Thickness dependent OER electrocatalysis of epitaxial LaFeO<sub>3</sub> thin films

Burton, Andricus; Paudel, Rajendra; Matthews, Bethany E.; Sassi, Michel; Spurgeon, Steven R.; Farnum, Byron H.; Comès, R.

doi:10.1039/d1ta07142d

Cited by 19 publications

(11 citation statements)

References 36 publications

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“…Through atomic-level control of synthesis in form of epitaxial thin films and heterostructures it is now possible to create desired combinations of different chemical compositions for perovskite oxides ( Gunkel et al, 2017 ; Baniecki et al, 2019 ). This allows engineering surface cover layers ( Akbashev et al, 2018 ; Heymann et al, 2022 ), and controlling chemical gradients and electronic properties independently via charge-transfer processes ( Gunkel et al, 2020b ; Burton et al, 2022 ) or sub-surface engineering ( Akbashev et al, 2018 ; Zhang et al, 2020 ), and enables a systematic understanding and tuning of activity and degradation from atomically defined model systems ( Weber and Gunkel, 2019 ). This enhanced material control with atomically smooth catalyst surfaces comes at the cost of a minimized contact area between catalyst and electrolyte, limiting the technological relevance of epitaxial systems.…”

Section: Atomistic Understanding Of Activity and Degradation Relies O...mentioning

confidence: 99%

Activity-Stability Relationships in Oxide Electrocatalysts for Water Electrolysis

et al. 2022

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The oxygen evolution reaction (OER) is one of the key kinetically limiting half reactions in electrochemical energy conversion. Model epitaxial catalysts have emerged as a platform to identify structure-function-relationships at the atomic level, a prerequisite to establish advanced catalyst design rules. Previous work identified an inverse relationship between activity and the stability of noble metal and oxide OER catalysts in both acidic and alkaline environments: The most active catalysts for the anodic OER are chemically unstable under reaction conditions leading to fast catalyst dissolution or amorphization, while the most stable catalysts lack sufficient activity. In this perspective, we discuss the role that epitaxial catalysts play in identifying this activity-stability-dilemma and introduce examples of how they can help overcome it. After a brief review of previously observed activity-stability-relationships, we will investigate the dependence of both activity and stability as a function of crystal facet. Our experiments reveal that the inverse relationship is not universal and does not hold for all perovskite oxides in the same manner. In fact, we find that facet-controlled epitaxial La0.6Sr0.4CoO3-δ catalysts follow the inverse relationship, while for LaNiO3-δ, the (111) facet is both the most active and the most stable. In addition, we show that both activity and stability can be enhanced simultaneously by moving from La-rich to Ni-rich termination layers. These examples show that the previously observed inverse activity-stability-relationship can be overcome for select materials and through careful control of the atomic arrangement at the solid-liquid interface. This realization re-opens the search for active and stable catalysts for water electrolysis that are made from earth-abundant elements. At the same time, these results showcase that additional stabilization via material design strategies will be required to induce a general departure from inverse stability-activity relationships among the transition metal oxide catalysts to ultimately grant access to the full range of available oxides for OER catalysis.

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Section: Atomistic Understanding Of Activity and Degradation Relies O...mentioning

confidence: 99%

Activity-Stability Relationships in Oxide Electrocatalysts for Water Electrolysis

et al. 2022

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“…Therefore, the chemical state of the surface of SL was examined through Fe 2p XPS spectra. The Fe 2p XPS spectra, presented in Figure , exhibit two peaks corresponding to 2p 1/2 and 2p 3/2 due to spin multiplet splitting. − Peaks at approximately 709.722 eV represent Fe 2+ , while those around 711.725 eV indicate Fe 3+ due to multiple splitting. As the influence of the Fe 3+ peak increases, it can be observed through Figure a,d that the Fe 2p 1/2 and 2p 3/2 peaks shift to the right or split.…”

Section: Resultsmentioning

confidence: 99%

Exploring Structural Features and Growth Mechanisms in GdBa₂Cu₃O_7–x/LaFeO₃ Bilayers on SrTiO₃ Substrates

