Me–C8B5: A novel two-dimensional carbon boride as reversible hydrogen storage material with high capacity

Abstract

In this work, we predict a new two-dimensional metallic carbon-boron material, named Me–C8B5, which is composed of octagons, pentagons and hexagons. By DFT calculation, we examine the efficacy of hydrogen storage in alkali and alkaline-earth metals modified Me–C8B5 structures. Our findings reveal that these metals exhibit a robust affinity for the Me–C8B5 substrate, characterized by substantial binding energies, thereby mitigating the tendency to form clusters. In particular, the hydrogen storage capacity for Li, Na, Mg and Ca modified Me–C8B5 reach 6.87 wt%, 7.60 wt% and 5.74 wt% and 9.51 wt%, respectively, higher than the DOE requirement of 4.5 wt%. The results of relative energy reveal that the Li-modified system exhibits more appropriate pressure (8.4 bar) and temperature (370 K) for maintaining stable hydrogen storage. Notably, the suitable average desorption temperatures coupled with the stability exhibited in AIMD simulations indicate that Me–C8B5 scaffolds modified with metals Li, Na, Mg, and Ca may possess viable practical applications in the realm of reversible hydrogen storage. These outcomes are anticipated to stimulate the pursuit and continued refinement of novel, superior two-dimensional materials for hydrogen storage.