Magneto-Propelled Micromotors for Integrated Capture and Catalytic Upcycling of Micro/Nanoplastics.

The pervasive accumulation and recalcitrance of micro/nanoplastics in ecosystems pose severe environmental and health challenges, demanding innovative solutions that integrate remediation with resource recovery. In this study, we report magnetically driven Au nanoparticles/helical-Mn/N-doped carbon nanotubes (AMNC) micromotors engineered for the integrated capture, time-resolved monitoring, and catalytic upcycling of polystyrene (PS) micro/nanoplastics. The AMNC micromotors achieve near-complete degradation of PS, producing valuable benzoic acid with a yield of approximately 60%. The dynamic motion of micromotors under a magnetic field enables active enrichment of micro/nanoplastics, while the electromagnetic "hot spots" at the Au-micromotor interface enable sensitive, in situ surface-enhanced Raman scattering (SERS) tracking with a detection limit of 0.17 µg/mL. Mechanistic studies reveal that N-doping and manganese carbide species synergistically enhance peroxymonosulfate activation and electron transfer, with density functional theory calculations identifying the SO4 •‒-mediated attack on the PS backbone as the rate-determining step. The system demonstrates robust performance across diverse water matrices and under scale-up conditions, with a machine learning model (R2 = 1.0) accurately predicting degradation efficiency. Techno-economic analysis confirms the economic viability of the process and a significantly reduced environmental footprint. This intelligent platform integrates pollution control with value-added conversion for sustainable plastic waste management.