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The metal-ceramic composite Cu/Ce0.9Mn0.1O2-δ (Cu/CMO) is investigated as a fuel electrode for solid oxide cells (SOCs) regarding the interconversion between CO and CO2, and exhibits excellent anti-carbon and electrocatalytic performance. When the SOCs are operated in solid oxide fuel cell (SOFC) mode in CO2/CO = 50/50 atmosphere, the maximum power densities of the SOCs are 37, 88, and 151 mW/cm2 at 700, 750, and 800 °C, respectively, indicating that Cu/CMO electrode possesses excellent catalytic activity for CO oxidation. The Cu/CMO is also electrochemically active for CO2 reduction when the SOCs are operated in solid oxide electrolytic cell (SOEC) mode. At an applied voltage of 2.0 V, the current densities of the SOCs are 0.47, 0.87, and 1.36 A/cm2 at 700, 750, and 800 °C, respectively. Short-term durability measurement of CO2 electrolysis at various applied voltages shows that the SOCs is stable with only a small decrease in current density at 1.4 V, while the current density decreases more above 2.0 V, probably due to the deterioration of the electrode at high applied voltages. Long-term stability measurement of the SOCs at an applied voltage of 1.4 V for up to 200 h shows significant stability of the electrode. In this paper, the metal-ceramic composite Cu/CMO is used as a fuel electrode for SOCs and the performance in both SOEC and SOFC modes is investigated. The electrolysis of CO2 and oxidation of CO occurred at the fuel electrode Cu/CMO using CO2/CO = 50/50 mixture as the fuel gas to achieve the mutual conversion of CO2 and CO, respectively. After systematic electrochemical performance tests, SOCs using Cu/CMO as the fuel electrode can be reversibly converted in both SOEC and SOFC modes, achieving efficient conversion between chemical energy and renewable electricity. [ABSTRACT FROM AUTHOR]

Rare-earth site high entropy double perovskite oxides with different molar ratios have been evaluated as the cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFC). The effect of configuration entropy on crystal structure, electrical conductivity, electrochemical performance and stability are investigated. Our results reveal that the activity of all high entropy oxides show enhanced electrochemical activity. Among them, the equimolar one (HEO) exhibits the highest activity with a low polarization resistance of 0.05 Ω cm2 at 700 °C. Moreover, it exhibits excellent stability in the CO 2 -containing atmosphere. The enhanced activity and operational stability can be attributed to reduced surface Ba segregation and the formation of active and robust BaCoO 3-δ nanoparticles on HEO surface, rather than BaCO 3 and Co 3 O 4 phases. This work indicates that configurational entropy engineering is very effective for rational surface composition regulation. [ABSTRACT FROM AUTHOR]

In this paper, the catalytic activity of a ferrite/ceria composite ceramic fuel electrode La 0.9 Ca 0.1 Fe 0.9 Nb 0.1 O 3-δ /Sm 0.1 Ce 0.9 O 2−δ (LCFNb/SDC) for solid oxide reversible cells (SOCs) is studied by using YSZ (Zr 0.84 Y 0.16 O 2-δ ) and LSM/YSZ (LSM(La 0.8 Sr 0.2 MnO 3-δ )) as electrolyte and oxygen electrode, respectively. The asymmetrical LCFNb/SDC|YSZ|LSM/YSZ cells are prepared and evaluated electrochemically by using DC (cyclic voltammetry (CV) and galvanostatic) and AC impedance techniques in 50% CO: 50% CO 2 at the fuel electrode compartment. XRD results indicate LCFNb in the composite fuel electrode is stable in CO and CO 2 at high temperature and the LCFNb/SDC membane fuel electrode prepared by infiltration method presents high performance towards CO 2 reduction and CO oxidation. The polarization resistance under open circuit in a 50% CO: 50% CO 2 gas composition at 800 °C is 0.97 Ω cm 2 . However, both the CV and polarized impedance data show that the cell performance is higher for the electrolysis of CO 2 than for the oxidation of CO. The polarization resistance in 50% CO: 50% CO 2 at 1.4 V at 800 °C is 0.39 Ω cm 2 . Notably, the cell shows a highly stable activity towards CO 2 electrolysis at different applied voltages at the temperature of 800 °C. [ABSTRACT FROM AUTHOR]

