Hybrid graphene-based materials and its catalytic activity toward hydrogen sorption

Thanks to unique material's properties, a remarkable research attention has been focused on graphene. In this research work, the Radio frequency (RF) sputtering technique process parameters were varied to achieve the well dispersed nanoparticles onto graphene sheets in the range of 5–10 nm to enhance the hydrogen sorption. On such scale, quantum size effects enter can play lowering the H2 desorption temperature from 400 °C typical of bulk Mg hydrides to 140 °C. In this context, the Magnesium (Mg) nanoparticles were decorated onto graphene sheets by varying the powder vibration frequency during the deposition process. X-ray diffraction (XRD) results demonstrate that the d spacing of graphene sheets was increased with decoration of Mg nanoparticles. Additionally the three characteristic peaks correspond to (001), (002) and (101) planes of hexagonal structure of metallic Mg were also observed. Transmission electron Microscope (TEM) micrographs revealed that the decorated Mg nanoparticles onto graphene at high powder vibration frequency were uniformly distributed over the entire sheet of graphene. Raman spectra showed that with the interaction of graphene with Mg nanoparticles the G and 2D peak were shifted 9.81 cm−1 and 8.2 cm−1 to higher wavenumbers, suggesting p doping of graphene. X-ray Photoemission Spectroscopy (XPS) results revealed that high concentration of Mg nanoparticles was obtained with high powder vibration frequency. The hydrogen up taking capacity for the decorated graphene sheets with Mg nanoparticles was about 6.00 wt% in whole composite. However, the up taking hydrogen storage capacity of the only Mg nanoparticles was 7.4 wt%.