The First-Principles Study on the Mechanism of the RWGS Reaction Catalyzed by Pt1@CeO2-x(110) Single-Atom Catalyst

Abstract

CeO₂ exhibits superior catalytic activity and selectivity in the reverse water–gas shift (RWGS) reaction when combined with transition metals. Herein, a density functional theory (DFT) study was conducted to systematically investigate the mechanism of the RWGS reaction catalyzed by a Pt₁/CeO_2-x(110) single-atom catalyst. The dominant pathways for the H₂ dissociation and the oxygen vacancy (VO) formation on Pt₁/CeO₂(110) surfaces, as well as for the H₂ dissociation on Pt₁/CeO2-x(110) surfaces, were elucidated. The RWGS reaction pathways involving linear and bent CO₂ adsorption on the Pt₁/CeO_2-x(110) surface were explored, including the conventional redox mechanism, formate (HCOO) pathway, and carboxyl (COOH) pathway. The COOH pathway for linearly adsorbed CO₂ (li-CO₂*→COOH*→CO*+OH*→CO*+H₂O*) was found to be the most favorable route for CO production. The rate-determining step of the overall reaction is the dissociation of COOH* (COOH*→CO*+OH*), which has a relatively low activation barrier of 0.65 eV. These findings not only provide valuable theoretical insights into the catalytic performance of CeO₂-based materials in the RWGS reaction but also enhance the understanding of its reaction mechanisms.