Hydrothermal crystallisation of anatase and characterisation of photocatalytic properties

Hydrothermal processing has been used to prepare anatase powders from amorphous titania, for use as photocatalysts. There is a change in crystallisation mechanism from solid state to dissolution/precipitation at around 250degreesC, which has been shown to result in the removal of the brookite secondary product which normally occurs at lower temperatures. The use of a slightly basic solution has also been shown to eliminate brookite production. Photocatalysis experiments have shown that the hydrothermally produced powders have a high activity when compared to the commercial powder Degussa P25. The presence of the brookite phase in some samples reduces the activity.