CONFIRMATION OF THIOUREA CHLORIDE ION COADSORPTION AT A COPPER ELECTRODE BY IN-SITU SERS SPECTROSCOPY/

The co-adsorption of chloride with thiourea and sulfate ions at a copp er electrode in sulfuric acid solution has been investigated in situ b y SERS spectroscopy. The presence of the halide species in solution an d subsequent adsorption at the copper electrode leads to enhancement o f the SERS spectra for the adsorption of thiourea and sulfate ions at the copper electrode. The in situ SERS spectra indicate that the adsor ption of chloride at the copper electrode is dependent upon electrode potential and solution chloride concentration. The co-adsorption of ch loride at the copper electrode in sulfuric acid electrolyte containing thiourea is particularly favoured at low potentials and is characteri sed by the presence of a distinct band at 300 cm(-1) which is assigned primarily to a Cu-Cl vibration. However, this band contains secondary contributions from Cu-S and Cu-O vibrations arising from the co-adsor ption of thiourea and sulfate species at the copper electrode respecti vely.