Photo-thermal conversion coating and method for preparing same, photo-thermal conversion device

Abstract

The application belongs to the technical field of photothermal conversion materials, and particularly relates to a photothermal conversion coating, a preparation method thereof and a photothermal conversion device. The preparation method of the photothermal conversion coating comprises the following steps: obtaining a porous substrate, adsorbing an initiator in the porous substrate in situ to obtain a modified porous substrate, and performing a gas phase polymerization reaction on the modified porous substrate with a conjugated polymer monomer and a chlorine source to form a chlorine-doped photothermal conversion coating on the surface of the porous substrate in situ. In the preparation method of the photothermal conversion coating, the initiator is adsorbed in the porous substrate in situ, and the conjugated polymer monomer is diffused in the form of gas on the surface layer of the substrate, so that the monomer is polymerized in the pores of the substrate in situ, and the combination firmness of the coating and the substrate is improved. Meanwhile, the structuralization and doping effects improve the utilization rate of the coating to light energy, so that the photothermal conversion coating has the characteristics of high solar spectrum absorption efficiency, wide light absorption range, high absorption degree and high utilization rate, and exhibits super strong photothermal effect.

Description

Technical Field

[0001] This application belongs to the field of photothermal conversion materials technology, and particularly relates to a photothermal conversion coating and its preparation method, as well as a photothermal conversion device. Background Technology

[0002] With industrialization and global environmental changes, increasing pollution and a growing global population have led to a continuous rise in freshwater demand, making water pollution one of the world's largest crises. Seawater accounts for 97.5% of the Earth's water volume, while domestic wastewater and industrial wastewater also constitute a significant portion. Improving the supply and demand of seawater and wastewater will be crucial to addressing the shortage of usable water resources. Over the past few decades, researchers have developed numerous desalination and water treatment technologies, such as reverse osmosis and thermal distillation. However, these technologies' over-reliance on fossil fuels results in substantial energy consumption and secondary pollutants, causing severe environmental consequences.

[0003] Solar energy, as a green and environmentally friendly sustainable energy source, provides endless power for the survival of organisms and the cycle of matter in nature. Inspired by the natural atmosphere-water cycle, solar-driven interfacial evaporation technology, which uses photothermal conversion materials to convert solar energy into heat energy and then uses it to convert liquid water into water vapor, is called solar water evaporation technology. It features environmental protection, energy saving, and high separation efficiency, and has shown great potential in seawater desalination, wastewater purification, sterilization, and combined hydropower, which also greatly aligns with the concept of sustainable development in human society.

[0004] The photothermal conversion layer is a core component of interfacial solar water evaporation systems. For this layer, a series of materials with photothermal conversion properties have been developed, such as amorphous carbon, carbon nanotubes, metal nanoparticles, and organic polymers. Among these materials, conjugated polymers are rationally considered lightweight and efficient due to their excellent photothermal conversion performance, low thermal conductivity, and high optical stability. However, conjugated polymer-based photothermal conversion materials lack effective solar light capture methods, which is the main reason for their low solar spectrum utilization and directly limits their photothermal energy conversion efficiency. Furthermore, the difference in elastic modulus between the polymer and the substrate may lead to low bonding strength. Therefore, developing a highly efficient, stable, and universally applicable photothermal conversion polymer coating is a necessary challenge. Summary of the Invention

[0005] The purpose of this application is to provide a photothermal conversion coating and its preparation method, as well as a photothermal conversion device, which aims to solve to some extent the problems of existing photothermal conversion materials lacking effective means of capturing sunlight and having poor bonding stability with the substrate.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0007] In a first aspect, this application provides a method for preparing a photothermal conversion coating, comprising the steps of:

[0008] A porous substrate is obtained, and an initiator is adsorbed in situ into the porous substrate to obtain a modified porous substrate.

[0009] A gas-phase polymerization reaction is carried out between the conjugated polymer monomer and the chlorine source and the modified porous substrate to form a chlorine-doped photothermal conversion coating in situ on the surface of the porous substrate.

[0010] Secondly, this application provides the above-mentioned photothermal conversion coating, which is attached to the surface of a substrate and includes a chlorine-doped conjugated polymer.

[0011] Thirdly, this application provides a photothermal conversion device, wherein the functional layer of the photothermal conversion device includes the aforementioned photothermal conversion coating.

[0012] The method for preparing the photothermal conversion coating disclosed in this application involves, on the one hand, the initiator being adsorbed in situ into a porous substrate, while the conjugated polymer monomers are diffused in gaseous form onto the substrate surface. This initiates in-situ polymerization of the conjugated polymer monomers within the pores of the substrate surface, causing the coating to adhere firmly to the substrate surface, similar to a climbing vine. This not only significantly improves the bonding strength between the photothermal conversion coating and the substrate, enhancing the coating's weather resistance, environmental stability, and extending its service life, but also improves the adaptability of the photothermal conversion coating to various substrates of any shape, type, and size, allowing it to grow and form a stable photothermal conversion coating, thus increasing the coating's application flexibility. Furthermore, the coating generates a wrinkled structure during the gas-phase polymerization process. This structuring effect enables multiple reflections and absorptions of incident light within the coating's microstructure, thereby improving the coating's light energy utilization rate. On the other hand, the photothermal conversion coating is uniformly doped with chloride ions in situ. The doping of chloride ions in some main chain structures causes the conjugated polymer to be in different states such as neutral, polarized, and bipolarized, which can greatly broaden the utilization rate of the solar spectrum of the conjugated polymer. This makes the chloride-doped photothermal conversion coating have the characteristics of wide light absorption range and high absorption, thereby improving the photothermal conversion efficiency of the photothermal conversion coating.

