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 Sm3Fe5O32 (SFO) doped by rare earth (Yb, La) metal ions to form Sm3-0.5Yb0.5Fe5O32 (SYFO) and Sm3-0.5La0.5Fe5O32 (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 Omega-cm(2) to 0.45 Omega-cm(2) and the power output improve from 310 mW/cm(2) to 650 mW/cm(2) at 550 degrees 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 degrees C temperature. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Rare earth element doping enhances electrical and electrochemical properties of materials, as demonstrated by the synthesis and application of Sm3Fe5O32 doped with Yb and La in LT-SOFC electrolyte membranes. The doped materials exhibited triple charge transport carriers, promoting HOR and ORR in SOFC. This led to improved power output and reduced polarization resistance compared to undoped electrolytes. The semiconducting nature and protonic conduction of the membranes were confirmed through UV-vis spectroscopy and fuel cell performance tests.