Biomass-derived 3D hierarchical Zr-based tubular magnetomotors with peroxidase-like properties for selective colorimetric detection and specific decontamination of glyphosate at neutral pH

Abstract

Multifunctional micro/nanomotors that can sensitively detect and rapidly remove pollutants have attracted growing attention in environmental monitoring and remediation. Herein, we present a bioinspired hierarchical ZrO₂/MnFe₂O₄/FeZr-MOF tubular magnetomotor with peroxidase-like activity as an active and smart platform for simultaneous colorimetric detection and specific purification of trace hazardous glyphosate under neutral conditions in complex environmental matrices. The well-designed Zr-containing micromotors were composed of ZrO₂ microtubes acting as a support and MnFe₂O₄ nanosheets functioning as a catalyst and magnetic guide, as well as FeZr-MOF octahedrons with intrinsic peroxidase-like activity, constructing a unique hierarchical architecture with abundant exposed reactive sites. The chemically powered microrobots could autonomously move in a circle-like motion pattern via O₂ bubbles generated from the MnFe₂O₄-catalyzed decomposition of H₂O₂ with a velocity of 101.6 ± 10.2 μm s⁻¹ in 5% H₂O₂. Benefiting from the combination of autonomous motion, the powerful affinity between Zr–O clusters and phosphate groups, and the robust peroxidase-like activity, the resulting dynamic Zr-based micromotors achieve the specific capture and adsorption of glyphosate with a LOD of 0.05 mg mL⁻¹ and a maximum adsorption capacity of 313.5 mg g⁻¹. In particular, the microdevices enabled the colorimetric detection of glyphosate at neutral pH, which may be ascribed to the acidic microenvironment generated from the oxygen-containing groups in the micromotors. This study provides a promising pathway for the rational construction of multifunctional microcleaners for simultaneous determination and removal of organic pollutants from wastewater.