High-performance carbon/MnO micromotors and their applications for pollutant removal.

The wide applications of particulate micromotors in practice, especially in the removal of environmental pollutants, have been limited by the low production yields and demand on high concentration of fuel such as HO. Carbon/MnO micromotors were made hydrothermally using different carbon allotropes including graphite, carbon nanotube (CNT), and graphene for treatment of methylene blue and toxic Ag ions. The obtained micromotors showed high speed of self-propulsion. The highest speed of MnO-based micromotors to date was observed for CNT/MnO (>2 mm/s, 5 wt% HO, 0.5 wt% surfactant). Moreover, different from previous studies, even with low HO concentration (0.5 wt%) and without surfactant addition, the micromotors could also be well dispersed in water by the O stream released from their reaction with HO. The carbon/MnO micromotors removed both methylene blue (>80%) and Ag ions (100%) effectively within 15 min by catalytic decomposition and adsorption. Especially high adsorption capacity of Ag (600 mg/g) was measured on graphite/MnO and graphene/MnO micromotors.