Preparation, characterization and photocatalytic degradation properties of Zn0.5Cd0.5S/SnO2 composites

The Zn0.5Cd0.5S/SnO2 composite photocatalyst was synthesized via a hydrothermal method. The crystal phase, micromorphology, optical and photoelectric property as well as surface elements valence were characterized using X-ray diffraction, field emission scanning electron microscope, transmission electrical microscope, UV–Vis diffuse reflectance spectrometer, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy, respectively. Tetracycline was used to discuss the photocatalytic properties of the samples under visible light irradiation. Research results indicate that the as-synthesized Zn0.5Cd0.5S/SnO2 composite photocatalysts show better photocatalytic performance than that of pure samples. Moreover, the photocatalytic activity of the as-synthesized composites presents first increased and then decreased with increasing the amount of SnO2 in the composites. When the quality ratio of SnO2 to Zn0.5Cd0.5S is 7%, in 60 min, the as-synthesized composites reveal the best photocatalytic degradation efficiency of 92.9%, which is high than 85% of Zn0.5Cd0.5S and 0% of SnO2. This is ascribed of the improvement of the separation efficiency of photo-generated electron–hole pairs and the transmission rate of electrons. Furthermore, the decomposition mechanism of as-synthesized composites for tetracycline was also provided. The holes and superoxide radicals play crucial species in the photocatalytic degradation process.