Application of density functional theory to CO tolerance in fuel cells: a brief review.

The large scale practical application of fuel cells in the hydrogen economy is possible only with a dramatic reduction of the cost and significant improvement of the electrocatalytic properties of the electrodes. This can be achieved through rational design of new materials, which requires an understanding of the microscopic mechanisms underlying electrocatalysis. We review briefly some applications of density functional theory (DFT) to this problem, with particular reference to the observed high CO tolerance of Pt-Ru-based anodes. These DFT-based calculations trace the changes in the surface electronic structure and the energy landscape induced by formation of Pt islets on facets of Ru nanoparticles which lead to the preferred diffusion of CO from Pt sites to Ru, where it exhibits a high rate of reaction with hydroxyls, which are generally present. We also consider the energetics of stabilization of the Pt islets on the Ru nanoparticles.