Hydrophilic Polymer Foam as a Monolithic Interfacial Solar Evaporator With Rapid Self‐Cleaning, High Evaporation Efficiency, and Salt Resistance

Abstract Manufacturing a multilayer evaporator with a delicate structure and removing salt accumulation during prolonged operation are challenges in seawater desalination. A flexible single‐layer salt‐rejecting monolithic porous evaporator (SRMPE) is presented that floats on the near surface of seawater without any support structure. The hydrophilic component of this network polymer modulates the water association state in SRMPE, achieving a high evaporation rate of 3.47 kg m −2 h −1 and an efficiency of 94.3%. With a large capillary water flux (14.4 L m −2 h −1 ), the SRMPE exhibits superior and rapid self‐cleaning by removing sodium chloride (NaCl) powder (33% by weight) within 1.25 h in simulated seawater (salinity, 3.5%) under 1 sun radiation. Furthermore, even after continuous irradiation for 12 h in highly concentrated brine (25% salinity), no salt crystallizes on the evaporator surface. It may stimulate creative work by scientists and engineers in the design of simple, highly efficient salt‐rejecting, self‐cleaning interfacial solar evaporators.