Effect of thiol self-assembled monolayers and plasma polymer films on dealloying of Cu–Au alloys

Pareek, Aparna; Ankah, Genesis Ngwa; Cherevko, Serhiy; Ebbinghaus, Petra; Mayrhofer, Karl Johann Jakob; Erbe, Andreas; Renner, Frank Uwe

doi:10.1039/c3ra22970j

Cited by 17 publications

(19 citation statements)

References 56 publications

(106 reference statements)

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“…7,8 Unlike most base metals, noble metals are usually resistant toward significant oxidation and corrosion in moisture, air and most acidic and alkaline electrolytes. However, they do dissolve at positive potential excursions in parallel to surface oxidation.…”

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confidence: 99%

Effect of Temperature on Gold Dissolution in Acidic Media

Cherevko

Žeradjanin

Topalov

et al. 2014

J. Electrochem. Soc.

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Temperature has a tremendous effect on the rate and amount of gold dissolution. In potentiodynamic experiments the total amount of dissolved gold increases by a factor of 4.5 when the temperature is increased from 25 to 75 • C. Moreover, the previously reported correlation between the onset of oxide formation and the commencement of the dissolution process is found to be correct for all studied temperatures. Negative shift in the advent of oxidation is accompanied by a similar shift in the dissolution onset potential. Similarly, the dissolution rate rises significantly with temperature during potentiostatic and galvanostatic polarization steps. A correlation between the temperature-dependent oxygen evolution reaction (OER) and gold dissolution is found. Arrhenius plots for the OER and gold dissolution are used to obtain information on the apparent activation energy E A for both processes. It is found that for OER and Au dissolution E A = 57 kJ mol −1 . The later finding suggests that there is a common intermediate for both reactions, the formation of which constitutes the rate-determining step. Over the past few years, our group has published a number of papers on electrochemical dissolution of noble metals (coinage and precious) such as copper, 1 rhodium, 2 platinum, 3,4 gold 5,6 and alloys. 7,8Unlike most base metals, noble metals are usually resistant toward significant oxidation and corrosion in moisture, air and most acidic and alkaline electrolytes. However, they do dissolve at positive potential excursions in parallel to surface oxidation. The relatively low rates of noble-metal corrosion impose severe restrictions on the range of techniques which can be used to reliably investigate these processes. Nevertheless, over the last forty or fifty years, numerous approaches have been proposed, with some providing integral values on the amount of dissolved material during relatively long polarization time and others providing information on the rate of the process directly. The former are based on the post-analysis of the electrolyte by atomic absorption spectroscopy, 9 inductively coupled plasma mass spectrometry (ICP-MS), 10,11 radiotracer technique, 12,13 etc. As an example of the latter we should mention pure electrochemical methods based on comparison of oxide formation and reduction charge, 9 utilization of rotating ring disk electrodes 14,15 or double electrode flow cell [16][17][18][19][20] and coupled techniques like electrochemical quartz crystal nano(micro)balance. [21][22][23] Having extremely small detection limits, along with the ability to detect many elements over a wide linear detection range, ICP-MS is extensively utilized in different areas ranging from forensic to nuclear science. 24 Using an ICP-MS to detect traces of noble metals and coupling it directly to a so-called scanning flow cell (SFC) allowed us to extend ICP-MS applicability further; now including on-line investigation of metals dissolved during an electrochemical treatment. This technique allowed us to precisely quantify the diss...

