跨尺度多孔三维还原氧化石墨烯复合物网络微纳结构调控及其气敏传感器研究

Graphene can be considered as an excellent sensing material due to its unique properties, however, the majority of graphene membrane sensors generally studied nowadays have layered structures with sheets stacking together, which will prevent the gas from penetrating into the surfaces of inner graphene sheets, accompany with the adsorption of gas molecules and the delay of their movements, and consequently affect the performance of the sensing devices. In this project, we will study a novel chemically reduced graphene oxide (rGO) sheets based nanocomposites with multiscale porous three dimensional structures for gas sensing. Based on the prelimilary studies, the difficulties focused on the control of micro/nano structures of this sensing material will be cracked down in this project. And the parameters for the processes of oxidization, self-assembly, etching, and electrochemical deposition will be studied as well, in order to fabricate the sensing devices with the novel micro/nano structures. By the combination of spatial confinement self-assembly technique and vacuum freeze drying method, the rGO foams can be easily prepared. The macropores and mesopores can be formed during this process, which can increase the exposure of rGO sheets to the analytes.Subsequently, etching vapor was used to etch the rGO sheets, the micropores can be in situ formed and controlled on the surfaces of rGO sheets, which will greatly improve the sensing performance of single rGO sheets, due to the fact that the pore diameter of rGO sheets is close to the molecular mean free path of analyates. Further deposition of metal, metal oxide or conducting polymers on the surfaces of porous rGO networks can be achieved through electrochemical depositon technique, in order to improve the selectivity and sensitivity of the final rGO sensors. During the gas detection process, electric charge (elctron or hole) can transfer to rGO sheets, and then fast travel will occur due to the network of rGO, which will further improve the sensitivity of the resultant sensing device.Since the micro/nano structure plays a key role in the final sensing performance of the device, the dynamic law of the growth of the functional materials mentioned above on the surfaces of porous rGO 3D network will be studied in detail, and their growth mechanism will be developed as well, as a result, the growth of these functional materials on the rGO networks can be controlled. In addition, the relationship between processing parameters and the sensing properties of the resultant composite 3D networks will be studied. And the structures of the networks will be optimized as well. Finally, the sensing mechanism of the resultant composite 3D structures will be developed, which will benefit for the fabrication of high performance rGO sensing devices with low cost and scalability characteristics, and hold a great potential in the realistic gas detection fields.

石墨烯以其优异性能成为制作气体传感器的理想材料，然而，目前普遍研究的石墨烯薄膜气体传感器中片层堆砌易形成致密结构，其易阻碍和粘滞气体分子，从而不利于传感器的气体检测。本课题旨在研究跨尺度多孔三维还原氧化石墨烯（rGO）复合物网络微纳结构调控的关键难点问题，通过探索研究氧化、组装、刻蚀及电化学沉积等工艺参数，实现以下独特结构器件的可控构建：1）跨尺度多孔rGO三维网络，其中，氧化石墨烯还原组装形成大孔和中孔，避免片层堆砌以利于其与气体充分接触，后渗入刻蚀剂蒸汽原位可控刻蚀rGO片形成微孔，利用其孔径与气体分子平均自由程接近来实现器件对气体超灵敏检测；2）原位沉积功能材料，在气体选择性检测同时，电荷转移至rGO后易在此连续网络上无阻碍传输，从而进一步提高其灵敏度。研究多孔rGO三维网络及各功能材料的生成机制，优化复合网络结构，建立其气敏机制，为制备和应用低成本、高性能rGO气体传感器奠定基础。

石墨烯以其优异性能成为制作气体传感器的理想材料，然而，目前普遍研究的石墨烯薄膜气体传感器中片层堆砌易形成致密结构，其易阻碍和粘滞气体分子，从而不利于传感器的气体检测。本课题旨在研究跨尺度多孔三维石墨烯复合物网络微纳结构调控及气敏机制。以镍纳米线薄膜为基底，以甲烷为碳源，采用化学气相沉积法在模板表面原位生长制备出高比表面积的石墨烯，结合化学刻蚀，从而得到三维石墨烯网络，经构效关系研究优化三维网络气敏结构；以高比表面积的三维石墨烯网络为模板，采用水热法原位生长金属氧化物、金属硫化物和导电聚合物，构建石墨烯复合三维网络，利用形成的异质结作为活性位点，大幅提升三维网络的气敏性能。通过探索生长工艺和刻蚀工艺过程中的可控因素与跨尺度多孔石墨烯三维网络微纳结构的关系，阐明跨尺度多孔石墨烯三维网络的形成机理；通过研究探索金属氧化物、金属硫化物及导电聚合物等功能材料在跨尺度多孔石墨烯三维网络上沉积生长的动力学规律，实现各功能材料的可控生长，建立各功能材料在复合网络中的沉积生长机制；通过研究探索生长工艺参数、刻蚀工艺参数及沉积参数等与三维复合网络结构气敏特性间的内在联系，研究多孔石墨烯三维网络及各功能材料的生成机制，优化复合网络结构，阐明跨尺度多孔三维石墨烯复合物网络微纳结构的气敏机制，制备出跨尺度多孔三维石墨烯复合物网络微纳结构高性能气敏传感器，检测极限达ppt量级，为制备和应用低成本、高性能石墨烯气体传感器奠定基础。