A cermet fuel electrode Cu/Ce 0.6 Mn 0.3 Fe 0.1 O 2-δ (Cu/CMF) is proposed for a reversible solid oxide electrochemical cell (SOC) with CO/CO 2 as the shuttle. Cu is inert for the carbon deposition and CMF is electrochemically active for CO oxidation and CO 2 reduction. The electrode polarization resistances in CO at 700, 750 and 800 °C are 0.328, 0.207 and 0.155 Ω cm 2 , respectively, presenting high electrochemical activity towards CO oxidation. The maximal power densities can reach up to 303.3, 482.2 and 691.9 mW/cm 2 at 700, 750 and 800 °C, respectively. When the reversible SOCs are operated in solid oxide electrolysis cell mode, the polarization resistance of the electrolysis cell for pure CO 2 reduction at 800 °C has the minimal value of 0.126 Ω cm 2 at 1.8 V. At 2.0 V, the current densities can reach up to 0.584 1.219 and 2.204 A/cm 2 at 700, 750 and 800 °C, respectively. The durability of the cell in CO for as long as 200 h indicates the electrode has remarkable stability. And the short-term stability characteristics for CO 2 electrolysis at different voltages illustrate that the cell performs well below 2.0 V. The harsh reducing environment at 2.0 V may be detrimental to the Cu/CMF electrode. [ABSTRACT FROM AUTHOR]

Abstract: Ammonia offers several advantages over hydrogen as an alternative fuel. However, using ammonia as a hydrogen source for fuel cells has not been received enough attention. In present paper, Scandia-stabilized Zirconia (SSZ) thin film electrolyte and Ni-SSZ anode functional layer were developed by tape casting in order to obtain high power output performance in ammonia, the results of a SOFC running on ammonia were described and its performance was compared with that when running on hydrogen. In order to improve the performance of the cell at higher temperatures, the anode was modified by iron through infiltration. A direct comparison of the performance of the modified cell running on either hydrogen or ammonia showed that the cell in ammonia generated slightly higher power densities at 700 and 750 °C. The performance in ammonia, using the anode catalyst, was comparable to that in hydrogen indicating ammonia could be treated as a promising alternative fuel by selecting an appropriate catalyst. [Copyright &y& Elsevier]

Abstract: The anodic performances of Ni-Y2O3 stabilized ZrO2 (Ni-YSZ) modified by alkaline earth metal oxide BaO were investigated for solid oxide fuel cells operating in H2S-containing hydrogen fuels. The XRF and EDS results indicated that the amount of BaO was about 5%. The cell with BaO/Ni-YSZ anode exhibited almost constant peak power densities when the fuel was switched from wet hydrogen to 50ppm H2S contaminated wet hydrogen and good stability in wet H2S-contained hydrogen fuels with H2S concentration gradually increased from 5 to 50ppm. The EDS and XPS results demonstrated that no element S was detectable after sulfur poisoning testing. High water adsorption ability of BaO could be the primary reason for the high sulfur tolerance. The obtained results confirmed the previous conclusion that BaO/Ni interfaces can resist not only deactivation by coking but also sulfur poisoning of a conventional Ni-YSZ anode. [Copyright &y& Elsevier]

Abstract: BaZr0.1Ce0.7Y0.1Yb0.1O3−δ as a candidate electrolyte material is prepared by ethylene diamine tetraacetic acid assisted glycine-nitrate process. After calcining at 900°C, the single-phase perovskite is obtained due to the better distribution of starting materials and the more feasible reaction kinetic conditions than solid state reaction method. The relative densities reach 96.8 and 98.4% respectively after sintering the pressed pellets at 1280 and 1400°C for 10h. In humidified oxygen the ionic conductivities are 0.015, 0.045, 0.101 and 0.207Scm−1 at 500, 600, 700 and 800°C, respectively. In air and humidified oxygen the activation energies for ionic conductivity are 66.1 and 68.9kJmol−1. In humidified hydrogen, however, different activation energies occur in low and high temperature ranges. The thermal expansion curve inflections at 500–800°C with respect to possible phase changes are found. Zirconia aggregation possibly results in the higher activation energy and peculiar thermal expansion behavior. The results indicate the ethylene diamine tetraacetic acid assisted glycine-nitrate process is a very promising preparation method for solid oxide fuel cell practical application. [Copyright &y& Elsevier]

The stability of solid oxide fuel cells (SOFCs) cathodes is often severely damaged by impurity poisonings from Cr vapors. Here we report a medium entropy GdBa(Mn 0.2 Fe 0.2 Co 1.2 Ni 0.2 Cu 0.2)O 5+δ (ME-GBCO) double perovskite cathode, which exhibits remarkably improved Cr-tolerant ability. The polarization resistance (R p) of GBCO increases from ∼0.44 to ∼0.70 Ω cm2 after 20 h exposure to Cr in air at 700 °C. In contrast, R p value of ME-GBCO cathode increases from ∼0.16 to ∼0.24 Ω cm2 under the same condition. The enhanced operational stability is attributed to the in situ formed BaCoO 3-δ (BCO) nanoparticles on ME-GBCO surface, which is very inactive to Cr vapors. This work highlights that the configuration entropy modulation is an effective avenue for surface engineering and for the development of robust cathode materials for SOFCs. [ABSTRACT FROM AUTHOR]

