Enhanced Solar Fuel Production over In 2 O 3 @Co 2 VO 4 Hierarchical Nanofibers with S-Scheme Charge Separation Mechanism.

The conversion of CO 2 into valuable solar fuels via photocatalysis is a promising strategy for addressing energy shortages and environmental crises. Here, novel In 2 O 3 @Co 2 VO 4 hierarchical heterostructures are fabricated by in situ growing Co 2 VO 4 nanorods onto In 2 O 3 nanofibers. First-principle calculations and X-ray photoelectron spectroscopy (XPS) measurements reveal the electron transfer between In 2 O 3 and Co 2 VO 4 driven by the difference in work functions, thus creating an interfacial electric field and bending the bands at the interfaces. In this case, the photogenerated electrons in In 2 O 3 transport to Co 2 VO 4 and recombine with its holes, indicating the formation of In 2 O 3 @Co 2 VO 4 S-scheme heterojunctions and resulting in effective separation of charge carriers, as confirmed by in situ irradiation XPS. The unique S-scheme mechanism, along with the enhanced optical absorption and the lower Gibbs free energy change for the production of * CHO, significantly contributes to the efficient CO 2 photoreduction into CO and CH 4 in the absence of any molecule cocatalyst or scavenger. Density functional theory simulation and in situ diffuse reflectance infrared Fourier transform spectroscopy are employed to elucidate the reaction mechanism in detail.