Research On The Preparation Of TiO₂/mSiO₂ Micro/nano-structures And Their Application As Self-propelled Motors

Micro/nanomotors are devices in micro/nanoscale that can convert external energies such as chemical,light or acoustic energy into kinetic energy to drive motor motion.The advanced feature of autonomous locomotion confers the micro/nanomotors great potentials in the applications of cargo delivery,biomedicine and environmental protection,etc.This thesis will focus on the fabrication of titanium dioxide（TiO₂）and mesoporous silica dioxide（mSiO₂）based micro/nanostructures which are further processed into micro/nanomotors by combining with various driving mechanisms.The TiO₂@mSiO₂ bilayer composite tubular motors can achieve environmental monitoring and environmental remediation simultaneously,thus pave a new way for MNMs in environmental applications.In this work,we designed and prepared spherical and tubular micro/nanostructures based on TiO₂/mSiO₂.The morphology,structure and crystal phase were characterized by scanning electron microscope（SEM）,transmission electron microscope（TEM）and X-ray diffractometer（XRD）.The Au/TiO₂ Janus spherical motor was prepared by sputtering gold on the surface of the calcined anatase TiO₂ sphere,which was driven by photocatalysis under ultraviolet light.By depositing pre-prepared platinum nanoparticles in the tubular structure,motors driven by oxygen bubbles through platinum catalytic decomposition reaction were obtained.Aiming at the problem that micro/nanomotors in environmental applications cannot achieve environmental monitoring and environmental remediation at the same time,this topic combined the preparation methods of TiO₂ tube and mSiO₂tube,to prepare a TiO₂@mSiO₂ bilayer tubular motor with the outer layer of mSiO₂and the inner layer of TiO₂.Then we deposited magnetic Fe₃O₄ nanoparticles inside for magnetic recovery of the motors.Because of the excellent adsorption capacity of the mSiO₂,the adsorption capacity of the bilayer tube for rhodamine 6G is 3-4 times stronger than that of the pure TiO₂ tube,so the outer mSiO₂ layer of the bilayer tube can be used as the collection functional layer of pollutant.The outer mSiO₂ layer in the bilayer tubular motor is used to adsorb and collect the simulated pollutants.After the magnetically recovery of the motors,the collected pollutants are determined by SERS and other analytical technologies to initially realize the environmental pollutant monitoring function of the motor.And the motor exhibit excellent degradation ability of pollutants by combined effect of the photocatalysis of inner TiO₂ layer under ultraviolet light,the free radical produced by H₂O₂ and the micro-stirring produced by the motor’s movement.In the experiment of this thesis,the motor under ultraviolet light irradiation can degrade more than 98%of rhodamine 6G in 30 min,realizing the environmental remediation function of the motor.Therefore,based on the sol-gel method and template method,we have prepared different micro/nanostructures and processed them into the self-propelled motors.The application of TiO₂@mSiO₂ bilayer tubular motor in the environmental field was further studied.This motor successfully realized two functions simultaneously,including pollutant collection and detection（environmental monitoring）,as well as pollutant degradation（environmental remediation）.Therefore,the bilayer tubular motor prepared in this thesis lays a foundation for the future development of multi-functional and intelligent environment-governance motors.