SERS STUDY OF THE ADSORPTION OF GELATIN AT A COPPER ELECTRODE IN SULFURIC-ACID-SOLUTION

The adsorption of gelatin at a copper electrode in sulfuric acid solution has been investigated in situ by SERS spectroscopy. The adsorption of gelatin at the copper electrode is supported by the presence of shoulder bands at 260 and 326 cm(-1) in all SERS spectra for gelatin, which are assigned to Cu-N vibrational modes, indicative of molecular adsorption via the nitrogen-containing amino acids groups of the molecule. The adsorption of gelatin at the copper electrode is dependent on electrode potential and, furthermore, is accompanied by coadsorption of anion species. In electrolytes containing low chloride concentrations, halide coadsorption with gelatin occurs at less negative potentials, while sulfate is observed as the coadsorbed species at more negative potentials. In solutions of high chloride concentrations, the halide ion is present on the electrode surface over the entire potential range investigated. Additionally, it is apparent that chloride may enhance the adsorption of gelatin at the electrode surface owing to an interaction between the surface adsorbed chloride and the amine groups of the gelatin molecule.