Preparation of graphene oxide and characterisation using electron spectroscopy

The G-O3 and G-PP graphene oxide samples contain a low amount of C sp3 bonds and carbon-oxygen groups in comparison to graphene oxide prepared by the “wet” chemical methods. Oxidation of commercial graphene platelets powder, especially in air plasma, leads to increasing surface C sp3 and significantly bulk C sp3 contributions, indicating intercalation by oxygen groups. The intensity ratio of the REELS π + σ C sp2 bulk to the C sp2 surface energy loss peaks, decreasing in the order G>G-O3>G-PP, indicates exfoliation of layers in G-O3 and G-PP by oxygen functional groups and water with decreasing average number of layers in graphene oxide nanostructures due to oxidation. Although, the “wet” chemical methods are more effective for oxidation leading to a larger amount of C sp3 and oxygen groups, the proposed methods of oxidation by ozonation and in air plasma are inexpensive, safe, effective, environmentally friendly and do not result in toxic chemical waste products.