A-Site Cation-Ordering Layered Perovskite EuBa(0.5)Sr(0.5)Co(2–x)Fe(x)O(5+δ) as Highly Active and Durable Electrocatalysts for Oxygen Evolution Reaction

[Image: see text] The developments of high-performance and tolerant catalysts may enable more sustainable energy in the future, especially toward water oxidation. Herein, we report A-site cation-ordering layered perovskite EuBa(0.5)Sr(0.5)Co(2–x)Fe(x)O(5+δ) (EBSCFx) (x = 0.2–0.6) electrocatalysts. When evaluated for oxygen evolution reaction (OER) in alkaline media, EuBa(0.5)Sr(0.5)Co(1.6)Fe(0.4)O(5+δ) (EBSCF0.4) exhibits the best catalytic activity among all of these catalysts, as evidenced by the lowest overpotential of 420 mV at a current density of 10 mA cm(–2). Notably, the catalytic activity of EBSCF0.4 is better than that of commercial IrO(2) at the overpotential >460 mV. Furthermore, the EBSCF0.4–20RuO(2) (involving 20 wt % RuO(2)) composite catalyst is developed and gives an overpotential as low as 390 mV at 50 mA cm(–2), which is even superior to commercial RuO(2). For overall water splitting, an electrolysis voltage of merely 1.47 V is achieved at 10 mA cm(–2) in an electrolyzer employing EBSCF0.4–20RuO(2) as bifunctional catalysts, with exceptional durability for 24 h. Such a performance outperforms state-of-the-art IrO(2)∥Pt/C and RuO(2)∥Pt/C couples. According to density functional theory (DFT) calculations, the unique catalytic properties of EBSCF0.4 may benefit from highly active Fe sites with octahedral coordination, and the synergistic effects of Fe and Ru sites in the composite catalyst accelerate the electrochemical water oxidation.