Cation exchange synthesis of ZnS-Ag2S microspheric composites with enhanced photocatalytic activity

► ZnS-Ag2S composite microspheres were synthesized via a two-step hydrothermal method for the first time. ► Ag2S deposition was resulted from cation exchange due to the large difference in solubility. ► AgNO3 concentration had obvious effects on structure, microstucture and photocatalytic activity. ► Ag2S modified ZnS composite showed greatly enhanced photocatalytic performance.