Light-controlled two-dimensional TiO 2 plate micromotors.

In this work, UV light-controlled two-dimensional (2D) TiO 2 plate micromotors are demonstrated for the first time. The 2D TiO 2 micromotors are produced by the well-known anodic oxidation method in combination with a cracking and separation process. When the motor is placed in H 2 O 2 aqueous solution under UV irradiation, oxygen bubbles are generated in the holes of the TiO 2 membrane. The 2D micromotor thus moves upon O 2 bubbles under its own weight. In contrast to bubble-propelled micromotors, which require an addition of surfactants to chemical fuels, the 2D micromotor is capable of moving in aqueous H 2 O 2 solution without surfactants. Moreover, speed of the 2D TiO 2 micromotor can be controlled by the intensity of the UV light. Such surfactant-free micromotors and their facile fabrication hold considerable promise for diverse practical applications in the biomedical and energy fields, for example, and in new materials.