Zn^(2+)掺杂WO_3基气敏材料的制备及气敏性能研究

Preparation and Gas Sensing Properties of WO_3-Based Gas Sensors by Doping Zn^(2+)

通过加热分解钨酸制备的WO3与Zn(NO3)2溶液超声分散,制备出了掺杂Zn2+的WO3基气敏材料。研究了Zn2+掺杂对WO3气敏材料性能的影响。结果发现,Zn2+掺杂WO3基传感器对H2S有较好的气敏性能,在常温下对极低浓度(5×10-6)H2S也有很高的灵敏度(56),适量掺杂可以提高其灵敏度,Zn2+掺杂n_Zn^(2+)/n_W=2%的WO3基传感器的灵敏度最大,对50×10-6H2S在200℃灵敏度可达1800。通过X-射线衍射仪(XRD),比表面测定仪(BET)对材料进行了表征,比表面积范围介于2.5～3.5m2/g之间。结合有关理论,对元件气敏现象及机理进行了解释。

The WO3 powder was obtained by means of thermal pyrolysis of tungstic acid, then an appropriate amount of powder was impregnated into the solution of Zn（NO3）2 with ultrasonic treatment to prepare the WO3 composite of various mole ratio of Zn^2＋ （0 at%, 1 at%, 2 at%, 5 at%, 7 at%, 10 at%）. The gas sensing performances to ethanol, acetone, xylene, formaldehyde and H2S were studied for the as-synthesized samples. Particularly, the gas-sensing performance to He S was investigated in detail at different temperatures and concentrations. The results show that the Zn^2＋ doped WO3-based gas sensors have high sensitivity even to a very low concentration （5 × 10^-6） of H2S at room temperature and appropriate amount of Zn^2＋ doping can significantly improve its gas sensing properties. The WO3-based gas sensor by doping 2 at Zn^2＋ shows a maximum sensitivity of 1 800 towards 50×10^-6 H2S at 200℃. The samples were characterized by X-ray diffraction（XRD） and BET method. The specific surface areas of the samples were all in the range of 2. 5-3. 2 m^2/g. At last, the phenomena and gas-sensing mechanism of these sensors were also discussed.