M. Inaba et al., HYDROGEN OXIDATION ON PARTIALLY IMMERSED NAFION(R)-COATED ELECTRODES, Journal of electroanalytical chemistry [1992], 417(1-2), 1996, pp. 105-111
The mass transport of hydrogen on partially immersed Nafion(R)-coated
electrodes (Nafion(R)\Pt\highly oriented pyrolytic graphite) was inves
tigated as a model of the three-phase region of the gas-diffusion elec
trodes in proton-exchange membrane fuel cells. On raising the electrod
e from a position at which the Nafion(R) coating was fully immersed in
the electrolyte solution (h = 0 mm), the dependence of the H-2 oxidat
ion current on h was similar to that reported for a partially immersed
flat platinum electrode. In contrast, on raising from a partially imm
ersed position (h = 3 mm), the current was independent of h, and highe
r than that when raising from h = 0 mm at a given Nafion(R) thickness.
When raising from h = 3 mm, the Nafion(R) coating above the intrinsic
meniscus was not covered with a thin liquid electrolyte film, but fun
ctioned solely as a supermeniscus. This made hydrogen diffusion easier
, resulting in the observed higher current. From the above results, us
eful implications for the design of gas-diffusion electrodes in PEMFCs
are demonstrated.