Simultaneous Salt Rejection and Heat Localization Via Engineering Macrochannels in Morning Glory‐Shaped 3D Evaporator

Abstract Solar desalination is a promising solution for alleviating water scarcity due to its low‐cost, environmentally friendly, and off‐grid capabilities. However, simultaneous salt rejection and heat localization remain challenging, as the rapid salt convection often results in considerable heat loss. Herein, this challenge is overcome via a facile design: i) isolating high‐temperature and high‐salt zones by rationally designing morning glory‐shaped wick structures and ii) bridging high‐salt zones and bulk water with low‐tortuosity macrochannels across low‐temperature surfaces. The salinity gradient in the macrochannels passively triggers convective flow, facilitating the rapid transfer of salt ions from the high‐salt zone to the bulk water. Meanwhile, the macrochannels are spatially isolated from the high‐temperature zone, preventing heat loss during salt convection and thereby achieving a high evaporation rate (≈3 kg m−2 h−1) and superior salt rejection even in highly concentrated real seawater. This work provides new insights into salt rejection strategies and advances practical applications for sustainable seawater desalination.