Hydrogen storage on cation-decorated biphenylene carbon and nitrogenated holey graphene

Abstract

Hydrogen storage on cation-decorated biphenylene carbon (BPC) and nitrogenated holey graphene (C2N) layered materials are addressed by dispersion-corrected density functional theory calculations. Maximum storage capacity and adsorption energy of a gas-phase H2 monolayer adsorbed on both sides of (Li+, Na+, Mg2+, Ca2+)-doped layers are investigated. We find that cations distribute homogeneously on BPC and C2N with a maximum densities of 1.9 and 1.7 ion/nm2, respectively. The H2 adsorption on cation-decorated BPC shows binding energies that vary from −0.14 to −0.26 eV/H2, depending on whether the cation is single or double charged, where the storage capacity are calculated to be around 10 wt%. Whereas, for cation-doped C2N, the H2 binding energies vary from −0.11 to −0.31 eV/H2, with storage capacity between 7.3 and 8.8 wt%. Our results suggest that cation-doped C2N is the most stable material, providing both reversibility and high capacity for hydrogen storage at operational conditions.