Synergistic Enhancement of Vectorial Separation of Photogenerated Charge Carriers via Heterojunction and Quantum Confinement Effects

Abstract

Solar-driven water splitting for hydrogen production is a promising solution to the energy crisis. Reducing the recombination of photogenerated charge carriers is a key strategy for enhancing the hydrogen evolution performance. In this study, a type-II heterojunction catalyst, CdS/Co₃O₄, was successfully prepared using a self-assembly method. The tight coupling between CdS and Co₃O₄ facilitates efficient electron transfer. The heterojunction promotes the separation of photogenerated electrons, thereby reducing the charge carrier recombination. Additionally, the quantum confinement effect of Co₃O₄ shortens the electron migration distance. Under illumination with a 10 W white light source, the hydrogen evolution rate of CdS/Co₃O₄ reached 21.07 mmol g^–1 h^–1, approximately three times that of pure CdS. Electron paramagnetic resonance and density functional theory calculations were employed to elucidate the electron transfer mechanism during the photocatalytic process. This study provides a theoretical foundation for the design and mechanistic investigation of quantum-dot-based heterojunction photocatalysts.