石墨烯模板法组装SnO2纳米超结构及其高灵敏气敏特性研究

Metal oxide semiconductor gas sensors are predominant solid-state devices for detecting inflammable, explosive, toxic or noxious gases, which has many advantages such as low cost, easy production, long life and wide detection range. However, the performance of such sensors is significantly influenced by the morphology and particle size. According to the previous reports, when the particle size of SnO2 is less than 6 nm, the crystalline SnO2 becomes highly sensitive to ambient gas molecules. Besides, the structure of hollow and porous nanosphere may also cause high sensitivity. Yet, the previous reports only make attention of either of the two aspects. If an optimal combination of small size effect and the structure of hollow and porous nanosphere, super-sensitive gas sensing properties will be acquired. In this project, we will synthesize SnO2 nano-superstructure by the template of graphene by which small size of SnO2 nanoparticles may be obtained. Graphene is a flat monolayer of carbon atoms tightly packed into a two- dimensional (2D) honeycomb lattice, which is flexible. So, SnO2/graphene nanocomposites composed of sub-6 nm SnO2 nanoparticles can be synthesized by template of graphene and then the nanocomposites may be packed onto sphere-like templates. After removing the template materials, a hollow and porous sphere structure of SnO2 will be acquired and the gas sensing properties will be investigated in this project.

半导体气敏传感器具有寿命长、检测范围广、成本低、功耗低和制作简单等特点，已被广泛用于易燃易爆、有毒有害气体的检测，是目前产量最大、应用最广的气体传感器之一。从半导体气敏材料微观结构的角度讲，影响传感器灵敏度的因素主要有两个方面：颗粒尺寸和微观形貌。以往文献都只是关注其中一个方面，没有综合考虑。本项目拟以SnO2为例，从纳米颗粒尺寸和纳米颗粒组装成的微观形貌两个方面研究提升传感器灵敏度的纳米超结构材料。以石墨烯为模板，构筑由超小尺寸SnO2颗粒组装成的多孔空心球结构，从而大幅提高SnO2气敏传感器的灵敏度。在制备方法上，拟利用石墨烯作为平面材料的表面张力制备尺寸均匀、超小的SnO2颗粒，探讨SnO2颗粒的生长机理；利用石墨烯作为最薄材料的柔韧性包裹在球状模板表面，再通过热处理去除模板材料，制备由均匀、超小的SnO2颗粒组成的多孔空心球纳米超结构，并研究其在挥发性有机污染物检测中的气敏特性。

本课题按计划完成了预期目标。当半导体纳米材料的晶粒尺寸接近或小于耗尽层厚度时，传感器的敏感电阻为耗尽层控制方式，灵敏度将大幅提高。但是，晶粒尺寸越小越容易团聚，因此，制备均匀、稳定的耗尽层厚度纳米结构是半导体传感器领域的瓶颈问题。本课题以石墨烯作为模板，利用其平面位阻作用制备了均匀、超小SnO2纳米颗粒与石墨烯的复合物，研究了小尺寸纳米结构的分级组装方法，揭示了贵金属纳米颗粒的气敏增强机理，制作了超灵敏的纳米结构气敏材料，实现了对乙醇、丙酮等挥发性有机污染物的超高灵敏检测。此外，半导体气体传感器的最佳工作温度一般都在200-400℃，加热条件不仅增加了传感器的功耗，也限制了半导体传感器在一些易燃易爆危险场合的应用。本课题在多孔单晶ZnO纳米片气敏材料的基础上构筑了单个纳米片传感器件，实现了紫外激发条件下的室温传感检测，为研制室温半导体气体传感器开辟了一条有效途径。在本课题的资助下共发表论文26篇，其中SCI论文24篇，中科院一区论文9篇，二区论文3篇，申请国家发明专利2项；获安徽省自然科学一等奖、中国分析测试协会科技青年奖、安徽省自然科学优秀学术论文奖、《功能材料》杂志优秀论文奖和英国物理学会杰出审稿人奖等奖励；培养研究生4人。