In Situ Construction of S‐Scheme V In ‐Zn 2 In 2 S 5 /O‐Zn 2 In 2 S 5 p–n Homojunctions for Enhanced Photocatalytic Hydrogen Evolution

ABSTRACT The construction of p–n homojunctions represents a promising strategy for effective solar‐driven photocatalytic hydrogen evolution, owing to their inherent advantages of superior lattice matching and minimized charge transfer resistance. However, this approach remains largely unexplored. Herein, an interfacial p–n homojunction based on Zn 2 In 2 S 5 was fabricated through the controlled assembly of p‐type indium‐defected Zn 2 In 2 S 5 (V In ‐ZIS) nanoflowers onto n‐type oxygen‐doped Zn 2 In 2 S 5 (O‐ZIS) nanosheets. Integrated theoretical simulations and comprehensive characterizations demonstrate that the V In ‐ZIS/O‐ZIS homojunctions adopt an S‐scheme charge transfer route with a significantly strengthened interfacial electric field (IEF) effect, enabling spatial charge separation and a high driving force for both reduction and oxidation reactions. Consequently, V In ‐ZIS/O‐ZIS photocatalyst achieves a remarkable H 2 evolution rate of 17.03 mmol g −1 h −1 without any cocatalysts, which is 7.6‐ and 3.8‐fold higher than those of O‐ZIS (2.23 mmol g −1 h −1 ) and V In ‐ZIS (4.47 mmol g −1 h −1 ), respectively. Furthermore, an apparent quantum efficiency of 37.75% was attained at 370 nm. This work unravels the interplay among defect engineering, p–n homojunctions, and S‐scheme charge transfer. The findings provide a blueprint for designing advanced photocatalysts.