Magnetically steerable iron oxides-manganese dioxide core-shell micromotors for organic and microplastic removals.

Because of micro/nanoscale manipulation and task-performing capability, micro/nanomotors (MNMs) have attracted lots of research interests for potential applications in biomedical and environmental applications. Owing to the low-cost, good motion behavior, and environmental friendliness, various low-cost metal oxides based MNMs become promising alternatives to the precious metal based MNMs, in particular for environmental remediation applications. Hereby, we demonstrate the facile and scalable fabrication of two types of bubble-propelled iron oxides-MnO2 core-shell micromotors (Fe3O4-MnO2 and Fe2O3-MnO2) for pollutant removal. The Fe2O3-MnO2 micromotor exhibits efficient removals of both aqueous organics and suspended microplastics via the synergy of catalytic degradation, surface adsorption, and adsorptive bubbles separations mechanisms. The adsorptive bubbles separation achieved more than 10% removal of the suspended microplastics from the polluted water in 2 h. We clarified the major contributions of different remediation mechanisms in pollutants removals, and the findings may be beneficial to a wide range of environmental applications of MNMs.