Defect‐Rich Carbon‐Encapsulated NiMoFe/MoO 2 : A High‐Performance Electrocatalyst for Efficient and Stable Anion Exchange Membrane Electrolysis

Abstract Developing efficient and durable non‐precious metal electrocatalysts for hydrogen evolution reaction (HER) in an alkaline condition is essential for advancing green hydrogen production. Herein, the study reports a defect‐rich NiMoFe/MoO 2 heterostructure encapsulated in a carbon layer (designated as NiMoFe@C‐e) as a highly active and durable HER catalyst. The combined effect of Fe doping, stacking faults defect, and carbon encapsulation endows the catalyst with outstanding HER performance, showing ultralow overpotentials of 27 and 175 mV at 10 and 500 mA cm −2 , respectively, and exceptional stability that sustains operation for 2000 h at 500 mA cm −2 . An anion exchange membrane water electrolysis (AEMWE) single cell (25 cm 2 active area) having an NiMoFe@C‐e cathode and a high‐entropy FeNiCoMnCr layered double hydroxide anode achieves 1 A cm −2 at 1.89 V, and maintains stability for over 1000 h at 500 mA cm −2 with a degradation rate of only 190 µV h −1 . The system delivers a high energy conversion ≈82%, nearly 100% Faradaic efficiency, and low energy consumption (45.5 kWh per kg H 2 ). A two‐stack AEMWE cell further demonstrates the practical viability of the system, sustaining for 800 h at 1 A cm −2 . This work presents a promising pathway toward scalable, cost‐effective alkaline electrolysis using earth‐abundant catalysts.