Direct Synthesis of Methane from Co\u3csub\u3e2\u3c/sub\u3e-H\u3csub\u3e2\u3c/sub\u3eO Co-Electrolysis in Tubular Solid Oxide Electrolysis Cells

Directly converting CO2 to hydrocarbons offers a potential route for carbon-neutral energy technologies. Here we report a novel design, integrating the high-temperature CO2–H2O co-electrolysis and low-temperature Fischer–Tropsch synthesis in a single tubular unit, for the direct synthesis of methane from CO2 with a substantial yield of 11.84%

Reduced-Temperature Solid Oxide Fuel Cells Fabricated by Screen Printing

Electrolyte films of samaria-doped ceria (SDC, Sm0.2Ce0.8O1.9) are fabricated onto porous NiO-SDC substrates by a screen printing technique. A cathode layer, consisting of Sm0.5Sr0.5CoO3 and 10 wt % SDC, is subsequently screen printed on the electrolyte to form a single cell, which is tested at temperatures from 400 to 600°C. When humidified (3% H2O) hydrogen or methane is used as fuel and stationary air as oxidant, the maximum power densities are 188 (or 78) and 397 (or 304) mW/cm2 at 500 and 600°C, respectively. Impedance analysis indicates that the performances of the solid oxide fuel cells (SOFCs) below 550°C are determined primarily by the interfacial resistance, implying that the development of catalytically active electrode materials is critical to the successful development of high-performance SOFCs to be operated at temperatures below 600°C

Composite cathode based on yttria stabilized bismuth oxide for low-temperature solid oxide fuel cells

The investigation of composite cathodes consisting of silver and yttria stabilized bismuth oxide (YSB) for low-temperature honeycomb solid oxide fuel cells with stabilized zirconia as electrolyte was presented. The interfacial polarization resistances of a porous YSN-Ag cathode was about 0.3 ?? cm 2 at 600?? C. It was found by impedance analysis that the performance of an YSB-Ag composite cathode fired at 850?? C for 2 H was severely limited by gas transport due to insufficient porosity.open464

La\u3csub\u3e0.85\u3c/sub\u3eSr\u3csub\u3e0.15\u3c/sub\u3eMnO\u3csub\u3e3−\u3c/sub\u3e Infiltrated Y\u3csub\u3e0.5\u3c/sub\u3eBi\u3csub\u3e1.5\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e Cathodes for Intermediate-Temperature Solid Oxide Fuel Cells

Porous yttria-stabilized bismuth oxides (YSB) were investigated as the backbones for La0.85Sr0.15MnO3−(LSM) infiltrated cathodes in intermediate-temperature solid oxide fuel cells. The cathodes were evaluated using anode-supported single cells with scandia-stabilized zirconia as the electrolytes. With humidified H2 as the fuel, the cell showed peak power density of 0.33, 0.52, and 0.74 W cm−2 at 650, 700, and 750°C, respectively. At 650°C, the cell polarization resistance was only 1.38 Ω cm2, \u3c50% of the lowest value previously reported, indicating that YSB is a promising backbone for the LSM infiltrated cathode

Sr\u3csub\u3e2\u3c/sub\u3eFe\u3csub\u3e1.5\u3c/sub\u3eMo\u3csub\u3e0.5\u3c/sub\u3eO\u3csub\u3e6-δ\u3c/sub\u3e – Sm\u3csub\u3e0.2\u3c/sub\u3eCe\u3csub\u3e0.8\u3c/sub\u3eO\u3csub\u3e1.9\u3c/sub\u3e Composite Anodes for Intermediate-Temperature Solid Oxide Fuel Cells

