Noble Metal-tio <sub> 2 </ Sub> Nanocomposite Electrode Preparation And Bio-electrochemical Sensing Performance Study

Nano-sized TiO₂ is one of the most promising semiconductor photocatalysts because of its superior photocatalytic activity, high photocatalytic efficiency, nontoxicity, and strong oxidizing ability. And the application of nano-sized TiO₂ has attracted much attention in the field of bioelectrochemistry. However, how to synthesize anatase TiO₂ with high crystallinity and large surface area is key point to gain high sensitivity enzyme bioelectrochemistry sensing property. Nano-sized TiO₂ with high crystallinity, large surface area and high charge transfer capacity were designed and synthesised by surface-modificating meso-porous SiO₂ and compositing with CNTs, and the bioelectrochemistry electrode was constructed by photoreduction depositing noble metal Au and immobilizing active enzyme, as well as the influence of the structure characteristic on electrochemical sensing properties were also mainly investigated, moreover, the process mechanism and inner influencing factors were revealed by photocatalytic process, SPV technique, electrochemical impedance spectra and cyclic voltammetry, which should provide dependencies and directions for constructing novel bioelectrochemistry. As follows:Nanocrystalline anatase TiO₂ was obtained by a sol-hydrothermal process, In order to further improve crystallization degrees of the nanocrystalline anatase TiO₂, while maintaining its large surface area, the investigation on sol-hydrothermal synthesis of nanocrystalline anatase TiO₂ surface modification was carried out. The results show that the surface modification significantly improves the thermal stability and crystallization degree of nano-sized TiO₂, at the same time conduces to the maintenance of small size. High crystallization degree is favor to improve the charge separation and transport. Therefore, the enhanced crystallization degree and the maintained surface area decide that the appropriate modified mesoporous silica TiO₂ nanoparticles can display high photocatalytic activity. High crystallization degrees and large surface area of nano-sized TiO₂ provides the foundation for the design and synthesis of the enzyme sensor to build high-performance electrode materials. The results of electrochemical impedance spectra and cyclic voltammetry can further confirm that the structural characteristics of TiO₂ nanoparticles with high crystallization degrees and large surface area is propitious to enhance the immobilization of the biological activity enzyme and the charge transfer capabilities, thus significantly improving the sensor performance of the TiO₂-based bioelectrochemical substrate electrode.Furthermore, a simple Synthesis method of one-pot two-phase-separated hydrolytic-hydrothermal process was developed. The method without any following calcination can directly synthesized the TiO₂ nanoparticles with fewer defects, high crystallization degree and excellent photocatalytic activity, namely it can own the good electron-transfer capacity. Moreover, titanium dioxide-based nano-materials with better photocatalytic activity and electron-transfer capacity were obtained by the effective compound of carbon nanotube and nano-titanium dioxide directly and controllable, so that its novel bioelectrochemical composite electrode could reveal good Bio-sensing properties. The work should afford the practical and theoretical principle for design and synthesis of high capable enzyme sensor.