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Abstract: The level of barium doping in lanthanum strontium titanate (La0.4Sr0.6−x Ba x TiO3, 0≤ x ≤0.2; LST, x =0; LSBT, x >0), prepared by solid state synthesis, affects its performance as anode in solid oxide fuel cells (SOFCs). Cell structures of LST and all LSBT were similar. The oxidation state of Ti in all compounds was reduced by a comparable amount when LST or LSBT was heated under reducing conditions to form La0.4Sr0.6−x Ba x Ti0.59 4+Ti0.41 3+O2.97. All fuel cells using LST or LSBT had high activity for conversion of hydrogen or methane, and the activity increased with the level of substitution by Ba. In addition, performance was enhanced when H2S was present in either CH4 or H2 fuel. There was good contact between YSZ electrolyte and each LSBT or LSB anode. [Copyright &y& Elsevier]

Abstract: Whereas Ce0.9Sr0.1Cr0.5V0.5O3 is an active fuel cell anode catalyst for conversion of only the H2S content of 0.5% H2S–CH4 at 850°C, inclusion of 5wt% NiO to form a composite catalyst enabled concurrent electrochemical conversion of CH4. A fuel cell with a 0.3mm thick YSZ membrane and Ce0.9Sr0.1Cr0.5V0.5O3 as anode catalyst had a maximum power density of 85mWcm−2 in 0.5% H2S–CH4 at 850°C, arising only from the electro-oxidation of H2S. Using a same thick membrane, promotion of the anode with 5wt% NiO increased the total anode electro-oxidation activity to afford maximum power density of 100mWcm−2 in 0.5% H2S–CH4. The same membrane provided 30mWcm−2 in pure CH4, showing that the incremental improvement arose substantially from CH4 conversion. Performance of each anode was stable for over 12h at maximum power output. XPS and XRD analyses showed that an increase in conductivity of Ce0.9Sr0.1Cr0.5V0.5O3 in H2S-containing environments resulted from a change in composition and structure from the tetragonal oxide to monoclinic Ce0.9Sr0.1Cr0.5V0.5(O,S)3. [Copyright &y& Elsevier]

Abstract: The stability and activity in 0.5% H2S–CH4 of Ce0.9Sr0.1VO3 and Ce0.9Sr0.1VO4 anode materials for H2S-containing CH4 fueled SOFCs have been determined. XRD showed that Ce0.9Sr0.1VO4 was reduced when the fuel gas was 0.5% H2S–CH4, while Ce0.9Sr0.1VO3 remained stable over 24h at 950°C. Electrochemical tests in 0.5% H2S–CH4 showed stable performance at 950 and 800°C for cells comprising Ce0.9Sr0.1VO3|YSZ|Pt. Comparison of fuel cell performances using 0.5% H2S–CH4, 0.5% H2S–N2 and 5% H2S–N2 as feeds showed that Ce0.9Sr0.1VO3 was not active for oxidation of methane, but highly active for conversion of H2S. Electrochemical impedance results were consistent with the finding that the anode was activated only in an environment that contained H2S. Conductivity measurements showed there was an increase in conductivity in H2S-containing environments, and that this increase resulted from a change in composition and structure from the oxide to monoclinic Ce0.9Sr0.1V(O,S)3, as evidenced by XPS and XRD analyses. [Copyright &y& Elsevier]

Abstract: The system LSBT/YSZ (LSBT is La0.4Sr0.5Ba0.1TiO3) is a promising combination as an anode material for full ceramic SOFCs. An anode comprising a porous layer of YSZ impregnated with LSBT shows good performance for conversion of high sulfur content fuels. The microstructures within the composite matrix were determined and correlated with the parameters of the production process. The anodes were characterized electrochemically using impedance spectroscopy (EIS) and potentiodynamic tests performed at 850 °C with various fuels to determine the effect of H2S in the feeds: H2, H2/H2S (5000 ppm), CH4, CH4/H2S (5000 ppm). The highest power densities (200 mW cm−2 in H2/H2S) were obtained for LSBT/YSZ composites after impregnation six times with LSBT, corresponding to 12.6 wt% LSBT; further impregnations dramatically decreased performance as a result of restricted access of fuel to active sites. [Copyright &y& Elsevier]

