Details

Autor(en) / Beteiligte

• Manuputty, Manoel Y
• Dreyer, Jochen A H
• Yuan Sheng
• Bringley, Eric J
• Botero, Maria L
• Akroyd, Jethro
• Kraft, Markus

Titel

Polymorphism of nanocrystalline TiO2 prepared in a stagnation flame: formation of the TiO2-II phase

Ist Teil von

• Chemical science (Cambridge), 2019-02, Vol.10 (5), p.1342-1350

Ort / Verlag

Cambridge: Royal Society of Chemistry

Erscheinungsjahr

2019

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• A metastable “high-pressure” phase known as α-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.