Photoluminescence Characteristics of TiO₂ and Their Relationship to the Photoassisted Reaction of Water/Methanol Mixture

Abstract

This work investigated the photoluminescence characteristics of TiO2 and discussed the relationship between the photoluminescence features of TiO2 and the photoassisted reaction of water/methanol mixture. It is found that anatase TiO2 displays a visible luminescence band centered at about 505 nm and rutile TiO2 mainly shows a near-infrared luminescence band centered at about 835 nm, which are respectively ascribed to the oxygen vacancies in anatase TiO2 and the intrinsic defects in rutile TiO2. The visible luminescence band is easily quenched by the Pt deposited on the surface of TiO2, while the near-infrared luminescence band is hardly influenced by the deposited Pt. It is suggested that the excited electrons trapped in the oxygen vacancies of anatase are facilely transferred to Pt to contribute to the photoassisted reaction, but the electrons trapped in the intrinsic defects of rutile are not.

Photocatalytic oxidation of gaseous ammonia over fluorinated TiO2 with exposed (001) facets

“…Photoluminescence (PL) spectra of catalysts were next measured to investigate the efficiency of charge carrier trapping, migration, and transfer and the separation of photogenerated electron-hole pairs [47]. It was reported that a weaker PL emission signal is commonly indicative of higher photocatalytic activity [48,49].…”

Hydrogen Production by Photoreforming of Renewable Substrates

“…The valence bands of both phases have similar energy and thus contribute to the photooxidation of methanol in the same way. Furthermore, the anatase structure is usually more defective than the rutile one, but oxygen defects are alternatively believed as efficient electron traps, enhancing charge separation [45], or undesired recombination sites [46].…”

Fabrication and photoluminiscent properties of titanium oxide nanotube arrays

“…Anatase and rutile are the two main crystalline structures of TiO 2 , with band gap energies at 3.2 and 3.0 eV, respectively. 1 The photocatalytic activity of TiO 2 depends on its surface to volume ratio and crystal structure, and several studies have been performed in order to investigate these issues. 2,3 In particular, one dimensional TiO 2 such as nanotubes is more attractive because of its large specific surface area, which has more reactive sites to absorb and oxidize pollutants such as benzene, phenol, and p-chlorophenol.…”