Hierarchical In2S3 microflowers decorated with WO3 quantum dots: Sculpting S-scheme heterostructure for enhanced photocatalytic H2 evolution and nitrobenzene hydrogenation

Solar energy conversion and high-value chemical production are of utmost importance. However, the development of efficient photocatalysts with strong redox ability remains challenging. Here we report a unique 3D/0D In2S3/WO3 S-scheme heterojunction photocatalyst obtained by depositing WO3 quantum dots (QDs) onto hierarchical In2S3 microflowers. The In2S3/WO3 composite exhibits outstanding visible light absorption, with a maximum optical response of up to 600 nm. The electronic interaction and charge separation at interfaces are explored by in situ X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations. The difference in work function causes In2S3 to donate electrons to WO3 upon combination, leading to the formation of an internal electric field (IEF) at the interfaces. Due to the IEF and bent energy bands, the transfer and separation of photogenerated charge carriers follow an S-scheme pathway within In2S3/WO3. Owing to the strong redox ability, spatial charge separation and lower H2-generation barrier of S active sites, the optimized In2S3/WO3 heterojunctions show enhanced photocatalytic hydrogen evolution of 0.39 mmol h–1 g–1, 6.7 times that of pristine In2S3. In addition, the In2S3/WO3 S-scheme heterojunctions afford a remarkable activity for photocatalytic nitrobenzene hydrogenation with nearly 98% conversion and 99% selectivity of aniline within 1 h. Our work might present new insights into developing efficient S-scheme heterojunctions for various photocatalytic applications.