High‐Efficiency Anion‐Exchange Membrane Water Electrolyzer Enabled by Ternary Layered Double Hydroxide Anode

Abstract Developing high‐efficiency and low‐cost oxygen‐evolving electrodes in anion exchange membrane (AEM) water electrolysis technology is one of the major challenges. Herein, it is demonstrated that the surface corrosion of a conventional Ni foam electrode in the presence of Fe 3+ and V 3+ cations can transform it into an electrode with a high catalytic performance for oxygen evolution reaction (OER). The corroded electrode consists of a ternary NiFeV layered double hydroxide (LDH) nanosheet array supported on the Ni foam surface. This NiFeV LDH electrode achieves an OER current density of 100 mA cm −2 at an overpotential of 272 mV in 1 m KOH, outperforming the IrO 2 catalyst by 180 mV. Density functional theory calculations reveal that the unique structure and the presence of vanadium in NiFeV LDH play a key role in achieving improved OER activity. When coupled with a commercial Pt/C cathode catalyst, the resulting AEM water electrolyzer achieves a cell current density as high as 2.1 A cm −2 at a voltage of only 1.8 V cell in 1 m KOH, which is similar to the performance of the proton exchange membrane water electrolyzer obtained from the IrO 2 and Pt/C catalysts pair.