▎ 摘　　要

NOVELTY - Photocatalytic thin film comprises a film substrate and at least two modification layers coated on the outer surface of the film substrate. The modification layer comprises a first photocatalytic material layer, a graphene oxide layer and a second photocatalytic material layer which are connected alternately from the inside to the outside. The photocatalytic material comprises strontium sulfate core, strontium carbonate coated on the outer surface of the strontium sulfate core, and strontium titanate coated on the outer surface of the strontium carbonate. USE - The photocatalytic film is useful for redox reaction of pollutants in water body (claimed). ADVANTAGE - The photocatalytic film has good photocatalytic activity through the cooperation of photocatalytic materials and graphene oxide. The method has simple process, and suitable for industrial application. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparation method of photocatalytic thin film, comprising (1) soaking the film substrate into polyvinyl alcohol solution, and drying to obtain pre-treated film, (2) soaking the pre-treated film obtained in the step (1) into the trimesoyl chloride solution for the first modification, dipping into the photo-catalytic material dispersion for the second modification, washing, and drying to obtain the first film, (3) soaking the first film obtained in the step (2) into the trimesoyl chloride solution for third modification, and drying to obtain the second film, (4) immersing second film into the oxide dispersion graphene for the fourth modification, and drying to obtain the third film, (5) soaking the third film obtained in the step (4) into the photo-catalytic material dispersion liquid for fifth modification, and drying to obtain the fourth film, and (6) repeating the step (3)-(5) on the fourth film obtained in the step (5) to obtain composite film material, and using ultraviolet light to irradiate the composite film material to obtain the photo-catalytic film.