The Preparation And Function Regulation Of Catalytic Micromotors

Catalytic micro/nano motors is a kind of self-propelled micro/nano scale device which could convert chemical energy to mechanical energy by chemistry catalytic reaction. Over the past decade, researchers have shown increased interest in nano/micro motors. Research on nano/micro motors initially focused on proof of concept. However, thanks to advances in the understanding of motion mechanisms, discovery of new energy sources, and development of procedures for modifying these motors with biological/chemical receptors, research in this area is progressing into specific applications for areas such as biomedicine, environmental monitoring and remediation.The controlled self-assembly of self-propelled Janus micromotors may give the micromotors some potential applications in many fields. In the second section, we design a kind of Pt-SiO2 Janus catalytic micromotor functionalized by spiropyran(SP) moieties on the surface of the SiO2 hemisphere. The spiropyran-modified Pt-SiO2 Janus micromotor exhibits autonomous self-propulsion in the presence of hydrogen peroxide fuel in N,N-dimethylformamide(DMF)/H2O(1:1 in volume) mixture. We demonstrate that the self-propelled Janus micromotors can dynamically assemble into multiple motors because of the electrostatic attractions and π-π stacking between MC molecules induced by UV light irradiation(λ = 365 nm) and also quickly disassemble into mono motors when the light is switched to green light(λ = 520 nm) for the first time. Furthermore, the assembled Janus motors can move together automatically with different motion patterns propelled by the hydrogen peroxide fuels upon UV irradiation. The work provides a new approach not only to the development of the potential application of Janus motors but also to the fundamental science of reversible self-assembly and disassembly of Janus micromotors.In the third section, a water-fueled Au-WO3@C Janus micromotor with light-driven motion and potential for detection and rapid photocatalytic degradation of dyes is described. The Janus micromotors can move at a speed of 16 μm/s under 40 mW/cm2 UV light due to diffusiophoretic effects in aqueous media without addition of any external chemical fuels. Such Au-WO3@C Janus micromotors(diameter ~1.0 μm) have two advantages of repeatable light-controlled motion and long lifetime. Moreover, the speed of the Janus micromotors shows high sensitivity toward extremely low concentrations of sodium-2,6-dichloroindophenol(DCIP) and Rhodamine B(RhB) and can be respectively accelerated to 26 μm/s and 29μm/s in 5×10-4 % DCIP and 5×10-7 % RhB solutions because of enhanced diffusiophoretic effects resulting from photocatalytic degradation of DCIP and RhB. This dye-induced acceleration confirms the self-diffusiophoretic mechanism of the Au-WO3@C Janus micromotor and also offers the micromotors a considerable potential for detection and rapid photocatalytic degradation of dyes in water. The work is particularly of interest for fabrication of light-driven micromotors for potential environmental applications.