Safer modified Hummers’ method for the synthesis of graphene oxide with high quality and high yield

We report on an improved method for the synthesis of graphene oxide based on the modified Hummers' method proposed by Marcano et al Different steps of the process were optimized. First, the concentration of the reactants and the reaction conditions were optimized to improve the efficiency of the oxidation process of graphite. The Raman spectrum of the GO shows the typical D and G typical of graphite oxide materials. The contribution of the area under the band D to the total area is 98%, confirming that almost the whole graphene was oxidized (high oxidation yield). Furthermore, the quantification of the C 1s XPS spectrum of our GO nanosheets indicates that about 77 wt% of oxygen in the form of oxygenated groups is bonded to the carbon nanosheets. Second, the reaction time was minimized to 12 h, without compromising the quality (as confirmed by micrography). Third, the production of toxic gases has been reduced. Fourth, a thermal treatment was introduced instead of the vacuum drying procedure traditionally used, greatly diminishing the overall graphite oxide processing time that includes: the reactant preparation, graphite oxidation process, rinsing and dispersion procedures, and drying (the drying time went from 12 h to 2 h). Reducing the total time by a half, compared to other methods, is an important finding considering scaling for industrial production.