Metallic Nanoparticles and Proton Conductivity: Improving Proton Conductivity of BaCe0.9Y0.1O3−δ Using a Catalytic Approach

Caldés, Maria Teresa; Kravchyk, Kostiantyn V.; Benamira, M.; Besnard, Nicolas; Gunes, Veyis; Bohnké, O.; Joubert, Olivier

doi:10.1021/cm301685x

Cited by 28 publications

(16 citation statements)

References 14 publications

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“…2E), group 3 dopants, produced microstroctures that were similar, or worse, than the BCZY63 control sample, despite having similar sintering conditions (1600 o C for 12 h). PdO is thought to create a small increase in point defect concentrations, a hypothesis which we along with others have previously proposed [14][15][16][17]. Thus we expect its grain size and density to be comparable or slightly better than the control.…”

Section: Microstructurementioning

confidence: 52%

Ionic transport modification in proton conducting BaCe0.6Zr0.3Y0.1O3−δ with transition metal oxide dopants

et al. 2016

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Proton conducting BaCe0.6Zr0.3Y0.1O3-δ (BCZY63) pellets were fabricated by the solid-state reactive sintering method whereby a small extra amount of a metal oxide additive (5 mol%) was included in the precursor mixture before sintering. The effect of the addition of six different metal oxide additives (CuO, ZnO, Fe2O3, MnO2, PdO, and Cr2O3) on the transport properties of BCZY63 was investigated. Although most additives (e.g. ZnO, Fe2O3, MnO2, Cr2O3) led to a decrease (sometimes minor) in conductivity, CuO and PdO dopants yielded an increase in total conductivity compared to the BCZY63 control. The enhancement in the total conductivity is found to be related to two factors: 1) the additive can act as a sintering aid to produce larger grain size; 2) substitutional doping of the BCZY structure by metal ions from additives can lead to increased bulk proton concentration. Due to its excellent sinterability and moderately improved proton conductivity, CuO-doped BCZY63 was subsequently applied as the dense electrolyte layer in protonic ceramic fuel cells utilizing a recently developed single firing step fabrication technique to produce high quality single cells that showed exceptional performance and long-term stability.

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Section: Microstructurementioning

confidence: 52%

Ionic transport modification in proton conducting BaCe0.6Zr0.3Y0.1O3−δ with transition metal oxide dopants

et al. 2016

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“…In the literature, the exsolution of metallic nanoparticles such as Ni dissolved as an oxide by cationic substitution into the compound and precipitated under reductive atmosphere after heating has been reported in nonstoichiometric perovskites, 28 and it was shown to increase the electrocatalytic properties. 29,30 In the same way, the presence of metallic molybdenum could enhance the electronic and catalytic properties of the materials. However, the decomposition into metallic molybdenum suggests that amorphous phase La 2 Mo 2 O 7−y is not thermodynamically stable under reductive atmosphere, as already mentioned by Vega-Castillo et al 10 Indeed, the reduction kinetics under diluted H 2 is very slow (Figures 2 and 4) but does not show any stabilization of the oxygen content of the amorphous phase: according to the model, the kinetic constant of Reaction C is very weak, and a correlatively very long reduction time would lead to full decomposition into metallic Mo.…”

Section: Inorganic Chemistrymentioning

confidence: 99%

Reduction Kinetics of La₂Mo₂O₉ and Phase Evolution during Reduction and Reoxidation

