静电纺纳米纤维在界面太阳能蒸汽转化应用中的研究进展

Research progress in electrospun nanofibers in interfacial solar steam generation

静电纺纳米纤维因其具有高比表面积、孔隙结构可控等优点而被用作界面太阳能蒸汽发生器基底,然而由于其力学性能不足、与光热材料的结合力差等限制了其长足发展。为此,介绍了静电纺纳米纤维的特点及其与光热材料结合的主要方式,包括表面修饰、共混纺丝、Janus纳米纤维膜以及三维纳米纤维气凝胶,对其原理、性能和工艺方法等进行系统性概述;并在此基础上展望了该研究领域的未来发展趋势,以探索静电纺纳米纤维在光热能源领域中广泛应用的方法。研究认为,加强静电纺纳米纤维与光热材料结合力并赋予其抗菌、自清洁等多功能性,是提高太阳能蒸汽发生器持久使用的一大方法,探寻简易的制备方法和开发低成本材料高性能太阳能蒸汽发生器是未来的发展重点。

Significance Solar steam generation is a method to generate steam from solar energy to obtain clean water resources which can convert solar energy into heat energy and solve the problem of clean water shortage with minimal environmental impact.Electrospun nanofibers have been used as the substrate of interfacial solar steam generator by means of its structural features.Electrospinning can provide nanofibers with high specific surface area to enhance the evaporation process,continuous fibers can transport water over long distances,which can ensure adequate water supply,and the porosity and pore structure of the film can be adjusted to achieve higher vapor diffusion by adjusting the parameters of the electrostatic spinning device.Moreover,many reports confirmed that the electrospun nanofiber-based evaporator can achieve seawater desalination,wastewater purification and other purposes by using interfacial solar steam generation.Progress In this paper,four main ways of combining electrospun nanofibers with photothermal materials in two-dimensional nanofiber membrane and three-dimensional nanofiber aerogel evaporator were introduced,with their principles,properties and process methods systematically summarized.The performance of different types of solar evaporators using electrospun nanofiber-based was compared and discussed.It is showed that these evaporators can achieve a maximum evaporation rate of 3.81 kg/(m 2•h)with a conversion efficiency of 90.1%and salt resistance of 99%under one sun irradiation.The conventional methods of two-dimensional surface modified electrospun nanofiber membrane,the principles of two-dimensional blending electrospun nanofiber membrane,two-dimensional Janus electrospun nanofiber membrane and three-dimensional electrospun nanofiber aerogel were scutinized.The surface modification of electrospun nanofiber membrane leads to many functional materials,such as loading conductive materials for sensors,spraying antibacterial agents for antibacterial properties,depositing photothermal materials to make solar steam generators.Surface modification is mainly divided into physical methods and chemical methods.Electrospun nanofiber membrane is prepared by mixing polymer and photothermal materials into uniform spinning solution through electrospinning.The preparation of Janus electrospun nanofiber membranes is generally carried out by surface modification on the upper and lower sides of the nanofiber membranes or by step spinning on different spinning fluids,so as to achieve the effect of different characteristics on both sides of the nanofiber membranes.Electrospun nanofiber-based aerogel is prepared by freeze-drying of nanofibers,photothermal materials and crosslinking agents in the nanofiber membrane.The three-dimensional aerogel prepared by nanofiber offers larger volume and higher specific surface area,which not only can improve the binding strength between nano-fiber and photothermal materials,but also fully improve the evaporation rate and salt resistance of solar evaporator.Conclusions and Prospect The electrospun nanofiber-based solar steam generator makes use of the characteristics of electrospun nanofibers,enriches the combination of nanofibers and photothermal materials,and effectively expands the application of nanofibers in the field of photothermal energy.However,there are still some challenges,such as low strength,poor adhesion with photothermal materials and insufficient function,which limit the development of electrospun nanofibers in the application of solar steam generation.Practical application process of solar steam generator often faces issues such as complex water environment(such as seawater,acid and alkali wastewater)where strengthened adhesion between electrospun nanofibers and photothermal materials is necessary to impart multi-functions such as bacterial resisting and self-cleaning.The thickness of two-dimensional planar solar evaporator directly constructed by electrospun nanofiber membrane is small which makes the thermal management,and hence water supply and vapor diffusion in the process of water evaporation cannot be carried out faster.In order to solve this problem,solar steam generators need to focus on constructing two-dimensional nanofiber membranes into three-dimensional structures,optimize the structure design,and make full use of solar energy to improve the ability of photothermal steam conversion.In addition,photothermal materials and nanofibers still have problems such as high production cost and long technological process at present.It is believed that developing simple preparation methods and low-cost materials for high-performance solar steam generators represent a key perspective in future development.