Ionic Liquid-Assisted Synthesis of Large-Scale TiO₂ Nanoparticles with Controllable Phase by Hydrolysis of TiCl₄

Abstract

Pure rutile and rutile-anatase composite TiO(2) nanoparticles have been successfully synthesized via an ionic liquid-assisted method by hydrolysis of titanium tetrachloride in hydrochloric acid. It is found that the phase composition (ratio of rutile to anatase) of the products increases with increasing the content of ionic liquid [Emim]Br (1-ethyl-3-methyl-imidazolium bromide), therefore, TiO(2) nanoparticles with controlled phase compositions can be obtained in high yields. The structural and morphological characterizations of the resulting samples are investigated by means of X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and Brunauer-Emmett-Teller (BET) analysis, and the results indicate that the diameters of the anatase nanoparticles are in the range of 4-6 nm and the well-defined rutile nanorods are about 3-6 nm in diameter and 20-60 nm in length. More importantly, we find that the [Emim](+) ions can serve as capping agents based on their strong interactions with the (110) facets of rutile, and the [Emim]Br favors the formation of the rutile structure with a rod-like shape due to the mutual pi-stacking interactions of imidazole rings. We believe that this method can be developed into a general way to synthesize other metal oxide nanoparticles on a large scale.

Oxide Nanomaterials: Synthetic Developments, Mechanistic Studies, and Technological Innovations

“…[205] The correlation between the type of ionic liquid and the resulting TiO 2 modification was investigated in detail for the hydrolysis of TiCl 4 in a HCl/IL system. [206] The rutile/anatase ratio is strongly influenced by the amount of the IL [Emim] [Br], and both modifications differ considerably with respect to their morphologies (anatase nanoparticles of 4-6 nm in size vs. rutile nanorods up to 60 nm in length and 3-6 nm in diameter). The formation of rutile nanorods can again be explained with a specific surface interaction on the (110) facet of rutile and a stacking of imidazole rings ( Figure 12) which cannot take place with the anatase structure.…”

Synthesis and development of titania with controlled structures

“…The distance between the aromatic rings is of 0.60.7 nm depending on the direction. 40) This space can be properly provided on the {111} facets where the distance of TiTi atoms of 0.546 nm-0.649 nm is the largest among low-index planes of rutile. As a result, {111} facets were partially grown together with {110} facets to form pyramidal shape crystals, resulting in formation of high-index surfaces.…”

Synthesis and Enhanced Photocatalytic Activity of Black Porous Zr-doped TiO2 Monoliths

“…The black porous Zrdoped TiO 2 monolith samples calcined at 500 C for 26 Thus, the photocatalytic activity under visible light is e±ciently improved. Particularly, Zr ions are most likely located at the surface of the nanocrystalline structure, facilitating separation of charge carriers more e±ciently, which prolongs the lifetime of carriers and inhibits the recombination of h þ /e À pairs.…”