)dobdc materials were
rationalized via computational efforts; the most active material, both
in theory and in experiment, is the Ni-containing variant. The basicity
of Ni(2)dobdc was experimentally proven by chemisorption of pyrrole and
observation by IR spectroscopy. (C) 2014 Elsevier Inc. All rights
reserved.
Valvekens, P; Jonckheere, D; Baerdemaeker, T De; Kubarev, A V; Vandichel, M; Hemelsoet, K; Waroquier, M; Speybroeck, V Van; Smolders, E; Depla, D; Roeffaers, M B J; Vos, D De
In: CHEMICAL SCIENCE, vol. 5, no. 11, pp. 4517-4524, 2014, ISSN: 2041-6520.
@article{ISI:000343004300050,
title = {Base catalytic activity of alkaline earth MOFs: a (micro)spectroscopic
study of active site formation by the controlled transformation of
structural anions},
author = {P Valvekens and D Jonckheere and T De Baerdemaeker and A V Kubarev and M Vandichel and K Hemelsoet and M Waroquier and V Van Speybroeck and E Smolders and D Depla and M B J Roeffaers and D De Vos},
doi = {10.1039/c4sc01731e},
issn = {2041-6520},
year = {2014},
date = {2014-01-01},
journal = {CHEMICAL SCIENCE},
volume = {5},
number = {11},
pages = {4517-4524},
abstract = {A new method has been developed for generating highly dispersed base
sites on metal-organic framework (MOF) lattices. The base catalytic activity of two alkaline earth MOFs, M-2(BTC)(NO3)(DMF) (M = Ba or Sr},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
sites on metal-organic framework (MOF) lattices. The base catalytic activity of two alkaline earth MOFs, M-2(BTC)(NO3)(DMF) (M = Ba or Sr
Speybroeck, Veronique Van; Wispelaere, Kristof De; der Mynsbrugge, Jeroen Van; Vandichel, Matthias; Hemelsoet, Karen; Waroquier, Michel
First principle chemical kinetics in zeolites: the methanol-to-olefin process as a case study Journal Article
In: CHEMICAL SOCIETY REVIEWS, vol. 43, no. 21, pp. 7326-7357, 2014, ISSN: 0306-0012.
@article{ISI:000342908200006,
title = {First principle chemical kinetics in zeolites: the methanol-to-olefin
process as a case study},
author = {Veronique Van Speybroeck and Kristof De Wispelaere and Jeroen Van der Mynsbrugge and Matthias Vandichel and Karen Hemelsoet and Michel Waroquier},
doi = {10.1039/c4cs00146j},
issn = {0306-0012},
year = {2014},
date = {2014-01-01},
journal = {CHEMICAL SOCIETY REVIEWS},
volume = {43},
number = {21},
pages = {7326-7357},
abstract = {To optimally design next generation catalysts a thorough understanding
of the chemical phenomena at the molecular scale is a prerequisite.
Apart from qualitative knowledge on the reaction mechanism, it is also
essential to be able to predict accurate rate constants. Molecular
modeling has become a ubiquitous tool within the field of heterogeneous
catalysis. Herein, we review current computational procedures to
determine chemical kinetics from first principles, thus by using no
experimental input and by modeling the catalyst and reacting species at
the molecular level. Therefore, we use the methanol-to- olefin (MTO)
process as a case study to illustrate the various theoretical concepts.
This process is a showcase example where rational design of the catalyst
was for a long time performed on the basis of trial and error, due to
insufficient knowledge of the mechanism. For theoreticians the MTO
process is particularly challenging as the catalyst has an inherent
supramolecular nature, for which not only the Bronsted acidic site is
important but also organic species, trapped in the zeolite pores, must
be essentially present during active catalyst operation. All these
aspects give rise to specific challenges for theoretical modeling. It is
shown that present computational techniques have matured to a level
where accurate enthalpy barriers and rate constants can be predicted for
reactions occurring at a single active site. The comparison with
experimental data such as apparent kinetic data for well-defined
elementary reactions has become feasible as current computational
techniques also allow predicting adsorption enthalpies with reasonable
accuracy. Real catalysts are truly heterogeneous in a space-and
time-like manner. Future theory developments should focus on extending
our view towards phenomena occurring at longer length and time scales
and integrating information from various scales towards a unified
understanding of the catalyst. Within this respect molecular dynamics
methods complemented with additional techniques to simulate rare events
are now gradually making their entrance within zeolite catalysis. Recent
applications have already given a flavor of the benefit of such
techniques to simulate chemical reactions in complex molecular
environments.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
of the chemical phenomena at the molecular scale is a prerequisite.
