Benzyl Alcohol and Titanium TetrachlorideA Versatile Reaction System for the Nonaqueous and Low-Temperature Preparation of Crystalline and Luminescent Titania Nanoparticles

The reaction between TiCl4 and benzyl alcohol is a simple and nonaqueous procedure for the synthesis of highly crystalline titania nanoparticles at temperatures as low as 40 °C. XRD measurements prove the exclusive presence of the anatase phase. The particle growth depends strongly on temperature so that with the appropriate thermal conditions the particle size can be selectively adjusted in the range of 4−8 nm. Fine-tuning of the particle size is possible by a proper choice of the relative amounts of benzyl alcohol and titanium tetrachloride. Lowering the titanium tetrachloride concentration leads to a considerable decrease of particle size. BET measurements show particularly high surface areas, up to 345 m2/g for the smallest particles and 115 m2/g for the calcined material. TEM investigations reveal that the nanoparticles are nearly uniform in size and shape. The as-synthesized particles display only minor agglomeration, whereas the calcined material consists of completely nonagglomerated particles, with diameters ranging from 13 to 20 nm. The smallest particles are soluble in a THF/trioctylphosphine mixture that luminesces (425 nm) upon UV irradiation.