Graphene oxide and its chemical nature: Multi-stage interactions between the oxygen and graphene

In this paper, we have comprehensively reviewed the results of recent studies on novel unique material, which is a product of oxidation of graphene or graphite and generally known as graphene oxide. The main focus has been to perform critical analysis and understand whether a monomolecular layer of graphene with attached oxygen atoms and/or various oxygen-containing functional groups (epoxy, carbonyl, carboxyl or hydroxyl) can be considered as an independent phase of a substance, i.e. an oxide. The arguments towards the verification of multi-stage interactions between the oxygen and graphene have been highlighted. The definition of graphene oxide has been analyzed considering proposed structure models, approaches utilized for its preparation, properties of graphene-based materials and their applications in advanced microanalytical platforms, environmental security systems, biosensors and chips for mass spectrometry. Moreover, to support the discussions on the pros and cons, we carried out analyses of the graphene oxide-based material in our laboratory and provided the experimental findings. The chemical nature of the combined structure of oxygen-containing functional groups and a single-layer of carbon atoms is of particular importance in the physical chemistry of surfaces and dispersion systems. Thus, this review is expected to improve a modern understanding of the surface chemistry of nanomaterials and also will provide an opportunity to better analyze the stability of their properties that will be important in many application fields, including the development of micro- and nano-devices based on the modified graphene.