All-Day Freshwater Harvesting through Combined Solar-Driven Interfacial Desalination and Passive Radiative Cooling

Solar-driven interfacial evaporation has received increasing research attention for clean water generation, but freshwater harvesting often occurs only during daytime. Herein, we report a strategy for all-day freshwater harvesting through combining solar-driven interfacial desalination and dew water generation. Through spray-coating carbon nanotubes onto a flexible substrate that has high-infrared emittance in the atmosphere window, a dual functional film was prepared to efficiently absorb solar energy for desalination at daytime and passively cool down the surface temperature to collect dew water at night. By integrating the dual functional film within a three-stage membrane distillation device, the home-made system achieved a drinkable freshwater collection efficiency of 71.1% when desalinating seawater under 1 sun illumination and achieved a dew water collection rate of 0.1 L m–2 day–1 at night. The readily available low-cost raw materials, simple fabrication process of the dual functional films, and the resultant all-day freshwater collection systems make the combined solar-thermal interfacial desalination and dew water collection a promising solution to alleviate the freshwater shortage in many underdeveloped regions, arid areas, and islands.