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confidence: 99%

Effect of Temperature on Gold Dissolution in Acidic Media

Cherevko

Žeradjanin

Topalov

et al. 2014

J. Electrochem. Soc.

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“…In contrast, on homogeneously covered thiol-surfaces a stochastic distribution of dealloying sites has been described. 23 For these sites, the separation is much larger as natural structural inhomogeneity than for example the typical domain size as exemplied for a surface initially modied by a mixed aminobenzenethiol lm, 24 shown in Fig. 8b.…”

Section: Resultsmentioning

confidence: 97%

Localized dealloying corrosion mediated by self-assembled monolayers used as an inhibitor system

et al. 2015

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The structure and chemistry of thiol or selenol self-assembled organic monolayers have been frequently addressed due to the unique opportunities in functionalization of materials. Such organic films can also act as effective inhibition layers to mitigate oxidation or corrosion. Cu-Au alloy substrates covered by self-assembled monolayers show a different dealloying mechanism compared to bare surfaces. The organic surface layer inhibits dealloying of noble metal alloys by a suppression of surface diffusion at lower potentials but at higher applied potentials dealloying proceeds in localized regions due to passivity breakdown. We present an in situ atomic force microscopy study of a patterned thiol layer applied on Cu-Au alloy surfaces and further explore approaches to change the local composition of the surface layers by exchange of molecules. The pattern for the in situ experiment has been applied by micro-contact printing. This allows the study of corrosion protection with its dependence on different molecule densities at different sites. Low-density thiol areas surrounding the high-density patterns are completely protected and initiation of dealloying proceeds only along the areas with the lowest inhibitor concentration. Dealloying patterns are highly influenced and controlled by molecular thiol to selenol exchange and are also affected by introducing structural defects such as scratches or polishing defects.

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“…For Au-or Cu-based alloys, thiols and other inhibitor molecules such as the frequently used mercapto-benzimidazoles can form selfassembled monolayers (SAMs) that stabilize the surfaces and suppress surface diffusion in the corrosive environment. [49,50] Such inhibited surfaces show a changed corrosion mode from a homogenous dealloying to a heterogeneous type. To elucidate the influence of detailed inhibitor film structures, a surface science approach with a well-defined preparation of surfaces and a preadsorption of the SAMs can be applied.…”

Section: Organic Inhibitors and Controlled Localized Corrosionmentioning

confidence: 99%

“…[55] As shown in Figure 4, molecular dynamics simulations were carried out using nanoscale molecular dynamics software (NAMD [56] ) which is often chosen for large systems, and intermolecular Reproduced with permission. [50] Copyright 2013, Royal Society of Chemistry.…”

Section: Organic Inhibitors and Controlled Localized Corrosionmentioning

confidence: 99%

In Operando Atomic Force Microscopy Imaging of Electrochemical Interfaces: A Short Perspective

Neupane

Valencia-Ramírez

Losada-Pérez

et al. 2021

Physica Status Solidi (a)

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Electrochemical interfaces are at the core of many important current applications, from corrosion and biophysics to electrocatalytic and battery interfaces. Further understanding in the processes taking place at these interfaces is often linked to better observation techniques. In situ or in operando imaging and characterization of the electrochemical interface helps improve our understanding of structural sequences and kinetics of complex processes. Atomic force microscopy (AFM) offers a unique combination to monitor surface morphology and mechanical properties at micro‐ and nanoscale surfaces and solid–electrolyte interfaces. Two examples are given where the application of AFM during electrochemical processes is clearly useful. Organic inhibitors and their behavior play an important role in corrosion mitigation and the influence of thiol monolayers on dealloying is reported: Zinc films find application for coatings or Zn batteries and an in situ electrodeposition study is shortly described. With the ongoing improvement of computational simulations, the broadening of spatiotemporal scales possible with AFM imaging and its combination with mechanical information points in a prospective future for in operando AFM.

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Effect of thiol self-assembled monolayers and plasma polymer films on dealloying of Cu–Au alloys

Cited by 17 publications

References 56 publications

Effect of Temperature on Gold Dissolution in Acidic Media

Effect of Temperature on Gold Dissolution in Acidic Media

Localized dealloying corrosion mediated by self-assembled monolayers used as an inhibitor system

In Operando Atomic Force Microscopy Imaging of Electrochemical Interfaces: A Short Perspective

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