Evaporator device and method of manufacturing the same

Abstract

The application discloses an evaporation device and a preparation method thereof. The evaporation device comprises a heat-conducting substrate and a hydrophobic light-heat conversion layer. The heat-conducting substrate is provided with a plurality of through holes penetrating the top surface and the bottom surface of the heat-conducting substrate. The bottom surface of the heat-conducting substrate and the hole wall of the through hole are subjected to hydrophilic treatment. The hydrophobic light-heat conversion layer covers the top surface of the heat-conducting substrate. The evaporation device and the preparation method thereof can significantly improve the evaporation efficiency of the evaporation device, and can realize directional precipitation of salt crystals at the through hole, so as to avoid salt precipitation on the light-heat conversion layer and affect the light-heat conversion efficiency of the light-heat conversion layer.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to an evaporation device and its preparation method. Background Technology

[0002] Freshwater resources are a precious natural resource upon which human society depends for survival and development. With the continuous growth of the global population and the acceleration of industrialization, the demand for freshwater resources is increasing daily. The scarcity of freshwater resources makes the rational development and utilization of water resources a global challenge.

[0003] To alleviate the shortage of freshwater resources, various seawater desalination and wastewater treatment technologies have been developed. These technologies mainly include reverse osmosis, multi-effect distillation, and electrodialysis, which can convert seawater or wastewater into usable freshwater. While these technologies have alleviated the pressure on freshwater resources to some extent, they have also brought a series of problems. First, these technologies require expensive infrastructure investment, which is a heavy economic burden for many countries and regions. Second, these technologies have huge energy demands, consuming large amounts of high-quality heat energy or electricity during implementation, which not only increases operating costs but also has a certain impact on the environment.

[0004] Solar energy, as a clean and renewable energy source, is increasingly being applied to seawater desalination and wastewater treatment. Natural evaporation is one of the main sources of freshwater on land, and inspired by this, researchers have begun exploring the use of solar energy to drive water evaporation and improve the efficiency of freshwater acquisition. However, in reality, seawater has poor light absorption properties, and the barrier effect of salt content results in low natural evaporation efficiency, which limits the application and development of solar-driven water evaporation technology.

[0005] Therefore, it is necessary to provide a new solution to the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide an evaporation device and its preparation method, which has high evaporation efficiency and can reduce the impact of salt crystal precipitation on the photothermal interface during evaporation.

[0007] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0008] In a first aspect, the present invention provides an evaporation device comprising: a thermally conductive substrate and a hydrophobic photothermal conversion layer; the thermally conductive substrate has a plurality of through holes penetrating the top and bottom surfaces of the thermally conductive substrate, the bottom surface of the thermally conductive substrate and the hole walls of the through holes being hydrophilic; the hydrophobic photothermal conversion layer covers the top surface of the thermally conductive substrate.

[0009] In one or more embodiments, the hydrophobic photothermal conversion layer includes a hydrophobically modified photothermal conversion material, wherein the photothermal conversion material includes CoNiCuMnAl@C.

[0010] In one or more embodiments, the water contact angle of the hydrophobic photothermal conversion layer is greater than 90°; and / or the water contact angle between the bottom surface of the thermally conductive substrate and the hole wall of the through hole after hydrophilic treatment is less than 30°.

[0011] In one or more embodiments, the thickness of the thermally conductive substrate is 0.5 to 1 mm; and / or the diameter of the through hole is 2 to 5 mm.

[0012] In one or more embodiments, the bottom surface of the thermally conductive substrate is provided with a water-conducting layer, which is made of a water-conducting material.

[0013] In one or more embodiments, the bottom surface of the water conveying layer is provided with a heat insulation layer, the heat insulation layer is provided with water conveying holes that penetrate the top and bottom surfaces of the heat insulation layer, the water conveying holes are filled with water-conducting filler, and the water-conducting filler is in contact with the water conveying layer.

[0014] In a second aspect, the present invention provides a method for preparing an evaporation device, comprising:

[0015] A thermally conductive substrate and a photothermal conversion material are prepared. The thermally conductive substrate has multiple through holes penetrating its top and bottom surfaces. The photothermal conversion material is hydrophobically modified. The hydrophobically modified photothermal conversion material is deposited on the top surface of the thermally conductive substrate. The bottom surface of the thermally conductive substrate and the walls of the through holes are hydrophilically treated.

