Abstract
The properties of hydrogen storage on graphene with La decoration are investigated using a first-principles plane-wave pseudopotential method based on the density functional theory in this paper. The clustering problem of La decorated graphene is considered and B doping can solve it effectively in theory. We obtain the stable geometrical configuration of the modified system and the properties of hydrogen storage are excellent. It can absorb up to 6 H2 molecules with an average adsorption energy range of –0.529 to –0.655 eV/H2, which meets the ideal range between the physisorbed and chemisorbed states for hydrogen storage. Furthermore, it is proved that the existence of La atom alters the charge distribution of H2 molecules and graphene sheet based on the calculation and analysis about the electronic density of states and charge density difference of the modified system. La atom interacts with hydrogen molecules through Kubas interaction. Thereby, it improves the performance of graphene sheet for hydrogen storage. The modified system exhibits the excellent potential to become one of the most suitable candidates for hydrogen storage medium at near ambient conditions with molecule state.
Highlights
Due to the high energy density and clean fuel source, hydrogen as a promising alternative energy has attracted great attention all over the world [1] [2]
Similarto other rare earth metal atoms attaching on carbon nanomaterials [41] [42], the favorite adsorption site for an isolated La atom on the surface of graphene is the center of a hexagonal ring
We have performed first-principles electronic structure calculations to study the properties of hydrogen storage on graphene with La decoration
Summary
Due to the high energy density and clean fuel source, hydrogen as a promising alternative energy has attracted great attention all over the world [1] [2]. This range of energy is intermediate between the physisorbed and chemisorbed states It is ideal for hydrogen storage under ambient pressure and temperature. Similar to other carbon nanomaterials, the interaction between graphene and H2 is through weak van der Waals forces with low adsorption energy ~−0.1 eV/H2 at ambient conditions [15]-[17]. It is meaningless for using pristine graphene to store hydrogen. We focus primarily on the stable geometrical configuration of graphene with La decoration, the adsorption of hydrogen and the effects of La for the process of hydrogen storage using a first-principles plane-wave pseudopotential simulations based on the density functional theory in this paper
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