同轴异质结构柔性纳米纤维氨气传感器的构建及其氨敏机理研究

Gas sensor is a device that can transfer the volume fraction information of a specific gas into electrical signals, and high responses, repeatability and selectivity are required. Ammonia often comes from nature or emitted by industrial manufacture and so on, and high concentration ammonia is harmful to health and safety, therefore, it is of great significance to detect them accurately. The performance of gas sensor is closely related to the surface area and interface structure of its gas sensing materials. With larger specific surface area, the number of contact points between the materials and the target gas will be increased, and the heterostructure at the interface can play the role of signal amplification in the process of gas sensing. Currently, inorganic semi-conductor ammonia sensors have been widely used. However, three-dimensional structures can hardly be maintained due to the rigidity of inorganic materials, thus leading to impaired sensing properties. In applicant's previous research, it was found that the prepared flexible nanofibers with CuO, TiO2 and polyaniline as main components maintained three-dimensional structure and the ammonia sensing properties were improved obviously, which were related to the heterostructure at the interfaces between the components. But the structure-property relationship and impact factors on the formation of flexible nanofibers are not very clear. Aiming at solving the problems above, the applicant plan to improve the effectiveness of heterostructures by designing and regulating the spatial position of each component, and clarify the gas sensing mechanisms. This project will provide some theoretic reference for the development of new gas sensors with good ammonia sensing properties.

气体传感器是一种将某种气体体积分数转化成电信号的装置，要求其具有高灵敏度、重复性和选择性等。氨气常来自自然界和工业生产等领域，过高浓度对健康和安全有较大危害，因此对其准确检测具有重要意义。氨气传感器的性能与其比表面积及界面结构有密切关系，较大比表面积可增加材料与目标气体的接触位点，界面异质结构在材料气敏过程中可起到信号放大的作用。目前无机半导体氨气传感器应用广泛，但由于其刚性难以保持三维立体形貌而影响其氨敏性能。申请人前期研究发现，以CuO、TiO2和聚苯胺为主要成分制备的无机/有机半导体柔性纳米纤维具有三维立体结构，氨敏性能有较大提高，这与各组分间界面处的异质结构有关，但目前其构效关系和柔性化影响因素还不清楚。本课题以解决上述问题为目标，通过设计和调控各组分的空间位置，提高异质结构有效性，阐明氨敏机理，为开发氨敏性能良好的新型气体传感器提供理论依据。

气体传感器是一种将某种气体体积分数转化成电信号的装置，要求其具有高灵敏度、重复性和选择性等。气体传感器的性能与其比表面积及界面结构有密切关系。本项目以探究无机-有机半导体异质结、金属-有机半导体复合纳米纤维气敏材料，探究异质结构和电子的迁移速率在气敏过程中的构效关系和响应机理等；同时拓展研究了下转换及导电材料性能为优化本项目核心内容-氨敏材料性能提供指导。主要内容如下：.（1）以纤维素纸为模板，原位聚合的方法成功制备了PANI/纤维纸复合材料，用SEM、FTIR对材料进行表征，并用气敏传感测试系统进行对比分析，选择出气敏性能最佳的苯胺浓度；进一步的，在纤维纸表面沉积TiO2，研究PANI@TiO2/纤维纸复合材料中异质结构对材料气敏性能的影响，阐明性能提高的机理。.（2）以柔性SiO2纳米纤维为模板，利用静电纺丝结合静电喷雾、高温煅烧以及原位聚合的方法将N型半导体材料CeO2与PANI复合，探究CeO2对基于PANI的复合气敏材料性能的影响。探究其对复合材料气敏性能的影响机理。结果显示，材料最低可以检测到400ppb的氨气。.（3）以静电纺PAN纳米纤维为模板，通过原位聚合和光辅助的方法将金属银与PANI复合，探究金属银对PANI基气敏复合材料性能的影响。探究银单质在复合气敏材料对氨气的检测过程中电子的迁移速率等的影响。结果显示，材料对100 ppm的氨气的响应值可达15.0。.（4）利用微波固相合成结合高温煅烧技术制备了四钛酸钾晶须，研究了微波煅烧温度晶须成型的影响，并以此为模板，通过K+/H+离子交换制备了具有大长径比的TiO2晶须，并研究了微波煅烧参数对TiO2晶须晶型转变的影响。结果显示，晶须长度可达11.85um，晶须的电阻率为1.002kΩ，Hunter白度为83.4。.（5）采用高温固相法制备绿光色长余辉发光SrAl2O4: Eu2+, Dy3+和蓝光色长余辉发光材料Sr2MgSi2O7:Eu2+, Dy3+；同时掺入偶联剂和光转换剂，用非均相沉淀法制备一种下转换SrAl2O4: Eu2+, Dy3+/Sr2MgSi2O7:Eu2+, Dy3+/光转换剂红光发光材料，并对其性能进行了研究。