Influence of CO2 on the oxygen permeation performance and the microstructure of perovskite-type (Ba0.5Sr0.5)(Co0.8Fe0.2)O3−δ membranes

Arnold, Mirko; Wang, Haihui; Feldhoff, Armin

doi:10.1016/j.memsci.2007.01.032

Cited by 359 publications

(199 citation statements)

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“…Even though relatively long annealing times were employed (25 min at 590 °C ( Figure 2) and 2 h at 500 °C (not shown)), the measured 18 O fraction in the bulk was found to be close to the natural isotope abundance. Recently it has been shown that carbonates with the general formula (Ba,Sr)CO3 form on the surface of BSCF5582 when exposed to a CO2-containing atmosphere, and drastically decrease the oxygen permeation flux through BSCF membranes [17] as well as the chemical surface exchange coefficient of oxygen of dense BSCF samples [18]. The decomposition of the surface carbonate in BSCF5582 was observed at temperatures higher than 800 °C [18].…”

Section: Resultsmentioning

confidence: 99%

Oxygen tracer diffusion and surface exchange kinetics in Ba0.5Sr0.5Co0.8Fe0.2O3−δ

et al. 2014

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Section: Resultsmentioning

confidence: 99%

Oxygen tracer diffusion and surface exchange kinetics in Ba0.5Sr0.5Co0.8Fe0.2O3−δ

et al. 2014

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“…However, the listed materials are limited by poor chemical stability under the large oxygen concentration gradient encountered during membrane operation, with one side of the membrane exposed to pressurized air and the other side to a reducing or CO 2 -containing atmosphere. [10][11][12] Even at a concentration of 300 ppm, the presence of CO 2 is a major issue for, e.g., BSCF due to the carbonation reaction associated with the presence of earth alkali metals in the perovskite structure. 13 Alternatively, lanthanide-substituted ceria materials combine rather high oxygen-ion conductivities, redox catalytic properties and chemical compatibility with water and CO 2 at high temperatures.…”

Section: 2mentioning

confidence: 99%

Bulk transport and oxygen surface exchange of the mixed ionic–electronic conductor Ce1−xTbxO2−δ (x = 0.1, 0.2, 0.5)

et al. 2013

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Bulk ionic and electronic transport properties and the rate of oxygen surface exchange of Tb-doped ceria have been evaluated as a function of Tb concentration, aiming to assess the potential use of the materials as high-temperature oxygen-transport membranes and oxygen reduction catalysts. The materials were synthesized by the co-precipitation method. Cobalt oxide (2 mol%) was added in order to improve sinterability and conductivity. The materials were studied by means of X-ray diffraction (XRD), temperatureprogrammed desorption (TPD), thermogravimetry (TG), DC-conductivity and UV-vis spectrophotometry. The results indicate that the extent of mixed ionic-electronic conductivity is a function of temperature and can be tuned by modifying the Tb-(and Co-doping) concentration. Low Tb-content materials (x ¼ 0.1 and 0.2) are predominant ionic conductors, but the materials with 50 mol% Tb show both p-type electronic and ionic conductivity. The enhanced electronic conduction in Ce 0.5 Tb 0.5 O 2Àd is associated with narrowing of the band gap upon doping ceria with Tb. In addition, the surface chemistry of the samples was investigated by means of X-ray photoelectron spectroscopy (XPS) and pulse isotopic exchange (PIE). The surface exchange rate is found to increase on increasing the level of Tb doping. The highest surface exchange rates in this study are found for materials doped with 50 mol% Tb.

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“…6,[25][26][27][28] In addition, BSCF is susceptible to CO 2 contamination, forming Sr and Ba carbonates. Such carbonates are prone to be formed already with atmosphere containing 1% CO 2 , at temperatures below 1173 K, [29][30][31][32] causing a degradation in BSCF oxygen activity.…”

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Infiltration, Overpotential and Ageing Effects on Cathodes for Solid Oxide Fuel Cells: La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δversus Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ

