Solvothermal Synthesis of Visible Light Responsible Titania

Abstract

Nitrogen-doped titania nanocrystals were prepared by “Homogeneous Precipitation-Solvothermal Process” in TiCl₃-hexamethylenetetramine (C₆H₁₂N₄) mixed solution. The phase composition, crystallinity, microstructure and specific surface area of titania greatly changed depending on pH and temperature. The titania powders prepared in TiCl₃-hexamethylenetetramine solutions at pH 1-6 and 190°C for 2 h consisted of single phase of brookite and that prepared at pH 9 was single phase of rutile. All titania powders prepared in the present study were yellow and showed excellent visible light absorption property and photocatalytic ability for nitrogen monoxide destruction under irradiation of the visible light (λ>510 nm). The photocatalytic activity of brookite prepared at pH 1-6 was superior to that of rutile prepared at pH 9. The photocatalytic activity under irradiation of visible light (λ>510 nm) slightly decreased with increasing calcination temperature up to 700°C and then greatly decreased at 800°C.