Influence of Doping Methods on the Gas-sensing Properties of CuO-SnO_2 Sensors

摘要

Nano crystalline SnO_2 was prepared by sol-gel with PEG surfactant. CuO was doped in the SnO_2 by mechanical mixture and reaction congelation from CuCl. The samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and nitrogen adsorption isotherms (BET). The results indicated that the average crystal size of SnO_2 at sintering temperature of 550 °C was 10 nm, the conglomeration size of SnO_2 was about 100 nm. The specific surface area of pure SnO_2, mechanical doping SnO_2 and reaction doping SnO_2 were 110, 84, 72 m~2/g, respectively. The thick film gas sensors made from these samples were examined. SnO_2 doped by different methods had different electrical and gas-sensing properties. The sensors based on CuO doped SnO_2 films exhibited iess sensitive to ethanol gas but extremely higher sensitivity to H_2S gas than that of pure SnO_2.