Strong visible absorption and excellent photocatalytic performance of brown TiO2 nanoparticles synthesized using one-step low-temperature process

We report a facile and modified sol-gel approach to synthesize brown TiO2 nanoparticles at low temperature (100-600 degrees C). The TiO2 nanoparticles dried at 180 degrees C (TiO2-180 degrees C) possessed a small particle size (5.0 nm), large specific surface area (213.45 m(2)/g), and efficient response to broadband light over the entire ultraviolet-visible spectrum with a narrow band gap of 1.84 eV. In addition, TiO2-180 degrees C exhibited the optimal reaction rate constant for the degradation of methylene blue (0.08287 mg/(L.min)), which is six times higher than that of the mixed rutile/anatase phase TiO2 photocatalytic standard P25 (0.01342 mg/(L.min)). Furthermore, cycling photodegradation experiments confirmed the stability and reusability of this catalyst. The unique physicochemical properties resulting from the low-temperature preparation of TiO2-180 degrees C, including its broadband visible absorption associated with a high concentration of oxygen vacancies, large surface area, and enriched surface -OH/H2O may be responsible for this excellent photocatalytic performance. The use of as-prepared TiO2-180 degrees C for practical applications is expected after further optimization. (C) 2017, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.