Amorphous titania as a precursor to brookite-based materials obtained via hydrothermal treatment†

Abstract

Amorphous phases commonly accompany materials obtained through a number of methods, which often significantly change the functional properties of the materials. Thus, when present in photocatalysts, they decrease the photocatalytic performance of the materials significantly. To minimize the amorphous content in photocatalysts and increase their photocatalytic properties, hydrothermal post-treatment of amorphous photocatalysts is suggested. In this work, a series of brookite-based titania materials were obtained via the post-treatment of amorphous titania under hydrothermal conditions to determine how synthesis parameters affect the properties of the obtained TiO₂ materials. The samples were characterized via X-ray diffraction analysis, scanning and transmission electron microscopy, and low-temperature nitrogen adsorption analysis. Special attention was given to the amount of residual amorphous phases in the samples. Results indicated the possibility of selectively crystallizing titania materials with high brookite contents and enhanced photocatalytic properties from amorphous titania without significantly altering the form of the particles. This study presents the amorphous phase as a valuable precursor to obtain highly crystalline materials with vast control of phase composition.