Sr2Fe1.5Mo0.5O6−δ (SFM) perovskite is carefully investigated as an anode material for solid oxide fuel cells with LaGaO3-based electrolytes. Its electronic conductivity under anodic atmosphere is measured with four-probe method while its ionic conductivity is determined with oxygen permeation measurement. Samaria doped ceria (SDC) is incorporated into SFM electrode to improve the anodic performance. A strong relation is observed between SDC addition and polarization losses, suggesting that the internal SFM-SDC contacts are active for H2 oxidation. The best electrode performance is achieved for the composite with 30 wt% SDC addition, resulting in an interfacial polarization resistance of 0.258 Ω cm2 at 700◦C for La0.8Sr0.2Ga0.8Mg0.2O3−δ supported single cells. Electrochemical impedance spectroscopy analysis indicates that the high performance of SFM-SDC composite anodes is likely due to the high ionic conductivity and electro-catalytic activity of SDC by promoting the ionic exchange processes. Redox cycle treatment shows that SDC addition can even improve the redox tolerance of SFM anodes

Sr\u3csub\u3e2\u3c/sub\u3eFe\u3csub\u3e1.5\u3c/sub\u3eMo\u3csub\u3e0.5\u3c/sub\u3eO\u3csub\u3e6\u3c/sub\u3e as Cathodes for Intermediate-Temperature Solid Oxide Fuel Cells with La\u3csub\u3e0.8\u3c/sub\u3eSr\u3csub\u3e0.2\u3c/sub\u3eGa\u3csub\u3e0.87\u3c/sub\u3eMg\u3csub\u3e0.13\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e Electrolyte

The performance of Sr2Fe1.5Mo0.5O6 (SFMO) as a cathode material has been investigated in this study. The oxygen ionic conductivityof SFMO reaches 0.13 S cm-1 at 800°C in air. The chemical diffusion coefficient (Dchem) and surface exchange constant (kex) of SFMO at 750°C are 5.0 x 10-6 cm2 s-1 and 2.8 x 10-5 cm s-1, respectively, suggesting that SFMO may have good electrochemicalactivity for oxygen reduction. SFMO shows a thermal expansion coefficient (TEC) of 14.5 x 10-6 K-1 the temperature range of200–760°C in air. The polarization resistance of the SFMO cathode is 0.076 Ω cm2 at 800°C in air under open-circuit conditions measured on symmetrical cells with La0.8Sr0.2Ga0.87Mg0.13O3 (LSGM) electrolytes. Dependence of SFMO cathode polarizationresistance on the oxygen partial pressure and the cathode overpotentials at different temperatures are also studied. SFMO shows an exchange current density of 0.186 A cm-2 at 800°C in air. Single cells with the configuration of Ni-La0.4Ce0.6O2(LCO)|LCO|LSGM|SFMO show peak power densities of 349, 468, and 613 mW cm-2 at 750, 800, and 850°C, respectively using H2 as the fuel and ambient air as the oxidant. These results indicate that SFMO is a promising cathode candidate for intermediate-temperature solid oxide fuel cells with LSGM electrolyte

Influence of ionic conductivity of the nano-particulate coating phase on oxygen surface exchange of La0.58Sr0.4Co0.2Fe0.8O3-δ

The oxygen surface exchange kinetics of mixed-conducting perovskite La0.58Sr0.4Co0.2Fe0.8O3 d (LSCF) ceramics coated with a porous nano-particulate layer of either gadolinea (Gd2O3), ceria (CeO2) or 20 mol% Gd-doped ceria (GCO) was determined by electrical conductivity relaxation (ECR). The measurements were performed in the temperature range 700–900 C, following pO2-step changes between 0.2 and 0.4 atm. The apparent value of the surface exchange coefficient, kchem, is found to vary with the loading amount and ionic conductivity of the coated phase whilst, as expected, the chemical diffusion coefficient Dchem remains invariant with the applied coating. Partial coverage of the LSCF surface with non-ionic conductive Gd2O3 or CeO2 lowers the value of kchem relative to that observed for bare LSCF, which is attributed to surface blocking effects. In contrast, partial coverage of LSCF with GCO electrolyte particles enhances the apparent value of kchem up to a factor of 6 compared to bare LSCF. The data of pulse isotope exchange (PIE) measurements show that the surface exchange reaction on bare LSCF is predominantly limited by dissociative adsorption of O2. Different mechanisms for the improved oxygen surface exchange kinetics after partially covering the LSCF surface with GCO are discussed