Study of Nitrogen Adsorbed on Single-Walled Carbon Nanotube Bundles

The adsorption of N2 on close-ended single-walled carbon nanotube bundles was studied at different temperatures ranging from 81 to 94 K. The isosteric heat of adsorption was obtained from the adsorption isotherm measurements, and the binding energy of N2 was estimated from the isosteric heat of adsorption data in the low-coverage region. The estimated binding energy was about 86 meV, and this value lies between those of Ne and CH4 on nanotube bundles. It was also observed that the isosteric heat of adsorption increased in regions of low coverage and decreased as the coverage increased. This was due to both interactions between N2 molecules and the heterogeneity of the nanotube bundles.