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PHOTOCHEMICAL AND PHOTOELECTROCHEMICAL STUDIES OF ELECTRON TRANSFER REACTIONS AT MODIFIED METAL OXIDE SEMICONDUCTOR ELECTRODES
Abstract
Photochemical and photoelectrochemical investigations have been made of dye modified semiconductor electrodes. Two studies of the electron transfer reaction leading to dye sensitized photocurrent production have been made. In the first study, a system to perform flash photolysis and kinetic spectroscopy experiments on a species adsorbed at an electrode surface was developed by combining internal reflection spectroscopy with flash photolysis. Organic sensitizers were adsorbed to single crystal TiO$\sb2$ and polycrystalline SnO$\sb2$, and the photochemical behavior of the dye at the surface observed on the microsecond time scale. The photochemical behavior of the dye at the surface correlates well with separately recorded photoelectrochemical characteristics. Two transients, the cation radical and triplet dye, were observed on the surface, and evidence for participation of the triplet in photocurrent production has been presented. The second study developed two techniques for light initiated covalent attachment of an organic dye to a metal oxide surface. These techniques were tested on polycrystalline ZnO and single crystal ZnO and TiO$\sb2$ electrodes, and the attachment verified photoelectrochemically. One technique, which used an aryl azide linking agent, has stability for photocurrent production of up to one year. The other technique, which involves an ester linkage directly to the surface, is stable for 24 hours. These methods, by virtue of being light initiated, may be used to attach organic compounds in domains on an electrode surface; evidence of the successful attachment in patterns is presented. Light initiated deposition of platinum on the ZnO surface in domains was also demonstrated. In an additional study, a sub-bandgap light induced transient absorption was found in low and moderately doped TiO$\sb2$ and SrTiO$\sb3$ single crystals. This absorption was found to decrease with increasing donor density.
Subject Area
Chemistry
Recommended Citation
RYAN, MARGARET AMY, "PHOTOCHEMICAL AND PHOTOELECTROCHEMICAL STUDIES OF ELECTRON TRANSFER REACTIONS AT MODIFIED METAL OXIDE SEMICONDUCTOR ELECTRODES" (1987). Doctoral Dissertations Available from Proquest. AAI8727104.
https://scholarworks.umass.edu/dissertations/AAI8727104