Enhanced Solar Fuel Production over In₂O₃@Co₂VO₄ Hierarchical Nanofibers with S-Scheme Charge Separation Mechanism

The conversion of CO₂ into valuable solar fuels via photocatalysis is a promising strategy for addressing energy shortages and environmental crises. Here, novel In₂O₃@Co₂VO₄ hierarchical heterostructures are fabricated by in situ growing Co₂VO₄ nanorods onto In₂O₃ nanofibers. First-principle calculations and X-ray photoelectron spectroscopy (XPS) measurements reveal the electron transfer between In₂O₃ and Co₂VO₄ 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 In₂O₃ transport to Co₂VO₄ and recombine with its holes, indicating the formation of In₂O₃@Co₂VO₄ 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 CO₂ photoreduction into CO and CH₄ 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.