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Description
First-principles calculations based on density functional theory (DFT) have been performed to study the adsorption of molecular H$_2$ on the graphene-like material C$_2$N. The possible adsorption sites on top of bonds, on carbon atom and nitrogen atom and the center of C-C hexagon and the C-N hexagon are considered. The adsorption energies for each site are calculated and are found to be in the physisorption regime. We find that the most favorable site of H$_2$ is above the center of C-N hexagon. In addition, we demonstrate that inclusion of the Van der Waals interactions through the DFT-D2 method via the generalized gradient approximation (GGA) functional gives the consistent trend of H$_2$ adsorption with that obtained via the local-density approximation (LDA) functional. The effects of Van der Waals interactions on the adsorption energies and equilibrium distance between H$_2$ and C$_2$N sheet are discussed.
