Ba-doped LaCoO₃ perovskite as novel bifunctional electrocatalyst for zinc–air batteries

Developing efficient non-noble metal bifunctional cathode catalysts to accelerate the sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is still a major challenge for zinc–air batteries (ZABs). In the present study, a series of La_1−xBa_xCoO₃ (x = 0, 0.05, 0.10, 0.15, 0.20) perovskite-type oxides were prepared via self-propagating high-temperature synthesis and evaluated as the bifunctional electrocatalytic activity for ZABs. Among the samples, La_0.85Ba_0.15CoO₃ showed the best bifunctional catalytic activity, in which the E_onset of ORR at 0.1 mA cm⁻² and the E_j of OER at 10 mA cm⁻² in 0.1 M KOH solution were 0.829 and 1.685 V vs.RHE, respectively. Besides, the La_0.85Ba_0.15CoO₃ catalyst was evaluated as an air electrode for ZABs, displaying a high power density of 116.2 mW cm⁻² at the current density of 233.8 mA cm⁻² and a stable charge–discharge voltage gap of 0.98 V after 1200 cycles, with superior cycling stability over 200 h. Characterization analysis revealed that the enhancement of bifunctional electrocatalytic activity was attributed to the larger specific surface area and increase in oxygen vacancy. Thus, the Ba-doped LaCoO₃ material is a promising bifunctional electrocatalyst for ZABs.