Apart from qualitative knowledge on the reaction mechanism, it is also
essential to be able to predict accurate rate constants. Molecular
modeling has become a ubiquitous tool within the field of heterogeneous
catalysis. Herein, we review current computational procedures to
determine chemical kinetics from first principles, thus by using no
experimental input and by modeling the catalyst and reacting species at
the molecular level. Therefore, we use the methanol-to- olefin (MTO)
process as a case study to illustrate the various theoretical concepts.
This process is a showcase example where rational design of the catalyst
was for a long time performed on the basis of trial and error, due to
insufficient knowledge of the mechanism. For theoreticians the MTO
process is particularly challenging as the catalyst has an inherent
supramolecular nature, for which not only the Bronsted acidic site is
important but also organic species, trapped in the zeolite pores, must
be essentially present during active catalyst operation. All these
aspects give rise to specific challenges for theoretical modeling. It is
shown that present computational techniques have matured to a level
where accurate enthalpy barriers and rate constants can be predicted for
reactions occurring at a single active site. The comparison with
experimental data such as apparent kinetic data for well-defined
elementary reactions has become feasible as current computational
techniques also allow predicting adsorption enthalpies with reasonable
accuracy. Real catalysts are truly heterogeneous in a space-and
time-like manner. Future theory developments should focus on extending
our view towards phenomena occurring at longer length and time scales
and integrating information from various scales towards a unified
understanding of the catalyst. Within this respect molecular dynamics
methods complemented with additional techniques to simulate rare events
are now gradually making their entrance within zeolite catalysis. Recent
applications have already given a flavor of the benefit of such
techniques to simulate chemical reactions in complex molecular
environments.
der Voort, Pascal Van; Leus, Karen; Liu, Ying-Ya; Vandichel, Matthias; Speybroeck, Veronique Van; Waroquier, Michel; Biswas, Shyam
Vanadium metal-organic frameworks: structures and applications Journal Article
In: NEW JOURNAL OF CHEMISTRY, vol. 38, no. 5, pp. 1853-1867, 2014, ISSN: 1144-0546.
@article{ISI:000334832200006,
title = {Vanadium metal-organic frameworks: structures and applications},
author = {Pascal Van der Voort and Karen Leus and Ying-Ya Liu and Matthias Vandichel and Veronique Van Speybroeck and Michel Waroquier and Shyam Biswas},
doi = {10.1039/c3nj01130e},
issn = {1144-0546},
year = {2014},
date = {2014-01-01},
journal = {NEW JOURNAL OF CHEMISTRY},
volume = {38},
number = {5},
pages = {1853-1867},
abstract = {This perspective review paper describes the V-containing metal-organic
frameworks that have been developed since the first systematic reports
on MOFs almost 15 years ago. These hybrid crystalline materials,
containing V(III) or V(IV) as metal nodes, show interesting behavior in
oxidation catalysis and gas sorption. A significant amount of papers has
appeared on the use of these structures in gas (hydrocarbon, CO2)
separation. Promising future research and development of V-MOFs is
suggested.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
frameworks that have been developed since the first systematic reports
on MOFs almost 15 years ago. These hybrid crystalline materials,
containing V(III) or V(IV) as metal nodes, show interesting behavior in
oxidation catalysis and gas sorption. A significant amount of papers has
appeared on the use of these structures in gas (hydrocarbon, CO2)
separation. Promising future research and development of V-MOFs is
suggested.
Velazquez, Heriberto Diaz; Garcia, Yara Ruiz; Vandichel, Matthias; Madder, Annemieke; Verpoort, Francis
Water-soluble NHC-Cu catalysts: applications in click chemistry, bioconjugation and mechanistic analysis Journal Article
In: ORGANIC & BIOMOLECULAR CHEMISTRY, vol. 12, no. 46, pp. 9350-9356, 2014, ISSN: 1477-0520.
