Density functional theory study on the effect of OH and Cl adsorption on the surface structure of α-Fe2O3

Pang, Qin; DorMohammadi, H.; Isgor, O. Burkan; Árnadóttir, Líney

doi:10.1016/j.comptc.2016.12.009

Cited by 25 publications

(12 citation statements)

References 56 publications

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“…E ad decreases by 0.09 eV in the range of OH coverages considered [figure 4(a)] to 2.19 eV for 1/3 ML. This agrees well with recent PBE+U result (2.31 eV [19]). Adsorption energies calculated by using PBE+U+D3, i.e.…”

Section: Oh Adsorptionsupporting

confidence: 94%

“…Stability of two hydroxylated, iron and oxygen terminated surfaces has been studied using surface-specific DFT+U approach [18]. The effects of OH adsorption at different coverages on the structure of Fe-terminated α-Fe 2 O 3 (0001) surface was also studied [19]. Calculations of Negreiros et al [20], including the van der Waals correction, of the interaction of very low coverage of water with this surface, showed that a negatively charged surface reduces the energy barrier and enhances substantially the water binding and inhibits water dissociation.…”

Section: Introductionmentioning

confidence: 99%

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Incipient adsorption of water and hydroxyl on hematite (0001) surface

Pabisiak

Kiejna

2019

J. Phys. Commun.

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The adsorption of submonolayer coverages of water and hydroxyl molecules on hematite (0001) surface is investigated using density functional theory with Hubbard correction U (DFT+U). The effect of adsorption on the structural, energetic, and electronic properties of both iron and oxygen terminated hematite surfaces is examined. The influence of the van der Waals interactions on the adsorption binding energy and geometry is also considered. It is found that tilted orientations of molecules are energetically more favored than planar ones, because the hydrogen bond stabilizes molecules on the surface. Bonding of H 2 O is more than twice weaker than that of OH. For both molecules adsorption on the iron-rich termination is much stronger than on the oxygen-terminated surface. The differences in bonding properties of water and hydroxyl molecules to the hematite surfaces are explained by different character of the charge transfer in the molecule-oxide system.

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Section: Oh Adsorptionsupporting

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Incipient adsorption of water and hydroxyl on hematite (0001) surface

Pabisiak

Kiejna

2019

J. Phys. Commun.

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“…Atomistic modeling techniques, such as reactive force field molecular dynamics (ReaxFF-MD) [33][34][35][36][37][38][39][40][41][42] and density functional theory (DFT), [43][44][45][46][47][48] have shown great potential to provide answers to such questions. In particular, ReaxFF-MD has emerged as a simulation framework to investigate reactive processes at spatial scales of nm 2 that can be correlated to physical systems.…”

Section: Introductionmentioning

confidence: 99%

Investigation of chloride-induced depassivation of iron in alkaline media by reactive force field molecular dynamics

et al. 2019

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The passivity of iron in alkaline media enables the use of carbon steel as reinforcement in concrete, which makes up the majority of modern infrastructure. However, chlorides, mainly from deicing chemicals or marine salts, can break down the iron passive film and cause active corrosion. Despite recent advances in nanoscale characterization of iron passivity, significant gaps exist in our understanding of the dynamic processes that lead to the chloride-induced breakdown of passive films. In this study, chlorideinduced depassivation of iron in pH 13.5 NaOH solution is studied using reactive force field molecular dynamics. The depassivation process initiates by local acidification of the electrolyte near the film surface, followed by iron dissolution into the electrolyte, and iron vacancy formation in the passive film. Chlorides do not penetrate the passive film, but mainly act as a catalyst for the formation of iron vacancies, which diffuse toward the metal/oxide interface, suggesting a depassivation mechanism consistent with the pointdefect model.

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“…The lattice constants for the unit cell of α-Fe 2 O 3 are optimized as a = b = 5.027 Å and c = 13.724 Å (c/a = 2.73) in this study, in good agreement with experimental values (a = b = 5.035 Å and c = 13.747 Å) 34 . The magnetic state for of α-Fe 2 O 3 is applied as antiferromagnetic (+ + − −) based on our previous study 29 . More information regarding properties of α-Fe 2 O 3 and surface structure can be found elsewhere 8,9,29 .…”

Section: Methodsmentioning

confidence: 99%

“…The magnetic state for of α-Fe 2 O 3 is applied as antiferromagnetic (+ + − −) based on our previous study 29 . More information regarding properties of α-Fe 2 O 3 and surface structure can be found elsewhere 8,9,29 .…”

Section: Methodsmentioning

confidence: 99%

Thermodynamic feasibility of the four-stage chloride-induced depassivation mechanism of iron

et al. 2020

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The atomistic mechanism of chloride-induced depassivation of iron is still debated. A recent study suggests a four-stage depassivation mechanism, in general agreement with the point defect model. The proposed four-stage mechanism is based on reactive force field molecular dynamics simulations and is rather complex but here we use density functional theory to confirm the thermodynamic feasibility of the proposed mechanism. We find that the four surface species, formed in the four stages, have decreasing surface stability, which is consistent with the order of species formed in the depassivation process proposed in the reactive force field molecular dynamics study. The Fe vacancy formation energy, that is the energy needed to form a surface Fe vacancy by removing different surface species, indicates that surface species with more chlorides dissolve more easily from the surface, suggesting that chloride acts as catalyst in the iron dissolution process. The results are consistent with the suggested fourstage reaction mechanism and the point defect model.

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Density functional theory study on the effect of OH and Cl adsorption on the surface structure of α-Fe2O3

Cited by 25 publications

References 56 publications

Incipient adsorption of water and hydroxyl on hematite (0001) surface

Incipient adsorption of water and hydroxyl on hematite (0001) surface

Investigation of chloride-induced depassivation of iron in alkaline media by reactive force field molecular dynamics

Thermodynamic feasibility of the four-stage chloride-induced depassivation mechanism of iron

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