Coupling Photothermal Effect in N-Doped Hollow Carbon Spheres with ZnIn2S4 Boosts Solar Hydrogen Evolution

To address the challenges of low solar energy utilization efficiency and rapid recombination of photogenerated charge carriers in photocatalytic hydrogen evolution, this study successfully constructed a composite photocatalyst of ZnIn2S4 (ZIS) supported on N-doped hollow carbon spheres (N-HCS), denoted as ZIS/N-HCS, via a combination of template etching and in situ growth strategies. Characterization results demonstrate that this hollow structure possesses a high specific surface area (48.41 m2/g) and a narrowed bandgap (2.41 eV), achieve broad-spectrum light absorption, thereby enabling the catalyst to generate a local hot spot temperature of 136 °C under AM1.5G conditions. The optimized ZIS/N-HCS-0.30 sample exhibited a significantly enhanced photocurrent response (8.26 μA cm−2) and improved charge separation efficiency. When evaluated at a set solution temperature of 20 °C, the material exhibited a photocatalytic hydrogen evolution rate of 17.03 mmol g−1·h−1, which is 7.06 times higher than that of pure ZIS. Furthermore, it demonstrated excellent cycling stability. This work elucidates the synergistic role of the hollow photothermal structure in enhancing solar energy utilization and catalytic reaction kinetics, providing a new strategy for designing efficient solar-driven hydrogen production systems.