[0016] In one or more embodiments, the thermally conductive substrate is prepared by means of:

[0017] The top surface of the thermally conductive substrate is scanned using a laser to create a micron-level trench structure. After the scanning is completed, the thermally conductive substrate is cleaned and dried.

[0018] In one or more embodiments, the photothermal conversion material is prepared by means of:

[0019] Cobalt acetate, nickel acetate tetrahydrate, copper acetate monohydrate, and manganese acetate were weighed and added to N,N-dimethylformamide. The mixture was stirred until homogeneous to obtain mixture A. Terephthalic acid was added to mixture A, and the mixture was stirred vigorously for 1–3 hours to obtain mixture B. Mixture B was centrifuged to obtain a precipitate. The precipitate was washed by centrifugation with N,N-dimethylformamide, and the precipitate was collected and vacuum dried. The dried precipitate was ground into powder to obtain a high-entropy alloy MOF precursor. The high-entropy alloy MOF precursor material was transferred to a tube furnace and subjected to argon-hydrogenation... Under mixed gas conditions, the furnace temperature was raised to 680–720°C at a heating rate of 5°C per minute. After calcination for 1–2 hours, the temperature was lowered to room temperature to obtain a calcined black powder. The calcined black powder was added to a dilute sulfuric acid solution with a concentration of 3–6 mmol / L and ultrasonically dispersed to obtain a mixed solution C. The mixed solution C was placed in an environment of 60–80°C, and impurities in the black powder were etched by sulfuric acid. After etching, the mixed solution C was centrifuged, and the black precipitate was collected, washed, and dried to obtain CoNiCuMnAl@C photothermal conversion material.

[0020] In one or more embodiments, the hydrophilic treatment of the bottom surface of the thermally conductive substrate and the hole wall of the through hole includes: scanning the bottom surface of the thermally conductive substrate and the hole wall of the through hole with a laser.

[0021] Compared with the prior art, the evaporation device and preparation method provided by the present invention, by setting multiple through holes penetrating the top and bottom surfaces of the thermally conductive substrate, and by performing hydrophilic treatment on the bottom surface of the thermally conductive substrate and the hole walls, allows the hydrophobic photothermal conversion layer to cover the top surface of the thermally conductive substrate, which can significantly improve the evaporation efficiency of the evaporation device, and can also achieve the directional precipitation of salt crystals at the through holes, avoiding the occurrence of salt precipitation on the photothermal conversion layer and affecting the photothermal conversion efficiency of the photothermal conversion layer. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, 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 recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the evaporation device in one embodiment of the present invention;

[0024] Figure 2 This is a morphology diagram of the hydrophobic modified photothermal conversion material prepared in Example 1 of the present invention;

[0025] Figure 3 This is a comparison chart of the evaporation amounts of the evaporation devices prepared in Examples 1-3 of the present invention;

[0026] Figure 4 This is a comparison chart of the evaporation amounts of the evaporation devices prepared in Example 2 and Comparative Example 1 of the present invention.

[0027] Figure 5 This is a salt precipitation state diagram of the evaporation device prepared in Example 1 of the present invention after a 180-minute test;

[0028] Figure 6 This is a salting-out state diagram of the evaporation device prepared in Example 1 of the present invention every 10 minutes;

[0029] Figure 7 This is a salt precipitation state diagram of the evaporation device prepared in Example 2 of the present invention after a 180-minute test;

[0030] Figure 8 This is a salting-out state diagram of the evaporation device prepared in Example 2 of the present invention, taken every 10 minutes.

[0031] Figure 9 This is a salt precipitation state diagram of the evaporation device prepared in Example 3 of the present invention after a 180-minute test;

[0032] Figure 10 This is a salting-out state diagram of the evaporation device prepared in Example 3 of the present invention every 10 minutes.

