Impact of Electrolyte Feeding Strategy on Bubble Dynamics and Performance in Anion Exchange Membrane Water Electrolyzers

Abstract Electrolyte feeding strategy critically influences hydrogen production performance of anion exchange membrane water electrolyzers (AEMWEs), yet the mechanistic influence of electrolyte feeding strategy on bubble transport inside the electrolyzer remains unclear. In this work, an optical bubble visualization platform was employed to compare bubble evolution under anode-feeding and cathode-feeding strategies, revealing totally different bubble evolution phenomena. The anode-feeding strategy promotes oxygen bubble departure at diameters below 200 μm, dominated by the internal bubble growth and departure mode, which presents low transport resistance. In contrast, the cathode feeding strategy limits hydrogen bubble adhering onto the electrode at diameters above 1 mm, dominated by bubble wicking and gas filled modes, leading to severe bubble transport issues. This transition in bubble evolution originates from differences in electrode structure, surface wettability, and Marangoni forces. The smoother oxygen bubble transport in the anode fed electrolyzer further reduces mass transport overpotential and enhances hydrogen production performance. These findings clarify how electrolyte feeding strategy affects bubble evolution and provide practical guidance for optimizing AEMWE operation to improve energy efficiency.