Low-Energy Photoresponsive Magnetic-Assisted Cleaning Microrobots for Removal of Microplastics in Water Environments

In the global ecosystem, microplastic pollution pervades extensively, exerting profound and detrimental effects on marine life and human well-being. However, conventional removal methods are usually limited to chemical flocculation and physical filtration but are insufficient to remove extremely small microplastics. Therefore, developing a comprehensive strategy to address the threat posed by microplastics is imperative. Here, we report a low-energy photoresponsive magnetic-assisted cleaning microrobot (LMCM) composed of photocatalytic material (Ag@Bi2WO6) and magnetic nanoparticles (Fe3O4), which can be used for the active removal of microplastics from water environments. Due to the diffusion electrophoresis effect, the low-energy photoresponsive cleaning microrobots (LCMs) are formed by spontaneous assembly of Ag@Bi2WO6, which can continuously adsorb microplastics in a water environment. Particularly, the effective attraction distance of LCMs on microplastics exceeds 100 μm. After assembling the Fe3O4 nanoparticles, LMCMs can clean microplastics in groups from water environments under the control of a magnetic field. Utilizing precision manipulation and group control, LMCMs demonstrate a remarkable 98% cleaning efficiency in 93 s and can be recovered under the control of the directional magnetic field. This eco-friendly and energy-efficient microrobot is expected to provide a viable strategy to tackle the threat of microplastics or promote industrial microplastic removal.