Effects of initial graphite particle size and shape on oxidation time in graphene oxide prepared by Hummers' method

The effects of initial graphite particle size and shape on oxidation time of graphite prepared by Hummers' method have been investigated. The oxidation was performed on three series of graphite particles, clod powder with two different sizes of 18 and 6 μm, and flake shaped powder with an average particle size of 25 μm. The samples were characterized by means of particle size analyzer, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The ratio of XRD graphite oxide peak intensity to graphite peak intensity was considered as an indicator of the oxidation degree. It was observed that the oxidation time has a critical dependence on the initial graphite particle size and shape. While the oxidation of the clod samples was completed in several days, the oxidation of flake powder was completed just in 2 h. These findings help researchers to save time by choosing the particle size and shape of initial graphite powders.