Flame Synthesized Blue TiO with Tunable Oxygen Vacancies from Surface to Grain Boundary to Bulk.

Fabrication of nonstoichiometric metal oxides containing oxygen vacancies (OVs) has been an effective strategy to modulate their (photo)catalytic or (photo)electrochemical performances which are all affected by charge transfer at the interface and in the bulk. Considerable efforts are still needed to achieve tunability of OVs, as well as their quantitative characterization. Herein, a one-step flame synthesis method is reported for the first time for fast fabrication of blue TiO with controllable defect content and location.

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

A metastable "high-pressure" phase known as α-PbO-type TiO or TiO-II is prepared a single-step synthesis using a laminar premixed stagnation flame. Three other TiO polymorphs, namely anatase, rutile and TiO-B phases, can also be obtained by tuning the oxygen/fuel ratio. TiO-II is observed as a mixture with rutile under oxygen-lean flame conditions.