Development of Cathodic Silence in an Oxide Film on a Gold Electrode

Giron, Rachel Guia P.; Ferguson, Gregory S.

doi:10.1016/j.electacta.2015.08.152

Cited by 10 publications

(22 citation statements)

References 33 publications

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Section: Discussionmentioning

confidence: 99%

“…Depending on the chosen resting potential, the time required to reduce the surface oxide ranges from several seconds to minutes (Figure A, Figures S7 and S8). This observation is in agreement with the literature where the Au oxide reduction reaction has been reported to occur on a broad window of time scales from μs to minutes depending on the applied electrode potential. ,,, …”

Section: Discussionmentioning

confidence: 99%

“…This observation is in agreement with the literature where the Au oxide reduction reaction has been reported to occur on a broad window of time scales from μs to minutes depending on the applied electrode potential. 6,46,56,57 EC-SER spectra always represent an ensemble response from multiple SERS-hotspots at the surface. 58 The observed temporal evolution of the spectra is therefore an average signature of the surface reactivity during the AuOx reduction.…”

Section: Discussionmentioning

confidence: 99%

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Role of OH Intermediates during the Au Oxide Electro-Reduction at Low pH Elucidated by Electrochemical Surface-Enhanced Raman Spectroscopy and Implicit Solvent Density Functional Theory

et al. 2020

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Molecular understanding of the electrochemical oxidation of metals and the electro-reduction of metal oxides is of pivotal importance for the rational design of catalyst-based devices where metal(oxide) electrodes play a crucial role. Operando monitoring and reliable identification of reacting species, however, are challenging tasks because they require surface-molecular sensitive and specific experiments under reaction conditions and sophisticated theoretical calculations. The lack of molecular insight under operating conditions is largely due to the limited availability of operando tools and to date still hinders a quick technological advancement of electrocatalytic devices. Here, we present a combination of advanced density functional theory (DFT) calculations considering implicit solvent contributions and time-resolved electrochemical surface-enhanced Raman spectroscopy (EC-SERS) to identify short-lived reaction intermediates during the showcase electro-reduction of Au oxide (AuOx) in sulfuric acid over several tens of seconds. The EC-SER spectra provide evidence for temporary Au-OH formation and for the asynchronous adsorption of (bi)sulfate ions at the surface during the reduction process. Spectral intensity fluctuations indicate an OH/(bi)sulfate turnover period of 4 s. As such, the presented EC-SERS potential jump approach combined with implicit solvent DFT simulations allows us to propose a reaction mechanism and prove that short-lived Au-OH intermediates also play an active role during the AuOx electro-reduction in acidic media, implying their potential relevance also for other electrocatalytic systems operating at low pH, like metal corrosion, the oxidation of CO, HCOOH, and other small organic molecules, and the oxygen evolution reaction.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Role of OH Intermediates during the Au Oxide Electro-Reduction at Low pH Elucidated by Electrochemical Surface-Enhanced Raman Spectroscopy and Implicit Solvent Density Functional Theory

et al. 2020

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“…Prior to anodization, the gold electrodes were cleaned chemically by immersing in weak aqua regia (0.5-M HNO 3 , 1.5-M HCl) solution for 5 min 29,30 and then cleaned electrochemically in deaerated 0.5-M H 2 SO 4 under a N 2 blanket by cycling the applied potential seven times between −0.2 to +1.2 V at 0.1 V/s. An oxide layer, with an ellipsometric thickness of 0.9 ± 0.1 nm, was produced by sweeping the potential linearly from −0.3 to +1.2 V at a rate of 0.1 V/s, and then holding it at 1.2 V for 5 min.…”

Section: Methodsmentioning

confidence: 99%

“…4 We have examined several of these issues in light of our recent discovery that: (1) loss of the oxide film in absence of an applied potential is abrupt rather than gradual; and (2) the oxide becomes inaccessible to reduction by linear sweep voltammetry (LSV) while in contact with aqueous H 2 SO 4 . 29,30 We refer to this loss of response by the film to voltammetric analysis as "cathodic silence" because although the oxide can no longer communicate with the circuit, measurement of both the thickness, by ellipsometry, and mass, by electrochemical quartzcrystal gravimetry (EQCM), revealed that it is still present. Further, comparison of the ellipsometric and EQCM data in these studies indicate that when the circuit is opened after anodization, bisulfate ions are released and gradually diffuse out of the pores of the β-oxide.…”

mentioning

confidence: 99%

Interfacial Redox Properties of Gold/Gold Oxide in the Presence and Absence of Applied Potential

Giron¹,

Ferguson²

2019

J. Electrochem. Soc.

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Although gold does not form a native oxide under ordinary conditions, its surface can be oxidized electrochemically and the resulting oxide film studied. We have used this approach to examine the effects of anodization potential, anodization time, pH, and presence or absence of dissolved oxygen on the open-circuit decomposition of anodic gold oxide using a combination of in situ ellipsometric, potentiometric, coulometric, and microgravimetric measurements. As expected, increasing the anodization time or potential resulted in more inert films that persisted for longer times in the absence of an applied potential. We also found that this decomposition was faster at low and high pH, but slow at neutral pH. Decomposition of the oxide film was also inhibited by the presence of dissolved oxygen in the contacting electrolyte solution.

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Electrochemical dating of archaeological gold based on refined peak current determinations and Tafel analysis

Doménech‐Carbó

Scholz

Brauns

et al. 2020

Electrochimica Acta

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Development of Cathodic Silence in an Oxide Film on a Gold Electrode

Cited by 10 publications

References 33 publications

Role of OH Intermediates during the Au Oxide Electro-Reduction at Low pH Elucidated by Electrochemical Surface-Enhanced Raman Spectroscopy and Implicit Solvent Density Functional Theory

Role of OH Intermediates during the Au Oxide Electro-Reduction at Low pH Elucidated by Electrochemical Surface-Enhanced Raman Spectroscopy and Implicit Solvent Density Functional Theory

Interfacial Redox Properties of Gold/Gold Oxide in the Presence and Absence of Applied Potential

Electrochemical dating of archaeological gold based on refined peak current determinations and Tafel analysis

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