Enhanced visible light photocatalytic activity of BiOI/BiOCOOH composites synthesized via ion exchange strategy

The BiOI/BiOCOOH composites were synthesized by a facile ion exchange strategy between BiOCOOH precursor and KI by ultrasonic reaction. The as-prepared BiOI/BiOCOOH composites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance absorption spectra (DRS), Fourier transform infrared spectroscopy (FTIR) and photoluminescence spectra (PL). Under visible light illumination, the BiOI/BiOCOOH composites exhibited much higher photocatalytic activities than those of single BiOCOOH and BiOI for the degradation of Rhodamine B (RhB). The markedly enhanced photocatalytic activities of BiOI/BiOCOOH composites were attributed to the formation of a p-n heterojunction between p-type BiOI and n-type BiOCOOH, which facilitated the charge separation of photogenerated electron-hole pairs. The photoelectrochemical measurement confirmed that the charge separation efficiency was greatly improved by the formation of the heterojunction structure. Moreover, tests of radical scavengers demonstrated that h(+) and O-center dot(2)- were the main active species for the degradation of RhB.