Ba0.95La0.05Fe0.8Ni0.2O3−δ perovskite as efficient cathode electrocatalysts for proton-conducting solid oxide fuel cells

The key issue that limits the electrochemical performance of proton-conducting solid oxide fuel cells (H+-SOFCs) is the sluggish kinetics of the oxygen reduction reaction (ORR) of cathode at intermediate and low temperatures. Herein, oxygen vacancy engineering is conducted on cobalt-free Ba0.95La0.05FeO3−δ (BLF) by nickel substitution, which is confirmed by density functional theory computations. Nickel-substituted BLF material (Ba0.95La0.05Fe1−xNixO3−δ (x = 0, 0.1, 0.2, 0.3)) can promote the generation of oxygen vacancies and improve catalytic activity, which is found to be in line with the experimental results of XPS. The phase structure, microstructure, and electrochemical performance of Ba0.95La0.05Fe0.8Ni0.2O3−δ (BLFNi0.2) are well-investigated. The single cells with the BLFNi0.2-BaCe0.7Zr0.1Y0.1Yb0.1O3−δ (BCZYYb) composite cathode achieve low polarization resistance (Rp) of 0.099 Ω cm2 and a peak power density of 631 mW cm−2 at 700 °C while maintaining good durability for 120 h with no observable degradation. The results demonstrate that Ni-doped BLF is a promising cobalt-free cathode material for H+-SOFCs.