Achieving 2400+ Hours Pure Water‐Fed Electrolysis via Hydroxide Exchange Membrane‐Electrodes Interface Engineering

Abstract Pure water‐fed hydroxide exchange membrane water electrolysis (HEMEL) offers cost and corrosion advantages but faces challenges in performance and durability. Here, a breakthrough is presented through hydroxide exchange membrane‐electrode interface engineering, achieving exceptional efficiency and long‐term stability in pure water‐fed HEMEL. This involves a novel a poly (ether‐ether‐ketone) (PEEK) reinforced hydroxide exchange membrane (HEM) featuring low glass‐transition temperature (T g ) materials on both sides, enabling excellent adhesion between HEMs and electrodes via a hot‐press process. This achieves an outstanding HEM/anode bonding strength of 23.5 N mm −1 , two orders of magnitude higher than that of a typical poly (aryl piperidinium) HEM/anode. The optimized electrolyzer demonstrates a current density of 1200 mA cm −2 at 1.8 V, alongside unprecedented durability with continuous operation for 2464 h at 500 mA cm −2 , showing the longest durability record to date for pure water‐fed HEMEL. Postmortem membrane‐electrode‐assembly analysis reveals that HEM degradation and cathode structural changes are the primary causes of performance decay. Furthermore, scalability is validated using a large‐scale 160 cm 2 cell, which achieves stable operation for 160 h at 200 mA cm −2 . This work marks a critical milestone toward the industrial implementation of high‐performance, durable HEMEL technology for green hydrogen production.