Spatial Decoupling of Water Evaporation and Salt Crystallization via a 3D Discrete Wettability Patterned Architecture

ABSTRACT Solar‐driven desalination offers a sustainable approach to treating high‐salinity brines, but the spatial coupling of water evaporation and salt crystallization in traditional evaporators causes performance degradation, and complex fabrication further limits large‑scale deployment. Here, we present a scalable strategy to construct a 3D discrete wettability patterned (DWP) architecture that spatially decouples water transport, interfacial evaporation, and salt crystallization, enabling efficient freshwater production and automatic salt collection from high‑salinity brine. Within the DWP architecture, superhydrophilic regions ensure continuous brine transport, while adjacent superhydrophobic regions form contact lines that enhance local evaporation. Together with the resulting temperature gradient between adjacent regions, these effects promote directional salt crystallization at hydrophilic‐hydrophobic boundaries. Continuous lateral crystal growth increases the gravitational torque, while sustained wetting at the crystal base weakens interfacial adhesion, together enabling spontaneous salt detachment through a torque‑balance mechanism. During a 168‐h continuous desalination test with 20 wt.% brine, the DWP evaporator achieves an evaporation rate of 3.51 kg m −2 h −1 and a salt collection rate of 0.51 kg m −2 h −1 . This work establishes a general architectural principle based on spatial decoupling to integrate efficient evaporation, automatic salt harvesting, and long‑term stability, advancing solar desalination from passive salt‐rejection toward maintenance‑free resource recovery.