[0033] Explanation of key figure labels:

[0034] 11- Thermally conductive substrate, 111- Through hole, 12- Hydrophobic photothermal conversion layer, 13- Water transport layer, 14- Thermal insulation layer, 15- Water-conducting filler. Detailed Implementation

[0035] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0036] It should be noted that, unless otherwise specified, all figures used in this specification and claims to represent feature dimensions, quantities, and physical properties should be understood to be modified by the term "about" in all cases. Therefore, unless stated to the contrary, the numerical parameters listed in the foregoing specification and appended claims are approximations, and those skilled in the art can appropriately modify these approximations to obtain the desired characteristics using the teachings disclosed herein. The use of numerical ranges indicated by endpoints includes all numbers within that range and any range within that range; for example, 1 to 5 includes 1, 1.2, 1.4, 1.55, 2, 2.75, 3, 3.80, 4, and 5, etc.

[0037] With the increasing severity of the global freshwater shortage, seawater desalination technology has become an important means for humans to obtain freshwater. However, existing seawater desalination technologies, such as reverse osmosis, multi-effect distillation, and electrodialysis, while able to alleviate freshwater shortages to some extent, still have many problems in their application, such as high equipment costs, high energy consumption, and reduced efficiency due to salt deposition.

[0038] A prominent problem in existing technologies is that salt deposition on the photothermal conversion layer significantly reduces photothermal conversion efficiency, thus affecting the efficiency of the entire evaporation process. This is because salt accumulation covers the photothermal conversion layer, hindering its ability to absorb solar energy. Furthermore, the complexity of existing equipment and high operating and maintenance costs limit its large-scale application. Therefore, how to improve evaporation efficiency while reducing energy consumption and simplifying equipment design has become a pressing technical challenge.

[0039] The technical approach of this invention lies in proposing a novel evaporation device through innovative structural design and material selection, aiming to effectively solve the problems in the prior art. The core idea of ​​this invention is to utilize the combination of hydrophilic and hydrophobic properties on both sides of the device to achieve directional salt growth during evaporation, preventing salt from covering the photothermal conversion layer, thereby improving both photothermal conversion efficiency and evaporation efficiency.

[0040] Specifically, this invention designs multiple through-holes penetrating the top and bottom surfaces of a thermally conductive substrate, and applies a hydrophilic treatment to the hole walls and bottom surface. Simultaneously, a hydrophobic photothermal conversion layer is coated on the top surface of the thermally conductive substrate. In this structure, liquid can rapidly enter the through-holes through the hydrophilic hole walls, while salts grow directionally on the hole walls during evaporation, avoiding the formation of a photothermal conversion layer. This innovative design not only improves evaporation efficiency but also reduces energy consumption and simplifies equipment complexity.

[0041] Please refer to Figure 1As shown, an evaporation device according to an embodiment of the present invention includes a thermally conductive substrate 11 and a hydrophobic photothermal conversion layer 12. The thermally conductive substrate 11 has a plurality of through holes 111 penetrating its top and bottom surfaces. The bottom surface of the thermally conductive substrate 11 and the walls of the through holes 111 are hydrophilically treated. The hydrophobic photothermal conversion layer 12 covers the top surface of the thermally conductive substrate 11.

[0042] It should be noted that the thermally conductive substrate 11 of the evaporation device has multiple through holes 111 penetrating the top and bottom surfaces. The bottom surface of the thermally conductive substrate 11 and the walls of the through holes 111 are hydrophilically treated to give them good wettability. When the evaporation device comes into contact with liquid, the liquid can quickly wet the hole walls and enter the through holes 111. This design allows the liquid to fully contact each through hole 111 of the substrate, thereby providing a sufficient liquid supply for the subsequent evaporation process.

[0043] The top surface of the thermally conductive substrate 11 is covered with a hydrophobic photothermal conversion layer 12. The hydrophobic design effectively prevents the formation of a continuous liquid film on the photothermal conversion layer, thereby avoiding the precipitation and coverage of salt on the photothermal conversion layer. This design ensures that the photothermal conversion layer is always exposed to the air, maximizing the absorption of solar energy and its conversion into heat energy, thus improving evaporation efficiency.

