A Novel Approach to Synthesize Reduced Graphene Oxide (RGO) at Low Thermal Conditions

Abstract

Reduced graphene oxide (RGO) or graphene as it is commonly referred to is currently the most promising nanomaterial with potential applications. Synthesis of RGO starts with oxidation of graphite to graphene oxide (GO) which is further reduced either by chemical or thermal means. However, chemical reduction of GO to RGO involves the use of toxic chemical reagents which are not environmental friendly. Hence, in this work, low-temperature thermal reduction has been utilized to obtain high-quality RGO from GO effectively at a temperature of only 50 °C. The precursor of RGO which is GO is synthesized by modification of Improved Hummer’s method (Marcano et al. in ACS Nano 4(8):4806–4814, 2010), a non-toxic and non-explosive method of GO production. The highly exothermic reactions in producing GO are controlled by using ice baths with magnetic stirring. The prepared samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, Scanning electron microscopy and Energy-dispersive X-ray spectroscopy. All four characterizations confirm the efficient oxidation and reduction that has taken place to produce GO and RGO-4. (RGO formed on the 7th day of the reduction process.) XRD peak of GO at 10.46° corresponding to (001) plane indicating an interplanar spacing of 0.80 nm confirms the proper oxidation of graphite to GO. However, after thermal reduction at 50 °C the 2θ peak of GO at 10.46° shifts to 2θ = 24.15° with an interplanar spacing of 0.36 nm that confirms the formation of RGO-4 with retention of most of the sp2 structures by proper reduction of the oxygenated functional groups of GO. The GO produced is hydrophilic in nature due to existence of large number of oxygen-containing functional groups as shown in FTIR analysis. Raman results show that after reduction of GO to RGO-4 at 50 °C, the ID/IG ratio decreased significantly from 1.93 of GO to 1.00 of RGO-4 indicating highly reduced defects density in RGO-4.