Preparation and photocatalytic activity of TiO 2 powders from titanium citrate complex using two-step hydrothermal treatments

Abstract

White, almost carbon-free TiO 2 powders were prepared from a titanium citrate complex ((NH 4) 4[Ti 2(C 6H 4O 7) 2(O 2) 2]·4H 2O) using a two-step hydrothermal treatment. The product yield, carbon contamination, and crystalline phase of TiO 2 depended on both the temperature and pH value for each treatment. Titanium was precipitated as a solid phase (H 2Ti 2O 5·H 2O) using the first hydrothermal treatment in the basic condition (pH = 12) at temperatures less than 150 °C. Then white rutile or anatase powder was crystallized using the second hydrothermal treatment at 200 °C. By changing the pH condition of the second hydrothermal treatment, rutile and anatase were synthesized selectively. The photocatalytic decomposition activity of obtained rutile powder for gaseous 2-propanol under visible light was increased by Cu-grafting.