An in-situ infrared spectroscopic study of the adsorption of citrate on Au(111) electrodes

Floate, Simon; Hosseini, Mir Ghasem; Arshadi, M.; Ritson, D. M.; Young, Karen L.; Nichols, Richard J.

doi:10.1016/s0022-0728(02)01451-1

Cited by 76 publications

(93 citation statements)

References 26 publications

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“…As this absorption was not detected when the experiment was reproduced with s-polarised radiation, the 1386 cm À1 band should be attributed to the existence of a potential-induced adsorption of some species. The observed frequency lies in the spectral region characteristic of the symmetric O-C-O stretch of two-fold coordinated carboxylate anions [16][17][18][19][20] either in a bridge or on-top configuration. This finding seems fully compatible with both the chemical nature of the electrolyte employed and the voltammetric features displayed in Fig.…”

Section: Resultsmentioning

confidence: 94%

“…1 at ca. 0.5 V. In addition, from the in situ FTIR spectroscopic investigation of the Au(111)/citrate system carried out in [16] it was concluded that, in high pH electrolytes, citrate adsorbs through the carboxylate in a g-2 bonded structure. Possible bonding configurations of this adsorbate were also discussed, based on one, two or all three carboxylate groups coordinating to the Au(111) surface.…”

Section: Resultsmentioning

confidence: 99%

“…The first electrochemical in situ FTIR study of citrate on Au(111) appeared during the write-up of this paper [16]. These authors provide in depth information on the citrate-Au system in an acidic aqueous solution on a static singlecrystal electrode.…”

Section: Introductionmentioning

confidence: 99%

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Voltammetric and in situ FTIRS study on CN− and Au(CN)−x complexes at the polycrystalline gold surface in citrate medium

Huerta

Mele

Bozzini

et al. 2004

Journal of Electroanalytical Chemistry

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The adsorption and reactivity of citrate anions, cyanide anions, and the Au(I) and Au(III) cyanocomplexes (KAu(CN) 2 and KAu(CN) 4 , respectively) on gold polycrystalline electrodes have been investigated by means of cyclic voltammetry and in situ FTIR spectroscopy in pH 7 sodium citrate medium. It was found that citrate anion adsorbs reversibly through the carboxylate groups from 0.4 V (RHE) on bare gold surfaces. However, the onset of this adsorption process is shifted by 600 mV in the positive direction when adsorbed cyanide species are present at the electrode surface. The Au(I) cyanocomplex produces a film on the gold electrode that inhibits the oxidation of both citrate anions and the gold surface. The reduction of the Au(III) cyanocomplex gives rise to the formation of the Au(I) cyanocomplex at potentials less negative than those required for gold deposition. Upon reduction, both cyanocomplexes release adsorbed cyanide on the gold electrode, which can be subsequently oxidized to cyanate at higher potentials.

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Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

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Voltammetric and in situ FTIRS study on CN− and Au(CN)−x complexes at the polycrystalline gold surface in citrate medium

Huerta

Mele

Bozzini

et al. 2004

Journal of Electroanalytical Chemistry

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“…We assume the following scenario for switching events that may occur at the moleculeelectrode interface. By injecting electrons into the citrate molecule, a conformational/orientational change in the molecule is initiated, where the O-C-O group physically connecting to the gold electrode can be rotated around the C-C axis of the citrate molecule [25]. Note, depending on the bias voltage applied to the samples, the thermal energy k B T ≈ 26 meV can play an important or even dominant role in the rotation of the O-C-O group.…”

Section: Discussionmentioning

confidence: 99%

Conductance Fluctuations in Chains of Particles Arising from Conformational Changes of Stabilizer Molecules

Govor¹,

Parisi²

2013

Zeitschrift Für Naturforschung A

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We have bridged a pair of gold electrodes with various arrangements of gold nanoparticles stabilized with citrate molecules. The resulting devices exhibited current fluctuations at a constant bias voltage and fluctuations of the differential conductance as a function of the bias voltage. These fluctuations were attributed to the interplay of molecular conformation, charge switching, and breaking of the links at the interface molecules-electrode. We found that, for all investigated samples, the contact resistance at the interface molecules-electrode was by about one order of magnitude larger than that between nanoparticles coupled by citrate molecules. We conclude that the mechanism of charge transport can be viewed as a series of discrete steps involving initial hopping (injection) of the charge from the left-hand-side gold electrode to the molecules, tunnelling of the charge through the molecules-nanoparticle-molecules (MNM) unit, hopping to the next MNM unit, etc., and finally hopping (extraction) of the charge to the right-hand-side gold electrode.

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“…By injecting electrons into the citrate molecule, a conformational/orientational change in the molecule is initiated, where the O-C-O group (Fig. 4.9a), physically connecting to the gold electrode, can be rotated around the C-C axis of the citrate molecule [25]. Note that, depending on the bias voltage applied to the samples, the thermal energy k B T ≈ 26 meV can play an important or even dominant role in the rotation of the O-C-O group.…”

Section: Analysis Of the Conductivity In Chain Of Particlesmentioning

confidence: 99%

Charge Transport in Chain of Nanoparticles

Govor

Parisi

2015

Bottom-Up Self-Organization in Supramolecular Soft Matter

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We have bridged a pair of gold electrodes through chains and arrays of gold nanoparticles, coated with citrate molecules. We performed a systematic and comparative analysis of current-voltage (I − V ) characteristics for chains of nanoparticles, having variable length and configuration. The I − V characteristics I ∼ (V − V t ) ζ (with voltage threshold V t ≈ 0 and scaling exponent ζ ≈ 1) are attributed to hopping transport. Current fluctuations at a fixed bias voltage were observed, with a fluctuation amplitude proportional to the voltage applied. We found that the resistance of the bridge is not only a function of the number of molecular contacts, but also depends on the strength of the individual interactions between metal conductor and molecules. IntroductionDue to their optical and electronic properties, arrays of metallic nanoparticles (NPs) have attracted much attention in materials science. Charge transport through nanoparticle assemblies represents a fundamental process that controls their physical properties which are determined by the coupling and arrangement of individual NPs, and depend on their size, shape, and composition. Theory and experiments unveil that, at sufficiently low temperature below a threshold voltage V t , no current flows through the particle array, while above V t the current increases, according to the power law I ∼ (V − V t ) ζ with ζ = 1 in a one-dimensional (1D) and ranging between 5/3 and 2 in a two-dimensional (2D) array [1][2][3]. I denotes the current, V the voltage. Electronic coupling between individual particles is one of the fundamental parameters that governs charge transport in NP arrays. The coupling is influenced by inter-NP spacing and by stabilizer molecules capping the NPs. The inherent possibility of a switching between different molecular conformations represents one

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An in-situ infrared spectroscopic study of the adsorption of citrate on Au(111) electrodes

Cited by 76 publications

References 26 publications

Voltammetric and in situ FTIRS study on CN− and Au(CN)−x complexes at the polycrystalline gold surface in citrate medium

Voltammetric and in situ FTIRS study on CN− and Au(CN)−x complexes at the polycrystalline gold surface in citrate medium

Conductance Fluctuations in Chains of Particles Arising from Conformational Changes of Stabilizer Molecules

Charge Transport in Chain of Nanoparticles

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