Symmetric Catalytic Pt-MnO2@Carbon Microspheres as Micromotors for Dynamic Pollutant Remediation

Organic pollutants in water pose a serious risk to public health, hence, it is essential to develop new and innovative approaches to the remediation of contaminated water. This work demonstrates a highly effective bubble-propelled micromotor based on the surface coating of symmetrical carbon microspheres (CMSs) with catalytic manganese dioxide (MnO 2 ) nanoflakes and platinum nanoparticles (Pt NPs) (Pt-MnO 2 @CMS). This concept represents a simple and flexible strategy for the decomposition of organic pollutants in water and could be used to construct a wide range of diverse micromotors with applications in drug delivery, sensing, energy generation and environmental remediation. The unique hierarchical structure of the MnO 2 nanoflakes and the uniform dispersion of Pt NPs in this material were confirmed. The resulting micromotors were found to move rapidly as a result of propulsion by oxygen bubbles generated in a H 2 O 2 solution via the catalytic actions of the MnO 2 nanoflakes and Pt NPs. In contrast to the intrinsic asymmetry of tubular and Janus structures, the self-driven motion of these symmetrical micromotors can be attributed to morphological variations and the uneven distribution of the cocatalysts. Combining a porous structure, rapid movement and Fenton-like reactions, these Pt-MnO 2 @CMS micromotors rapidly degraded methylene blue (MB), providing greater than 99% decolorization in just 30 min without the need for external agitation. Analyses of the adsorption mechanism based on pseudo-first-order and pseudo-second-order kinetics models showed that adsorption proceeded via chemical processes. These new micromotors are expected to have important environmental and biomedical applications.