Superalkali functionalized two-dimensional haeckelite monolayers: A novel hydrogen storage architecture

Exploring efficient storage mediums is the key challenge to accomplish a sustainable hydrogen economy. Material-based hydrogen (H-2) storage is safe, economically viable and possesses high gravimetric density. Here, we have designed a novel H-2 storage architecture by decorating graphene-like haeckelite (r57) sheets with the super-alkali (NLi4) clusters, which bonded strongly with the r57. We have performed van der Waals corrected density functional theory (DFT) calculations to study the structural, electronic, energetic, charge transfer, and H-2 storage properties of one-sided (r57-NLi4) and two-sided (r57-2NLi(4)) coverage of r57 sheets. Exceptionally high H-2 storage capacities of 10.74%, and 17.01% have been achieved for r57-NLi4, and r57-2NLi(4) systems, respectively that comfortably surpass the U.S. Department of Energy's (DOE) targets. Under maximum hydrogenation, the average H-2 adsorption energies have been found as -0.32 eV/H-2, which is ideal for reversible H-2 storage applications. We have further studied the effects of mechanical strain to explore the H-2 desorption mechanism. Statistical thermodynamic analysis has been employed to study the H-2 storage mechanism at varied conditions of pressures and temperatures. Our findings validate the potential of r57-xNLi(4) as efficient H-2 storage materials. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.