Sr1−xCaxMoO3–Gd0.2Ce0.8O1.9 as the anode in solid oxide fuel cells : effects of Mo precipitation

• Main Authors: Xiao, Peng, Ge, Xiaoming, Liu, Zhaolin, Wang, Jing-Yuan, Wang, Xin
• Other Authors: School of Chemical and Biomedical Engineering
• Format: Article
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering::Chemical engineering
• Online Access: https://hdl.handle.net/10356/103914; http://hdl.handle.net/10220/19371
• Institution: Nanyang Technological University

Calcium is incorporated into strontium molybdate to form Sr1-xCaxMoO3 as an electronic conductor for solid oxide fuel cells (SOFCs). Metallic molybdenum was observed with the increasing content of Ca substitution for Sr in Sr1-xCaxMoO3. Rietveld refinement reveals the phase transition from cubic to tetragonal perovskite structure, which implies its decreased thermodynamic stability under reducing conditions with increasing content of Ca. X-ray diffraction (XRD) and differential scanning calorimetry-thermo-gravimetric analysis (DSC-TGA) further prove that this Mo ex-solution is reversible. The electrochemical performances of Sr1-xCaxMoO3 towards H2 and CH4 oxidation at 800 ºC are examined. The performance is improved in H2 atmosphere with the introduction of Ca, 330 mW cm-2 of Sr0.5Ca0.5MoO3–Gd0.2Ce0.8O1.9 (GDC) vs. 280 mW cm-2 of SrMoO3–GDC, which can be ascribed to the segregated Mo as the additional catalyst. However, carbon deposition is observed after exposure to CH4 at 800 ºC for both Sr0.7Ca0.3MoO3‒GDC and Sr0.5Ca0.5MoO3‒GDC, in contrast to the absence of carbon on SrMoO3‒GDC.