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

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 Fe³⁺ and V³⁺ 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 IrO₂ 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 IrO₂ and Pt/C catalysts pair.