[0013] The photothermal conversion coating provided in the second aspect of this application, prepared by the aforementioned method, grows in situ on the surface of a substrate. The coating adheres firmly to the substrate surface, much like a climbing vine, greatly improving the bonding strength between the coating and the substrate, enhancing its weather resistance, and enabling it to withstand long-term water flow impact (72h, 1800r / min), freeze-thaw cycles, and acid / alkali corrosion environments. Its good environmental stability ensures a long cycle life during use. Furthermore, the photothermal conversion coating can grow on substrates of any shape, type, and size, increasing its application flexibility. The photothermal conversion coating grown in situ using the aforementioned method exhibits a wrinkled structural effect, enhancing the multiple reflections and absorption of incident light within the microstructure, thus improving light energy utilization. Additionally, the conjugated polymer in the photothermal conversion coating is doped with chloride ions, and through structuring and doping effects, the coating exhibits a superior photothermal effect.

[0014] The photothermal conversion device provided in the third aspect of this application has a higher photothermal conversion efficiency because its functional layer includes the aforementioned photothermal conversion coating. This photothermal conversion coating has characteristics such as high absorption efficiency of the solar spectrum, wide light absorption range, high absorptivity, and high utilization rate. Therefore, the photothermal conversion efficiency of the photothermal conversion device is improved. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic flowchart of the method for preparing the photothermal conversion coating provided in the embodiments of this application;

[0017] Figure 2 This is a schematic diagram of the structure of the solar water evaporator device provided in the embodiments of this application;

[0018] Figure 3 These are physical images and scanning electron microscope images of the photoelectric conversion coatings grown on different substrates in Examples 1 to 6 of this application;

[0019] Figure 4 The images show the X-ray diffraction pattern (a), Raman spectrum (b), and FTIR spectrum (c) of the Cl-PEDOT coating grown in situ on the wood surface in Example 1 of this application.

[0020] Figure 5The following are the temperature-time curves of the Cl-PEDOT coating surface prepared in Example 2 of this application (a), the temperature-time curve during photothermal de-icing (b), and the temperature-time curve under outdoor sunlight (c).

[0021] Figure 6 The figures shown are: (a) the enthalpy of evaporation test results of water in the photoelectric conversion coatings of Examples 1 to 6 of this application; (b) the water mass loss test result of the photoelectric conversion coating surface; and (c) the test result of water evaporation rate and light-to-vapor conversion linearity.

[0022] Figure 7 This is a schematic diagram (a) of the process of making a solar water evaporation-condensation device with a photothermal heat exchange coating according to Embodiment 1 of this application, and a diagram (b) showing the solar water evaporation data and the change in outdoor light intensity. Detailed Implementation

[0023] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0024] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0025] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0026] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0027] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms "a" and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0028] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass in the embodiments of this application can be a well-known unit of mass in the chemical industry, such as μg, mg, g, or kg.

[0029] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0030] As attached Figure 1 As shown, the first aspect of this application provides a method for preparing a photothermal conversion coating, including the following steps:

[0031] S10. Obtain a porous substrate, and adsorb the initiator in situ into the porous substrate to obtain a modified porous substrate;

[0032] S20. A gas-phase polymerization reaction is carried out between the conjugated polymer monomer and the chlorine source and the modified porous substrate to form a chlorine-doped photothermal conversion coating in situ on the surface of the porous substrate.

[0033] The method for preparing a photothermal conversion coating provided in the first aspect of this application involves firstly, in-situ adsorption of an initiator into a porous substrate, allowing the initiator to be pre-embedded within the porous pores of the substrate surface. Then, a conjugated polymer monomer and a chlorine source are subjected to a gas-phase polymerization reaction with the modified porous substrate. The conjugated polymer monomer and chlorine source react with the porous substrate in a gaseous state, and the initiator pre-adsorbed in the modified porous substrate initiates the redox polymerization of the monomer on the substrate surface, forming a dense and complete photothermal conversion coating of uniform thickness in situ on the substrate surface. Simultaneously, the chlorine source forms a uniform and stable dopant in the photothermal conversion coating. In this method, the initiator is in-situ adsorbed into the porous substrate, and the conjugated polymer monomer escapes in a gaseous state onto the substrate surface, initiating in-situ polymerization of the conjugated polymer monomer in the pores of the substrate surface. This allows the coating to adhere firmly to the substrate surface, similar to a climbing vine. This significantly improves the bonding strength between the photothermal conversion coating and the substrate, enhances the coating's weather resistance and environmental stability, and extends its service life. Simultaneously, it improves the adaptability of the photothermal conversion coating to substrates, allowing it to adhere to and grow on substrates of any shape, type, and size to form a stable photothermal conversion coating, thus enhancing the application flexibility of the coating. Furthermore, the coating generates a wrinkled structure during the gas-phase polymerization process. This structuring effect enables multiple reflections and absorptions of incident light within the coating's microstructure, thereby improving the coating's light energy utilization rate. On the other hand, the photothermal conversion coating is uniformly doped with chloride ions in situ. Chloride ion doping in some main chain structures leads to the conjugated polymer exhibiting different states such as neutral, polarized, and bipolarized states, which can greatly broaden the utilization rate of the solar spectrum by the conjugated polymer. This results in the chloride-doped photothermal conversion coating possessing characteristics such as a wide light absorption range and high absorbance, thereby improving the photothermal conversion efficiency of the coating.

