A Sucrose-Derived Copper Oxide/Polyurethane Foam for Efficient and Sustainable Solar-Driven Seawater Desalination

Solar-driven interfacial evaporation technology represents a transformative approach for addressing the pressing challenge of global freshwater scarcity, leveraging localized photothermal conversion mechanisms to achieve high-efficiency, sustainable water production. Currently, the solar interface evaporation technology encounters three significant challenges in the process of large-scale application: the restricted evaporation rate, performance attenuation resulting from salt crystallization, and nonrecyclability of the specific evaporation device. To address the intrinsic constraints of existing solar-driven desalination technologies, this work introduces a copper-oxide-functionalized biodegradable polyurethane (CuO/PU) composite foam, fabricated through a single-step synthesis method. The engineered material exhibits superior mechanical robustness and optimized photothermal conversion efficiency, positioning it as a viable candidate for sustainable, large-capacity freshwater generation. The CuO/PU composite foam exploits the narrow-band-gap semiconductor characteristics of CuO to achieve broad-spectrum solar energy harvesting while retaining good hydrophilicity (water contact angle: 12.7°), thereby enabling highly efficient solar-driven interfacial evaporation. The temperature of the CuO/PU composite foam can reach 102.5 °C under laser irradiation, while it can reach 74.6 °C under simulated sunlight (1 kW m–2). The evaporation rate of the CuO/PU foam is 1.79 kg m–2 h–1, and the water evaporation efficiency (η) can reach 92%, demonstrating a 297% enhancement over unmodified PU foam. In addition, the CuO/PU foam presents a great self-cleaning performance in saline water. On the whole, the CuO/PU foam exhibits great potential in a large-scale solar-driven water evaporation system, contributing to its highly efficient photothermal conversion effect and self-cleaning performance.