Hexagonal boron nitride ([formula omitted]-BN) nanosheet as a potential hydrogen adsorption material: A density functional theory (DFT) study

Abstract

The hydrogen storage capacity of Boron Nitride nanosheet has been performed by using density functional theory (DFT). All the structural and electronic properties of a monolayer BN nanosheet are in well agreement with the previously reported results. Out of the four possible adsorption sites, centre is the most favourable adsorption site for H2 molecule with binding energy ∼0.212 eV/H2. We have proceeded our calculations considering this adsorption site. The calculated direct band gap within GGA and HSE for pristine h-BN monolayer are found to be 4.669 eV and 5.63 eV, respectively. In our calculation the Hydrogen storage capacity of BN nanosheet was found to be 6.7 wt.% well within benchmark value (6.0%) with an average adsorption energy of (∼0.128 eV/H2). Bader analysis revealed that the charge transfer from BN nanosheet to the H2 molecule is very low (0.004–0.065∣ e ∣) leading to weak binding of the H2 molecule. The calculated desorption temperature was found to be low due to low average adsorption energy of the H2 molecule. Also, upon increasing the number of H2 molecule adsorption a feeble tuning of the band gap has been observed due to the contribution of the 1s orbital of H2 molecule.