Novel BiOCl/TiO₂ hierarchical composites: Synthesis, characterization and application on photocatalysis

In this paper, a novel BiOCl/TiO₂ hierarchical composite was successfully synthesized by a facile one-pot solvothermal synthesis with the aid of polyvinylpyrrolidone (PVP). Then, the as-prepared composite was characterized by field-emitting scanning electron microscope (FESEM), transmission electron microscopy (TEM), N₂ adsorption/desorption, X-ray power diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (DRS) and electrochemical impedance spectroscopy (EIS), respectively. Research shows that this novel composite exhibits superior visible-light response, enhanced photoactivity and photostability for the formation of the BiOCl/TiO₂ heterojunctions. Especially, the rate constant of the photocatalyst with the molar ratio of anatase TiO₂ about 30% for decomposing RhB, can reach about 0.1510 min^-1, is far superior to commercial P25, as-prepared anatase TiO₂ nanoparticles and tetragonal BiOCl alone. In addition, the superoxide radicals (O^2-) and photogenerated holes (h⁺) were demonstrated to be the main active radicals in this photodegradation process. This study further reveals that the enhanced photoactivity of this photocatalyst should be ascribed to the successful formation of BiOCl/TiO₂ heterojunctions and the rapid migration of the interface charges.