A SERS investigation of the electrodeposition of Au in a phosphate solution

The spectroelectrochemical behaviour of cyanide and phosphate ions adsorbed on a An electrode during electrodeposition and corrosion in a KAu(CN)(2) phosphate bath was studied by in situ SERS (Stojace Enhanced Raman Spectroscopy) and cyclic voltammetry. SERS spectra exhibiting features corresponding to CN- and PO4- vibrations were recorded under potentiostatic control in an interval from - 1600 to + 1500 mV vs. Ag/AgCl. Surface CN- species are the dominating ones under both cathodic and anodic polarisations. As far as the phosphate vibrations are concerned, bands related to PO4- are visible in both cathodic and anodic conditions. A fluorescence background was evident in the potential range - 1300 divided by + 1300 mV At cathodic potentials phosphate ion adsorption on electrode surface prevails over cyanide for potentials more cathodic than - 1000 mV At - 700 mV a discontinuity is noticed in the Stark tuning of CN-, probably due to a change of Au(CN)(2)(-) adsorption mechanism. At anodic potentials bands due to cyanide oxidation could be observed. (c) 2006 Elsevier B.V. All rights reserved.