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 are studying the hydrogenation of reduced graphene oxide (rGO) powders by electron irradiation in the keV energy range. We study the effects of electron beam irradiation on the absorption of rGO using X-ray Photoelectron Spectroscopy (XPS). The objective is to see if we can modify its surface chemistry by introducing newly functionalized hydrogen-containing groups while maintaining its graphene-like structural integrity. To do so, rGO powder dispersed in a silicon dioxide wafer was irradiated with electrons in an ultra-high vacuum using a current of 2 to 2.5 nA and 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. This demonstrates 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 graphite structure. Additionally, upon electron irradiation of graphene oxide, we observed visible surface modification in the irradiated 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.