Accelerated Proton Transfer Channel for Breaking the Bottlenecks of Activity and Stability at Industrial‐Scale Anion Exchange Membrane Water Electrolysis

Abstract

ABSTRACT Nickel‐iron‐based oxides are promising alkaline oxygen evolution reaction (OER) electrocatalysts, yet their practical implementation in anion exchange membrane (AEM) water electrolysis remains challenging for large‐area membrane‐electrode assembly (MEA) and stability due to complex synthesis and metal leaching issues. Herein, a scalable NiFeV 0.5 O electrocatalyst achieves the single‐batch production of tens of grams and facilitates the fabrication of a 100 cm 2 MEA using the catalyst‐coated membrane (CCM) approach. Using various in situ characterization methods, we track the OER intermediates and identify the dynamic leaching and readsorption of VO x − species. We pioneer an operando rotating ring‐disk electrode (RRDE) methodology with IrO x pH‐sensing probes, which maps the interfacial acidity and demonstrates that these species elevate the local pH by 1.8 units via a hydrogen‐bond‐accelerated proton transfer channel. Experimental and computational analyses reveal that the readsorbed VO x − species are anchored via directional Fe─O─V bonds, suppressing Fe leaching by eight‐fold compared to conventional NiFeO. Notably, when the gram‐scale synthesized NiFeV 0.5 O is applied as an anode catalyst in a practical AEM water electrolyzer, it delivers 3.0 A cm −2 at a cell voltage of 1.88 V and exhibits remarkable stability at 1 A cm −2 over 500 h with a low decay rate of 0.12 mV h −1 .