The Preparation And Gas Sensing Performance Of Mesoporous SnO₂-based Thin Films

Mesoporous material has the pore diameter between2nm and50nm and high specificarea, which is beneficial to the increasing of gas absorbing. So it has important applicationpotential in the field of gas sensing materials. This paper prepared the pure and dopedSnO2thin films with polyethylene glycol2000(PEG2000) as the template, which wasremoved by calcination. Firstly, we studied the impact of different experimentalparameters on the structure and performance of thin films. Then, we studied the impact ofCuO and Ag doping on the structure and performance of thin films. The mainexperimental results were as follows:(1) The mesoporous structure of SnO2thin films was influenced by manyexperimental parameters. The thin film had the best structure and performance with theSn4+concentration being0.2mol/L. If the concentration decreased, the thin film continuitydropped, while the thin film became denser with Sn4+concentration increasing. When thequantity of PEG2000increased from0.30g to0.50g, the thin film continuity dropped. Thethin film continuity rised a little and the diameter decreased with the quantity increasedfrom0.50g to0.90g. With the volume of deionized water increasing, the thin filmcontinuity and the diameter increased, the sensitivity of thin films to ethanol dropping.PEG2000had complete decomposition gradually with the calcination temperatureincreasing. But the incomplete decomposition of the template may be good to theabsorption of alcohol, leading the sensitivity of thin films to improve;(2) The morphology and performance of thin films changed after doping CuO. Whenmolar doping ratio of CuO was1%, the sensitivity of thin films to both ethanol andmethanol was improved at relatively low heating voltage. While the doping quantity keptincreasing, the formation of SnO2mesoporous structure was affected, leading thesensitivity of thin films to ethanol and methanol to drop;(3) The sensitivity of thin films was improved after doping Ag. The film had gassensing performance improved after doping Ag, which was prepared with calcinationtemperature being500℃for3hours. Another sample was prepared with calcination temperature being500℃for2hours and was dipped in AgNO3solution with the sameconcentration. It was sensitive to ethanol at relatively low heating temperature and itssensitivity almost increased linearly with the concentration increasing.