Characterization of Titanium−Silicon Binary Oxide Catalysts Prepared by the Sol−Gel Method and Their Photocatalytic Reactivity for the Liquid-Phase Oxidation of 1-Octanol

Abstract

Titanium-silicon (Ti/Si) binary oxides having different Ti contents were prepared by the sol-gel method and used as photocatalysts. The photocatalytic reactivity of these catalysts was investigated as a function of the Ti content for the liquid-phase oxidation of 1-octanol to 1-octanal, and it was found to be dramatically enhanced in regions of lower Ti content. In situ photoluminescence, UV-vis reflectance, FT-IR, ESR, XAFS, XRD, and XPS spectroscopic investigations of these Ti/Si binary oxides indicated that the titanium oxide species are highly dispersed in the SiO 2 matrixes and exist in a tetrahedral coordination exhibiting a characteristic photoluminescence spectrum due to the radiative decay from the charge-transfer excited state of the tetrahedrally coordinated titanium oxide species. The good parallel relationship between the yield of the photoluminescence and the specific photocatalytic reactivity of the Ti/Si binary oxides as a function of the Ti content clearly indicates that the high photocatalytic reactivity of the Ti/Si binary oxides having a low Ti content is associated with the high reactivity of the charge-transfer excited state of the isolated titanium oxide species in tetrahedral coordination, [Ti 3+ -O -]*.

Preparation of TiO2-Coated Polyester Fiber Filter by Spray-Coating and Its Photocatalytic Degradation of Gaseous Formaldehyde

“…The bands at 1060 cm −1 and 1080 cm −1 can be assigned to the asymmetric stretching and bending mode of the Si-O-Si banding (Shafei et al, 1995;Mohamed et al, 2002). A band at 950 cm −1 can be assigned to the stretching of Si-O species of the Ti-O-Si linkage which is formed by the inclusion of Ti 4+ into the SiO 2 matrixes (Yamashita et al, 1998). Combining all the information provided, it implies that TiO 2 species were embedded into SiO 2 matrixes through the high pressure spray coating approach.…”

Photocatalytic Activity of TiO2-containing Al-Mesoporous Silica Thin Films

“…This fact shows that the TiO 2 thin films on the surface of Al-MSF are assumed to be highly and homogeneously dispersed and minimized up to nanoorder thickness. This hypsochromic shift of the end absorption of the band gap of the semiconductors are well-known as "quantum size effect", which has sometimes observed in cases of the TiO 2 supported on zeolites (15)(16)(17)(18). Moreover, TiO 2 modification of Al-MSF was confirmed by the stretching vibrations of Ti-O observed at 1087 cm -1 and Ti = O at 975 cm -1 , as shown in Fig.…”

コロイド状および担持ナノ粒子の設計─その合成，構造解析と触媒作用─

“…Figure 9A shows the Ti K-edge X-ray absorption near edge structure (XANES) spectra of the FePt@Ti several well-defined pre-edge peaks. These characteristic pre-edge peaks can be attributed to the transitions from the 1s core level of Ti to three different kinds of molecular orbitals (1t1g, 2t2g, and 3eg) of anatase TiO2 in a symmetric octahedral environment 68), 69) . On the other hand, the FePt@Ti _ SiO2 and Ti(O i Pr)4 were found to exhibit an intense single pre-edge peak due to the lack of an inversion center in the regular tetrahedron structure 68),69) .…”