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

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