Strategies for reduction of graphene oxide – A comprehensive review

Graphene continues to draw considerable research and commercial interest due to its applicability in a variety of industries. There have been various approaches developed to produce high quality graphene in commercial quantities in order to be able to meet the ever-increasing demand from industry. Despite over a decade of research and various examples of lab-scale success in producing highly pure single graphene sheets, there remain considerable challenges in translating them into a commercial success in terms of their large-scale production. To this end, reduction of graphene oxide (GO) is considered the most viable alternative approach to produce highly quality graphene. However, there have been numerous reports documenting a variety of reductants in the literature, making it quite difficult to assess and compare these strategies from the perspective of large-scale commercial production. In this review, we present a critical survey of various reduction methods adopted towards the reduction of GO enabled by chemical, plant extracts, microorganisms and photoreduction with special emphasis on their reduction mechanism and electrical conductivity of the resulting rGO. We also provide a prospective to draw attention to the considerable challenges persisting towards the structural and electronic properties of the synthesised rGO which is limiting the true commercial translation of these materials.