Abstract
Pure rutile and rutile-anatase composite TiO2 nanoparticles have been successfully synthesized via an ionic liq.-assisted method by hydrolysis of titanium tetrachloride in hydrochloric acid. It is found that the phase compn. (ratio of rutile to anatase) of the products increases with increasing the content of ionic liq. EmimBr (1-ethyl-3-methyl-imidazolium bromide), therefore, TiO2 nanoparticles with controlled phase compns. can be obtained in high yields. The structural and morphol. characterizations of the resulting samples are investigated by means of X-ray powder diffraction (XRD), TEM, high-resoln. TEM (HRTEM), and BET anal., and the results indicate that the diams. of the anatase nanoparticles are in the range of 4-6 nm and the well-defined rutile nanorods are about 3-6 nm in diam. 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 EmimBr 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.
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