Boosting photocatalytic hydrogen evolution on hollow Cu_2−xSe@ZnIn₂S₄ core–shell nanocubes via synergically utilizing p–n heterojunction and near-infrared plasmonic effect

Nowadays, photocatalytic water splitting for hydrogen production is widely recognized as a promising solution to solve both energy shortages and environmental pollution. Nevertheless, photocatalytic hydrogen evolution is currently hindered by challenges, such as inefficient photogenerated carrier separation and migration and inadequate light absorption by photocatalysts. To overcome such challenges, we herein engineered hollow Cu_2−xSe@ZnIn₂S₄ core–shell heterostructures (HCSHs) via synergistic utilization of energy level engineering, interfacial engineering, and local surface plasmon resonance (LSPR) effect. The optimal sample exhibits an outstanding hydrogen evolution rate (46.78 mmol·g⁻¹·h⁻¹) under visible–near-infrared (VIS–NIR) irradiation, which is 1.78 times that under VIS irradiation alone and 7.8 times that of ZnIn₂S₄ reference under the same illumination condition. Comprehensive studies demonstrate that the built-in electric field within the p–n heterojunctions, along with the unique core–shell structure, significantly enhances the separation and directional migration of photogenerated carriers. Meanwhile, the NIR LSPR effect from the Cu_2−xSe component lowers the apparent activation energy and accelerates the reaction kinetics mainly via plasmonic hot electron-assisted cleavage of the adsorbed water, with photothermal heating providing a secondary contribution. This work is of great importance in developing highly efficient photocatalysts and in boosting LSPR-enhanced photocatalytic applications.