Valence electronic structure on oxygen reduction reaction kinetics of Cu-doped Ba0.5Sr0.5FeO3−δ for IT-SOFCs

• Published in: Materials letters 2024-10, Vol.372, p.136959, Article 136959
• Main Authors: Lim, Taeheun, Jo, Kanghee, Kim, Yong-Nam, Lee, Heesoo
• Format: Article
• Language: English
• Subjects: Cu-doped Ba0.5Sr0.5FeO3−δ; Local atomic structure; ORR kinetics; Oxygen vacancy; Valence band structure
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2024.136959

•Cu doping increased oxygen vacancies and valence electron concentrations of BSFCx.•A low area specific resistance of 0.084 Ω cm2 at 700 °C was achieved for BSFC0.2.•Cu doping improved the process of surface charge exchange and ion transfer. Ba0.5Sr0.5Fe1-xCuxO3-δ (BSFCx, x = 0–0.2) cathodes were investigated in the relationship between electronic structure and oxygen reduction reaction (ORR) kinetics. Electronic structure analysis revealed that Cu doping increased the oxygen vacancies (δ) from 0.384 (BSF) to 0.638 (BSFC0.2). The valence band maximum (VBM) shifted from 0.68 eV (BSF) to 0.24 eV (BSFC0.2), which implies a lower activation energy for charge transfer to the adsorbed oxygen. The area specific resistance was 0.042 Ω cm2 at 700 °C (BSFC0.2), a reduction of more than 50 % compared to 0.086 Ω cm2 (BSF). For the distribution of relaxation times analysis, BSFC0.2 showed the smallest peak area in medium frequency region, where the charge exchange and ion transfer occur at cathode.