Novel B6P6X (X=As, Sb) monolayers for antiferromagnetic spintronics and hydrogen storage

Abstract

Embedding foreign atoms into porous two-dimensional (2D) materials has emerged as a promising strategy to tailor their electronic, magnetic, and adsorption properties, enabling promising applications in energy storage and spintronics devices. In this work, spin-polarized density functional theory (DFT) calculations were employed to investigate the ground state properties and hydrogen (H${}_2$) storage of interstitially X = As and Sb atom doped $B_6{P}_6$ ($B_6{P}_{6}X$) graphenylene monolayers. The resulting $B_6{P}_{6}X$ (X = As, Sb) monolayers exhibit very good mechanical, dynamical, and thermal stabilities with antiferromagnetic (AFM) ground states. Electronic structure calculations reveal AFM semiconducting behavior for both monolayers, with indirect/direct band gaps of 0.71/0.60 eV (PBE) and 2.19/2.14 eV (HSE06) for $B_6{P}_{6}As$/$B_6{P}_{6}Sb$, respectively. All $B_6{P}_{6}X$ monolayers exhibit an in-plane easy magnetization axis. The obtained Berezinskii–Kosterlitz–Thouless transition (BKT) temperature value of $B_6{P}_{6}Sb$ monolayer is 268.74 K. Furthermore, the H${}_2$ storage capabilities of these $B_6{P}_{6}X$ monolayers were examined. We find that $B_6{P}_{6}As$ and $B_6{P}_{6}Sb$ monolayers can each adsorb up to 48H${}_2$ molecules with an average adsorption energy ($E_a$) of -0.14 eV/H${}_2$. The corresponding H${}_2$ storage gravimetric capacities are 6.91 wt% for $B_6{P}_{6}As$@48H${}_2$ and 6.10 wt% for $B_6{P}_{6}As$@48H${}_2$, surpassing the U.S. Department of Energy’s 2025 target of 5.50 wt%. These findings highlighting the potential of $B_6{P}_{6}X$ (X = As, Sb) monolayers for AFM spintronics and H${}_2$ storage applications.