Article
Chemistry, Physical
Thulani M. Nyathi, Mohamed Fadlalla, Nico Fischer, Andrew P. E. York, Ezra J. Olivier, Emma K. Gibson, Peter P. Wells, Michael Claeys
Summary: The study investigated the impact of different supports on the catalytic performance and phase stability of Co3O4 nanoparticles during CO-PrOx. Results showed that weak nanoparticle-support interactions (as in Co3O4/ZrO2) favored high CO oxidation activity, while stronger interactions (as in Co3O4/Al2O3) helped minimize Co-0 and CH4 formation. The study highlights the bi-functional role supports play in CO-PrOx, enhancing catalytic performance and improving the phase stability of Co3O4.
APPLIED CATALYSIS B-ENVIRONMENTAL
(2021)
Article
Chemistry, Physical
Abheek Datta, Shubham Deolka, Pawan Kumar, Zakaria Ziadi, Toshio Sasaki, Stephan Steinhauer, Vidyadhar Singh, Nan Jian, Eric Danielson, Alexander James Porkovich
Summary: The interaction between oxide supports and noble metal nanoparticles is a key area of research in catalysis, with mechanisms such as oxygen spillover, metal support interactions, and charge transfer playing important roles in enhancing catalytic activity. This study focused on the migration of oxygen across the Pd NP-CuO NW interface, revealing that oxygen enters the Pd NP lattice from the Pd-CuO interface via amorphization of the NP. Compared to Pd supported on a non-reducible substrate, it was found that the oxidation and reduction of Pd on CuO forms a PdO NP surface full of Pd-PdO sites, allowing for synergistic effects in the oxidation and hydrogenation of organic species.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Nanoscience & Nanotechnology
W. Al Zoubi, N. Nashrah, R. A. K. Putri, A. W. Allaf, B. Assfour, Y. G. Ko
Summary: In this study, a novel synthesis strategy was reported to achieve low-temperature plasma-induced strong metal-support interactions (SMSIs) on a MgO-supported MAg (M = Cu, Fe, or Ni) system using an electric field at a localized interface. The resulting MAg@MgO catalysts, consisting of uniformly distributed intermetallic nanoparticles and a unique porous support, exhibited high activity and excellent reusability.
MATERIALS TODAY NANO
(2022)
Article
Chemistry, Physical
Christos Papadopoulos, Konstantinos Kappis, Joan Papavasiliou, John Vakros, Aspasia Antonelou, Wojciech Gac, Haibin Li, George Avgouropoulos
Summary: CuCe mixed oxides are commonly used for preferential CO oxidation in the purification of hydrogen-rich gas stream. This study investigated the synthesis of various ceria supports and the preparation of CuCe mixed-oxide catalysts. It found that modifying the hydrothermal parameters can tune the properties of the supports, leading to highly active and selective catalysts. The nature of the reduced copper species and the optimum content in oxygen vacancies play crucial roles in the catalytic performance.
Article
Engineering, Environmental
Menglan Xiao, Xiaolin Yu, Yucong Guo, Maofa Ge
Summary: The study focused on the electronic metal-support interaction to enhance the catalytic performance of Pt@Co3O4 catalysts in toluene degradation. The catalyst showed excellent activity, water resistance, and long-term stability. Surface oxygen species played a crucial role in toluene degradation and could efficiently be replenished by gaseous oxygen.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2022)
Article
Chemistry, Physical
Raziyeh Jokar, Seyed Mehdi Alavi, Mehran Rezaei, Ehsan Akbari
Summary: The study found that the 10wt% CuO/MnO2 catalyst exhibited the best catalytic performance in CO preferential oxidation reaction, attributed to the synergistic interaction between copper and manganese. However, adding CO2 and/or H2O to the feedstock decreased the catalyst performance.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2021)
Article
Chemistry, Physical
Samane Gholami, Seyed Mehdi Alavi, Mehran Rezaei
Summary: In this study, a series of Cr2O3-Al2O3 powders were synthesized as carriers for nickel catalysts in CO2 methanation, showing improved catalytic performance with increased Cr2O3 content. The 15 wt%Ni/Cr2O3 catalyst exhibited high CO2 conversion and CH4 selectivity, and the CO2 conversion was found to increase with higher H2/CO2 molar ratios and lower gas hourly space velocities. Additionally, increasing calcination temperature led to lower CO2 conversion, while the catalyst showed high stability in the methanation reaction.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2021)
Article
Chemistry, Physical
Lindokuhle B. Ngema, Majid D. Farahani, Shaine Raseale, Nico Fischer, Abdul S. Mohamed, Sooboo Singh, Holger B. Friedrich
Summary: Employing a reduction-oxidation pretreatment successfully modified the Co3O4 | ZrO2 catalyst surface, leading to improved CO oxidation activity. The restructuring of Co3O4 to CoO species on the ZrO2 surface formed a highly active Co3O4-CoO | ZrO2 interface, resulting in enhanced CO2 desorption sites and CO oxidation activity. The findings highlight the importance of surface modification for improving CO preferential oxidation activity.
