Construction Of Titanium Matrix Composites And Their Gas Sensing Properties

With the continuous development of industry and agriculture in the world today,serious damage to the ecological environment because the large number of toxic and harmful gases such as NOx,CO,H₂S and VOCs are discharged into our living environment with the continuous development of industry and agriculture in the world.Therefore,it is necessary to develop a gas sensor that can monitor NOx and VOCs gases in real-time.In this paper,Na_0.23TiO₂/TiO₂ nanotube composites were prepared by a simple hydrothermal method and loaded with different concentrations of SnO₂ to form SnO₂/TiO₂ nanotube composites.The research content of this paper is as follows:1.The Na_0.23TiO₂/TiO₂ composites are synthesized by different concentrations of alkali as well as hydrothermal time.The composition and morphology of the samples are characterized and the formation mechanism of the composites are explored.After hydrothermal treatment the sample was transformed from the original particles to the multi-walled tubular structure.The diameter of the nanotube is 10 nm,the wall thickness is 3 nm,and the layer spacing is 0.8 nm.The Na_0.23TiO₂/TiO₂ nanotubes have a large specific surface area(99.3 cm~2/g)and an abundant mesoporous structure.The gas-sensitive test of the samples revealed that the samples hydrothermal for 72 h with10 M NaOH solution had the best gas-sensitive performance to NOx.The response value of Na_0.23TiO₂/TiO₂ to 50 ppm NOx gas could reach 40.3 at room temperature,and Na_0.23TiO₂/TiO₂ also has good selectivity and long-term stability.The excellent gas-sensitive performance of Na_0.23TiO₂/TiO₂ nanotubes to NOx is mainly attributed to the formation of the p-n heterojunction,hollow multi-walled tubular structure,abundant pore channels and large specific surface area of the material species,which provide more active sites for Na_0.23TiO₂/TiO₂ nanotubes.2.SnO₂/TiO₂ nanotube composites are based on Na_0.23TiO₂/TiO₂ nanotube composites by ultrasonic and stirring loading of SnO₂.The morphological structure of the material and testing the gas-sensitive properties are carried out.The SnO₂/TiO₂nanotubes retained the tubular structure of the precursor during the synthesis and preparation,and the specific surface area of the material increased to 130.8 cm~2/g after loading with SnO₂,and the chemisorbed oxygen on the surface increased.The response value of SnO₂/TiO₂ nanotube composites prepared in 0.015 M Sn Cl4 solution to 100ppm n-pentanol is 24.3 and has a faster response and recovery time at room temperature.The enhanced gas-sensitive performance of the SnO₂/TiO₂ nanotube composites for n-pentanol can be attributed to the retention of the tubular structure and the formation of n-n heterojunctions in the material.