Synthesis and characterization of Mo-doped SrFeO3−δ as cathode materials for solid oxide fuel cells

This paper demonstrates the potential application of Mo-doped SrFeO3−δ perovskites as new cathode materials for solid oxide fuel cells (SOFCs). SrFe1−xMoxO3−δ (x = 0, 0.05, 0.1, 0.2 and 0.25) perovskite materials have been synthesized by a microwave-assisted combustion method. By doping with Mo, the electrical conductivity of the doped SrFeO3−δ in air is reduced with increasing amounts of Mo. At 800 °C, the conductivity drops from about 62 to 22 S cm−1 when the doping level is increased to 25%. According to X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR) results, a decrease in the concentration of charge carrier Fe4+ ions may account for the decrease in electrical conductivity. In contrast, the resistance to sintering and tolerance to reduction of SrFeO3−δ are improved by Mo-doping. Additionally, the thermal expansion coefficient at 800 °C drops from 40.8 × 10−6 K−1 for SrFeO3−δ to 25.7 × 10−6 K−1 for SrFe0.8Mo0.2O3−δ and 20.9 × 10−6 K−1 for SrFe0.75Mo0.25O3−δ. This significant decrease in the thermal expansion coefficient makes Mo-doped SrFeO3−δ materials attractive as cathode candidates for SOFCs. Finally, a relatively low polarization resistance of 0.074 Ω cm2 is obtained for SrFe0.8Mo0.2O3−δ at 800 °C in air.

► SrFe1−xMoxO3−δ (0 ≤ x ≤ 0.25) have been synthesized by a combustion method.
► The doping effects of Mo on the properties of the material have been investigated.
► The tolerance to reduction of SrFeO3−δ is improved by doping with Mo.
► Mo-doped SrFeO3−δ shows promising performance as a cathode material for SOFCs.