2, East China University of Science and Technology, Shanghai, , China
Ceria supported Pt nanocatalysts have demonstrated superior catalytic properties for water gas shift reaction . By downsizing noble metal nanoparticles to small clusters or single atoms, the effective use of noble metals can be maximized and unique catalytic properties can be realized . In order to effectively increase the surface area of the ceria support and to explore the unique catalytic properties of small ceria clusters, we designed a hierarchical system that consists of Pt single atoms trapped onto small ceria clusters which are supported on ZnO nanowires. Our goal is to use the ceria nanoclusters to stabilize the Pt single atoms while simultaneously utilize the Pt-ceria interaction to tune the catalytic properties of the Pt1-CeO2-ZnO nanoscale architected catalytic system. In order to implement such a strategy, we used aberration-corrected environmental TEM to investigate the formation processes of the ceria clusters on the ZnO NWs. We further studied how the Pt single atoms or small clusters interact with the ceria nanoclusters under gas environment or at elevated temperatures. Dynamic observations of the movement of ceria clusters and the sintering behavior of the Pt single atoms will be discussed .
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 This work was funded by NSF under CHE-1465057. We acknowledge the use of facilities in the John M. Cowley Center for High Resolution Electron Microscopy at Arizona State University.