Modified CNTs/Nafion composite: The role of sulfonate groups on the performance of prepared proton exchange methanol fuel cell’s membrane

Document Type : Research Paper


1 Department of Chemical Engineering, Farahan Branch, Islamic Azad University, Farahan, Iran

2 Department of Chemical Engineering, Faculty of Engineering, University of Isfahan, Isfahan, Iran


A novel Nafion®-based nanocomposite membrane was synthesized to be applied as direct methanol fuel cells (DMFCs). Carbon nanotubes (CNTs) were coated with a layer of silica and then reacted by chlorosulfonic acid to produce sulfonate-functionalized silicon dioxide coated carbon nanotubes (CNT@SiO2-SO3H). The functionalized CNTs were then introduced to Nafion®, and subsequently, methanol permeability, proton conductivity, ion exchange capacity (IEC) and water uptake properties of the prepared membranes were investigated. The experimental results showed that the water uptake and IEC of the Nafion®/CNT@SiO2-SO3H (1 wt%) membrane increased in comparison with the recast Nafion®. IEC was enhanced from 0.9 meq/g for the recast Nafion® to 0.946 meq/g for Nafion® /CNT@SiO2-SO3H, which could be attributed to the presence of sulfonate groups on the surface of CNTs. In addition, the proton conductivity of the sulfonate modified CNT/Nafion® composite was enhanced in a wide range of temperatures. Selectivity of the fabricated membrane was found to be more than 8-fold higher than that of recast Nafion® 117, demonstrating the promising potential of the produced membranes for DMFC applications.


  • Functionalization of CNTs by a silica layer and sulfonated groups
  • Improvement of proton conductivity and selectivity of the prepared composite membrane
  • Decreasing the methanol permeability by decreasing the size of the nanochannel
  • Enhancement of water uptake and ion exchange capacity by introducing the sulfonated groups


Main Subjects

[1] X. Li, A. Faghri, Review and advances of direct methanol fuel cells (DMFCs) part I: design, fabrication, and testing with high concentration methanol solutions. J. Power Sources, 226 (2013) 223-240.
[2] S. Peighambardoust, S. Rowshanzamir, M. Amjadi, Review of the proton exchange membranes for fuel cell applications, Int. J. Hydrogen Energ. 35 (2010) 9349-9384.
[3] K.A. Mauritz. R.B. Moore, State of understanding of Nafion, Chem. Rev. 104 (2004) 4535-4586.
[4] M.M. Hasani-Sadrabadi, E. Dashtimoghadam, F.S. Majedi, H. Moaddel, A. Bertsch, P. Renaud, Superacid-doped polybenzimidazole-decorated carbon nanotubes: a novel high-performance proton exchange nanocomposite membrane, Nanoscale, 5 (2013) 11710-11717.
[5] A. Hacquard, Improving and understanding direct methanol fuel cell (DMFC) performance, MSc Thesis, Worcester Polytechnic Institute, 2005.
[6] M.S. Asgari, M. Nikazar, P. Molla-Abbasi, M.M. Hasani-Sadrabadi, Nafion®/histidine functionalized carbon nanotube: High-performance fuel cell membranes, Int. J. Hydrogen Energ. 38 (2013) 5894-5902.
[7] C-S. Wu and H-T. Liao, Study on the preparation and characterization of biodegradable polylactide/multi-walled carbon nanotubes nanocomposites, Polymer, 48 (2007) 4449-4458.
[8] N.H. Jalani, K. Dunn, R. Datta, Synthesis and characterization of Nafion®-MO2 (M= Zr, Si, Ti) nano-composite membranes for higher temperature PEM fuel cells, Electrochim. Acta. 51 (2005) 553-560.
[9] Z-G. Shao, H. Xu, M. Li, I-M. Hsing, Hybrid Nafion-inorganic oxides membrane doped with heteropolyacids for high temperature operation of proton exchange membrane fuel cell, Solid State Ionics, 177 (2006) 779-85.
[10] M. Amjadi, S. Rowshanzamir, S. Peighambardoust, S. Sedghi, Preparation, characterization and cell performance of durable Nafion/SiO2 hybrid membrane for high temperature polymeric fuel cells, J. Power Sources, 210 (2012) 350-357. 
[11] D. Jung, S. Cho, D. Peck, D. Shin, J. Kim, Performance evaluation of a Nafion/silicon oxide hybrid membrane for direct methanol fuel cell, J. Power Sources, 106 (2002) 173-177.
[12] K. Adjemian, S. Lee, S. Srinivasan, J. Benziger, A. Bocarsly, Silicon oxide Nafion composite membranes for proton-exchange membrane fuel cell operation at 80-140 oC, J. Electrochem. Soc. 149 (2002) A256-A261.
[13] H-C. Chien, L-D. Tsai, C-P. Huang, C-y. Kang, J-N. Lin, F-C. Chang, Sulfonated graphene oxide/Nafion composite membranes for high-performance direct methanol fuel cells, Int. J. Hydrogen Energ. 38 (2013) 13792-13801.
[14] J-H. Kim, S-K. Kim, K. Nam, D-W. Kim, Composite proton conducting membranes based on Nafion and sulfonated SiO2 nanoparticles, J. Membrane Sci. 415 (2012) 696-701.
[15] I.D. Rosca, F. Watari, M. Uo, T. Akasaka, Oxidation of multiwalled carbon nanotubes by nitric acid, Carbon, 43 (2005) 3124-3131.
[16] P. Molla-Abbasi, K. Janghorban, M.S. Asgari, A novel heteropolyacid-doped carbon nanotubes /Nafion nanocomposite membrane for high performance proton-exchange methanol fuel cell applications, Iran. Polym. J. 27 (2018) 77-86.
[17] W. Stöber, A. Fink, E. Bohn, Controlled growth of monodisperse silica spheres in the micron size range, J. Colloid Interf. Sci. 26 (1968) 62-69.
[18] Y. Xiong, Z. Zhang, X. Wang, B. Liu, J. Lin, Hydrolysis of cellulose in ionic liquids catalyzed by a magnetically-recoverable solid acid catalyst, Chem. Eng. J. 235 (2014) 349-355.
[19] A. Singhvi, S. Gomathy, P. Gopalan, A. Kulkarni, Effect of aliovalent cation doping on the electrical conductivity of Na2SO4: Role of charge and size of the dopant, J. Solid State Chem. 138 (1998) 183-192.
[20] J-M. Thomassin, J. Kollar, G. Caldarella, A. Germain, R. Jérôme, C. Detrembleur, Beneficial effect of carbon nanotubes on the performances of Nafion membranes in fuel cell applications, J. Membrane Sci. 303 (2007) 252-257.
[21] J. Sun, X. Jiang, A. Siegmund, M.D. Connolly, K.H. Downing, N.P. Balsara, Morphology and proton transport in humidified phosphonated peptoid block copolymers, Macromolecules, 49 (2016) 3083-3090.
Volume 3, Issue 4
December 2017
Pages 211-218
  • Receive Date: 15 December 2017
  • Revise Date: 25 January 2018
  • Accept Date: 01 February 2018
  • First Publish Date: 01 February 2018