关键词: 铂, 硫, 拉曼光谱

Abstract: The paper reports the first in situ surface enhanced Raman scattering (SERS) spectroelectrochemistry study of sulfur adsorption and electro-oxidation on highly roughened polycrystalline Pt surface in both acidic and basic supporting electrolytes. The SERS spectra were taken at a constant electrode potential after accumulative electro-oxidation CVs of the Pt electrode with pre-adsorbed sulfur species and at different electrode potentials that were varied stepwise of the Pt electrode immersed in sulfur-containing electrolytes without pre-adsorbed sulfur species. In both cases,a dominant vibrational band at 299 cm -1 in acidic electrolyte but at 310 cm-1 in basic electrolyte was observed,which was assigned to the Pt—S stretching vibration. The Pt—S bond appeared quite strong as evidenced by the total blockage of the Pt surface for hydrogen adsorption and the need of multiple electro-oxidation CVs to completely remove the adsorbed sulfur. Additionally,a small amount of poly sulfur species (S8 or other types) as represented by a minor peak at 470 cm-1 was also observed in the acidic but not in the basic electrolyte. These poly sulfur species only bound to the Pt surface weakly and could be removed easily. This work yielded important information on sulfur adsorption and electro-oxidation on roughened,polycrystalline platinum surfaces and demonstrated the applicability and usefulness of the in situ SERS spectroelechemistry in investigating the chemistry of sulfur adsorption/poisoning on platinum surfaces.

Key words: platinum, sulfur, Raman spectroscopy