Accelerating Electron Extraction Enabled by Colloidal Cu−Ga−Zn−S/Ni ₉ S ₈ Schottky Heterojunctions for Enhanced Solar Hydrogen Generation

Abstract Multinary copper‐based chalcogenide nanocrystals (MCCS NCs) have emerged as appealing photocatalysts for solar‐to‐hydrogen conversion due to their strong visible‐light absorption, low toxicity, and tunable composition, morphology and band structure. Nevertheless, for the individual MCCS NCs, the strong Coulomb attraction between photogenerated electrons and holes, as well as the transpositional defects introduced by the cation exchange process, severely impedes efficient charge separation and leads to severe electron annihilation and diminished photocatalytic activities. Herein, colloidal Ni 9 S 8 NCs synthesized via a one‐pot method are systematically screened and integrated with Cu−Ga−Zn−S (CGZS) NCs to construct CGZS/Ni 9 S 8 Schottky heterojunctions featuring strong electron‐coupling interaction. Under visible light, the optimized CGZS/2.0%Ni 9 S 8 demonstrated the highest photocatalytic hydrogen evolution activity of 6.68 mmol g −1 h −1 , representing a 3.6‐fold enhancement relative to the pristine CGZS NCs. Experiments and theoretical calculations reveal that the significantly enhanced photocatalytic performance originates from the construction of CGZS/Ni 9 S 8 Schottky heterojunctions, which promote the separation and migration of photogenerated electrons and holes. Meanwhile, the Ni 9 S 8 accelerates the electron extraction from CGZS NCs and serves as an efficient active site for enhanced solar hydrogen production reaction. This work offers a valuable strategy for constructing efficient photocatalytic systems based on colloidal heterojunctions of multinary Cu‐based chalcogenide nanocrystals.