Coupled Regulation of Interfacial Hydrogen Spillover and Charge Transfer in Defective In ₂ O ₃ /ZnS for Enhanced Photocatalytic Hydrogen Evolution

Photocatalytic water splitting for hydrogen production is a pivotal technology for converting solar energy into chemical energy. Nevertheless, the hydrogen spillover effect in photocatalytic hydrogen evolution remains poorly understood, particularly given the potential interplay between charge transfer and proton transport. In this work, we employ an in situ topologically transformed heterostructure In2O3/ZnS as a model system to systematically investigate the coupled charge and proton dynamics. Derived from Zn-In LDHs (layered double hydroxides), the In2O3/ZnS composite offers advantages including a relatively high specific surface area and the favorable introduction of defects. Our experimental results demonstrate that intrinsic defects within the In2O3/ZnS composite not only act as defect energy levels to broaden light absorption but also directly participate in the photocatalytic hydrogen evolution reaction by modulating the hydrogen spillover process. Characterizations reveal that hydrogen spillover promotes proton transfer, while interfacial charge transfer accelerates charge migration. The synchronous spatial separation of charge carriers and protonic species, arising from the high-density boundaries in the in situ topologically converted heterostructure, synergistically enhances the photocatalytic hydrogen evolution performance. This dual-migration strategy for charges and protons provides insights for the rational design of efficient heterostructures for both photocatalytic and electrocatalytic applications.