@article{ISI:000344989700010,
title = {Water-soluble NHC-Cu catalysts: applications in click chemistry,
bioconjugation and mechanistic analysis},
author = {Heriberto Diaz Velazquez and Yara Ruiz Garcia and Matthias Vandichel and Annemieke Madder and Francis Verpoort},
doi = {10.1039/c4ob01350f},
issn = {1477-0520},
year = {2014},
date = {2014-01-01},
journal = {ORGANIC & BIOMOLECULAR CHEMISTRY},
volume = {12},
number = {46},
pages = {9350-9356},
abstract = {Copper(I)-catalyzed 1,3-dipolar cycloaddition of azides and terminal
alkynes (CuAAC), better known as ``click'' reaction, has triggered the
use of 1,2,3-triazoles in bioconjugation, drug discovery, materials
science and combinatorial chemistry. Here we report a new series of
water-soluble catalysts based on N-heterocyclic carbene (NHC)-Cu
complexes which are additionally functionalized with a sulfonate group.
The complexes show superior activity towards CuAAC reactions and display
a high versatility, enabling the production of triazoles with different
substitution patterns. Additionally, successful application of these
complexes in bioconjugation using unprotected peptides acting as DNA
binding domains was achieved for the first time. Mechanistic insight
into the reaction mechanism is obtained by means of state-of-the-art
first principles calculations.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
alkynes (CuAAC), better known as ``click'' reaction, has triggered the
use of 1,2,3-triazoles in bioconjugation, drug discovery, materials
science and combinatorial chemistry. Here we report a new series of
water-soluble catalysts based on N-heterocyclic carbene (NHC)-Cu
complexes which are additionally functionalized with a sulfonate group.
The complexes show superior activity towards CuAAC reactions and display
a high versatility, enabling the production of triazoles with different
substitution patterns. Additionally, successful application of these
complexes in bioconjugation using unprotected peptides acting as DNA
binding domains was achieved for the first time. Mechanistic insight
into the reaction mechanism is obtained by means of state-of-the-art
first principles calculations.
2013
Biswas, Shyam; Vanpoucke, Danny E P; Verstraelen, Toon; Vandichel, Matthias; Couck, Sarah; Leus, Karen; Liu, Ying-Ya; Waroquier, Michel; Speybroeck, Veronique Van; Denayer, Joeri F M; der Voort, Pascal Van
In: JOURNAL OF PHYSICAL CHEMISTRY C, vol. 117, no. 44, pp. 22784-22796, 2013, ISSN: 1932-7447.
@article{ISI:000326845400037,
title = {New Functionalized Metal-Organic Frameworks MIL-47-X (X = -Cl, -Br,
-CH3, -CF3, -OH, -OCH3): Synthesis, Characterization, and CO2 Adsorption
Properties},
author = {Shyam Biswas and Danny E P Vanpoucke and Toon Verstraelen and Matthias Vandichel and Sarah Couck and Karen Leus and Ying-Ya Liu and Michel Waroquier and Veronique Van Speybroeck and Joeri F M Denayer and Pascal Van der Voort},
doi = {10.1021/jp406835n},
issn = {1932-7447},
year = {2013},
date = {2013-11-01},
journal = {JOURNAL OF PHYSICAL CHEMISTRY C},
volume = {117},
number = {44},
pages = {22784-22796},
abstract = {Six new functionalized vanadium hydroxo terephthalates [V-III(OH)(BDC-X)]center dot n(guests) (MIL-47(V-III)-X-AS) (BDC = 1,4-benzenedicarboxylate; X = -Cl, -Br, -CH3, -CF3, -OH, -OCH3; AS =
as-synthesized) along with the parent MIL-47 were synthesized under
rapid microwave-assisted hydrothermal conditions (170 degrees C, 30 min,
150 W). The unreacted H2BDC-X and/or occluded solvent molecules can be
removed by thermal activation under vacuum, leading to the empty-pore
forms of the title compounds (MIL-47(V-IV)-X). Except pristine MIL-47
