UC Irvine

Chemically modified electrodes are useful for a wide variety of applications such as catalysis, sensing, and electronics. The attachment of molecular electrocatalysts onto electrode surfaces is of particular interest for the enhancement of heterogeneous redox catalysis. This dissertation describes a synthetically versatile approach for the immobilization of molecular species to conducting and semiconducting surfaces. Indium tin oxide (ITO) and silicon surfaces are covalently modified with aromatic molecules followed by attachment of aromatic-appended molecular species via π-¬π interactions.

Chapter 2 describes the immobilization of ferrocene onto ITO through covalent and non-covalent interactions and compares electron transfer kinetics between the two attachment methods. Electron transfer kinetics across the non-covalently modified interface demonstrate a ten-fold increase relative to the analogous covalent attachment strategy.

Chapter 3 outlines the attachment of a pyrene-bound anthraquinone derivative to pyrene-appended ITO. Comparison of the proton-coupled electron transfer properties of the surface-bound anthraquinone to that of a water soluble anthraquinone derivative demonstrates that the immobilized molecule retains its expected reactivity based on a similar homogeneous system.

Chapter 4 describes the attachment of a pyrene-appended molecular water oxidation catalyst to ITO via π-¬π interactions. Electrochemical analysis proves successful attachment of the catalyst to ITO. However, the modified electrode is unstable under electrocatalytic conditions due to loss of the catalyst from the electrode surface.

In Chapter 5, four aromatic molecules are covalently attached to nanoporous silicon electrodes followed by non-covalent attachment of a molecular proton reduction catalyst with aromatic ligands. Photoelectrochemical and impedance techniques are utilized to probe the light-assisted electrocatalytic proton reduction ability of the modified silicon electrodes.