[0034] In some embodiments, step S10 above, the step of in-situ adsorption of the initiator in the porous substrate, includes: immersing the porous substrate in a solution of the initiator to allow the initiator to be fully adsorbed into the pores of the porous substrate, especially the surface pores, and then drying to allow the solvent to evaporate and be removed, so that the initiator is in-situ adsorbed into the pores of the porous substrate, thereby obtaining a modified porous substrate.

[0035] In some embodiments, the solvent in the initiator solution includes, but is not limited to, alcohol solvents such as ethanol and methanol. These solvents have good solubility for the initiator, low boiling points, and are easily removed by heating and evaporation.

[0036] The embodiments of this application demonstrate a method for preparing a chlorine-doped photothermal conversion coating on the surface of a modified porous substrate by pre-adsorbing an initiator in situ into the pores of a porous substrate, and then polymerizing the conjugated polymer monomer and chlorine source in the gas phase. This method is applicable to substrates of any shape, material, and size.

[0037] In some embodiments, the porous substrate is selected from at least one of wood, rock wool, ceramic mesh, filter paper, fabric, and cotton.

[0038] In some embodiments, the initiator is selected from at least one of ferric salts and copper salts. Both ferric and copper ions in these initiators can initiate the polymerization of conjugated polymer monomers to form a conjugated polymer. In some embodiments, the ferric salt includes, but is not limited to, ferric chloride and ferric sulfate. The copper salt includes, but is not limited to, copper chloride and copper sulfate. In some preferred embodiments, the initiator is a ferric salt, as ferric ions can better initiate the polymerization of conjugated polymer monomers to form a conjugated polymer.

[0039] In some embodiments, the initiator is selected from chloride salts. In some specific embodiments, the initiator is selected from at least one of ferric chloride and copper chloride. The anion in the initiator is a chloride ion, which is pre-adsorbed into the pores of the substrate by the initiator, which is beneficial for the uniform and stable doping of the chloride source into the photothermal conversion coating and improves the chloride source doping efficiency.

[0040] In some embodiments, the initiator solution concentration is 0.05–0.5 mol / mL. In this case, immersing the porous substrate with this concentration of initiator is more conducive to the in-situ and uniform adsorption of the initiator into the pores of the porous substrate. If the initiator solution concentration is too high or too low, it is not conducive to the uniform adsorption of the initiator in the porous substrate and the in-situ initiation of interfacial redox polymerization.

[0041] In some embodiments, step S20 above, the step of gas-phase polymerization of the conjugated polymer monomer and chlorine source with the modified porous substrate, includes: mixing the conjugated polymer monomer and chlorine source with the modified porous substrate in a gaseous form, i.e., the conjugated polymer monomer and chlorine source diffuse in gaseous form onto the surface of the modified porous substrate; through the initiation effect of the initiator adsorbed in situ in the pores of the substrate surface, the conjugated polymer monomer polymerizes in situ on the surface of the porous substrate, while chlorine ions are in situ doped; the chlorine-doped photothermal conversion coating adheres firmly and densely to the surface of the porous substrate, similar to a climbing vine. This not only improves the uniformity, density, and bonding strength of the chlorine-doped photothermal conversion coating with the substrate; but also has high adaptability to substrates, adaptable to growth on substrate surfaces of any shape, type, and size, making it flexible and convenient to apply. In addition, the gas-phase polymerization process avoids the ineffective consumption of monomers inside the substrate.

[0042] In some embodiments, the conjugated polymer monomers are selected from at least one of pyrrole and 3,4-ethylenedioxythiophene. These monomers can be polymerized into conjugated polymers such as polypyrrole and polythiophene by initiation with an initiator. These conjugated polymers have excellent photothermal conversion properties, low thermal conductivity, and high optical stability, making them rational lightweight and efficient photothermal conversion materials. The conjugated polymers prepared by the in-situ gas-phase oxidative polymerization method in the embodiments of this application have better crystallinity and a unique structure, which can further optimize the photothermal properties of the conjugated polymers, thereby improving the photothermal absorption and conversion efficiency of the coating.

