Formation of Pt3O4 particles on PtO2–CeO2 solid solution

Abstract

Pt supported on CeO2 has various applications as a catalyst. Because chemical states of Pt are hugely significant in offering improved catalytic performance, it is necessary to understand structures of Pt on CeO2 at high temperatures. In this study, PtO2 and PtO2–CeO2 powders were prepared by precipitation in molten sodium nitrate, and their thermal decomposition in air was examined by X-ray diffraction. When PtO2 powder is heated at 600 °C, the oxide decomposes into Pt phase which is accompanied by a slight Pt3O4 phase. On the other hand, in a heat treatment of a PtO2–CeO2 powder, the formation of Pt phase is hindered and Pt3O4 phase is formed preferentially. These results suggest that supporting Pt on CeO2 contributes not only to maintenance of fine dispersion at high temperatures, but also to formation of the Pt3O4 phase, which might play an important role in catalytic reactions. Observation with transmission electron microscopy and chemical analysis with X-ray photoelectron spectroscopy were performed on the powders before and after the heat treatment to discuss the formation of Pt3O4 particles on a PtO2–CeO2 solid solution.