Versatile preparation of graphene-based nanocomposites and their hydrogen adsorption

We report the facile and versatile preparation of graphene-based nanocomposites of magnetite, silver, titania, nickel, and silicon by solid state mechanical mixing. The composites were directly employed for nitrogen and hydrogen gas adsorption studies at 77 K and equilibrium pressure of 1 atm. Under the experimental conditions the chemically synthesised graphene support had a solid state BET surface area of 499 m2/g and a total reversible hydrogen uptake of 0.5 wt.%. Among our prepared nanocomposite samples, the silver nanoparticles promoted the most significant increase in hydrogen uptake per metre squared of material by 30% when compared to the parent graphene sample. However, the total hydrogen uptake by weight percentage in the studied graphenic materials remains low. The hydrogen storage capacity observed for the graphene nanocomposites can be qualitatively accounted for by considering the contributions of the catalyst particles on the hydrogen storage, the contact between catalyst and graphene, and the structural nature of the graphene surface.