Interstitialcy diffusion of oxygen in tetragonal La2CoO4+δ

Kushima, Akihiro; Parfitt, David; Chroneos, Alexander; Yildiz, Bilge; Kilner, John A.; Grimes, Robin W.

doi:10.1039/c0cp01603a

Cited by 109 publications

(118 citation statements)

References 58 publications

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“…6,12,13,[17][18][19][20][21][22][23] In support of our second hypothesis, lattice strain was recently shown to alter the oxygen defect chemistry as well as the oxygen reaction and diffusion kinetics on perovskite oxides.…”

Section: Introductionsupporting

confidence: 58%

“…This is analogous to the interstitialcy path that governs the oxygen migration in the bulk of this material. 13 The energy barrier for this incorporation process on the undoped LSC 214 (100) is 0.77 eV ( Fig. 3(d)), which is lower than the one on LSC 113 (001) Fig.…”

Section: Reaction Kinetics At the Interfacementioning

confidence: 99%

“…In LSC 214 , therefore, oxygen most favorably diffuses along the [100] direction via the interstitialcy path. 13 The kinetics of oxygen diffusion in LSC 214 , however, does not significantly accelerate the overall ORR kinetics compared to LSC 113 because the migration barrier of oxygen in bulk LSC 113 (0.69 eV) 27 is similar to the one along the fast interstitialcy route in LSC 214 . Since the focus is on "surface incorporation rate of oxygen" on LSC 214 (100), oxygen diffusion in the bulk …”

Section: Reaction Kinetics At the Interfacementioning

confidence: 99%

“…To avoid the self-interaction errors that occur in the traditional DFT for strongly correlated electronic systems, we employed the DFT+U method within Dudarev's approach 41 accounting for the on-site Coulomb interaction in the localized d orbitals, with an effective U-J = 3.3 eV taken from the previous reports for LaCoO 3 27, 30 and La 2 CoO 4+δ . 13 For La, Co, and O, the standard PAW/PW91 potentials were used for our calculations, while for Sr, Sr_sv potential was applied. All calculations used a plane wave expansion with a cutoff of 400 eV and included spin polarization.…”

Section: Ground-state Structures and Energiesmentioning

confidence: 99%

“…2,3,[7][8][9][10] More recent studies highlight the potential of layered materials, such as Ruddlesden-Popper (RP) family of A n+1 B n O 3n+1 , as desirable cathodes due to their fast and anisotropic oxygen incorporation and transport properties. 6,[11][12][13][14] 15 Following up this study, Crumlin et al, using electrochemical impedance spectroscopy measurements, reported also an ORR activity enhancement up to about 10 3 -10 4 times at 550 °C on the thin film La 0.8 Sr 0.2 CoO 3-δ cathodes whose surfaces are decorated with (La 0.5 Sr 0.5 ) 2 CoO 4 islands (an thus, with a high density of LSC 113 /LSC 214 interfaces). 16 While it is evident that the interfacial regions are contributing to this unusually high ORR activity, the governing mechanism behind these empirical observations was not identified to date.…”

Section: Introductionmentioning

confidence: 99%

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Mechanism for enhanced oxygen reduction kinetics at the (La,Sr)CoO3−δ/(La,Sr)2CoO4+δ hetero-interface

Han

Yildiz

2012

Energy Environ. Sci.

