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 H₂ and O₂ gas at varied temperature is investigated to provide mechanistic insights of MSI. It is found that the H₂ treatment at 300 °C and above can induce the formation of both the ZnO_x overlayer and bulk Au-Zn alloy. In contrast, the O₂ treatment can form the ZnO_x overlayer at 500 °C and above without the formation of Au-Zn alloy. It is also revealed that the ZnO_x 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 H₂ -treated samples with the superior activity and stability.