Cobalt doping-induced spin polarization and in-situ Bi⁰ decoration of Bi₂MoO₆ synergistically boosting photocatalytic CO₂-to-CO conversion

Photocatalytic CO₂ reduction utilizing solar energy to convert CO₂ into value-added fuels and chemicals is regarded as a promising strategy for alleviating energy crises and achieving carbon cycling. However, this process remains limited by rapid recombination of photogenerated carriers and sluggish CO₂ activation kinetics. In this work, Bi₂MoO₆ (BMO)-based photocatalysts with Co doping and in-situ formation of Bi⁰ nanocrystals were developed through a facile one-step solvothermal method. X-ray absorption spectroscopy analysis reveals that Co species are atomically dispersed within the BMO lattice in a CoO₄ coordination configuration. The weak crystal-field environment of CoO₄ preserves unpaired 3d electrons and induces spin-polarized electronic states, thereby decreasing the photocarrier recombination. Meanwhile, the Co doping leads to in-situ formation of Bi⁰ nanocystals on the catalyst surface, which promotes photocarrier transfer between Bi⁰ and Co-BMO and facilitates the photocarrier separation. The Co doping increases the CO₂ adsorption energy on the Bi active sites and decreases the energy barrier for the formation of the key *COOH intermediate. Moreover, the Co doping generates extra Co and Bi⁰ active sites for CO₂ photoreduction reactions. The cascade synergistic mechanism significantly boosts the photocatalytic CO₂-to-CO conversion, where the optimal Co₂-BMO sample delivers a CO production rate of 158.47 μmol g⁻¹ h⁻¹ that is 3.8 times higher than that of pristine BMO. This work provides an intriguing strategy for designing efficient solar-driven CO₂ conversion photocatalysts from the perspectives of electronic spin manipulation and interfacial charge transfer.