Catalytic Pollutant Upgrading to Dual-Asymmetric MnO 2 @polymer Nanotubes as Self-Propelled and Controlled Micromotors for H 2 O 2 Decomposition.

Industrial and disinfection wastewater typically contains high levels of organic pollutants and residue hydrogen peroxide, which have caused environmental concerns. In this work, dual-asymmetric MnO 2 @polymer microreactors are synthesized via pollutant polymerization for self-driven and controlled H 2 O 2 decomposition. A hollow and asymmetric MnO 2 nanotube is derived from MnO 2 nanorods by selective acid etching and then coated by a polymeric layer from an aqueous phenolic pollutant via catalytic peroxymonosulfate (PMS)-induced polymerization. The evolution of particle-like polymers is controlled by solution pH, molar ratios of PMS/phenol, and reaction duration. The polymer-covered MnO 2 tubing-structured micromotors presented a controlled motion velocity, due to the reverse torque driven by the O 2 bubbles from H 2 O 2 decomposition in the inner tunnels. In addition, the partially coated polymeric layer can regulate the exposure and population of Mn active sites to control the H 2 O 2 decomposition rate, thus avoiding violent motions and massive heat caused by vigorous H 2 O 2 decomposition. The microreactors can maintain the function of mobility in an ultra-low H 2 O 2 environment (<0.31 wt.%). This work provides a new strategy for the transformation of micropollutants to functional polymer-based microreactors for safe and controlled hydrogen peroxide decomposition for environmental remediation.