“…5−7 This process consists of two half-reactions, namely, hydrogen evolution reaction (HER) on the cathode and oxygen evolution reaction (OER) on the anode. 6,8 So far, preciousmetal-based electrocatalysts such as Pt/C and RuO 2 have been identified as state-of-the-art materials to drive the reaction and lower the overpotential higher than the theoretical one, 1.23 V. 9,10 Over the past decades, plenty of attempts have been made to design and develop catalysts that alloys, 11−13 carbides, 14,15 nitrides, 16,17 oxides, 18−20 phosphides, 21−23 borides, 24,25 and chalcogenides 26,27 are some of the materials that have been widely explored. Amidst a wide spectrum of electrocatalytic chemicals, the well-known metal compounds of Fe, Co, and Nilocated in the same group with Ru, Ir, and Pt, individually and hence expected to show relatively identical catalytic traits 5 and different compositions of their mixed oxides are believed to have outstanding catalytic activity for electrolysis of water.…”