Effect of key parameters on the morphology transformation of three-dimensional TiO2 solid microspheres

Three-dimensional (3D) TiO2 solid microspheres with different morphologies have been synthesized on a large scale by a simple hydrothermal method using titanium tetrachloride (TiCl4) as the titanium source and ammonium fluoride (NH4F) as the etchant. X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM) studies show that the 3D solid microspheres, with an average diameter from hundreds of nanometers to several micrometers, are composed of numerous anatase TiO2 particles. In addition, the morphologies of the as-prepared 3D solid microspheres can be controlled by adjusting the dosage of NH4F and the reaction temperatures. The present study has enlarged the family of 3D solid microspheres, and offers a possible route for the synthesis of other inorganic hierarchical structures.