Electrocatalytic materials and techniques for the anodic oxidation of various organic compounds

摘要

The research presented within this thesis is devoted to the development of electrocatalytic materials and methods employed to catalyze oxygen-transfer reactions in aqueous media. The use of rotated disk electrodes for the generation of Koutecky-Levich plots was evaluated for several mechanisms to identify the efficacy of estimating the number of electrons (n ) and the heterogeneous rate constant (kh) from such plots. Two mathematical models for oxygen-transfer reactions were derived for no adsorption and weak adsorption of a model reactant to the rotated disk electrode. Theoretical equations were compared to experimental data and show good agreement. Lead dioxide film anodes were doped with Fe(III) and Bi(V) and compared to the activity of undoped electrodes for the voltammetric response of toluene and m-xylene. Very slightly doped Fe(III)-PbO 2 films showed equal or greater heterogeneous rate constants than very highly doped Bi(V)-PbO2. A single-pass electrochemical cell was developed for the electrochemical incineration of dilute chromatographic eluent solutions. Manganese sulfate co-dissolved with the sample compounds was found to deposit onto the Pt substrate and catalyze the anodic oxidation of many compounds used for chromatographic separations. Ultraviolet light was used as a photocatalyst in the oxidation of selected organic compounds at the anodes Fe(III)-doped PbO2 and Fe(III)-doped MnO2. The ultraviolet light was found to catalyze the oxidation of both UV absorbing and non-UV absorbing molecules, indicating that the UV light activates the semi-conducting metal oxide film rather than the molecule present within the diffusion layer of the electrode. Finally, initial investigations using a Fe(III)/Mn(IV)-doped PbO2 film indicate that this film selectively oxidizes phenol and aniline to acetic acid in the presence of ultraviolet light.