(+III oxidation state), the vanadium atoms in all the evacuated
functionalized solids stayed in the +IV oxidation state. The phase
purity of the compounds was ascertained by X-ray powder diffraction
(XRPD), diffuse reflectance infrared Fourier transform (DRIFT)
spectroscopy, Raman, thermogravimetric (TG), and elemental analysis. The
structural similarity of the filled and empty-pore forms of the
functionalized compounds with the respective forms of parent MIL-47 was
verified by cell parameter determination from XRPD data. TGA and
temperature-dependent XRPD (TDXRPD) experiments in an air atmosphere
indicate high thermal stability in the 330-385 degrees C range. All the
thermally activated compounds exhibit significant microporosity (S-BET
in the 305-897 m(2) g(-1) range), as verified by the N-2 and CO2
sorption analysis. Among the six functionalized compounds,
MIL-47(V-IV)-OCH3 shows the highest CO2 uptake, demonstrating the
determining role of functional groups on the CO2 sorption behavior. For
this compound and pristine MIL-47(V-IV), Widom particle insertion
simulations were performed based on ab initio calculated crystal
structures. The theoretical Henry coefficients show a good agreement
with the experimental values, and calculated isosurfaces for the local
excess chemical potential indicate the enhanced CO2 affinity is due to
two effects: (i) the interaction between the methoxy group and CO2 and
(ii) the collapse of the MIL-47(V-IV)-OCH3 framework.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
as-synthesized) along with the parent MIL-47 were synthesized under
rapid microwave-assisted hydrothermal conditions (170 degrees C, 30 min,
150 W). The unreacted H2BDC-X and/or occluded solvent molecules can be
removed by thermal activation under vacuum, leading to the empty-pore
forms of the title compounds (MIL-47(V-IV)-X). Except pristine MIL-47
(+III oxidation state), the vanadium atoms in all the evacuated
functionalized solids stayed in the +IV oxidation state. The phase
purity of the compounds was ascertained by X-ray powder diffraction
(XRPD), diffuse reflectance infrared Fourier transform (DRIFT)
spectroscopy, Raman, thermogravimetric (TG), and elemental analysis. The
structural similarity of the filled and empty-pore forms of the
functionalized compounds with the respective forms of parent MIL-47 was
verified by cell parameter determination from XRPD data. TGA and
temperature-dependent XRPD (TDXRPD) experiments in an air atmosphere
indicate high thermal stability in the 330-385 degrees C range. All the
thermally activated compounds exhibit significant microporosity (S-BET
in the 305-897 m(2) g(-1) range), as verified by the N-2 and CO2
sorption analysis. Among the six functionalized compounds,
MIL-47(V-IV)-OCH3 shows the highest CO2 uptake, demonstrating the
determining role of functional groups on the CO2 sorption behavior. For
this compound and pristine MIL-47(V-IV), Widom particle insertion
simulations were performed based on ab initio calculated crystal
structures. The theoretical Henry coefficients show a good agreement
with the experimental values, and calculated isosurfaces for the local
excess chemical potential indicate the enhanced CO2 affinity is due to
two effects: (i) the interaction between the methoxy group and CO2 and
(ii) the collapse of the MIL-47(V-IV)-OCH3 framework.
Vandichel, Matthias; Vermoortele, Frederik; Cottenie, Stijn; Vos, Dirk E De; Waroquier, Michel; Speybroeck, Veronique Van
Insight in the activity and diastereoselectivity of various Lewis acid catalysts for the citronellal cyclization Journal Article
In: JOURNAL OF CATALYSIS, vol. 305, pp. 118-129, 2013, ISSN: 0021-9517.
