High capacity hydrogen storage on zirconium decorated γ-graphyne: A systematic first-principles study

Abstract

In this work, we investigate the hydrogen-storage properties of Zr-decorated γ-graphyne monolayer employing Density Functional Theory (DFT) for green energy storage. We predict that each Zr atom decorated on graphyne sheet (2D) can adsorb up to seven H2 molecules with an average adsorption energy of −0.44 eV/H2, leading to a hydrogen gravimetric density of 7.95 wt%, and desorption temperature of 574 K, particularly suited to fuel-cell applications. Decorated Zr atom strongly attached to graphyne due to charge transfer from Zr to graphyne sheet. Hydrogen molecules adsorb on Zr decorated graphyne due to Kubas type of interactions. The 4.05 eV diffusion energy barrier for the movement of Zr atoms may avoid the metal-metal (Zr–Zr) clustering. The stability of Zr+γ-graphyne is confirmed by performing ab-initio molecular dynamics simulations at room temperature and at estimated average desorption temperature. Hence, our calculations show that Zr functionalized on γ-graphyne could be a promising solid-state hydrogen storage material.