An in situ SERS investigation of the chemical states of sulfur species adsorbed onto Pt from different sulfur sources

The paper reports in situ surface enhanced Raman scattering (SERS) spectroelectrochemistry study of sulfur adsorption and electro-oxidation on highly roughened polycrystalline Pt surface. It is intended to address a specific question: Does the final chemical state of the adsorbed sulfur species depend on the initial chemical state of the sulfur in deposition sources? Three different sulfur deposition sources were used: Na2S solution, electrochemically reductive SO2 solution, and S0 suspension. In all cases, the same dominant vibrational band at 300 cm−1 was observed on the freshly prepared S-adsorbed Pt electrode, indicating the same chemical state of the adsorbed sulfur which was recently assigned as the Pt–S2−. Possible spill-over sulfur adsorption from the deposited solid polymeric S 8 0 was observed. Overall, this work yielded important information on sulfur adsorption and electro-oxidation on roughened, polycrystalline platinum surfaces and demonstrated clearly the applicability and usefulness of the in situ SERS spectroelectrochemistry in investigating the chemistry of sulfur adsorption/poisoning on platinum surfaces.