Dimensionality effects on hydrogen storage performance in MgO-like biphenylene network

Hydrogen is a clean, carbon-free energy carrier, but the development of materials with high hydrogen-storage capacity remains a key challenge. Here, we use density functional theory calculations to design MgO-like biphenylene networks with 1D nanotube, 2D sheet, and 3D porous structures and evaluate their hydrogen-storage properties. All three structures are dynamically stable and exhibit wide band gaps of 4.29–4.82 eV. Hydrogen molecules preferentially adsorb on Mg sites through charge polarization, with adsorption energies of −0.10 to −0.12 eV/H 2 at one H 2 per Mg site. At double loading, the adsorption energy remains near −0.09 eV/H 2 for the 1D and 2D structures but decreases to −0.075 eV/H 2 for the 3D structure due to steric hindrance within the confined pores. All three structures achieve a gravimetric capacity of 9.09 wt%, while the volumetric capacity depends strongly on structural topology, reaching 128.14 g/L for the 1D nanotube. Ab initio molecular dynamics simulations show thermally activated H 2 desorption above 150 K without structural degradation. These results demonstrate that dimensionality engineering can effectively tune hydrogen-storage performance.