Effect of Cation Exchange Time on the Morphology and Photoactivity of CdS/Ag2S Composites for Ciprofloxacin Degradation

Abstract

Herein, the effect of reaction time in the cationic exchange method on the CdS/Ag2S structure and photocatalytic activity is investigated. A hydrothermal approach is used to produce CdS nanorods, and then a cation exchange method is applied to synthesize CdS/Ag2S composites. The heterostructure between CdS and Ag2S is determined by the X‐ray diffraction and transmission electron microscopy studies. Comparing pure CdS NRs and CdS/Ag2S by the UV–vis diffuse reflection spectra data, the introduction of Ag2S is proven to enhance the light absorption in visible region. The Brunauer–Emmett–Teller method indicates that CdS and CdS/Ag2S are mesopore materials and the specific surface areas of CdS, CdS/Ag2S‐15, CdS/Ag2S‐30, and CdS/Ag2S‐60 samples without and with a cation‐exchange reaction time of 15, 30, and 60 min are 305, 900, 187, and 52 m2 g−1, respectively. The photocatalytic activity of CdS/Ag2S is examined through the ciprofloxacin photodegradation. The ciprofloxacin degradation rate increases with the introduction of CdS and reached a maximum value of 60% within 180 min for CdS/Ag2S‐15 under simulated sunlight irradiation, which is 1.5 times greater than that of pure CdS. The ciprofloxacin degradation rate decreases as the cation‐exchange reaction time is increased to 60 min (26% after 180 min illumination).