Polycrystalline gold

Fig. 4.9 Schematic illustration of the electrosynthesis procedure using a sulfur-modified gold electrode and alternating exposure to indium- and sulfide ion containing aqueous baths, (a) A polycrystalline gold surface is first modified with a sulfur layer, (b) Indium is plated onto this layer forming indium sulfide, (c) Indium continues to deposit atop the indium sulfide layer, (d) Transfer back to a sulfide ion containing bath results in the suMdization of the residual indium sites. (Reprinted from [95], Copyright 2009, with permission from Elsevier)...

Yagi I, Lantz JM, Nakabayashi S, Corn RM, Uosaki K (1996) In situ optical second harmonic generation studies of electrochemical deposition of tellurium on polycrystalline gold electrodes. J Electroanal Chem 401 95-10... 

Ham S, Choi B, Paeng KJ, Myung N, Rajeshwar K (2007) Photoinduced cathodic deposition of CdTe nanoparticles on polycrystalline gold substrate. Electrochem Commun 9 1293-1297... 

Arai et al. (1997) used EQCM to study iodide absorption on polycrystalline gold in IM NaC104 containing different concentrations of Nal. Eigure 27.21 shows dynamic frequency change-potential A/-i curves for 0.1M NaC104 containing different concentrations of Nal. The frequency at potentials more positive than -0.8 V was less than that found without Nal. The frequency increased with... 

Fig. 16. XPS Au4/ and Oh levels for a polycrystalline gold electrode emersed from 0.1 molL HC10+ at different potentials. Shaded Au4/spectra represent the contribution of clean Au. The Ols spectra were recorded with twenty-fold sensitivity at 90° (15° for shaded Ols spectrum).

C.A. Widrig, C. Chung, and M.D. Porter, The electrochemical desorption of n-alkanethiol monolayers from polycrystalline gold and silver electrodes. J. Electroanal. Chem. 310, 335-359 (1991). 

CdSe CdSe was deposited on different substrates. The two-step method of the electrosynthesis of CdSe films, based on the initial chemical modification of polycrystalline gold surface with selenium overlayer was described [157]. In the second step, this overlayer was cathodically stripped as a Se in a Se(IV)-free electrolyte medium that was dosed with the requisite amounts of Cd(II) ions. 

The nucleation and growth mechanism of CdTe thin films at polycrystalline gold surface [203] and on the rough face side of a Si(lOO) were studied as a function of different potential steps. Schematic representation of CdTe formation is shown in [204]. 

The process of Pb deposition depends on the presence of adsorbed species. On polycrystalline gold, in HCIO4 acid solutions, a combined quartz crystal microbalance and probe beam deflection methods have pointed to three stages of the process - (1) water molecules release from gold surface, (2) metal UPD associated with adsorbed OH ions replacement, followed by (3) water formation [274]. In the presence of adsorbed anions or organic... 

Frumkin isotherm of Pb adsorption has been used to explain the shape of voltammetric peaks on polycrystalline electrodes and on the polycrystalline gold surface [279]. 

A chapter on the electrochemistry of gold was published in the 4th volume of Encyclopedia of Electrochemistry of the Elements in 1975. At that time, mostly polycrystalline gold (pc-Au) electrodes were used, although already in the early sixties, the studies involving single-crystal electrodes had also been published. It appears from a review of the recent literature that polycrystalline gold electrodes are still in use however, the following trends are emphasized the most ... 

Hoogvliet et al. [9] have proposed a pulsed-potential pretreatment procedure, which allows one to decrease, in a reproducible manner, surface roughness of mechanically polished polycrystalline gold electrodes by a factor of 2. 

Some attention has also been paid to the simultaneous adsorption of sulfate anions and organic compounds. Futamata [44] has detected coadsorption of water molecules and sulfate species with uracil on polycrystalline gold electrode, applying attenuated total reflection-infrared spectroscopy. The adsorbed sulfate species appeared either as S04 or HS04, depending on the pH of the electrolyte solution. Skoluda... 

