Do Alkanethiols Adsorb onto the Surfaces of Tl−Ba−Ca−Cu−O-Based High-Temperature Superconductors? The Critical Role of H₂O Content on the Adsorption Process

Abstract

The reactivity of Tl1.4Ba2CaCu2O7.0, a high-temperature superconductor (HTSC), toward a redox-active adsorbate molecule with thiol functionality has been investigated as a function of solvent type and H2O content. Previously it had been reported that alkanethiols do not stably chemisorb onto the surface of Tl2Ba2CaCu2O8/Tl2Ba2Ca2Cu3O10 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 Tl1.4Ba2CaCu2O7.0 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 H2O 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% H2O in ethanol, which was attributed to the formation of a BaCO3 corrosion layer that prohibited the adsorption of 1 onto the HTSC surface. The importance of sample stoichiometry on the adsorption process also is discussed.

Self‐Assembled Monolayers on Electrodes

“…76 Other substrates for thiol SAMs include nickel, 77,78 indium tin-oxide, 79 indium phosphide, 80 and a Tl-BaCu-O high-temperature superconductor. 81 …”

The chemical and adsorption effects of foreign molecules on the properties of high-temperature superconductors

“…Cyclic voltammetry was used to study the effect of small amounts of water on the adsorption of 11-mercaptoundecanoylferrocene (MUF) on the surface of the Tl 1.4 Ba 2 CaCu 2 O z ceramic. 233 The presence of 5% water in a 0.1 M solution of MUF in acetonitrile decreased considerably the degree of coverage of the ceramic's surface with MUF molecules. If ethanol was used as the solvent, adsorption virtually did not occur.…”

Properties of thiolate monolayers formed on different amalgam electrodes

“…Gold [1][2][3], silver [4][5][6], platinum [7,8], copper [6,[9][10][11][12] and mercury [13][14][15][16][17] are the usual materials for the SAM formation. But also some other materials have been applied as substrates for various SAMs: palladium [18][19][20][21], nickel [22,23], iron (mild steel) [24], aluminum [25], zinc [26], indium phosphide [27], indium tin oxide [28], gallium arsenide [29], Ti-Ba-Ca-Cu-O-based high temperature semiconductors [30] and glassy carbon [31,32]. The range of the SAMs applications is wide, spanning from biosensors and model phospholipid membranes up to anticorrosion protection of metals [33].…”