Surface Modification of Reduced Graphene Oxide by Electron Bombardment Characterized by Multimodal Spectroscopic Analysis

Graphene is a potential candidate for hydrogen storage. One method of producing graphene in commercial quantities is through reduction of graphene oxide powder. We study the hydrogenation of reduced graphene oxide (rGO) powders by electron irradiation in the keV energy range using X-ray Photoelectron Spectroscopy (XPS). We examine whether electron-molecule interactions induced through electron bombardment can modify rGO's surface chemistry by introducing newly functionalized hydrogen-containing groups while maintaining graphene-like structural integrity. To do so, rGO powder dispersed in SiO2 was irradiated with electrons in an ultra-high vacuum with a current of 2 to 2.5 nA, a dosage of 3 × 1017 electrons/cm2, and beam energy of 1.5 keV. The irradiated samples were analyzed using the XPS, revealing a 47% reduction in C-O bonds relative to the C-O/C=C area ratio, demonstrating electron bombardment as a tool for further reducing chemically-reduced graphene oxide, with an additional decrease in C-C/C=C area indicating a partial restoration of graphitic structure. Separately, upon irradiation of graphene oxide with similar parameters, we observed visible surface modification in the sample at specified beam energies, where this visible contrast allowed XPS analysis of its irradiated, non-irradiated (shadow) region, and the pre-irradiated region. Further analysis of this study will involve the use of Thermogravimetric analysis, and any available results from these experiments will also be presented.