Rational design of novel electroactive clay nanocomposites modified with ferrocenyl surfactants of varying chain lengths.

摘要

The potential for exploiting clays in the design of electroactive nanocomposites for both industrial and environmental applications is great. However, electron transfer reactions utilizing clay as tailorable templates and/or participants due to electrochemically active metal sites within the clay structure have either not been attempted or are poorly understood. Because clays are ubiquitous, have a large surface area, have the ability to exchange cations, come in a variety of sizes, shapes, layer charge, and elemental composition, and are low cost, this is an area which has been underutilized. With the current emphasis on everything “nano” due to their desirable properties above and beyond similar larger scale systems, the time for this type of research is ripe.; Rational design of electroactive clay nanocomposites with unique electrochemical properties for environmental and charge storage applications was the specific goal of this Ph.D. project. These nanocomposites were formed both as thin layer films on an electrode surface and as bulk suspensions. Electroactivity was imparted by a series of ferrocenyl surfactants, anchored to the anionic clay electrostatically via a cationic trimethylammonium head group. The objective of electronic communication in clay matrices proceeded in two arenas: (1) ferrocene to ferrocene electron transfer in thin layer clay-modified electrodes and (2) ferrocene to clay structural Fe(III) electron transfer in bulk suspensions. Optimization for electron transfer reactions was achieved by systematically varying four parameters: clay type, surfactant chain length, interlayer spacing between clay layers, and oxidation/reduction potential. It has been demonstrated that electron transfer can occur between closely spaced ferrocene moieties in the clay interlayer. Futhermore, electron transfer was shown to occur between ferrocene and clay structural Fe(III). The major contribution of this work is the development of models which can be invoked to predict the occurrence of electron transfer in clay matrices.