Two-stage, non-hydrolytic synthesis for improved control of TiO2 nanorod formation

TiO2 anatase nanorods were grown via the non-hydrolytic elimination reaction between TiCl4 and Ti ((OPr)-Pr-i) (4) in the presence of oleic acid. The reaction was carried out in two stages in order to separate TiOx seed nucleation at lower temperatures from nanorod growth at higher temperatures. This separation made it possible to study the crystal growth mechanism in more detail, indicating that nanorod formation occurred through a combination of atom-by-atom addition and oriented attachment of the initial seeds. The two-stage reaction approach also enabled considerably improved control of titania nanorod formation in terms of product morphology, crystallinity and uniformity. The effects of a range of reaction parameters, including reaction duration, temperature, dilution and stoichiometry, were investigated.