Electrochemical Deposition Tailors the Catalytic Performance of MnO2-Based Micromotors

Artificial micro/nanomotors that could perform diverse tasks autonomously at the micro/nanoscale have been emerging as promising tools in many practical applications. Electrochemical synthesis is one of the dominating methods to fabricate these micro/nanodevices with diverse geometries and material components. By changing the conditions of electrochemical deposition, the surface morphology, crystal structure, and hence the resultant performance of deposited material could be tailored. In the current work, a feasible fabrication strategy is presented in terms of three unique electrodeposition types (i.e., potentiodynamic, potentiostatic (PS), and galvanostatic) to synthesize different MnO2-based micromotors. Distinct propulsion behavior as well as the catalytic degradation of azo-dye organic waste (with methylene blue as the representative), between three kinds of MnO2-based micromotors is clearly displayed, owing to the distinctive chemical composition and morphology designs. The activated R-MnO2-based micromotors in PS mode exhibit fast motion speed (up to 12 body length per second), leading to the highest degradation efficiency. Such propulsion performance is comparable with the microrockets made by noble metals such as Pt and Ag. The new protocol will have a profound impact on the design of synthetic micro/nanomotors and hold a considerable promise for their diverse applications.