This study explores the impact of reverse current on catalyst degradation in alkaline water electrolysis (AWE) systems that are powered by renewable energy sources (RESs). AWE is a promising technology for green hydrogen generation, but frequent on/off cycling due to RES intermittency poses challenges, including catalyst degradation. This research focuses on two key electrocatalysts: Ru for the hydrogen evolution reaction and LaNiO3 for the oxygen evolution reaction. The stability of the catalysts was investigated under dynamic operating conditions. The experiments reveal that the redox capacitance is discharged under closed-circuit conditions, which generates a substantial shift of the applied potential in the reverse direction in both the cathode and anode. As a result, reverse current flows and affects the catalyst stability. The Ru cathode degradation was studied with anodes of varying double-layer capacitance (Cdl). Porous NiRu cathodes with higher Cdl values showed better balance with LaNiO3 anode, which reduced the changes in the resultant reaching electrode potential and thus mitigated degradation due to dissolution of Ru species. This study provides valuable insights for the design of stable electrode materials for AWE systems that operate under fluctuating conditions and emphasizes the importance of tuning the anode–cathode capacitance ratios to enhance durability and efficiency.
Gankhuyag et al. (Thu,) studied this question.
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