Hydrogen Storage In Single-Walled Carbon Nanotubes Purified By Microwave Digestion Method

The aim of this study was to synthesize the single walled carbon nanotubes (SWCNTs) and determine their hydrogen storage capacities. SWCNTs were firstly synthesized by chemical vapor deposition (CVD) of acetylene (C2H2) on a magnesium oxide (MgO) powder impregnated with an iron nitrate (Fe(NO3)3·9H2O) solution. The synthesis parameters were selected as: the synthesis temperature of 800°C, the iron content in the precursor of 5% and the synthesis time of 30 min. Purification process of SWCNTs was fulfilled by microwave digestion at three different temperatures (120, 150 and 200 °C), three different acid concentrations (0.5, 1 and 1.5 M) and for three different time intervals (15, 30 and 60 min). Nitric acid (HNO3) was used in the removal of the metal catalysts. The hydrogen storage capacities of the purified materials were measured using volumetric method at the liquid nitrogen temperature and gas pressure up to 100 bar. The effects of the purification conditions such as temperature, time and acid concentration on hydrogen adsorption were investigated.

Authors:

• Neslihan Yuca
• Nilgün Karatepe

Keywords:

• Carbon nanotubes
• purification
• microwavedigestion
• hydrogen storage

References:

[1] M.S. Dresselhaus, G. Dresselhaus, P.C. Eklund, D.E.H. Jones, "Science
of Fullerenes and Carbon Nanotubes", Academic Press, San Diego,
1996, pp. 1-985.
[2] M. Chen, H.W. Yu, J.H. Chen, H.S. Koo, "Effect of purification
treatment on adsorption characteristics of carbon nanotubes", Diam
Relat Mater 2007;16:1110-5.
[3] P. Ciambelli, D. Sannino, M. Sarno, C. Leone B. Smith, "Wide
characterisation to compare conventional and highly effective
microwave purification and functionalization of multi-wall carbon
nanotubes", Thin Solid Films 519 (2011) 2121-2131.
[4] Y.J. Chen, M.L.H. Green, J.L. Griffin, J. Hammer, R.M. Lago, S.C.
Tsang. "Purification and opening of carbon nanotubes via bromination",
Adv Mater 1996, 8(12):1012-5.
[5] A.G. Rinzler, J. Liu, H. Dai, P. Nikolaev, C.B. Huffman, F. Rodr─▒guez-
Mac─▒as, "Large-scale purification of single-wall carbon nanotubes:
process, product, and characterization", Appl Phys A1998;67(1):29-37.
[6] Y.H. Wang, H.W. Shan, R.H. Hauge, M. Pasquali, R.E. Smalley, "A
highly selective, one-pot purification method for singlewalled carbon
nanotubes", J Phys Chem B 2007;111(6):1249-52.
[7] X.R. Ye, L.H. Chen, C. Wang, J.F. Aubuchon, I.C. Chen, A.I. Gapin,
"Electrochemical modification of vertically aligned carbon nanotube
arrays", J Phys Chem B 2006;110(26):12938-42.
[8] Y. Wang, L. Gao, J. Sun, Y.Q. Liu, S. Zheng, H. Kajiura, "An integrated
route for purification, cutting and dispersion of single-walled carbon
nanotubes", Chem Phys Lett 2006,;432(1-3):205-8.
[9] H.Z. Geng, T.H. Kim, S.C. Lim, H.K. Jeong, M.H. Jin, Y.W. Jo, Y.H.
Lee, "Hydrogen storage in microwave-treated multi-walled carbon
nanotubes", International Journal of Hydrogen Energy 35, 2010:2073-
2082
[10] S. Curran, D.L. Carroll, P.M. Ajayan, P. Redlich, S. Roth, M. R├╝hle, W.
Blau, "Picking needles from the nanotube-haystack", Advanced
Materials 1998;10(14):1091-3.
[11] H. Athalin, S. Lefrant, "A correlated method for quantifying mixed and
dispersed carbon nanotubes: analysis of the Raman band intensities and
evidence of wavenumber shift". J. Raman Spectrosc. 2005;36: 400-8
[12] W.E. Alvarez, B. Kitiyana, , A. Borgn, , D.E. Resasc, "Synergism of Co
and Mo in the catalytic production of single-wall carbon nanotubes by
decomposition of CO", Carbon 2001;39: 547-58.
[13] H.M. Kingston, S.J. Haswell, "Microwave-Enhanced Chemistry
(Fundamentals, Sample Preparation, and Applications)", American
Chemical Society,Washington,DC, 1997.