High resolution electrochemical STM: New structural results for underpotentially deposited Cu on Au(111) in acid sulfate solution

Vasiljević, Nataša; Viyannalage, L. T.; Dimitrov, Nikolay; Sieradzki, Karl

doi:10.1016/j.jelechem.2007.10.021

Cited by 18 publications

(16 citation statements)

References 34 publications

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“…The profiles are similar to those found in the literature, where the UPD of Cu ions on Au electrodes have been revisited many times along the last decades both, using pure electrochemical experiments 28,29 and multi-technique approaches [30][31][32][33][34][35] . Thus, valuable information was obtained through experiments involving single crystal electrodes in acid media using X-rays absorption and diffraction techniques in synchrotron facilities and Scanning Tunnelling Microscopy in situ.…”

Section: Resultssupporting

confidence: 82%

Standard Underpotential Deposition Shift. A New Parameter to Characterize the UPD Phenomenon.

Vicente¹,

Gomes²,

Fernández

2021

Preprint

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Underpotential deposition (UPD) is a phenomenon where atoms of an element M are deposited from ions Mn+ on a substrate S at potentials more positive than for the deposition of Mn+ on M. These systems have been studied for more than a century and are interesting from both the applied and the fundamental point of view. Despite the vast literature on the subject, there is no thermodynamic parameter so far able to characterize an UPD system. Even if the so-called “UPD shift” has been used for decades, the limitations of this parameter has been fully recognized in the field. Herein, using a simple Nernstian treatment and straightforward measurements, we show how to measure and calculate a new proposed fundamental thermodynamic parameter namely, the “Standard UPD potential”. We showed results for the deposition of Cu+2 on Au in acidic media, in solutions containing ClO4- or SO4-2 anions. We obtained Standard UPD potential= 0.65 ± 0.02 V, independently of the concentration of the acid and the nature of the anion.

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Section: Resultssupporting

confidence: 82%

Standard Underpotential Deposition Shift. A New Parameter to Characterize the UPD Phenomenon.

Vicente¹,

Gomes²,

Fernández

2021

Preprint

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“…It must be pointed out that the interpretation of the phase transitions taking place in this system, responsible for the two couples of peaks mentioned, is considerably more involved [202][203][204]164] than that given above in terms of the monatomic gas lattice model. The occurrence of islands corresponding to the different phases has been confirmed in various articles [135][136][137]. These systems also present relatively sharp voltammetric peaks, although the less negative pair presents always the larger irreversibility.…”

Section: ð3:54þmentioning

confidence: 67%

“…[164,192] which is transformed into a (1 Â 1) Cu structure at lower potentials [162]. Recent experiments, however, point out towards the occurrence of an ordered sulfate p(2 Â 2) [136] or ffiffi ffi [193] structure on the pseudomorphic Cu(1 Â 1) upd layer Addition of Cl À generates, depending on its concentration, a (2 Â 2) or an incommensurate "(5 Â 5)" structure [137] X-ray absorption experiments suggest that copper and coadsorbed chloride form a bilayer in which copper atoms are sandwiched in-between the top chloride and the bottom gold layers [34] Pt(111)/Ag Ag upd peak does not follow the Nernstian behavior of 60 mV shift per decade change in cation concentration expected [153] Radimoetric measurements show that adsorption of bisulfate is higher on silver-covered platinum than on the clean platinum substrate [194] …”

Section: ð3:54þmentioning

confidence: 99%

Phenomenology and Thermodynamics of Underpotential Deposition

Oviedo

Reinaudi

García

et al. 2015

Underpotential Deposition

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As can be found from the other chapters of this book, underpotential deposition shows a wide variety of behaviors, which involve the occurrence of several surface phases, formation of submonolayers, monolayers (ML) and eventually the formation of bilayers. Adsorption may be commensurate or incommensurate, where the ML may undergo compression, and metal adatoms may coadsorb with anions to generate new phases. To start the discussion and briefly go into the history of the development of thermodynamic models for upd, we consider a relatively "simple" system, as shown in Fig. 3.1, which corresponds to Ag deposition on Pt(111) [1]. The voltammogram of this system presents three cathodic and three anodic peaks, which correspond to ML formation/desorption(3), bilayer formation/desorption(2) and bulk deposition/oxidation(1) of Ag. The peak potentials of the complementary processes do not coincide, denoting that at the present sweep rate a quasi equilibrium state has still not been reached. For the discussion below, we choose the anodic peaks, that we will denote with E 1 , E 2 and E 3 (see Fig. 3.1). At the sight of the features of this voltammogram, and although the abscissa axis gives a measure for the electrochemical potential of electrons at the working electrode, it may be appealing to use the position of the peaks found for this system as a measure for the stability of the different upd ad-phases being formed. In this spirit, Kolb et al. [2][3][4] introduced in the 1970s the concept of underpotential shift, ΔE upd . This quantity was defined as the difference in the potential of the desorption peak for a layer of a metal M adsorbed on a foreign substrate S and the potential of the peak corresponding to the dissolution of the pure metal M. In the present case, ΔE upd ¼ E 3 À E 1 , as marked in the red segment in Fig. 3.1. At the time Kolb et al. developed their modeling of upd, single crystal surfaces were not available for performing electrochemical experiments, so that all the data employed by these authors were restricted to polycrystalline surfaces. On the basis

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“…[28][29][30][31][32] The various adlayer structures were characterized by electron diffraction, 33,34 X-ray techniques, 24,29,[35][36][37][38][39][40] infrared absorption 26,[40][41][42][43] and Auger electron 44 spectroscopies as well as by electrochemical STM [45][46][47][48][49][50][51][52][53][54] and atomic force microscopy (AFM). 55,56 The experimental studies are complemented by theoretical modelling employing statistical mechanics, Monte Carlo simulations, density functional and/or molecular dynamics approaches.…”

Section: -16mentioning

confidence: 99%

Structure transitions between copper-sulphate and copper-chloride UPD phases on Au(111)

2009

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Abstract. Structure transitions between copper UPD adlayers on Au(111)-(1 × 1) in sulfuric acid and chloride containing electrolyte were investigated by in situ scanning tunnelling microscopy. We demonstrate that co-adsorbed sulphate ions in the (√3 × √3)R30° UPD adlayer are replaced by chloride ions and, depending on the halide coverage, a commensurate (2 × 2) or a slightly distorted (5 × 5)-like Cu-Cl UPD adlayer are formed. The stability ranges of these phases are controlled both by the electrode potential and the Cl -concentration. Phase transitions between the three UPD phases were monitored by time-resolved in situ STM. The observed structure details were attributed to mechanisms based on two-dimensional nucleation and growth processes.

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High resolution electrochemical STM: New structural results for underpotentially deposited Cu on Au(111) in acid sulfate solution

Cited by 18 publications

References 34 publications

Standard Underpotential Deposition Shift. A New Parameter to Characterize the UPD Phenomenon.

Standard Underpotential Deposition Shift. A New Parameter to Characterize the UPD Phenomenon.

Phenomenology and Thermodynamics of Underpotential Deposition

Structure transitions between copper-sulphate and copper-chloride UPD phases on Au(111)

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