【作者】 王涛；

【导师】 肖奇；

【作者基本信息】 中南大学 ， 材料科学与工程， 2014， 硕士

【摘要】 CuO作为一种重要的p型半导体,由于具有优异的表面电导率近年来已经在气体传感器领域引起大量的关注。然而,与常用的n型半导体材料(如Sn02和ZnO)相比,p型的CuO对测试气体的灵敏度通常较低。尽管ZnO已长期用于气体传感器领域,但该材料由于灵敏度低、选择性差和工作温度高的缺点在一定程度上限制了它的实际应用。离子掺杂和形貌控制被认作是提升气敏性能的两种有前途的方法。本论文通过形貌控制的方法提升了介孔-大孔CuO微球对乙醇的灵敏度,以Co和Fe元素对介孔ZnO微球进行掺杂分别提升了其对乙醇和正丁醇的灵敏度。论文主要结果如下：(1)采用溶剂热法制备了由纳米片组装的介孔-大孔CuO微球,其比表面积为42.0m2/g、孔孔容为0.224cm3/g,孔径主要分布在8-58nm之间,且片状构筑单元的厚度约为50nm。该样品在150℃的工作温度下对100ppm乙醇的灵敏度为13.7。灵敏度的提升是由比表面积和孔容的增大及片状构筑单元厚度的减小引起的。(2)采用水热法制备了Co掺杂的介孔ZnO微球。摩尔比为3%的Co掺杂ZnO样品的比表面积为59.5m2/g、孔容为0.110cm3/g、孔径主要分布在2-12nm之间。钴离子在样品中以+2价存在并且取代了ZnO晶格中Zn2+的位点。该掺杂量的ZnO元件具有最高的灵敏度,在350℃工作温度下对100ppm乙醇的灵敏度达78.1,此数值是纯ZnO元件的5倍以上。该元件对100ppm乙醇的恢复时间为9s。在90天内,该元件对乙醇灵敏度波动的最大偏差不超过10%。灵敏度的提升归结于更高的施主缺陷含量及更大的比表面积。(3)采用水热法制备了Fe掺杂的介孔ZnO微球。摩尔比为4%的Fe掺杂ZnO样品的比表面积为56.2m2/g,孔容为0.125cm3/g,孔径主要分布在5-33nm之间。Fe掺杂的ZnO元件能探测ppb级的正丁醇。摩尔比为4%的Fe掺杂ZnO元件在300℃工作温度下对正丁醇具有最佳的灵敏度。它对100ppm正丁醇的灵敏度高达230.4,此数值是纯ZnO元件的11.5倍。该元件对10ppb正丁醇的灵敏度为1.6,对正丁醇的检测下限小于10ppb,且对正丁醇具有好的选择性。灵敏度的提升归结于更高的施主缺陷含量及更大的比表面积。更多还原

【Abstract】 As an important p-type semiconductor, CuO has been recently attracted a great deal of attention for gas sensor applications due to the well-known surface conductivity of CuO. However, p-type CuO usually has lower responses to analytical gases than frequently-used n-type semiconductor materials, such as SnO2and ZnO. Although the utilization of ZnO in the field of sensing gases has a long history, it has been, somewhat limited in the real applications, due to low sensitivity, poor selectivity and high working temperature. Ions doping and morphology control are regarded as two promising strategies to improve the gas-sensing properties. The responses to meso-macroporous CuO microspheres towards ethanol were improved by the way of morphology control in this paper. And the responses to mesoporous ZnO microspheres towards ethanol and n-butanol were improved with Co and Fe as dopants, respectively. The main contexts are as follows:(1) The meso-macroporous CuO microspheres composed of nanosheets were prepared by the solvothermal method. CuO microspheres had a specific surface area of42.0m2/g, a pore volume of0.224cm3/g, and a main pore size of8-58nm, as well as the platelet-like building blocks had a thickness of about50nm. The response of CuO microspheres to100ppm ethanol was13.7at a working temperature of150℃. The enhancement of the response was attributed to the larger specific surface area、the larger pore volume and thinner platelet-like building blocks.(2) Co-doped Mesoporous ZnO microspheres were prepared by the hydrothermal method. The3mol%Co-doped ZnO sample had a specific surface area of59.5m2/g, a pore volume of0.110cm3/g, and a main pore size of2-12nm. Co species existed as a form of divalent state in the sample and substituted Zn2+sites in ZnO crystal lattice. The sensor showed the highest response value of78.1to100ppm ethanol at350℃, which were5folds higher than that of the pure ZnO sensor. The recovery time of the3mol%Co-doped ZnO sensor to100ppm ethanol was9s. The maximal deviations of the responses to ethanol are less than10%in 90days. The improvement of the response was contributed to higher donor defects contents combined with larger specific surface area.(3) Fe-doped Mesoporous ZnO microspheres were prepared by the hydrothermal method. The4mol%Fe-doped ZnO sample had a specific surface area of56.2m/g, a pore volume of0.125cm/g, and a main pore size of5-33nm. Fe-doped ZnO sensors could detect n-butanol down to ppb level. The4mol%Fe-doped ZnO sensor showed the best response to ppb-level n-butanol at300℃. The sensor had a response value of230.4to100ppm n-butanol, which was11.5folds as high as that of the pure ZnO sensor. The sensor had a response value of1.6to10ppb n-butanol with a detection limit of n-butanol below10ppb.And the sensor exhibited good selectivity to n-butanol. The improvement of the response was contributed to higher donor defects contents combined with larger specific surface area.更多还原