Emerging Photocatalytic Applications of Transition Metal Dichalcogenides and Hybrid Composites for Energy Applications and Environmental Remediation

This review provides a critical evaluation of the photocatalytic processes that control the efficiency of transition metal dichalcogenides (TMDCs) and their hybrid composites in notable applications, including pollutant abatement, hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and carbon dioxide (CO₂) reduction. TMDCs possess excellent physicochemical characteristics with tuneable bandgaps, large surface area, and intense visible-light absorption that render them exceptionally competent for initiating photo-induced redox reactions. The review highlights mechanistic understanding concerning charge carrier generation and separation, defect engineering, and interfacial electron transfer, all of which is a key to improved photocatalytic performance. Particular focus is on pollutant degradation mechanisms, water splitting kinetics, and CO₂ photoreduction mechanisms. Though promising, TMDCs face challenges such as photo-corrosion, short-term stability issues, and scale-up limitations. To overcome these challenges, the formation of heterojunctions with visible-light-active semiconductors, such as halide perovskites, is emphasized as a potential method to enhance charge separation and broaden spectral response. Furthermore, the integration of TMDCs with cocatalysts and the design of multicomponent heterostructures are investigated as methods to promote durability and efficiency. This review emphasizes the central role of TMDCs in developing scalable and sustainable photocatalytic systems for environmental and energy applications.