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The development of cathode materials with high oxygen reduction reaction (ORR) activity and stability in intermediate temperature (IT) environments is a key factor in the commercialization of solid oxide fuel cells (SOFC). In this paper, the ORR activity of the cathode is improved by doping high-valent Sc3+ ions at the B-site of the Sr 0.5 La 0.5 Co 0.8 Cu 0.2-x Sc x O 3–δ (x = 0, 0.02, 0.04), in which Sr 0.5 La 0.5 Co 0.8 Cu 0.18 Sc 0.02 O 3–δ (SLCCS2) shows the best electrochemical performance, and the area-specific resistance of SLCCS2 at 700 °C is only 0.047 Ω cm2, much lower than the 0.087 Ω cm2 of Sr 0.5 La 0.5 Co 0.8 Cu 0.2 O 3–δ (SLCC), and the peak power density of SLCCS2 reached 1.098 W cm−2, which is 1.84 times that of SLCC (0.598 W cm−2). In addition, SLCCS2 effectively reduces the thermal expansion coefficient, improves thermal matching with traditional electrolytes, and overcomes the problem of insufficient long-term SOFC stability caused by the high thermal expansion coefficient of Co-based perovskite to a certain extent. SLCCS2 also exhibits excellent CO 2 tolerance. Considering comprehensively, SLCCS2 is expected to become an IT-SOFC cathode material with development potential. • Sc doping improves the ORR activity of Sr 0.5 La 0.5 Co 0.8 Cu 0.2 O 3–δ. • Sc doping reduces thermal expansion coefficient of Co-based perovskites. • Sr 0.5 La 0.5 Co 0.8 Cu 0.18 Sc 0.02 O 3–δ has excellent CO 2 tolerance. [ABSTRACT FROM AUTHOR]

As a Ruddlesden-Popper (RP) phase solid oxide fuel cell (SOFC) cathode material, Pr 2 NiO 4+δ (PNO) is a critical challenge for SOFC commercialization due to the lack of oxygen vacancies and insufficient redox reaction (ORR) activity. In this paper, various concentrations of La 0.6 Sr 0.4 CoO 3-δ (LSC) nanoparticles are coated on the surface of PNO by an impregnation method, and the ORR kinetics of PNO is found to be improved by constructing a composite cathode with heterointerfaces. The formation of the heterointerface effectively enhances the transfer of interstitial oxygen in the PNO and the oxygen vacancies in LSC, which can promote the conduction of O2− in the cathode and thus improves the ORR activity of the material. When the impregnation concentration of LSC reached C LSC = 0.2 mol L−1, the ORR activity can reach the highest level. At 700 °C, the area-specific resistance of PNO-LSC reaches 0.024 Ω cm2, which is 83.4% lower than that of PNO (0.145 Ω cm2). And the peak power density of PNO-LSC reaches 0.618 W cm−2, which is 1.89 times larger than that of PNO (0.327 W cm−2). Therefore, the construction of composite cathodes with heterointerfaces via impregnation provides an alternative strategy for enhancing the ORR activity of the cathode materials in SOFC. [Display omitted] • Pr 2 NiO 4+δ -La 0.6 Sr 0.4 COO 3-δ cathode is prepared by impregnation method. • The heterointerface promotes the ORR activity of the cathode. • Pr 2 NiO 4+δ -La 0.6 Sr 0.4 COO 3-δ has excellent ORR activity. [ABSTRACT FROM AUTHOR]