Synthesis and characterization of a large-quantity of functionalized graphene from graphite by a facile bubble-exfoliation method

Abstract

In this work, functionalized graphene (FG) was synthesized based on an improved bubble-exfoliation method from cheap defective graphite. By using the improved method, we synthesized a significant amount of FG in a short time while maintaining the acid usage at a low level compared to previous works. Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and ultraviolet–visible spectroscopy (UV–Vis) techniques validated the oxidation effect of the synthesis process on FG, which is in line with the addition of functional groups to it. Transmission electron microscopy, atomic force microscopy, Raman and XRD characterizations showed that FG mainly consists of a thin few-layer structure. X-ray photoelectron spectroscopy (XPS) analysis was also in agreement with the chemical structure validated by FTIR, Raman and UV–Vis, indicating that the functional groups of FG are primarily hydroxyls. Furthermore, it was revealed that the presence of pentagonal–heptagonal defects, confirmed by XPS results, in the graphite source have a significant impact on the success of the synthesis route as the defects play the role of activators for persulfate in the oxidation process.