Using the triblock copolymer Pluronic F127 (EO₁₀₆PO₇₀EO₁₀₆) as the templating agent and Ti(OBuⁿ)₄ as the titanium source, mesostructured TiO₂ thin films were constructed through the sol–gel and evaporation-induced self-assembly method. The effect of the calcination temperature on the mesostructure and on the hydrophilicity of the obtained mesoporous TiO₂ thin films was investigated. Small-angle and wide-angle X-ray diffractions, transmission electron microscopy, N₂ adsorption–desorption, and contact angle measurements were used to characterize the as-synthesized TiO₂ thin films. It was shown that the synthesized mesoporous TiO₂ materials exhibited an excellent thermal stability and possessed pores with a diameter larger than 7 nm and a narrow pore-size distribution, and thick inorganic walls composed of nanocrystalline anatase. The calcination temperature affected the stability of the mesoporous structures. In the range of 450–600 °C, the mesoporous framework was stable and the pore size was from 7.3 to 7.8 nm. Above 600 °C, however, the structure collapsed partially. On the basis of the film structure, a four-coordinate channel mode was proposed and the collapse criterion for the mesoporous structure was established through thermodynamic calculation. The synthesized mesoporous TiO₂ thin films showed excellent hydrophilicity without light illumination; for example, the film obtained after being treated at 600 °C had a contact angle of about 22.5°, whereas the sample treated at 500 °C (the particle and pore sizes were 10.2 and 7.5 nm, respectively) showed the optimal photoinduced hydrophilicity, with the contact angle of about 9.5°.

Bimodal mesoporous titania powders with high photocatalytic activity were prepared by hydrolysis of titanium tetraisopropoxide in the presence of HNO₃ or NH₄OH under ultrasonic irradiation. The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), BET surface areas, and X-ray photoelectron spectroscopy (XPS). Photocatalytic activity was evaluated by the photocatalytic oxidation of acetone in air. The effects of catalysts added during hydrolysis on the microstructure and photocatalytic activity of the TiO₂ powders were investigated. The results showed that HNO₃ enhanced the growth of brookite, while NH₄OH not only retarded phase transformation of the TiO₂ powders from amorphous to anatase and anatase to rutile but also suppressed the growth of brookite. All TiO₂ powders calcined from 400 to 600 °C showed bimodal pore-size distributions in the mesoporous region: one was intraaggregated pores with maximum pore diameters of ca. 4–9 nm and the other interaggregated ones with maximum pore diameters of ca. 35–50 nm. At 700 °C, the pore-size distributions of all samples exhibited monomodal distribution of the interaggregated pores due to the collapse of the intraaggregated pores. The photocatalytic activity of the TiO₂ powders prepared by this method and calcined at 400 °C exceeded that of Degussa P-25 when the molar ratio of HNO₃ or NH₄OH to H₂O was less than 0.05.

An interfacial sol−gel synthesis of inorganic hollow microspheres in room-temperature ionic liquids is newly developed. When metal alkoxides such as titanium tetrabutoxide, Ti(OBu)₄, are dissolved in anhydrous toluene and injected into 1-buthyl-3-methylimidazolium hexafluorophosphate ([C₄mim]PF₆) under vigorous stirring, hollow titania microspheres are formed. The present technique is widely applicable to the reactive metal alkoxides such as Zr(OBu)₄, Hf(OBu)₄, Nb(OBu)₄, and InSn₃(OR)_x, giving a general route to the metal oxide microspheres. When gold nanoparicles and carboxylate-containing dyes such as fluorescein isothiocyanate (FITC) are dissolved in the toluene microdroplets, they are stably immobilized in the microsphere shells. Calcination of the titania gel microspheres gives anatase TiO₂ microspheres. The present method provides the first example of inorganic hollow microspheres formed in ionic liquids, and the ability to modify microspheres with metal nanoparticles or functional organic molecules would be widely applied to the design of smart organic/inorganic hybrid materials.

Exploiting advanced photocatalysts under visible light is of primary significance for the development of environmentally relevant photocatalytic decontamination processes. In this study, the ionic liquid (IL), 1-butyl-3-methylimidazolium tetrafluoroborate, was employed for the first time as both a structure-directing agent and a dopant for the synthesis of novel fluorinated B/C-codoped anatase TiO₂ nanocrystals (T_IL) through hydrothermal hydrolysis of tetrabutyl titanate. These T_IL nanocrystals feature uniform crystallite and pore sizes and are stable with respect to phase transitions, crystal ripening, and pore collapse upon calcination treatment. More significantly, these nanocrystals possess abundant localized states and strong visible-light absorption in a wide range of wavelengths. Because of synergic interactions between titania and codopants, the calcined T_IL samples exhibited high visible-light photocatalytic activity in the presence of oxidizing Rhodamine B (RhB). In particular, 300 °C-calcined T_IL was most photocatalytically active; its activity was much higher than that of TiO_1.98N_0.02 and reference samples (T_W) obtained under identical conditions in the absence of ionic liquid. Furthermore, the possible photocatalytic oxidation mechanism and the active species involved in the RhB degradation photocatalyzed by the T_IL samples were primarily investigated experimentally by using different scavengers. It was found that both holes and electrons, as well as their derived active species, such as^.OH, contributed to the RhB degradation occurring on the fluorinated B/C-codoped TiO₂ photocatalyst, in terms of both the photocatalytic reaction dynamics and the reaction pathway. The synthesis of the aforementioned novel photocatalyst and the identification of specific active species involved in the photodegradation of dyes could shed new light on the design and synthesis of semiconductor materials with enhanced photocatalytic activity towards organic pollutants.

The near-spherical AgCl micro-crystals were prepared by anionic liquids-assistedhydrothermal method. The influence ofionic liquids (C_xMimClx = 4, 8, 12, 16) on (001) facet growth of AgCl was studied systemically. The composition of the as-prepared samples was characterized byX-ray diffraction (XRD),thermogravimetric analysis (TGA) andFTIR spectra. The morphological structures were characterized byscanning electron microscopy (SEM) andatomic force microscopy (AFM). Based onexperimental data and the classical crystal growth theory, a plausible growth mechanism of the near-spherical AgCl was proposed. The plasmonic photocatalyst Ag@AgCl prepared from the near-spherical AgCl showed higher activity than that of cubic morphologies.

Mesostructured TiO₂nanocrystals have been prepared usingPluronic F127 as the structure-directing agent.Platinum nanoparticles at different contents (0.1–1.0 wt%) have been photochemically deposited onto the mesoporous TiO₂. TEM investigation of 0.2 wt% Pt/TiO₂ calcined at 450 °C reveals that the TiO₂ particles are quite uniform in size and shape with the particle sizes of TiO₂ and Pt being 10 and 3 nm, respectively. The photocatalytic activities of the Pt loaded TiO₂ have been assessed and compared with those of nonporous commercial Pt/TiO₂-P25 by determining the rates and the photonic efficiencies of molecular hydrogen production from aqueous methanol solutions. The results show that the amount of hydrogen evolved on Pt/TiO₂-450 at low Pt loading (0.2 wt%) is three times higher than that evolved on Pt/TiO₂-P25 and twelve times higher than that evolved on Pt/TiO₂-350. Despite the BET surface area of the TiO₂-450 photocatalyst being 3.5 times higher than that of TiO₂-P25, a 60% smaller amount of the Pt co-catalyst is required to obtain the optimum photocatalytic hydrogen production activity. The reduced Pt loading on the mesoporous TiO₂ will be important both from a commercial and an ecological point of view.