Mechanism of the Hydrogen Gas Diffusion Electrode

Equations were formulated for the electrolyte film mechanism, in which H 2 diffuses through a film of electrolyte covering the surface of the pores in the electrode. The polarization characteristics at high and low currents were obtained analytically. The equations were solved numerically on a computer using data for H 2 on Ni with an NaOH electrolyte for various values of the surface roughness, pore radius and length, temperature, concentration of electrolyte, and film thickness. A similar computer solution was made of Justi's equations for the surface diffusion mechanism, and the results of the two calculations were compared. The results show that the electrolyte film mechanism has a maximum current 300 times larger, and a slope of the polarization curve at low currents, which is 45 times less than that for the surface diffusion mechanism.