Development of composite steam electrodes for electrolyzers based on barium zirconate

Bausá, Nuria; Solís, Cecilia; Strandbakke, Ragnar; Serra, José M.

doi:10.1016/j.ssi.2017.03.020

Cited by 32 publications

(18 citation statements)

References 31 publications

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“…As an effect,

d_{z_{2}}

no longer forms an overlapping conduction band. In such a case instead of metallic conductivity, an activation type of conductivity is observed stemming from hopping of t 2g electron holes between cobalt . The electrical conductivity results are in accordance with previous …”

Section: Resultssupporting

confidence: 91%

Electric and magnetic properties of lanthanum barium cobaltite

et al. 2019

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The cubic Ba0.5La0.5CoO3‐δ was synthesized using solid state reaction. The structural properties were determined by the simultaneous refinement of Synchrotron Powder X‐ray Diffraction and Neutron Powder Diffraction data. Iodometric titration was used to examine the oxygen stoichiometry and average cobalt oxidation state. Low‐temperature magnetic studies show soft ferromagnetic character of fully oxidized material, with θP = 198(3) K and µeff = 2.11(2) µB. Electric measurements show the thermally activated nature of conductivity at low temperatures, whereas, due to the variable oxidation and spin state of cobalt, a single charge transport mechanism cannot be distinguished. Around room temperature, a wide transition from thermally activated conductivity to semi‐metallic behavior is observed. Under the inert atmosphere, the oxygen content lowers and the cation ordering takes place, leading to coexistence of two, ordered and disordered, phases. As a result of this change, thermally activated conductivity is observed also at high temperatures in inert atmosphere.

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“…As an effect,

d_{z_{2}}

Section: Resultssupporting

confidence: 91%

Electric and magnetic properties of lanthanum barium cobaltite

et al. 2019

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“…The two other RQ elements (i.e., R SP_1 , CPE SP_1 , R SP_2 , CPE SP_2 , green and violet semicircles respectively for La 0.5 Ba 0.5 CoO 3−δ ) correspond to the electrode response of the cells. The assignment of these electrochemical processes was carried out by evaluating the pseudocapacitance of the RQ elements (Table S1 for both La 0.5 Ba 0.5 CoO 3−δ and LaBaCo 2 O 5+δ ) obtained with the electrochemical model: i.e., La 0.5 Ba 0.5 CoO 3−δ ; ~10 −10 F/cm 2 for the first RQ element, assigned as the response of the electrolyte [8,9,10,35,36,37,38,39,40,41]; ~10 −4 F/cm 2 and 10 −2 F/cm 2 for the other two RQ elements, assigned as the response of the electrode [8,9,10,35,36,37,38,39,40,41]. …”

Section: Resultsmentioning

confidence: 99%

Effect of Cation Ordering on the Performance and Chemical Stability of Layered Double Perovskite Cathodes

et al. 2018

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The effect of A-site cation ordering on the cathode performance and chemical stability of A-site cation ordered LaBaCo2O5+δ and disordered La0.5Ba0.5CoO3−δ materials are reported. Symmetric half-cells with a proton-conducting BaZr0.9Y0.1O3−δ electrolyte were prepared by ceramic processing, and good chemical compatibility of the materials was demonstrated. Both A-site ordered LaBaCo2O5+δ and A-site disordered La0.5Ba0.5CoO3−δ yield excellent cathode performance with Area Specific Resistances as low as 7.4 and 11.5 Ω·cm2 at 400 °C and 0.16 and 0.32 Ω·cm2 at 600 °C in 3% humidified synthetic air respectively. The oxygen vacancy concentration, electrical conductivity, basicity of cations and crystal structure were evaluated to rationalize the electrochemical performance of the two materials. The combination of high-basicity elements and high electrical conductivity as well as sufficient oxygen vacancy concentration explains the excellent performance of both LaBaCo2O5+δ and La0.5Ba0.5CoO3−δ materials at high temperatures. At lower temperatures, oxygen-deficiency in both materials is greatly reduced, leading to decreased performance despite the high basicity and electrical conductivity. A-site cation ordering leads to a higher oxygen vacancy concentration, which explains the better performance of LaBaCo2O5+δ. Finally, the more pronounced oxygen deficiency of the cation ordered polymorph and the lower chemical stability at reducing conditions were confirmed by coulometric titration.

