title: Time-resolved chemiluminescence study of the TiO2 photocatalytic reaction and its induced active oxygen species.
abstract: The time-resolved chemiluminescence (CL) method has been applied to study the TiO(2) photocatalytic reaction on a micros-ms timescale. The experimental set-up for time-resolved CL was improved for confirmation of the unique luminol CL induced by the photocatalytic reaction. The third harmonic light (355 nm) from an Nd:YAG laser was used for the light source of the TiO(2) photocatalytic reaction. Luminol CL induced by this reaction was detected by a photomultiplier tube (PMT) and a preamplifier was used for amplifying the CL signal. Experimental conditions affecting the photocatalytically induced CL were discussed in detail. The involvement of active oxygen species such as .OH, O(2) (.-) and H(2)O(2) in the CL was examined by adding their scavengers. It is concluded that .OH was greatly involved in the CL on a micros-ms timescale, especially in time periods <100 micros after illumination of the pulse laser. On the other hand, CL generated by O(2) (.-) began to increase after 100 micros and became dominant after 2.5 ms. A small part of the CL might be generated by H(2)O(2) on the whole micros-ms timescale. A CL reaction mechanism related with .OH and dissolved oxygen was proposed to explain the photocatalytically induced luminol CL on a micros-ms timescale, especially in periods <100 micros.
authors.affiliation: Department of Materials Science and Engineering, Faculty of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan.
authors.forename: Lingyue
authors.initials: L
authors.lastname: Min
authors.forename: Xing-Zheng
authors.initials: XZ
authors.lastname: Wu
authors.forename: Shimada
authors.initials: S
authors.lastname: Tetsuya
authors.forename: Haruo
authors.initials: H
authors.lastname: Inoue
mesh_terms: D002384:Catalysis; D008163:Luminescent Measurements / Q000295:instrumentation / Q000379:methods; D008165:Luminol / Q000737:chemistry; D015394:Molecular Structure; D010777:Photochemistry; D017382:Reactive Oxygen Species / Q000032:analysis*; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*
chemical_list: D017382:Reactive Oxygen Species; C009495:titanium dioxide; D008165:Luminol; D014025:Titanium