Fabrication And Research Of Gas Sensor Based On Independent TiO₂ Nanotube Array

As a chemical substance,ethanol plays an important role in food industry and energy industry.In the process of ethanol production,how to accurately monitor the concentration of ethanol is of great significance to the industrial production of ethanol.A semiconductor ethanol gas sensor was developed and its response to high concentration ethanol gas was studied.The sensor was made of TiO₂ with independent nanotube arrays.Firstly,TiO₂nanotube array was prepared by electrochemical anodizing in the electrolytic liquid system of NH₄F-glycol and water,and the influence of oxidation voltage,oxidation time and water content in the electrolyte on the microstructure of TiO₂ nanotube array was studied in this paper.Secondly,the independent type of TiO2 nanotube arrays stripping process was studied.After anodic oxidation,TiO₂ nanotube arrays was annealed under a certain temperature conditions and then subjected secondary anodic oxidation to get independent type of TiO₂ nanotube arrays,the process involved in the influence of heat treatment temperature and time on the stripping process were studied.The results showed that the stripping could be completed by secondary anodic oxidation for 1.5h after heat treatment at 400℃for 40min.When heat treatment conditons was 500℃and 600℃for 2h,the secondary oxidization time was 1h to complete the peeling.In this paper,dispersed and independent gas sensors were fabricated based on the detached independent TiO₂ nanotube array and the high-concentration ethanol gas was detected.The experimental results show that the sensitivity of the whole gas sensor is4.17 when the concentration of ethanol is 30%,and 13.05 when the concentration of gas is 90%.The response-recovery time was 21s and 15s,respectively,The best working temperature is around 250℃.Due to the dispersion of the nanotube structure,the sensitivity of the dispersed gas sensor is greatly improved compared with that of the whole sensor.The sensor sensitivity increased to 23.07 when the concentration of ethanol gas was 30%,50.02 when the concentration of gas was 90%,and the response-recovery time is 29s and 19s,respectively.The best working temperature is around 250℃.