Effects of Electrode Potential on the Adsorption Behavior of TBPS on an Au Surface
| Autor: | Shueh Lin Yau, Yuh Lang Lee, Taro Uchida, Klaus Krug, Masatoshi Osawa, Yung Fang Liu |
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| Rok vydání: | 2017 |
| Předmět: |
Chemistry
General Chemical Engineering Analytical chemistry Infrared spectroscopy 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences law.invention Adsorption law Electrochemistry Molecule Crystallite Scanning tunneling microscope Cyclic voltammetry 0210 nano-technology Spectroscopy Electrode potential |
| Zdroj: | Electrochimica Acta. 235:242-250 |
| ISSN: | 0013-4686 |
| DOI: | 10.1016/j.electacta.2017.03.072 |
| Popis: | Cyclic voltammetry (CV) and in-situ Surface-Enhanced Infrared Absorption Spectroscopy (SEIRAS) are used to study the adsorption behavior of an electroplating additive, 3,3 thiobis-(1-propanesulfonic acid sodium salt) (TBPS), on a polycrystalline Au(111) surface. The effects of the applied potentials on the adsorption behavior of TBPS are investigated and compared to that obtained by in-situ scanning tunneling microscopy (STM) in a previous work. The results show that TBPS molecules can adsorb on the Au surface at 0.05 V (RHE) and approach an equilibrium state after ca. 200 sec. For the IR spectrum detected in the air, the most pronounced peaks of TBPS are symmetric S O (ss-SO) and asymmetric S O (as-SO) stretching modes. Upon adsorption on the Au surface, the ss-SO peak still keeps a sharp and intense shape, while the as-SO peaks appear as a broad peak with much lower intensity. Since the ss-SO vibration mode is parallel to the long molecular axis, these results imply that the TBPS molecules mainly adsorb with a lift-up conformation at 0.05 V. With the increase in electrode potential, the ss-SO peak intensities first increase slightly due to further adsorption of the TBPS, and then, decrease steadily, ascribing to a conformation change of adsorbed TBPS molecules from an upright to a lie-down orientation. On the contrary, the as-SO band intensity first stays constant, and then, increases with increasing potential, consistent with the inference of the conformation change. Accompanying the adsorption and conformation change in the TBPS molecules, the peak corresponding to the bending mode of the adsorbed water δ(HOH) reflects that water molecules move away from the surface when TBPS molecules are adsorbed at low potentials, but will become closer again as the molecular conformation shifts to a lie-down orientation. The adsorption behavior of TBPS with respect to the potential change is reversible. |
| Databáze: | OpenAIRE |
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