Gas molecule adsorption in carbon nanotubes and nanotube bundles

Abstract

We studied various gas molecules (NO 2 , O 2 , NH 3 , N 2 , CO 2 , CH 4 , H 2 O, H 2 , Ar) on single-walled carbon nanotubes (SWNTs) and bundles using first principles methods. The equilibrium position, adsorption energy, charge transfer, and electronic band structures are obtained for different kinds of SWNTs.Most molecules adsorb weakly on SWNTs and can be either charge donor or acceptor to the nanotubes. We find the gas adsorption on the bundle interstitial and groove sties is stronger than that on an individual tube. The electronic properties of SWNTs are sensitive to the adsorption of certain gases such as NO 2 and O 2 . Charge transfer and gas-induced charge fluctuation might significantly affect the transport properties of SWNTs. Our theoretical results are consistent with recent experiments. 73.61.Wp, 73.20.Hb, 34.50.Dy, 82.65.My Typeset using REVT E X 1 16

A qualitative approach to adsorption mechanism identification on microporous carbonaceous surfaces

“…Again, as expected, for SWCNT the lowest values of f ratio were obtained. Those results are consistent with determined experimentally weak adsorption on SWCNT (Zhao et al 2001). Hence, determined values for structure parameter f are in a good agreement with earlier assumed mechanism identification criteria.…”

“…SWCNT material was designed as a model with relatively small expected energetical heterogeneity (at the nanotube cap), resulting in adsorbate condensation not exceeding the critical volume (Zhao et al 2001). Accordingly, the highest minimum value of the potential U m (V mpi ) was obtained for SWCNT (Fig.…”

High electrical conductance enhancement in Au-nanoparticle decorated sparse single-wall carbon nanotube networks

“…The absorption of gaseous species on the surface or inside of a nanotube bundle is stronger than that on an individual SWNT but is reversible [8,9]. Oxygen-exposed networks have p-type characteristics due to transfer of 0.1e -in the charge transfer complex C + -O 2 -  7 ; subsequent adsorption of an electron from donor-like molecules will induce an increase of the resistance and the interaction with acceptor-like molecules will lead to a decrease of the resistance.…”

Density functional study of oxygen adsorption on 4-Å carbon nanotubes

“…On the theoretical side, many calculations and analyses with different levels of sophistication have been reported. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] Some of these studies are focused on the physisorption of O 2 while others consider both physisorption and chemisorption. Various adsorption sites, both inside and outside of SWNT's are discussed and compared with each other and also with graphene.…”