Hydrothermal synthesis of BiVO4/TiO2 composites and their application for degradation of gaseous benzene under visible light irradiation

Benzene is currently recognized as one of the most toxic contaminants. Our previously published study revealed that BiVO4/TiO2 is an excellent photocatalyst toward the degradation of benzene. Herein, BiVO4/TiO2 has been synthesized via a sol-gel method and a facile hydrothermal route by adjusting the precursor hydrolysis rate with the use of different acids (CH3COOH, HNO3 and H2SO4). The influence of these acids on the physicochemical characteristics and photocatalytic performance is discussed in detail. X-ray diffraction and N-2 sorption analyses confirm that acid has an important effect on the crystalline composition and BET specific surface area. BiVO4/TiO2 synthesized in CH3COOH has better photocatalytic activity for the degradation of gaseous benzene than that in HNO3 and H2SO4 under visible light irradiation. Results of XPS measurement demonstrate that the hydroxyl group in BiVO4/TiO2-CH3COOH is more abundant than that in BiVO4/TiO2-HNO3 and BiVO4/TiO2-H2SO4. The photocurrent signal is investigated by electrochemical measurement, which indicates that more effective separation of photogenerated carriers occurs in the BiVO4/TiO2/CH3COOH system. It is hoped that our work can offer valuable information on the design of TiO2 composites with enhanced properties. (C) 2017 Elsevier B.V. All rights reserved.