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“…19 A pure electronic conductor such as La 0.8 Sr 0.2 MnO 3Àd (LSM), is a promising electrode material for high-temperature due to its excellent stability, possesses insignicant oxide-ion conductivity and the risk of electrode delamination is minimized. [20][21][22][23] In this work, the advantages for composite electrodes based on a protonic conductor BaCe 0.2 Zr 0.7 Y 0.1 O 3Àd (BCZY27) [24][25][26] and an electronic conductor (LSM) are utilized. 20 The operation of LSM/BCZY27 composite anode is limited by surface-related processes, as inferred from the low frequencies of these processes characterized by electrochemical impedance spectroscopy (EIS) spectrum.…”

Section: Introductionmentioning

confidence: 99%

“…[20][21][22][23] In this work, the advantages for composite electrodes based on a protonic conductor BaCe 0.2 Zr 0.7 Y 0.1 O 3Àd (BCZY27) [24][25][26] and an electronic conductor (LSM) are utilized. 20 The operation of LSM/BCZY27 composite anode is limited by surface-related processes, as inferred from the low frequencies of these processes characterized by electrochemical impedance spectroscopy (EIS) spectrum. 27 Therefore, the use of a proper catalyst is decisive for an efficient anode development.…”

Section: Introductionmentioning

confidence: 99%

Robust catalytically-activated LSM-BCZY-based composite steam electrodes for proton ceramic electrolysis cells

Bausá

Serra

2019

RSC Adv.

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Backbone electrodes based on an electronic conductor and a protonic conductor show advantages for proton ceramic electrolyzer cells (PCECs). This work, aims to shed further light on the nature of the rate determining steps in the anode operation and improve the reaction rate in high steam pressure electrolysis mode by (i) adjusting their catalytic activity through electrode infiltration with catalytic electronic-conducting nanoparticles; and (ii) electrochemical activation of surface species by applying a net current through the electrode. A composite formed by La 0.8 Sr 0.2 MnO 3Àd (LSM) and BaCe 0.2 Zr 0.7 Y 0.1 O 3Àd (BCZY27) was deposited on proton-conducting BCZY27 electrolytes and studied in symmetrical cells to investigate the anode microstructure and electrochemical performance.Electrochemical impedance spectroscopy (EIS) measurements were performed in the 800-500 C range under 3 bar of pressure of wet air (75% of steam). LSM/BCZY27 50/50 vol% showed the best performance with an electrode polarization resistance (R p ) of 6.04 U cm 2 at 700 C and high steam pressure (0.75 bar of air and 2.25 bar of steam) whereas LSM/BCZY27 60/40 vol% presented a R p of 18.9 U cm 2 . The backbone electrodes were infiltrated using aqueous solutions of metal precursors to boost the electrocatalytic activity towards water splitting and oxygen evolution. The infiltrated cells were fired at 850 C for 2 h to obtain the desired crystalline nanoparticles (Pr 6 O 11 , CeO 2 , ZrO 2 and Pr 6 O 11 -CeO 2 ) and electrochemically tested under high steam pressures and bias currents to investigate the influence of catalytic activation on surface exchange kinetics. Among the tested catalysts, the lowest electrode polarization resistances (<0.2 U cm 2 ) were reached for the Pr 6 O 11 , CeO 2 and Pr 6 O 11 -CeO 2 catalysts at 700 C by applying current densities ranging from 1.57 to 14.15 mA cm À2 , and the Pr 6 O 11 -CeO 2activated LSM/BCZY27 electrode exhibited the best performance. Finally, the effect of pO 2 and pH 2 O was investigated aiming to characterize the rate limiting processes in the electrodes.

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Development of composite steam electrodes for electrolyzers based on barium zirconate

Cited by 32 publications

References 31 publications

Electric and magnetic properties of lanthanum barium cobaltite

Electric and magnetic properties of lanthanum barium cobaltite

Effect of Cation Ordering on the Performance and Chemical Stability of Layered Double Perovskite Cathodes

Robust catalytically-activated LSM-BCZY-based composite steam electrodes for proton ceramic electrolysis cells

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