Showing papers by "Prashant V. Kamat published in 1985"
TL;DR: In this article, it has been demonstrated that with the aid of the laser flash photolysis, one can carry out both the oxidation of SCN/sup -/ and the reduction of oxazine dye on the semiconductor particles simultaneously.
Abstract: Association of SCN/sup -/ with TiO/sub 2/ colloids in acetonitrile resulted in the appearance of an absorption band with a maximum around 285 nm. The apparent association constant as measured by a Benesi-Hildebrand plot was 350 M/sup -1/. Generation of (SCN)/sub 2//sup -/. was observed within the pulse duration (<8 ns) when the thiocyanate complex of TiO/sub 2/ in acetonitrile to 337-nm laser pulse excitation. The quantum yield for the production of (SCN/sub 2//sup -/. was determined to be 0.04. With the aid of the laser flash photolysis, it has been demonstrated that one can carry out both the oxidation of SCN/sup -/ and the reduction of oxazine dye on the semiconductor particles simultaneously. Effective capture of the holes and electrons enhanced the efficiency of the photoelectrochemical oxidation and reduction processes at these microelectrodes. 22 references, 6 figures, 1 table.
65 citations
TL;DR: In this article, a photogalvanic power conversion efficiency of 0.002% was achieved with thionine and colloidal TiO2 upon bandgap excitation.
Abstract: Thiazine and oxazine dyes have been photoelectrochemically reduced in colloidal TiO2 suspensions with bandgap excitation. The one-electron reduction of the dye, which resulted in the production of the semireduced radical ion, with quantum yield up to 0.1, further disproportionated to yield a stable leuco dye. The efficiency of the interfacial electron-transfer process is found to be dependent on the standard reduction potential of the dye. The feasibility of employing a colloidal semiconductor system in the operation of a photogalvanic cell is demonstrated. A photogalvanic power conversion efficiency of 0.002% was achieved with thionine and colloidal TiO2 upon bandgap excitation. The use of TiO2 colloid as a carrier for the deposition of a photoactive or an electroactive species on the electrode surface is also discussed.
48 citations
TL;DR: In this article, the effect of photoelectrochemical reduction of thionine to semithionine was investigated by means of steady photolysis and nanosecond laser flash photosynthesis.
39 citations
TL;DR: In this paper, the mechanism of photodegradation of poly(vinylpyrene) was elucidated by using ESR techniques and the lifetime of the excimer emission was approx.110 ns.
Abstract: Polymerization of 1-vinylpyrene in acetonitrile was achieved electrochemically at a conducting SnO/sub 2/ electrode by application of anodic potentials and photoelectrochemically at a n-GaAs semiconductor electrode under visible light irradiation. Both polymers exhibited characteristic excimer emission ..lambda../sub max approx. 480 nm) in both films and THF solutions similar to poly(vinylpyrene) synthesized by using Ziegler-Natta catalyst. The lifetime of the excimer emission was approx.110 ns. The mechanism of photodegradation of poly(vinylpyrene) was elucidated by using ESR techniques. 22 references, 7 figures, 1 table.
20 citations