High performance anion exchange membrane water electrolysis driven by atomic scale synergy of non-precious high entropy catalysts

Anion exchange membrane water electrolysis is one of the key technologies for production of green hydrogen, and developments of highly efficient and durable electrode catalysts in alkaline media are critical for its practical applications. Atomic scale synergy of high entropy materials empowers highly efficient water electrolysis catalysts. Here, Fe, Co, Ni, Cu, and Mo-based high entropy electrode catalysts, including high entropy alloys (FCNCuM) for cathodes and high entropy oxides (FCNCuMO_X) for anodes, are developed for high-performance Anion exchange membrane water electrolysis. FCNCuMO_X and FCNCuM exhibit outstanding catalytic efficiency toward oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively, achieving ultralow overpotentials of 183 and 294 mV for OER and 38 and 230 mV for HER at 10 and 500 mA cm^-2, respectively, in 1 M KOH. The anion exchange membrane water electrolyzer, using FCNCuMO_X and FCNCuM as the anode and cathode catalysts, respectively, achieves an ultrahigh specific activity of 293 mA mg^-1 and exhibits outstanding durability with decay of only 0.014 % after a 100 h operation at 500 mA cm^-2. In-situ Raman and in-situ X-ray absorption studies disclose that atomic scale synergy between Fe, Co, and Ni, the three main active centers, is responsible for the extraordinary OER activity, and density functional theory calculations reveal that atomic scale synergy between Mo and Ni leads to the outstanding HER performance.