Enhanced Electrochemical Performance and Membrane Stability of a Hybrid Alkali-Acid Urea Electrolyzer

Bipolar membrane (BPM)-based hybrid acid/alkali electrolyzers represent a notable advancement in the efficient production of hydrogen. However, the degradation behaviors of BPMs within hybrid systems are not well understood. This study introduces the urea oxidation reaction (UOR) as an alternative to the sluggish oxygen evolution reaction at the anode and utilizes X-ray computed tomography to assess the degradation of BPMs. Contrary to the conventional belief that the anion exchange layer is less stable in alkaline environments, it has been discovered that the BPM experiences significant corrosion on the cation exchange layer in hybrid electrolyzers. Using UOR as the anodic reaction not only significantly reduces the overall voltage by ∼300 mV but also effectively mitigates membrane corrosion. These insights into the degradation of BPMs are crucial to the development of more efficient and durable hybrid electrolyzers for hydrogen production.