CO Oxidation on the Ag-Doped Au Nanoparticles

Abstract

The CO oxidation reactivity of negatively and positively charged isolated cuboctahedron (c-Oh) Au13 and Au12Ag nanoparticles is investigated using density functional theory calculations. Charging the nanoparticles modifies the structural stability of the Au13 and Au12Ag nanoparticles as well as the electron distribution in the core and shell atoms. An Ag-doping in gold (Au) clusters improves CO or O2 adsorption on Au12Ag cluster. For Au13 cluster, CO preadsorption increases the capacity of CO and O2 coadsorption, but the result is opposite for Au12Ag cluster. The neutral Au13 and Au12Ag clusters exhibit relatively poor reactivity for CO oxidation, while the reactivity is enhanced significantly by excess electrons. In comparisons of the results of CO oxidation on Ag- and un-doped Au nanoparticles, we discover Ag-doping in Au cluster surely decreases first energy barrier (Ea), and increases slightly second energy barrier (Eb). This work provides a fundamental insight into how the excess charges affect the adsorption activity and how the Ag-doping in Au clusters adjusts the catalytic activity for Ag- or un-doped c-Oh Au clusters. Reaction pathways for CO + O2 → CO2 + O associated with Au13 and Au12Ag clusters. Here, * denotes the adsorbed species on an Au13 or Au12Ag cluster. The reactivity of CO oxidation on Au nanoparticles is enhanced significantly by excess electrons. An Ag-doping in Au cluster improves CO or O2 adsorption on Au12Ag cluster. Ag-doping in Au clusters decreases first energy barrier (Ea), and increases slightly second energy barrier (Eb). Ag-doping in Au nanoparticles weakens C–Au bond at CO + O2 coadsorption state, and strengths CO–O bonds at transition states and intermediate state.