Precisely Ultrafast Laser‐Controlled Multilevel Photothermal Well Arrays for Rapid and Salt‐Tolerant Solar Desalination

Abstract Solar‐driven interfacial water evaporation is pivotal in alleviatingfreshwater crisis. However, simultaneously preserving both high water evaporation rates and robust salt resistance remains an important challenge due to insufficient precise control over interfacial multilevel structures in solar evaporators. Inspired by sunflower Fibonacci spiral patterns, a 3D solar evaporator is developed with precisely ultrafast laser‐controlled multilevel photothermal well arrays (PWSE) for rapid, salt‐tolerant desalination. The approach utilizes ultrafast laser processing technology to create precisely controlled micro/nanostructures on both sides of copper substrates, serving as multilevel photothermal well arrays for omnidirectional light absorption. The tightly and uniformly arranged sunflower‐like Fibonacci spiral patterns on PWSE surface create a natural self‐lifting water pathway and a thin water film for rapid evaporation. When vertically positioned in a solar distiller, PWSE reduces device footprint and significantly enhances the water evaporation rate of 3.58 kg m −2 h −1 (one sun). PWSE demonstrates excellent salt‐resistant performance under gravity‐driven salt particle shedding, and can be employed for clean water harvesting with an optimized capacity of 15.59 kg m −2 day −1 in summer outdoor environments. This work highlights micro/nanomaterials engineering of solar evaporatorsfor water and energy sustainability.