Materials Engineering in Perovskite for Optimized Oxygen Evolution Electrocatalysis in Alkaline Condition.

Developing robust and highly efficient electrocatalysts for oxygen evolution reaction (OER) is critical for renewable, secure, and emission-free energy technologies. Perovskite Ba0.5 Sr0.5 Co0.8 Fe0.2 O3-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, Ba0.5 Sr0.5 Co0.8- x Fe0.2 Nix O3-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.