Evolution of Plasma-Excitation Mechanisms in the Process of the Thermal Reduction of Graphene Oxide

Abstract

The dynamics of X-ray photoelectron emission spectra is studied in the region of the 1s carbon line with increasing treatment temperature for graphene-oxide samples. It is established that, as the degree of oxide reduction increases, the role of the mechanism related to energy losses for the excitation of π-plasmon oscillations produced in the presence of sp2 bonds in the carbon sample increases. Spectral analysis shows that the π-plasmon peak is manifested in the spectra of samples annealed at temperatures exceeding 200°C. When determining the differential cross sections for inelastic electron scattering, the difference between the energy losses in the surface sample layers and the homogeneous bulk located far from the surface is taken into account. The obtained spectra are compared with those of multilayer graphene and pyrolytic graphite. It is shown that the analysis of graphene oxide using X-ray photoelectron spectroscopy gives a picture on a nanometer scale. The obtained data can differ noticeably from the Raman spectroscopy data corresponding to the millimeter scale.