New trends in the hydrogen energy storage potentials of (8,8) SWCNT and SWBNNT using optical adsorption spectra analysis: a DFT study.

Abstract

We have investigated the hydrogen energy storage potentials of (8, 8) single-walled carbon nanotubes (SWCNTs) and (8, 8) single-walled boron nitride nanotubes (SWBNNTs) using density functional theory. Calculations of the electronic properties of the studied systems were performed using the Perdew, Burke and Ernzerhof (PBE) exchange correlation function of the generalized gradient approximation. The optical adsorption response of the pure and hydrogen-adsorbed systems was determined within G0W0 approximations with both RPA and BSE. From the obtained results, it was found that both (8, 8) SWBNNT and SWCNT were stable when the hydrogen molecule was 8.72 m away from the adsorption surface. SWBNNT was found to show stronger adsorption from 5 to 15 eV, which is in the UV range. On the other hand, SWCNT adsorbs hydrogen in the 0–5 eV which falls in the UV–Vis range, with higher adsorption recorded from 0 to 2.4 eV, which corresponds to the visible range. Although both systems adsorb hydrogen, (8, 8) SWCNT is reported to be better than (8, 8) SWBNNT due to its ability to adsorb in the visible region of the electromagnetic spectrum. Therefore, SWCNT is regarded as a better candidate for hydrogen energy storage under ambient conditions.