Integrated photothermal and photocatalytic degradation of micro-/nanoplastics: a mini-review with mechanistic insights and future perspectives

Abstract

The growing threat of micro- and nanoplastics (MNPs) demands urgent development of eco-friendly and sustainable treatment technologies. Traditional approaches including mechanical filtration, enzymatic degradation, and chemical treatments face challenges—low efficiency, high costs, and toxic byproducts. In contrast, solar-driven methods, especially photothermal (PT) and photocatalytic (PC) degradation, offer cleaner alternatives. This mini-review explores recent advances over the past five years, combining these two methods: photothermal heating speeds up photocatalytic reactions, while photocatalysis prevents harmful byproducts from undergoing incomplete plastic breakdown, emphasizing their mechanisms and importantly the potential of their synergistic integration, which significantly enhances the degradation performance. Furthermore, engineered materials—such as plasmonic nanoparticles, graphene oxide hybrids, and modified titanium dioxide composites—are systematically compared for their performance, stability, and scalability. As a state-of-the-art material, photothermal–photocatalytic (PT–PC) composites have achieved a remarkable photothermal conversion efficiency with high evaporation rates under sunlight along with full upcycling of plastic pollutants and promising recyclability—rendering it a potential system for MNP degradation by significantly lowering energy barriers compared to heat or light alone. Despite progress, challenges persist in scaling these technologies, ensuring material durability under real-world conditions and achieving complete plastic degradation. To bridge the lab-to-industry gap, future efforts must prioritize three goals: (1) designing low-cost, multifunctional catalysts that harness both PT and PC effects; (2) optimizing sunlight utilization; and (3) validating prototypes through pilot-scale demonstrations with real environmental samples. Collaborative research across materials science, chemical engineering, and environmental monitoring will be critical to translating these innovations into practical solutions.