Synthesis and Characterization of Titanium Dioxide Phases in Mesostructured Silica Matrices with Photocatalytic Activity

Abstract

An imidazole type ionic liquid (IL), 1‐hexadecyl‐3‐methylimidazolium chloride (I16IL) was used as a template in the preparation of mesoporous silica with incorporated titanium dioxide. In this process, the IL is the structural template as well as the source of the Ti. The steps leading to the formation of the nanocrystalline metal oxide include: a) formation of metal‐containing IL (M‐IL); b) using the M‐IL as a template for the mesoporous silica; c) calcination of the sample to remove the organic moiety, while leaving the metal centers to form oxides on the porous framework. By varying the TiO2–SiO2 calcination temperature, the particle size and phase of TiO2 have been studied. These TiO2–SiO2 hybrid materials were characterized by using various physicochemical techniques, such as UV/Vis diffuse‐reflectance spectroscopy, Raman spectroscopy, X‐ray diffraction, N2 adsorption‐desorption isotherm measurement, Fourier transform infrared spectroscopy, and transmission electron microscopy. The resultant hybrid silica demonstrated effective photocatalytic activity for the oxidation of cyclohexene and styrene.

Versatility of heterogeneous photocatalysis: synthetic methodologies epitomizing the role of silica support in TiO2 based mixed oxides

“…This is owed to tunable solvent properties that can readily interact with various surfaces to facilitate the distribution of particles by in situ formation of metal oxide nanoparticles on the mesoporous supports. Gopala et al 119 demonstrated a facile method of introducing Ti centres into the mesoporous silica support by impregnation of an acidic solution of TiCl 4 mixed in N,N-dialkylimidazolium chloride type ILs such as 1-hexadecyl-3-methylimidazolium chloride. It forms a mesophase in aqueous solution with the TEOS precursor as well as interacts with the TiCl 4 to form an imidazole based chlorometalate complex, Ti-I 16 IL.…”

Photocatalytic decomposition of Rhodamine B on uranium-doped mesoporous titanium dioxide

“…The band gap energy of undoped TiO 2 was found to be 3.0 eV, which is in good agreement with the reported value for anatase TiO 2 (3.1-3.2 eV). 39,[48][49][50] Incorporation of U into the TiO 2 matrix leads to a narrower band gap, and the TiU3 sample has the lowest band gap energy (2.0 eV). These results show that a small amount of U-doping can signicantly modify the band gap structure of TiO 2.…”

Hexadecyl-Containing Organic Salts as Novel Organogelators for Ionic, Eutectic, and Molecular Liquids

“…It should be noted that [C 16 -mim]-based salts were previously used either as surfactants or as a part of the gel composites. − In addition, the cetyl-containing, CO 2 H-functionalized imidazolium salt [N-C 16 ,N′-CO 2 H-im]­Br was used to gel a binary (H 2 O/DMSO) mixture at 20 wt %, whereas [C 16 -mim]­Br, which was used as a control, failed to induce the gelation . Furthermore, betaine-ester imidazolium bromide, that is, [C 1 ,(CH 2 CO 2 )­C 16 -im]Br (at 21.9–49.3 wt % concentration), was used for gelation of wet CHCl 3 ; the MGC for [C 1 ,(CH 2 CO 2 )­C 16 -im]­PF 6 and [C 1 ,(CH 2 CO 2 )­C 16 -im]­BF 4 salts was above 50 wt % .…”