Direct Regulation of Double Cation Defects at the A1A2 Site for a High-Performance Oxygen Evolution Reaction...

Perovskites are one of the efficient catalysts for the oxygen evolution reaction (OER), and they belong to the primary ABO₃ in which the A site and B site are site-substituted, and oxygen vacancies are introduced. Further improvement of these complex perovskites is the next necessary topic for specific applications. Herein, two complex perovskites, La_0.6Sr_0.4Co_0.8Fe_0.2O_3-δ (LSCF) and Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF), are exploited as the examples to demonstrate the double cation defects-introduced method of A1 and A2 to supply superimposed enhancement of the activity and stability. This is based on the fact that the increased content of oxygen vacancies and coordination can balance the oxygen vacancy and B-site element oxidation state. The electrochemical measurements revealed that the optimized A-LSCF10 and A-BSCF10 both exhibit outstanding OER catalytic activity. A small Tafel slope (57 mV dec^-1) and a low overpotential (228 mV at 10 mA cm^-2) for A-LSCF10 (vs 93 mV dec^-1 and 345 mV at 10 mA cm^-2 for A-LSCF0), and a small Tafel slope (65 mV dec^-1) and an overpotential (242 mV at 10 mA cm^-2) for A-BSCF10 (vs 66 mV dec^-1 and 308 mV at 10 mA cm^-2 for A-BSCF0) are determined, as well as good stability for 24 h.