Effect of Local Coordination Environments of Ceria Supported Pt Single Atom Catalyst on Oxidation Reactions

Ceria supported Pt single atom catalysts (SAC) (Pt₁/CeO₂) have been proposed as effective catalysts for several reactions. Controlling coordination environments of SAC can be a promising strategy to achieve satisfactory catalytic performance. Our joint experimental and computational study shows that the coordination environments of Pt₁/CeO₂ can be designed quite precisely via a simple calcination temperature-control strategy. Pt₁/CeO₂ prepared at 550 ^oC are found to mainly substitute Ce atoms at the edge sites (Pt/CeO₂-550) and are to be favored for CO oxidation reaction while those prepared at 800 ^oC mainly substitute Ce atoms on the terrace of CeO₂ (Pt/CeO₂-800) and are more effective for NH₃ oxidation. First principles calculations reveal that CO oxidation on Pt/CeO₂-550 does not require the consumption of surface O atoms while that on Pt/CeO₂-800 does. Similarly, NH₃ oxidation requires the consumption of surface O in both systems but the removal of surface O in Pt/CeO₂-550 requires higher energy than that in Pt/CeO₂-800. We will present an analysis of the geometric and electronic structure of the two types of Pt SAC that elucidate the origin of their contrasting reactivity.