Solar-driven interfacial desalination is an emerging approach to address global freshwater crisis while minimizing carbon emissions. A key challenge in interfacial desalination technology is maintaining long-term high efficiency with fouling-resistance and energy-saving. Here, we develop a 3D-printed concave-shaped solar evaporator and a floating freshwater collection setup, that achieve nearly 100% photothermal evaporation efficiency with a rate of 2.23 \({{{\rm{kg}}}}{{{{\rm{m}}}}}^{-2}{{{{\rm{h}}}}}^{-1}\) and freshwater collection rate of 1.23 \({{{\rm{kg}}}}{{{{\rm{m}}}}}^{-2}{{{{\rm{h}}}}}^{-1}\) under one sun illumination. This 3D concave-shaped solar evaporator design, achieved through 3D printing and double-sided surface modification, allows interfacial desalination process to occur at the bottom surface of the evaporator with superior heat transfer, ultra-effective salt-resistance and enlarged water-air interfacial area. The evaporation stability, extending well beyond traditional limitations of days or months, is realized by a decoupling design and the low-cost renewal of water-intake layer. This design allows vapor to escape downward without causing fouling problem within the top solar absorber. Furthermore, a self-floating freshwater collection setup facilitates thermal exchange with low-temperature seawater for sustainable application. Our large-scale integrated 3D printed evaporator-collector strategy demonstrates potential for portable solar-driven interfacial desalination and freshwater collection.
