Role of interlayer spacing and functional group on the hydrogen storage properties of graphene oxide and reduced graphene oxide

Hydrogen storage properties of the derivatives of graphene, graphene oxide/reduced-graphene oxide are studied in this paper. Modified Hummer's method was adopted for synthesis of graphene oxide (GO) and reduced-graphene oxide (rGO). The morphology of GO/rGO was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The presence of C=O and -OH group in the Fourier transform infrared (FTIR) spectrum and G-mode and 2D-mode in the micro-Raman studies confirmed the synthesis of the GO and rGO. Furthermore, the structural investigations using powder x-ray diffraction (XRD) reveals the hexagonal crystallographic phase of GO/rGO. The hydrogen storage capacity of the GO/rGO sample is measured using indigenously fabricated high pressure hydrogen storage Sieverts' type volumetric setup at room temperature and pressure up to 80 bars. In present experimental investigations, GO was found to exhibit better H₂ uptake capacity (1.90wt.%) as compared to rGO (1.34 wt.%) at room temperature. It can be said that the oxygen functional groups work as spacers in between the graphene layers and increase the inter-layer space which in turn accumulate more number of hydrogen molecules on surface of carbon nano-sheets.