Giuliano

Carpanese

Clematis

et al. 2017

J. Electrochem. Soc.

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The two half-cell systems were compared to evaluate the influence of infiltration, overpotential and ageing on their performance and stability. Structure, microstructure and chemical composition were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with Energy Dispersive X-ray spectroscopy (EDX), whereas redox behavior was evaluated through temperature programmed reduction (TPR) and thermal gravimetric analysis (TGA) in combination with electrochemical impedance spectroscopy (EIS), which was also used to test the electrochemical performance. A decrease of polarization resistance for both infiltrated electrodes, compared to the reference ones, was highlighted at open circuit voltage (OCV), although the BSCF-based cathode was more benefitted more from infiltration than the LSCF-based one. Moreover, the application of cathodic overpotentials (−0.1 to −0.3 V) resulted in opposite effects on the LSCF-and BSCF-based cathodes, highlighting a different response of the oxygen vacancies to the applied voltage for the two perovskite compositions. The positive effect of the LSM layer was further confirmed by the observed improvement in long-term stability of both infiltrated perovskite-type systems. 1 They exhibit mixed ionic and electronic conductivity, with excellent charge and mass transfer properties 2 and high oxygen exchange surface coefficients. 3 Their excellent activity for oxygen reduction has been proved widely. [4][5][6][7][8][9][10] Although the structure and electrochemical processes of LSCF and BSCF are quite different, both of them have long-term stability and redox behavior issues to be clarified, in order to be used as cathode materials in commercial devices. Indeed, when used as cathodes in intermediate-temperatures solid oxide fuel cells (IT-SOFCs), they suffer from chemical and structural instability, which causes degradation during operation time. Moreover, the correlation between their redox behavior under electrochemical operating conditions is still unclear. Many studies have been devoted to investigating LSCF degradation and several causes have been reported, among them: i) mutual cations diffusion between interfaces with consequent atoms depletion and phase separation, [11][12][13][14][15][16] ii) LSCF grain coarsening, 17 iii) reactivity with YSZ-based electrolytes, even with ceria-based barrier layer, 18 iv) impurity contamination, namely Cr from metal interconnects and B from sealing when the cell is inside a stack.19-21 Some recent work performed on an LSCF/CGO (Ce 0.9 Gd 0.1 O 2-δ ) composite cathode on a YSZ electrolyte with a CGO barrier layer 11 affirms that Sr depletion, phase separation and cations inter-diffusion occur mainly during the fabrication process, with negligible contributions during long-term * Electrochemical Society Member.e Present Address: R&D Manufacturing Support Dept., Ansaldo Energia, Via Nicola Lorenzi 8, I-16152 Genoa. z E-mail: carpanese@unige.it operation (973 K). On the other hand, some previous works conversely found that LS...

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Influence of CO2 on the oxygen permeation performance and the microstructure of perovskite-type (Ba0.5Sr0.5)(Co0.8Fe0.2)O3−δ membranes

Cited by 359 publications

References 27 publications

Oxygen tracer diffusion and surface exchange kinetics in Ba0.5Sr0.5Co0.8Fe0.2O3−δ

Oxygen tracer diffusion and surface exchange kinetics in Ba0.5Sr0.5Co0.8Fe0.2O3−δ

Bulk transport and oxygen surface exchange of the mixed ionic–electronic conductor Ce1−xTbxO2−δ (x = 0.1, 0.2, 0.5)

Infiltration, Overpotential and Ageing Effects on Cathodes for Solid Oxide Fuel Cells: La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δversus Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ

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Influence of CO2 on the oxygen permeation performance and the microstructure of perovskite-type (Ba0.5Sr0.5)(Co0.8Fe0.2)O3−δ membranes

Cited by 359 publications

References 27 publications

Oxygen tracer diffusion and surface exchange kinetics in Ba0.5Sr0.5Co0.8Fe0.2O3−δ

Oxygen tracer diffusion and surface exchange kinetics in Ba0.5Sr0.5Co0.8Fe0.2O3−δ

Bulk transport and oxygen surface exchange of the mixed ionic–electronic conductor Ce1−xTbxO2−δ (x = 0.1, 0.2, 0.5)

Infiltration, Overpotential and Ageing Effects on Cathodes for Solid Oxide Fuel Cells: La0.6Sr0.4Co0.2Fe0.8O3-δversus Ba0.5Sr0.5Co0.8Fe0.2O3-δ

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Infiltration, Overpotential and Ageing Effects on Cathodes for Solid Oxide Fuel Cells: La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δversus Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