Modulation of perovskite electronic configuration by cobalt doping for efficient catalysts in zinc-air battery electrodes

An in-depth comprehension of the structural characteristics of perovskite and the response mechanisms is crucial for designing materials with excellent properties. Here, the performance of several kinds of Sr_0.75Pr_0.25Fe_1-xCo_xO_3-δ (x = 0, 0.25, 0.5, 0.75, 1) in an alkaline environment was thoroughly examined. Sr_0.75Pr_0.25Fe_0.25Co_0.75O_3-δ displayed the lowest overpotential (337 mV @ 10 mA·cm⁻²) and Tafel slope (69.3 mV·dec⁻¹) in 0.1 M KOH and possessed excellent performance in zinc-air batteries. Cobalt doping encourages the positive shift of the O 2p band center, boosting the number of electrons around the Fermi energy level and delivering an increase in conductivity, according to DFT and experimental studies. Compared to Sr_0.75Pr_0.25FeO_3-δ, the rate-limiting step of Sr_0.75Pr_0.25Fe_0.25Co_0.75O_3-δ changes from OH*→O* deprotonation to OH* adsorption, which significantly decreases the energy potential barrier during OER process. The A/B site doping method is universal and facile, which is essential to comprehend and develop effective perovskite oxide for zinc-air battery electrodes.