Surface Functionalization and Defect Construction of SnO₂ with Amine Group for Enhanced Visible-Light-Driven Photocatalytic CO₂ Reduction

Photocatalytic CO2 reduction to hydrocarbon fuels through solar energy provides a feasible channel for reducing CO2 emission and resource depletion. Nevertheless, severe charge recombination and high energy barrier limit the CO2 reduction efficiency. Herein, a surface amine-functionalized SnO2 with oxygen vacancies (A-Vo-SnO2) is fabricated to achieve visible-light-driven photocatalytic CO2 reduction. Specifically, amino groups modified onto the surface of the catalyst can provide more active sites to promote the adsorption of CO2. Meanwhile, the synchronously induced oxygen defect level reduces the band-gap energy and expands the light-absorption region from UV light to visible light. The oxygen vacancies can modulate the electronic structure and work as the separation centers of spatial charges, thus promoting the interfacial charge transfer efficiency and providing more catalytic sites, as evidenced by experimental observation and theoretical calculation. As expected, this A-Vo-SnO2 exhibits a CH4 evolution rate of 17.27 mu mol g(-1) h(-1) without adding sacrificial agent and co-catalyst, much higher than 5.98 mu mol g(-1) h(-1) of pure SnO2. This work can provide significant inspiration for the design of defect engineering based on visible-light-driven photocatalysts towards photocatalytic CO2 conversion.