| Nowadays,the conflict between population growth and freshwater shortage has become one of the most challenging issues in the twenty-first century.Fortunately,the earth is rich in seawater,from which pure drinking water can be obtained through the use of electrodialysis and distillation.However,these technologies have obvious disadvantages,such as high-energy consumption and environmental pollution.In recent years,solar-driven interfacial evaporation technology has attracted widespread attention from academia and industry.It has become a promising technique to produce freshwater owing to its eco-friendly,low-cost,safe,and electricity-independent purification of seawater,promisingly alleviating the freshwater crisis.With the advantages of large specific surface area,high strength,flexible structure regulation and mature industrialization,textile materials have become one of the ideal photothermal conversion substrate materials for evaporators.Therefore,in this paper,special structure of textile fabrics were designed to improve the effective evaporation area and photothermal utilization,including honeycomb structure fabric with concave honeycomb shape and three-dimensional fabric with vertical yarn arrangement,and then combined with the new photothermal conversion material-transition metal carbon/nitride（MXene）.The evaporation performance and desalination application of evaporator are studied as follows:（1）In order to improve the effective evaporation surface area of the current two-dimensional planar（2D）evaporator,a three-dimensional（3D）honeycomb fabric with millimeter-scale honeycomb pore structure was designed by adopting the advantage of easy tuning of the textile structure,and the MXene modified 3D honeycomb fabric evaporator was prepared by electrostatically assembling the photothermal conversion material of MXene.3D honeycomb structure fabric has periodic concave array structure,rough surface and high porosity characteristics,which promote multiple scattering and omnidirectional light collection absorption of internal light.Minimal heat loss can be achieved by creating localized photothermal localization through a thermally insulated support layer connected with a closed one-dimensional water transport path and a concave structure,which can effectively recovers dissipative convective and radiant heat losses.By constructing a closed one-dimensional water path in the center of the evaporator,the salt solution transport in the evaporator creates a radial concentration gradient from the center to the edge,where the salt crystallizes at the edge even if the brine concentration is as high as 21%,thus achieving complete water/solute separation and efficient salt harvesting.The evaporator demonstrates high solar efficiency of up to93.5%and evaporation rate of 1.62 kg m-2 h-1 under one sun irradiation.（2）To further improve the evaporation rate of the evaporator,a vertical yarn array is used to construct a 3D fabric evaporator with a certain height,which achieves the integration of high evaporation rate,anti-pollution,and recyclable evaporation enthalpy.we have innovatively developed a 3D evaporator with multiscale pores（macroporous and microporous）using MXene and polydopamine（PDA）/polyethyleneimine（PEI）-decorated vertical hemp-fiber arrays.The unique multiscale pores of the 3D vertical array evaporator enable maximum light capturing,while the rich pores significantly increase the evaporation area and vapor escape space.The side temperature of the 3D evaporator is lower than the ambient temperature,which gains additional energy from the ambient environment to achieve full dimensional water evaporation.The developed3D evaporator achieves an evaporation rate of up to 3.95 kg m-2 h-1 under 1 sun illumination and outdoor evaporation of 47.04 kg m-2 for continuous 8 h.The antimicrobial properties of hemp fiber and MXene make the evaporator prominent microbial resistance（antibacterial efficiency above 99.9%）,the excellent hydrophilicity of PDA/PEI makes the evaporator have desirable anti-oilfouling performance,and the circulation and flow of brine in the multiscale pores of the evaporator makes it have excellent salt-resistance（continuous 120 h in 14%brine without salt crystals）for long-term stability in seawater desalination.Furthermore,an integrated"desalination–thermoelectricity–irrigation"evaporation system is innovatively built,where the desalinated water can be used for real-time and on-demand crop growth through the irrigation cultivation platform,and the recovered steam enthalpy can generate electricity and preheat seawater,broadening the application of desalination evaporators in different fields. |
