▎ 摘　　要

NOVELTY - Composite film material comprises a water transport layer and a light absorbing layer from bottom to top, where the light absorbing layer is attached to one side of the water transport layer, the water transport layer has a first pore structure, and the light absorbing layer has a second pore structure, the first pore structure communicates with the second pore structure, and the pore diameter of the first pore structure is larger than the pore diameter of the second pore structure. USE - Composite film material used in a solar evaporator for desalting seawater treatment (claimed) and to industrial wastewater and domestic sewage. ADVANTAGE - The composite film materia has high energy utilization rate and serious salt of photo-thermal conversion. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for preapring a composite film material, which involves: a. curing the semi-solidified polymer hydrogel to obtain a cured polymer hydrogel; b. coating a light-absorbing material containing flake-like nano-materials on one side of the cured polymer hydrogel to form a light-absorbing material layer to obtain a primary product; c. subjecting initial product to liquid nitrogen freezing treatment, so that the water in the polymer hydrogel forms ice crystals, the size of the ice crystals used to form the first pore structure is controlled by adjusting the freezing time, and then freeze-drying, the sublimation of ice crystals in polymer hydrogel to form water transport layer having the first pore structure; and d. adjusting the freeze-drying treatment time so that the flake-shaped nano raw materials in the light-absorbing material layer are stacked layer by layer to form the light-absorbing layer with the second pore structure.