Three-Dimensional Unified Electrode Design Using a NiFeOOH Catalyst for Superior Performance and Durable Anion-Exchange Membrane Water Electrolyzers

The design of high-performance and durable electrodes for the oxygen evolution reaction (OER) is crucial for anion-exchange membrane water electrolyzers (AEMWE). Herein, a three-dimensional unified electrode in which nickel–iron oxyhydroxide (NiFeOOH) is directly electrodeposited on a gas diffusion layer (GDL) is developed as an AEMWE anode. Unlike conventional electrodes with a separate catalyst layer and GDL, the unified electrode comprises a single component integrating the catalyst layer with the GDL. The resulting unified electrode shows higher catalytic activity than a conventional electrode based on commercial NiFe and IrO2 and stable activity over 500 h. Investigation of the electrode parameters revealed an outstanding AEMWE performance of 3600 mA cm–2 at 1.9 V, which is the highest among many AEMWE studies. The unified AEMWE also showed durable performance at an ultrahigh current density. Therefore, unified electrode design can be considered an alternative to conventional electrodes to reduce the hydrogen production cost.