Adsorption of hydrogen atoms onto the exterior wall of carbon nanotubes and their thermodynamics properties

• Published in: International journal of hydrogen energy 2010-05, Vol.35 (10), p.4543-4553
• Main Authors: Ng, T.Y., Ren, Y.X., Liew, K.M.
• Format: Article
• Language: English
• Subjects: Adsorption; Alternative fuels. Production and utilization; Applied sciences; Carbon; Carbon nanotubes; Chemisorption; Energy; Exact sciences and technology; Exteriors; Fuels; Hydrogen; Hydrogen atoms; Hydrogen energy; ONIOM calculations; Thermodynamic properties; Walls
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2010.02.044

In the present work, we present a systematic analysis of the chemisorption process pathway of hydrogen atoms onto the exterior wall of (5,5) carbon nanotubes using the ONIOM2 (B3LYP(6–31+G(d,p):UFF)) scheme, and we avoid the gross assumption of fixing any of the carbon atoms during the simulation. It is shown that the adsorption of hydrogen atoms onto the sidewall of CNTs are energetically favorable and the most stable state is to form two H–C σ-bonds while the original σ-bond between the carbon atoms is totally severed. In particular, we examined the molecular thermodynamics properties for the reaction at a range of temperatures from 77 K to 1000 K, and the results suggests that the reaction is possible at ambient temperature, but it is less favorable than that at lower temperatures.