Surface Engineering of 3D Solar Evaporator for Uncompromising Water Evaporation and Salt Production Toward High Concentration Brine

Abstract Solar‐driven interfacial evaporation toward highly salinity brine has drawn great attention due to its distinct advantages. Generally, most studies focus on how to improve the water evaporation rate while restrain the salt accumulation on evaporators. In fact, generating/recycling the salt during the evaporation process is of equal importance since the salt is also valuable. However, how to realize high salt generation rate while keep high water evaporation rate is still a great challenge, since high‐efficiency water evaporation and salt accumulation is conflicting in most cases. Herein, both high evaporation rate and high salt formation rate have been achieved via surface engineering of a 3D evaporator: 1) Constructing surround‐Janus structure with different wettability around a 3D evaporator; 2) Enhancing salt crystallization via introduction of tapes on special surface. Thanks to the distinct surface engineering, the water evaporation rate toward highly salinity brine (20 wt%) can reach up to ≈2.8 kg m −2 h −1 , while the salt formation rate can be as high as ≈0.1 kg m −2 h −1 . Moreover, the high performance can be well maintained even when the evaporator is irradiated with different angles. Specially, as a proof of concept, the potential of the 3D evaporator for Li + /Na + separation is also demonstrated.