Adjusting Channel Size within PVA-Based Hydrogels via Ice Templating for Enhanced Solar Steam Generation
Adjusting Channel Size within PVA-Based Hydrogels via Ice Templating for Enhanced Solar Steam Generation
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DOI：
10.1021/acsaem.0c01584
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发表时间：
2020-09-28
影响因子：
6.4
通讯作者：
Kim, Franklin
中科院分区：
文献类型：
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作者：
Li, Chuang;Fan, Li;Kim, Franklin
近年来，太阳能蒸汽发电作为一种清洁的发电和水处理来源引起了人们的兴趣。为了获得高的水蒸气产生率，太阳能蒸发器不仅要有高的光热转换效率，而且要有较大的蒸发有效表面积。在这里，我们报告了使用基于PVA的复合水凝胶作为太阳能蒸发器，它的内部通道尺寸通过冰模板法进行调整。尽管PVA水凝胶作为一种很有前途的太阳能蒸汽发电材料已经得到了积极的研究，但内通道尺寸对材料性能的影响还没有得到很好的研究。到目前为止，大多数报道的PVA太阳能蒸发器的内通道尺寸都在几微米到几十微米的范围内。在这项研究中，我们通过在冻结水凝胶的同时抑制冰晶的生长，将通道尺寸缩小到亚微米范围。强大的毛细管力，可远距离输送水分。因此，即使将水凝胶模制成几厘米长的柱状结构，水也可以从一端快速输送到另一端，与通道尺寸更大的水凝胶相比，允许在更高的高度进行有效蒸发。蒸发水表面积的增加导致蒸发器在1个日照(100 mW cm(-2))下的单位水表面积的水蒸气产生率为6.35 kg m(-2)h(-1)，显著高于以前报道的数值。
Solar steam generation has attracted interest in recent years as a clean source for power generation and water treatment. To achieve a high rate of steam generation, it is important for the solar evaporator to not only have high photothermal conversion efficiency but also have a large effective surface area for water evaporation. Herein, we report the use of PVA-based composite hydrogels as the solar evaporator, which inner channel sizes were adjusted through an ice-templating method. Although PVA hydrogels have been actively pursued as a promising material for solar steam generation, the influence of inner channel sizes to material performance has not yet been well investigated. Up to this point, the inner channel sizes of most reported PVA-based solar evaporators have been in the range of several to a few tens of micrometers. In this study, we have narrowed the channel size down to submicrometer range by suppressing growth of ice crystals while freezing the hydrogels. Strong capillary force transport of water over long distances. Therefore, even when the hydrogel was molded into a pillar structure with length of several centimeters, water could be rapidly transported from one end to another, allowing effective evaporation at much increased heights compared to hydrogels with larger channel sizes. The increase in surface area for water evaporation led to a steam generation rate of 6.35 kg m(-2) h(-1) per water surface area covered by the evaporator under 1 sun illumination (100 mW cm(-2)), which is significantly higher than previously reported values.