Achieving High-Efficient and Reversible Hydrogen Storage of the Sun-Graphyne Monolayers Near Room Temperature by Charge Modulation.

To address the critical demand for high-performance hydrogen storage materials in the hydrogen economy, we systematically investigate the structural, electronic, and hydrogen storage performance of pure and charge-modulated Sun-graphyne (SGY) monolayers using first-principles calculations based on the PBEsol functional within Grimme DFT-D2 dispersion correction. Although the SGY monolayer has a high hydrogen storage capacity of 14.3 wt %, the weak physisorption of H2 hinders the SGY monolayer for practical applications. The injected charges can significantly affect the electronic properties of the SGY monolayer. Moreover, the negatively charged SGY monolayer is energetically and thermodynamically stable for potential applications. When 5e- (e represents the elementary charge) charge was applied to the monolayer, an increased average adsorption energy of 0.224 eV for H2 adsorption was determined, while the capacity remains 14.3 wt %. Furthermore, based on the Langmuir thermodynamic model, the influence of realistic temperature and pressure on the adsorption behaviors of H2 molecules was evaluated. The desorption temperature and grand canonical partition function reveal that the effective hydrogen storage capacity maintains a high amount of 12.1-14.1 wt % at the practical conditions of 298.15 K and 10-100 atm, which satisfies the prerequisite condition for solid-state hydrogen storage applications. Our results demonstrate that the charged SGY monolayer exhibits promising potential as a competitive and reversible hydrogen storage media under real-world conditions.