[0044] The evaporation device has a hydrophilic side (pore walls and bottom surface) and a hydrophobic side (top surface). This structure effectively controls the precipitation location of salts during the evaporation process. Because the hydrophilic pore walls attract and retain the liquid, salts gradually precipitate on the pore walls during evaporation and grow directionally toward the top surface of the substrate.

[0045] When salt crystals begin to grow on the pore walls, a thin liquid film forms on the surface of the salt crystals. This liquid film continuously transports liquid to the surface of the salt crystals, allowing new salt crystals to continue growing on top of the existing ones. This directional growth mechanism effectively controls the salt content within the via 111 region, thus preventing salt deposition on the photothermal conversion layer and ensuring that the photothermal conversion layer maintains its high-efficiency photothermal conversion performance unaffected by salt coverage.

[0046] Specifically, when the evaporation device comes into contact with a liquid (such as seawater), the liquid first wets the bottom surface of the thermally conductive substrate 11 and the surface of the hole wall 111. This is because the hole wall is hydrophilic, possessing strong wettability, allowing the liquid to quickly penetrate and fill the hole 111. The hydrophilic surface attracts water molecules, ensuring that the liquid is evenly distributed on the hole wall surface, thereby providing sufficient liquid supply for the evaporation process.

[0047] As the evaporation process continues, water molecules evaporate from both the pore wall surface and the surface of the liquid inside the pore. Because the pore wall is hydrophilic, the liquid preferentially evaporates along the pore wall, causing salt to gradually concentrate and precipitate on the pore wall surface. Salt precipitation occurs first on the pore wall because the liquid on the pore wall evaporates more easily than the liquid inside the through-hole 111.

[0048] Once salt begins to precipitate and form initial salt crystals on the pore wall surface, a thin liquid film forms on the crystal surface. This liquid film continues to transport liquid to the salt crystal surface. This is due to the capillary action of the liquid film, which attracts and retains water molecules, thus continuously supplying liquid to the salt crystal surface. As the water in the liquid film evaporates, new salt continues to precipitate and grow on top of the original salt crystal. This process results in the phenomenon of salt directional growth along the pore wall.

[0049] Since salts mainly grow directionally on the surface and inside the pores, and the hydrophobic photothermal conversion layer 12 on the top surface of the thermally conductive substrate 11 is not easily wetted by liquids, salts will not precipitate on the photothermal conversion layer. This design effectively prevents salts from covering the photothermal conversion layer, ensuring that the photothermal conversion layer is always exposed to the air, maximizing the absorption of solar energy and its conversion into heat energy, thereby improving evaporation efficiency.

[0050] In one exemplary embodiment, the hydrophobic photothermal conversion layer 12 includes a hydrophobically modified photothermal conversion material, which comprises CoNiCuMnAl@C (carbon-encapsulated high-entropy alloy). High-entropy alloys are alloys composed of multiple elements mixed in near-equal atomic ratios, exhibiting excellent thermal stability and mechanical properties. During photothermal conversion, high-entropy alloys can withstand high temperatures without performance degradation. Carbon materials possess excellent photothermal conversion efficiency and chemical stability. The carbon-encapsulated structure not only improves the photothermal stability of the high-entropy alloy but also enhances its ability to absorb solar energy.

[0051] The core performance characteristic of photothermal conversion materials is their efficiency in converting light energy into heat energy. Carbon-encapsulated high-entropy alloys (CoNiCuMnAl@C) exhibit excellent photothermal conversion performance. Due to their complex composition and structure, high-entropy alloys can efficiently absorb solar energy across a wide wavelength range and rapidly convert it into heat energy. Simultaneously, carbon materials possess high light absorption efficiency and thermal conductivity, further enhancing the photothermal conversion efficiency. Moreover, high-entropy alloys exhibit excellent thermal stability and corrosion resistance, maintaining stable performance in high-temperature and corrosive environments. This allows the photothermal conversion layer to be used for extended periods without being affected by environmental factors.

[0052] In one exemplary embodiment, the water contact angle of the hydrophobic photothermal conversion layer 12 is greater than 90°; the water contact angle between the bottom surface of the thermally conductive substrate 11 after hydrophilic treatment and the hole wall of the through hole 111 is less than 30°.

