Facile synthesis of p-n heterojunction of phosphorus doped TiO2 and BiOI with enhanced visible-light photocatalytic activity

TiO2/BiOI heterostructures were prepared with BiOI nanosheets and phosphorus-doped TiO2 nanoparticles by a facile method at a low temperature. X-ray diffraction, scanning electron microscopy, UV-vis diffuse reflectance spectra and X-Ray Photoelectron spectroscopy were employed to characterize the phase structures, morphologies and optical absorption properties of TiO2/BiOI p-n heterojunction. The experimental results show that BiOI nanoplates and TiO2 nanoparticles bind through chemical bonds rather than a simple mixture of the two materials. The optical absorption edge of TiO2/BiOI heterostructures was extended to more than 650 nm in visible-light region. The samples exhibited higher photocatalytic activity than pure BiOI and TiO2 for the degradation of Rhodamine B under the irradiation of visible light. In addition, the photocatalytic mechanism of TiO2/BiOI heterostructures has also has been investigated in the presence of active species scavengers. The photocatalytic activity enhancement of TiO2/BiOI heterostructures could be attributed to the synergistic effect of the strong absorption in the visible region and low recombination rate of the electron-hole pairs because of the p-n heterojunction of BiOI naosheets and P-doped TiO2 nanoparticles.