Tamihiko Kato, B. Loo, Masaharu Yokomaku
Sep 1, 1995
Citations
0
Influential Citations
3
Citations
Journal
Spectroscopy Letters
Abstract
Abstract The formation of colored formazans from the reduction of colorless tetrazolium salts was found to occur on the surfaces of photoexcited TiO2 and ZnO powders in ethanol solutions. The yields of the conversions of 2,3,5-triphenyltetrazolium chloride to 1,3,5-triphenylformazan and of 2,5-diphenyl-3-(l-naphthyl)tetrazolium chloride to 1,3-diphenyl-5-(l-naphthyl)formazan were 41.6% and 40.0%, respectively, after a 25-min UV irradiation in the TiO2 suspension, whereas they were 55.8% and 35.2%, respectively, after a 60-min UV irradiation in the ZnO suspension. These reactions proceeded via photoelectrochemical reduction by the electrons from the conduction bands of the semiconductors, but were quenched in the presence of oxygen or Ag+ ions.