A comparative study of graphene oxide: Hummers, intermediate and improved method

Among 2-D nanostructures, graphene oxide is considered as the most attractive precursor nanomaterial for the utility of graphene in a variety of applications. There are problems associated with its mass production, which demands development of better and easier synthetic protocols. In addition, a chemical approach with a better control over degree of oxidation and nature of functionalities is simultaneously crucial for designing their structural modifications and the corresponding applications. Herein, three types of GOs are prepared by Hummers', Intermediate and Improved method. A primary reaction step in GO synthesis is the formation of graphite intercalation compounds (GICs). The efficiency of oxidation and intercalant efficiency, non-oxidative Bronsted acid H3PO4/H2SO4 and H2SO4 are studied and properties are compared with the classical intercalant, H2SO4/NaNO3. A modulation in degree and nature of oxidative defects, flake size and stability of aqueous dispersion is observed, as supported by various analytical techniques. Depending upon the reaction conditions, the synthesized GOs revealed predominance of different type of oxidative functionalities and thereby reflected in associated physical properties, which is helpful to guide their usage for specific applications.