Structure and ordering of oxygen on unreconstructed Ir(100)

Ferstl, Pascal; Schmitt, Thorsten; Schneider, M. Alexander; Hammer, Lutz; Michl, Anja; Müller, Stefan

doi:10.1103/physrevb.93.235406

Cited by 20 publications

(28 citation statements)

References 44 publications

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“…by assuming either all sites or only every second one in a 3×2 cell (Table I top). As for the bare Ir(100)-1×1 surface the Ir bridge site is energetically preferred over hollow site adsorption and there is also a clear preference for nearest neighbor site occupation (0.11 eV energy gain per oxygen) leading to oxygen chain formation 42 . In contrast, the Ir hollow site shows an enormous nearest neighbor repulsion leading to a 0.42 eV reduction of the binding energy, when filling up all sites.…”

Section: Energetics Of the Cobalt Oxide Chain Phasesmentioning

confidence: 99%

Monatomic Co, CoO2 , and CoO3 nanowires on Ir(100) and Pt(100) surfaces: Formation, structure, and energetics

et al. 2017

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In this study we investigate the structural and chemical changes of monatomic CoO2 chains grown self-organized on the Ir(100) surface [P. Ferstl et al., PRL 117, 2016, 046101] and on Pt(100) under reducing and oxidizing conditions. By a combination of quantitative low-energy electron diffraction, scanning tunnelling microscopy, and density functional theory we show that the cobalt oxide wires are completely reduced by H2 at temperatures above 320 K and a 3×1 ordered Ir2Co or Pt2Co surface alloy is formed. Depending on temperature the surface alloy on Ir (100) is either hydrogen covered (T < 400 K) or clean and eventually undergoes an irreversible order-disorder transition at about 570 K. The Pt2Co surface alloy disorders with the desorption of hydrogen, whereby Co submerges into subsurface sites. Vice versa, applying stronger oxidants than O2 such as NO2 leads to the formation of CoO3 chains on Ir(100) in a 3×1 superstructure. On Pt(100) such a CoO3 phase could not be prepared so far, which however, is due to the UHV conditions of our experiments. As revealed by theory this phase will become stable in a regime of higher pressure. In general, the structures can be reversibly switched on both surfaces using the respective agents O2, NO2 and H2.

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Section: Energetics Of the Cobalt Oxide Chain Phasesmentioning

confidence: 99%

Monatomic Co, CoO2 , and CoO3 nanowires on Ir(100) and Pt(100) surfaces: Formation, structure, and energetics

et al. 2017

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“…Experimentally, we first characterized Co 3 O 4 (111) thin films prepared on a Ir(100)-(2 × 1)O/Ir(100)-(3 × 1)O substrate (d Co3O4 � 9-12 nm) by STM and XPS measurements ( Figure 3) (details about the structure of oxygen on the Ir substrate can be found in refs. [68][69]). Our XPS measurements of Co 2p spectra were carried out at an emission angles of 0°with respect to the surface normal.…”

Section: Structure and Composition Of The Co 3 O 4 (111) Filmsmentioning

confidence: 99%

Model Studies on the Formation of the Solid Electrolyte Interphase: Reaction of Li with Ultrathin Adsorbed Ionic‐Liquid Films and Co₃O₄(111) Thin Films

et al. 2021

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In this work we aim towards the molecular understanding of the solid electrolyte interphase (SEI) formation at the electrode electrolyte interface (EEI). Herein, we investigated the interaction between the battery‐relevant ionic liquid (IL) 1‐butyl‐1‐methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP‐TFSI), Li and a Co3O4(111) thin film model anode grown on Ir(100) as a model study of the SEI formation in Li‐ion batteries (LIBs). We employed mostly X‐ray photoelectron spectroscopy (XPS) in combination with dispersion‐corrected density functional theory calculations (DFT‐D3). If the surface is pre‐covered by BMP‐TFSI species (model electrolyte), post‐deposition of Li (Li+ ion shuttle) reveals thermodynamically favorable TFSI decomposition products such as LiCN, Li2NSO2CF3, LiF, Li2S, Li2O2, Li2O, but also kinetic products like Li2NCH3C4H9 or LiNCH3C4H9 of BMP. Simultaneously, Li adsorption and/or lithiation of Co3O4(111) to LinCo3O4 takes place due to insertion via step edges or defects; a partial transformation to CoO cannot be excluded. Formation of Co0 could not be observed in the experiment indicating that surface reaction products and inserted/adsorbed Li at the step edges may inhibit or slow down further Li diffusion into the bulk. This study provides detailed insights of the SEI formation at the EEI, which might be crucial for the improvement of future batteries.

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“…1,10,19 Unlike extensive computational research on Pt, atomistic modeling studies of Ir in aqueous environments are still very limited. 20,[20][21][22] Experimental investigations, however, demonstrate that significant differences in electrochemical behavior of the two noble metals can be observed. For example, Ir exhibits higher OER activity than Pt, but it also corrodes faster.…”

Section: Introductionmentioning

confidence: 99%

Ab Initio Thermodynamics of Iridium Surface Oxidation and Oxygen Evolution Reaction

2018

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Iridium-based materials are considered as state-of-the-art electrocatalysts for oxygen evolution reaction (OER), however, their stability and catalytic activity greatly depend on surface-state changes induced by electrochemical cycling. To better understand the behavior of the low-index Ir surfaces in an electrochemical environment, we perform a systematic thermodynamic analysis by means of the density functional theory (DFT) calculations. Based on computed surface energies of the Ir(111), (110) and (100) facets as a function of applied electrode potential and coverage of adsorbed water species we determine stability maps and predict equilibrium shapes of Ir nanoparticles. Our calculations also show that metastable oxide precursors formed at the initial stages of Ir surface oxidation are responsible for enhanced catalytic activity towards OER as compared to metal surfaces covered by oxygen adsorbates and thick-oxide films. Such enhancement occurs not only due to the modified thermodynamic stability of OER intermediates, but also because thin-oxide layers may display the more energetically favorable I2M (interaction of two M−O units) rather than WNA (water nucleophilic attack) OER mechanism.

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Structure and ordering of oxygen on unreconstructed Ir(100)

Cited by 20 publications

References 44 publications

Monatomic Co, CoO2 , and CoO3 nanowires on Ir(100) and Pt(100) surfaces: Formation, structure, and energetics

Monatomic Co, CoO2 , and CoO3 nanowires on Ir(100) and Pt(100) surfaces: Formation, structure, and energetics

Model Studies on the Formation of the Solid Electrolyte Interphase: Reaction of Li with Ultrathin Adsorbed Ionic‐Liquid Films and Co₃O₄(111) Thin Films

Ab Initio Thermodynamics of Iridium Surface Oxidation and Oxygen Evolution Reaction

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Structure and ordering of oxygen on unreconstructed Ir(100)

Cited by 20 publications

References 44 publications

Monatomic Co, CoO2 , and CoO3 nanowires on Ir(100) and Pt(100) surfaces: Formation, structure, and energetics

Monatomic Co, CoO2 , and CoO3 nanowires on Ir(100) and Pt(100) surfaces: Formation, structure, and energetics

Model Studies on the Formation of the Solid Electrolyte Interphase: Reaction of Li with Ultrathin Adsorbed Ionic‐Liquid Films and Co3O4(111) Thin Films

Ab Initio Thermodynamics of Iridium Surface Oxidation and Oxygen Evolution Reaction

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Model Studies on the Formation of the Solid Electrolyte Interphase: Reaction of Li with Ultrathin Adsorbed Ionic‐Liquid Films and Co₃O₄(111) Thin Films