Charge modulation-driven high-performance reversible hydrogen storage of Be4C3 monolayers near room temperature: A first-principles study

The hydrogen storage capabilities of the (modulated) Be 4 C 3 monolayers have been systematically investigated using first-principles calculations. The Be 4 C 3 monolayer exhibits high gravimetric capacities of 14.29 wt%, but the H 2 adsorption energy is too weak, which motivates us to explore strain and charge modulations for the monolayer. Strain modulation cannot improve H 2 -adsorption strength. In contrast, charge engineering effectively enhances hydrogen adsorption while maintaining high capacity. The effective gravimetric capacity of charged Be 4 C 3 monolayers reaches 12.08-13.76 wt% at room temperature with pressures ranging from 1 to 30 atm, but it reduces to 0.07 wt% at 373 K and 3 atm when the applied charge is removed, even to 0.24-0.39 wt% at 298.15 K and 1-3 atm, indicating the hydrogen adsorption/desorption on/from Be 4 C 3 monolayer can be effectively regulated by charge modulation. Our results suggest that the charge-modulated Be 4 C 3 monolayers are promising candidates for highly efficient reversible hydrogen storage near room temperature under various pressure conditions.