Template-free synthesis of three-dimensional porous CdS/TiO2 with high stability and excellent visible photocatalytic activity

A novel stereo porous and highly stable photocatalyst CdS/TiO2-400 (composite CdS/TiO2 calcined at 400 °C) was synthesized by hydrolysis-hydrothermal-calcined method without the assistance of template. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), ultraviolet–visible diffuse reflectance spectra (UV–vis DRS), transient photocurrents, photoluminescence emission spectra (PL) and Brunauer-Emmett-Teller (BET) to study their crystallinity, morphologies, structure, optical properties and specific surface area. The experimental results validated that as-prepared CdS/TiO2-400 could effectively improve the separation efficiency of photogenerated electron-hole pairs and displayed superior photocatalytic activity in the degradation process of methyl orange (MO), oxytetracycline (OTC) and tetracycline (TC). The promoted photocatalytic activity was attributed to the calcination procedure and high specific surface area. A possible photocatalytic mechanism of CdS/TiO2-400 was proposed on the basis of trapping experiments.