High‐Efficiency Anion Exchange Membrane Water Electrolysis Employing Non‐Noble Metal Catalysts

Abstract Alkaline anion exchange membrane (AEM) water electrolysis is a promising technology for producing hydrogen using renewable energies. However, current AEM electrolyzers still employ noble‐metal‐containing electrocatalysts, or have significant overpotential loss, or both. Here non‐noble‐metal electrocatalysts for both the hydrogen and oxygen evolution reactions (HER and OER) are developed. Both catalysts are made of a same NiMo oxide. Judicious processing of these materials in a mixed NH 3 /H 2 atmosphere results in a NiMo‐NH 3 /H 2 catalyst, which has superior activity in HER, delivering 500 mA cm −2 at an overpotential of 107 mV. Doping Fe ions into the NiMo‐NH 3 /H 2 catalyst yields an Fe‐NiMo‐NH 3 /H 2 catalyst, which is highly active for the OER, delivering 500 mA cm −2 at an overpotential of 244 mV. These catalysts are integrated into an AEM electrolyzer, which delivers 1.0 A cm −2 at 1.57 V at 80 °C in 1 m KOH. The energy conversion efficiency at this current density is as high as 75%. This work demonstrates high‐efficiency AEM electrolysis using earth‐abundant catalytic materials.