A DFT study of the enhanced hydrogen storage performance of the Li-decorated graphene nanoribbons

The hydrogen storage performances of the pure graphene nanoribbon and the Li-decorated one were studied through the first-principle density functional theory. The results showed that the decorated Li atom could be chemisorbed on the hollow center of the C hexagon with the highness and the adsorption energy of 1.730 angstrom and -0.807 eV, respectively. The hydrogen molecule was found to be weakly physisorbed on the pure graphene nanoribbon but be strongly chemisorbed on the Li-decorated one with the high adsorption energy of -0.263 eV. The further calculation revealed that there were at most four hydrogen molecules stably chemisorbed and stored on the Li atom in the decorated graphene nanoribbon with the average adsorption energy of -0.235 eV. The number of the hydrogen molecules stored on the graphene nanoribbon could be successfully improved to eight through decorating it with two Li atoms on its two sides. Our results indicated that the graphene nanoribbon decorated with Li atoms could be a promising and excellent material to store hydrogen molecules, further implying that it is an effective strategy to enhance the hydrogen storage performance of graphene nanoribbon-based materials through modifying them with metal atoms.