【作者】 张媛媛；

【导师】 陈烨；

【作者基本信息】 东华大学 ， 材料物理与化学， 2022， 硕士

【摘要】 工农业生产、汽车尾气排放会产生大量的氨气（NH₃）,它作为一种有毒的刺激性气体,长期处于高于25 ppm的NH₃气氛中会对人体的呼吸系统、皮肤、眼睛等造成损伤;此外,氨气存在于人体呼出气体中,是一种重要的生理指标。随着气体传感器和柔性电子器件的不断发展,研究者们将目光转向了可在室温下对待测气体进行实时检测的柔性气体传感器。SnO₂因其对多种气体的高灵敏度响应,是气体传感材料的重要组成部分。为降低SnO₂的工作温度,学者们从减小晶粒尺寸、设计低维纳米结构、设计SnO₂复合传感材料等方面展开了研究。还原氧化石墨烯（rGO）具有优异的电导率和化学稳定性,将其与SnO₂复合,可以极大地减小传感器的电阻,能一定程度上改善气体传感性能,并实现室温下的气体检测。目前,柔性气体传感器的制备一般是将预制备的传感材料以物理吸附的方式沉积在柔性基材表面成膜,在使用过程容易发生磨损和脱落。本文提出了一种新型的柔性气体传感器制备方法,借助Sn⁴⁺和GO间的静电吸引力,以层层自组装的方式在预处理过的聚酰亚胺织物表面形成稳定的多层膜,然后采用水热法使Sn⁴⁺和GO在织物表面原位成核和还原得到SnO₂/rGO复合涂层织物,以期得到均匀分散的小粒径SnO₂,并增强SnO₂和rGO的相互作用以及涂层的牢固度。论文主要内容和结论如下:（1）采用静电层层自组装的方式在预处理的聚酰亚胺（PI）织物表面涂覆Sn⁴⁺和GO,并通过原位水热法在织物表面原位生长得到SnO₂/rGO复合涂层。通过拉曼光谱、扫描电镜、X射线衍射仪和静态气体测试系统表征了不同实验条件下样品的形貌结构、导电性能和氨气传感性能。结果表明:Sn⁴⁺/GO浓度比为100(m M/mg·mL^-1)时,将Sn⁴⁺和GO在PI表面循环涂覆5次,于180℃的水热釜中反应16h,制得的PI-SnO₂/rGO在室温下对200 ppm氨气的灵敏度最高。复合涂层中SnO₂纳米粒子分散均匀,粒径约为3 nm。随着初始GO羧基化程度的下降,SnO₂纳米粒子粒径稍有增大,SnO₂ NPs和rGO的相互作用减弱。（2）室温下测试最佳工艺条件下制备的复合涂层织物的氨气传感性能,PI-SnO₂/rGO表现为n型传感,对100 ppm NH₃的响应值为5.16%,具有较快的响应速度（94 s/57 s）;传感器对50～400 ppm NH₃的检测表现出良好的线性响应（R²=0.995）;传感器对氨气的响应值也高于干扰行气体,选择性好;器件表现出良好的连续测量重复性和长期稳定性;织物传感器在不同湿度条件下（42%～65%）灵敏度变化率<5%,具有较好的稳定性;通过显微拉伸仪对复合涂层织物拉伸2000次后,灵敏度损耗仅为3%,表现出优异的耐机械变形性。随着初始GO羧基化程度对下降,PI-SnO₂/rGO*则表现为p型传感,对100 ppm NH₃的响应值为11.3%,响应和恢复时间较长（1000 s/267 s）,这主要归结于NH₃分子作用位点的改变,NH₃由SnO₂表面转为与rGO片层表面接触,且SnO₂和rGO的电荷传输作用减弱。本文提供了一种新型织物基气体传感器的制备方法,简单可控,传感器表现出良好的稳定性,可在柔性气体传感器和可穿戴电子器件等领域中推广这一方法。更多还原