[0053] The design goal of the hydrophobic photothermal conversion layer 12 is to prevent liquid from forming a liquid film on the surface, thereby ensuring photothermal conversion efficiency. The water contact angle is an important parameter for measuring surface wettability; a contact angle greater than 90° indicates high hydrophobicity, meaning water droplets form spherical shapes on the surface without spreading. The hydrophobic surface prevents liquid from covering the photothermal conversion layer, ensuring its surface is always exposed to air. In this way, the photothermal conversion layer can absorb solar energy to the maximum extent and efficiently convert it into heat energy for water evaporation.

[0054] The hydrophobic surface prevents the spread and retention of liquids on the photothermal conversion layer, thus avoiding salt precipitation. This design effectively prevents salt from covering the photothermal conversion layer, maintaining its long-term high efficiency in photothermal conversion. Furthermore, the hydrophobic surface has self-cleaning properties; water droplets rolling on the surface can carry away dust and impurities. This characteristic helps maintain the cleanliness of the photothermal conversion layer, further improving its photothermal conversion efficiency.

[0055] The bottom surface of the thermally conductive substrate 11 and the walls of the through-holes 111 are hydrophilically treated, with a water contact angle of less than 30°, indicating strong hydrophilicity, meaning that liquids can spread rapidly on the surface. The hydrophilic thermally conductive substrate 11 can quickly attract liquids, allowing them to be evenly distributed on the hole walls and bottom surface. This design ensures a sufficient liquid supply during evaporation, thus maintaining continuous water evaporation. During evaporation, the liquid first evaporates on the hydrophilic hole walls, and salts gradually precipitate on the hole walls.

[0056] Due to the hydrophilicity of the pore walls, salt can grow directionally on the pore walls, avoiding the covering of the photothermal conversion layer. The design of the hydrophilic pore walls allows salt to gradually accumulate on the pore surface and grow outwards, thus achieving effective control over salt leaching. Furthermore, the hydrophilic surface increases the diffusion rate of water molecules, accelerating the flow and evaporation process of the liquid on the pore walls. This design significantly improves evaporation efficiency, enabling the evaporator to evaporate more water per unit time.

[0057] In one exemplary embodiment, the thickness of the thermally conductive substrate 11 is 0.5 to 1 mm; the diameter of the through hole 111 is 2 to 5 mm.

[0058] The main function of the thermally conductive substrate 11 is to effectively conduct the solar energy absorbed by the photothermal conversion layer to the liquid, causing it to evaporate rapidly. A moderate thickness (0.5–1 mm) ensures that the substrate has sufficient mechanical strength and thermal conductivity. If the substrate is too thick, the thermal conductivity will decrease, affecting the evaporation rate; if it is too thin, the substrate will lack mechanical strength and be easily damaged during use.

[0059] The moderate pore size design (2–5 mm) facilitates the directional precipitation of salt on the pore walls. The smaller pore size provides sufficient surface area, allowing salt to grow gradually along the pore walls without forming a coating on the photothermal conversion layer. This design ensures the directional precipitation process of salt on the pore walls, thus avoiding the problem of the photothermal conversion layer being covered by salt and maintaining efficient photothermal conversion performance.

[0060] If the pore size is too small (less than 2 mm), it is prone to clogging due to salt precipitation or impurity accumulation. Once the pore is clogged, the liquid supply is hindered, and the evaporation efficiency will be significantly reduced. Therefore, selecting an pore size in the range of 2 to 5 mm can effectively avoid clogging problems and ensure that the liquid can pass smoothly through the pore wall during the evaporation process.

[0061] Excessively large pore sizes reduce the effective photothermal conversion area, impacting evaporation efficiency. Larger pore sizes mean fewer holes need to be formed on the substrate, reducing the effective area of ​​the photothermal conversion layer and lowering the efficiency of solar energy absorption and thermal energy conversion. Therefore, pore sizes between 2 and 5 mm maximize the number and distribution of pores while preventing clogging, optimizing photothermal conversion and evaporation efficiency.

[0062] In one exemplary embodiment, a water-conducting layer 13 is provided on the bottom surface of the thermally conductive substrate 11, the water-conducting layer 13 being made of a water-conducting material.

