Synthesis of Graphene by Reduction of Graphene Oxide Using Non-Toxic Chemical Reductant

Abstract

Recent advancement in research has introduced graphene as an excellent material because of its unique mechanical, chemical, thermal, optical, and electrical properties. Graphene sheets can be successfully prepared by exfoliation of bulk graphite using scotch-tape method or by chemical vapor deposition. However, it is difficult to yield a scalable quantity of graphene by these routes. A common approach to produce scalable quantities of graphene is chemical oxidation of graphite and, thereafter, its reduction to graphene or reduced graphene oxide (RGO). The use of chemical hydrazine is most common for the purpose of reduction. But it is very toxic and detrimental to both human and environment. Thus, there is a need to explore non-toxic reductant and a facile technique for RGO synthesis. In the present study, a non-toxic chemical reductant sodium hypophosphite monohydrate (NaH₂PO₂·H₂O) has been used for the reduction of GO to RGO. A detailed characterization of GO and RGO was carried out by using field emission scanning electron microscope (FESEM), Raman spectroscopy, UV-visible spectroscopy, and thermo-gravimetric analyses (TGAs). The morphology of GO and RGO as observed by FESEM shows thin wrinkled sheets of GO and RGO. Further analysis by energy dispersive X-ray spectroscopy illustrates that % C/O (in at.) in RGO is three times that of GO (% C/O=2.69). The Raman spectra confirm the removal of oxygen functional group from GO as higher I_D/I_G ratio is noticed for RGO. Also, the absence of shoulder peak at ~300 nm in UV-visible spectroscopy measurement confirms the efficient reduction of GO to RGO. The TGA reveals the higher thermal stability of RGO with lesser weight loss.