Scanning Electron Microscope (SEM) accompanied with energy dispersive X-ray spectroscopy (EDS) was used to characterize the morphology and elemental distribution of CFs and graphene flakes, using a TESCAN MIRA3 SC. A JPK NanoWizard atomic force microscope (AFM) was adopted for thickness characterization of the graphene flakes, using the QI mode. A PANalytical X'Pert Pro diffractometer equipped with a Cu Kα radiation source was used to obtain the X-ray diffraction (XRD) patterns at the range of 2θ = 3.02° to 99.98°.