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題名: Structure and Comparison of Platinum(111) and Platinum(100) Surfaces as a Function of Electrode Potential in Aqueous Sulfide Solutions
作者: Nikola Batina;James W. McCargar;Ghaleb N. Salaita;Lu, Frank;Laarni Laguren-Davidson;Lin, Chiu-Hsun;Arthur T. Hubbard
貢獻者: 化學系
日期: 1989-01
上傳時間: 2013-06-05T09:35:41Z
出版者: American Chemical Society
摘要: Studies are reported in which surface layers formed by immersion of well-defined Pt(ll1) and Pt(100) electrode surfaces into aqueous NazS solutions were characterized with regard to structure, composition, and reactivity by means of low-energy electron diffraction (LEED), Auger electron spectroscopy, electron energy-loss spectroscopy (EELS), linear scan voltammetry, and coulometry. Voltammetry reveals that only oxidative desorption of S occurs on the Pt surfaces; no S reductive desorption is observed over the useful potential range. Combined surface analysis data (Auger), vibrational spectra (EELS), and structural data (LEED) permit identification of adsorbed layer composition and structure on the Pt(ll1) and Pt(100) surfaces as a function of potential. At potentials between -0.6 and 0.0 V (vs Ag/AgCI), LEED reveals that
stable ordered adsorbed sulfur layers are formed on both surfaces: Pt(lll)(d3Xd3)R3O0-S and Pt- (100)(d2Xd2)R45�-S. The best clarity of the LEED patterns is found at pH 9. Potentials more positive than 0.0 V give rise to increasingly diffuse intensity related to oxidative desorption of S. Voltammograms for oxidative desorption of S from both surfaces are markedly different, indicating different mechanisms
of S oxidation at the two surfaces: at pH 9, four voltammetric peaks are present for S at the Pt(ll1) surface, compared with only one peak for the Pt(100) surface. Coulometric data reveal that approximately six electrons are transferred in oxidation of adsorbed S at both surfaces at pH less than 10. Voltammetric behavior of the sulfur layer is sharply dependent upon pH.
關聯: Langmuir, 5(1): 123-128
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