Reversible hydrogen adsorption in Ti‐functionalized porous holey graphyne: Insights from first‐principles calculation

Abstract

AbstractBy performing the density functional theory simulations, we have studied the H2 adsorption and desorption properties of the Ti‐functionalized holey graphyne system. The simulation results revealed that the Ti atom is bonded strongly to the holey graphyne sheet with a binding energy of −4.16 eV through the Dewar interaction. The Ti‐functionalized holey graphyne can capture 7H2 molecules with an average H2 adsorption energy of −0.38 eV/H2, leading to a hydrogen gravimetric density of 10.52 wt%. The average desorption temperature is computed by the Van't Hoff relation and obtained to be 486 K, optimum for practical applications. The adsorbed H2 molecules are attached with the Ti‐functionalized holey graphyne via the Kubas interactions involving charge donation and back donation between Ti‐3d orbitals and H‐1 s orbital. Subsequently, the ab initio molecular dynamics simulations have been conducted to verify the structural constancy of the storage media. We have found a sufficiently high energy barrier of 2.3 eV that prevents the system from metal‐metal clustering. Therefore, the Ti‐functionalized holey graphyne can be utilized as a promising high‐capacity reversible hydrogen storage medium.