Do alkanethiols adsorb onto the surfaces of Tl-Ba-Ca-Cu-O-based high-temperature superconductors? The critical role of H{sub 2}O content on the adsorption process
- Northwestern Univ., Evanston, IL (United States)
- Univ. of Texas, Austin, TX (United States)
The reactivity of Tl{sub 1.4}Ba{sub 2}CaCu{sub 2}O{sub 7.0}, a high-temperature superconductor (HTSC), toward a redox-active adsorbate molecule with thiol functionality has been investigated as a function of solvent type and H{sub 2}O content. Previously it had been reported that alkanethiols do not stably chemisorb onto the surface of Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8}Tl{sub 2}Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} phases, bringing into question the generality of alkanethiol adsorption onto cuprate-based HTSCs. Herein, we show that under rigorously dry conditions, 11-mercaptoundecanoylferrocene (1) adsorbs cleanly onto the surface of Tl{sub 1.4}Ba{sub 2}CaCu{sub 2}O{sub 7.0} to form moderately stable, redoxactive monolayer films. The redox activity of 1 was used to estimate adsorbate surface coverage, and it is shown that the addition of H{sub 2}O to the modifying solutions of 1 adversely affects the monolayer adsorption process. No redox activity associated with 1 could be detected for electrodes soaked in 0.1 M solutions of 1 with 5% H{sub 2}O in ethanol, which was attributed to the formation of a BaCO{sub 3} corrosion layer that prohibited the adsorption of 1 onto the HTSC surface. The importance of sample stoichiometry on the adsorption process also is discussed. 15 refs., 1 fig., 1 tab.
- OSTI ID:
- 263200
- Journal Information:
- Langmuir, Vol. 12, Issue 11; Other Information: PBD: 29 May 1996
- Country of Publication:
- United States
- Language:
- English
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