Promoting CO 2 -to-CO Photoconversion by Regulating Electron Transfer in Heterojunctions

In the present study, efficient photocatalytic reduction of CO2 to low-carbon hydrocarbons (CO and CH4) was achieved via the construction of a Bi2O3/Mn3O4 heterojunction composite photocatalyst. This catalyst exhibits outstanding catalytic performance under pure aqueous phase and sacrificial-agent-free conditions, achieving a CO yield of 10.164 μmol·g-1·h-1 with a CO selectivity of 76.04%. Notably, the total selectivity for C1 products (containing only CH4 and CO, with no other carbonaceous products detected) achieves 94.3%. The characterization results show that the heterojunction structure effectively promotes the separation and transport of photogenerated carriers, while the bimetallic synergistic effect enhances the intrinsic activity of the active site. In situ infrared spectroscopy reveals that intermediate *COOH plays a critical role in conversion of CO2 to CO. The emergence of peaks corresponding to intermediates such as *CHO and *CH3O indicates the effectiveness of the catalyst in driving the conversion of CO2 toward C1 products. A more intense *COOH peak in the Fourier transform infrared spectroscopy (FT-IR) of Bi2O3/Mn3O4-2 further demonstrates its superior capability to convert more CO2 into CO. This study proposes a strategy to enhance photocatalytic activity by modulating the electron transfer capability of the material.