Accelerated Water Oxidation Kinetics Induced by Oxygen Vacancies in the BiVO/CN S-Scheme Heterojunction for Enhanced Photocatalytic CO Reduction.

The solar-driven photocatalytic reduction of CO into fuels using a CN-based photocatalyst has shown great application potential in addressing challenges related to energy and CO emission. However, this process suffers from severe charge recombination and sluggish HO oxidation kinetics, resulting in low efficiency. In this study, a 2D/2D S-scheme heterojunction by combining oxygen vacancy-rich BiVO nanoflakes with CN nanosheets (denoted as O-BVO/CN) was fabricated to mitigate the aforementioned issues, where BiVO serves as a water oxidation booster and CN serves as the CO reduction center. By leveraging the synergistic effects of a lamellar morphology and an S-scheme charge-transfer pathway, the O-BVO/CN heterojunction achieves efficient charge separation while maintaining maximized redox capabilities. Moreover, theoretical calculations demonstrated that the O on the surface of BiVO reverses the rate-limiting step in HO oxidation while reducing its energy barrier, thereby accelerating reaction kinetics. The optimized O-BVO/CN S-scheme heterojunction demonstrates remarkably improved photocatalytic evolution rates for CO (13.8 μmol g h) and CH (5.9 μmol g h), which are approximately 3.8 and 3.5 times higher than those of CN nanosheets under visible-light irradiation, respectively. This work highlights the design and fabrication of highly efficient heterostructure photocatalysts for CO photoreduction.