Evaluation of rare earth (Yb, La) doped (Sm3Fe5O12) garnet ferrite membrane for LT-SOFC

Rare earth element doping is a popular methodology for improving the electrical and electrochemical properties of materials. Inspired by this ideology, garnet ferrite material Sm 3 Fe 5 O 12 (SFO) doped by rare earth (Yb, La) metal ions to form Sm 3-0.5 Yb 0.5 Fe 5 O 12 (SYFO) and Sm 3-0.5 La 0·5 Fe 5 O 12 (SLFO). The samples are synthesized by sol gel auto combustion and have been applied as electrolyte membrane for the first time in low temperature solid oxide fuel cell (LT-SOFC). The results indicate that the as-prepared materials have triple charge transport (H + /O −2 /e − ) carrier which promotes the hydrogen oxidation reaction (HOR) and oxygen reduction reactions (ORR) in SOFC at triple phase boundary region (TPB). Electrochemical impedance spectroscopy (EIS) reveals that the polarization resistance of SLFO membrane significantly reduces from 0.92 Ω-cm 2 to 0.45 Ω-cm 2 and the power output improve from 310 mW/cm 2 to 650 mW/cm 2 at 550 °C temperature in comparison with that of SYFO and SFO electrolyte supported cells. UV-vis diffused spectroscopy explains the semiconducting nature of the prepared materials due to the existence of optical bandgap in the semiconductor region. The further investigation also verifies the protonic conduction of SLFO membrane by constructing oxygen ion blocking fuel cell with configuration of Ni-NCAL/BZCY/SLFO/BZCY/Ni-NCAL having 427.94 mW/Cm 2 fuel cell performance with 1.03 OCV at 550 °C temperature.