Preparation Of Gas Sensitive Materials Based On Titanium Dioxide Nanotubes And Its Performance Research

With the development of the scientific and technological society and the continuous improvement of human living standards,environmental pollution has become more and more serious.As one of the main culprits of environmental pollution,NO₂ can cause acid rain and photochemical smog,which seriously threaten the living environment on which humans depend and endanger people’s health.Therefore,the preparation of high-performance NO₂sensors has become a hot spot for researchers.Among them,sensitive materials are the key to determine the sensitivity of gas sensors,and sensitive materials with excellent preparation performance are effective ways to improve gas sensitivity.Titanium dioxide is an ideal material for building room temperature gas sensors because of its non-polluting,high room temperature carrier mobility and low electrical noise.Compared with other metal oxide semiconductor gas sensors,the titanium dioxide-based gas sensor has a simple preparation process and is inexpensive,and can be applied to gas sensors and the like in a large scale.In view of the current poor sensitivity of titanium dioxide based room temperature gas sensors,this thesis aims to develop high performance room temperature NO₂ gas sensors,and explore the different types of modification on the surface of sensitive materials to improve their gas sensitivity characteristics,and optimize the sensitive materials.Synthetic conditions,reasonable control of the surface and interface of the material,thereby improving the sensitive characteristics of the sensor,and obtaining some meaningful research results.The main research work of this paper has the following aspects:（1）Non-metal monoatomic doped titanium dioxide nanotubes:The self-prepared carbon fiber nanowires were used as template materials,and the TiO₂ thin layer was hydrolyzed on the surface of carbon fiber nanowires by sol-gel chemical method.Finally,the carbon fiber nanowire template was obtained by calcination.The C-doped tubular high oxygen vacancy TNT was removed,thereby obtaining a C-TNT composite having a high oxygen vacancy concentration.The introduction of high concentration oxygen vacancies enhances the electrical properties and chemical catalytic activity of sensitive materials,so that it has a stronger adsorption capacity for NO₂,thereby improving the gas sensing properties of the sensor.（2）Non-metallic compound modified titanium dioxide nanotube array:Using titanium dioxide nanotube arrays（TNTs）as sensitive material matrix,C₃N₄ quantum dots（C₃N₄QDs）and reduced graphene oxide（rGO）were respectively treated by chemical vapor method and electrochemical reduction method.The surface of the TNTs is modified to finally obtain a Schottky junction composite.The TNTs/C₃N₄QDs/rGO composites have high surface oxygen vacancy concentration,which confirms that the surface microstructure of the material has an effect on the gas sensing performance of NO₂,which provides a new idea for the development of high performance TiO₂ gas sensors.（3）Organic small molecule modified titanium dioxide nanotube array:Organic small molecule modified metal oxide semiconductor is an effective sensitization method.Firstly,the surface of TNTs was modified with cadmium sulfide quantum dots（CdSQDs）,and the sensitivity of the sensor was enhanced by the electronic sensitization and catalysis of CdSQDs.Subsequently,the surface of TNTs/CdSQDs was modified by chemical hydrolysis.Based on triethoxysilane（APTES）,ternary TNTs/CdSQDs/APTES composites were constructed,and the synergistic effects of the three components further enhanced the sensitivity of TNTs to NO₂.