Drop detachment and motion on fuel cell electrode materials

Eric Gauthier, Thomas Hellstern, Ioannis G. Kevrekidis, Jay Benziger

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

Liquid water is pushed through flow channels of fuel cells, where one surface is a porous carbon electrode made up of carbon fibers. Water drops grow on the fibrous carbon surface in the gas flow channel. The drops adhere to the superficial fiber surfaces but exhibit little penetration into the voids between the fibers. The fibrous surfaces are hydrophobic, but there is a substantial threshold force necessary to initiate water drop motion. Once the water drops begin to move, however, the adhesive force decreases and drops move with minimal friction, similar to motion on superhydrophobic materials. We report here studies of water wetting and water drop motion on typical porous carbon materials (carbon paper and carbon cloth) employed in fuel cells. The static coefficient of friction on these textured surfaces is comparable to that for smooth Teflon. But the dynamic coefficient of friction is several orders of magnitude smaller on the textured surfaces than on smooth Teflon. Carbon cloth displays a much smaller static contact angle hysteresis than carbon paper due to its two-scale roughness. The dynamic contact angle hysteresis for carbon paper is greatly reduced compared to the static contact angle hysteresis. Enhanced dynamic hydrophobicity is suggested to result from the extent to which a dynamic contact line can track topological heterogeneities of the liquid/solid interface.

Original languageEnglish (US)
Pages (from-to)761-771
Number of pages11
JournalACS Applied Materials and Interfaces
Volume4
Issue number2
DOIs
StatePublished - Feb 22 2012

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

Keywords

  • Teflon
  • carbon
  • carbon fibers
  • contact angle
  • contact angle hysteresis
  • hydrophobic
  • wetting

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    Gauthier, E., Hellstern, T., Kevrekidis, I. G., & Benziger, J. (2012). Drop detachment and motion on fuel cell electrode materials. ACS Applied Materials and Interfaces, 4(2), 761-771. https://doi.org/10.1021/am201408t