Study On Ethanol Sensing Properties Of The SnO₂-doped TiO₂ Thick Film Prepared By Sol-gel Method

Ti O2 as a semiconductor material, belongs to the n type compounds, And TiO2 material has low working temperature, excellent performance, simple preparation technology, non-toxic, the advantages of low cost, abundant resources, so the TiO2 materials are widely used. The method of doping other metal oxide improve TiO2 response time of gas sensitive material, reducing the working temperature of TiO2 gas sensitive material, improving the sensitivity of TiO2 gas sensitive material, and thus enhanced the gas-sensing properties of TiO2 materials. This article by sol-gel method make SnO2-TiO2 thick film and its research, exploring the TiO2 gas-sensing properties and preparing technology conditions, by the relationship between through multiple sets of experiments to determine the best preparation program.By sol-gel method with butyl titanate and stannic chloride as precursor system for Ti(OH)4 colloid, after drying, presintering, cleaning, SnO2-doped TiO2 thick film are obtained. By XRD, SEM and the analysis of the gas sensor test system the TiO2 thick film crystal structure, surface morphology and gas sensitive performance. Determining the factors such as pH, stirring speed, water content of Ti(OH)4 the influence degree of the colloid. Studying the doping amount, annealing temperature, all kinds of gases and the gas concentration on the properties of SnO2-TiO2 thick film gas sensor.The conclusion is shown that:1. The H2O: Ti(OC4H9)4: CH3CH2 OH = 1:3:12, moderate reaction rate, the formation of colloid stability and uniform;2. Adjusting the solution pH to 2-3, and stirring speed of 80 r/min, the slowly drip into the speed can be sol viscosity moderate, form a stable gel evenly;3. After 700 ℃annealing at% 4 doped SnO2-TiO2 material prepared of gas sensitive element, has a good selectivity to ethanol gases, and 60 PPM for ethanol concentration, the sensitivity of gas sensitive element: 26;4. At working temperature 63℃, the sensitivity of gas sensitive element for ethanol gas can reach 1903, response time and recovery time : 1s, 3s respectively. The preparation of the gas sensor can be used in the practical application of ethanol gas detection;5. Through the theory of gas molecular orbital energy level, Calculation of ethanol, methanol, acetone, formaldehyde gas molecular orbit HOMO and LUMO energy, further explaining the gas-sensing properties.