Alkali-free synthesis of a novel heterostructured CeO2-TiO2 nanocomposite with high performance to reduce Cr(VI) under visible light

In this study, a novel CeO 2 -TiO 2 nanocomposite denoted as CeO 2 -3TiO 2 was successfully synthesized via a facile one pot hydro-thermal method without alkali. It exhibits high photocatalytic reduction reactivity toward Cr(VI) under visible light. The photocatalytic reactivity of CeO 2 -3TiO 2 is 18 times higher than that of pure CeO 2 , 28 times higher than pure TiO 2 , 15 times higher than the sample of simply mixed CeO 2 and TiO 2 . The solution with Cr(VI) initial concentration of 2780 ppb can be fast photoreduced by CeO 2 -3TiO 2 in 60   min under visible light to meet the criterion of U.S. Environmental protection Agency. Characterization results indicate CeO 2 -3TiO 2 has the good crystal form of heterojunction structure, narrow pore size distribution , narrow energy gap and high photogenerated electron-hole separation efficiency. Based on the experimental results, a speculated photocatalytic mechanism was proposed.