A novel hydrolytic reaction to morphology-controlled TiO2 micro/nanostructures for enhanced photocatalytic performances

Abstract

Different TiO₂ micro/nanostructures have been hydrothermally prepared through controlling the hydrolysis and nucleation rate of Ti⁴⁺ ions by urea and H₂O₂ in a (NH₄)₂TiF₆ aqueous solution. Anatase TiO₂ nanorods with diameters of 10–30 nm and lengths up to 300–500 nm were evolved from the intermediate monoclinic H₂Ti₅O₁₁·3H₂O in the presence of H₂O₂ and urea, whereas TiO₂ core–shell nanospheres with diameters of 300–500 nm were obtained with the sole assistance of urea via the Ostwald ripening effect and TiO₂ microspheres with diameters of about 1–2 μm were formed in the presence of only H₂O₂. Photocatalytic degradation of Rhodamine B (RhB) has been used to evaluate their activities. The results indicate that the anatase TiO₂ nanorods have superior photocatalytic efficiency to the core–shell nanospheres and microspheres counterparts owing to their larger specific surface area and higher yield of ˙OH radicals. This work not only offers a simple and promising route to the controllable synthesis of various TiO₂ architectures, but also provides new insight for improving the photocatalytic performance of TiO₂ through morphological engineering, which will have potential applications in environmental remediation.