面向大气环境中低浓度NO2检测的石墨烯复合材料基气体传感器阵列研究

In this project, we plan to manufacture high performance gas sensor arrays with high sensitivity, high selective, high reliability and fast response to low concentration of NO2 at room temperature. For this purpose, the sensing materials and device structures are designed and optimized. We plan to synthesize the graphene/metal oxide semiconductor composites and study their gas sensing applications. Graphene has many advantages such as large specific area, high electron mobility and the metal oxide semiconductor nanoparticles are excellent materials for gas sensing with high identification ability. Thus, the graphene/metal oxide semiconductor composites mentioned in this project will integrate the advantages of both graphene and metal oxide semiconductor nanoparticles and have some unique sensing properties. The composites will be used as gas and humidity sensing materials to build high performance gas sensor arrays. The gas sensor arrays are composed of two parts, a NO2 detecting unit and a precise humidity compensating unit. Utilizing the first-principles, composite materials are theoretically analyzed and designed. This also helps us to get a brief insight into the relationship between the composition, structure and sensing properties. We will adopt one-step hydrothermal method to synthesize the composite sensitive materials. The optimal synthesis condition will also be found out to realize the controlled preparation for the composite materials. We will discuss the relationship between composition, structure, morphology and sensing properties, and investigate the mechanism of synergy enhancement effect, so that we can establish proper methods to synthesize composite materials. Then, we will investigate the influence of the electrode’s composition and structure on the device performances and establish a suitable method to prepare electrodes. Our ultimate aim is to develop the high performance gas sensors which are suitable for trace detection of NO2 at room temperature with the detection limit of 10 ppb. The implementation of this project will not only benefit the establishment of the strategies to design and synthesize high performance gas sensing materials and devices, but also may develop practical high performance environment gas sensors with potential application prospect.

本项目从敏感材料及器件结构两方面入手，对传感器进行设计与优化，从而在室温条件下实现对大气环境中低浓度NO2的高灵敏度、高选择性、高可靠性的快速检测。设计并制备石墨烯/半导体氧化物复合材料，将石墨烯比表面积大、电子迁移率高等特点与半导体氧化物材料的识别能力强的优势相融合，利用协同增感效应，引入高精度湿度补偿单元，构建高性能气体传感器阵列。通过第一性原理，从理论上对材料进行初步设计；利用一步水热法制备复合材料，优化制备条件，实现材料的可控制备；研究材料的组成及微观结构与其气体或湿度敏感特性的关系，明晰增感机制；设计平面型结构器件，研究器件电极材料的组成与结构对器件性能的影响，确立电极制作的工艺条件；最终研制出可室温工作，具有良好抗湿性能，检测下限可达到10 ppb的高性能NO2传感器阵列。该项目的实施，不仅可确立复合材料与器件的设计及制备策略，还有望开发出具有潜在应用前景的高性能环境气体传感器

NO2是大气环境的重要污染物之一，开发在低温工作的，可以对低浓度NO2进行快速检测的传感器已经成为摆在人们面前的重要任务。目前，气体传感器的设计主要集中在两个方面：一是传感器结构的设计，二是对传感器敏感材料的设计。本项目的主要研究内容为设计、制备和表征石墨烯/半导体氧化物复合材料；研究石墨烯/半导体氧化物复合材料的组成和微观结构与敏感特性的关系；通过对敏感材料和电极结构的合理设计及选择，制备低功耗、高灵敏、高选择、响应恢复迅速的低浓度NO2传感器。.取得的主要成果包括：1. 通过简单的水热和随后的热处理方法合成了由纳米片组成的WO3空心球，研究了pH值对材料的形貌和气敏特性的影响。基于WO3空心球的传感器在室温下对NO2具有良好的敏感特性。传感器对300 ppb NO2的响应为15.1，相应的响应和恢复时间分别为670和2940 s。当NO2低至50 ppb时，传感器的响应可以达到1.5。传感器还具有良好的选择性和可重复性。2. 通过简单的溶剂热和随后的热处理方法合成了具有独特花状结构的In2O3材料；探索了溶剂热反应时间对材料的影响。制造并测试了一系列气体传感器，发现反应时间为20 h的材料制备的NO2传感器，除具有较低的工作温度和检测限外，还有良好的选择性，重复性和长期稳定性。它的最佳工作温度低至100°C，对1 ppm NO2的响应为63.6，相应的响应和恢复时间分别为344和318 s。传感器的检测下限可以达到50 ppb。3. 采用简单的一步微波水热法制备了SnO2/rGO复合材料。材料的气敏特性测试表明，在75℃时，复合材料对350 ppb NO2的响应是纯SnO2的6.6倍。此外，响应时间和恢复时间从39.2/54.7分钟缩短到6.5/1分钟，检测限低至50 ppb。本项目所获研究成果为半导体氧化物材料及石墨烯/半导体氧化物复合材料的可控制备提供了一定的借鉴，为复合材料增敏机理提供了一定的解释，最终为面向低浓度NO2检测的低功耗气体传感器设计及制备提供了参考，具有一定的理论价值和潜在的应用可能。