A SERS STUDY ON ADSORPTION OF DIBENZYL DISULFIDE, SULFIDE, AND SULFOXIDE ON AN IRON-DEPOSITED SILVER ELECTRODE IN A HYDROCHLORIC-ACID SOLUTION

Adsorption modes of dibenzyl disulfide, sulfide, and sulfoxide on bare and iron-coated silver in 0.5M HCl were studied by surface-enhanced Raman scattering (SERS) spectroscopy. SERS spectra of these compounds were measured using a SERS-active silver electrode uncovered or covered with an electrodeposited iron layer SERS spectra of dibenzyl disulfide showed cleavage of a S-S bond and adsorption of phenylmethanethiolate ion on the silver and iron-deposited silver surface. Dibenzyl sulfide, which was chemisorbed on the metal surface by the formation of a coordinate bond, was not an effective inhibitor for iron corrosion in the acid solution. SERS spectra of dibenzyl sulfoxide on the metal surfaces in 0.5M HCl exhibited cleavage of a S-O bond to form dibenzyl sulfide through cathodic reduction and strong chemisorption of the sulfide thus formed on the surfaces, resulting in a high inhibition efficiency for iron corrosion. X-ray photoelectron spectra for the iron surface inhibited with the sulfoxide suggested the formation of a multimolecular layer of the sulfide-containing ferrous oxide and chloride on the surface.