Underscoring the transport properties of yttrium-doped barium cerate in nominally dry oxidising conditions

Loureiro, Francisco J.A.; Ramasamy, Devaraj; Ribeiro, Alejandro F. G.; Mendes, Adélio; Fagg, Duncan P.

doi:10.1016/j.electacta.2020.135625

Cited by 14 publications

(33 citation statements)

References 35 publications

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“…Nonetheless, one of the requirements for operating in such low water vapour partial pressures is that the protonic conductivity must be maintained in order to ensure the functionality of the electrolyte membrane in these applications. In this respect, protonic conductors are complex materials as they are capable to offer mixed conductivity (protonic, oxide-ion and electronic), depending on the temperature and on the nature of the surrounding atmosphere [37,38]. One of the most promising compositions for this type of application is that of the yttrium-doped barium cerate, BaCe 1-x Y x O 3-δ (BCY), which has very high protonic conductivity at lower temperatures under humidified atmospheres (e.g.…”

Section: Thermodynamic Stability Of Carbon Dioxide Partial Pressure (mentioning

confidence: 99%

“…One of the most promising compositions for this type of application is that of the yttrium-doped barium cerate, BaCe 1-x Y x O 3-δ (BCY), which has very high protonic conductivity at lower temperatures under humidified atmospheres (e.g. $10 À3 Scm À1 at 400°C, p H2O $ 10 À2 atm) [1,38].…”

Section: Thermodynamic Stability Of Carbon Dioxide Partial Pressure (mentioning

confidence: 99%

“…In addition, at the higher temperature range, a notable decrease of the activation energy is observed in all cases, as a result of the exsolution of protons from the structure of BCY10, and the concomitant decrease of the protonic contribution to the electrical transport [37]. Interestingly, and also surprisingly at first Thermodynamic equilibrium for the formation of carbon dioxide from a hydrocarbon-based mixture and water at 400°C [38] (reproduced by permission of The Royal Society of Chemistry). sight, current results of total conductivity in nominally dry H 2 are close to those corresponding to the available data in literature for humidified H 2 ( Table 1).…”

Section: Thermodynamic Stability Of Carbon Dioxide Partial Pressure (mentioning

confidence: 99%

“…Later, Lim et al [56] determined the concentration of charge carriers in BCY10 by thermogravimetric analysis (TGA) under two different humidity conditions (dry and wet, p H2O $ 10 À5 and 10 À3 atm, respectively). More recently, Loureiro et al [38] focused on the determination of the transport properties of this composition at temperatures below 600°C and under very low humidity levels (p H2O ≤ 10 À4 atm).…”

Section: Electrochemical Properties Of Bcy10 In Low Humidity Oxidisinmentioning

confidence: 99%

“…In oxidising conditions, the absence of hydrogen species, shifts the water formation reaction, Eq. (19), away from the water product, leading to a lower intrinsic water vapour partial pressure that can, in turn, decrease the protonic transport number [38]. Therefore, at the intermediate temperature range, 350-600°C, it is necessary to externally add humidity to guarantee a sufficient level of protonic conductivity.…”

Section: Electrochemical Properties Of Bcy10 In Low Humidity Oxidisinmentioning

confidence: 99%

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Analysis of the Electrochemical Transport Properties of Doped Barium Cerate for Proton Conductivity in Low Humidity Conditions: A Review

Holz¹,

Graça²,

Loureiro³

et al. 2021

Analytical Chemistry - Advancement, Perspectives and Applications

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Proton-conducting perovskites are among the most promising electrolytes for Proton Ceramic Fuel Cells (PCFCs), electrolysers and separation membranes. Particularly, yttrium-doped barium cerate, BaCe1-xYxO3-δ (BCY), shows one of the highest protonic conductivities at intermediate temperatures (σ ∼ 10−3 S cm−1 at 400°C); values that are typically achieved under humidified atmospheres (p H2O ∼ 10−2 atm). However, BCY has commonly been discarded for such applications due to its instability in the presence of water vapour and carbonaceous atmospheres. A recent discovery has shown that BCY10 exhibits pure protonic conductivity under very low humidity contents (∼10−5–10−4 atm), owing to its very high equilibrium constant for hydration. This peculiar characteristic allows this material to retain its functionally as a proton conductor in such conditions, while preventing its decomposition. Hence, this chapter explores the electrochemical properties of the BaCe0.9Y0.1O3-δ (BCY10) composition, comprehensively establishing its limiting operation conditions through defect chemistry and thermodynamic analyses. Moreover, the importance of such conditions is highlighted with respect to potential industrially relevant hydrogenation/de-hydrogenation reactions at low temperatures under low humidity.

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Section: Thermodynamic Stability Of Carbon Dioxide Partial Pressure (mentioning

confidence: 99%

Section: Thermodynamic Stability Of Carbon Dioxide Partial Pressure (mentioning

confidence: 99%

Section: Thermodynamic Stability Of Carbon Dioxide Partial Pressure (mentioning

confidence: 99%

Section: Electrochemical Properties Of Bcy10 In Low Humidity Oxidisinmentioning

confidence: 99%

Section: Electrochemical Properties Of Bcy10 In Low Humidity Oxidisinmentioning

confidence: 99%

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Analysis of the Electrochemical Transport Properties of Doped Barium Cerate for Proton Conductivity in Low Humidity Conditions: A Review

Holz¹,

Graça²,

Loureiro³

et al. 2021

Analytical Chemistry - Advancement, Perspectives and Applications

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Tailoring the properties of dense yttrium‐doped barium zirconate ceramics with nickel oxide additives by manipulation of the sintering profile

