Controllable hydrothermal synthesis of single-phase brookite TiO2 photocatalyst

Pure brookite TiO 2 with unique structure and property has demonstrated to be an interesting candidate in photocatalytic applications in recent years. In this study, single-phase brookite TiO 2 was controllable synthesized via hydrothermal method using titanium chloride (TiCl 4 ), sodium lactate and urea as starting materials. The structure and morphology of as-synthesized samples were characterized by various techniques, such as X-ray powder diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The band gap value of as-synthesized samples was calculated by ultraviolet–visible (UV–vis) spectroscopy. Experimental results showed that the co-existence of sodium lactate and urea contributed to the formation of single-phase brookite TiO 2 . The amounts of sodium lactate and urea had significant effects on the structure and morphology of as-synthesized samples. Sodium lactate acted as a key complexant, and the concentration of urea determined the crystalline structure of as-synthesized samples. Single-phase brookite TiO 2 was obtained when the amount of sodium lactate and urea was not less than 2.0 mL and 3.0 g, respectively. As the amount of sodium lactate or urea increases, the morphology of as-synthesized brookite TiO 2 changes from quasi-spherical structures to rod-like structures. This study might be useful for understanding how the pure structure of brookite TiO 2 is formed under given conditions and furtherly overcoming the difficulties of the preparation of pure brookite TiO 2 with high purity and large specific surface area, which limits its applications in the field of photocatalysis. Graphic abstract