Dynamic oxygen vacancies inducing dipole-limited domain field to propel electron transfer in S-scheme heterojunctions for high-efficiency photothermal CO2 reduction

The photothermal catalytic reduction of CO 2 to synthesize high-value hydrocarbon fuels has attracted significant attention. However, current conversion efficiency remains constrained by the dual limitations of insufficient photogenerated carrier concentration and the difficulty in effectively adsorbing and activating CO 2 . This work first successfully synthesized g-C 3 N 4 nanohollow spheres using a hard template method and ultrathin Bi 2 MoO 6 nanosheets via a solvothermal method, and then fabricated an S-scheme heterojunction by electrostatic assembly. Crucially, during the photothermal catalytic reaction, the dynamic formation of photogenerated oxygen vacancies and their induced dipole-limited domain field (DLDF) structure were identified as the key mechanism driving the exceptionally high activity in CO 2 photoreduction. In situ electron paramagnetic resonance spectroscopy directly demonstrated the dynamic cycling of the photogenerated oxygen vacancies during the catalytic reaction. Density functional theory calculations and carrier dynamics characterization analysis confirmed the synergistic effect of the DLDF in optimizing carrier kinetics and enhancing CO 2 adsorption. Ultimately, a high CO production rate of 48.69 μmol·g −1 ·h −1 was achieved. This work integrates heterojunction construction and morphology control strategies to achieve synergistic enhancement of photothermal catalytic performance and elucidates the intrinsic mechanism for the activity improvement. It provides an effective way for developing efficient heterojunctions for photothermal catalytic CO 2 reduction.