Study On Spectroscopic Characterization Of Graphene

The unique properties of graphene,such as high charge transfer rate,high light transmittance,high strength,high specific surface area and good thermal conductivity,make it a promising candidate for applications in the field of electronic devices,energy storage devices,composite materials,sensors,etc.With the commericialization of graphene products,accurate measurement of graphene is urgently needed.The quality of graphene is directly related to synthesis process and show a strong influence on the performance of final products.Therefore,the quality of graphene needs to be monitored and accurately characterized.Spectroscopic characterization can provide a effective and efficient technique of graphene,which may facilitate the application of graphene in various fields.At present,chemical vapor deposition(CVD)and chemically reduced graphene are two of the most commonly used preparation methods of graphene.Hence,graphene films and graphene powders prepared by these two methods are studied in this paper.The main study contents of this paper include:1.Rapid and accurate characterization of CVD graphene film with impurities was studied.CVD graphene film was investigated by Raman imaging.The layer number of graphene film was determinated by evaluating the Raman mapping images of the position of G peak,2D peak and IG/I2 D.The optical image and the Raman mapping images of IG and I2 D were used to identify single-layer graphene and folded bi-layer graphene.The Raman mapping image of ID/IG was used to determine the amorphous carbon and crystalline carbon.The edge effect of graphene was studied by the Raman mapping images of the position of 2D peak,the FWHM of 2D peak and IG/I2 D.The result of Raman imaging characterization was verified by atomic force microscopy.As concluded,Raman mapping may provide a fast,simple and nondestructive inspection technique for industrial applications to monitor and control the quality of CVD grown graphene.2.The effect of temperature on the stacking bilayer graphene was studied.The interlayer coupling states of stacking graphene films and CVD grown graphene films at room temperature were studied by Raman spectroscopy.The effect of SiO2/Si substrate on the stacking bilayer graphene and CVD bilayer graphene at different temperatures was studied.The influence of temperature on the interlayer coupling states of stacking bilayers graphene / substrate and CVD grown bilayer graphene / substrate was studied.The temperature coefficient of the position of G peak and the FWHM of 2D peak at 25°C to 250°C and 250°C to 400°C were calculated.3.The differences between graphene oxide and reduced graphene oxide was studied by Raman spectroscopy,FTIR spectroscopy and UV-Vis absorption spectroscopy.4.The spatial resolution of confocal microprobe Raman spectroscopy is studied.Three-dimensional Raman mapping of true confocal and pseudo-confocal microprobe Raman under the same conditions were tested by a dispersion of 500 nm polystyrene beads(NIST Traceable Particle Size Standard).The three-dimensional Raman mapping images of polystyrene beads were used to fit the horizontal and axial spatial resolution of true confocal and pseudo-confocal microprobe Raman.The horizontal and axial spatial resolution under the same conditions are also obtained by the theoretical calculation.The spatial resolution of the two methods is compared.