IR and Raman spectroelectrochemical studies of corrosion films on tin

Abstract

Laser Raman spectroscopy and infrared reflection absorption spectroscopy methods have been applied to identify the surface film species generated on tin after dipping in 0.10 M NaOH, 0.15 M NaCl and pH 4.3 phosphate buffer solutions and exposing in air. From the spectroscopic data, both tin(II) and tin(IV) oxides were detected on the film formed in 0.10 M NaOH. On the film generated in 0.15 M NaCl and in pH 4.3 phosphate buffer solution, both oxide and hydroxide of tin(II) were identified. Surface-enhanced Raman spectroscopic spectrum collected in air right after the electrochemical deposition of silver showed the presence of tin (IV) hydroxide. As the air exposure time increased, the amount of tin(IV) hydroxide decreased and the relative quantities of tin(II) hydroxide, tin(II) and tin(IV) oxides increased. Electrochemical behaviors of tin in different aqueous solutions were also studied. Coupling the electrochemical technique and surface-enhanced Raman scattering, we have carried out the in situ identification of the corrosion films generated at different potentials in the aqueous solutions. The spectrum recorded in each of these solutions indicated the presence of tin (IV) hydroxide. From the variation of the spectral intensity with potential, we were able to verify the chemical process associated with some anodic and cathodic waves in the cyclic voltammograms.