Efficient oxygen evolution reaction in SrCo0.8Fe0.2O3-δ perovskite and surface reconstruction for practical zinc-air batteries

Highlights: • Reconstruction of the surface of SCF catalyst by simple water bath treatment in H₃BO₃ solution. • The formation of surface nanoflowers was caused by the selective dissolution of surface Sr element during H₃BO₃ heat treatment. • The OER performance was enhanced by large specific surface area and the appropriate amount of oxygen vacancies. • The assembled zinc-air battery has high energy density and good charge and discharge stability. Perovskite oxide has attracted wide attention in the field of electrochemistry due to its intrinsic electrocatalytic activity, structural stability and compositional flexibility. Herein, SrCo_0.8Fe_0.2O_3-δ (SCF-0) material is simply heated in a H₃BO₃ solution to form a synthetic catalyst, exhibiting excellent OER activity. The optimized SCF (SCF-0.2) has an overpotential of 287 mV and a Tafel slope of 50 mV dec⁻¹ at a current density of 10 mA cm⁻² (the two items of SCF-0 are 396 mV and 102 mV dec⁻¹). Subsequent material characterization confirmed that, due to the efficient improvement of the surface morphology of the material, the smooth plane generates numerous needle-like nanoflower structures with a size of 30–50 nm, which significantly enhanced the specific surface area of the material, attributed to selective slowly dissolve out of a lot of Sr and a small amount of Fe. In addition to that, the perovskite SCF-0.2 + Pt/C is used as the air cathode in the self-assembled zinc-air battery, which shows excellent peak energy density ~106 mW cm⁻² and charge-discharge cycle life. In particular, this simple surface modification method provides an effective optimization strategy for improving the specific surface area and OER performance of the material.