Water-gas shift reaction catalyzed by Au32M6 (M = Cu, Pt, Pd, Rh, Ir) core-shell nanoclusters: A density functional theory study

Abstract

In this paper, the mechanism of water-gas shift reaction (WGSR) on Au32M6 (M = Cu, Pt, Pd, Rh, Ir) core-shell nanoclusters was investigated by density functional theory (DFT). The result shows that the unique synergistic effect in the core-shell structure of Au32M6 has a significant effect on the activity of the catalyst. Compared with the Au38 nanocluster, in the case of Au32M6, the charge transfer between the M6 core and the Au32 shell is larger after the formation of the core-shell nanocluster. The calculation of the binding energy indicates that the Au32M6 core-shell nanoclusters is more stable than Au38 nanocluster. The parameters for the center of d-band show that d-orbital electrons of Au32Pd6 nanoclusters closer to the Fermi level than other nanoclusters, which indicates the Au32Pd6 nanocluster have better electron activity. In addition, we also found out the minimum energy pathways (MEP) of each nanocluster based on the adsorption investigation of various species on Au32M6 in the WGSR. The calculation results show that Au32Pd6 nanocluster exhibits excellent catalytic activity for WGSR, the reaction pathway was ER 1 → ER 4 → ER 5-b → ER 6.