Alkali and alkaline-earth atom-decorated B38 fullerenes and their potential for hydrogen storage

The structural and electronic properties of alkali and alkaline-earth metal (Li, Na, K, Mg, and Ca) atom-decorated B-38 fullerene, as well as their potential for hydrogen storage, are studied using all-electron density functional theory. The metal atoms favor face-capping on top of the center of hexagonal holes of fullerene. Large binding energy prevents alkali and alkaline-earth atoms from clustering on the surface of B-38. Large amounts of positive charges are found on Na, K, and Ca atoms. We find that calcium-coated B-38 is the best candidate for hydrogen storage, with moderate adsorption energy of H-2. One Ca atom can adsorb up to five H-2 molecules, resulting in 20 H-2 molecules that can be stored in Ca-4-B-38 with an average binding energy intermediate of 0.075 and 0.240 eV/H-2. The hydrogen storage capacity reaches up to 6.47 wt.%. Charge-induced dipole interaction is responsible for the high hydrogen storage capacity of Ca-4-B-38. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.