Bi0.7Sr0.3(Fe, Ni)O3-δ perovskite covered by self-assembled dual-phase ferrites as high-performance cathode for intermediate-temperature solid oxide fuel cells

[Display omitted] •Dual-phase ferrites Bi2Fe4O9 and NiFe2O4 are self-assembled on Bi0.7Sr0.3(Fe, Ni)O3-δ cathodes.•Both electronic conductivity and anti-chromium ability are dramatically enhanced.•The single cell yields a maximum power density of 715.89 mW cm−2 at 700 °C. Bi1-xSrxFeO3-δ (BSFO), a novel Co-free perovskite with advantages of low thermal expansion coefficient and good catalytic activity, suffers from poor electronic conductivity and undesirable chromium-poisoning for the application in solid oxide fuel cells (SOFCs). In this paper, high performance Bi0.7Sr0.3(Fe, Ni)O3-δ cathodes modified by self-assembled dual-phase ferrites Bi2Fe4O9 and NiFe2O4 were fabricated by a simple Ni doping method. The comprehensive properties consisting of electronic conductivity, anti-chromium ability, and oxygen reduction reaction (ORR) activity all were dramatically enhanced. The electronic conductivity (2.32 S cm−1 @700 °C) of Ni doped samples is about 1.8 times higher than that of BSFO (1.24 S cm−1@700 °C). The polarization resistance retains nearly no change under the Cr-treatment condition, which is mainly due to higher Cr2O3 adsorption energies by assembled dual-phase ferrites confirmed by the DFT calculation. The optimized polarization resistance (Rp) is 0.19 Ω cm2 at 700 °C, only 25 % of that of BSFO (0.76 Ω cm2 at 700 °C). The single cell with modified cathodes using wet H2 as fuels shows a maximum power density (Pmax) of 715.89 mW cm−2 at 700 °C, and a stable output maintaining for 50 h without evident degradation.