【Frontiers in HaiChuan Chemical Technology】A research team from Donghua University develops biomimetic photothermal fabrics to aid in solar-driven seawater desalination

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Bionic photothermal fabrics aid in solar seawater desalination March 24, 2025 Report Solar seawater desalination technology is regarded as the \"best solution\" for addressing the freshwater crisis. Recently, the research team led by Chen Zhigang from Donghua University developed, through biomimetic design, a breathable photothermal fabric evaporator with a three-layer structure. This evaporator not only enables efficient evaporation from all four sides but also overcomes the bottleneck associated with salt crystallization, thus accelerating the industrial application of seawater desalination. The relevant research findings were published in Advanced Materials. 　　How can plant leaves achieve efficient transpiration through their thin outer layer? The answer lies in their sophisticated three-layer structure: the epidermis retains water, the middle layer transports water, and the stomata facilitate evaporation. The research team replicated this natural wisdom in artificial materials; using individual fibers of commercial polyester (PET) as raw material, they developed a breathable two-dimensional three-layer structured photothermal fabric through weaving and laser engraving techniques. According to Hu Jinjing, a member of Chen Zhigang’s research team, they used carbon/polymer hydrogels to modify the surface of the fabric, and employed lasers to carve arrays of pores into the top layer of the fabric, thereby creating photothermal fabrics with a structure similar to that of leaves. This fabric features an upper layer, a lower layer, and an air layer created by short fiber columns between them, forming an innovative three-layer structure while retaining the flexibility and scalability of two-dimensional materials. 　　Experimental tests have shown that this fabric possesses broad-spectrum and a high solar absorption efficiency of 96.1%, enabling it to almost \"extract every bit of sunlight\". The air-filled pores and intermediate layer effectively reduce heat loss during the evaporation process, resulting in superior photothermal conversion performance and providing an ideal photothermal platform for efficient solar seawater evaporation. Furthermore, the fabric surface contains a large number of polar functional groups, which can regulate the state of surface water molecules through strong hydrogen bonds and electrostatic interactions, significantly reducing the energy required for water molecules to \"escape\". This in turn lowers the enthalpy of evaporation and improves the evaporation efficiency. 　　The solar-gradient evaporator constructed with this fabric functions like an \"artificial leaf\"; seawater flows between the upper and lower fabric layers, enabling the transfer of seawater from the higher seawater tank to the lower one. Under sunlight, the fabric absorbs solar energy and converts it into heat, causing the seawater to evaporate simultaneously on the upper and lower surfaces of the top layer of fabric as well as on the upper and lower surfaces of the bottom layer of fabric. The concentrated seawater remaining after evaporation drips from the bottom of the fabric into a collection tank placed at a lower level, thereby completely avoiding the problem of salt accumulation on the evaporation surface. Hu Jinjing used an analogy: “Traditional 2D membranes are like single-sided pans, while we have created intelligent steamers that can enable ‘evaporation from all four sides’.” ”Studies show that its evaporation rate is 1.6 times that of conventional 2D membranes. 　　This fabric also offers significant cost advantages, as its raw material, polyester fiber, costs only 1/3 of that of hydrogels, and its weaving process is compatible with the textile industry. Chen Zhigang pointed out: “3D hydrogel evaporators are like custom-made suits, while our materials are fabric that can be cut in bulk.” ”Ongoing follow-up studies show that vertically inclined evaporators can prevent the formation of salt crystals on the evaporation surface during continuous thousand-hour tests. This design of halite droplets falling from the bottom of the evaporator functions like an “automatic salt discharge valve,” addressing a long-standing problem in this industry. 　　This research finding opens up new perspectives for the large-scale design of 2D flexible photothermal membranes and the industrial application of solar-driven seawater desalination, providing innovative solutions to the global freshwater crisis.