Interferents for hydrogen storage on a graphene sheet decorated with nickel: A DFT study

In the present work, the decoration of a graphene sheet with nickel is considered as a hydrogen storage material by means of density functional theory calculations. A number of factors relevant for the handling and operation of this material were analyzed. This includes the interaction with potentially interfering chemicals, hydride formation and the hydrogen storage capacity. The present results show that unless the access of oxygen to the surface is restricted, its strong bond to the decorated systems will preclude the practical use for hydrogen storage. In the best case, the energy required to replace an adsorbed oxygen molecule by hydrogen is of the order of 1.7 eV, something that indicates the severe problem that the presence of oxygen represents for this type of systems.