Unraveling the impact of reverse currents on electrode stability in anion exchange membrane water electrolysis

Anion Exchange Membrane Water Electrolysis (AEMWE) stands out as one of the promising ways of producing green hydrogen. However, significant strides in performance and durability are necessary for commercial competitiveness. Shunt currents and reverse currents are common problems associated with electrolyzers using conductive liquid electrolytes during start/stop conditions and can enhance electrode degradation. This study incorporates a dual Pt-wire reference electrode within the flow cell consisting of a NiFe-layered double hydroxide anode and different cathode materials to decouple individual electrode kinetics under steady state and intermittent operating conditions. The performance of bimetallic cathode catalysts like PtRu/C and NiMo/C was assessed in comparison with traditional Pt/C catalysts in the context of the hydrogen evolution reaction. The initial observed catalyst activity displayed an evident trend in the order of PtRu/C > Pt/C > NiMo/C. When subjected to reverse currents, all three systems showed degradation in performance. The use of reference electrodes illustrated that all cathode coatings degraded as a result of the reverse currents while the anode remained relatively stable. The degradation followed the trend of NiMo/C > PtRu/C > Pt/C. This work thus shows that reverse currents are a real issue for AEMWE and demonstrates the importance of investigating electrodes under intermittent conditions.