Heterostructural BiOI/TiO2 Composite with Highly Enhanced Visible Light Photocatalytic Performance

Binary BiOI/TiO2 hybrid material was synthesized via a sol-gel method combined with chemical etching. The as-prepared powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DRS), photoluminescence spectra (PLS) and photocurrent response tests. Under visible light (lambda > 420 nm), BiOI/TiO2 degraded methyl orange (MO) efficiently and displayed much higher photocatalytic activity than that of pure BiOI. Moreover, BiOI/TiO2 can effectively promote photooxidation of other organic dyes like rhodamine B (RhB), crystal violet (CV) and methylene blue (MB). In addition, the quenching effects of different scavengers proved that reactive O-2(+) and h(+) played the major role in the MO degradation. The photocatalytic activity enhancement of BiOI/TiO2 is closely related to the strong absorption in the visible region, and the efficient charge separation derived from the matching band potentials between BiOI and TiO2, as well as the low recombination rate of the electron-hole pairs due to the heterojunction formed between BiOI and TiO2.