Insights of the mechanisms for CO oxidation by N2O over M@Cu12 (M = Cu, Pt, Ru, Pd, Rh) core-shell clusters

Abstract

Catalytic conversion of N2O and CO to the nonharmful gases can relieve many environmental problems caused by them. A density functional theory study is performed to investigate the CO oxidation by N2O over the M@Cu12 (M = Cu, Pt, Ru, Pd, Rh) core-shell clusters. The stability of clusters and the adsorption of N2O are enhanced with the doping of noble metals which act as the electron collectors according to the NBO analysis. Two mechanisms (the stepwise adsorption mechanism and the co-adsorption mechanism) with adsorption of N2O on metallic clusters by N end and O end are well-established. On these clusters, the highest activation energy for the N2O decomposition to yield N2 is predicted to be 7.7 kcal/mol. The average barrier for the subsequent CO oxidation is about 14 kcal/mol, which is the rate-limiting step for the overall reaction. Overall, this oxidation process is both thermodynamically and kinetically favorable on Cu-based core-shell clusters. By comparison, the alloy clusters exhibit superior catalytic activities compared to pure Cu cluster for the rate-limiting step.