Doping effects of B and N on hydrogen adsorption in single-walled carbon nanotubes through density functional calculations

The doping effects of B and N on atomic and molecular adsorption of hydrogen in single-walled carbon nanotubes (SWNTs) were investigated through density functional theory (DFT) calculations. The hydrogen adsorption energies and electronic structures were calculated for the pristine and B- or N-doped SWNTs. The B-doping increases the hydrogen atomic adsorption energies both in zigzag and armchair nanotubes. The B-doping forms an electron-deficient six-membered ring structure, and when hydrogen is adsorbed on top of B atom, a coordination-like B-H bond will form. The N-doping forms an electron-rich six-membered ring structure, and decreases the hydrogen atomic adsorption energies in the N-doped SWNT. In case of hydrogen molecular adsorption, both B- and N-doping decrease the adsorption energies in SWNTs.