Anodic dissolution and reordering of Pd(110) induced by chemisorbed iodine

Temesghen, Woldegabr; Abreu, Juan B.; Barriga, Raul J.; Lafferty, Evelyn A.; Soriaga, Manuel P.; Sashikata, K.; Itaya, Kingo

doi:10.1016/s0039-6028(97)00229-x

Cited by 14 publications

(8 citation statements)

References 20 publications

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“…7 A similar scenario was observed for iodine on Cu(110), where the quasi hexagonal phase was observed at ∼0.67 ML co-existing with an ordered CuI phase. The quasi hexagonal phase was explained by a compression of the iodine layer along the −110 direction.…”

Section: Introductionsupporting

confidence: 66%

Surface concentration dependent structures of iodine on Pd(110)

Göthelid

Tymczenko

Chow

et al. 2012

The Journal of Chemical Physics

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We use photoelectron spectroscopy, low energy electron diffraction, scanning tunneling microscopy, and density functional theory to investigate coverage dependent iodine structures on Pd(110). At 0.5 ML (monolayer), a c(2 × 2) structure is formed with iodine occupying the four-fold hollow site. At increasing coverage, the iodine layer compresses into a quasi-hexagonal structure at 2/3 ML, with iodine occupying both hollow and long bridge positions. There is a substantial difference in electronic structure between these two iodine sites, with a higher electron density on the bridge bonded iodine. In addition, numerous positively charged iodine near vacancies are found along the domain walls. These different electronic structures will have an impact on the chemical properties of these iodine atoms within the layer.

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Section: Introductionsupporting

confidence: 66%

Surface concentration dependent structures of iodine on Pd(110)

Göthelid

Tymczenko

Chow

et al. 2012

The Journal of Chemical Physics

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“…Layer-by-layer dissolution and electrocrystallization, mediated by kink propagation, has been experimentally observed on copper surfaces covered with chloride and bromide adlayers. − Similar phenomena are seen broadly for other metal–adsorbate combinations, including Au, Ni, Ag, and Pd surfaces with surface adsorbates including halides and sulfur. ,− Uniquely, these processes appear to be primarily controlled by facet-dependent surface thermodynamics, rather than by solution-phase chemistry related to specific product speciation. ,, …”

Section: Resultsmentioning

confidence: 74%

“…16,52−56 Uniquely, these processes appear to be primarily controlled by facet-dependent surface thermodynamics, rather than by solution-phase chemistry related to specific product speciation. 17,57,58 For Cu(100)-c(2 × 2)Cl, high-speed STM imaging has shown that dissolution initiates preferentially at corners produced by the intersection of S 2 and S 2 ′ steps. 14 Dissolution at small overpotentials then preferentially propagates along the S 2 step (out-of-phase) while the S 2 ′ step (in-phase) does not react.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Halide-Induced Step Faceting and Dissolution Energetics from Atomistic Machine Learned Potentials on Cu(100)

2020

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Adsorbates impact the surface stability and reactivity of metallic electrodes, affecting the corrosion, dissolution, and deposition behavior. Here, we use density functional theory (DFT) and DFT-based Behler−Parrinello neural networks (BPNN) to investigate the geometry, surface formation energy, and atom removal energy of stepped and kinked surfaces vicinal to Cu(100) with a c(2 × 2) Cl adlayer.DFT calculations indicate that the stable structures for the adsorbate-free vicinal surfaces favor steps with ⟨110⟩ orientation, while the addition of a c(2 × 2) Cl adlayer leads to ⟨100⟩ step faceting, in agreement with scanning tunneling microscopy (STM) observations. The BPNN calculations produce energies in good agreement with DFT results (root-mean-square error of 1.3 meV/atom for a randomly chosen set of structures excluded from the training set). We draw three conclusions from the BPNN calculations. First, Cl on the upper ⟨100⟩ step edges occupies the 3-fold hollow sites (as opposed to the 4-fold sites on the terraces), congruent with deviations of the STM height profile for the adsorbate at the upper step edge. Second, disruptions in the continuity of the halide overlayer at the steps result in significant long-range step−step interactions. Third, anisotropic metal dissolution and deposition energetics arise from phase shifts of the c(2 × 2) adlayer at orthogonal ⟨100⟩ steps. This DFT-BPNN approach offers an effective strategy for tackling large-scale surface structure challenges with atomic-level accuracy.