[0043] In some embodiments, the molar ratio of initiator, chlorine source, and conjugated polymer monomer is 1:(3-5):(1000-10000). In this case, the initiator can effectively initiate the in-situ polymerization of the conjugated polymer monomer on the surface of the porous substrate to form a photothermal conversion coating. Simultaneously, the doping concentration of chloride ions in the photothermal conversion coating is beneficial for improving the photothermal properties of the conjugated polymer.

[0044] In some embodiments, a chlorine source can be added to the reaction system in the form of chlorine gas to carry out a gas-phase polymerization reaction, forming a chlorine-doped photothermal conversion coating in situ on the surface of the porous substrate. In other embodiments, the chlorine source can also be added in anionic form, specifically including but not limited to chloride ions as initiators. The initiator is directly pre-attached to the pores of the porous substrate. During the gas-phase polymerization reaction, the initiator decomposes into metal ions and chloride ions at high temperature. The metal anions initiate the in-situ polymerization of conjugated polymer monomers on the surface of the porous substrate. At the same time, free chloride ions are in-situ doped into the conjugated polymer coating, forming a chlorine-doped photothermal conversion coating in situ on the surface of the porous substrate.

[0045] The vapor-phase polymerization method described in this application can effectively transform substrates of various shapes into photothermal conversion materials coated with a photothermal conversion coating, which is highly beneficial for the development of evaporator structures. In some embodiments, the substrate is configured into a multi-conical structure, and the prepared chlorine-doped photothermal conversion coating is tightly bonded to the surface of the macroscopic conical structure substrate. This conical structure, through continuous reflection and refraction of light, further enhances the coating's absorption and utilization efficiency of sunlight, thereby improving the coating's photothermal conversion efficiency.

[0046] In some specific embodiments, the preparation of the photothermal conversion coating includes the following steps:

[0047] S10. The initiator is selected from ferric chloride. The porous substrate is immersed in a ferric chloride solution and dried to obtain a modified porous substrate adsorbed with ferric chloride initiator.

[0048] S20. The solution of the conjugated polymer monomer and the modified porous substrate are placed in the same reaction system, and the conjugated polymer monomer is heated to vaporize and diffuse onto the surface of the modified porous substrate. The in-situ polymerization reaction is carried out for 2 to 4 hours under the initiation of the initiator, and a chlorine-doped photothermal conversion coating is formed on the surface of the porous substrate.

[0049] In some specific embodiments, the heating temperature includes, but is not limited to, 120–200°C. Under this temperature condition, it is not only beneficial for the conjugated polymer monomers to vaporize into a gas phase, and the gas phase monomers have high free activity; but also under this temperature condition, the initiator has high activity, which is beneficial for initiating the in-situ polymerization of the conjugated polymer monomers that have escaped to the surface of the modified porous substrate to form a conjugated polymer coating on the substrate surface.

[0050] In some specific embodiments, a chlorine-doped Cl-PEDOT coating is tightly bonded to a macroscopically conical wood substrate, forming a conical wood solar evaporator. This device can achieve a water evaporation rate of 2.1 kg·m³. -2 ˙h -1 The energy utilization efficiency can reach 91%. Furthermore, under low light (0.5 Sun), the Cl-PEDOT coated conical wood evaporator exhibited an energy efficiency of 1.19 kg·m³. -2 ˙h -1 The water evaporation rate set a new evaporation record for wood-based evaporators in low-light environments.

[0051] A second aspect of this application provides the above-described photothermal conversion coating, which is grown in situ on the surface of a substrate and includes a chlorine-doped conjugated polymer.

[0052] The photothermal conversion coating provided in the second aspect of this application is prepared by the above-described method. This coating grows in situ on the surface of a substrate, adhering firmly to the substrate surface like a climbing vine, greatly improving the bonding strength between the coating and the substrate and enhancing its weather resistance. It can withstand long-term water flow impact (72h, 1800r / min), freeze-thaw cycles, and acid / alkali corrosion environments, exhibiting good environmental stability and ensuring a long cycle life during use. Furthermore, the photothermal conversion coating can grow on substrates of any shape, type, and size, improving its application flexibility. The photothermal conversion coating grown in situ by the above method has a wrinkled structural effect, enhancing the multiple reflections and absorption of incident light in the microstructure and improving light energy utilization. In addition, the conjugated polymer in the photothermal conversion coating is doped with chloride ions, and through the structural and doping effects, the coating exhibits a superior photothermal effect.

[0053] In some embodiments, the chloride ion doping mass percentage in the photothermal conversion coating is 0.01% to 0.005%. This doping concentration of chloride ions has a better optimization effect on the photothermal conversion efficiency of the conjugated polymer, broadens the utilization rate of the solar spectrum of the conjugated polymer, and makes the photothermal conversion coating have characteristics such as wide light absorption range and high absorption, thereby better improving the photothermal conversion efficiency of the photothermal conversion coating.

