The chemisorption and anodic oxidation of hydroquinone (H2Q) and
benzoquinone (BQ) at palladium electrode surfaces was studied by a combination of
electrochemistry (EC), Auger electron spectroscopy (AES), high-resolution electron-
energy loss spectroscopy (HREELS) and electrochemical-scanning tunneling
microscopy (EC-STM) on a smooth polycrystalline and well-defined (single-crystalline)
Pd(100) electrode surface. The results point to the following more critical conclusions:
(i) Chemisorption of H2Q from dilute (less than or equal to 0.1 mM) aqueous solutions forms surface-
coordinated BQ oriented parallel albeit with a slight tilt. (ii) At high concentrations (greater than or equal to 1mM), chemisorption yields an edge-vertical oriented diphenolic species. (iii) The extent of anodic oxidation of the chemisorbed organic strongly depends upon its initial
orientation; only the flat-adsorbed species are oxidized completely to carbon dioxide.
(iv) The rate of anodic oxidation is likewise dependent upon the initial adsorbate
orientation; the rate for vertically-oriented species is more than twice that of flat-
adsorbed species. (v) The chemisorbed species are not oxidized (to the same extent)
simultaneously; instead, oxidation occurs one molecule at a time. That is, molecules that
survive the anodic oxidation and remain on the surface retain their original identities.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/3171 |
| Date | 12 April 2006 |
| Creators | Chen, Xiaole |
| Contributors | Soriaga, M. P. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 12912578 bytes, electronic, application/pdf, born digital |
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