| dc.description.abstract | There is polarization phenomenon in water electrolysis. The polarization could be separatedinto three parts, namelyconcentration, active, and ohmic polarizations.
The potassium hydroxide electrolyte concentration is set up from 10% to 40%, and the potential is set up from 2V to 3V. Electrode distance is kept at 2mm, 5mm, and 10mm, while the electrode materialis nickel. Then the potentiostat is used to record the data.
Results show that the impedance decreases when theelectricpotential is increased. The optimal result occurs when the electrolyte concentration is 30%. If the concentration is too high or too low, concentration polarization is the main factor. When the concentration is at20% or 30%, active polarization becomes the primary factor.
The overpotentialis usually due to the active polarization on low current, and the concentration polarization is not obvious at this time. When the current reaches the limit current, the concentration polarization becomes the main cause for the overpotential. When applied potential is over 2.5V, there will beoxided layers deposited on the cathode side surface. The best performanceoccurs as the electrode distance is 2mm.
Key word: polarization, water electrolysis, equivalent circuit model, electrochemical impedance spectroscopy. | en_US |