Density Functional Theory Study of Graphene-based Nickel Oxide Composites for Hydrogen Storage

Hydrogen storage with high gravimetric density (GD) and volumetric density (V D) is a contem-porary challenge in utilizing hydrogen energy. Nano particles are ultimate suitable candidates for this purpose because of the large surface area which serves in storing hydrogen with high capac-ity. Accumulation of these nano-particles is a common problem in nano-catalysis, nano-electronics and hydrogen storage. Based upon its unique properties, graphene based serve as a miraculous materials with signi cant potential as a template to prevent the accumulation of nano particles. In this work, nitrogendoped-graphene is employed in order to prevent the accumulation of the small NiO clusters. Two types of NiO clusters are examined; namely, [NiO]2 and [NiO]3. The two clusters exhibited considerable ability to store hydrogen; [NiO]2 can store upto 6H2 molecules with average absorption energy of 0.27 eV, whileas [NiO]3 can store upto 3H2 molecules with average absorption energy of 0.45 eV. The obtained simulated results indicated that though the number of hydrogen molecules stored on [NiO]3 clusters is one-half the value for [NiO]2, yet the adsorp-tion energy is 1.7 times greater. The charge transfer is reckoned to be the governing mechanism underlying this increase.