Preparation and Photocatalytic Activity of Ag2S/ZnS Core–Shell Composites

Ag2S/ZnS core–shell composite microspheres were successfully synthesized via a simple two-step hydrothermal process, in which Ag+ ions might replace Zn2+ ions on the surface of ZnS microspheres via an ion exchange, and subsequently form Ag2S nucleus on the surface of the microspheres. The effect of Ag2S content on the structure, morphology and optical properties of the material was studied in detail. We found that the photocatalytic efficiency of Ag2S/ZnS composites for the degradation of Rhodamine B (RhB) aqueous solution is much higher than that of pure ZnS or Ag2S under solar-simulated light irradiation, which is considered that the combination of a narrow band gap with a wide band gap semiconductor can timely transfer photogenerated electron–hole pairs and rapidly separate photogenerated electrons and holes. Moreover, the catalytic activities of the 4%Ag2S/ZnS sample for oxidation and decomposition of RhB with the assistance of hydrogen peroxide are enhanced with an increase of the degradation efficiency from 68.8 to 90.0% at room temperature.