Role of oxygen anion diffusion in improved electrochemical performance of layered perovskite LnBa1−ySryCo2−xFexO5+δ (Ln=Pr, Nd, Gd) electrodes

Anjum, Uzma; Vashishtha, Saumye; Sinha, Nishant K.; Haider, M. Ali

doi:10.1016/j.ssi.2015.08.002

Cited by 19 publications

(21 citation statements)

References 48 publications

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“…34 The oxygen anion diffusion coefficient was calculated from the mean square displacement (MSD) versus time plot. 25 The root-mean-square deviation (rmsd) of the cations in the terminal surface was calculated to understand the crystallographic stability of the surfaces with respect to the bulk structure, which is given by the following formula…”

Section: ■ Methodologymentioning

confidence: 99%

“…For analysis, production run was carried out in the same ensemble for a total simulation time of 10 ns, which was visualized using Visual Molecular Dynamics Program (Version: 1.9.3, University of Illinois, Urbana-Champaign, USA) . The oxygen anion diffusion coefficient was calculated from the mean square displacement (MSD) versus time plot …”

Section: Methodsmentioning

confidence: 99%

“…Theoretical studies on double perovskite structured materials for SOFC electrodes are limited to separate studies on understanding oxygen anion diffusivities, , using molecular dynamics (MD) simulations or analyzing the energetics of oxygen vacancy formation energies using density functional theory (DFT) simulations. , Here, an attempt is made to combine both DFT and MD simulations to provide a comprehensive mechanistic insight into oxygen anion transport in the bulk of the material and in the near-surface zone linked with surface segregation.…”

Section: Introductionmentioning

confidence: 99%

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Identifying the Origin of the Limiting Process in a Double Perovskite PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ Thin-Film Electrode for Solid Oxide Fuel Cells

Anjum

Khan

Agarwal

et al. 2019

ACS Appl. Mater. Interfaces

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Oxygen reduction reaction in a double perovskite material, PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+δ (PBSCF), was studied for application as a cathode in a solid oxide fuel cell (SOFC). Electrochemical measurements were performed on a geometrically welldefined dense thin-film (0.8−2 μm thickness) electrode, fabricated as a symmetric cell. In combination with density functional theory (DFT) and molecular dynamics (MD) simulations, experiments provided an insight into the operating mechanism of the SOFC material tested at an open-circuit voltage. The dense thin-film electrode of PBSCF showed a thickness-dependent electrochemical performance, suggesting bulk diffusion limitation. To understand the origin of this diffusion-limiting electrochemical performance, DFT calculations were utilized to calculate the surface (γ) and oxygen vacancy formation (E OV ) energies. For example, E OV in the Pr plane (190 kJ/mol) of PBSCF was measured to be lower than that of the BaSr plane (E OV = 297 kJ/ mol). In addition, oxygen vacancies were difficult to be created in the BaSr/CoFe terminal surface (E OV = 341.6 kJ/mol) as compared to other terminal surfaces. MD simulations further elaborated on the nature of cation disordering in the surface and subsurface regions, consequently leading to the preferential segregation of the Ba cations to the surface, which is a known phenomenon in such double perovskite materials. Because of cation disordering and segregation of Ba species, the oxygen anion diffusivity (∼10 −12 cm 2 s −1 ), calculated from MD, in the near-surface region was observed to be 2 orders of magnitude lesser than that of the bulk (D = 2.98 × 10 −10 cm 2 s −1 ) of the material at 973 K. Surface characterization of the thin-film electrode using X-ray photoelectron spectroscopy was indicative of a nonperovskite Ba 2+ phase on the electrode surface. The segregation of Ba cations was linked with the transport of oxygen anions, which was limiting the electrochemical performance of the electrode.

