Getting distilled water through solar energy is a green and sustainable way to purify water. The reduction of the evaporation enthalpy by hydrogels greatly improves the efficiency of water purification. However, the lack of heat localization functionality leads to low energy utilization efficiency, which seriously affects the performance of hydrogel-based evaporators. Herein, inspired by the hierarchical porous channel and thin structure of cormorant wings, a hydrogel thin film with interconnected micrometer macro-pores channels is proposed for simultaneous sufficient heat localization at the evaporation interface and adequate water supply. Benefiting from the macro-porous thin film structure, a device prepared from the hydrogel film can reduce the heat loss by 88% by reducing the heat transfer cross-sectional area and achieve a sustained water evaporation rate of 4.14 kg m⁻² h⁻¹ with 98% energy efficiency under 1 sun after shape optimization. Remarkably, the low raw material usage of thin film makes the cost as low as $0.87 m⁻². Furthermore, the synthesis method of this macro-porous thin film structure can be generalized to a range of hydrogels, thus serving as a universal technology for improving heat localization. This work demonstrates the application of macro-porous hydrogel thin film evaporators in green and sustainable water purification.

中文翻译：

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受鸬鹚启发的大孔水凝胶薄膜蒸发器，可提高太阳能水净化的成本效益

通过太阳能获取蒸馏水是一种绿色、可持续的净化水的方式。水凝胶降低蒸发焓，大大提高水净化效率。然而，热定位功能的缺乏导致能量利用效率低，严重影响了水凝胶蒸发器的性能。在此，受分层多孔通道和鸬鹚翅膀薄结构的启发，提出了一种具有互连微米级大孔通道的水凝胶薄膜，用于在蒸发界面同时实现充分的热量定位和充足的供水。受益于大孔薄膜结构，由水凝胶薄膜制备的装置可以通过减小传热截面积来减少88%的热损失，并实现4.14 kg m ^-2 h ^-1的持续水蒸发率形状优化后，1太阳光下的能源效率达到98%。值得注意的是，薄膜原材料使用量低，使得成本低至0.87 m ^-2美元。此外，这种大孔薄膜结构的合成方法可以推广到一系列水凝胶，从而成为改善热局部化的通用技术。这项工作展示了大孔水凝胶薄膜蒸发器在绿色和可持续水净化中的应用。