SURFACES AND INTERFACES
(2023)
Article
Energy & Fuels
Wanjun Zhao, Hui Dang, Lijun Yue, Yongzhao Wang, Ruifang Wu, Haitao Li, Yongxiang Zhao
Summary: A series of Pd-Cu-xSn/Al2O3 catalysts with low tin content were prepared and used for low-temperature CO preferential oxidation (CO-PROX) in H2-rich stream. The addition of Sn promoted the interaction between Sn species and PdCu/Al2O3, improving the stability of active Cu2Cl(OH)3 species. The doping of Sn also hindered the reduction of active Pd species and facilitated the reoxidation of Cu+ species.
Article
Chemistry, Physical
Ireneusz Kocemba, Izabela Smiechowicz, Marcin Jedrzejczyk, Jacek Rogowski, Jacek Michal Rynkowski
Summary: The concept of very strong metal-support interactions (VSMSI) was defined to explain the high catalytic activity of the 1%Pt/Al2O3 catalyst. Through various characterization methods, it was claimed that nonstoichiometric platinum species formed after high temperature reduction strongly anchor to the Al2O3 surface, acting as oxygen adsorption sites.
Article
Materials Science, Multidisciplinary
Xiaodan Chen, Heleen van Gog, Marijn A. van Huis
Summary: Nanoparticles of Co3O4 and CoO exhibit significant chemical and magnetic properties, with experiments and calculations revealing an ordered transformation at high temperatures, characterized by a low interface energy and a substantial ferromagnetic moment at the interface.
JOURNAL OF MATERIALS CHEMISTRY C
(2021)
Article
Nanoscience & Nanotechnology
Zhang Liu, Jiaqiang Yang, Yanwei Wen, Yuxiao Lan, Limin Guo, Xi Chen, Kun Cao, Rong Chen, Bin Shan
Summary: This study investigates the mechanism of CO PROX reaction on Co3O4 supported single Pt atom through first-principles based microkinetic analysis. The research finds that H2 prereduction treatment effectively mitigates the CO poisoning effect and surface H atoms assist in improving the activity and selectivity at low temperatures.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Physical
Varvara Lagunova, Evgeny Filatov, Pavel Plyusnin, Gennady Kostin, Artem Urlukov, Dmitry Potemkin, Sergey Korenev
Summary: The properties of Pt-based catalysts can be modified by adding a second metal and forming an alloy or metal-oxide interface. This study investigated the effect of Cr, Mo, and W doping on the performance of Pt in CO TOX and PROX reactions. [Pt(NH3)4]MO4 (M = Mo, W) salts and solid solutions [Pt(NH3)4](M'O4)x(M00O4)1-x (M' = Cr, Mo, W; M'' = Cr, Mo, W) were used as catalyst precursors. They were synthesized, characterized, and their thermal properties were analyzed in an oxidative atmosphere. The decomposition process was found to be multistage, resulting in the formation of platinum and the corresponding base metal oxides (Cr/Mo/W).
