A novel lithium decorated N-doped 4,6,8-biphenylene for reversible hydrogen storage: Insights from density functional theory

Abstract

Two-dimensional (2D) carbon-based (C-based) and carbon-nitrogen (C–N) materials have great potential in the energy harvest and storage fields. We investigate a novel carbon biphenylene (C468) consisting of four-, six- and eight-membered rings of sp2 carbon atoms (Fan et al., Science, 372:852-6 (2021)) for hydrogen storage. Using first-principles based Density functional theory calculations, we study the geometrical and electronic properties of C468 and N-doped C468. Lithium (Li) atoms were symmetrically adsorbed on both sides of the substrate, and their adsorption positions were determined. The maximum gravimetric density of hydrogen (H2) adsorbed symmetrically on both sides of Li atom was studied within the scope of physical adsorption process (−0.2 eV/H2 ∼ −0.6 eV/H2). Li-decorated C468 can adsorb 8 upper hydrogen molecules and 8 lower hydrogen molecules, and Li-decorated N-doped C468 can adsorb 9 upper hydrogen molecules and 9 lower hydrogen molecules. The gravimetric densities of Li-decorated C468 and Li-decorated N-doped C468 can reach 9.581 wt% and 10.588 wt%, respectively. Our findings suggest significant insights for using Li-decorated C468 and Li-decorated N-doped C468 as hydrogen storage candidates and effectively expand the application scope of C-based materials and C–N materials.