Tuning ORR electrocatalytic functionalities in CGFO-GDC composite cathode for low-temperature solid oxide fuel cells

Abstract

Mixed ionic and electronic conduction (MIEC) in the composite cathode can alter oxygen stoichiometry and other physiochemical properties, eventually promoting the electrocatalytic functionalities for oxygen reduction reaction (ORR) at low operational temperatures (<650 °C). Here, we demonstrate a composite cathode of CoGd0.8Fe1.80O4 /Gd0.10Ce0.9O2−δ (CGFO-GDC), which delivers low electrode polarization resistance of 0.60 Ω cm2 at 550 °C. The best-performing sample CGFO-GDC exhbits the peak power density (PPD) of 611-343 mW cm−2 at 550-470 °C under a fuel cell conditions. Moreover, durability measurement verifies CGFO-GDC as a chemically stable cathode with improved ORR catalytic functionality. Additionally, first principle calculations using density function theory (DFT) were also conducted to analyze the ion diffusion mechanism of fabricated CGFO-GDC cathode. Our findings certify that introducing ionic conducting GDC into CGFO sample improves the catalytic functionalities. As a result, the composite CGFO-GDC based SOFC delivers minimum electrode polarization resistance with improved power output owing to its enhanced oxygen vacancies and fast catalytic reactions at 550 °C.