A Bionic‐Gill 3D Hydrogel Evaporator with Multidirectional Crossflow Salt Mitigation and Aquaculture Applications

Abstract In recent years, interfacial solar‐driven steam generation has gained huge attention as a sustainable and energy‐efficient technology. However, salt scaling on and inside the evaporator structure induced by insufficient ion distribution control will lower the evaporation performance and hinder the stability and durability of evaporators. Herein, inspired by the highly efficient salt‐expelling property of the gill filaments of large yellow croaker, a bionic‐gill 3D hydrogel evaporator is proposed with fabulous multidirectional ion migration controllability. A 3D structure composed of arrayed beaded hollow columns with beaded hollow holes inspired by gill filaments ensuring longitudinal ion backflow and the peristome‐mimetic arrayed grooves of microcavities ensuring lateral ion advection is designed and constructed to achieve fabulous multidirectional crossflow salt ion migration, which ensures high evaporation performance for pure water (an evaporation rate of 2.53 kg m −2 h −1 with an energy efficiency of 99.3%) as well as for high salinity brine (2.11 kg m −2 h −1 for 25.0 wt.% NaCl solution), with no salt crystallizing after long‐term use. Furthermore, the 3D hydrogel evaporator has excellent chemical stability, mechanical properties, folding‐irrelevant evaporation performance, and portability so that it can be used for the preliminary desalination of breeding wastewater through the proposed self‐circulation koi aquaculture system.