Green and facile production of high-quality graphene from graphite by the combination of hydroxyl radical and electrical exfoliation

Abstract

A novel, simple and efficient method, involving the combination of hydroxyl radicals and electrical exfoliation of graphite for the green production of high-quality graphene from graphite, was developed for the first time. The process parameters were optimized by single factor experiments; the optimal conditions were 4.0 g graphite dosage, sodium chloride solution with concentration of 5.0% (w/v), applied current strength of 10 mA, and air flow rate of 1.0 L h⁻¹ for 3 h. Under the optimized conditions, graphite was successfully exfoliated to graphene. SEM and TEM results revealed that the graphene product has the characteristic features of a thin-layer graphene sheet. XRD results showed that the graphene products still maintained the structure of the carbon atoms or molecules. FT-IR and Raman results indicated that the products have the characteristic peaks and absorption peaks of graphene. AFM imaging results reveal that the layer number of the graphene product obtained by this method is about 3, while the graphene products from the individual hydroxyl radical oxidation and electrical exfoliation processes were 50 and 133 layers, respectively, under the same experimental conditions. The good quality of the graphene product can be attributed to the synergistic effect between the strong oxidation of the hydroxyl radicals and electrical exfoliation. The proposed method has the advantages of simple operation, mild preparation conditions, non-utilization of aggressive reagents, recycling of the reaction medium, etc. Thus, this method could serve as a green and efficient alternative for the production of graphene and its derivatives in industry.