Synthesis of BixTiyOz/TiO2 heterojunction with enhanced visible-light photocatalytic activity and mechanism insight

Four bismuth titanate and titania composites were firstly synthesized by the mixed alcohol-thermal method using same material ratio. The as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Energy dispersive X-ray spectrometry (EDS), Ultraviolet–visible (UV–Vis), Brunauer-Emmett-Teller (BET) surface area test and Photocurrent response curve. The results indicated that the composition and morphology of composites were affected by the glycerol ratio and calcination temperature. The mineralized rate of titanium salt and bismuth salt could be adjusted by the proportion of glycerol, which changed the ratio of titanium oxide to bismuth oxide in the system and formed the different bismuth titanate composites. The photodegradation efficiency of tetracycline hydrochloride (TC), chlortetracycline hydrochloride (CTC) and methylene blue (MB) by the as-prepared composites were greater than that of pure TiO₂ under visible light. The free radical trapping experiments also proved that superoxide ion radicals (·O₂⁻) and holes (h⁺) played a leading role in photocatalytic degradation, and the possible photocatalytic degradation mechanism of the composites was also discussed.