Stabilizing oxygen evolution in alkaline water electrolysis via oxyanion-mediated surface reconstruction

High-performance anion exchange membrane water electrolyzers (AEMWEs) are essential for sustainable hydrogen production, yet metal dissolution of non-noble CoFe layered double hydroxide (CoFe-LDH) anodes under industrial operating conditions severely limits their practical deployment. Herein, we present an oxyanion engineering strategy to restrain active site dissolution of cobalt‑iron-based anodes. Inductively coupled plasma mass spectrometry confirms that electrolyte-borne sulfate significantly suppresses cobalt and iron leaching, while in-situ electrochemical impedance spectroscopy and Raman measurements demonstrate that the improved stability arises from selective sulfate adsorption at the electrode interface during catalysis. This oxyanion regulation simultaneously preserves structural integrity and elevates intrinsic oxygen evolution reaction activity. A sulfur-containing heterostructured catalyst is further designed to release sulfate in situ via sulfur oxidation under OER conditions, which autonomously inhibits metal loss and validates the proposed interfacial protection mechanism. As a result, the AEMWE assembled with this catalyst delivers a high current density of 400 mA cm^-2 at a low cell voltage, maintaining stable operation for over 80 h. The protective mechanism proves generalizable, as a series of oxyanion species-including selenite, molybdate, and tungstate-exhibit comparable stabilizing and activity-promoting functions. This study establishes a facile and versatile route to advance the long-duration durability of alkaline water electrolysis devices.