Schematic illustration of the composite adsorbent design and its proposed photothermal adsorption mechanism. The amidoxime functionalization of the polyethylene fiber was achieved via radiation-induced grafting, creating selective binding sites for uranium. Under solar irradiation, the loaded Ta₂O₅/C hollow multishelled structure efficiently converts light into localized heat. This heating promotes water evaporation and elevates the interfacial temperature, which in turn accelerates the diffusion of uranyl ions toward the adsorbent surface according to the Stokes-Einstein equation. The combined effects of thermally enhanced diffusion and selective chelation by amidoxime groups lead to significantly improved uranium adsorption kinetics.