Water-Dichloromethane Interface Controlled Synthesis of Hierarchical Rutile TiO2 Superstructures and Their Photocatalytic Properties

A water-dichloromethane interface is used for synthesis and assembly of rutile TiO2 nanorods. By hydrothermal treatment of a dichloromethane solution of TiCl4 at the interface of water-dichloromethane, turning to no surfactant or template, hierarchical rutile TiO2 superstructures are developed. By tuning the molar ratio of reactants r(w) (H2O/TiCl4), the size and shape of the samples significantly change. At a low value of r(w), highly extended, robust, porous, and thick titania film with ordered rutile nanorod bundles are deposited at the interface. At a high value of r(w), powders consisting of hierarchical rutile nanorod spheres together with disordered nanorods are obtained. A rational formation mechanism is proposed on the basis of a range of experiments. The main factors influencing the morphologies of the samples may be attributed to the acidity of the reaction system and the adsorption ability of the precursor nanoparticles to the water-dichloromethane interface. The as-obtained rutile TiO2 hierarchical superstructures show higher photocatalytic property to decompose methylene blue (MB) dye compared with that of commercial P25, which can be ascribed to the contribution of high surface area and high crystallinity. Other applications, such as solar energy conversion, environmental remediation, and advanced optical/electric nanodevices may also benefit from the unique properties of the hierarchically rutile TiO2 superstructures.