NaCl and oxalic acid–assisted solvothermal exfoliation of edge-oxidized graphite to produce organic graphene dispersion for transparent conductive film application

Abstract

Here, we demonstrate a facile method to prepare dispersible few-layer graphene sheets (GSs) by NaCl and oxalic acid–assisted solvothermal exfoliation of edge-oxidized graphite (EOG) in presence of polyvinylpyrrolidone under the synergetic effect of short-time ultrasonication. During solvothermal heating process, NaCl, oxalic acid, and PVP adsorbed on the edge/surface of EOG, and oxalic acid decomposed into CO2, CO, and H2O steam weakening the Van der Waals force between sheet layers of EOG. The solvothermal process results in the exfoliation and reduction of EOG to GSs which can be dispersed in various organic solvents with high concentrations (0.10–2.68 mg/mL) and remained stable for 6 months except dimethyl sulfoxide and acetonitrile. The GS film prepared by vacuum filtration method using EtOH phase GS dispersion had a sheet resistance of 28.0 kΩ/□ at a transparency of 81.2%. This method shows great promise for mass synthesis of few-layer graphene dispersions for thin film applications.