@article{ISI:000322501000013,
title = {Insight in the activity and diastereoselectivity of various Lewis acid
catalysts for the citronellal cyclization},
author = {Matthias Vandichel and Frederik Vermoortele and Stijn Cottenie and Dirk E De Vos and Michel Waroquier and Veronique Van Speybroeck},
doi = {10.1016/j.jcat.2013.04.017},
issn = {0021-9517},
year = {2013},
date = {2013-09-01},
journal = {JOURNAL OF CATALYSIS},
volume = {305},
pages = {118-129},
abstract = {Industrial (-)-menthol production generally relies on the hydrogenation
of (-)-isopulegol, which is in turn produced with high selectivity by
cyclization of (+)-citronellal. This paper uses a combined theoretical
and experimental approach to study the activity and selectivity of three
Lewis acid catalysts for this reaction, namely ZnBr2, aluminum
tris(2,6-diphenylphenoxide) (ATPH), and the heterogeneous metal-organic framework Cu3BTC2 (BTC = benzene-1,3,5-tricarboxylate). ATPH is a strong
Lewis acid homogeneous catalyst with bulky ligands which provides very
high selectivities for the desired stereoisomer (>99%). The performance
of the catalysts was evaluated as a function of temperature, which
revealed that a higher catalyst activity allows working at lower
temperatures and improves the selectivity for isopulegol. The
selectivity distribution is kinetically driven for ZnBr2 and ATPH. The
theoretical selectivity distributions rely on the determination of an
extensive set of diastereomeric transition states, for which the
differences in free energy have been calculated using a complementary
set of ab initio techniques. Given the sensitivity of the selectivity to
small Gibbs free-energy differences, the agreement between experimental
and theoretical selectivities is satisfactory. On basis of the obtained
insights, rational design of new catalysts may be obtained. As proof of
concept, the hypothetical Cu-3(BTC-(NO2)(3))(2) Lewis catalyst - in
which each phenyl hydrogen of the BTC ligand is replaced by a nitro
group - is predicted to be very selective. (C) 2013 Elsevier Inc. All
rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
of (-)-isopulegol, which is in turn produced with high selectivity by
cyclization of (+)-citronellal. This paper uses a combined theoretical
and experimental approach to study the activity and selectivity of three
Lewis acid catalysts for this reaction, namely ZnBr2, aluminum
tris(2,6-diphenylphenoxide) (ATPH), and the heterogeneous metal-organic framework Cu3BTC2 (BTC = benzene-1,3,5-tricarboxylate). ATPH is a strong
Lewis acid homogeneous catalyst with bulky ligands which provides very
high selectivities for the desired stereoisomer (>99%). The performance
of the catalysts was evaluated as a function of temperature, which
revealed that a higher catalyst activity allows working at lower
temperatures and improves the selectivity for isopulegol. The
selectivity distribution is kinetically driven for ZnBr2 and ATPH. The
theoretical selectivity distributions rely on the determination of an
extensive set of diastereomeric transition states, for which the
differences in free energy have been calculated using a complementary
set of ab initio techniques. Given the sensitivity of the selectivity to
small Gibbs free-energy differences, the agreement between experimental
and theoretical selectivities is satisfactory. On basis of the obtained
insights, rational design of new catalysts may be obtained. As proof of
concept, the hypothetical Cu-3(BTC-(NO2)(3))(2) Lewis catalyst - in
which each phenyl hydrogen of the BTC ligand is replaced by a nitro
group - is predicted to be very selective. (C) 2013 Elsevier Inc. All
rights reserved.
Vermoortele, Frederik; Bueken, Bart; Bars, Gaelle Le; de Voorde, Ben Van; Vandichel, Matthias; Houthoofd, Kristof; Vimont, Alexandre; Daturi, Marco; Waroquier, Michel; Speybroeck, Veronique Van; Kirschhock, Christine; Vos, Dirk E De
Synthesis Modulation as a Tool To Increase the Catalytic Activity of Metal-Organic Frameworks: The Unique Case of UiO-66(Zr) Journal Article
In: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 135, no. 31, pp. 11465-11468, 2013, ISSN: 0002-7863.
@article{ISI:000323019400014,
title = {Synthesis Modulation as a Tool To Increase the Catalytic Activity of
Metal-Organic Frameworks: The Unique Case of UiO-66(Zr)},
author = {Frederik Vermoortele and Bart Bueken and Gaelle Le Bars and Ben Van de Voorde and Matthias Vandichel and Kristof Houthoofd and Alexandre Vimont and Marco Daturi and Michel Waroquier and Veronique Van Speybroeck and Christine Kirschhock and Dirk E De Vos},
doi = {10.1021/ja405078u},
issn = {0002-7863},
year = {2013},
date = {2013-08-01},
journal = {JOURNAL OF THE AMERICAN CHEMICAL SOCIETY},
volume = {135},
number = {31},
pages = {11465-11468},
abstract = {The catalytic activity of the zirconium terephthalate UiO-66(Zr) can be
drastically increased by using a modulation approach. The combined use
of trifluoroacetic acid and HCl during the synthesis results in a highly
crystalline material, with partial substitution of terephthalates by
trifluoroacetate. Thermal activation of the material leads not only to
dehydroxylation of the hexanuclear Zr cluster but also to post-synthetic
removal of the trifluoroacetate groups, resulting in a more open
framework with a large number of open sites. Consequently, the material
is a highly active catalyst for several Lewis acid catalyzed reactions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
drastically increased by using a modulation approach. The combined use
of trifluoroacetic acid and HCl during the synthesis results in a highly
crystalline material, with partial substitution of terephthalates by
trifluoroacetate. Thermal activation of the material leads not only to
dehydroxylation of the hexanuclear Zr cluster but also to post-synthetic
removal of the trifluoroacetate groups, resulting in a more open
framework with a large number of open sites. Consequently, the material
is a highly active catalyst for several Lewis acid catalyzed reactions.
