Electrochemical Leaching of Ni Dopants in IrRu Alloy Electrocatalyst Boosts Overall Water Splitting

Abstract The commercialization of water‐splitting technology strongly relies on the stable and high‐performance electrocatalyst for hydrogen and oxygen evolution reactions (HER‐OER). In this work, the nickel dopants in IrRu alloyed electrocatalyst for acidic water splitting activity are investigated. The incorporation of nickel dopants induces more oxygen atoms coordinating with Ir/Ru facilitating the formation of *OOH species via nucleophilic attack by H 2 O. Additionally, a fast surface reconstruction is achieved due to the electrochemical dissolution of Ni dopants; as a result, more oxygen species are incorporated, evidenced by in situ Raman spectroscopy and electrochemical impedance spectroscopy. Therefore, the mass activity for Ni@IrRu is enhanced by threefold than commercial IrO 2 in acidic OER catalysis. Moreover, the nickel dopants balance the hydrogen binding strength; as a result, only 609 mV overpotential is demanded to reach 1 A cm −2 in acidic HER catalysis. The polymer electrolyte membrane water electrolyzer (PEMWE) test indicates only 1.87 V is required to attain 2 A cm −2 , 160 mV lower than Pt/C‐IrO 2 revealing its potential application in PEMWE.