Photocatalytic strategy to mitigate microplastic pollution in aquatic environments: Promising catalysts, efficiencies, mechanisms, and ecological risks

As a type of emerging pollutants, microplastics (MPs) are widely detected in aquatic environments and attract increasing ecological concern worldwide. The mitigation strategy of MPs pollution in aquatic environments has thus become a research priority. Photocatalysis has recently received wide attention largely due to its high potential for MPs degradation. However, to gain an in-depth and comprehensive understanding of photocatalysis in MPs mitigation, we reviewed the up-to-date advancements regarding the key parameters for evaluating the photodegradation, promising photocatalysts, and key mechanisms; possible synergistic reactions were also illustrated. Especially, the modification of photocatalyst was analyzed and interpreted for improving the performance including doping metal, decorating functional group, etc. The relationship between the reactive oxygen species generation and the material structure was elucidated. Moreover, the ecological risks induced by photocatalysis were discussed. To take it a step further of today's photocatalysis in MPs degradation, future research should focus on (1) designing realistic photocatalytic materials to improve the efficiency of MPs degradation; (2) detailing the degradation mechanisms and synergistic reactions to better utilize the advantages of photocatalysis; and (3) quantitatively evaluating the ecological risks posed by the degradation intermediates and further developing recycling approaches.