Prepration And Characterization Of Graphene Oxide Langmuir-Blodgett Films

In recent years, the study of graphene based materials has been popular and extensive due to its special nanostructure, excellent mechanical, electrical, thermal and optical properties. However, till now, large area deposition of graphene efficiently is still a problem to graphene electronics and more efficient method is needed to settle this problem. In addition to small molecule assembly, non-covalent assembly and copolymerization assembly, Langmuir-Blodgett(LB) self-assembly technology for single molecule film deposition shows promising future as facile method to prepare large area graphene films. Therefore, this paper focuses on the preparation of reduced graphene oxide(RGO) films with LB technology. First, a ultrathin graphene oxide(GO) films was prepared through LB self-assembly, and the preparing parameters were optimized. Then, the obtained GO films was reduced to reduced graphene oxide(RGO) through a novel thermal treatment, and the gas sensitivity of this RGO film was investigated. The main research works are as follows:(1) The optimized preparing parameters: such as solution ratio, temperature and so on, were investigated to obtained stable assembly of GO sheets at air/water interface. The dynamic stability and compressing-recovering performance of GO layers at air/water interface were analyzed. Based on the investigation above, a compact arrangement GO single-layer films was prepared successfully.(2) The SEM, AFM, XRD methods are utilized to characterize the morphology of GO ultrathin layers. The results indicate that the GO sheets showed nanometer size in scale about one nanometer height. The SEM results also show that GO nanosheets exhibited wrinkle morphology and abundant functional group on the sheet surface was confirmed by FT-IR analysis.(3) Based on the optimized preparing process and analysis, a novel process based on steam and thermal treatment was used to reduce the GO into RGO. The results indicate that a more wrinkled morphology was presented in RGO layers due to the thermal treatment. The further investigation confirm that RGO exhibited better conductive ability than GO due to the partly removing of carboxyl group from the GO sheet surface.(4) The gas sensitivity of RGO LB film based sensor was tested in room temperature. It has been found that the RGO showed response to NH3 gas, and showed linear response at a 20-100 ppm concentration range. This RGO LB film based sensor also exhibited excellent recovery ability, and showed better sensing performance than spraying RGO film based device.