Effect of oxygen vacancies on electrical conductivity of La0.5Sr0.5FeO3−δ from first-principles calculations

Shin, Yonghun; Doh, Kyung-Yeon; Kim, Seong Hun; Lee, June Ho; Bae, Hohan; Song, Sun-Ju; Lee, Donghwa

doi:10.1039/c9ta12734h

Cited by 47 publications

(17 citation statements)

References 55 publications

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“…A defect‐rich surface promotes easy desorption of intermediates at the active sites to accelerate the adsorption of fresh reactants, which is in agreement with the Sabatier principle of balanced adsorption and desorption of intermediates. An optimum defect concentration is, however, necessary because otherwise oxygen defects also reduce the charge‐carrier concentration and can thereby decrease the electronic conductivity; this phenomenon is quite prevalent in perovskite oxide lattices . Our characterization results clearly validate optimum defect concentrations in CoF‐2 and CoF‐3 and show a trend that can explain the relative electrochemical performances.…”

Section: Resultssupporting

confidence: 66%

“…An optimum defect concentration is, however,n ecessary because otherwise oxygen defects also reduce the charge-carrier concentrationa nd can thereby decrease the electronic conductivity;t his phenomenon is quite prevalent in perovskite oxide lattices. [29,65] Our characterization results clearly validate optimum defect concentrations in CoF-2 and CoF-3 and show at rend that can explain the relative electrochemical performances.…”

Section: Role Of Oxygen Defects In the Electrocatalytic Performancesupporting

confidence: 67%

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Oxygen‐Defect‐Rich Cobalt Ferrite Nanoparticles for Practical Water Electrolysis with High Activity and Durability

et al. 2020

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The scope of any metal oxide as a catalyst for driving electrocatalytic reactions depends on its electronic structure, which is correlated to its oxygen‐defect density. Likewise, to transform a spinel oxide, such as cobalt ferrite (CoFe2O4), into a worthy universal‐pH, bifunctional electrocatalyst for the hydrogen and oxygen evolution reactions (HER and OER, respectively), oxygen defects need to be regulated. Prepared by coprecipitation and inert calcination at 650 °C, CoFe2O4 nanoparticles (NPs) require 253 and 300 mV OER overpotentials to reach current densities of 10 and 100 mA cm−2, respectively, if nickel foam is used as a substrate. With cost‐effective carbon fiber paper, the OER overpotential increases to 372 mV at 10 mA cm−2 at pH 14. The NPs prepared at 550 °C require HER overpotentials of 218, 245, and 314 mV at −10 mA cm−2 in alkaline, acidic, and neutral pH, respectively. The intrinsic activity is reflected from turnover frequencies of >3 O2 s−1 and >5 H2 s−1 at overpotentials of 398 and 259 mV, respectively. If coupled for overall water splitting, the extremely durable two‐electrode electrolyzer requires a cell potential of only 1.63 V to reach 10 mA cm−2 at pH 14. The homologous couple also splits seawater at impressively low cell voltages of 1.72 and 1.47 V at room temperature and 80 °C, respectively.

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Section: Resultssupporting

confidence: 66%

Section: Role Of Oxygen Defects In the Electrocatalytic Performancesupporting

confidence: 67%

Oxygen‐Defect‐Rich Cobalt Ferrite Nanoparticles for Practical Water Electrolysis with High Activity and Durability

et al. 2020

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“…Ideally, OER intermediates (O*, OH*, and OOH*) should not bind too strongly to the active site of a perovskite, to facilitate for reasonable dynamics. Man et al utilized [108]. Density of states (DOS) calculations in Fig.…”

Section: Advantageous Intrinsic Effects Of Oxygen Vacancies In Perovsmentioning

confidence: 99%

“…Reproduced from Ref. [108] with permission from The Royal Chemical Society, Copyrights 2020 manifesting near 300 mV reduction in overpotential and 80 times higher specific activity at 1.7 V vs. RHE [116]. Chronoamperometric (CA) tests revealed that formation of oxygen vacancies in Sr 2 VFeAsO 3 − ẟ does not cause structural instabilities.…”

