Polymorphism of nanocrystalline TiO<sub>2</sub> prepared in a stagnation flame: formation of the TiO<sub>2</sub>-II phase.
MetadataShow full item record
Manuputty, M. Y., Dreyer, J., Sheng, Y., Bringley, E., Botero, M. L., Akroyd, J., & Kraft, M. (2019). Polymorphism of nanocrystalline TiO<sub>2</sub> prepared in a stagnation flame: formation of the TiO<sub>2</sub>-II phase.. Chemical science, 10 (5), 1342-1350. https://doi.org/10.1039/c8sc02969e
A metastable “high-pressure” phase known as a-PbO2-type TiO2 or TiO2-II is prepared via a single-step synthesis using a laminar premixed stagnation flame. Three other TiO2 polymorphs, namely anatase, rutile and TiO2-B phases, can also be obtained by tuning the oxygen/fuel ratio. TiO2-II is observed as a mixture with rutile under oxygen-lean flame conditions. To the best of our knowledge, this is the first time that this phase has been identified in flame-synthesised TiO2. The formation of TiO2-II in an atmospheric pressure flame cannot be explained thermodynamically and is hypothesised to be kinetically driven through the oxidation and solid-state transformation of a sub-oxide TiO2 x intermediate. In this scenario, rutile is nucleated from the metastable TiO2-II phase instead of directly from a molten/amorphous state. Mixtures containing three-phase heterojunctions of anatase, rutile, and TiO2-II nanoparticles as prepared here in slightly oxygen-lean flames might be important in photocatalysis due to enhanced electron–hole separation
National Research Foundation Singapore (via Cambridge Centre for Advanced Research and Education in Singapore (CARES)) (unknown)
External DOI: https://doi.org/10.1039/c8sc02969e
This record's URL: https://www.repository.cam.ac.uk/handle/1810/288522