Confined Tri-Functional FeO_x @MnO₂ @SiO₂ Flask Micromotors for Long-Lasting Motion and Catalytic Reactions

H₂ O₂ -fueled micromotors are state-of-the-art mobile microreactors in environmental remediation. In this work, a magnetic FeO_x @MnO₂ @SiO₂ micromotor with multi-functions is designed and demonstrated its catalytic performance in H₂ O₂ /peroxymonosulfate (PMS) activation for simultaneously sustained motion and organic degradation. Moreover, this work reveals the correlations between catalytic efficiency and motion behavior/mechanism. The inner magnetic FeO_x nanoellipsoids primarily trigger radical species (^• OH and O₂ ^•- ) to attack organics via Fenton-like reactions. The coated MnO₂ layers on FeO_x surface are responsible for decomposing H₂ O₂ into O₂ bubbles to provide a propelling torque in the solution and generating SO₄ ^•- and ^• OH for organic degradation. The outer SiO₂ microcapsules with a hollow head and tail result in an asymmetrical Janus structure for the motion, driven by O₂ bubbles ejecting from the inner cavity via the opening tail. Intriguingly, PMS adjusts the local environment to control over-violent O₂ formation from H₂ O₂ decomposition by occupying the Mn sites via inter-sphere interactions and enhances organic removal due to the strengthened contacts and Fenton-like reactions between inner FeO_x and peroxides within the microreactor. The findings will advance the design of functional micromotors and the knowledge of micromotor-based remediation with controlled motion and high-efficiency oxidation using multiple peroxides.