Solar interface photothermal evaporation is a promising strategy to ensure affordable water production. However, obtaining freshwater from wastewater containing highly concentrated volatile organic compounds (VOCs) is still a high hanker. Here, a polyvinyl alcohol (PVA)-based hydrogel evaporator was developed to mutually reinforce photothermal evaporation and photocatalytic degradation. The vertical structure promoted the rapid transfer of water molecules between the microchannels. Moreover, the solar absorption efficiency can be improved through multiple reflections. Furthermore, introducing polypyrrole (PPy) and MXene@TiO@g-CN (MTG) heterojunction can not only regulate the interaction force between the polymer network and water molecules to reduce the evaporation enthalpy, but also endow the PVA/PPy@MTG hydrogel with excellent photocatalytic degradation performance. Besides, the first principles simulation indicated that this hydrogel displayed higher binding energy for contaminants than water molecules. Therefore, it can achieve an evaporation rate of ∼3.0 kg m h and energy efficiency of ∼97.2 % under 1-sun, higher than the structure-disordered PVA/PPy@MTG hydrogel. In addition, it can degrade different complex components, especially for highly concentrated VOCs (100 ppm) with an efficiency of >94.2 %, exceeding most of the reported integrated evaporators. This work will pave a potential pathway to design novel evaporation for sustainable water remediation.

中文翻译：

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受向日葵启发的水凝胶蒸发器，蒸发和光降解相互增强，用于综合水管理

太阳能界面光热蒸发是确保负担得起的水生产的一种有前景的策略。然而，从含有高浓度挥发性有机化合物（VOC）的废水中获取淡水仍然是一个迫切的需求。这里，开发了一种基于聚乙烯醇（PVA）的水凝胶蒸发器，以相互增强光热蒸发和光催化降解。垂直结构促进了水分子在微通道之间的快速转移。此外，通过多次反射可以提高太阳能吸收效率。此外，引入聚吡咯（PPy）和MXene@TiO@g-CN（MTG）异质结不仅可以调节聚合物网络与水分子之间的相互作用力以降低蒸发焓，而且还赋予PVA/PPy@MTG水凝胶优异的光催化降解性能。此外，第一性原理模拟表明，这种水凝胶对污染物的结合能比水分子更高。因此，它在1-sun下可以实现~3.0 kg·m·h的蒸发速率和~97.2%的能量效率，高于结构无序的PVA/PPy@MTG水凝胶。此外，它可以降解不同的复杂组分，特别是对于高浓度的VOC（100 ppm），效率>94.2%，超过了大多数报道的集成蒸发器。这项工作将为设计新型蒸发以实现可持续水体修复铺平道路。