Oxidation of Porous Transport Layers in Anion Exchange Membrane Water Electrolysis with Alkaline and Pure Water Feed

In anion-exchange membrane water electrolysis (AEMWE), porous transport layers (PTLs) can also be applied as porous transport electrodes (PTEs), i.e. with no additional catalyst layer between membrane and PTL. Especially in alkaline conditions, PTEs made from stainless steel have shown high activity and durability, rivaling that of systems with dedicated catalyst layers, such as NiFe-hydroxide powder based catalyst layers.[1] The aim of this study is to investigate electrode activation over time, relating surface oxidation and Fe transport to cell voltage increase. Different fiber electrodes are investigated, measuring polarization curves up to 4 Acm-2 and degradation at 1 Acm-2 in 1.0 M KOH at 60 °C. All stainless steel cells show similar degradation profiles, with degradation rates from 200 – 400 µVh-1 in the last 50 h of testing. After disassembly, metal-containing particles are observed in the cathode-membrane interface. SEM-EDX confirms Fe as the highest mass fraction of these particles (e).