Fish-Scale-Like Intercalated Metal Oxide-Based Micromotors as Efficient Water Remediation Agents

With compelling virtues of a large specific surface area, abundant active sites, and fast interfacial transport, nanomaterials have been demonstrated to be indispensable tools for water remediation applications. Accordingly, micro/nanomotors made by nanomaterials would also benefit from these properties. Though tuning the surface architecture on demand becomes a hot topic in the field of nanomaterials, there are still limited reports on the design of active surface architectures in chemically driven tubular micro/nanomachines. Here, a unique architecture composed of a fish-scale-like intercalated (FSI) surface structure and an active layer with 5 nm nanoparticles is constructed, which composes of Fe<sub>2</sub>O<sub>3</sub> and ramsdellite MnO<sub>2</sub>, Mn<sub>2</sub>O<sub>3</sub>, in the tubular micromotor using a versatile electrodeposition protocol. Tailoring the electrodeposition parameters enables us to modulate the active MnO<sub>2</sub> surface structure on demand, giving rise to a pronounced propulsion performance and catalytic activity. Upon exposure to the azo-dye waste solution, the degradation efficacy greatly raises by around 22.5% with FSI micromotor treatment when compared to the normal compact motors, owing to the synergistic effect between the Fe-related Fenton reaction and a large catalytic area offered by the hierarchically rough inner surface. Such unique micromachines with a large active surface area have great potential for environmental and biomedical applications.