Adsorption of pyrazine at the polycrystalline gold-solution interface

Abstract

The thermodynamics of pyrazine adsorption onto a polycrystalline gold electrode was investigated quantitatively by employing chronocoulometry. The measurement of the charge density on the metal side of the metal-solution interface allowed the determination of the adsorption parameters. The film and surface pressures, the relative Gibbs surface excesses, the free energies of adsorption, and the electrosorption valency as functions of both electrode potential and surface charge density were calculated. The maximum Gibbs surface excess found for pyrazine is 5.8 X 1CT10 mol cm"2. The Gibbs free energy of adsorption determined at the potential and charge of maximum adsorption (0.25 V (SCE) and 17.5 /uC cm"2, respectively) is equal to -32.8 kJ mol"1. The adsorption of pyrazine on Au and Hg is compared, and the differences in the orientation of pyrazine molecules at the two interfaces are also discussed. In addition, the similarities between the adsorption of pyrazine and pyridine on a polycrystalline gold electrode are described.

An investigation of the adsorption of pyrazine and pyridine on nickel electrodes by in situ surface-enhanced Raman spectroscopy

“…3a). As can be seen from the spectrum, the three dominant bands at 1021, 1237 and 1591 cm À1 are attributed to the totally symmetric ring breathing (m 1 , A g ), the C-H in-plane deformation (m 9a , A g ) and the ring stretching (m 8a , A g ), respectively [57][58][59]87,88,91,92]. The spectrum also exhibits peaks at 703 cm À1 (m 4 , B 2g ) and 1527 cm À1 (m 8b , B 3g ).…”

“…As such, all of their properties have, deservedly, been extensively studied by electrochemistry and surface methods, including cyclic voltammetry, differential capacity techniques, chronocoulometry [57][58][59], X-ray photoelectron spectroscopy (XPS) and low-energy electron diffraction (LEED) [60,61]. The adsorption and orientation were observed to be dependent on the nature of the metallic surface.…”

Influence of Organic Adsorbates on the Under- and Overpotential Deposition of Copper on Gold Electrodes

“…However when the gold electrode is pretreated with 2,2'-BYP in 0.50 M H2S04 at = 1 mV s"1 between 0.0 and +1. 30 V, copper upd only shows a peak at about +0.49 V. The copper deposition charge is always larger than the stripping one and the difference increases with the cathodic potential limit (Fig. 8).…”

“…Pyrazine adsorption in neutral medium has been studied on polycrystalline [30] and single crystal [31,32] gold electrodes. Contrary to pyridine, the dipole moment for the isolated pyrazine molecule is equal to zero.…”

“…On the other hand the adsorption of numerous organic species on Au [28][29][30][31][32][33][34][35][36][37][38][39][40][41] and on platinum electrodes [18,19] has been investigated showing that they are able to hinder or even inhibit the deposition of copper and silver on platinum substrates [20,21].…”