Theoretical Investigations of Pt1@CeO2 Single-Atom Catalyst for CO Oxidation

In the present study, we perform systematic density functional investigations on the single-atom Pt catalysts dispersed on CeO2 (111), (110), and (100) surfaces. The structural and electronic properties of these SACs and their corresponding catalytic activity for CO oxidation are discussed. It is shown that the single-atom Pt substitution of a lattice Ce ion is thermodynamically stable on each ceria surface. On the (111) and (100) surfaces, the single Pt atom is found to exist at an oxidation state of +4 upon replacement of Ce4+, while, on the (110) surface, it exhibits a planar structure with a reduced oxidation state of +2 due to the spontaneous formation of surface peroxide O(2)(2-)species. On all of the surfaces, CO oxidation is found to follow the Mars-van Krevelen mechanism. It is the single-atom Pt, rather than the lattice Ce, that acts as the electron acceptor/donor in the redox processes during the whole catalytic cycle. This work provides insights on the significant role of a single metal atom on reducible oxide of ceria and others.