Construction of Dual Active Sites in Perovskite Oxide for Targeted Photocatalytic CO2 Reduction to CH4

Photocatalytic CO2 methanation is considered a sustainable solution for the effective utilization of CO2. However, it remains a major challenge for the process to achieve high selectivity for a single product such as CH4 in view of the complexity of the multielectron transfer mechanism. Herein, a SrTiO3-based catalyst with adjacent Bi–Mn dual active sites is developed for photocatalytic CO2 reduction. In the structure of SrTiO3 codoped with Bi and Mn atoms, theoretical calculations and experimental studies show that the oxygen vacancy in the MnO6 octahedron induces Jahn–Teller distortion, which leads to a rearrangement of the Mn d-orbital electrons. The altered dz2 orbital energy level interacts electronically with the adjacent Bi atom p orbital, forming the electron-rich Bi–Mn dual active sites with improved surface electron transfer capability. Electronic coupling interactions within the Bi–Mn dual active sites can optimize the adsorption capabilities for reaction intermediates, thereby lowering the reaction energy barrier for the CH4 product pathway as well as reducing the energy barrier for surface refreshment. The results show that the Sr0.8Bi0.2Ti0.8Mn0.2O3 nanosheet achieves a high selectivity of 84.3% for the CH4 product with a yield of 30.6 μmol g–1 h–1 in pure water. This work provides novel insight into the design of dual active site catalysts for the selective reduction of CO2.