Production of partially reduced graphene oxide nanosheets using a seaweed sap

Large-scale and low-cost production of graphene is widely achieved by the chemical reduction of graphene oxide (GO). In this study, partially reduced GO (prGO) was prepared using a seaweed sap extracted from the red seaweed Kappaphycus alvarezii (1). The seaweed sap is a plant growth stimulant used as a foliar spray. The sap consisted of both organic and inorganic micro and macro nutrients such as plant growth regulators (PGRs), flavonols, choline, glycine betaine and salts of potassium, magnesium, iron, zinc etc. In order to understand the exact component of the sap responsible for the reduction of GO, different formulations of the sap devoid of PGRs and flavonols (2) as well as all organic matter (3) were prepared. It was observed that partial reduction of GO took place in both 1 and 3, while the reduction was not successful in 2. It was concluded that the synergistic effect of both flavonols and transition metals present in the sap was responsible for the reduction. The recovered sap obtained after the isolation of prGO had a similar chemical composition in comparison to the original sap and hence could be used as a plant foliar spray.