States of Pt/CeO2 catalysts for CO oxidation below room temperature

CO molecules can be efficiently oxidized over Pt/CeO2 catalysts, but the stability and reactivity of different states of Pt in the catalysts are still unclear. Here we combine experimental and computational methods to characterize Pt/CeO2 catalysts subjected to reductive and oxidative pre-treatments and exposed to CO oxidation reaction conditions. Particles of metallic Pt, known to be catalytically active at elevated temperature, are shown to be precursors for the formation, under operando conditions, of more stable PtOx particles that enable CO oxidation below room temperature. These PtOx particles are similarly stable to – but more active than – atomically dispersed Pt2+ species. The results and approaches presented in this study illustrate the complex response of catalytic materials to reaction conditions and pave the way for future efforts to improve Pt/CeO2 and similar catalysts using dedicated pre-treatment strategies.