Borophene/graphene heterostructure for effective hydrogen storage with facile dehydrogenation

A theoretical investigation of the hydrogen adsorption on a β12-borophene monolayer and a β12-borophene/graphene bilayer heterostructure is performed to tailor the substrate properties via functionalization to increase its hydrogen (H₂) physisorption strength and enhance its gravimetric capacity. The results using the density-functional theory show that the H₂ adsorption energy significantly increases as the substrate changes from monolayer to bilayer heterostructure. This enhancement in H₂ adsorption energy is attributed to the synergetic effects of the interlayer interaction in the heterostructure via analysis of the chemical bonding. The lithium decoration of the bilayer heterostructure has indeed increased both the H₂ adsorption energy and gravimetric capacity. Further enhancement of these latter attributes is shown to be plausible to achieve through the application of an electric field normal to the surface and directed upward toward the molecules. The thermodynamic analysis based on the Langmuir adsorption model finds that the high storage capacity should be maintained high with an effective gravimetric capacity of 13.64 wt% at ambient conditions. Our findings demonstrated that the Li-decorated β12-borophene/graphene bilayer heterostructure should be a promising candidate for efficient hydrogen storage applications.