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 solut ion has been investigated in situ by SERS spectroscopy. The adsorption of gelatin at the copper electrode is supported by the presence of sh oulder bands at 260 and 326 cm(-1) in all SERS spectra for gelatin, wh ich are assigned to Cu-N vibrational modes, indicative of molecular ad sorption via the nitrogen-containing amino acids groups of the molecul e. The adsorption of gelatin at the copper electrode is dependent on e lectrode 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 i on 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 interac tion between the surface adsorbed chloride and the amine groups of the gelatin molecule.