[0054] In some embodiments, the substrate includes at least one of wood, rock wool, ceramic mesh, filter paper, fabric, and cotton. The photothermal conversion coating of this application embodiment is prepared by the above-described method of pre-adsorbing an in-situ initiator into the pores of a porous substrate, and then polymerizing the conjugated polymer monomer and chlorine source in the gas phase to form a chlorine-doped photothermal conversion coating in situ on the surface of the modified porous substrate. This allows the photothermal conversion coating to bond tightly with substrates of any shape, material, and size, exhibiting good stability, improved weather resistance and environmental stability, and extended service life.

[0055] In some embodiments, the conjugated polymer includes at least one of polypyrrole, polyaniline, and polythiophene. These conjugated polymers possess excellent photothermal conversion properties, low thermal conductivity, and high optical stability, making them rational lightweight and efficient photothermal conversion materials. The conjugated polymers prepared by the in-situ gas-phase oxidative polymerization method described in the above embodiments have better crystallinity and a unique structure, which can further optimize the photothermal properties of the conjugated polymers, thereby improving the photothermal absorption and conversion efficiency of the coating.

[0056] In some embodiments, the chlorine-doped conjugated polymer is selected from chlorine-doped polythiophene. The chlorine-doped polythiophene in the photothermal conversion coating of this application has characteristics such as a wide light absorption range and high absorbance, which is beneficial for improving the photothermal conversion efficiency of the coating.

[0057] In some embodiments, the Cl-PEDOT photothermal conversion coating exhibits oil-resistant properties. The inert substrate, after being modified with the Cl-PEDOT coating, possesses superhydrophilic-superoleophobic properties underwater, significantly improving water molecule permeability and effectively preventing oily substances from contaminating the substrate.

[0058] In some embodiments, the chlorine-doped conjugated polymer is black. In the photothermal conversion coating prepared by the above method in this application embodiment, the chlorine-doped conjugated polymer, through structuring and doping effects, results in a black color. Darker conjugated polymers have better light absorption efficiency, which is beneficial for improving the light utilization rate of the coating, thereby improving the photothermal conversion efficiency of the photothermal conversion coating.

[0059] A third aspect of this application provides a photothermal conversion device, wherein the functional layer of the photothermal conversion device includes the aforementioned photothermal conversion coating.

[0060] The photothermal conversion device provided in the third aspect of this application has a higher photothermal conversion efficiency because its functional layer includes the aforementioned photothermal conversion coating. This photothermal conversion coating has characteristics such as high absorption efficiency of the solar spectrum, wide light absorption range, high absorptivity, and high utilization rate. Therefore, the photothermal conversion efficiency of the photothermal conversion device is improved.

[0061] In some specific embodiments, the photothermal conversion device is a solar water evaporator, the structure of which is shown in the attached figure. Figure 2 As shown, the entire device is a sealed glass dome. The upper surface of the dome is tilted at a 45° angle, the bottom is flat, and the other three sides are perpendicular to the bottom. A water-resistant glass is placed at the bottom one-fifth of the dome, dividing the bottom of the dome into two parts. The rear four-fifths of the area is used to store the raw brine, and the front one-fifth of the volume is used to collect the purified water. A porous substrate modified with a photothermal conversion coating serves as the photothermal conversion layer. A layer of hydrophilic gauze is laid on the lower surface, and below the gauze is a plastic foam insulation board (to facilitate water transfer, a through hole is drilled in the middle of the foam board, through which the gauze is directly immersed into the raw brine at the bottom). These three layers constitute the photothermal evaporation water working layer, which is suspended on the surface of the raw brine. A xenon lamp is used as the light source to simulate solar energy or direct sunlight irradiation of the water evaporation environment. The evaporation system is placed on an analytical electronic balance, and the water quality changes are recorded periodically using computer data recording software (METTLER TOLEDO SerialPortToKeyboard).

[0062] To enable those skilled in the art to clearly understand the above-described implementation details and operations of this application, and to demonstrate the significant advancements in the performance of the photothermal conversion coating, its preparation method, and its application in the embodiments of this application, the following examples illustrate the above technical solutions.

[0063] Example 1

[0064] A photothermal conversion coating, the preparation of which includes the following steps:

[0065] 1. Place clean, untreated wood in 100mL of ethanol solution containing 8.1g of FeCl3. After the wood surface is completely impregnated, remove it and dry it in an oven at 40℃ for 10min to obtain the modified substrate.

[0066] 2. Place the modified substrate from step 1 above and the ethanol solution containing 3 mL of 0.05 mM EDOT (3,4-ethylenedioxythiophene) separately in the same glass container. Then, place the sealed glass container in an oven and heat it to 150°C for 4 hours. After that, take out the substrate, wash it with water 3 times, and let it dry naturally. A Cl-PEDOT photothermal coating will grow in situ on the wood surface.

[0067] Example 2

[0068] A photothermal conversion coating, which differs from Example 1 in that the substrate is made of rock wool.

[0069] Example 3

[0070] A photothermal conversion coating, which differs from Example 1 in that the substrate is a ceramic mesh.

[0071] Example 4

[0072] A photothermal conversion coating, which differs from Example 1 in that the substrate is filter paper.

