Deciphering the Metal-Support Interaction of Au/ZnO Catalyst Induced by H₂ and O₂ Pretreatment

Metal-support interaction (MSI) provides great possibilities to tune the activity, selectivity, and stability of heterogeneous catalysts. Herein, the Au/ZnO catalyst is prepared by commercial ZnO and chloroauric acid, and the structure evolution of the catalyst pretreated by H-2 and O-2 gas at varied temperature is investigated to provide mechanistic insights of MSI. It is found that the H-2 treatment at 300 degrees C and above can induce the formation of both the ZnOx overlayer and bulk Au-Zn alloy. In contrast, the O-2 treatment can form the ZnOx overlayer at 500 degrees C and above without the formation of Au-Zn alloy. It is also revealed that the ZnOx overlayer is dynamically stable (permeable), which can provide access for reactant molecules during the reaction process. And, the Au-Zn alloy can recover to Au and ZnO under the CO oxidation reaction condition, which can be deemed as a re-activation process that endows H-2-treated samples with the superior activity and stability.