Atmosphere-Dependent Strong Metal–Support Interactions in Au/ZnO Catalysts and Their Overlayer Permeability

The oxidative strong metal–support interaction (O-SMSI) emerges as a pioneering approach for promoting the formation of overlayers, which has garnered significant interest in the exploration of the synthesis of O-SMSI materials. However, the manipulation of the overlayer is rarely discussed and presents a challenge due to its trace presence on the nanoparticle (NP) surface, which impedes the development and utilization of the O-SMSI. In this work, we demonstrate a strong correlation between the treatment atmosphere and the state of the permeable overlayer in the Au/ZnO catalyst. The ZnO overlayer can be formed in both oxidative and inert atmospheres, but the permeability of the overlayer occurs under an oxidative atmosphere. The difference in the permeabilities of the overlayer, at similar particle sizes, leads to a reaction rate difference of approximately 1.4 times. While the permeability of the ZnO overlayer is improved by an oxidative atmosphere treatment, it is also accompanied by an increase in the geometric strain in the ZnO matrix. The permeable ZnO formation is related to the process of gold species insertion into the ZnO matrix, as indicated by density functional theory calculations. This study is the first to describe the role of O2 in manipulating the O-SMSI and suboxide overlayers, offering a potential method for surface engineering.