One-pot low-temperature synthesis of BiOX/TiO2 hierarchical composites of adsorption coupled with photocatalysis for quick degradation of colored and colorless organic pollutants

Abstract BiOX/TiO2 (X = Cl, Br, and I) hierarchical composites with superior photoelectrochemical performances were successfully synthesized by one-pot low-temperature solvothermal process without any structure-directing agents. The dual functions of adsorption coupled with photocatalysis based on BiOX/TiO2 were fully exhibited in terms of the quick degradation of colored and colorless organic pollutants (OPs). The as-prepared composites were characterized by field-emitting scanning electron microscope (FESEM), X-ray power diffraction (XRD) analysis, transmission electron microscope (TEM), N2 adsorption/desorption, UV–vis diffuse reflectance spectra (DRS), photoluminescence spectra (PL), photocurrent measurements (PC), and electrochemical impedance spectroscopy (EIS), respectively. As-prepared BiOX/TiO2 composites exhibited outstanding photoelectrochemical activities. Especially, the considerably enhanced adsorption and photocatalytic efficiencies were observed in the optimized BiOCl/TiO2 composites compared to their counterparts. The improvement of adsorption and photocatalytic performances should be ascribed to the presence of columbite TiO2-II in anatase, which would not only improve the ability of absorbing visible light and the charge separation efficiency, but also to effectively tailor the particle size, surface area and the exposed active facet of composites.