A‐Site Regulated (PrBa)<i>_x</i>Co_1.5Fe_0.5O_6−δ Double Perovskite Oxides: Highly Active and Durable Electrocatalysts for the Enhanced Oxygen Evolution Reaction

Abstract Oxygen evolution reaction (OER) represents a significant bottleneck in many energy technologies such as electrochemical water splitting, metal‐oxygen (O) batteries, and solid oxide fuel cells (SOFCs) because of the complexity of the reaction process. Double perovskite oxides (ABO 3 ), recognized for their compositional flexibility, have emerged as excellent OER activity and stability. This study investigates the catalytic potential of A‐site‐ordered double ABO 3 with (PrBa) x Co 1.5 Fe 0.5 O 6δ (PBCF − x , x = 0.9–1.1) in alkaline media. The results reveal that PBCF −0.9 , characterized by an A‐site‐deficient composition, exhibits exceptional OER activity. It demonstrates a low Tafel slope of 76.12 mV⋅dec −1 and a low overpotential ( η ) of 270 mV at 10 mA⋅cm −2 . Notably, the intrinsic OER activity of PBCF −0.9 is 25% higher than that of the stoichiometric PBCF −1.0 . Additionally, PBCF −0.9 exhibits remarkable durability, as evidenced by its stable performance during a 6‐h chronopotentiometry (CP) test and minimal microstructural changes. These results underscore the effectiveness of A‐site deficiency in optimizing the structure of double ABO 3 for improved OER performance. This approach presents a promising strategy for designing highly efficient, stable, and inexpensive catalysts for energy‐related applications.