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Abstract: Y-doped BaCeO3−δ (BCY) powders synthesized using a combustion method are pure perovskite phases. The particles are uniform spherical particles about 50nm. The properties of BCY proton-conducting electrolyte sintered at different temperatures from pressed nanopowders were systematically investigated. Dense BCY pellets are obtained at temperatures higher than 1400°C for 10h. Electrical conductivity and resistance to CO2 atmosphere each increase with sintering temperature. Fuel cells having about 0.8mm thick BCY electrolyte and Pt electrodes co-produce 151mWcm−2 electrical power and value-added ethylene with selectivity over 90% at ethane conversion about 35% at 700°C. [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: 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]

Abstract: Electrochemical performance, impedance spectroscopy and carbon tolerance analysis show, for the first time, that molybdenum carbide has great potential for application as anode catalyst in proton-conducting solid oxide fuel cells. Ethylene and stable power density are coproduced from ethane in proton-conducting SOFC with molybdenum carbide as anode catalyst and BCZY as electrolyte. [Copyright &y& Elsevier]

Abstract Proton-conducting perovskite oxides such as doped barium cerate and barium zirconate are promising electrolytes for solid oxide fuel cells (SOFCs). Multiple-doped barium cerate perovskite oxide proton conductors of BaCe 0·7 Zr 0·1 Y 0.2-x Nd x O 3−δ (0 ≤ x ≤ 0.1) are prepared by solid state reaction and the properties of the fabricated material are characterized by various technologies. Nd doping improves the sinterability and Zr doping enhances the chemical stability in CO 2 atmosphere. The electrical conductivity order of the as-prepared electrolytes at elevated temperature in hydrogen atmosphere is: BaCe 0·7 Y 0·17 Zr 0.1 Nd 0.03 O 3−δ > BaCe 0·7 Y 0·2 Zr 0·1 O 3−δ > BaCe 0·7 Y 0·1 Zr 0.1 Nd 0.1 O 3−δ. Ethane is selectively dehydrogenated to ethylene with cogeneration of electrical power in the SOFC operated at 650–700 °C. The maximum power density of the SOFC is 123 mW cm−2 for ethane fuel and 138 mW cm−2 for hydrogen fuel at the 700 °C. These unique features make the multiple-doped barium cerate perovskite oxide a promising electrolyte for chemical-energy cogeneration in SOFCs. Highlights • BCZYN electrolyte with good sinterability and chemical stability toward CO 2. • 23% ethylene yield with 91% selectivity at 700 °C, co-generate 123 mW cm−2. • Environmentally friendly, without carbon dioxide emission. [ABSTRACT FROM AUTHOR]

Biogas, consisting of CH 4 , CO 2 and a small amount of H 2 S, is one of the most promising alternative energy sources. Solid oxide fuel cells (SOFCs) are ideal technologies to efficiently utilize biogas for producing electricity and heat. However, this is precluded because the conventional Ni-Y 2 O 3 stabilized ZrO 2 (Ni-YSZ) anode for SOFC is inclined to cause carbon formation as well as to form inert and non-conductive S-containing species in biogas. To directly utilize the biogas in SOFC, a hybrid anode material, combining the slightly compromised merits of the conventional Ni-YSZ cermet and the alternative anode, i.e., PrBaMn 2 O 5+δ perovskite oxide, is developed in this study. The PrBaMn 2 O 5+δ dramatically resists the carbon formation and S adsorption on Ni surface and at the same time, it serves as the CO 2 -captor, oxygen source and the medium for O 2− diffusion to accelerate both the carbon removal and S desorption processes. At 800 °C, the peak power density of the cell with the hybrid anode attains 1.35 W cm −2 in biogas, and no significant degradation is observed during the stability test. The hybrid anode, therefore, displays excellent activity, superior coke/sulfur resistance and stability in biogas, offering a promising technology for biogas utilization. [ABSTRACT FROM AUTHOR]

Abstract: The effects of H2S and H2O in the methane feed on carbon deposition in a La0.4Sr0.5Ba0.1TiO3 (LSBT) anode-based solid oxide fuel cell were investigated in this work under different operating conditions. Characterization was done using a combination of electrochemical, Fourier transform infra-red spectroscopy (FTIR), temperature-programmed oxidation (TPO) and X-ray photoelectron spectroscopy (XPS) measurements. As expected, carbon accumulation became more severe with increasing exposure time and operating temperature, but less severe in the presence of a current and/or steam. Addition of 0.5% H2S to the feed increased carbon accumulation and this carbon could not be removed effectively by co-feeding a small amount of steam to the anode. The resulting carbon was, however, easier to remove with oxygen as compared to that deposited by the H2S-containing dry feed. [Copyright &y& Elsevier]

CO 2 -poisoning effect on cathodes is an unnegligible problem for commercial application of solid oxide fuel cells (SOFCs). In order to enhance CO 2 tolerance of cathodes, partial replacement of Ba by Ca in BaCo 0·4 Fe 0·4 Zr 0·1 Y 0·1 O 3-δ (BCFZY) cathode is proposed in this study. The stability of Ba 0·95 Ca 0·05 Co 0·4 Fe 0·4 Zr 0·1 Y 0·1 O 3-δ (BCaCFZY) and BCFZY in CO 2 -containing atmosphere is investigated comparably. When tested in a symmetrical cell and exposed to air with 1% CO 2 or 10% CO 2 , the electrochemical performance of BCFZY cathode shows obviously degradation and carbonate particles are formed on the cathode surface. Exhilaratingly, the polarization resistance of BCaCFZY cathode is more stable and the cathode surface remains clean. The durability test in proton-conducting single cells further proves that the fine stability of BCaCFZY cathode can be achieved in air with 1% CO 2 atmosphere. In addition, thermodynamic analysis reveals the mechanism of Ca doping to improve stability. Ca dopant itself has a high CO 2 resistance and the introduction of Ca element reduces Ba segregation on surface. Base on the experimental results above, the BCaCFZY cathode is a promising candidate for SOFC applications. • Partially replacement of Ba by Ca increases BCFZY cathode resistance to CO 2. • CO 2 poisoning effect is evaluated in proton-conducting solid oxide fuel cells. • The effect of Ca/Ba substitution is analyzed by thermodynamic calculation. [ABSTRACT FROM AUTHOR]