MOF-derived magnetic microrobots for the active capture of nanoplastics

Abstract

The widespread use of synthetic polymeric products in modern life has led to an uncontrolled presence of micro-/nano-plastics in the ecosystem. Tiny plastic debris are now commonly found in water bodies, posing potential threats to the well-being of living organisms. Among various water remediation methods, adsorption stands out as a safe and effective strategy for removing micro-/nano-plastics because it avoids the release of toxic by-products. However, diffusion-limited interactions complicate the practical implementation of this approach. Herein, we adopted a microrobotic approach to actively and selectively collect nanoplastics from aqueous solutions. As a model system, we utilized microrods derived from iron-based metal–organic frameworks (Fe-MOFs) as magnetically actuated microrobots to remove polystyrene nanobeads. For microrobot fabrication, we employed a two-stage strategy, in which the Fe-MOF structures are carbonized to form the porous FeO_x@C microrods. Structural and morphological studies confirmed the successful fabrication of hexagonal microrods with an intrinsic magnetic behavior and surface-active sites. Under rotating magnetic fields, the FeO_x@C microrods (MILBots) demonstrated externally controllable locomotion, enabling the active removal of nanoplastics from aqueous solutions. Such a microrobotic approach could pave the way for externally controllable water remediation.