Quantitative Analysis of Graphene Sheet Content in Wood Char Powders during Catalytic Pyrolysis

The quantitative characterization of the graphene sheet content in carbon-containing materials is arguable and has not yet been developed. The authors report on a feasible method to characterize graphene sheet content quantitatively in pyrolized carbon materials using an X-ray diffraction (XRD) spectrometer. A direct carbonation at 300 °C followed by catalytic pyrolysis (heat-treatment temperature was set at 700-1400 °C) under a vacuum condition was used for turning wood waste into pyrolized wood char powders. The graphene content in the samples was calculated through an analysis of full width at half maximum (FWHM) of the carbon (100) crystal plane at around 42°-43° in XRD. Results showed that the FWHM and the calculated graphene sheet content of pyrolized wood char powders depended on the heat-treatment temperature, and the FWHM of wood char powder with well-developed graphene sheets (100%) was determined to be 5.0. In addition, the trend to 100% graphene sheet-contained pyrolized carbon powder was obtained at a heat-treatment temperature of 2700 °C. The resistivity of the wood char powder with 100% graphene sheets was predicted to be 0.01 Ω cm, close to our experimental data of 0.012 and 0.006 Ω cm for commercial graphite and graphene products, respectively.