Mechanism of CO preferential oxidation catalyzed by Cu (n) Pt (n=3-12): a DFT study

摘要

The CO preferential oxidation reaction (PROX) is particularly well suited for hydrogen purification for proton exchange membrane fuel cell applications. In this work, the mechanism of CO-PROX catalyzed by Cu (n) Pt (n = 3-12) clusters has been studied by density functional theory calculations. The calculated results indicate that the most favored adsorption site of H-2 for all clusters is on the Pt sites, and O-2 prefers to bind on Cu sites and CO bind on Pt sites. The lowest energy barrier for hydrogen dissociation is 0.02 eV. Smaller H-Pt bond length of Cu (n) PtH2 corresponds to larger H-H bond length. CO-PROX occurs via the main intermediates of COOH and OH. Cu6Pt is proposed as the most effective catalyst for CO-PROX. To understand the high catalytic activity of Cu (n) Pt clusters, the nature of the interaction between adsorbate and substrate is also analyzed by detailed electronic local density of states. These findings enrich applications of Cu-based materials to the field of high-activity catalysts.