Novel Graphene-Based Reversible Physisorption Materials for High Hydrogen Uptake

Carbon-based nanomaterials (graphene, carbon nanotube, microporous carbon, graphitic carbon etc.) are excellent H 2 storage materials due to high molecular H 2 uptake at the micropores and large H 2 adsorption at the graphene network via the formation of dipoles in H 2 molecules through London dispersion forces. On the other hand, incorporation of transition metal nanoparticles within the nanocarbon network facilitates dissociation of H 2 molecules into constituents H-atoms over the metal nanoparticles, followed by diffusion into the carbon nano-matrix via ‘spill-over’ effect for polarization/hybridization of metal-hydrogen to create high H 2 binding energy for high hydrogen adsorption. Therefore, a nanocomposite of graphene-microporous carbon-metal nanoparticle network is expected to deliver excellent H 2 uptake capacity and acts as a novel reversible physisorption material for hydrogen storage applications, which is very important for sustainable renewable energy integration. A simple, cost effective sputtering method is used to fabricate metal incorporated graphitic microporous carbon film and differential resistance measurement showed high H 2 uptake. Average number of graphene layer formation is dependent on sputtering parameters, which manifest bi-to-multilayer graphene. With increase in graphene layers, H 2 adsorption also increases due to a fourfold effect: higher molecular hydrogen uptake at the graphene layers, more active sites into the micropores, promotion of molecular dissociation into atomic hydrogen by the metal nanoparticles, and the formation of hydrogenated carbon via destruction of the π-bonds.