Reversible Hydrogen Storage by Planar Hypercoordinate Carbon Clusters

Abstract

Planar hypercoordinate carbon clusters show a high capacity of hydrogen storage with better stability, as revealed by using density functional theory. The interaction energy of H2 with the cluster lies in between chemisorption and physisorption (0.11–0.19 eV). Topological analysis indicates closed shell-type interaction of H2 with the clusters. The clusters remain stable before and after adsorption. The gravimetric densities are found to be 25.6, 39.7, and 13.5 wt % for planar tetracoordinate, pentacoordinate, and hexacoordinate clusters, respectively. Furthermore, Born–Oppenheimer molecular dynamics simulations indicate the reversibility of adsorption. The clusters can accommodate a large number of H2 molecules and can be released at an elevated temperature (400 K). Our computation reveals that the planar clusters may be used as ideal 2D materials for energy storage.