Durable Anion Exchange Membrane Water Electrolysis in Low-Alkaline Concentration Electrolyte

Abstract

Anion-exchange-membrane water electrolysis (AEMWE) is a promising technology for scalable green hydrogen production. However, the conventional use of high-alkalinity conditions accelerates membrane degradation, emphasizing the need for low-alkalinity operation to ensure long-term stability. For a low-alkalinity electrolyte with a high water-dissociation energy barrier, Ru serves as an ideal cathodic catalyst owing to its strong Ru–H bond, which provides distinguished water dissociation ability. However, the trade-off is high *H coverage, causing sluggish kinetics and limited durability during high-current operation. Herein, we developed an Ir–Ru solid solution catalyst, which enables rapid hydrogen transfer kinetics through a hydrogen spillover mechanism at high current. As a result, AEMWE with the Ir–Ru solid solution achieved a cell voltage of 1.75 V at 1 A cm^–2 in 0.05 M KOH. Notably, the low-alkalinity AEMWE cell exhibited exceptional durability for over 1000 h, surpassing most of the previously reported data under similar operating conditions. Isotope labeling and in situ characterizations confirmed that dissociated *H spills from efficient water-dissociation sites on Ru to favorable hydrogen-desorption sites on Ir with lower *H coverage, significantly improving activity and stability at high current densities.