Facile phase control for hydrothermal synthesis of anatase-rutile TiO2 with enhanced photocatalytic activity

Mixed-phase TiO2 photocatalysts with different proportions of anatase and rutile have been successfully synthesized in an acidic hydrothermal system, using tartaric acid (C4H6O6) as a phase content regulator and titanium trichloride (TiCl3) as the titanium source. The obtained samples were characterized by X-ray diffraction spectroscopy (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM) and so on. The phase contents of anatase and rutile in the TiO2 particles were successfully controlled by simply adjusting the molar ratio of C4H6O6 to TiCl3. And the regulation degree could be further controlled by the concentration of sodium chloride (NaCl) in the reaction system. In addition, the effect of the reaction time, hydrothermal temperature and acidity on the phase structure of as-prepared products have also been investigated. A mechanism was proposed to interpret the evolution of the phases based on the experimental results. Finally, the photocatalytic activity of the prepared TiO2 were evaluated by the degradation of Rhodamine B (RhB) and methyl orange (MO) in aqueous solutions. The mixed-phase TiO2 exhibited higher activity than pure phase TiO2, and the catalyst containing 77% anatase and 23% rutile had the highest photocatalytic activity. The enhanced photocatalytic activity could be explained by the mixed-phase effect between anatase and rutile. (C) 2015 Elsevier B.V. All rights reserved.