Adsorption Properties of Hydrogen on H-Capped (5, 5) Boron Nitride Nanotube (BNNT) Through Density Functional Theory

The density functional theory (DFT) has been used to simultaneously investigate physic/chemisorption properties of hydrogen on the (5, 5) boron nitride nanotube (BNNT). Geometry optimizations were carried out at B3LYP/6-31G* level of theory using Gaussian 98 suites of program. Physisorption of H outside 2 the BNNT with a vertical orientation to the tube axis above a nitrogen atom is the most stable state of physisorption and its binding energy is very weak, -0.713 kcal/mol. In the chemisorption of two hydrogen atoms, the most stable state is above two adjacent B and N atoms of a hexagon with a B–N bond length of 2.66 Å and the binding energy of adsorbed hydrogen atoms -91.299 kcal/mol. Based on these results, we have also investigated the total electronic properties, HOMO, LUMO and energy gap for the (5, 5) BNNT and BNNT-H2 structures.