Annealing effects on photocatalytic activity of ZnS films prepared by chemical bath deposition

► ZnS thin films have been prepared by chemical bath deposition. ► The effects of annealing on the optical properties of ZnS films were investigated. ► The adsorption band wavelength of ZnS films red-shifts with increasing annealing temperature or heating rate. ► Heat treatment can effectively enhance the photoactivity of ZnS films.