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Section: ■ Methodologymentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Identifying the Origin of the Limiting Process in a Double Perovskite PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ Thin-Film Electrode for Solid Oxide Fuel Cells

Anjum

Khan

Agarwal

et al. 2019

ACS Appl. Mater. Interfaces

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“…MD simulations were performed using Forcite module of Material Studio 8.0 (Biovia, San Diego, USA) [11]. Born model was used between the ionic pairs to calculate the long-range columbic and short-range Buckingham potential approximation consisting of repulsive and dispersive terms.…”

Section: Experimental and Computational Methodsmentioning

confidence: 99%

“…Buckingham potential and structure parameters like, space group, fractional co-ordinates and lattice parameters were taken from other studies [11], [13]. The formal charges of ions; +3, +2, +3, +3 and 2, were set on each ion; Gd, Ba, Co, Fe and O respectively.…”

Section: Experimental and Computational Methodsmentioning

confidence: 99%

Nanoparticle Synthesis and Oxygen Anion Diffusion in Double Perovskite GdBaCo_2-xFe_xO_5+δ Electrodes for SOFC

et al. 2016

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Development of an intermediate temperature solid oxide fuel cell essentially require the synthesis of electrocatalytically active nanostructured cathode materials with fast oxygen anion transport and surface exchange properties. Double perovskite structured GaBaCo2O5+δ (GBCO) electrode showing an average particle size of less than 20 nm was synthesized by a bio-milling approach. In parallel, molecular dynamics (MD) simulations were utilised to calculate the effect of Fe doping at the B-site on the oxygen anion diffusivity of GdBaFexCo2-xO5.5 double perovskites. The oxygen diffusion was observed to be preferential in the a-b plane of GBCO with a value of D=2.8 x 10-7 cm2 s-1, calculated at 1173 K. The change in diffusion coefficient (D=1.95 x 10-7 cm2 s-1 at 1173 K) was negligible on doping 50% Fe in the structure. However, in 100% Fe substituted structure, GdBaFe2O5.5 (GBFO5.5), the diffusivity was significantly reduced (D=2 x 10-8 cm2 s-1 at 1173 K).

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Mechanistic Elucidation of Surface Cation Segregation in Double Perovskite PrBaCo2O5+δ Material using MD and DFT Simulations for Solid Oxide Fuel Cells

Anjum

Agarwal

Khan

et al. 2019

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Role of oxygen anion diffusion in improved electrochemical performance of layered perovskite LnBa1−ySryCo2−xFexO5+δ (Ln=Pr, Nd, Gd) electrodes

Cited by 19 publications

References 48 publications

Identifying the Origin of the Limiting Process in a Double Perovskite PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ Thin-Film Electrode for Solid Oxide Fuel Cells

Identifying the Origin of the Limiting Process in a Double Perovskite PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ Thin-Film Electrode for Solid Oxide Fuel Cells

Nanoparticle Synthesis and Oxygen Anion Diffusion in Double Perovskite GdBaCo_2-xFe_xO_5+δ Electrodes for SOFC

Mechanistic Elucidation of Surface Cation Segregation in Double Perovskite PrBaCo2O5+δ Material using MD and DFT Simulations for Solid Oxide Fuel Cells

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Role of oxygen anion diffusion in improved electrochemical performance of layered perovskite LnBa1−ySryCo2−xFexO5+δ (Ln=Pr, Nd, Gd) electrodes

Cited by 19 publications

References 48 publications

Identifying the Origin of the Limiting Process in a Double Perovskite PrBa0.5Sr0.5Co1.5Fe0.5O5+δ Thin-Film Electrode for Solid Oxide Fuel Cells

Identifying the Origin of the Limiting Process in a Double Perovskite PrBa0.5Sr0.5Co1.5Fe0.5O5+δ Thin-Film Electrode for Solid Oxide Fuel Cells

Nanoparticle Synthesis and Oxygen Anion Diffusion in Double Perovskite GdBaCo2-xFexO5+δ Electrodes for SOFC

Mechanistic Elucidation of Surface Cation Segregation in Double Perovskite PrBaCo2O5+δ Material using MD and DFT Simulations for Solid Oxide Fuel Cells

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Identifying the Origin of the Limiting Process in a Double Perovskite PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ Thin-Film Electrode for Solid Oxide Fuel Cells

Identifying the Origin of the Limiting Process in a Double Perovskite PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ Thin-Film Electrode for Solid Oxide Fuel Cells

Nanoparticle Synthesis and Oxygen Anion Diffusion in Double Perovskite GdBaCo_2-xFe_xO_5+δ Electrodes for SOFC