A novel Co-free and efficient Pr0.5Ba0.5Fe0.8Cu0.2O3-δ nanofiber cathode material for intermediate temperature solid oxide fuel cells

Abstract

Fe-based perovskite without Co has a low thermal expansion coefficient and can be used as a solid oxide fuel cell (SOFC) cathode to ensure the thermal compatibility with the electrolyte; however, its further advancement is impeded by sluggish oxygen reduction reaction (ORR) dynamics. In this work, the electrospinning method and Cu doping strategy are employed to improve the microstructure and oxygen reduction kinetics of Pr_0.5Ba_0.5FeO_3-δ cathodes. The results show that Pr_0.5Ba_0.5Fe_0.8Cu_0.2O_3-δ has a unique fiber structure and high specific surface area, and the introduction of Cu facilitates the release of lattice oxygen, effectively increasing the oxygen vacancy content. The relaxation time distribution analysis and oxygen reduction reaction dynamics indicate that the oxygen adsorption-dissociation process is the main rate-limiting step in the oxygen reduction reaction of Pr_0.5Ba_0.5Fe_0.8Cu_0.2O_3-δ electrode materials. At 700 °C, the area-specific resistance (ASR) of the symmetric cell of Pr_0.5Ba_0.5Fe_0.8Cu_0.2O_3-δ fiber material is 0.071 Ω cm², and the power density of the single cell reaches 988 mW cm⁻², which shows good electrochemical output performance and long-term operational stability. The preparation of nanofiber cathodes with high specific surface area and porosity by electrospinning provides an effective strategy to enhance the electrocatalytic activity of the IT-SOFC cathode.