Enhancing Fe–O Covalency for Facilitating Anion Exchange Membrane Water Electrolysis

Abstract

In anion exchange membrane water electrolysis, Fe dissolution from NiFe-layered double hydroxide at high current density severely compromises stability, causing impaired mass transport, bubble accumulation, and active-site degradation. Herein, we rationally construct a 3D hierarchical electrode consisting of polydopamine-modified carbon nanotube-supported NiFe-LDH (P-CNT@NiFe-LDH) in situ grown on a nickel foam. Experimental and density functional theory results reveal that the P-CNT interlayer induces electron redistribution from Ni to Fe sites, enhancing Fe–O covalency via shortened bond length and elevated bond energy, thus stabilizing Fe ions and inhibiting leaching. The interlocked nanosheet-island structure provides abundant active sites and accelerates bubble detachment. In 1 M KOH, the electrode shows an oxygen evolution reaction overpotential of 264.81 mV at 100 mA cm–2. With P-CNT@NiFe-LDH ‖ Pt/C in AEMWE, the cell achieves 1 A cm–2 at 1.70 V, a 2.5-fold current density higher than NiFe-LDH and maintains stable operation over 500 h at 1 A cm–2 with a decay rate of 0.06 mV h–1. In situ electrochemical impedance spectroscopy and high-speed bubble imaging validate fast reaction kinetics and excellent antibubble-blocking behavior. This work demonstrates the synergy of electronic modulation and structural engineering, providing a feasible strategy for high-performance industrial AEMWE anodes.