Hierarchically designed evaporators with dual-layered hydrogel/aerogel structure for efficient solar water evaporation

Solar water evaporation technology is now emerging rapidly as it realizes low-cost desalination by utilizing sunlight as energy source. However, many researches focused only on the performance of specific systems, while ignoring the universality and compatibility of their evaporator designs. Herein, molecular dynamic simulations were performed to select and predict the performance of photo-thermal conversion (PTC) materials before carrying out experiments. As MoS2 and TiN were predicted to have promising evaporation performance, hierarchical evaporators composed of upper hydrogel layers and ice-templated aerogel substrates were fabricated. By reducing water evaporation enthalpy, the highest evaporation rate of 1.61 kg m-2 h-1 was achieved in CSSA-TiN under 1.0 sun illumination. Owing to the hierarchical design and ice-templated substrate, local dual-layered hydrogel/aerogel structures and vertically aligned channels were constructed in the evaporators, which guarantees the structural integrity and the backflow of salts during evaporation. Our work provides comprehensive insights into the selection of PTC materials, the prediction of their performance, and the construction of evaporators.