[0073] Example 5

[0074] A photothermal conversion coating, which differs from Example 1 in that the substrate is made of fabric.

[0075] Example 6

[0076] A photothermal conversion coating, which differs from Example 1 in that the substrate is cotton.

[0077] Example 7

[0078] A photothermal conversion coating, the preparation steps of which include:

[0079] 1. Place clean, untreated wood in 100mL of ethanol solution containing 0.81g of FeCl3. After the wood surface is completely impregnated, remove it and dry it in an oven at 40℃ for 10min to obtain the modified substrate.

[0080] 2. Place the modified substrate from step 1 above and the ethanol solution containing 3 mL of 0.05 mM EDOT (3,4-ethylenedioxythiophene) separately in the same glass container. Then, place the sealed glass container in an oven and heat it to 150°C for 4 hours. After that, take out the substrate, wash it with water 3 times, and let it dry naturally. A Cl-PEDOT photothermal coating will grow in situ on the wood surface.

[0081] Example 8

[0082] A photothermal conversion coating, the preparation steps of which include:

[0083] 1. Place clean, untreated wood in 100mL of ethanol solution containing 8.1g of FeCl3. After the wood surface is completely impregnated, remove it and dry it in an oven at 40℃ for 10min to obtain the modified substrate.

[0084] 2. Place the modified substrate from step 1 above and the ethanol solution containing 3 mL of 0.05 mM pyrrole monomer separately in the same glass container. Then, place the sealed glass container in an oven and heat it to 150°C for 2 hours. After that, take out the substrate, wash it with water 3 times, and let it dry naturally. A Cl-PPY photothermal coating will grow in situ on the wood surface.

[0085] Example 9

[0086] A photothermal conversion coating, the preparation steps of which include:

[0087] 1. Place clean, untreated wood in 100mL of ethanol solution containing 6.7g CuCl2. After the wood surface is completely impregnated, remove it and dry it in an oven at 40℃ for 10min to obtain the modified substrate.

[0088] 2. The modified substrate from step 1 above, along with an ethanol solution containing 3 mL of 0.05 mM EDOT (3,4-ethylenedioxythiophene) and 10 μL of 36 wt% hydrochloric acid solution, were placed separately in the same glass container. The sealed glass container was then placed in an oven and heated to 150°C for 4 hours. After that, the substrate was removed, washed three times with water, and allowed to air dry. A Cl-PEDOT photothermal coating was then grown in situ on the wood surface.

[0089] Example 10

[0090] A photothermal conversion coating, which differs from Example 1 in that:

[0091] 1. Place clean, untreated wood in 100mL of ethanol solution containing 10.0g of Fe2(SO4)3. After the wood surface is completely impregnated, remove it and dry it in an oven at 40℃ for 10min to obtain the modified substrate.

[0092] 2. The modified substrate from step 1 above, along with an ethanol solution containing 3 mL of 0.05 mM EDOT (3,4-ethylenedioxythiophene) and 10 μL of 36 wt% hydrochloric acid solution, were placed separately in the same glass container. The sealed glass container was then placed in an oven and heated to 150°C for 4 hours. After that, the substrate was removed, washed three times with water, and allowed to air dry. A Cl-PEDOT photothermal coating was then grown in situ on the wood surface.

[0093] Comparative Example 1

[0094] 1. Place clean, untreated wood in 100mL of ethanol solution containing 8.1g of FeCl3. After the wood surface is completely impregnated, remove it and dry it in an oven at 40℃ for 10min to obtain the modified substrate.

[0095] 2. The modified substrate from step 1 above is immersed in an ethanol solution containing 100 mL of 0.05 mM EDOT (3,4-ethylenedioxythiophene). After heating and refluxing at 130°C for 24 hours, the substrate is removed, washed with water 3 times, and air-dried. A Cl-PEDOT photothermal coating is grown in situ on the wood surface.

[0096] Furthermore, to verify the progressiveness of the embodiments of this application, the following performance tests were conducted:

[0097] 1. The morphology of the photoelectric conversion coatings grown on different substrates in Examples 1-6 was observed, and the actual images and electron microscope scan images are attached. Figure 3 As shown in the figures, 1-6 represent the original morphology of the substrate; after in-situ growth of the photothermal conversion coating, all substrates turn black; 1-wood, 2-rock wool, 3-chemical fiber, 4-filter paper, 5-ceramic, and 6-cotton are electron microscope images of the photothermal conversion coatings grown in situ on different substrates. As can be seen from the figures, the photothermal conversion coating of this application can grow in situ in a vine-like manner on different substrates such as wood, rock wool, chemical fiber fabrics, filter paper, ceramic filter screens, and cotton, and is firmly bonded to different substrates. Furthermore, the photothermal conversion coatings formed on different substrates are all black, exhibiting high light absorption efficiency and improving the coating's light utilization rate.