et al. 2016

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An amorphous reduced form of oxide ion conductor La2Mo2O9 had been proposed as sulfur-tolerant anode material for solid oxide fuel cell, but its oxygen content was not known. In this paper, we investigate the reduction kinetics by diluted hydrogen of La2Mo2O9 to amorphous, and the oxygen range of the amorphous form. The reduction kinetics is studied as a function of the powder specific surface area and of the temperature, on powders synthesized by solid state reaction and by polyol process using two different solvents. The reduction process was carried out by TGA under 10% H2 diluted in argon, and its kinetics is analyzed and modeled. As expected, small particles and high temperature lead to higher reduction rates. Several reduction steps were identified by XRD during the process. At 700 °C La2Mo2O9 is directly reduced into the amorphous phase La2Mo2O7-y, whereas at 760 °C reduction occurs through an intermediate crystallized La7Mo7O30 (≅ La2Mo2O8.57) phase before amorphization. In both cases, further reduction of La2Mo2O6.2 amorphous phase leads to an exsolution of metallic molybdenum and a molybdenum deficiency in the amorphous phase. Reoxidation of amorphous La2Mo2O7-y was studied by TGA, DTA and XRD. At low temperature in air, the reduced compounds are reoxidized while remaining amorphous. The annealing for 60 h at 350 °C in air of reduced La2Mo2O6.66, obtained beforehand by solid state reaction, gives an amorphous phase with composition La2Mo2O8.85. The existence domain of the reduced amorphous phase in terms of oxygen content therefore ranges at least from O6.2 to O8.85, thus including the composition La2Mo2O8.50 of the amorphous surface layer at the origin of a huge increase of ionic conductivity recently reported in nanowires of La2Mo2O9.

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“…This effect was ascribed to the formation of percolating space-charge layers with depleted charge carrier concentration around the metal particles. Caldes et al, on the other hand, reported an increase in the electrical conductivity of acceptor-doped BaCeO 3 containing Ni nanoparticles and attributed that to the enhanced catalytic splitting of H 2 resulting in enrichment of OH O • near the Ni particles. Moreover, Clark et al reported enhanced proton conductivity in Y- and Yb-co-doped BaZrO 3 containing Ni particles.…”

Section: Introductionmentioning

confidence: 99%

The Role of Space Charge at Metal/Oxide Interfaces in Proton Ceramic Electrochemical Cells

Saeed

Bjørheim

2020

J. Phys. Chem. C

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The contact potential and the resulting charge accumulation or depletion at the electrode/electrolyte interface are investigated for Ni and Cu group metals in contact with the stateof-the-art proton conductor acceptor-doped BaZrO 3 by firstprinciples calculations and thermodynamic modeling. The contact potential depends on the metal's work function and the defect chemical properties of the oxide, rendering it strongly temperature and atmosphere dependent. Above 900 K, most metals yield negative contact potentials and enrichment of protonic charge carriers at the electrode/electrolyte interface, facilitating charge transfer. Below 600 K, the contact potentials vary from positive to negative depending on the metal's work function. As such, higher work function metals lead to a space-charge contribution to the electrode impedance at lower temperatures. The prospects of exploiting charge accumulation (or depletion) characteristics of such interfaces are furthermore discussed with a focus on nanocomposite electrodes and solid-state electrochemical capacitors.

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Metallic Nanoparticles and Proton Conductivity: Improving Proton Conductivity of BaCe_0.9Y_0.1O_3−δ Using a Catalytic Approach

Cited by 28 publications

References 14 publications

Ionic transport modification in proton conducting BaCe0.6Zr0.3Y0.1O3−δ with transition metal oxide dopants

Ionic transport modification in proton conducting BaCe0.6Zr0.3Y0.1O3−δ with transition metal oxide dopants

Reduction Kinetics of La₂Mo₂O₉ and Phase Evolution during Reduction and Reoxidation

The Role of Space Charge at Metal/Oxide Interfaces in Proton Ceramic Electrochemical Cells

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Metallic Nanoparticles and Proton Conductivity: Improving Proton Conductivity of BaCe0.9Y0.1O3−δ Using a Catalytic Approach

Cited by 28 publications

References 14 publications

Ionic transport modification in proton conducting BaCe0.6Zr0.3Y0.1O3−δ with transition metal oxide dopants

Ionic transport modification in proton conducting BaCe0.6Zr0.3Y0.1O3−δ with transition metal oxide dopants

Reduction Kinetics of La2Mo2O9 and Phase Evolution during Reduction and Reoxidation

The Role of Space Charge at Metal/Oxide Interfaces in Proton Ceramic Electrochemical Cells

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Metallic Nanoparticles and Proton Conductivity: Improving Proton Conductivity of BaCe_0.9Y_0.1O_3−δ Using a Catalytic Approach

Reduction Kinetics of La₂Mo₂O₉ and Phase Evolution during Reduction and Reoxidation