Adsorption of Disulfides and Related Compounds Adsorption and further electrode reactions of different disulfides at gold electrodes depend on chemical properties of the adsorbates. It has been evidenced in some papers that at least for some disulfides, adsorption process involves the cleavage of the S—S bond. Adsorption of diphenyl disulfide on a polycrystalline gold electrode has been studied in detail by Borsari etal. [166]. They have proposed the mechanism of adsorption shown in Scheme 1 ... 

The redox behavior of a polycrystalline gold electrode in 0.1 M NH3 + 0.1 M NaCl04 solution has been investigated using electrochemical and spectrometric techniques [371]. Two gold compounds AuO and AuNH2 were distinguished at... 

Poskus and Agafonovas [483] have applied radioactive Tl-204 to study its UPD on a polycrystalline gold electrode in alkaline solutions. The potential dependence of the equilibrium surface concentration obtained from the radiometric method has been compared to that calculated from CV. Surface concentration of Tl decreased monotonically as the potential was changed from the more positive Nern-stian values. This dependence exhibited a minimum without reaching zero. At more positive potentials (with respect to the minimum), adsorption of T1+ induced by specifically adsorbed hydroxyl anions occurred. 

UPD current corresponding to voltammet-ric reduction of lead(II) was enhanced, compared to the current observed at a clean polycrystalline gold electrode ]490]. 

The immersion of a polycrystalline gold electrode into a chloroform/methanol (2 1, v/v) solution of the tetrachloride salt of 6 (Fig. 7.4) results in the adsorption of this electroactive thiol on the metal surface.270 Consistently, the cyclic voltammogram (Fig. 7.5a), recorded after an immersion time of 24 h and extensive rinsing of the electrode surface, shows the reversible reduction of the bipyridinium dications to the corresponding radical cations. In addition, zp increases linearly with v (Fig. 7.6a),... 

Figure 7.5 Cyclic voltammograms (0.1 M KC1, H20, V versus Ag/AgCl, 100 mV/s) recorded after the immersion of a polycrystalline gold working electrode in solutions of 6 for 24 h (a) and 7 for 1 h (b), 6 h (c), and 48 h (d) and extensive rinsing of the electrode surface.

Fig. 6.52. (a) Three-dimensional representation of current transients recorded for a polycrystalline gold electrode in a solution that contains 5 x 10 4 M pyridine over the potential region -0.75 V to +0.6 V (vs. saturated calomel electrode), (b) Three-dimensional representation of charge transients obtained by integration of the current transients shown in (a). In this drawing AcrM = AgM. (Reprinted from J. Stolverg, J. Richer, and J. Lipkowski and D. E. Irish, J. Electroanal. Chem. 207 213, copyright 1986, Fig. 4, with permission of Elsevier Science.)... 

Benzoic add was adsorbed on polycrystalline gold electrode at different potentials. It was found that the process is reversible in respect to the bulk concentration of benzoic add and electrode potential. The maximum of adsorption was found at 13 V vs. potential of hydrogen electrode in 0.1 M HC104. The dependence of the surface concentration of benzoic add adsorbed from 0.1 M hcio4 on the bulk concentration is given in Table P.2 ... 

D.N. Seidman and R.W. Balluffi. Sources of thermally generated vacancies in single crystal and polycrystalline gold. Phys. Rev., 139(6A) 1824-1840, 1965. 

R.W. Siegel, S.M. Chang, and R.W. Balluffi. Vacancy loss at grain-boundaries in quenched polycrystalline gold. Acta Metall. Mater., 28(3) 249-257, 1980. 

Coil nichrome wire tightly around a piece of polycrystalline gold wire (5 mm length, 1 mm diameter, > 99.99% gold) leaving one end of the nichrome extended out about 8 cm. 

Biebuyck HA, Bain CD, Whitesides GM. Comparison of organic monolayers on polycrystalline gold spontaneously assembled from solutions containing dialkyl disulfides or alkanethiols. Langmuir 1994, 10, 1825-1831. 

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