Micromotor-assisted highly efficient Fenton catalysis by a laccase/Fe-BTC-NiFe2O4 nanozyme hybrid with a 3D hierarchical structure

Abstract

Self-propelled micro- and nanomotors are a current research focus and have shown attractive potential in environmental applications. Here, we report a biomass approach to construct a novel tubular micromotor decorated with a nanozyme/natural enzyme hybrid, which integrated the advantages of the self-propelled movement, selectivity of a natural enzyme and catalytic activity of artificial nanozymes. Such a micromotor had a unique hierarchical structure where laccase immobilized-Fe-BTC MOF nanoparticles grew uniformly on Mn₂O₃–NiFe₂O₄ nanosheets, which was constructed using natural kapok fiber as a template. This laccase-integrated Fe-BTC/NiFe₂O₄ micromotor was capable of self-propulsion with a speed of 120 μm s⁻¹ by oxygen bubbles via the decomposition of H₂O₂ catalyzed by Mn₂O₃. Owing to the incorporation of autonomous motion with high selectivity of natural laccase and high peroxidase-like activity of the Fe-BTC/NiFe₂O₄ nanozyme, these micromotors exhibited much higher catalytic activity to methylene blue degradation than their passive counterparts. Besides as a substrate to accommodate laccase immobilized-Fe-BTC, magnetic NiFe₂O₄ also enabled the remote magnetic control on the movement direction.