Developing robust and highly efficient electrocatalysts for oxygen evolution reaction (OER) is critical for renewable, secure, and emission‐free energy technologies. Perovskite Ba0.5Sr0.5Co0.8Fe0.2O3‐δ (BSCF) has emerged as a promising OER electrocatalyst with desirable intrinsic activity. Inspired by the factor that substituting in transition‐metal sublattice of the perovskite can further optimize the OER activity, herein, nickel‐substituted BSCF is adopted, that is, Ba0.5Sr0.5Co0.8‐xFe0.2NixO3‐δ (x = 0.05, 0.1, 0.2, denoted as BSCFNx, x = 5, 10, 20, respectively), as efficient and stable OER catalysts in alkaline solution. The phase structure, microchemistry, oxygen vacancy, and electrochemical activity of such samples are well‐investigated. Endowed with an overpotential of only 278 mV at 10 mA cm−2 and a Tafel slope of merely 47.98 mV dec−1, BSCFN20 exhibits the optimum OER activity. When constructing a two‐electrode cell with BSCFN20 as anode and Pt/C as cathode (BSCFN20||Pt/C) for water splitting, it only requires a voltage of 1.63 V to achieve 50 mA cm−2, and the BSCFN20||Pt/C remains stable within 80 h at 10 mA cm−2, superior to the state‐of‐the‐art RuO2||Pt/C counterpart. This work provides a feasible strategy for designing stable and highly active perovskite electrocatalysts for future energy storage and conversion.

Nickel substitution contributes to sustained cubic-symmetry perovskite structure and fast oxygen kinetics of Ba0.5Sr0.5Co0.7Fe0.2Ni0.1O3−δ cathode material, enabling superior electrochemical activity and durability for ORR.

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