Water Skin Effect and Arched Double‐Sided Evaporation for Boosting All‐Weather High Salinity Desalination

Abstract

AbstractHigh efficiency, long‐term salt rejection, and continuous operation under all‐weather conditions have always been the goals of solar‐driven desalination of high salinity brine. Here, a synergistic strategy of water skin effect and double‐sided evaporation is proposed by an arched evaporator to overcome the above issues. Specifically, a hydrophobic carbon‐fiber cloth (CC) is coated with metal‐organic framework (MOF)‐derived superhydrophilic carbon films, and bent into an arch‐like configuration. Due to unique hydrophobic‐core/hydrophilic‐shell structure, an ultrathin water film (30–150 µm) is confined to the outer layer like skin. Thanks to the water skin effect and coevaporation of outer and inner surfaces, the arched evaporator displays ultrahigh evaporation rate of 3.21 kg m−2 h−1 (3.5 wt% NaCl) and 2.87 kg m−2 h−1 (20 wt% NaCl) under 1 sun illumination. Simultaneously, the free‐flowing water skin with fast convection for salt rejection, ensures stable evaporation performance during the whole day. Additionally, an evaporation rate up to 3.5 kg m−2 h−1 is acquired with only 2.5 V input voltage in a dark environment, attributable to the superior electrothermal effect of CC. The constructed evaporator with all‐in‐one function provides an effective way for commercial, portable photothermal conversion to achieve seawater purification.