Modulating the coordination environment in CeO2-x towards enhanced photocatalytic CO2 conversion stability and performance

Oxygen vacancy (Vo) engineering has been recognized as one of the most effective strategies for enhancing the photocatalytic CO 2 conversion performance of metal oxides, as it can simultaneously facilitate photogenerated charge carrier separation efficiency and provide additional surface reaction sites. However, the wide application of Vo engineering in photocatalysis are limited by its poor stability, owing to the easy recovery of these vacancy defects by atmospheric oxygen. Herein, we develop an indium (In) doping strategy to regulate the coordination environment in CeO 2 with abundant Vo (CeO 2- x ), thereby enhance its stability during photocatalytic CO 2 conversion. Confirmed by positron annihilation lifetime spectroscopy (PALS), In dopants combine with Vo by substituting for part of Ce 4+ , forming In 3+ –Vo complexes that effectively inhibit the formation of unstable vacancy clusters. Such In 3+ –Vo complexes can also reduce the energy required for formation of the CO products. Therefore, the optimized In-doped CeO 2- x exhibits excellent photocatalytic CO 2 conversion performance, with a CO yield of 301.6 μmol·g −1 after 5 h of light irradiation, and maintain high activity after four cycles of experiments. Comprehensive experimental and theoretical studies indicate that the introduction of In doping not only significantly improves the stability of Vo in CeO 2- x , but also reconstruct the reaction kinetics of the CO 2 conversion by forming In 3+ –Vo complexes thus facilitating the overall reaction. An indium doping strategy is employed to stabilize the oxygen vacancies on the CeO 2- x by forming In 3+ −Vo complexes, which cannot only inhibit the formation of unstable vacancy clusters but also lower the energy for the formation of the CO products towards enhancing photocatalytic performance and stability.