Richard Catlow

Crystal structure prediction from first principles

The prediction of structure at the atomic level is one of the most fundamental challenges in condensed matter science. Here we survey the current status of the field and consider recent developments in methodology, paying particular attention to approaches for surveying energy landscapes. We illustrate the current state of the art in this field with topical applications to inorganic, especially microporous solids, and to molecular crystals; we also look at applications to nanoparticulate structures. Finally, we consider future directions and challenges in the field.

Experimental and computational studies of ZnS nanostructures

We review the experimental and computational studies of nanoparticulate ZnS, a system that has received much attention recently. We describe in detail how the nanoparticle structures evolve with increasing size. The results of the computational studies reveal intriguing families of structures based on spheroids, which have the greater stability for clusters with less than 50 ZnS pairs. More complex structures are predicted for larger systems, such as double bubbles, BCT nanoparticles and nanotubes.

Reactivities study of titanium sites in titanosilicate frameworks by in situ XANES

This study focused on the study of titanium sites, their local structure and reactivities in nanoporous titanosilicates frameworks by using in situ X-ray absorption spectroscopy. XANES provides the information on the oxidation state of the titanium species as well as their change in coordination geometry during de- and re-hydration. Results from in situ XANES studies shows that TS-1 is much more hydrophobic than TiAl or TiFe systems. Pre-edge features of Ti K-edge XANES spectra of these materials also suggested that TiIV is the dominant Ti coordination in dehydrated system whilst TiVI is the dominant in the re-hydrated one.

25 Computer modelling of inorganic materials

Computer simulation has, over the last thirty years, developed into a new branch of science which links fundamental theory with experiment on complex systems. Simulation techniques are now used in all areas of physical, biological and engineering sciences. But in no field has the impact been greater than in Chemistry. Computational techniques can routinely calculate, with high accuracy, the structures and properties of complex molecules; polymer (especially biomolecular) modelling is a well established if challenging field; modelling is an indispensable tool in contemporary studies of liquids; and in solid state chemistry, as this review will show, simulation techniques are increasingly integrated with experimental synthetic and characterization studies.

In Situ XAS of the Solvothermal Decomposition of Dithiocarbamate Complexes

An in situ XAS study of the solvothermal decomposition of iron and nickel dithiocarbamate complexes was performed in order to gain understanding of the decomposition mechanisms. This work has given insight into the steps involved in the decomposition, showing variation in reaction pathways between the iron and nickel dithiocarbamates, and the non-innocent role of oleylamine as the solvent and capping agent in the reaction.

Ab initio investigation of O2 Adsorption on Ca-Doped LaMnO3 Cathodes in Solid Oxide Fuel Cells

We present a Hubbard-corrected density functional theory (DFT+U) study of the adsorption and reduction reactions of oxygen on the pure and 25% Ca-doped LaMnO3 (LCM25) {100} and {110} surfaces. The effect of oxygen vacancies on the adsorption characteristics and energetics has also been investigated. Our results show that the O2 adsorption/reduction process occurs through the formation of superoxide and peroxide intermediates, with the Mn sites found to be generally more active than the La sites. The LCM25{110} surface is found to be more efficient for O2 reduction than the LCM25{100} surface due to its stronger adsorption of O2, with the superoxide and peroxide intermediates shown to be energetically more favorable at the Mn sites than at the Ca sites. Moreover, oxygen vacancy defect sites on both the {100} and {110} surfaces are shown to be more efficient for O2 reduction, as reflected in the higher adsorption energies calculated on the defective surfaces compared to the perfect surfaces. We show from Löwdin population analysis that the O2 adsorption on the pure and 25% Ca-doped LaMnO3 surfaces is characterized by charge transfer from the interacting surface species into the adsorbed oxygen πg orbital, which results in weakening of the O-O bonds and its subsequent reduction. The elongated O-O bonds were confirmed via vibrational frequency analysis.

