Computational Study of Hydrogen Adsorption on Potassium-Decorated Boron Nitride Nanotubes

We have investigated the potassium-decorated boron nitride nanotubes for hydrogen storage using semi-empirical AM1 method. The ultra narrow (3,3) and (5,0) boron nitride nanotubes of same diameter but of different chirality have been used. Both of them show hydrogen storage greater than 8% by weight. Density of States have been calculated and it is found that the presence of alpha density of state of potassium results in smaller energy gap as a result of which the conductivity of the potassium decorated boron nitride nanotubes is enhanced compared to pristine boron nitride nanotubes. Charge decomposition analysis showed that there is significant transfer of charge from adsorbate potassium to boron nitride nanotubes; the same is also confirmed by Mulliken Population analysis. For the same diameter, due to different electronic configurations, zigzag tube is found to be slightly more favourable for hydrogen adsorption. The results of the present simulation study suggest that the potassium decorated boron nitride nanotubes are good candidates for hydrogen adsorption.