Dynamics of Pyridine Adsorption on Gold(111) Terraces in Acid Solution from in-Situ Scanning Tunneling Microscopy under Potentiostatic Control
The adsorption of pyridine (Py) on Au(111) terraces produced from aqueous 0.1 M HClO<sub>4</sub> + 10-<sup>3</sup> M Py at 298 K was studied in the potential range 0.15 V < E < 0.55 V (vs SHE) by in-situ scanning tunneling microscopy. When E ≥ E<sub>pzc</sub>, the potential of zero charge of the sub...
| Autores: | ; ; ; |
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| Tipo de documento: | Artigo |
| Estado: | Published version |
| Data de publicação: | 1997 |
| País: | Argentina |
| Recursos: | UNLP |
| Repositório: | SEDICI (UNLP) |
| Idioma: | Inglês |
| OAI Identifier: | oai:sedici.unlp.edu.ar:10915/85927 |
| Acesso em linha: | http://sedici.unlp.edu.ar/handle/10915/85927 |
| Nível de acesso: | Acesso aberto |
| Palavra-chave: | Ciencias Exactas Química Piridinas Oro scanning tunneling microscopy potentiostatic Metales Electroquímica |
| Resumo: | The adsorption of pyridine (Py) on Au(111) terraces produced from aqueous 0.1 M HClO<sub>4</sub> + 10-<sup>3</sup> M Py at 298 K was studied in the potential range 0.15 V < E < 0.55 V (vs SHE) by in-situ scanning tunneling microscopy. When E ≥ E<sub>pzc</sub>, the potential of zero charge of the substrate, both ordered and disordered domains can be observed. Ordered domains correspond to vertically adsorbed Py molecules forming a (4 × 4) hexagonal lattice with the nearest neighbor distance d = 0.38 nm, and corrugation z = 0.04 nm. The ordered adsorbate structure disappears for E < E<sub>pzc</sub>, but it is recovered several minutes after stepping E backward to E > E<sub>pzc</sub>, as expected for a reversible potential-step-induced surface process. The surface concentration of adsorbed Py molecules resulting from the (4 × 4) lattice is close to 1 × 10-<sup>9</sup> mol/cm<sup>2</sup>, a figure exceeding the average integral surface concentration value obtained from electroadsorption measurements. Therefore, disordered domains would be related to a mobile diluted Py adsorbate coexisting with ordered Py adsorbate domains leading to a nonhomogeneous Py adsorbate layer at the positively charged Au(111) terraces. |
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