Light-driven degradation of microplastics: Mechanisms, technologies, and future directions

The widespread production of plastics has inflicted profound damage on our ecological systems, with microplastics (MPs)–minuscule particles resulting from plastic degradation—emerging as a critical pollutant that negatively impacts living organisms and ecosystems. Conventional methods of plastic disposal are inadequate in effectively mitigating these pollutants. In this context, photocatalytic technology has surfaced as a promising approach for the degradation of MPs. This review offers a comprehensive overview of the mechanisms underlying photocatalytic degradation, thereby enhancing the discourse that follows. Driven by light energy, MPs can undergo two distinct degradation pathways: (1) MPs are mineralized into carbon dioxide (CO 2 ) and water (H 2 O) with the aid of photocatalysts, resulting in complete degradation; (2) MPs can be upgraded and recycled into hydrogen and other valuable compounds through redox reactions and photoreforming processes, offering a cost-effective approach to generating useful products. Additionally, we have refined the classification of photocatalysts, highlighting representative examples such as titanium dioxide (TiO 2 ) and zinc oxide (ZnO) for in-depth discussion, and have systematically summarized the current research trends in this field. Lastly, we address the prevailing technological challenges in the photocatalytic degradation of MPs and propose potential solutions and future research directions, grounded in the current landscape of study.