Understanding and mitigating A-site surface enrichment in Ba-containing perovskites: a combined computational and experimental study of BaFeO<sub>3</sub>

Liu, Jiapeng; Kim, Jun Kyu; Wang, Yuhao; Kim, Hyunseung; Belotti, Alessio; Koo, Bonjae; Wang, Zheng; Jung, WooChul; Ciucci, Francesco

doi:10.1039/d2ee01813f

Cited by 11 publications

(5 citation statements)

References 72 publications

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“…In order to obtain additional information on the composition of the films, we have analyzed the stoichiometry by electron probe microanalysis (EPMA). Particularly, the stoichiometry of the PNMO films has revealed that samples grown under high oxygen pressures (PO 2 ≥ 350 mTorr) show a certain degree of Pr deficiency (not related to Pr migration as in, e.g., [ 30 ]). Cationic vacancies can have an impact on the properties of perovskite oxides [ 31 , 32 ].…”

Section: Introductionmentioning

confidence: 99%

X-ray Absorption Spectroscopy Study of Thickness Effects on the Structural and Magnetic Properties of Pr2−δNi1−xMn1+xO6−y Double Perovskite Thin Films

et al. 2022

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In this work, we report a systematic study of the influence of film thickness on the structural and magnetic properties of epitaxial thin films of Pr2−δNi1−xMn1+xO6−y (PNMO) double perovskite grown on top of two different (001)-SrTiO3 and (001)-LaAlO3 substrates by RF magnetron sputtering. A strong dependence of the structural and magnetic properties on the film thickness is found. The ferromagnetic transition temperature (TC) and saturation magnetization (Ms) are found to decrease when reducing the film thickness. In our case, the thinnest films show a loss of ferromagnetism at the film-substrate interface. In addition, the electronic structure of some characteristic PNMO samples is deeply analyzed using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) measurements and compared with theoretical simulations. Our results show that the oxidation states of Ni and Mn ions are stabilized as Ni2+ and Mn4+, thus the ferromagnetism is mainly due to Ni2+-O-Mn4+ superexchange interactions, even in samples with poor ferromagnetic properties. XMCD results also make evident large variations on the spin and orbital contributions to the magnetic moment as the film’s thickness decreases.

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Section: Introductionmentioning

confidence: 99%

X-ray Absorption Spectroscopy Study of Thickness Effects on the Structural and Magnetic Properties of Pr2−δNi1−xMn1+xO6−y Double Perovskite Thin Films

et al. 2022

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“…An ideal PCFC cathode should have high intrinsic activity for the reduction of oxygen to oxygen ions as well as high proton conductivity to increase the active reaction sites for water formation. [ 32,41,44,45 ] In our previous work, we have proved that the effect of hydration reaction on ORR in PCFCs can be negative due to the competitive adsorption between water and oxygen species over the cathode for active sites, and the decrease of oxygen partial pressure in the atmosphere by water dilution. [ 46–48 ] Therefore, we evaluated the electrocatalytic activities of single‐phase STF and a series of nanocomposite NSTF x electrodes ( x = 0.1, 0.2, 0.3, and 0.4) using proton‐conducting BZCYYb and oxygen‐ion conducting Sm 0.2 Ce 0.8 O 2 (SDC)‐supported symmetric cells.…”

Section: Resultsmentioning

confidence: 99%

New Strategy for Boosting Cathodic Performance of Protonic Ceramic Fuel Cells Through Incorporating a Superior Hydronation Second Phase

Zhou

Wang

et al. 2023

Energy & Environ Materials

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For protonic ceramic fuel cells, it is key to develop material with high intrinsic activity for oxygen activation and bulk proton conductivity enabling water formation at entire electrode surface. However, a higher water content which benefitting for the increasing proton conductivity will not only dilute the oxygen in the gas, but also suppress the O2 adsorption on the electrode surface. Herein, a new electrode design concept is proposed, that may overcome this dilemma. By introducing a second phase with high‐hydrating capability into a conventional cobalt‐free perovskite to form a unique nanocomposite electrode, high proton conductivity/concentration can be reached at low water content in atmosphere. In addition, the hydronation creates additional fast proton transport channel along the two‐phase interface. As a result, high protonic conductivity is reached, leading to a new breakthrough in performance for proton ceramic fuel cells and electrolysis cells devices among available air electrodes.

