Study of O2 and OH adsorption energies on Pd-Cu alloys surface with a quantum chemistry approach

Variation of the intrinsic metal surface properties (lattice parameter, binding energy, work function (W-f), d-band filling and d-band center epsilon(d)) and O-2 and OH adsorption energies of on (1 1 1) Pd-Cu surface alloys were determined using ab initio program. Calculations of these parameters were based on plane waves approach on slab system with density functional theory (DFT) using the Vienna ab initio simulation program (VASP). It was shown that insertion of Cu atoms in Pd lattice affects geometric and electronic properties of Pd. These changes influence significantly O-2 and CH adsorption. Indeed, the highest OH adsorption energy and the lowest O-2 adsorption energy were found with 30 at.% in Cu. The volcano shape of the O-2 and CH adsorption with composition in Cu was explained, respectively, by firstly the highest bond distance that reduces adsorption energy of oxygen and the compromise between low DOS(E-f) and secondly, low band width (M reach for Pd3Cu which leads to the highest OH adsorption energy. O-2 and OH adsorption energies tendency could explain effect of the transition metal (TM) on kinetic current of the oxygen reduction reaction. (C) 2008 Elsevier Ltd. All rights reserved.