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Co-free La 0.6 Sr 0.4 FeO 3-δ (LSFNb 0) and La 0.6 Sr 0.4 Fe 0.9 Nb 0.1 O 3-δ (LSFNb 0.1) perovskite oxides were prepared by a standard solid-state reaction method. The structural stability and electrochemical performance of La 0.6 Sr 0.4 Fe 0.9 Nb 0.1 O 3-δ as both cathode and anode were studied. Nb dopant in LSFNb 0 significantly enhances the structural and chemical stability in anode condition. At 800 °C, the polarization resistances (Rp) of LSFNb 0.1 symmetric electrode based on YSZ electrolyte are 0.5 and 0.05 Ω cm2 in H 2 and air, respectively. The peak power densities of LSFNb 0.1 based on LSGM electrolyte-supported SSOFCs are 934 and 707 mW cm−2 at 850 °C in H 2 (3% H 2 O) and dry CO, respectively. Moreover, the symmetric cell exhibits reasonable stability in both H 2 and CO fuel, suggesting that La 0.6 Sr 0.4 Fe 0.9 Nb 0.1 O 3-δ may be a potential symmetric electrode material for hydrogen and carbon monoxide SOFCs. • The substitution of Nb improves the structural stability of La 0.6 Sr 0.4 FeO 3 in H 2. • The polarization resistances of LSFNb symmetric cells are 0.5 and 0.05 Ω cm2 in H 2 and air, respectively. • The peak power densities of LSFNb symmetric cell are 934 and 707 mW cm−2 at 850 °C in H 2 (3% H 2 O) and dry CO, respectively. [ABSTRACT FROM AUTHOR]

Recycling and reusing of exhaust gas from solid oxide fuel cell (SOFC) could enhance the fuel utilization of methane. In the present work, the effects of two main components of exhaust gas, viz. hydrogen and carbon dioxide, on the performance of exhaust gas reforming methane fueled cell were investigated. The cell with Ni/8 mol% Y 2 O 3 doped zirconia (Ni/YSZ) as the anode was exposed to H 2 CO 2 CH 4 atmospheres at 800 °C. DC techniques and impedance spectroscopy was used for characterization. Two kinds of cells with different fuel utilization factors ( U f ) were used in experiments, which represented different relationship of power density/voltage with current density. The results indicated that electrooxidation of H* dominated the electrochemical reaction on the anode of the cell at low U f value, while electrooxidation of C* becomes important at high U f value. In the case of CO 2 H 2 mixtures, CO 2 improved the exchange current density, raised the value of U f , and depressed anodic activation polarization. As for H 2 CH 4 CO 2 system, H 2 , partly replacing CH 4 , reduced the heat loss in dry reforming, improved the exchange current density, raised U f value, and depressed the activation and concentration polarization resistances of Ni/YSZ anode. But it had limited effect on the power density of the cell with high U f value. [ABSTRACT FROM AUTHOR]

La-doped Sr 2-x La x Fe 1.5 Mo 0.5 O 6-δ perovskite oxides are synthesized and used as a symmetric electrode to evaluate the effect of La on the crystal structure, conductivity, and catalytic activity for O 2 reduction and H 2 oxidation reaction. The electronic doping effect dominates the oversize effect in Sr 2-x La x Fe 1.5 Mo 0.5 O 6-δ oxide, resulting in unit cell volume expansion and decreased conductivity in air. In addition, the introduction of La increases the chemical structural stability of Sr 2 Fe 1.5 Mo 0.5 O 6-δ in reducing condition due to the higher La–O bond compared with Sr–O bond, leading to high catalytic activity for the H 2 oxidation reaction. At 800 °C, the R p values of Sr 1.9 La 0.1 Fe 1.5 Mo 0.5 O 6-δ symmetric cell in air and wet H 2 are as low as 0.075 and 0.21 Ω cm2, respectively. Moreover, the peak power densities of 769, 561, 439, and 653 mW cm−2 at 850 °C are obtained when wet H 2 , CO, CH 4, and C 3 H 8 are used as fuels on Sr 1.9 La 0.1 Fe 1.5 Mo 0.5 O 6-δ /LSGM/Sr 1.9 La 0.1 Fe 1.5 Mo 0.5 O 6-δ cell. The symmetric cell also shows excellent stability (>100 h) in wet H 2 /air, implying Sr 1.9 La 0.1 Fe 1.5 Mo 0.5 O 6-δ oxide is a promising symmetric electrode material. [Display omitted] • The substitution of La improves the stability of Sr 2 Fe 1.5 Mo 0.5 O 6-δ in reducing atmosphere. • La enhances the catalytic activity for H 2 oxidization reaction (HOR). • High electrochemical performance is obtained for SLFM symmetric cell under carbon-based fuels. [ABSTRACT FROM AUTHOR]