Tuning the catalytic activity of Ag-Pd alloy cluster for hydrogen dissociation by controlling the Pd ratio

The global minima of the PdnAg(8-n) clusters are determined based on the particle swarm optimization algorithm, merging density functional theory calculations. It is found that the HOMO-LUMO gap of the PdnAg(8-n) clusters can be controlled from 0.06 to 0.91 eV by turning the Pd ratio. The activity of the optimized PdnAg(8-n) clusters towards H-2 adsorption and dissociation at low coverage are studied. We propose that the Pd5Ag3 is a proper candidate for H-2 dissociation with the lowest Pd usage. We also find that the Pd2Ag6 can serve as a promising candidate for H-2 storage, because it has the largest compositional stability and is the most efficient cluster for H-2 adsorption and disfavored for H-2 dissociation. (C) 2015 Elsevier B.V. All rights reserved.