Abstract: Undoped BaTiO3 perovskite oxide is more effective than SrTiO3 and La2Ti2O7 oxide as anode catalyst in SOFC fueled with H2S-containing methane. Electrochemical performance, impedance spectroscopy and other characterizations show that pure BaTiO3 is a good anode catalyst for conversion of methane in SOFC, especially in H2S-containing atmospheres. Compared with SrTiO3 and La2Ti2O7 samples, the BaTiO3−based fuel cell has higher resistance to carbon deposition, better electrochemical performance and much higher stability during long term operation. A maximum power density of 135 mW cm−2 was achieved at 900 °C with 0.5% H2S–CH4 in a fuel cell having a 300 μm thick YSZ electrolyte. High catalytic activity for methane conversion, mixed electronic and ionic conductivity, and the surface basicity of BaTiO3 unexpectedly provides promising performance as anodes in SOFC. [Copyright &y& Elsevier]

A La 0.5 Sr 0.5 Fe 0.9 Mo 0.1 O 3-δ -CeO 2 (LSFM-CeO 2) composite was prepared by impregnating CeO 2 into porous La 0.5 Sr 0.5 Fe 0.9 Mo 0.1 O 3-δ perovskite and was used as an anode material for proton-conducting solid oxide fuel cells (SOFCs). The maximum power densities of the BaZr 0.1 Ce 0.7 Y 0.2 O 3-δ (BZCY) electrolyte-supported single cell with LSFM-CeO 2 as the anode reached 291 mW cm−2 and 190 mW cm−2 in hydrogen and ethane fuel at 750 °C, respectively, which are significantly higher than those of a single cell with only LSFM as the anode. Additionally, the ethylene selectivity and ethylene yield from ethane for the fuel cell at 750 °C were as high as 93.4% and 37.1%, respectively. The single cell also showed negligible degradation in performance and no carbon deposition during continuous operation for 22 h under an ethane fuel atmosphere. The improved electrochemical performance due to the impregnation of CeO 2 can be a result of enhanced electronic and ionic conductivity, abundant active sites, and a broad three-phase interface in the resultant composite anode. The LSFM-CeO 2 composite is believed to be a promising anode material for proton-conducting SOFCs for co-producing electricity and high-value chemicals from hydrocarbon fuels. [ABSTRACT FROM AUTHOR]

In situ exsolution of Co nanoparticles on perovskite framework has been successfully synthesized by firing the porous precursor SrMo 0.8 Co 0.1 Fe 0.1 O 3-δ (SMCFO) in reducing flow at 850 °C. A structure transformation (from mixed to pure cubic phase) and the growth of Co nanoparticles are observed in H 2 atmosphere. This leads to an increase in the oxygen vacancy content, which is beneficial to the electrical conduction and catalytic activity towards the oxidations of H 2 and C 2 H 6 . Moreover, this material exhibits good redox reversibility under the condition of multiple reduction and re-oxidation cycles, as confirmed by the thermogravimetric analysis (TGA) measurements. A protonic fuel cell (PFC) built with this newly developed material shows a comparable electrocatalytic activity in both C 2 H 6 and H 2 atmospheres while a considerably high power density of 377 mW cm −2 is achieved in H 2 and 268 mW cm −2 in C 2 H 6 at 750 °C. In addition, C 2 H 4 yield in the cell with Co-SMCFO as anode is considerably improved (11.9%–37.8% at 650–750 °C) with respect to the widely used chromium oxide. The good electrochemical performance, the improved C 2 H 6 partial dehydrogenation ability and the negligible carbon formation in the Co-SMCFO anode are the strong indications that the SMCFO is a promising catalyst for the cogeneration of C 2 H 4 and electricity, and can also be potentially utilized in the PFC directly fueled with hydrocarbon. [ABSTRACT FROM AUTHOR]

A layered Mo doped Pr 0.5 Ba 0.5 MnO 3−δ (Mo-PBMO) double perovskite oxide was prepared by a modified sol–gel method and the properties of the fabricated material are characterized by various technologies. The results of X-ray diffraction (XRD), H 2 -temperature programmed reduction (H 2 -TPR), NH 3 -temperature programmed desorption (NH 3 -TPD), and thermogravimetric analysis (TGA) demonstrate that the treatment in reducing atmosphere at high temperature lead to a significant phase transformation of the material to a single cubic phase as well as with the Mo in multiple oxidized states. Such character leads to the production of large amount of oxygen deficiency with facilitated oxygen diffusion. The electrochemical performance tests of half-cell and single cell SOFCs exhibit the promoted effect of Mo on catalytic activity for the oxidation of H 2 and CH 4 , indicating that Mo-PBMO could serve as an anode material candidate for SOFCs. [ABSTRACT FROM AUTHOR]