Preparation And Investigation On Its Surface Driving Performance Of TiO₂-based Micro/nano Motors

A Micro-Nano Motor is a micro or nano scale device that converts energy into movement and force which inhere huge potential for both biomedical and environmental applications where motion can be induced by different energy sources including light,magnetic,and electric fields,ultrasonic waves,or chemical fuels.Among them,chemically powered micro-nano motor governed by the bubble-recoil mechanism and other propulsion mechanisms have been extensively studied,both for their motion mechanisms and improved mixing effects observed during their motion.For the bubble-driven micro-nano motor,the driving force of the motor is caused by the recoil force on the motor which caused by the release of the bubble generated by the redox in the(photo)catalytic reaction on the surface of the motor substrate.In the catalytic solution system,the characteristics of contact interface the solid(motor substrate)and liquid(fuel solution)play an important role in bubble separation,and then bubble separation is a key factor for effective propulsion.Changing liquid phase such as addition of surfactants and increasing fuel concentration is a common method to achieve effective propulsion,but it also brings many disadvantages and restriction.We noticed that the long-term retention of bubbles will decrease solid-liquid contacting area,with occupying the active sites of catalysis on the surface of motors and limited catalytic activities of the reaction,which will affect the driving efficiency of the motor to some extent.Therefore,the unique "superaerophobic" solid phase may solve this problem effectively.In this work,by preparation of a single-sided Ti/TiO2-Pt nanowires network,a bubble-propelled micro-nano motors network was constructed.In comparison to underwater aerophilic substrateloaded Pt,which pin bubbles strongly,Ti/TiO2-Pt nanowires network showed great aerophobicity which exposing the activity sites of the catalysis to the catalytically reaction provides a strong technical supporting for improving the efficiency of the catalytic reaction and promoting the continuous and efficient generation and detachment of the O2 bubble to improve the moving speed of the motor.Especially,after UV illumination for 30 s,the superaerophobicity of sbstrate has been trigged,which promoted the releasing process of O2 bubbles.Based on this result,we believe that it will be highly significant to provide guidance for the strategy of obtaining more efficient operation of micro-nano motor by controlling the behavior of bubble detachment by controlling aerophobic behaviors of solid surface of autonomous micro-nano motor in a water medium.