[0098] 2. Qualitative analysis was performed on the Cl-PEDOT coating grown in situ on the wood surface in Example 1. X-ray diffraction (PXRD) patterns were analyzed. (See attached image.) Figure 4 (a); Raman spectroscopy test, attached Figure 4 (b); ATR-FTIR Fourier transform attenuated total reflectance infrared spectroscopy test, attached Figure 4 (c). As can be seen from the test diagram, the coating grown in situ on the wood surface in Example 1 of this application is Cl-PEDOT.

[0099] 3. The surface temperature-time curve of the Cl-PEDOT coating grown in situ on the rock wool substrate in Example 2 was measured, and the test results are attached. Figure 5 As shown in (a), the temperature of uncoated rock wool rises very little under the same light conditions, but the temperature of rock wool modified with Cl-PEDOT coating rises rapidly to 90°C; however, after the light stops, the temperature quickly returns to its original value.

[0100] During the photothermal de-icing process, the surface temperature-time curve of the Cl-PEDOT coating grown in situ on the rock wool surface in Example 2 was measured, and the test results are attached. Figure 5 As shown in (b), under light conditions, ice melted within 6 minutes on rock wool with Cl-PEDOT coating grown in situ on the surface.

[0101] The photothermal conversion performance of the Cl-PEDOT coating grown in situ on the surface of the rock wool substrate in Example 2 was measured under outdoor sunlight. The test results are attached. Figure 5 As shown in (c), the surface temperature can reach 74.2°C under 0.6 hours of sunlight outdoors;

[0102] From the appendix Figure 5 As can be seen from (a) to (c), the coating surface prepared in the embodiments of this application can rapidly convert light energy into heat energy under sunlight, with the surface temperature rising rapidly by tens of degrees within minutes. This indicates that the coating material has extremely high photothermal conversion efficiency and is a poor conductor of heat, making it difficult for heat to dissipate and exhibiting good heat accumulation properties. This also demonstrates that this coating is an ideal photothermal conversion interface material.

[0103] 4. The enthalpy of evaporation of water in the photoelectric conversion coatings grown on different substrates in Examples 1-6 were tested respectively. The test results are shown in the attached figure. Figure 6 As shown in (a);

[0104] Using pure water as a control, the water mass loss on the surface of the photoelectric conversion coatings grown on different substrates in Examples 1-6 was measured, and the test results are attached. Figure 6 As shown in (b);

[0105] The water evaporation rate and light-to-vapor conversion linearity of the photoelectric conversion coatings grown on different substrates in Examples 1-6 were tested. The test results are shown in the attached figure. Figure 6 As shown in (c);

[0106] 5. The photothermal heat exchange coating grown on the wood surface in Example 1 was used to make a solar water evaporation-condensation device. A schematic diagram of the preparation process is attached. Figure 7 As shown in (a), the photothermal heat exchange coating grown on the wood surface is placed on top of a foam insulation board covered with a layer of hydrophilic gauze. A 7mm diameter through-hole is drilled in the center of the foam board, through which the gauze passes and connects to the upper layer of gauze to facilitate moisture transfer and reduce heat loss. A xenon lamp is used as the light source to simulate a solar water evaporation environment. The evaporation system is placed on an analytical electronic balance, and the water mass change is recorded every 2 minutes using computer data recording software (METTLER TOLEDO SerialPortToKeyboard).

[0107] The solar water evaporation data and outdoor light intensity changes of the solar water evaporation-condensation device were recorded outdoors from 10:00 to 17:00, as shown in the attached figure. Figure 7 As shown in (b), the changes in outdoor solar radiation intensity and clean aquatic quality over time were measured and recorded. From 10:00 to 16:00, the solar flux remained at 40-60 mW / cm². -2The rate of pure water production showed a continuous increasing trend during the midday period. During the daytime test (8 hours), the clean water production of this solar evaporator was 5.87 kg m³. -2 This demonstrates promising prospects for outdoor water purification applications.

[0108] 6. The photothermal conversion performance, surface hydrophobicity, water evaporation rate, and energy utilization rate of the photothermal conversion coatings prepared in each embodiment and comparative example were measured. Specifically:

[0109] ① Photothermal conversion performance testing methods / steps:

[0110] The photothermal conversion performance of a sample is measured by ΔT, which is the difference between the equilibrium surface temperature (Tc) and room temperature (Tr) within 1 minute under simulated sunlight irradiation. -2 Multiple coated substrates were placed on a polystyrene foam board plane perpendicular to the simulated light, ensuring a windless environment. The surface temperature of the substrates was recorded over time using an infrared thermal imaging camera by timing the process.

[0111] ② Surface hydrophilicity test:

[0112] The contact angles of surface water on various substrates obtained in the examples were directly measured using an OCA-20 contact angle analyzer (Germany).

[0113] ③ Water evaporation rate test:

[0114] Evaporators with various coated substrates were placed on top of a foam insulation board covered with a layer of hydrophilic gauze. A 7mm diameter through-hole was drilled in the center of the foam board, through which the gauze passed and connected to the upper layer of gauze to facilitate moisture transfer and reduce heat loss. A xenon lamp was used as the light source to simulate a solar water evaporation environment. In a windless environment, the evaporation system was placed on an analytical electronic balance, and the mass change of the water was recorded every 2 minutes using computer data recording software (METTLER TOLEDO Serial Port ToKey board).

