  We have investigated the hydrogen storage capabilities of scandium decorated
holey graphyne, a recently synthesized carbon allotrope, by applying density
functional theory and molecular dynamics simulations. We have observed that one
unit cell of holey graphyne can adsorb 6 Sc atoms, and each Sc atom can adsorb
up to 5 H$_2$ molecules with an average binding energy and average desorption
temperature of -0.36 eV/H$_2$ and 464 K, respectively. The gravimetric weight
percentage of hydrogen is 9.80 %, which is considerably higher than the
Department of Energy, United-States requirements of 6.5 %. We have found that a
total amount of 1.9e charge transfers from the 3d and 4s orbitals of Sc atom to
the C-2p orbitals of holey graphyne by performing the Bader charge analysis.
Hydrogen molecules are bonded with the scandium atom by Kubas interactions. The
ab-initio molecular dynamics simulations confirm the structural integrity of
scandium decorated holey graphyne system at the high desorption temperatures.
The presence of sufficient diffusion energy barriers for the Sc atom ensure the
avoidance of metal-metal clustering in the system.

Materials Science;Chemical Physics