Section: Disadvantageous Effects Of Oxygen Vacancies In Perovskitesmentioning

confidence: 99%

“…This work gave rise to a simple and effective universal descriptor for OER reactions on oxide surfaces, including perovskites, and to an activity volcano plot. At the time, a few materials in La 0.5 Sr 0.5 FeO 3 − ẟ eventually lowers the conductivity and leads to metal-to-semiconductor transition at low partial pressures of O 2 [108]. Density of states (DOS) calculations in Fig.…”

Section: Advantageous Intrinsic Effects Of Oxygen Vacancies In Perovskitesmentioning

confidence: 99%

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Oxygen-deficient perovskites for oxygen evolution reaction in alkaline media: a review

2020

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Oxygen vacancies in complex metal oxides and specifically in perovskites are demonstrated to significantly enhance their electrocatalytic activities due to facilitating a degree of control in the material’s intrinsic properties. The reported enhancement in intrinsic OER activity of oxygen-deficient perovskites surfaces has inspired their fabrication via a myriad of schemes. Oxygen vacancies in perovskites are amongst the most favorable anionic or Schottky defects to be induced due to their low formation energies. This review discusses recent efforts for inducing oxygen vacancies in a multitude of perovskites, including facile and environmentally benign synthesis strategies, characterization techniques, and detailed insight into the intrinsic mechanistic modulation of perovskite electrocatalysts. Experimental, analytical, and computational techniques dedicated to the understanding of the improvement of OER activities upon oxygen vacancy induction are summarized in this work. The identification and utilization of intrinsic activity descriptors for the modulation of configurational structure, improvement in bulk charge transport, and favorable inflection of the electronic structure are also discussed. It is our foresight that the approaches, challenges, and prospects discussed herein will aid researchers in rationally designing highly active and stable perovskites that can outperform noble metal-based OER electrocatalysts.

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Exsolution Synthesis of Nanocomposite Perovskites with Tunable Electrical and Magnetic Properties

Wang

Syed

Ning

et al. 2021

Adv Funct Materials

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Nanostructured functional oxides play an important role in enabling clean energy technologies and novel memory and processor devices. Using thin‐film La0.6Sr0.4FeO3 (LSF) as a model system, the novel utility of exsolution in fabricating self‐assembled metal oxide nanocomposites with tunable functionalities is shown. Exsolution triggers the formation of metallic iron (Fe0) nanoparticles, Ruddlesden–Popper domains, and nm‐scale percolated Fe‐deficient channels in LSF. Combining multimodal characterization with numerical modeling, the chemical, magnetic, and electrical properties of the exsolution‐synthesized nanocomposite at different stages of Fe0 exsolution as well as during redox cycling are assessed. After exsolution, the electronic conductivity of the nanocomposite LSF increased by more than two orders of magnitude. Based on numerical analysis representing all the constituents, it is expected that this increase in conductivity originates mainly from the Fe‐deficient percolating channels formed during exsolution. Moreover, the exsolved nanocomposite is redox‐active even at moderate temperatures. Such redox capabilities can enable dynamic control of the nanocomposite functionality by tailoring the oxygen non‐stoichiometry. This concept is demonstrated with a continuous modulation of magnetization between 0 and 110 emu cm−3. These findings point out that exsolution may serve as a platform for scalable fabrication of complex metal oxide nanocomposites for electrochemical and electronic applications.

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Effect of oxygen vacancies on electrical conductivity of La_0.5Sr_0.5FeO_3−δ from first-principles calculations

Abstract: Metal to semiconductor transition by hole compensation of excess electrons from VO and localized VO state in La0.5Sr0.5FeO3−δ under low PO2.

Cited by 47 publications

References 55 publications

Oxygen‐Defect‐Rich Cobalt Ferrite Nanoparticles for Practical Water Electrolysis with High Activity and Durability

Oxygen‐Defect‐Rich Cobalt Ferrite Nanoparticles for Practical Water Electrolysis with High Activity and Durability

Oxygen-deficient perovskites for oxygen evolution reaction in alkaline media: a review

Exsolution Synthesis of Nanocomposite Perovskites with Tunable Electrical and Magnetic Properties

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