Movement of hydrogen molecules in pristine, hydrogenated and nitrogen-doped single-walled carbon nanotubes

Carbon nanotubes (CNT) are considered promising nano-scale materials because of their unique structural, mechanical and electronic properties. Due to their long seamless cylindrical shaped structures they could be applied as effective nano-channels for mass transfer and relevant storages for hydrogen molecules. We study hydrogen transport mechanisms in CNTs for various chiral indices and different peculiarities, using the molecular dynamics simulation and quantum mechanical approach. Various CNT models such as pristine, hydrogenated and doped by nitrogen atoms of zigzag (10,0), chiral (7,5) and armchair (6,6) types with hydrogen molecules diffusing inside are simulated at 300 K. The behaviour of hydrogen molecules inside CNTs is analysed using mean-square displacements and velocity autocorrelation functions. From the quantum mechanical approach, the electronic density distribution of CNT is calculated to verify the smooth characteristics of inner surfaces of nanotubes.