Dr David Willock

Dr David Willock

Reader in Theoretical and Computational Chemistry

School of Chemistry

Email:
willockdj@cardiff.ac.uk
Telephone:
+44 (0)29 2087 4779
Fax:
+44 (0)29 2087 4030

David Willock's research group is concerned with the use of computer simulation to understand materials with a particular focus on catalysis and related areas.

Heterogeneous catalysis depends on the adsorption and reaction of molecules at a surface. The main materials of interest are metals, oxides, microporous structures and supported metal nanoparticles with calculations aimed at understanding the properties of these systems and the reactions that are catalysed on their surfaces.

Simulation of structure and properties at the molecular level is carried out using a combination of quantum chemical and atomic forcefield methodology. The development of Monte Carlo simulation for host/guest systems has allowed us to explore templating and shape selectivity in zeolites and to generate new models of the pore structure of polymer materials. Periodic DFT has been applied to the adsorption and isomerisation of ketones on Pt surfaces and the reactions of molecules at defects on oxides.

In most cases collaboration with colleagues in spectroscopy, surface science and catalysis has been used to gain insight into the accuracy of the modelling protocols and provide a more rounded description of the "real world" system.

Links

Personal Web Sites: CCI, http://novacam.eu/

PhD, Queen Mary and Westfield College, London., Dept. Physics, (1991, E.G. Wilson), PDRAs UCL (S.L.Price), Royal Institution (C.R.A.Catlow), Daresbury Labs. (M.Leslie), Leverhulme Centre, Liverpool (G.J.Hutchings). Appointed Lecturer in Cardiff (1998) promoted to Senior Lecturer (2003).

Member of RSC (CChem), IOP (CPhys), SCI, ACS.

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1998

CH3204 Symmetry, Spectroscopy and Quantum Mechanics

CH3304 Advanced Physical Chemistry

CH3406 Theoretical Methods

CHT109 Applications of Computational Chemistry to Materials Science

CHT232 Key skills for Postgraduate Chemists

CHT401 Advanced Heterogeneous Catalysis

Details of each module is available in course finder

Our interest in periodic DFT calculations for surfaces important in catalysis is exemplified by the images below on MoO3. This important oxidation catalyst is known to form as a defective (sub-stoichiometric) material with surface oxygen defects. Some oxidation processes also involve the use of lattice oxygen following the Mars-van Krevelen mechanism. The exchange of oxygen with the surface then becomes key to understand the oxygen supply.

Formally, the removal of oxygen from the MoO3 surface shown below involves a reduction of a single Mo centre from Mo6+ to Mo4+. GGA-DFT fails to reproduce this effect since the electrons left behind after O is removed delocalise through the conduction band of the material. We have used the Hubbard U parameter extension of DFT to consider this system, which increases the band gap (closer to the experimental) and gives localised states at the Mo centre. The spin density shows a triplet ground state for this defect.

Molecular oxygen will adsorb at this defect site, donate an electron to the Mo centre and produce a surface superoxo (O2-) species. The superoxo itself may play a role in oxidation catalysis, or go on to heal the defect.