Engineering ZnS quantum dots for photocatalysis: Synthesis, modifications, and multifunctional applications

Photocatalysis is an advanced technology that efficiently converts solar energy into chemical energy, attracting widespread attention in environmental remediation, energy development, and biomedical applications. ZnS quantum dots (ZnS QDs), as a representative wide-bandgap semiconductor, exhibit unique quantum confinement effects, tunable optoelectronic properties, and a high specific surface area, making them a promising metal sulfide photocatalyst. This review systematically summarizes recent advances in ZnS QD-based photocatalytic systems, with a focus on material design strategies and multifunctional applications. First, the fundamental mechanisms of ZnS QDs in photocatalysis are introduced, followed by a discussion on their synthesis methods. Several strategies for enhancing the photocatalytic activity of ZnS QDs, including surface modification, elemental doping, heterojunction formation, and coupling with carbon or organic materials, are discussed in detail. Furthermore, we comprehensively review the applications of ZnS QDs in the photocatalytic degradation of pollutants, water splitting for H2 production, CO2 reduction, N2 fixation, antimicrobial activity, and organic synthesis, highlighting their breakthroughs in biomedical field, such as near-infrared-activated antimicrobial systems and tumor-specific photodynamic/photothermal therapy. Finally, by analyzing the current challenges of ZnS QDs in photocatalysis, we propose three future research directions to promote their practical applications in sustainable energy, environmental restoration, and precision medicine.