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“…7, 8 In this paper, we present results based upon EC-STM that extend the detail of information known about adsorbatecatalyzed anodic dissolution, a relatively under-studied interfacial phenomenon, in which the corrosion of a metal substrate is induced by a single monolayer of certain adsorbates in a solution devoid of corrosion promoters. [9][10][11][12] The case under scrutiny is the dissolution of Pd single-crystal electrodes in halide-free sulfuric acid solutions catalyzed by a single adsorbed layer of zero-valent iodine atoms. [10][11][12] Initial structural work, based upon tandem UHV spectroscopy [lowenergy electron diffraction (LEED) and Auger electron spectroscopy (AES)] and electrochemistry of oriented Pd bulk single crystals, revealed that (i) the structure and composition of the iodine adlattices formed at Pd(111) 10 and Pd(100) 11 were preserved even after prolonged dissolution and (ii) progressive disorder of the Pd(110)-I 12 interface is brought about by the dissolution reaction despite the fact that the iodine coverage is unaltered.…”

Section: Introductionmentioning

confidence: 99%

“…12 The formation of these pits is simply due to the dissolution of more active Pd atoms on the Pd(110) terraceplane. In view of the aggressive reactivity of the Pd(110)-I surface relative to Pd(111)-I and Pd(100)-I (Figure 3), it may just be that pit corrosion on Pd(110)-I terraces cannot be completely eliminated.…”

mentioning

confidence: 99%

Adsorbed-Iodine-Catalyzed Dissolution of Pd Single-Crystal Electrodes: Studies by Electrochemical Scanning Tunneling Microscopy

Sashikata¹,

Matsui²,

Itaya³

et al. 1996

J. Phys. Chem.

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102

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Unfettered anodic dissolution occurs in halide-free sulfuric acid solutions for Pd electrodes pretreated with a single chemisorbed layer of iodine atoms; no dissolution takes place in the absence of iodine. Tandem cyclic voltammetry and in situ scanning tunneling microscopy have been employed to investigate the mechanism of this type of corrosion under low-current conditions. The ordered adlattices studied were those spontaneously formed upon immersion of the Pd single-crystal surface to a dilute solution of iodide: Pd(111)-( 3 × 3)-R30°-I; Pd(100)-c(2 × 2)-I; Pd(110)-pseudohexagonal-I. It has been found that (i) adsorbed-iodine-catalyzed corrosion of Pd is a structure-sensitive reaction; it decreases in the order Pd(110)-I > Pd(111)-I g Pd(100)-I. (ii) At Pd(111)-I, dissolution occurs exclusively at step-edges in a layer-by-layer sequence without deterioration of the iodine adlattice structure. (iii) At Pd(100)-I, dissolution takes place anisotropically along a step aligned in the {100} direction but in a layer-by-layer process without disruption of the iodine adlattice structure. (iv) At Pd(110)-I, dissolution transpires predominantly at a step-edge that runs parallel to the {100} direction; pit formation at terraces precluded layer-by-layer dissolution and led to progressive disorder of the substrate structure. Heuristic models are presented to account for these observations.

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Anodic dissolution and reordering of Pd(110) induced by chemisorbed iodine

Cited by 14 publications

References 20 publications

Surface concentration dependent structures of iodine on Pd(110)

Surface concentration dependent structures of iodine on Pd(110)

Halide-Induced Step Faceting and Dissolution Energetics from Atomistic Machine Learned Potentials on Cu(100)

Adsorbed-Iodine-Catalyzed Dissolution of Pd Single-Crystal Electrodes: Studies by Electrochemical Scanning Tunneling Microscopy

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