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Design of thin-film nanocatalysts for on-chip fuel cell technology

Article UBCN - Nanoscale 6

A DFT study of oxygen dissociation on platinum based nanoparticles

A4-NeymanK-FigAbstract.gif

Nanoscale 6, 1153 (2013) - read more on RCS pages

Paul Jennings1, Hristiyan A. Aleksandrov2,3, Konstantin M. Neyman2,4, and Roy L. Johnston*,5

1School of Chemical Engineering, University of Birmingham, Edgbaston, UK
2Departament de Química Física & IQTCUB, Universitat de Barcelona, Spain


3Faculty of Chemistry and Pharmacy, University of Sofia, Sofia, Bulgaria
4Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
5School of Chemistry, University of Birmingham, Edgbaston, UK

Density functional theory calculations are performed on 38 and 79 metal atom truncated octahedron clusters to study oxygen dissociation as a model for the initial stage of the oxygen reduction reaction. Pure platinum and alloyed platinum–titanium core–shell systems are investigated. It is found that barrierless oxygen dissociation occurs on the (111) facet of the pure platinum clusters. A barrier of [similar]0.3 eV is observed on the (100) facet. For the alloyed cluster, dissociation barriers are found on both facets, typically [similar]0.6 eV. The differences between the two systems are attributed to the ability of oxygen to distort the (111) surface of the pure platinum clusters. We show that flexibility of the platinum shell is crucial in promotion of fast oxygen dissociation. However, the titanium core stabilises the platinum shell upon alloying, resulting in a less easily distortable surface. Therefore, whilst an alloyed platinum-titanium electrocatalyst has certain advantages over the pure platinum electrocatalyst, we suggest alloying with a more weakly interacting metal will be beneficial for facilitating oxygen dissociation.