In-Situ Ionomer-Free Catalyst-Coated Membranes for Anion Exchange Membrane Water Electrolyzers

Developing a state-of-the-art anion exchange membrane water electrolyzer (AEMWE) for commercial H2 production remains a great challenge and is strongly dependent on the membrane electrode assembly (MEA). Herein, we report the first facile in-situ, ionomer-free catalyst-coated membrane (modified CCM; m-CCM) fabrication method that can apply to a variety of anion exchange membranes (AEMs). This novel m-CCM method allows for the synthesis and integration of a catalyst layer (CL) between the AEM and the gas diffusion layer without anion exchange ionomers. The AEMWE fabricated by the m-CCM method using a platinum group metal-free benchmark anode catalyst exhibited superior performance compared to AEMWEs assembled by the conventional MEA fabrication methods by reducing the interfacial resistance due to the intimate contact and maximizing the catalyst utilization and demonstrated an industrially relevant current density of 1 A cm–2 at a moderate cell voltage of 1.79 Vcell and durability over 200 h in continuous electrolysis at 50 °C in 1 M KOH electrolyte. In addition, it shows the current density of 500 mA cm–2 at a cell voltage of 1.913 Vcell and a low degradation rate of 0.58 mV h–1 for 260 h in continuous electrolysis at a current density of 250 mA cm–2 at 50 °C in feeding ultrapure water.