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Chemistry, Multidisciplinary
Hai Wang, Xue Dong, Yu Hui, Yiming Niu, Bingsen Zhang, Lujie Liu, Ji Cao, Mizuho Yabushita, Yoshinao Nakagawa, Keiichi Tomishige, Yucai Qin, Lijuan Song, Jianping Xiao, Liang Wang, Feng-Shou Xiao
Summary: A new form of strong metal-support interaction (SMSI) has been achieved by creating oxygen-saturated overlayers on Au/TiO2 catalyst through steaming treatment, which demonstrates improved stability compared to classical SMSI. The study shows that the strong interaction between the TiOxHy (x ≥ 2) species and Au surface causes the migration of TiO2 to encapsulate Au nanoparticles. The oxygen-saturated oxide overlayers exhibit stability in oxidative, reductive, and humid atmospheres, providing enhanced performance for metal nanoparticle catalysts under various reaction conditions, surpassing classical SMSI.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Engineering, Chemical
Chuangchuang Yang, Qiaoling Dai, Anpeng Hu, Hui Yuan, Qinghe Yang
Summary: A new sulfurized hydrodesulfurization catalyst was synthesized, which showed improved desulfurization activity due to the enhanced metal-support interactions. The catalyst's structure and performance were evaluated by studying the annealing temperature and the type of Al2O3 precursor.
Article
Chemistry, Inorganic & Nuclear
Peter P. Edwards, Nicholas C. Pyper, Xiangyu Jie, Daniel R. Slocombe, C. Richard A. Catlow, M. Saiful Islam, Peter J. Dobson
Summary: This passage discusses the contributions and observations of Miguel Alario-Franco in the field of high-temperature superconductivity. He highlights the need for a new theme to unify chemistry and physics in this field and reviews recent research advances.
JOURNAL OF SOLID STATE CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Jamal Abdul Nasir, Jingcheng Guan, Thomas W. Keal, Alec W. Desmoutier, You Lu, Andrew M. Beale, C. Richard A. Catlow, Alexey A. Sokol
Summary: This study investigates the NH3-SCR reaction mechanism on Cu-CHA catalyst using QM/MM technique and examines the effects of solvent on the reactivity of active Cu species. The results reveal that solvent promotes the oxidation component of the NH3-SCR cycle but inhibits the reduction component. Experimental and calculated spectroscopic analysis identify the existence of important species such as Cu-nitrate and Cu-nitrosamine. These findings contribute to a detailed understanding of the NH3-SCR kinetics.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Physical
Richard J. Lewis, Kenji Ueura, Xi Liu, Yukimasa Fukuta, Tian Qin, Thomas E. Davies, David J. Morgan, Alex Stenner, James Singleton, Jennifer K. Edwards, Simon J. Freakley, Christopher J. Kiely, Liwei Chen, Yasushi Yamamoto, Graham J. Hutchings
Summary: The in-situ production of H2O2 enables the ammoximation of ketones to oximes, providing a feasible alternative for industrial-scale production, especially for synthesizing cyclohexanone oxime as a key precursor to Nylon-6. By using a bifunctional catalyst consisting of Pd-based bimetallic nanoparticles immobilized onto a TS-1 carrier, the considerable condition gap between the direct synthesis of H2O2 and ketone ammoximation can be bridged. The formation of PdAu nanoalloys is crucial for achieving high reactivity and catalytic stability, with the monometallic Pd analogue being optimal.
Article
Chemistry, Physical
Tao Tong, Mark Douthwaite, Lu Chen, Rebecca Engel, Matthew B. Conway, Wanjun Guo, Xin-Ping Wu, Xue-Qing Gong, Yanqin Wang, David J. Morgan, Thomas Davies, Christopher J. Kiely, Liwei Chen, Xi Liu, Graham J. Hutchings
Summary: The physicochemical properties of Pt/CeO2 catalysts were varied to investigate their impact on the hydrogen-borrowing amination of alcohols. It was found that the Pt precursor and CeO2 support properties strongly influenced catalytic performance. The most active catalyst exhibited linearly structured Pt species, which were more effective for the rate-determining step of cyclopentanol dehydrogenation compared to Pt clusters and nanoparticles. This study not only provides insights into desirable catalytic properties for hydrogen-borrowing amination but also has broader relevance to related fields.