Shakel

Loureiro

Antunes

et al. 2022

Intl J of Energy Research

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Summary Liquid phase sintering (LPS), by the addition of transition metal additives, has become one of the most preferred approaches to lower the sintering temperature of yttrium‐doped barium zirconate (BZY) proton‐conducting ceramics. Nonetheless, this approach is known to negatively impact the bulk conductivity of the parent perovskite phase, due to the significant incorporation of the sintering additive into the bulk composition. In the current work, we study the typical proton conducting material BaZr0.8Y0.2O3−δ (BZY20), prepared by One or Two‐step sintering strategies using 4 mol% NiO of sintering additive, compared against a control sample of pure BZY20. The main results demonstrate that the Two‐step approach is shown to minimise Ni interreaction with the BZY material, allowing this sample to maintain a higher hydration capacity than the One‐step material, as confirmed by X‐ray diffraction (XRD), scanning transmission electron microscopy/energy‐dispersive spectrocopy (STEM/EDS) and thermogravimetric (TG) measurements. Despite these benefits, the Two‐step approach presents a diminished bulk conductivity, which was ascribed to depletions in proton mobility due to “proton trapping” effects. In addition, the specific grain boundary conductivity was revealed to be higher in the Two‐step sample, as a possible result of a higher Ni accumulation in this region. Overall, this work opens an exciting new debate for further studies, in that prevention of Ni‐incorporation in the bulk material, as typically suggested in current literature, may not actually be the best method to improve the conductivity of samples densified by Ni‐additives and that control of potential defect associations may be the more critical method for conductivity tailoring.

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Assessment of the electrical properties and chemical stabilities of BaCe ₀ _. ₉ Y ₀ _. ₁ O ₃ _−δ and BaCe
Graça
¹
,
Loureiro
²
,
Holz
³

et al. 2022
Intl J of Energy Research
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Summary The electrochemical promotion of chemical reactions is gaining urgent interest, where proton conducting electrolyte membranes are used to promote industrially important hydrogenation or dehydrogenation reactions toward the desired chemical product. Nonetheless, most of these chemical reactions occur in the low‐to‐intermediate temperature range (300‐600°C), where the overall electrical properties of these membranes become strongly influenced by their grain boundary behavior and where the potential for their phase decomposition also becomes thermodynamically favored. To study these factors, we therefore, compare the stability and electrical properties of the popular electrolyte materials BaCe0.9Y0.1O3−δ (BCY10) and BaCe0.7Zr0.1Y0.2O3−δ (BCZY712) compositions by electrochemical impedance spectroscopy in a reducing H2 atmosphere in both wet (pH2O ~ 10−2 atm) and nominally dry conditions (pH2O ~ 10−4 atm), with special focus on their low‐temperature operation, an area of study that is currently lacking adequate information. The results highlight several critical points: (a) The small addition of zirconia is shown to negatively affect the hydration kinetics in the BCZY712 material, which needs at least 60 hours to reach equilibrium at 400°C, in contrast to the BCY10 sample. (b) Due to the increasing role of grain boundary behavior at lower temperatures, the BCY10 sample exhibits significant n‐type electronic conductivity in nominally dry conditions, whereas this effect is less noticeable for the BCZY712 sample. (c) Both samples show equivalent and high proton conductivity in nominally dry conditions at 400°C, a factor that can be highly beneficial to avoid potential side reactions in chemical synthesis. (d) Under higher levels of humidity BCY10 is shown to suffer conductivity degradation under prolonged operation at 400°C, corresponding to a change in its crystal structure from the orthorhombic to monoclinic phase. Conversely, BCZY712 does not show any signs of chemical degradation under the same conditions. Overall, the work provides vital information regarding the operation of these materials under low‐temperature conditions, providing valuable new insights for membrane selection in chemical synthesis applications.

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Underscoring the transport properties of yttrium-doped barium cerate in nominally dry oxidising conditions

Cited by 14 publications

References 35 publications

Analysis of the Electrochemical Transport Properties of Doped Barium Cerate for Proton Conductivity in Low Humidity Conditions: A Review

Analysis of the Electrochemical Transport Properties of Doped Barium Cerate for Proton Conductivity in Low Humidity Conditions: A Review

Tailoring the properties of dense yttrium‐doped barium zirconate ceramics with nickel oxide additives by manipulation of the sintering profile

Assessment of the electrical properties and chemical stabilities of BaCe ₀ _. ₉ Y ₀ _. ₁ O ₃ _−δ and BaCe
Graça
¹
,
Loureiro
²
,
Holz
³

et al. 2022
Intl J of Energy Research
Self Cite
4
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0
0
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Underscoring the transport properties of yttrium-doped barium cerate in nominally dry oxidising conditions

Cited by 14 publications

References 35 publications

Analysis of the Electrochemical Transport Properties of Doped Barium Cerate for Proton Conductivity in Low Humidity Conditions: A Review

Analysis of the Electrochemical Transport Properties of Doped Barium Cerate for Proton Conductivity in Low Humidity Conditions: A Review

Tailoring the properties of dense yttrium‐doped barium zirconate ceramics with nickel oxide additives by manipulation of the sintering profile

Assessment of the electrical properties and chemical stabilities of BaCe 0 . 9 Y 0 . 1 O 3 −δ and BaCe Graça1, Loureiro2, Holz3 et al. 2022Intl J of Energy ResearchSelf Cite4000View full textAdd to dashboardCite

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Assessment of the electrical properties and chemical stabilities of BaCe ₀ _. ₉ Y ₀ _. ₁ O ₃ _−δ and BaCe
Graça
¹
,
Loureiro
²
,
Holz
³

et al. 2022
Intl J of Energy Research
Self Cite
4
0
0
0
View full text Add to dashboard Cite