Ghysels, An; Vanduyfhuys, Louis; Vandichel, Matthias; Waroquier, Michel; Speybroeck, Veronique Van; Smit, Berend
On the Thermodynamics of Framework Breathing: A Free Energy Model for Gas Adsorption in MIL-53 Journal Article
In: JOURNAL OF PHYSICAL CHEMISTRY C, vol. 117, no. 22, pp. 11540-11554, 2013, ISSN: 1932-7447.
@article{ISI:000320214800011,
title = {On the Thermodynamics of Framework Breathing: A Free Energy Model for
Gas Adsorption in MIL-53},
author = {An Ghysels and Louis Vanduyfhuys and Matthias Vandichel and Michel Waroquier and Veronique Van Speybroeck and Berend Smit},
doi = {10.1021/jp311601q},
issn = {1932-7447},
year = {2013},
date = {2013-06-01},
journal = {JOURNAL OF PHYSICAL CHEMISTRY C},
volume = {117},
number = {22},
pages = {11540-11554},
abstract = {When adsorbing guest molecules, the porous metal-organic framework
MIL-53(Cr) may vary its cell parameters drastically while retaining its
crystallinity. A first approach to the thermodynamic analysis of this
``framework breathing'' consists of comparing the osmotic potential in
two distinct shapes only (large-pore and narrow-pore). In this paper, we
propose a generic parametrized free energy model including three
contributions: host free energy, guest-guest interactions, and
host-guest interaction. Free energy landscapes may now be constructed
scanning all shapes and any adsorbed amount of guest molecules. This
allows us to determine which shapes are the most stable states for
arbitrary combinations of experimental control parameters, such as the
adsorbing gas chemical potential, the external pressure, and the
temperature. The new model correctly reproduces the structural
transitions along the CO2 and CH4 isotherms. Moreover, our model
successfully explains the adsorption versus desorption hysteresis as a
consequence of the creation, stabilization, destabilization, and
disappearance of a second free energy minimum under the assumptions of a
first-order phase transition and collective behavior. Our general
thermodynamic description allows us to decouple the gas chemical
potential mu and mechanical pressure P as two independent thermodynamic
variables and predict the complete (mu, P) phase diagram for CO2
adsorption in MIL-53(Cr). The free energy model proposed here is an
important step toward a general thermodynamics description of flexible
metal-organic frameworks.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
MIL-53(Cr) may vary its cell parameters drastically while retaining its
crystallinity. A first approach to the thermodynamic analysis of this
``framework breathing'' consists of comparing the osmotic potential in
two distinct shapes only (large-pore and narrow-pore). In this paper, we
propose a generic parametrized free energy model including three
contributions: host free energy, guest-guest interactions, and
host-guest interaction. Free energy landscapes may now be constructed
scanning all shapes and any adsorbed amount of guest molecules. This
allows us to determine which shapes are the most stable states for
arbitrary combinations of experimental control parameters, such as the
adsorbing gas chemical potential, the external pressure, and the
temperature. The new model correctly reproduces the structural
transitions along the CO2 and CH4 isotherms. Moreover, our model
successfully explains the adsorption versus desorption hysteresis as a
consequence of the creation, stabilization, destabilization, and
disappearance of a second free energy minimum under the assumptions of a
first-order phase transition and collective behavior. Our general
thermodynamic description allows us to decouple the gas chemical
potential mu and mechanical pressure P as two independent thermodynamic
variables and predict the complete (mu, P) phase diagram for CO2
adsorption in MIL-53(Cr). The free energy model proposed here is an
important step toward a general thermodynamics description of flexible
metal-organic frameworks.