Recent Progress and Engineering Strategies in Zn _<i>x</i> Cd _{1– <i>x</i>} S-Based Photocatalysts for Solar-Driven Hydrogen Generation: Opportunities and Challenges

Zinc cadmium sulfide (ZnxCd1–xS)-based materials have emerged as promising photocatalysts for solar-driven hydrogen production due to their tunable band gap and strong visible-light absorption. The photocatalytic performance of ZnCdS is strongly influenced by its morphology, crystal structure, and synthesis methods, which govern light harvesting, charge transport, and surface reaction kinetics. However, the practical application of ZnCdS is limited by photocorrosion, rapid charge-carrier recombination, and insufficient long-term stability. In this context, this Review systematically summarizes recent progress in ZnCdS-based composites, with particular emphasis on morphology control, synthesis strategies, and compositional regulation. Various material design and engineering strategies, including heterojunction construction, cocatalyst loading, doping, and defect creation, are discussed in relation to their roles in addressing the above-mentioned limitations, enhancing charge separation, and hydrogen evolution efficiency. In addition, recent advances in elucidating photocatalytic mechanisms are also discussed, particularly through in situ characterization and theoretical calculations, providing deeper insights into charge-transfer pathways and reaction intermediates. Finally, the current challenges and future research directions for designing efficient and durable ZnCdS-based photocatalysts are outlined.