DESORPTION BEHAVIOR OF GASEOUS MOLECULES ON SINGLE-WALLED CARBON NANOTUBE BUNDLES

Temperature programmed desorption (TPD) technology was used to examine desorption activation energies (E-d) of O-2, N-2 and Ar on single-walled carbon nanotube (SWCNT) bundles. The SWCNT bundles obtained from Carbon Nanotechnologies Inc. were prepared by high-pressure CO (HiPco) disproportionation process, and had diameters of approximately 0.8 nm. The results show that the temperatures at which the maximum desorption rates of O-2, N-2 and Ar on SWCNTs are all below 200 degrees C, and the corresponding E-d values are 209, 192 and 188 meV, respectively. The E-d values are very close to the isosteric heat of adsorption (q(st)) obtained from our previous studies, implying that these gases are physisorbed onto SWCNTs.