Boosting Photocatalytic CO Reduction via Oxygen Vacancy Defective S-Scheme InO@NiInS Hollow Spheres with Efficient Charge Separation.

One of the most promising approaches to carbon neutrality is photocatalytic conversion of CO into chemical fuels. Nevertheless, it continues to face significant challenges in addressing high charge-transfer resistance and sluggish charge-transfer kinetics, substantially limiting its practicality for large-scale deployment. Here, we prepared S-scheme InO@NiInS hollow spheres (HSs) utilizing an ordinal solvothermal coating of Ni-MOF and a high-temperature sulfidation process of the In(OH)-InOOH hollow sphere precursor, which facilitated close contact between the two components. This close contact provides an efficient channel for the smooth transfer of light-induced charges across the heterointerface. The S-scheme InO@NiInS heterojunction is crucial for boosting the separation of space charges, which promotes the efficiency of multiple photochemical processes. Meanwhile, the oxygen vacancy defects generated in InO provide more active sites and promote charge-transfer in the S-scheme heterojunction. The combined benefits of these advantages enable the enhanced S-scheme InO@NiInS HSs to demonstrate remarkable photocatalytic performance in CO reduction. In situ X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) provide evidence for the S-scheme charge transfer pathway. This research introduces a practical approach aimed at enhancing robust interactions among the various components of heterostructure catalysts, thereby facilitating charge transfer and improving the photocatalytic activity.