▎ 摘　　要

NOVELTY - Composite hydrogel sponge comprises water supply layer and evaporation layer that are stacked successively; the material of water supply layer is polyacrylamide hydrogel; the material of evaporation layer is polyacrylamide/graphene composite hydrogel; the polyacrylamide/graphene composite hydrogel includes polyacrylamide hydrogel and graphene dispersed in the polyacrylamide hydrogel. USE - The composite hydrogel sponge is useful in field of seawater desalination. ADVANTAGE - The composite hydrogel sponge: has unique porous structure, which is beneficial to the rapid transmission and supply of water; at same time, graphene on the surface of the evaporation layer can fully receive solar energy, produces higher photothermal conversion efficiency. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: Preparing the composite hydrogel sponge comprising mixing the first acrylamide, first initiator, first auxiliary initiator, first cross-linking agent and first water, and performing the first in-situ polymerization in mold to obtain a polyacrylamide hydrogel layer; mixing second acrylamide, second initiator, second auxiliary initiator, second cross-linking agent, graphene and second water, performing second in-situ polymerization on upper surface of polyacrylamide hydrogel layer to form a polyacrylamide/graphene composite hydrogel layer, and obtaining composite hydrogel sponge. Solar-powered seawater desalination device comprises a concentrating system, first convex lens and a solar evaporator arranged in sequence; the light reflected by the light collecting system is irradiated on the solar evaporator through the first convex lens; the light collecting system includes a concave reflector, a second convex lens and a plane reflector which are sequentially arranged from bottom to top; the centers of the concave mirror, the second convex lens and the plane mirror are located on the same straight line; the line is perpendicular to the horizontal plane; the solar evaporator comprises the composite hydrogel sponge; also includes inverted ''V'' shaped transparent glass cover and stand; the stand includes a seawater area in the middle and a freshwater collection area at both ends; the composite hydrogel sponge floats on the seawater surface of the seawater area.