Comparative Study of the Synthesis and Characterization of Reduced Graphene Oxide (RGO) Using an Eco-Friendly Reducing Agent

In this work, the reducing action of four reducing agents—ascorbic acid, inorganic salt, sodium hydrosulfite and polysaccharide—was investigated. Some reducing agents, in addition to being environmentally friendly, are good substitutes for dangerous chemicals used industrially. Graphene oxide (GO) was synthesized by the modified Hummers method and was reduced with ascorbic acid (RGO-AA), inorganic salt (RGO-SI), sodium hydrosulfite (RGO-HS) and polysaccharide (RGO-PS). The microstructural, morphological, optical, electrochemical and thermal properties of GO, RGO-AA, RGO-SI, RGO-HS and RGO-PS were characterized by x-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy/attenuated total reflectance (FTIR-ATR), x-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM)/energy-dispersive x-ray spectroscopy (EDS), field-emission scanning electron microscopy (FEG-SEM), UV–Vis, zeta potential, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The conclusive results showed that the four agents demonstrated reducing capability. It was observed that the reducing agent derived from inverted sugar (polysaccharide) was the most efficient because it presented a reduction in GO with fewer microstructural defects, a lower number of sheets, and electrochemical and thermal properties superior to the properties obtained from conventional reducing agents. Therefore, with these impressive results obtained with polysaccharide, it was concluded that an effective GO reducing agent was obtained using this green and ecological product, resulting in a reduced graphene oxide (RGO) with few sheets and fewer defects and, consequently, with greater supercapacitor application potential.