Article
Chemistry, Physical
Isaac T. T. Daniel, Liang Zhao, Donald Bethell, Mark Douthwaite, Samuel Pattisson, Richard J. J. Lewis, Ouardia Akdim, David J. J. Morgan, Steven McIntosh, Graham J. J. Hutchings
Summary: Recent studies have shown that the rate of catalytic alcohol and formyl dehydrogenation in bimetallic Au-Pd systems is closely related to the rate of oxygen reduction. In this study, the rate enhancement resulting from the coupling of these two processes is evaluated for the oxidative dehydrogenation of 5-hydroxymethylfurfural. By changing the molar ratio of Au and Pd in a physical mixture of carbon-supported catalysts, the influence of the ratio on the activity is explored. It is found that the activity of the bimetallic system exceeds the combined activity of the monometallic analogues. The kinetic analysis of the system predicts the locations of the maxima in activity for both monometallic and bimetallic systems. The accuracy of the model provides further evidence and understanding of cooperative redox enhancement effects observed in bimetallic, heterogeneous catalytic systems.
CATALYSIS SCIENCE & TECHNOLOGY
(2023)
Article
Chemistry, Physical
David J. J. Morgan
Summary: Standard X-ray photoelectron spectroscopy (XPS) analysis, commonly considered non-destructive, can actually cause significant changes to the analysed area due to the interaction of X-ray photons and subsequent electron cascade. This XPS Insights paper provides a brief overview, supported by specific examples and experimental advice, on assessing and minimizing damage during analysis.
SURFACE AND INTERFACE ANALYSIS
(2023)
Article
Chemistry, Physical
Liang Zhao, Ouardia Akdim, Xiaoyang Huang, Kai Wang, Mark Douthwaite, Samuel Pattisson, Richard J. Lewis, Runjia Lin, Bingqing Yao, David J. Morgan, Greg Shaw, Qian He, Donald Bethell, Steven McIntosh, Christopher J. Kiely, Graham J. Hutchings
Summary: The aerobic oxidation of alcohols and aldehydes over supported heterogeneous catalysts involves dehydrogenation and oxygen reduction processes. The cooperative redox enhancement (CORE) effect, where independent active sites catalyze the processes and electron transport occurs between the catalysts, can greatly influence catalyst design. The Au/Pd ratio used in physical mixtures of monometallic catalysts and phase-separated bimetallic catalysts significantly affects the degree to which CORE effects promote alcohol oxidation. Furthermore, the roles of Au and Pd in this coupled system are found to be interchangeable, potentially due to the relative rates of the coupled reactions and the influence of physical properties. This deeper understanding of CORE factors is an important development in bimetallic catalysis.
Editorial Material
Multidisciplinary Sciences
Richard Catlow
ROYAL SOCIETY OPEN SCIENCE
(2023)
Article
Chemistry, Physical
Wijnand Marquart, Michael Claeys, Nico Fischer
Summary: The CO2-assisted oxidative dehydrogenation reaction shows potential as a sustainable alternative for the production of light olefins. This study investigates the effect of reaction temperature on the performance of silica supported molybdenum carbide nanoparticles. The results show an increase in ethylene selectivity with reaction temperature, suggesting an oxidation/re-carburization mechanism rather than prevention of oxidation.
APPLIED CATALYSIS A-GENERAL
(2023)
Article
Environmental Sciences
Chibambila Simbeye, Caitlin Courtney, Prithvi Simha, Nico Fischer, Dyllon G. Randall
Summary: Human urine contributes a significant amount of phosphorus in domestic wastewater, and decentralized sanitation systems can be used to recover this phosphorus. This study found that the type of urine and the Fe:P molar ratio affected the yield and purity of vivianite, while the iron salt used and reaction temperature did not. The pH of the urine had the most significant impact on the solubility of vivianite. Overall, this research contributes to the knowledge on phosphorus recovery from wastewater.
