Hydrogels with a low evaporation enthalpy and high water-molecule activation capability are regarded as promising substrate materials for solar-driven interfacial evaporation. However, the uncontrollable porous channels and cross-linking degree of traditional hydrogels limit water mass transportation, light absorption sites, and salt reflux and therefore result in low evaporation efficiency, poor salt tolerance, and terrible operational stability. Herein, we report poly(vinyl alcohol)/carbon nanotubes-co-poly(acrylic acid)-co-poly dimethyl diallyl ammonium chloride (PVA/CNTs-co-PAA-co-PDADMAC) (PADM) polyelectrolyte hydrogels via chemical cross-linking and polymerizing strategy. The as-prepared polyelectrolyte hydrogels possess interconnected porous channels (abundant porosity of 76.24%, high total pore area of 0.99 m² g^–1, large average pore diameter of 18.79 μm) and controllable cross-linking degree (good mechanical property), which can greatly promote the water mass transportation (0.395 g min^–1), light absorption sites, and salt reflux. As a result, the PADM polyelectrolyte hydrogels can maintain high evaporation rate of 3.58 kg m^–2 h^–1, excellent salt tolerance (evaporation rate of 3.18 kg m^–2 h^–1 under 20 wt % high-concentration brine), and superior operational stability (invariable evaporation rate after 8 days of continuous evaporation), which exhibits great advantage in solar-driven interfacial evaporation.

中文翻译：

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多孔和耐盐的聚电解质水凝胶，可实现出色的太阳能蒸发


具有低蒸发焓和高水分子活化能力的水凝胶被认为是太阳能驱动界面蒸发的有前途的衬底材料。然而，传统水凝胶不可控的多孔通道和交联度限制了水的大量传输、光吸收位点和盐回流，从而导致蒸发效率低、耐盐性差和糟糕的操作稳定性。在本文中，我们报道了通过化学交联和聚合策略制备的聚（乙烯醇）/碳纳米管-共聚（丙烯酸）-共聚二甲基二烯丙基氯化铵 （PVA/CNTs-co-PAA-co-PDADMAC） （PADM） 聚电解质水凝胶。所制备的聚电解质水凝胶具有互连的多孔通道（孔隙率高达 76.24%，总孔径高达 0.99 m² g^–1，平均孔径为 18.79 μm）和可控的交联度（良好的机械性能），可以极大地促进水的质量传递（0.395 g min^–1）、光吸收部位和盐反流。因此，PADM 聚电解质水凝胶可以保持 3.58 kg m^–2 h^–1 的高蒸发速率、优异的耐盐性（在 20 wt % 的高浓度盐水下蒸发速率为 3.18 kg m^–2 h^–1）和卓越的操作稳定性（连续蒸发 8 天后蒸发速率不变），这在太阳能驱动的界面蒸发中表现出很大的优势。