Advanced Multi-functional polyurethane sponge with excellent salt Resistant, Antifouling and Oil-Water separation capabilities for highly efficient and Persistent solar desalination

Continuous and efficient seawater evaporation is paramount for sustainable solar-powered freshwater production. However, current solar-powered desalination plants face challenges such as salt accumulation, oil spills, or marine fouling, resulting in operational issues like clogging and corrosion. Hence, there is an urgent need to develop a robust freshwater generation device capable of preventing multiple contaminations. In this paper, a novel multilayer structured composite polyurethane sponge (CDPU) consisting of a photothermal layer (PTPU), a salt and marine fouling-resistant layer (SDPU), and an oil–water separation layer (LPPU) was developed through a straightforward surface coating method. Initially, CDPU efficiently separates oil pollutants from seawater and reclaims spilled oil via the LPPU layer. Subsequent purification is facilitated by the exceptional anti-fouling properties of the SDPU layer, preparing the seawater for desalination via the photothermal layer. This integrated approach boosts the water evaporation rate to approximately 2.22 kg/m 2 ·h with a remarkable photothermal conversion efficiency of 91.9 %. Notably, the CDPU exhibits impeccable resistance (99.99 %) against E. coli and S. aureus and excellent resistance to diatom adhesion. In addition, when augmented with Fe 3 O 4 @OA@HCNT nanoparticles, the CDPU demonstrates exceptional prowess in separating and recovering oil spills from seawater. Thus, CDPU emerges as a promising candidate for solar-powered desalination.