Conversion of waste micro/nano plastics into carbon materials: A new trend for renewable energy and environmental applications

Micro- and nanoplastics (MNPs) are emerging contaminants that accumulate in air, water, soil, and biota, where they act as carriers of co-pollutants and pose potential risks to ecosystems and human health. At the same time, their polymer backbones, embedded additives, and high surface-area-to-volume ratios make them intriguing precursors for carbonaceous materials in energy and environmental technologies. In this review, we first examine current methods for detecting and separating MNPs. We then evaluate conversion routes proven on MNPs, including coagulation-assisted carbonization (electrocoagulation and ferric-salt routes), catalytic pyrolysis, hydrothermal carbonization, atmospheric-pressure microwave plasma, and bio-template carbonization methods. Across applications, we summarize how MNP-derived carbons function as supercapacitor and battery electrodes, Fenton-type catalysts, adsorbents, and hydrogen co-production platforms. Finally, we outline major challenges, including feed dilution, process integration with existing treatment infrastructure, toxicity and life-cycle implications of MNP-derived products. By centering MNPs, this review provides a cohesive “detect → separate → convert → apply” framework and practical design rules to accelerate circular, scalable upcycling of the smallest and most problematic plastic fractions.