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The recently reported fast oxygen reduction kinetics at the interface of (La,Sr)CoO 3-δ (LSC 113 ) and (La,Sr) 2 CoO 4+δ (LSC 214 ) phases opened up new questions for the potential role of dissimilar interfaces in advanced cathodes for solid oxide fuel cells (SOFCs). Using first-principles based calculations in the framework of density functional theory, we quantitatively probed the possible mechanisms that govern the oxygen reduction activity enhancement at this hetero-interface as a model system. Our findings show that both the strongly anisotropic oxygen incorporation kinetics on the LSC 214 and the lattice strain in the vicinity of the interface are important contributors to such enhancement. The LSC 214 (100) surface exposed to the ambient at the LSC 113 /LSC 214 interface facilitates oxygen incorporation because the oxygen molecules very favorably adsorb on it compared to the LSC 214 (001) and LSC 113 (001) surfaces, providing a large source term for oxygen incorporation. Lattice strain field present near the hetero-interface accelerates oxygen incorporation kinetics especially on LSC 113 (001). At 500 °C 4×10 2 times faster oxygen incorporation kinetics is predicted in the vicinity of the LSC 113 /LSC 214 heterointerface with 50% Sr-doped LSC 214 compared to that on the single phase LSC 113 (001) surface.Contributions from both the anisotropy and local strain effects are of comparable magnitude. The insights obtained in this work suggest that hetero-structures which have a large area of (100) surfaces and smaller thickness in [001] direction of the Ruddlesden-Popper phases, and larger tensile strain near the interface would be promising for high-performance cathodes.Keywords: solid oxide fuel cell, oxygen reduction reaction, cathode, anisotropy, strain, perovskite, Ruddlesden-Popper, (La,Sr)CoO 3 , (La,Sr) 2 CoO 4+δ , density functional theory * Corresponding author. Email: byildiz@mit.edu 2 Graphical AbstractAnisotropic oxygen incorporation on (La,Sr) 2 CoO 4+δ and the lattice strain near the (La,Sr)CoO 3-δ / (La,Sr) 2 CoO 4+δ interface serve as two possible sources to accelerate the oxygen reduction kinetics on the hetero-structure by 4×10 2 times at 500 °C. Broader contextHigh efficiency and fuel flexibility of Solid Oxide Fuel Cells (SOFCs) render them attractive as a sustainable energy conversion technology. There is growing interest in the design of dissimilar interfaces at the nano-scale to enable high-performance SOFC cathodes with fast oxygen reduction reaction (ORR) kinetics at lower temperatures than their traditional operation temperature of 800 °C. A motivating example for this purpose has been the hetero-structure made of the (La,Sr)CoO 3-δ and (La,Sr) 2 CoO 4+δ phases with highly active interfaces. Two previous experimental reports have observed 10 3 -10 4 times enhancement in ORR kinetics at 500-550 °C arising from the interface of these two phases. However, these empirical observationshave not yet reached a fundamental understanding of why these interfaces are so highly active...

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Section: Introductionsupporting

confidence: 58%

Section: Reaction Kinetics At the Interfacementioning

confidence: 99%

Section: Reaction Kinetics At the Interfacementioning

confidence: 99%

Section: Ground-state Structures and Energiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Mechanism for enhanced oxygen reduction kinetics at the (La,Sr)CoO3−δ/(La,Sr)2CoO4+δ hetero-interface

Han

Yildiz

2012

Energy Environ. Sci.

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119

118

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Charge Transfer in Oxide Solid Fuel Cells

Shi

Yun

2020

Solid Oxide Fuel Cells

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Electronic Activation of Cathode Superlattices at Elevated Temperatures – Source of Markedly Accelerated Oxygen Reduction Kinetics

Chen

Cai

Kuru

et al. 2013

Advanced Energy Materials

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102

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Solid‐oxide fuel cells are an attractive energy conversion technology for clean electric power production. To render them more affordable, discovery of new cathode materials with high reactivity to oxygen reduction reaction (ORR) at temperatures below 700 °C is needed. Recent studies have demonstrated that La0.8Sr0.2CoO3/(La0.5Sr0.5)2CoO4 (LSC113/214) hetero‐interfaces exhibit orders of magnitude faster ORR kinetics compared with either single phase at 500 °C. To obtain a microscopic level understanding and control of such unusual enhancement, we implemented a novel combination of in situ scanning tunneling spectroscopy and focused ion beam milling to probe the local electronic structure at nanometer resolution in model multilayer superlattices. At 200–300 °C, the LSC214 layers are electronically activated through an interfacial coupling with LSC113. Such electronic activation is expected to facilitate charge transfer to oxygen, and concurrent with the anisotropically fast oxygen incorporation on LSC214, quantitatively explains the vastly accelerated ORR kinetics near the LSC113/214 interface. Our results contribute to an improved understanding of oxide hetero‐interfaces at elevated temperatures and identify electronically coupled oxide structures as the basis of novel cathodes with exceptional performance.

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Interstitialcy diffusion of oxygen in tetragonal La₂CoO₄₊δ

Cited by 109 publications

References 58 publications

Mechanism for enhanced oxygen reduction kinetics at the (La,Sr)CoO3−δ/(La,Sr)2CoO4+δ hetero-interface

Mechanism for enhanced oxygen reduction kinetics at the (La,Sr)CoO3−δ/(La,Sr)2CoO4+δ hetero-interface

Charge Transfer in Oxide Solid Fuel Cells

Electronic Activation of Cathode Superlattices at Elevated Temperatures – Source of Markedly Accelerated Oxygen Reduction Kinetics

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