Defect formation in In2O3 and SnO2: a new atomistic approach based on accurate lattice energies

We present a consistent interatomic force field for indium sesquioxide (In2O3) and tin dioxide (SnO2) that has been derived to reproduce lattice energies and, consequently, the oxygen vacancy formation energies in the respective binary compounds. The new model predicts the dominance of Frenkel-type disorder in SnO2 and In2O3, in good agreement with ab initio defect calculations. The model is extended to include free electron and hole polarons, which compete with charged point defects to maintain charge neutrality in a defective crystal. The stability of electrons and instability of holes with respect to point defect formation rationalises the efficacy of n-type doping in tin doped indium oxide (ITO), a widely employed transparent conducting oxide in optoelectronic applications. We investigate the clustering of Sn substitutional and oxygen interstitial sites in ITO, finding that the dopants substitute preferentially on the cation crystallographic d site in the bixbyite unit cell, in agreement with experiment. The force field described here provides a useful avenue for the investigation of the defect properties of extended transparent conducting oxide systems, including solid solutions.

The challenges of characterising nanoparticulate catalysts: general discussion

Rosa Arrigo, Kassim Badmus, Francesca Baletto, Maurits Boeije, Michael Bowker, Katharina Brinkert, Aram Bugaev, Valerii Bukhtiyarov, Michele Carosso, Richard Catlow, Revana Chanerika, Philip R. Davies, Wilke Dononelli, Hans-Joachim Freund, Cynthia Friend, Simone Gallarati, Bruce Gates, Alexander Genest, Emma K. Gibson, Justin Hargreaves, Stig Helveg, Haoliang Huang, Graham Hutchings, Nicola Irvine, Roy Johnston, Stanley Lai, Carlo Lamberti, Joseph Macginley, David Marchant, Toru Murayama, Rene Nome, Yaroslav Odarchenko, Jonathan Quinson, Scott Rogers, Andrea Russell, Said Said, Paul Sermon, Parag Shah, Sabrina Simoncelli, Katerina Soulantica, Federico Spolaore, Bob Tooze, Laura Torrente-Murciano, Annette Trunschke, David Willock and Jiaguang Zhang

Application of new nanoparticle structures as catalysts: general discussion

Baletto, Francesca, Boeije, Maurits, Bordet, Alexis, Brinkert, Katharina, Catlow, C. Richard A., Davies, Josh, Dononelli, Wilke, Freund, Hans-Joachim, Friend, Cynthia, Gates, Bruce, Genest, Alexander, Guan, Shaoliang, Hardacre, Christopher, Hargreaves, Justin, Huang, Haoliang, Hutchings, Graham J., Johnston, Roy, Lai, Stanley, Lamberti, Carlo, Marbaix, Julien, Miranda, Caetano Rodrigues, Nome, Rene, Peron, Jennifer, Quinson, Jonathan, Richards, Nia, Roesch, Notker, Russell, Andrea, Said, Said, Selvam, Parasuraman, Sermon, Paul, Shozi, Mzamo, Skylaris, Chris-Kriton, Spolaore, Federico, Walkerdine, James, Whiston, Keith and Willock, David 2018. Application of new nanoparticle structures as catalysts: general discussion. Faraday Discussions 208 , pp. 575-593. 10.1039/C8FD90016G file

Modern developments in catalysis

The UK Catalysis Hub is a consortium of universities working together on fundamental and applied research to find out how catalysts work and to improve their effectiveness. The contribution of catalysis to manufacturing contributes to almost 40% of global GDP, making development and innovation within the field integral to industry. Modern Developments in Catalysis provides a review of current research and practise on catalysis, focussing on five main themes: catalysis design, environmental catalysis, catalysis and energy, chemical transformation and biocatalysis and biotransformations. Topics range from complex reactions to the intricacies of catalyst preparation for supported nanoparticles, while chapters illustrate the challenges facing catalytic science and the directions in which the field is developing. Edited by leaders of the UK Hub, this book provides insight into one of the most important areas of modern chemistry - it represents a unique learning opportunity for students and professionals studying and working towards speeding-up, improving and increasing the rate of catalytic reactions in science and industry.