Structure and properties of graphene oxide during the synthesis process at fixed temperatures

Abstract

Graphene oxide (GO) is the most versatile derivative of graphene; however, the choice of oxidation temperature in the synthesis of GO varies from person to person. In this article, various spectroscopy techniques have been used to characterize carbon and oxygen structure of GO synthesized at fixed oxidation temperatures. Our results show that GO synthesized at a relatively low temperature possesses a decreased D-to-G peak intensity ratio (ID:IG) and obvious single-crystal lattice with a six-fold pattern. As the oxidation temperature increase, a polycrystalline ring structure forms, accompanied by an increasing ID:IG, which indicates that the disorder of the basal plane of GO increases with increasing temperature. Notably, the layer spacing of GO decreases with an increase in temperature, which does not show the expected proportional relationship to the degree of oxidation. Furthermore, chemical composition analysis shows that moderate temperatures contribute to the formation of C–O–C and ≥CO bonds, while the contents of C–OH and sp2 domains decreases, and the content of COOH does not change with temperature. Interestingly, GO is successfully synthesized at 75 °C, indicating that Mn2O7 is not the only oxidant playing a dominant role in the oxidation stage of GO. This work can provide in-depth insight into the viable selection of the oxidation temperature of GO for industrial applications.