【作者】 夏晓东；

【导师】 俞汝勤；

【作者基本信息】 湖南大学 ， 分析化学， 2005， 硕士

【摘要】 本论文研究了金属氧化物半导体纳米材料NO₂气体传感器,主要包括四部分的工作:⑴采用溶胶-凝胶法合成了In₂O₃纳米晶,首次研究了SiO₂掺杂的In₂O₃纳米晶对NO₂气体的气敏特性。所制作的气体传感器对空气中的NO₂有良好的响应。材料的合成方法简单,通过掺杂SiO₂改善了传感器对NO₂气体的气敏性能,提高了灵敏度,缩短了响应时间。⑵采用分解白钨酸法制得WO₃纳米粉体,用固相反应法掺杂SiO₂,研制了一种SiO₂掺杂的WO₃半导体NO₂气体传感器,制作方法简便,对NO₂气体具有良好的响应,是一种有实际应用前景的气体传感器。这种NO₂气体传感器的特点是稳定性好。⑶金属氧化物半导体材料的气敏特性与材料的制备过程有关,材料的制备条件,决定了气敏材料的微观结构、晶相组成以及元素的电子状态,因而影响其气敏性能。采用不同于分解白钨酸的方法制备了WO₃纳米材料半导体。先由Na2WO4溶液通过离子交换法制备钨酸,再选择不同的制备条件,制备了具有不同性能的WO₃纳米材料。用这些WO₃纳米材料制作的NO₂气体传感器其气敏特性也不相同。实验表明可通过控制气敏材料的制备条件来改善气敏材料的气敏性能。⑷复合氧化物半导体材料发展最迅速,是气敏材料的开发重点。探索了用较为简便的方法分别合成WO₃、SnO₂和TiO₂纳米粉体,并利用前文所合成的In₂O₃纳米晶,通过固相反应掺杂法,得到了相应的WO₃基复合氧化物纳米材料。用这些复合纳米材料制作的气敏器件,增强了对NO₂气体的气敏特性。大气污染已引起世界各国的关注,来源于内燃机和汽车尾气的含氮氧化物是严重的大气污染物之一,利用气体传感器对其进行快速在位、实时检测具有重要意义。纳米科技的发展为研制这种高性能的气体传感器提供了可能。本论文制作的气体传感器为陶瓷烧结体气敏器件。这类基于金属氧化物半导体纳米材料的NO₂气体传感器,其响应信号与NO₂气体浓度在一定区间内具有线性关系。各传感器对NO₂气体的响应灵敏度高、快速、可逆、选择性好。更多还原

【Abstract】 This dissertation focuses on the NO₂ gas sensors fabricated using metal oxide semiconductive nanomaterials as sensing materials, mainly including four parts: Firstly, solid-state Taguchi-type NO₂ gas sensors were fabricated with pure In2O₃ and SiO₂-doped crystalline In2O₃ synthesized by sol-gel method. The sensing characteristics, such as response time, response linearity, sensitivity, working temperature, and working range were studied in detail. Sensors prepared with these sensing nanomaterials show good sensing characteristics to NO₂ gas, and SiO₂-doping improves sensitivity. Response and recovery are rapid. Secondly, Thin film NO₂ sensors were fabricated using pure WO₃ and SiO₂-doped WO₃ nanoparticles with various SiO₂ contents （0-10%, wt%）. WO₃ nanoparticles were obtained by the means of thermal pyrolysis of white tungstic acid starting from Na2WO₃ then followed with ultrasonic treatment, and SiO₂ powder was synthesized via the sol-gel route. SiO₂-doped WO₃ nanoparticles were synthesized by solid-state reaction under the proper temperature. The NO₂ responses were found to be very high and quite reversible, while the response and recovery times were fast and the reproducibility was satisfactory. The sensors show good long-term stability during 110 days. Thirdly, NO₂ gas sensors were fabricated with pure WO₃ powder obtained under different calcinating temperature from tungstic acid which in turn was prepared by passing an aqueous Na2WO4 solution through a cation exchange resin protonated in advance. Various types of WO₃ powder show different sensing characteristics, such as the sensitivity and the best working temperature range. The experimental results show the possibility of improving the NO₂ gas sensor’s characteristics through controlling the synthesis parameters. Lastly, the metal oxide composites semiconductor NO₂ sensing materials were prepared and examined, including SnO₂-WO₃, TiO₂-WO₃ and In2O₃-WO₃ by the use of solid-state doping reactions. The sensing characteristics of the WO₃-based composites improved greatly compared with the former sensors. The environmental protection policies of most countries are oriented towards the regulation of measurement and control of toxic gases in the atmosphere. Nitrogen oxides （NOx: NO₂ and NO） are typical toxic gases released from combustion facilities and automobiles. The on-site and real-time detection of hazardous gas calls for gas sensors with low energy consumption, fast response, and rapid recovery. The advent of nanostructured materials with enhanced properties paved the way to improve the gas detection. Thus, the fabrication of gas sensors using novel nanomaterials has recently been an active topic. This paper presents the results obtained with metal oxides gas sensors showing sensitivity to NO2 in the parts per million （ppm） range. These metal oxide semiconductor, Taguchi-type NO2 gas sensors prepared with the obtained nanomaterials as sensing materials show the fastest response and recovery time, good linearity, low resistance, low working temperature, high sensitivity, and good long-term stability.更多还原