[0063] The core function of the evaporation device is to absorb solar energy through the photothermal conversion layer and convert it into heat energy for water evaporation. In order to maintain an efficient evaporation process, it is necessary to ensure that the liquid (such as seawater) can be continuously and stably supplied to the bottom surface of the thermally conductive substrate 11 and the walls of the through holes 111.

[0064] The water delivery layer 13 is provided to ensure that liquid can be continuously guided to the bottom surface of the heat-conducting substrate 11. The water delivery layer 13 is made of a water-conducting material (such as degreased cotton), which typically has high capillary force and can attract and conduct moisture. Through the water delivery layer 13, the liquid can be rapidly and evenly distributed on the bottom surface of the heat-conducting substrate 11, thereby ensuring that the evaporation device is always in optimal working condition.

[0065] The water-conducting layer 13, through its water-conducting properties, can uniformly distribute liquid onto the bottom surface of the heat-conducting substrate 11 and the walls of the through-holes 111. The water-conducting material typically possesses good wettability and capillary action, enabling it to rapidly absorb liquid and conduct it along the direction of the water-conducting layer 13. This design ensures uniform liquid distribution across the entire bottom surface of the heat-conducting substrate 11, optimizing the evaporation process.

[0066] Specifically, the bottom surface of the water conveying layer 13 is provided with a heat insulation layer 14, the heat insulation layer 14 is provided with water conveying holes that penetrate the top and bottom surfaces of the heat insulation layer 14, the water conveying holes are filled with water-conducting filler 15, and the water-conducting filler 15 is in contact with the water conveying layer 13.

[0067] The evaporation process relies on the photothermal conversion layer to convert solar energy into heat energy, thereby heating the liquid and promoting evaporation. The insulation layer 14 prevents the thermally conductive substrate 11 and the water delivery layer 13 from directly contacting the water, avoiding heat loss due to water at the bottom and reduced overall evaporation efficiency. The insulation layer 14 effectively prevents downward heat conduction, reducing heat loss. By providing the insulation layer 14 on the bottom surface of the water delivery layer 13, heat energy is concentrated near the thermally conductive substrate 11 and the photothermal conversion layer, thereby improving evaporation efficiency.

[0068] The insulation layer 14 has water inlets penetrating its top and bottom surfaces. These inlets guide water, allowing liquid to be transported from the water body through the insulation layer 14 to the water delivery layer 13. The water-conducting filler 15 (such as absorbent cotton) has good capillary action, attracting and retaining the liquid and transporting it from the water body to the water delivery layer 13. Through capillary action, the water-conducting filler 15 can continuously supply liquid, ensuring an uninterrupted evaporation process.

[0069] The insulation layer 14 is preferably made of polystyrene foam. Polystyrene foam has good thermal resistance properties, which can effectively prevent heat conduction. At the same time, polystyrene foam has a low density and good buoyancy, allowing the evaporation device to float on the water surface.

[0070] One embodiment of the present invention provides a method for preparing the aforementioned evaporation device, which specifically includes the following steps:

[0071] S201: Prepare a thermally conductive substrate and a photothermal conversion material. The thermally conductive substrate has multiple through holes penetrating its top and bottom surfaces.

[0072] Thermally conductive substrates are typically made of materials with high thermal conductivity, such as metals like aluminum and copper, or ceramic materials with high thermal conductivity. These materials can rapidly conduct heat, thereby improving evaporation efficiency. Multiple through-holes, ranging in diameter from 2 to 5 mm, are provided on the thermally conductive substrate, penetrating its top and bottom surfaces. The purpose of the through-hole design is to provide a path for liquid evaporation and to promote the directional precipitation of salts on the pore walls.

[0073] Photothermal conversion materials need to possess highly efficient photothermal conversion capabilities, such as carbon-encapsulated high-entropy alloys (CoNiCuMnAl@C). This material exhibits excellent light absorption performance over a wide wavelength range and can rapidly convert light energy into heat energy.

