Temperature-dependent properties of metastable graphene oxide

Monolayer of graphene oxide has great potential applications in ion and molecular screening, desalination and purification of water, gas separation, biosensing, proton conductors, lithium batteries, super capacitors and other fields, due to its excellent physical and chemical properties. However, the graphene oxide prepared by chemical and physical methods, such as the commonly used Hummers method is a metastable material. The transformation and regulation of the physical and chemical properties of the final morphology are essential, and systematic research is urgently needed. In this paper, the thermostat treatment method is used to control the metastable transformation of graphene oxide. The relationship of content, type, and morphology with temperature of oxygen-containing graphene oxide are detected by X-ray photoelectron absorption spectroscopy, Fourier infrared absorption spectroscopy, scanning electron microscope, etc.; and the effects of temperature on the stability of solution suspension stability, photon energy band and tensile strength of graphene oxide in the transformation process are analyzed by using Zeta potential, ultraviolet absorption spectrum, tensile force. The quantitative test results show that there exists a phenomenon in which the epoxy phase decreases, the hydroxyl group increases and the overall oxygen content decreases in the metastable transition process of graphene oxide, and the monolayer morphology of graphene oxide does not change significantly in this process. This structural transformation, however, greatly enhances the viscosity and hydrophilicity of the suspension, and remarkably reduces the energy band and considerably raises the tensile strength enhancement effect. When the transformation process is long enough, the hydrophilicity of the graphene oxide will decrease and precipitate. It is indicated that a further dehydration transition occurs between the hydroxyl groups. In addition, in the paper we also analyze the effect of constant temperature treatment time and concentration of suspension on this transformation process. The relevant research results are helpful in understanding the performance change of metastable graphene oxide suspension with temperature, and have certain reference value for the specific application of graphene oxide.