| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1281242 | International Journal of Hydrogen Energy | 2014 | 9 Pages |
•Impact of carbonate and bicarbonate ions on the membrane conductivity determined.•Impact of carbonate and bicarbonate ions on electrode reaction kinetics determined.•Results verified in the alkaline water electrolysis cell.•Improved stability of alkaline water electrolysis not confirmed.
In the present study the impact of KOH replacement by a NaHCO3 or Na2CO3 solution on the performance of alkaline water electrolysis and the life-time of an anion-selective polymer electrolyte was assessed. In the first instance, the impact of the electrolyte composition on the kinetics of the electrode reactions was studied. Subsequently the ionic conductivity of the membrane, in the form of individual anions, and the efficiency of the alkaline water electrolysis process were evaluated by means of electrochemical impedance spectroscopy and a laboratory single-cell alkaline water electrolyzer. The anion used was observed to make a significant impact both on the ionic conductivity as well as on the kinetics of the anode reaction, resulting in reduced electrolysis efficiency. A stability test revealed kinetics of chemical degradation of the polymer anion-selective membrane in a Na2CO3 solution similar to those in a KOH environment at 70 °C. An alternative approach of decreasing the temperature to 50 °C prolonged the chemical stability and made less impact on the process efficiency.
