Cui Tongtong, Liu Zhen, Gao Lingling, He Yisheng, Jin Bowen, Meng Xiao, Qi Yanpeng, Ye Chunhong
School of Physical Science and Technology, ShanghaiTech University, Shanghai201210, China.
ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai201210, China.
Langmuir. 2022 Oct 25;38(42):12773-12784. doi: 10.1021/acs.langmuir.2c01162. Epub 2022 Oct 14.
Wood-based solar steam evaporators have been attracting increasing interest due to their great potential for addressing water scarcity by utilizing sustainable materials and energy. However, engineering a 3D porous structure within the wood lumens and its effect on solar vapor evaporation have not yet been well explored. Here, a natural wood-based solar evaporator with hierarchical pores is fabricated by assembling polyvinyl alcohol within the lumens through an ice-templating approach. The polyvinyl alcohol porous network is engineered from vertically aligned microchannels to dendritically bridged pores with a narrowed size of a few micrometers and significantly increased surface area. Although the formation of plenty of microscopic channels increases the capillary force in comparison to the native wood lumen, the morphology change induces a high tortuosity factor of the porous structure, resulting in a reduced water transportation rate as well as an increased contact angle. On the other hand, the high surface area of the engineered wood lumens and the good hydrophilicity of the filled polyvinyl alcohol improve the ratio of the formed intermediate water, contributing to reduced vaporization enthalpy. Consequently, by using polydopamine as the photothermal material, the hierarchically structured polyvinyl alcohol-wood solar evaporator exhibits an evaporation rate of 1.6 kg m h under 1 sun irradiation and a high solar evaporation efficiency of up to 107%, which are higher than most of the reported natural-wood-based solar evaporators. Moreover, by exploring the correlation between porous morphology and performance, it has been found that the polyvinyl alcohol-wood composite not only presents an inexpensive and sustainable evaporator but also provides guidelines for designing high-performance steam generation devices.
木质太阳能蒸汽蒸发器因其利用可持续材料和能源解决水资源短缺问题的巨大潜力而受到越来越多的关注。然而，在木材管腔内构建三维多孔结构及其对太阳能蒸汽蒸发的影响尚未得到充分研究。在此，通过冰模板法在管腔内组装聚乙烯醇，制备了一种具有分级孔隙的天然木质太阳能蒸发器。聚乙烯醇多孔网络由垂直排列的微通道构建而成，形成树枝状桥接孔隙，孔径缩小至几微米，表面积显著增加。尽管与天然木材管腔相比，大量微观通道的形成增加了毛细力，但形态变化导致多孔结构的曲折因子较高，从而降低了水的传输速率并增大了接触角。另一方面，工程化木材管腔的高表面积和填充的聚乙烯醇的良好亲水性提高了中间水的形成比例，有助于降低汽化焓。因此，通过使用聚多巴胺作为光热材料，这种具有分级结构的聚乙烯醇-木材太阳能蒸发器在1个太阳辐射强度下的蒸发速率为1.6 kg m² h，太阳能蒸发效率高达107%，高于大多数已报道的天然木质太阳能蒸发器。此外，通过探索多孔形态与性能之间的相关性，发现聚乙烯醇-木材复合材料不仅提供了一种廉价且可持续的蒸发器，还为设计高性能蒸汽发生装置提供了指导。