Park,

Oh,

Kang

2024

ACS Omega

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This study investigated a novel approach to enhance the performance of superconductors by applying a LaFeO 3 (LFO) buffer layer on a GdBa 2 Cu 3 O 7−x (GdBCO) superconducting thin film. LFO is a rare-earth orthoferrite (REFO) materials. The objective was to assess how the thickness of the LFO layer influences the superconducting properties of the GdBCO material. LFO layers were fabricated at thicknesses of 50, 100, 150, and 200 nm, and subsequently, a 200 nm thick layer of GdBCO was deposited to create a bilayer structure. This study represents the first utilization of a REFO material, specifically LFO, as a buffer layer, with findings showing its growth in a pseudocubic structure. We thoroughly examined the characteristics of LFO, including its structural, surface, and strain states, focusing on the impact of varying layer thicknesses. Additionally, we investigated changes within the GdBCO/LFO bilayer and analyzed how LFO influences the properties of GdBCO. It was found that the application of the LFO buffer layer by varying thicknesses not only provided structural compatibility with GdBCO but also consistently resulted in the improvement of its superconducting transition temperature, as evidenced by the enhanced Tc-onset values reaching up to 92.4 K with an LFO thickness of 150 nm. These findings reveal significant potential in utilizing REFO materials, particularly those derived from LFO, as effective buffer layers in superconductor applications.

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“…Two‐dimensional (2D) catalysts have ultra‐high atom utilization and unique catalytic performance due to their special structure, [31,32] which helps alleviate the scarcity and expense of Ir. Furthermore, the thickness of the 2D catalyst greatly affects the catalytic performance [33,34] . Because the adsorption/desorption kinetics of intermediate components are largely affected by the surface structure of the catalyst, building the catalyst surface structure at the atomic level has become an efficient strategy to further improve their catalytic performance [35,36] .…”

Section: Figurementioning

confidence: 99%

“…Furthermore, the thickness of the 2D catalyst greatly affects the catalytic performance. [33,34] Because the adsorption/desorption kinetics of intermediate components are largely affected by the surface structure of the catalyst, building the catalyst surface structure at the atomic level has become an efficient strategy to further improve their catalytic performance. [35,36] Different from crystalline materials with long-range order, amorphous materials have only short-range periodicity, which endows them with unique properties.…”

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confidence: 99%

Two‐Dimensional Amorphous Iridium Oxide for Acidic Oxygen Evolution Reaction

Liao

Zhu

et al. 2023

ChemCatChem

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The increasing popularity of proton exchange membrane electrolysis technology for hydrogen production has brought attention to the electrolytic water reaction. However, the slow kinetics of the oxygen evolution reaction (OER) at the anode have great influence on the overall efficiency of the reaction. While iridium oxide shows excellent stability under acidic conditions, its OER activity still needs to be improved. Here, we synthesized two‐dimensional amorphous iridium oxide (Am‐IrO2) nanosheets with the thickness of only 6 nm by a mixed molten salt method. Such nanosheets show an ultralow overpotential of only 230 mV at 10 mA cm‐2 in 0.5 M H2SO4. The overpotential increases only 40 mV after 90 hours of the stability test at this current density. Am‐IrO2 can maintain the current density of ~400 mA cm‐2 after 120 hours of test at 1.8 V in the PEM device, demonstrating good industrial prospects. Density functional theoretical calculations show that the oxygen vacancies, together with the upshift of the O 2p band center, are responsible for the improvement of OER in Am‐IrO2.

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Thickness dependent OER electrocatalysis of epitaxial LaFeO₃ thin films

Abstract: Transition metal oxides have long been an area of interest for water electrocatalysis through the oxygen evolution and oxygen reduction reactions. Iron oxides, such as LaFeO3, are particularly promising due...

Cited by 19 publications

References 36 publications

Activity-Stability Relationships in Oxide Electrocatalysts for Water Electrolysis

Activity-Stability Relationships in Oxide Electrocatalysts for Water Electrolysis

Exploring Structural Features and Growth Mechanisms in GdBa₂Cu₃O_7–x/LaFeO₃ Bilayers on SrTiO₃ Substrates

Two‐Dimensional Amorphous Iridium Oxide for Acidic Oxygen Evolution Reaction

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Thickness dependent OER electrocatalysis of epitaxial LaFeO3 thin films

Abstract: Transition metal oxides have long been an area of interest for water electrocatalysis through the oxygen evolution and oxygen reduction reactions. Iron oxides, such as LaFeO3, are particularly promising due...

Cited by 19 publications

References 36 publications

Activity-Stability Relationships in Oxide Electrocatalysts for Water Electrolysis

Activity-Stability Relationships in Oxide Electrocatalysts for Water Electrolysis

Exploring Structural Features and Growth Mechanisms in GdBa2Cu3O7–x/LaFeO3 Bilayers on SrTiO3 Substrates

Two‐Dimensional Amorphous Iridium Oxide for Acidic Oxygen Evolution Reaction

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Thickness dependent OER electrocatalysis of epitaxial LaFeO₃ thin films

Exploring Structural Features and Growth Mechanisms in GdBa₂Cu₃O_7–x/LaFeO₃ Bilayers on SrTiO₃ Substrates