TiO2@carbon Microsphere Core–shell Micromotors for Photocatalytic Water Remediation

Photocatalytic micromotors hold considerable promise for use in water remediation owing to the synergistic effect of a combination of photocatalytic activity and self-propulsive behavior. We designed a symmetric TiO2@carbon microsphere (CMS) core-shell micromotor with photocatalytic TiO2 for enhanced degradation of organic contaminants. TiO2@CMS micromotors were obtained via a facile sol-gel method and subsequent heat treatment to obtain an anatase TiO2 shell. The self-propulsion of TiO2@CMS micromotors is governed by asymmetric decomposition of H2O2 via asymmetric illumination of the spherical particles. The photocatalytic propulsion can be switched on and off by modulating the incident light. The speed of the photocatalytic TiO2@CMS core-shell micromotors can be increased by increasing either the light intensity or concentration of the chemical fuel, i.e., H2O2. In the degradation of rhodamine B, the photocatalytic performance of the micromotors was higher than those achieved with control group photocatalysts. The degradation efficiency reached similar to 100% in approximately 60 min when all necessary conditions, i.e., use of micromotors, UV irradiation, and H2O, were applied. TiO2@CMS core-shell micromotors have the advantages of facile preparation, a simple structure, self-propulsion, and a high degradation efficiency and photocatalytic performance. They will therefore be important in the development of methods for water purification and wastewater treatment.