| As the development of industry, more poisonous, harmful gases were produced. Therefore, it has been one of the hottest subjects to study on gas sensors.SnO2is one of the earliest semiconductor gas sensors which were used in daily life. At present, research on SnO2gas sensor is focused on doping additives, altering the micro and macrostructure of the oxides. All these are to enhance sensor’s sensing property. In recent years, more and more rare earth oxides became to be used as special materials because of their good surface modification and catalytic effect.Tin oxide thin film in this work was prepared on the surface of glass (ITO) by electrodeposition, doping with a small amount of La2O3. The La2O3/SnO2sensing material was characterized by SEM and XRD. The film is homogeneous and porous with crystal size. To prepare the film, we studied on the effect of current size, electroplating and sintering time, and so on. The optimized conditions of preparing thin film are as follows. Tin was deposited in the solution of SnCl2, with a concentration of7.0g·L-1. Current intensity was kept as1mA for3600s. Then the glass was dipped in another solution of LaCl3, with a concentration of19.0g·L-1. At last, the product was sintered at600℃in air for8h.We assembled a sensor and detected its properties by the DC resistance method. The ethanol concentration ranges from50to500ppm, and the temperature is from250to400degree. The results showed that the response sensitivity is in the range of21.1to50.4, much higher than those reported in the literature.This kind of gas sensor has good sensitivity and selectivity to ethanol gas, compared with other reducing gases such as H2S, H2, NH3, CH3COCH3. We did lots of repeated experiments, which could prove the sensor’s good reproducibility. The response mechanism of La2O3/SnO2for ethanol gas was also discussed in present paper. |
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