Synthesis and study of Bi 2 Ti 2 O 7 /TiO 2 composites as efficient visible-light-active photocatalysts in the reduction of aqueous Cr(VI)

Abstract

Abstract In this work, Bi2Ti2O7/TiO2 composites were synthesized and studied as potential visible-light-activated photocatalysts in the reduction of aqueous Cr(VI). Bi2Ti2O7/TiO2 composites with tunable compositions were synthesized via a solvothermal-calcination two-step method, simply by changing the molar ratios of Bi(NO3)3·5H2O to tetrabutyl titanate in the reactants. The compositions, structures and optical properties of the as-synthesized Bi2Ti2O7/TiO2 composites were characterized by X-ray diffraction, field emission scanning electron microscopy and UV–vis diffuse reflectance spectra. The photocatalytic activity of the as-synthesized Bi2Ti2O7/TiO2 composites was tested in the reduction of aqueous Cr(VI) under visible-light (λ > 420 nm) irradiation, and compared with that of TiO2 nanoparticles. It was observed that the as-synthesized Bi2Ti2O7/TiO2 composites exhibited much higher photocatalytic activity than TiO2 nanoparticles, and the most efficient composite (300 mg) can achieve the complete reduction of Cr(VI) in 300 mL of 50 mg/L K2Cr2O7 aqueous solution under visible-light (λ > 420 nm) irradiation in 90 min.