Light-controlled bubble propulsion of amorphous TiO2/Au Janus micromotors

Abstract

In this work, a bubble-propelled photoactivated amorphous TiO₂/Au (Am-TiO₂/Au) Janus micromotor has been demonstrated by utilizing the efficient photocatalytic H₂O₂ decomposition over the in situ H₂O₂ sensitized Am-TiO₂ under UV irradiation. The power conversion of the micromotor experiences a process from UV light power, to chemical power and finally to mechanical power. The quantum efficiency of O₂ bubble evolution from photocatalytic decomposition of H₂O₂ reaches 28%, and the power conversion efficiency reaches 1.28 × 10⁻⁹, which enables the micromotor to generate a strong bubble thrust propelling itself forward with a maximum speed of 135 μm s⁻¹. The motion state and speed of the Am-TiO₂/Au micromotors can be reversibly, wirelessly and remotely controlled at will with an ultrafast response rate (less than 0.1 s) by regulating “on/off” switch and intensity of UV irradiation. Consequently, the as-developed Am-TiO₂/Au micromotors may promise potential challenging applications in such as “on-the-fly” adsorption and decomposition of pollutants in water.