抄録
Hydrogen evolution overpotential of the cobalt plated cathode in a 3.0mol/dm3 NaOH solution at 80°C was studied by comparing polarization curves. For a 20A/dm2 plating current density with 3.0mol/dm3 urea added to the cobalt citrate plating bath, a low hydrogen overpotential value was obtained. The value was same to that of rhodium electrode. Vanadium or molybdenum co-deposited cobalt plating cathode had lower hydrogen overpotential than above mentioned pure cobalt plated cathode. Suitable plating conditions for low hydrogen overpotential cathodes were above 4×10-3 mol/dm3(about 0.8g/dm3) vanadium pentoxide or ammonium molybdate addition and above 30A/dm2 plating current densities. Value of overpotential at 25A/dm2 current density was 0.1V. This is a comparable value with that of platinized platinum cathode.
