多糖/金属氧化物/碳纳米管杂化材料的可控制备及气敏性研究

Carbon nanotubes are promising for gas sensor application due to their unique properties, such as high surface area and good electrical conductivity. The surface modification is an effective way to improve the sensing properties of carbon nanotubes, and metal oxides are the typical modification materials which can integrate their unique properties of both components and make the sensor with low operation temperature, high sensitivity and fast response. However, the size effect of metal oxides and the selectivity are still the challenges of metal oxide/carbon nanotube hybrid sensors. . The objective of this proposal is to establish the structure-property relationship between the modification materials parameters and the resulting sensing responses. The integration of synthesis, characterization, and modeling is the critical component of the proposal which will allow optimization of synthesis conditions in order to obtain materials with the desired sensing properties. By controlling the thickness of oxide with sputtering and then comparing the results of sensing experiment, the relationship among the maximum response, the thickness of metal oxide, and the properties of metal oxides are going to be established. Then, polysaccharide is used to further modify the surface, and the related factors, such as thickness, mass ratio of components, will be carefully investigated. Finally, an interaction mechanism is going to be given through the investigation of material interface.. The scientific impact is associated with the furthering of the fundamental understanding of principles underpinning the fabrication techniques towards high performance, interaction of gases and chemicals at surfaces, and surface modification effects on sensitivity of carbon nanotube.

碳纳米管因其比表面积大、电学性能优异等特点在气体传感器上极具应用潜力，其中表面修饰改性是进一步提升其气敏性的有效手段。金属氧化物作为碳纳米管常见的修饰材料可以整合两者的优点，具有灵敏度高、响应快、能耗低的特点，是近些年气体传感器领域的研究热点，而这一热点的关键问题是金属氧化物涂层的尺寸效应及对气体的选择性。对此，本项目拟采用磁控溅射的方法控制金属氧化物涂层的厚度，首先通过多种杂化材料间的横向比对，找到金属氧化物的特性、尺寸与杂化材料气敏性之间的规律性联系；再利用多糖分子对金属氧化物/碳纳米管杂化材料进一步修饰，考察多糖的尺寸、表面改性、各组份比例等可控因素对传感器性能特别是选择性的影响，并结合组份间的界面效应讨论传感器机理。本项目有助于深入了解修饰材料的微观结构对气敏性的影响机制，可为碳纳米管气体传感器的发展夯实基础。

拟重点考察多糖分子对碳纳米管基杂化材料气敏性的影响，因此选取壳聚糖和氧化锌分别作为多糖和氧化物的典型代表，氧化锌为第一级碳纳米管修饰材料，壳聚糖为第二级修饰材料。结果发现，壳聚糖/氧化锌/碳纳米管三元复合材料的气敏性显著优于相应的二元或一元体系，且传感器具备很高的抗干扰能力。气体分子的吸附引起多糖结构的变化进而影响电子传递过程是传感器电阻变化的主要原因。吸附引起壳聚糖膨胀，进而引起内部的碳纳米管导电路径发生变化，电子在碳纳米管间的跃迁距离增大，电阻上升；解吸以后，分子链之间的极性基团又会重新相互作用，产生收缩效应，原有的导电通路得以恢复，电阻下降。项目的结果可为多糖在气体传感器上的应用研究提供有力的理论和经验支撑。项目资助之下，已申请了专利两项，发表SCI期刊发表论文5篇。