Modulating ion migration realizes both enhanced and long-term-stable nanozyme activity for efficient microplastic degradation.

Degradation of microplastics represents a significant global environmental challenge, necessitating the development of bio-inspired catalysts with superior activity and stability, capable of mimicking natural plastic-degrading enzymes. Although nanozymes possess advantages such as low cost, ready availability, and multienzymatic activities, issues of self-consumption often hinder their practical application. Here, motivated by the acceleration of Li migration for improving the electrochemical reactivity and cycling stability of lithium iron phosphate (LFP), we engineered LFP by introducing Mn to expand the lattice structure, resulting in Mn-doped LFP (LFMP) that modulates ion migration in nanozymes. Density functional theory (DFT) calculations reveal that Mn doping expands the lattice structure of LFP while narrowing its bandgap, thereby significantly enhancing Li migration rates. Leveraging this design, LFMP exhibits enhanced peroxidase-like activity (3 times higher than that of LFP) and cycling stability (80% activity retention after 5 cycles 45% for LFP), enabling efficient degradation of microplastics made from polyamide 6, high-density polyethylene, and polypropylene. By exemplifying that the degradation efficiency achieved using LFMP nanozymes significantly exceeds that of traditional methods, we affirm that lattice expansion-driven ion migration may inspire future strategies to circumvent the self-consumption issue while maintaining high catalytic activity in nanozymes.