Limitting current density
ilim of oxygen reduction was measured under a thin NaCl solution film. The reciprocal value of the obtained
ilim increased proportionally with an increase in the electrolyte layer thickness δ when the δ ranged from 20μm to 100μm. From the dependency of the
ilim on the δ, the oxygen reduction mechanism under a thin electrolyte film was proposed. In the proposed model, the oxygen reduction consists of three consecutive processes; dissolution of oxygen into the electrolyte film from gas phase, diffusion through the electrolyte film and charge transfer at electrolyte/electrode interface. From the analysis on the basis of the model, the diffusion coefficients of oxygen in the electrolyte film were obtained to be 5.9×10
-9 m
2s
-1 and 6.1×10
-9 m
2s
-1 for 0.5kmol/m
3 and 5.4kmol/m
3 NaCl solution films, respectively, and the rate-determining rates of dissolution at gas/electrolyte interface were determined to be approximately 5Am
-2 and 3Am
-2 for 0.5kmol/m
3 and 5.4kmol/m
3 NaCl solutions, respectively.
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