[Display omitted] • A low-temperature high-performance ammonia-fueled SOFC was constructed. • A fuel cell was prepared by one step dry pressing without any sintering processes. • Peak power densities in ammonia were 501 and 755 mW cm−2 at 500 °C and 550 °C. • Ni-NCAL electrodes had high catalytic activity toward ammonia decomposition. • R p values of the cell in ammonia and hydrogen were 0.250 and 0.246 Ω cm−2 at 550 °C. In this work, a low-temperature symmetrical solid oxide fuel cell with Ni-NCAL|SDC/NCAL|Ni-NCAL (70 SDC:30 NCAL) configuration was successfully constructed by a simple dry press method. At 500 and 550 °C, the peak power densities of the cell in ammonia were 501 and 755 mW cm−2, and in hydrogen were 670 and 895 mW cm−2, respectively. EIS data showed that the R p values of the cell in ammonia and hydrogen at 550 °C were 0.250 and 0.246 Ω cm−2, respectively, indicating the excellent catalytic activity of the Ni-NCAL electrode toward ammonia decomposition and hydrogen oxidation. The different cell output can be ascribed to additional ammonia decomposition steps compared to hydrogen. The noticeable reaction product on the surface of the Ni foam was detrimental to ammonia decomposition. In summary, a symmetrical cell with SDC/NCAL semiconductor electrolyte and Ni-NCAL electrodes exhibited higher electrochemical performance at low temperature than the results reported to date. Therefore, higher electrochemical performance can be expected from this cell configuration with more efficient ammonia decomposition catalysts. [ABSTRACT FROM AUTHOR]

Abstract: Doubly doped CeO2 based anode with Y and Yb is first reported for direct methane solid oxide fuel cells. The power output of the cell with Ni–Ce0.8Y0.1Yb0.1O1.9 anode and stability at various temperatures are investigated when air is used as oxidant and pure H2, 5ppm H2S containing H2 and dry CH4 as fuel, respectively. At 750°C, the cell displays stable power output for 120h at 200mAcm−2 when fueled with dry CH4, suggesting the carbon deposit is largely absent on the anode, which is confirmed by the SEM observation and EDS results. The results also prove that the rare earth elements Y and Yb affect the sulfur tolerance performance of the anode in a cooperative fashion leading to good anode stability in the contaminated fuel. The SEM and EDS results provide evidence that the cell with Ni–Ce0.8Y0.1Yb0.1O1.9 anode is tolerant toward the H2S contamination. The remarkable performances suggest that co-doped CeO2 anode is an attractive electrode component for direct hydrocarbon solid oxide fuel cells and might also be used as a catalyst for reforming of hydrocarbon fuels and for removal of fuel gas contaminations such as sulfur. [Copyright &y& Elsevier]

Abstract: Significant improvements on sintering characteristic and electrical performance of traditional interconnect La0.7Ca0.3CrO3−δ were presented in this paper. For a composite interconnecting ceramic La0.7Ca0.3CrO3−δ /Ce0.8Nd0.2O1.9, it was found that the addition of Ce0.8Nd0.2O1.9 significantly increased the electrical conductivity of La0.7Ca0.3CrO3−δ both in air and in hydrogen. Among all the investigated specimens, La0.7Ca0.3CrO3−δ with 5wt% Ce0.8Nd0.2O1.9 possessed the maximal electrical conductivity. In air and hydrogen, the maximal electrical conductivity at 800°C were 55.4Scm−1 and 5.0Scm−1, respectively, which increased significantly as compared with La0.7Ca0.3CrO3−δ under the same conditions. With the increase of Ce0.8Nd0.2O1.9 content the relative density increased, reaching 97.1% from 93.9% of La0.7Ca0.3CrO3−δ . This indicated that Ce0.8Nd0.2O1.9 functioned as an effective sintering aid in enhancing the sinterability of the powders. The average coefficient of thermal expansion at 30–1000°C in air increased with Ce0.8Nd0.2O1.9 content. Most coefficients of thermal expansion of specimens are compatible with other cell components. The oxygen permeation measurement illustrated a negligible oxygen ionic conduction, indicating it is still an electronically conducting ceramic. Results indicate that this composite is suitable to be used as a high-performance interconnect for intermediate temperature solid oxide fuel cells. [Copyright &y& Elsevier]