Engineered nanocatalysts for degradation and valorisation of micro/nanoplastics

Transforming plastic waste into value-added products is central to advancing a circular economy and reducing the escalating burden of micro/nanoplastic (MP/NP) pollution. These emerging contaminants infiltrate freshwater, marine, and soil environments, posing serious ecological/toxicological risks. MP/NPs alter the environment-health nexus, and their smaller size, hydrophobicity, and persistence make them difficult to mitigate; thus developing effective degradation strategies has become crucial. The catalytic degradation mechanism has gained attention as a promising alterative capable of reforming persistent MP/NP pollutants into valuable products and fuels. Owing to their tunable physicochemical properties, engineered nanocatalysts offer efficient charge separation, selective bond cleavage and energy-efficient transformation of MP/NPs. This review provides a comprehensive overview of catalytic pathways governing nanocatalyst-mediated degradation of MP/NPs, along with a framework for designing advanced engineered nanocatalysts including microrobots, micromachines, MXenes, nanozymes and engineered organic framework-based catalysts. Further, the review focuses on utilization of these advanced nanocatalysts as green and sustainable approaches for efficient degradation/valorisation of MP/NPs. The practical feasibility is evidenced through recent real-world applications such as solar photopanels, seawater-deployable floaters and self-powered nanogenerator systems. Notably, the influence of nanocatalyst morphology on the degradation efficiency of MP/NPs has also been evaluated. Finally, the review evaluates the scale-up potential of engineered nanocatalysts and the applicability of high value products, supporting the translation of engineered nanocatalysts into practical, circular-economy-driven plastic waste solutions. Overall, this review reframes micro- and nanoplastic remediation from conventional degradation to catalytic valorisation, guided by mechanistic insights and advanced nanocatalyst design for real-world implementation.