| Abstract
| - Nanosized titania having the rutile crystalline structure was synthesized at room temperature using amicroemulsion-mediated system. The formed rutile particles had a diameter of 3 nm, which corresponds wellwith the droplet size of the water-in-oil microemulsion used for their preparation. The crystallinity wasmonitored by both X-ray diffraction (XRD) and electron diffraction, together with dark-field electronmicroscopy (TEM) and high-resolution TEM. The rutile had a high specific surface area (∼300 m2/g) accordingto N2 adsorption and the BET equation. To our knowledge, this is the highest specific surface area everreported for rutile. The rutile crystals aligned in a specific crystallographic direction forming elongatedaggregates 200−1000 nm in size, as observed by TEM and high-resolution TEM. The titania formation wasfollowed in situ using dynamic light scattering and UV−vis spectroscopy, and together with TEM and XRDperformed on samples collected throughout the duration of the titania synthesis, the results gave support fora formation scheme involving the initial formation of amorphous titania followed by crystallization of rutile.The photocatalytic performance of the formed material was evaluated by in situ Fourier transform infraredspectroscopy and compared to that of a rutile sample having a lower specific surface area (∼40 m2/g). TheTEM and formate adsorption experiments revealed that the high-surface-area rutile had a much higher fractionof (101) facets than the low-surface-area sample, which predominantly exposed (110) facets. In particular, anew bidentate formate (μ-formate) species bridge-bonded to the (101) facet could be identified withcharacteristic bands at 1547 and 1387 cm-1. The photodegradation rate of this species was found to be similarto the μ-formate species on the (110) facet. However, the overall formate degradation rate was larger on thehigh-surface-area rutile sample because of a high concentration of the more readily photodegradablemonodentate formate (η-formate) on that sample.
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