【Abstract】 Industrial and agricultural production and automobile exhaust emissions produce large amounts of NH₃,which,as a toxic and irritating gas,can cause damage to the human respiratory system,skin,and eyes when exposed to NH₃ atmosphere over 25 ppm for a long time;in addition,ammonia is present in human exhaled gas and is an important physiological indicator.With the continuous development of gas sensors and flexible electronic devices,researchers have turned their attention to flexible gas sensors that can detect the gases to be measured in real time at room temperature.SnO₂ is an important component of gas sensing materials due to its high sensitivity response to a variety of gases.To reduce the operating temperature of SnO₂,scholars have conducted research in reducing the grain size,designing low-dimensional nanostructures,and designing SnO₂composite sensing materials.Reduced graphene oxide（rGO）has excellent electrical conductivity and chemical stability,and its composite with SnO₂ can greatly reduce the resistance of the sensor,which can improve the gas sensing performance to a certain extent and realize gas detection at room temperature.Currently,flexible gas sensors are generally prepared by depositing the pre-prepared sensing material on the surface of the flexible substrate in the form of physical adsorption to form a film,which is prone to wear and peeling in the process of use.In this paper,we propose a novel method for the preparation of flexible gas sensors,in which a stable multilayer film is formed on the surface of pretreated polyimide fabric by layer self-assembly with the help of electrostatic attraction between Sn⁴⁺and GO,and then a hydrothermal method is used to nucleate and reduce Sn⁴⁺and GO in situ on the fabric surface to obtain a SnO₂/rGO composite coated fabric,in order to obtain uniformly dispersed small particle size SnO₂（3 nm）,and enhance the interaction between SnO₂ and rGO as well as the solidity of the coating.The main contents and conclusions of the paper are as follows.（1）Sn⁴⁺and GO were coated on the surface of pretreated polyimide（PI）fabric by electrostatic layer-by-layer self-assembly,and the SnO₂/rGO composite coating was obtained by in situ hydrothermal growth on the fabric surface.The morphological structure,electrical conductivity and ammonia sensing properties of the samples under different experimental conditions were characterized by Raman spectroscopy,scanning electron microscopy,X-ray diffractometer and static gas testing system.The results showed that the PI-SnO₂/rGO produced at a Sn⁴⁺/GO concentration ratio of 100(m M/mg·m L^-1)had the highest sensitivity to 200 ppm ammonia gas at room temperature by cyclically coating Sn⁴⁺and GO on the PI surface five times and reacting in a hydrothermal kettle at 180°C for 16 h.The SnO₂ nanoparticles in the composite coating were uniformly dispersed with a particle size of about 3 nm.As the initial GO oxidation decreased,then the SnO₂ nanoparticle particle size increased slightly and the interaction between SnO₂ NPs and rGO weakened.（2）The ammonia sensing performance of the composite coated fabric prepared by optimal process conditions was tested at room temperature.PI-SnO₂/rGO exhibited n-type sensing with a fast response value of 5.16%for 100 ppm NH₃（94 s/57 s）;the sensor showed a good linear response（R²=0.995）for the detection of 50-400 ppm NH₃.The response value of the sensor for ammonia is also higher than that of the interfering line gas,with good selectivity;the device shows good continuous measurement repeatability and long-term stability;the fabric sensor has good stability with a sensitivity change rate of less than 5%under different humidity conditions（42%～65%）;the sensitivity loss is only 3%after 2000 times of stretching of the composite coated fabric by the micro tensionmeter,showing excellent resistance to mechanical deformation resistance.As the initial GO oxidation level decreases,PI-SnO₂/rGO*shows p-type sensing,with a response value of 11.3%for100 ppm NH₃ and a long response and recovery time（1000 s/267 s）,which is mainly attributed to the change of the NH₃ molecular action site,with NH₃ shifting from the SnO₂ surface to contact with the rGO sheets surface,and a weakened charge transfer between SnO₂ and rGO.The charge transfer between SnO₂ and rGO is weakened.The essay provides a new fabric-based gas sensor preparation method,which is simple and controllable,and the sensor exhibits good stability,and this method can be promoted in the fields of flexible gas sensors and wearable electronic devices.更多还原