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“…For example, Feng et al observed a 6-fold increase in the reaction rate for the oxidation of propane using defective structures of LaCoO 3 [24]; similarly, Lindenthal et al obtained modified perovskites with Fe nanoparticles (NPs) that resulted in a CO formation-specific activity of 50 µmol•m −2 •s −1 , 3-fold higher than the undoped catalyst [25]. Additionally, A-site deficiency is useful to counterbalance their usually observed surface enrichment at the expense of B-site cations, the latter being redox active sites [26]. To further improve the catalytic activity of perovskites, surface decoration with active metals to form a metal-semiconductor heterostructure can be exploited [27,28].…”

Section: Introductionmentioning

confidence: 99%

Perovskite Oxide Catalysts for Enhanced CO2 Reduction: Embroidering Surface Decoration with Ni and Cu Nanoparticles

Osti,

Rizzato,

Cavazzani

et al. 2024

Catalysts

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The imperative reduction of carbon dioxide into valuable fuels stands as a crucial step in the transition towards a more sustainable energy system. Perovskite oxides, with their high compositional and property adjustability, emerge as promising catalysts for this purpose, whether employed independently or as a supporting matrix for other active metals. In this study, an A-site-deficient La0.9FeO3 perovskite underwent surface decoration with Ni, Cu or Ni + Cu via a citric acid-templated wet impregnation method. Following extensive characterization through XRD, N2 physisorption, H2-TPR, SEM-EDX, HAADF STEM-EDX mapping, CO2-TPD and XPS, the prepared powders underwent reduction under diluted H2 to yield metallic nanoparticles (NPs). The prepared catalysts were then evaluated for CO2 reduction in a CO2/H2 = 1/4 mixture. The deposition of Ni or Cu NPs on the perovskite support significantly enhanced the conversion of CO2, achieving a 50% conversion rate at 500 °C, albeit resulting in only CO as the final product. Notably, the catalyst featuring Ni-Cu co-deposition outperformed in the intermediate temperature range, exhibiting high selectivity for CH4 production around 350 °C. For this latter catalyst, a synergistic effect of the metal–support interaction was evidenced by H2-TPR and CO2-TPD experiments as well as a better nanoparticle dispersion. A remarkable stability in a 20 h time-span was also demonstrated for all catalysts, especially the one with Ni-Cu co-deposition.

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Understanding and mitigating A-site surface enrichment in Ba-containing perovskites: a combined computational and experimental study of BaFeO₃

Abstract: BaFeO3-based perovskites are promising cathode materials for intermediate-temperature solid oxide fuel cells and protonic ceramic fuel cells due to their high electrocatalytic activity. However, during operation Ba has been observed...

Cited by 11 publications

References 72 publications

X-ray Absorption Spectroscopy Study of Thickness Effects on the Structural and Magnetic Properties of Pr2−δNi1−xMn1+xO6−y Double Perovskite Thin Films

X-ray Absorption Spectroscopy Study of Thickness Effects on the Structural and Magnetic Properties of Pr2−δNi1−xMn1+xO6−y Double Perovskite Thin Films

New Strategy for Boosting Cathodic Performance of Protonic Ceramic Fuel Cells Through Incorporating a Superior Hydronation Second Phase

Perovskite Oxide Catalysts for Enhanced CO2 Reduction: Embroidering Surface Decoration with Ni and Cu Nanoparticles

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Understanding and mitigating A-site surface enrichment in Ba-containing perovskites: a combined computational and experimental study of BaFeO3

Abstract: BaFeO3-based perovskites are promising cathode materials for intermediate-temperature solid oxide fuel cells and protonic ceramic fuel cells due to their high electrocatalytic activity. However, during operation Ba has been observed...

Cited by 11 publications

References 72 publications

X-ray Absorption Spectroscopy Study of Thickness Effects on the Structural and Magnetic Properties of Pr2−δNi1−xMn1+xO6−y Double Perovskite Thin Films

X-ray Absorption Spectroscopy Study of Thickness Effects on the Structural and Magnetic Properties of Pr2−δNi1−xMn1+xO6−y Double Perovskite Thin Films

New Strategy for Boosting Cathodic Performance of Protonic Ceramic Fuel Cells Through Incorporating a Superior Hydronation Second Phase

Perovskite Oxide Catalysts for Enhanced CO2 Reduction: Embroidering Surface Decoration with Ni and Cu Nanoparticles

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Understanding and mitigating A-site surface enrichment in Ba-containing perovskites: a combined computational and experimental study of BaFeO₃