碳纳米管掺杂纳米ZnO气敏元件敏感特性

SENSING PROPERTIES OF NANO ZnO GAS SENSOR DOPED WITH CARBON NANOTUBE

采用溶胶–凝胶法合成纳米ZnO,以碳纳米管(carbonnanotube,CNT)为掺杂剂制备CNT–ZnO旁热式气敏元件样品。用X射线衍射和透射电镜分析了ZnO的结构,用扫描电镜观察CNT–ZnO气敏元件样品表面的显微形貌,研究了CNT–ZnO元件对甲醛和丙酮等气体的气敏性能。结果表明:CNT存在于平均粒径为20～30nm的ZnO晶粒间,增加了CNT–ZnO材料的气孔率。CNT–ZnO气敏元件对丙酮的灵敏度高于纯ZnO元件,掺0.6%(质量分数)CNT的ZnO气敏元件(0.6%CNT–ZnO)气敏元件对质量分数为40×10–6甲醛有最高灵敏度(15.11)。而且具有能检测低浓度甲醛气体、选择性好,响应速度快(响应时间约为15s)的优点。

The nano-sized ZnO powder was prepared by the sol–gel method. The heater-type gas sensor was prepared by doping car-bon nanotube （CNT） in ZnO powder. The structure of ZnO was characterized by X-ray diffraction and transmission electron micros-copy. The morphology of the CNT–ZnO gas sensor was observed by scanning electron microscopy. The gas sensing properties of CNT–ZnO sensor were investigated. The results show that CNT exists among ZnO grains with an average particle size about 20–30 nm, which increases the porosity of CNT–ZnO materials. The CNT–ZnO gas sensor is more sensitive to formaldehyde than pure ZnO sensor. The CNT–ZnO sensor doped with 0.6% in mass of CNT has the highest sensitivity （15.11） to the formaldehyde at 40 × 10–6 in mass. It also has advantages of detecting formaldehyde with low concentration gas, high selectivity and short response time which is only 15 s.