Green synthesis and characterization of reduced graphene oxide

Abstract

The distinctive chemical, physical, thermal and mechanical properties of graphene made it widely recognized material in wide-ranging field of science and technology. Generally, the synthesis of graphene or reduced graphene oxide (rGO) requires two main steps. The first step involves the oxidation of graphite to graphene oxide (GO) and in the second step, reducing agents or reductants contribute to the reduction of GO to form rGO. A large number of reducing agents have been applied to synthesize rGO such as hydrazine, hydroxyl amine, sodium borohydride, etc. However, the hazardous nature of such reducers created a space for the research on green reducing agents for rGO synthesis. This study introduces the low-cost green synthesis of rGO via green reducing agents such as eucalyptus hybrid extract, thiourea, lemon extract and starch. Among all the green reductants, eucalyptus hybrid extract exhibited the remarkable reduction of GO, as confirmed by VU-visible spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction results. The absorption peak of rGO-eucalyptus is appeared at 272 nm, whereas the d-spacing between layers is determined to be 0.364 nm. The obtained band gap of rGO-eucalyptus (2 eV) is found less as compared with other reducing agents such as thiourea, lemon extract and starch. The stretching vibration of oxygen functionalities appeared in FTIR of GO, is disappeared after reduction with eucalyptus extract. The flavonoid components of eucalyptus extracts are antioxidant in nature and hence, work as reducing agents.