II-VI semiconductor nanoplatelets for photocatalysis: From structure regulation to mechanistic understanding and applications

II-VI semiconductor nanoplatelets have emerged as promising photocatalysts due to their tunable band structures, low cost, and unique two-dimensional geometry. The atomically confined thickness induces strong quantum confinement, enabling efficient charge separation, abundant surface-active sites, and precise structural regulation. These features make them attractive for solar-driven processes, including hydrogen evolution, CO₂ reduction, and pollutant degradation. This review summarizes recent advances in the controlled synthesis and structural regulation of II-VI nanoplatelets, focusing on thickness control, ligand engineering, defect modulation, heterostructure design, and ion exchange-driven transformations. The photocatalytic mechanisms are discussed by correlating structural characteristics with light absorption, charge dynamics, and surface reaction pathways. Representative applications in energy conversion and environmental remediation are highlighted. Finally, current challenges and future perspectives are outlined to guide the rational design of high-performance nanoplatelet-based photocatalysts. This work provides a framework for the rational design of efficient and stable nanoplatelet-based photocatalysts.