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Degree

Doctor of Philosophy, Case Western Reserve University, Chemistry, 1990.

Abstract

Electrochemical interfaces were examined with Drude-Fresnel equations for the 3-phase system in order to obtain the dependence of infrared external reflectance spectra on the angle of incidence, the electrolyte layer thickness and the optical polarization state. Electrochemical effects such as ionic transports and pH changes in the spectroelectrochemical thin layer designed for external reflection were observed in in situ spectra. The IR peak intensity corresponding to the concentration change due to the net anions transported into the thin layer was proportional to the charge observed in the voltammetric measurements for Au or Pt anodic film formation in 0.1 M HClO₄, 0.1 M HNO₃, or mixed electrolyte solutions. The pH changes within the thin layer due to the charge passed between the working and counter electrode were also observed in the spectra for 0.1 M Na₂CO₃ and 0.1 M CH₃CO₂Na. Electrooxidation of glucose on Pt electrodes was studied by infrared spectroscopy in acid and alkaline electrolyte solutions to elucidate the reaction steps and to identify species strongly adsorbed on the electrode surface during the reaction. The strongly adsorbed species was the linearly adsorbed CO on Pt which is believed to poison the further oxidation of glucose on Pt in both 0.1 M H ClO₄ and 0.1 M NaOH. Gluconic acid and CO₂ were detected as the intermediate and the final product, respectively in the Pt oxide region. Transition metal macrocycles adsorbed on smooth surfaces and high area carbon were also investigated. The surface orientation of metalloporphyrin is believed to be strongly dependent on the method employed for the adsorption. This was evident from IR reflection-adsorption spectra for the adsorbed porphyrins on the basal plane of HOPG obtained from different adsorption methods. Voltammograms for metallomacrocycles adsorbed on such an electrode showed that some molecular restructuring occurs during the potential cycling. EXAFS studies of cobalt porphyrin adsorbed on high area carbon and its heat treatment product under inert atmosphere provided evidence for physisorption of this material on carbon and the pyrolysis product is containing reduced cobalt metal clusters. (Abstract shortened with permission of author.

Keywords

In situ infrared spectroscopic electrocatalytic systems

Advisor

Ernest B. Yeager

Pages

300p.

Document number: case1054670763
Permalink: http://rave.ohiolink.edu/etdc/view?acc_num=case1054670763

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