Exploring the potential of alkali metal-decorated TPH-Graphene nanoribbons for high-efficiency hydrogen storage: A first-principles study

One-dimensional (1D) Tetra-Penta-Hepta graphene nanoribbon (TPH-GNR) is an enticing material because of its distinctive structural and electrical characteristics. Using first -principles calculations, we investigate hydrogen molecules (H-2) storage on alkali metal (M = Li and Na)-decorated TPH-GNR. The initial results indicate that the adsorption of H-2 on pristine TPH-GNR is weak (-0.09 eV/H-2). However, alkali metal decoration significantly enhances the adsorption strength. Ab initio molecular dynamics simulations confirm the thermal stability of alkali metal -decorated TPH-GNR. We further analyze the charge transfer mechanism and density of states, which reveal a strong polarization of the H-2 molecules. Our study also reveals that 4 M@TPH-GNR exhibits gravimetric densities of 7.75 % (Li) and 6.90 % (Na), indicating the potential of TPH-GNR as an effective substrate for H-2 storage. Furthermore, a thermodynamic evaluation is conducted to examine the absorption and release of H-2 under practical operating conditions. Our findings suggest that alkali metal-decorated TPH-GNR can serve as a prospective material for efficient H-2 storage.