Abstract
Hydrogen bound via Kubas interaction on metal decorated light weight materials forebodes a much efficient alternative for the fast depleting fossil fuels. However, oxygen interference in hydrogen storage on metal decorated carbonaceous systems obstructs the successful realization of the theoretically promised high storage of Kubas bound H-2. The interference is a consequence of preferred O-2 binding at the metal site, thereby blocking it for H-2 adsorption. Here, we report that arene capping of a Sc-metallacarborane (MCB) efficiently reverses the preferential adsorption of O-2 over H-2. The capped MCB completely repels O-2 off the Sc-site allowing purely Kubas binding of H-2. This is enabled by the down-shift of the d-band center of Sc below the Fermi-level from 1.29 eV in the uncapped to 5.67 eV in the capped MCB, respectively. The optimised d-band center position enables the empty Sc antibonding states to only be available for hydrogen adsorption via Kubas interaction, thereby, to completely avoid oxygen binding. This novel approach tunes a cluster electronically to enhance gas adsorption selectivity, which can be efficiently ulitized in various catalytic, sensing and gas storage systems. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.