[0115] ④ Energy utilization rate testing and calculation:

[0116] First, assume that water evaporation requires the same energy input (U). in The enthalpy of vaporization of bulk water and water on the Cl-PEDOT coated substrate are ΔH, respectively. bu ΔH ac The changes in water mass are respectively m bu m ac The relationship between them can be defined as:

[0117] U in =ΔH bu m bu =ΔH ac m ac

[0118] As attached Figure 6 As shown in (a), the actual enthalpy of evaporation (ΔH) of water on wood, rock wool, ceramic filter screens, filter paper, and fabrics modified with Cl-PEDOT coatings prepared in Examples 1-5 was calculated. ac The values ​​are 1673.71, 1905.52, 2002.89, 1816.89, and 1630.71 Jg, respectively. -1 .

[0119] To further evaluate the steam generation performance of the substrate after Cl-PEDOT coating modification, we calculated the solar-to-steam conversion efficiency (η) using the following formula:

[0120]

[0121] in, It is the mass flux, I is the power density of sunlight irradiating the sample surface, and ΔH is the mass flux. ac It is the equivalent enthalpy of vaporization of water. (See attached image.) Figure 6 As shown in (c), the solar-to-steam conversion efficiency of planar wood, rock wool, etc., coated with Cl-PEDOT and other coatings is calculated under sunlight.

[0122] The test results are shown in Table 1 below:

[0123] Table 1

[0124]

[0125]

[0126] The test results above show that the photothermal conversion coating prepared in Example 1 exhibits the best photothermal conversion performance, surface hydrophilicity, water evaporation rate, and energy utilization rate. The photothermal conversion coatings prepared by gas-phase polymerization in Examples 1-10 all demonstrate better photothermal conversion performance, surface hydrophilicity, water evaporation rate, and energy utilization rate than the photothermal conversion coating prepared by dip coating in Comparative Example 1. Furthermore, the photothermal conversion coatings prepared by pre-adsorbing the chlorine source in situ into the substrate using an initiator in Examples 1-9, compared to the photothermal conversion coating prepared by separately adding the chlorine source in Example 10, exhibit better photothermal conversion performance, surface hydrophilicity, water evaporation rate, and energy utilization rate.

[0127] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a photothermal conversion coating, characterized in that, Including the following steps: A porous substrate is obtained, and an initiator is adsorbed in situ into the porous substrate to obtain a modified porous substrate; the initiator is selected from ferric chloride, and the modified porous substrate is adsorbed with ferric chloride initiator; the step of adsorbing the initiator in situ into the porous substrate includes: immersing the porous substrate in a solution of the initiator and drying it to obtain the modified porous substrate adsorbed with the initiator; A conjugated polymer monomer and a chlorine source are subjected to a gas-phase polymerization reaction with the modified porous substrate to form a chlorine-doped photothermal conversion coating in situ on the surface of the porous substrate. The gas-phase polymerization reaction includes: mixing the conjugated polymer monomer and the chlorine source with the modified porous substrate in the gas phase and reacting for 2 to 4 hours to form the chlorine-doped photothermal conversion coating in situ on the surface of the porous substrate.

2. The method for preparing the photothermal conversion coating as described in claim 1, characterized in that, The porous substrate is selected from at least one of wood, rock wool, ceramic mesh, filter paper, fabric, and cotton; And / or, the conjugated polymer monomer is selected from at least one of pyrrole and 3,4-ethylenedioxythiophene.

3. The method for preparing the photothermal conversion coating as described in claim 2, characterized in that, The molar ratio of the initiator, the chlorine source, and the conjugated polymer monomer is 1:(3-5):(1000-10000); And / or, the concentration of the initiator soaking solution is 0.05 mol / L to 0.5 mol / L.

4. A photothermal conversion coating prepared by the method according to any one of claims 1 to 3, characterized in that, The photothermal conversion coating is similar to the structure of a Virginia creeper, growing in situ and adhering to the substrate surface. It includes a chlorine-doped conjugated polymer. The photothermal conversion coating has a wrinkled structuring effect, which enables multiple reflections and absorptions of incident light in the microstructure of the photothermal conversion coating. The conjugated polymer in the photothermal conversion coating is doped with chloride ions.

5. The photothermal conversion coating as described in claim 4, characterized in that, The mass percentage of chloride ions in the photothermal conversion coating is 0.01% to 0.005%. And / or, the substrate includes at least one of wood, rock wool, ceramic mesh, filter paper, fabric, and cotton; And / or, the conjugated polymer includes at least one of polypyrrole and polythiophene.

6. The photothermal conversion coating as described in claim 5, characterized in that, The chlorine-doped conjugated polymer is selected from chlorine-doped polythiophene; And / or, the chlorine-doped conjugated polymer is black.

7. A photothermal conversion device, characterized in that, The functional layer of the photothermal conversion device includes the photothermal conversion coating as described in any one of claims 4 to 6.

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