Organic-inorganic DVA-COF@TiO2 S-scheme heterojunction for highly selective photocatalytic reduction of CO2 to CO

Photocatalytic reduction of CO 2 to produce high-value-added hydrocarbon fuels is expected to solve the severe predicament of energy shortage and the environmental governance challenges. Here, in-situ growth strategy is applied to couple TiO 2 nanoparticles with spherical covalent organic framework (DVA-COF) to form a DVA-COF@TiO 2 S-scheme heterojunction photocatalyst for CO 2 reduction. The as-prepared DVA-COF@TiO 2 S-scheme photocatalyst exhibited the enhanced photocatalytic CO 2 reduction rate (12.46 μmol g –1 h –1 ) and CO selectivity (92.22%). The S-scheme charge transfer mechanism was investigated by in-situ irradiated X-ray photoelectron spectroscopy, electron paramagnetic resonance, density functional theory calculation, and femtosecond transient absorption spectroscopy. In-situ diffuse reflectance Fourier transform infrared spectroscopy and free energy calculations have unveiled the process of photocatalytic CO 2 reduction and the reasons of the improved CO product selectivity of the heterojunction photocatalysts. This study provides a critical theoretical reference for the development of the novel organic-inorganic S-scheme heterojunction photocatalysts with higher CO selectivity, which is expected to inject strong power into the practical application of sustainable artificial photosynthesis technology.