SCIENCE OF THE TOTAL ENVIRONMENT
(2023)
Article
Nanoscience & Nanotechnology
Zijuan Xie, John Buckeridge, C. Richard A. Catlow, Anping Zhang, Thomas W. Keal, Paul Sherwood, You Lu, Scott M. Woodley, Alexey A. Sokol
Summary: In GaN:Mg, compensation of the Mg-Ga acceptor by nitrogen vacancies (V-N) and Mg interstitials (Mg-i) can be overcome by the formation of two kinds of Mg-rich complexes: one containing V-N and the other containing only Mg-Ga and Mg-i. These complexes not only neutralize V-N and Mg-i, but also form better complex acceptors with lower formation energies and smaller hole localization energies than isolated Mg-Ga. Our findings provide insights into the different doping behaviors observed in samples grown by different methods.
Article
Multidisciplinary Sciences
M. I. Fadlalla, R. Mohamed, D. Susac, T. M. Nyathi, S. Blair, M. Claeys, E. van Steen, P. Kooyman, J. C. Q. Fletcher, N. Fischer
Summary: One of the biggest global challenges today is providing affordable, green, sustainable energy to a growing population. Scientists and engineers are working on developing innovative technologies, such as the Power-to-X (PtX) process, which uses renewable energy, water, and captured CO2 to produce green hydrogen, liquid hydrocarbon fuels, and chemicals. These alternative technologies are important solutions, especially for sectors that are difficult to decarbonize.
SCIENTIFIC AFRICAN
(2023)
Article
Chemistry, Physical
Madita Einemann, Simon Haida, Nico Fischer, Nattawut Osakoo, Jatuporn Wittayakun, Frank Roessner
Summary: The role of cobalt chloride hexahydrate as a precursor of cobalt bulk catalysts was investigated for the Fischer-Tropsch reaction. Different oxygen-containing cobalt compounds were detected through in situ DRIFTS, in situ XANES, in situ XRD, and inverse TPR techniques. The reaction network of cobalt chloride transformation was discussed, taking into account the back mixing in different geometries of measuring cells. The choice of catalyst activation procedure is important for the formation of cobalt oxide and subsequent activity in the Fischer-Tropsch reaction.
CATALYSIS SCIENCE & TECHNOLOGY
(2023)
Article
Chemistry, Physical
Lei Zhu, C. Richard A. Catlow, Qing Hou, Xingfan Zhang, John Buckeridge, Alexey A. Sokol
Summary: In this study, an empirical interatomic force field model consistent with lattice energy was derived for wurtzite AlN, which can predict a wide range of physical and defect properties accurately. The novel N3- interstitialcy configuration was found to have lower energy compared to the octahedral-channel-centred counterpart. With the assistance of QM/MM method, the model can accurately predict the VBM level (-7.35 eV) in line with previous experimental measurements. Moreover, the migration mechanisms and energy barriers of the main intrinsic defects were investigated.
JOURNAL OF MATERIALS CHEMISTRY A
(2023)
Article
Chemistry, Physical
Thulani M. Nyathi, Mohamed I. Fadlalla, Nico Fischer, Andrew P. E. York, Ezra J. Olivier, Emma K. Gibson, Peter P. Wells, Michael Claeys
Summary: Co3O4 nanoparticles were supported on different TiO2 polymorphs and their catalytic performance in CO-PrOx was evaluated. Supporting Co3O4 on P25 resulted in the highest CO conversion to CO2 (72.7%), while rutile and anatase showed lower conversions (60.7% and 51.5% respectively). The reduction of Co3O4 was highest on P25 and lowest on anatase, with different crystal phases of Co-0 observed. Furthermore, the presence of different TiO2 polymorphs influenced the formation of undesired CH4 over Co-0 nanoparticles.
CATALYSIS SCIENCE & TECHNOLOGY
(2023)