In Situ Fourier Transform Infrared Spectroscopic Study of Bisulfate and Sulfate Adsorption on Gold, With and Without the Underpotential Deposition of Copper
IBM ALMADEN RESEARCH CENTER SAN JOSE CA
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In situ surface infrared IR spectroelectrochemistry is used to investigate the adsorption of sulfate SO42- and bisulfate HSO4- ions on polycrystalline gold surfaces in sodium sulfate and sulfuric acid, and also during copper underpotential deposition in sulfuric acid medium. In sodium sulfate solution, IR peaks due to surface sulfate and bisulfate are observed at potentials within the double-layer region on gold, and the ratio of IR peak intensities for sulfate to bisulfate increases as the applied potential is made more negative. In sulfuric acid, surface IR spectra indicate that adsorbed sulfate is favored at more positive potentials, while adsorbed bisulfate is prevalent at more negative voltages also, a potential-dependent reorientation of water is observed in the spectra. IR spectroelectrochemical data from a sulfuric acid system containing copper sulfate indicate that adsorbed sulfate is present on gold at more positive potentials, and its coverage increases when underpotentially deposited UPD copper is present on the gold substrate surface.
- Inorganic Chemistry
- Physical Chemistry
- Electricity and Magnetism
- Atomic and Molecular Physics and Spectroscopy