Water scarcity has become a global problem and caused a lot of conflicts. Atmospheric water harvesting (AWH) is a promising way to address water shortage issue. However, traditional adsorbent materials such as silica gels and zeolites suffer from low water productivity and high regeneration temperature. Hygroscopic salts like LiCl are regarded as a perspective substitution. Salt-modified metal organic frameworks (MOFs) and hydrogels are employed to alleviate the salt aggregation but they are limited to expensive fabrication or sluggish adsorption kinetics. Herein, we demonstrate an asymmetric double-layer design of LiCl@CC (carbon cloth)/PAM with separated function of water adsorption/desorption and water storage in different layer. This double-layer design not only enhances the mechanical properties but also shows an improved water adsorption kinetics compared to common salt-composite hydrogels. In experimental test, the LiCl@CC/PAM exhibits excellent water uptake of 1.5 g g under 60 % RH in 4 h and fast water desorption under sunlight in 1.5 h. In outdoor test, LiCl@CC/PAM based device presents a daily water uptake of 5.12 g g day. Meanwhile, all the materials used and fabrication process are feasible to scale up, which provides a possible solution to the global crisis of water scarcity.

中文翻译：

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LiCl@CC/PAM的不对称双层设计可高效从大气中吸水

水资源短缺已成为一个全球性问题，并引发了很多冲突。大气水收集（AWH）是解决水资源短缺问题的一种有前景的方法。然而，硅胶、沸石等传统吸附材料存在产水率低、再生温度高等问题。像 LiCl 这样的吸湿盐被认为是一种透视替代品。盐改性金属有机框架（MOF）和水凝胶被用来减轻盐聚集，但它们仅限于昂贵的制造或缓慢的吸附动力学。在此，我们展示了LiCl@CC（碳布）/PAM的不对称双层设计，不同层具有分离的水吸附/解吸和储水功能。与普通盐复合水凝胶相比，这种双层设计不仅增强了机械性能，而且还表现出改善的水吸附动力学。在实验测试中，LiCl@CC/PAM在60%RH下4小时内表现出优异的吸水率，达到1.5 g g，在阳光下1.5小时内快速解吸水。在户外测试中，基于 LiCl@CC/PAM 的装置每日吸水量为 5.12 g g。同时，所有使用的材料和制造工艺都可以放大，这为解决全球水资源短缺危机提供了可能的解决方案。