Boosting Photocatalytic CO2 Reduction via Oxygen Vacancy Defective S-Scheme In2O3@NiIn2S4 Hollow Spheres with Efficient Charge Separation

One of the most promising approaches to carbon neutrality is photocatalytic conversion of CO 2 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 In 2 O 3 @NiIn 2 S 4 hollow spheres (HSs) utilizing an ordinal solvothermal coating of Ni-MOF and a high-temperature sulfidation process of the In(OH) 3 -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 In 2 O 3 @NiIn 2 S 4 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 In 2 O 3 provide more active sites and promote charge-transfer in the S-scheme heterojunction. The combined benefits of these advantages enable the enhanced S-scheme In 2 O 3 @NiIn 2 S 4 HSs to demonstrate remarkable photocatalytic performance in CO 2 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.