Reduction of Graphene Oxide via Modified Hydrothermal Method

The chemical reduction of graphene oxide (GO) typically involves highly toxic reducing agents that are harmful to human health and environment. Moreover, complicated surface modification is often needed to avoid aggregation of the reduced GO during reduction process. In this paper, GO was synthesized by modified Hummer's method. Modified hydrothermal method was utilized to prepare reduced GO in pH value of 11 adjusted by NaOH at 140 °C for 6 h under continuous stirring. FTIR, Raman, SEM and XRD analyses are performed, which reveal that the labile oxygen functional groups are progressively eliminated, thereby partially restoring the π-conjugated network. Raman spectra show G to D band progression. Furthermore, XRD results confirm proper GO reduction. Carbonyl, carboxyl, ether, and phenolic groups are found to be thermally stable, which hinders complete deoxygenation of GO and makes their dispersion in water stable. In modified hydrothermal method, pressure can be controlled efficiently and temperature is lower than simple hydrothermal method. Also, the final product has homogenous structure, thus facilitating the use of graphene-based materials for large-scale applications.