[0074] In one exemplary embodiment, the preparation method of the thermal substrate specifically includes: using a laser to scan the top surface of the thermally conductive substrate to form a micron-level trench structure on the top surface of the thermally conductive substrate; after the scanning is completed, the thermally conductive substrate is cleaned and dried.

[0075] Micrometer-scale trench structures can significantly increase the surface area of ​​the thermally conductive substrate, thereby improving the adhesion of the photothermal conversion layer. This structure provides more adhesion points for the photothermal conversion material, ensuring more uniform and stable deposition. The trench structure helps reduce light reflection and scattering, allowing more light energy to be absorbed and utilized, enhancing the light absorption capacity of the photothermal conversion layer, and improving the photothermal conversion efficiency.

[0076] During laser etching, tiny particles, molten material, and other impurities may remain on the substrate surface. These impurities can affect the deposition quality and adhesion of the photothermal conversion layer. A cleaning process can be used to ensure the cleanliness of the substrate surface. Cleaning methods can include ultrasonic cleaning, chemical solvent cleaning, and deionized water cleaning. Ultrasonic cleaning uses high-frequency vibration to remove surface deposits, chemical solvents can dissolve organic matter, and deionized water cleaning can remove inorganic particles and ionic impurities.

[0077] In an exemplary embodiment, the preparation method of the photothermal conversion material specifically includes: weighing cobalt acetate, nickel acetate tetrahydrate, copper acetate monohydrate, and manganese acetate, and adding them to N,N-dimethylformamide, stirring evenly to obtain mixture A; adding terephthalic acid to mixture A, stirring vigorously for 1-3 hours to obtain mixture B; centrifuging mixture B to obtain a precipitate; washing the precipitate with N,N-dimethylformamide by centrifugation, collecting the precipitate and vacuum drying; grinding the dried precipitate into powder to obtain a high-entropy alloy MOF (metal-organic framework) precursor; and then... The OF precursor material was transferred to a tube furnace, and under argon-hydrogen mixed gas conditions, the furnace temperature was raised to 680–720°C at a heating rate of 5°C per minute. After calcination for 1–2 hours, the temperature was lowered to room temperature to obtain a calcined black powder. The calcined black powder was added to a dilute sulfuric acid solution with a concentration of 3–6 mmol / L and ultrasonically dispersed to obtain a mixture C. The mixture C was placed in an environment of 60–80°C, and impurities in the black powder were etched by sulfuric acid. After etching, the mixture C was centrifuged, and the black precipitate was collected, washed, and dried to obtain CoNiCuMnAl@C photothermal conversion material.

[0078] S202: Hydrophobic modification of photothermal conversion materials.

[0079] By modifying photothermal conversion materials to be hydrophobic, a hydrophobic coating can be formed on the material surface, resulting in a water contact angle greater than 90°. The purpose of this hydrophobic treatment is to prevent the formation of a liquid film on the surface of the photothermal conversion material, thereby ensuring that the material surface is always exposed to air and maximizing photothermal conversion efficiency. Furthermore, the hydrophobic surface can reduce salt deposition on the material surface, extending the lifespan of the device.

[0080] In one exemplary embodiment, the hydrophobic modification method includes: weighing the photothermal conversion material, injecting it into an ethanol solution containing 3 wt% hexadecyltrimethoxysilane, and ultrasonically dispersing it; centrifuging the solution using a centrifuge, and drying the precipitate in an oven.

[0081] Hexadecyltrimethoxysilane (HDTMS) possesses a long-chain alkyl group (C16) and a trimethoxysilane group. The long-chain alkyl group provides hydrophobicity, while the trimethoxysilane group can form chemical bonds with the material surface, thereby giving the surface stable hydrophobicity. The trimethoxysilane group can form strong silicon-oxygen bonds (Si-O-Si) with hydroxyl groups (-OH) or other reactive groups on the material surface through hydrolysis and condensation reactions, ensuring the stability and durability of the hydrophobic layer.

[0082] S203: Deposit the hydrophobically modified photothermal conversion material on the top surface of the thermally conductive substrate.

[0083] The hydrophobically modified photothermal conversion material can be configured into an electrophoretic deposition solution, and the photothermal conversion material can be deposited on the top surface of a thermally conductive substrate by electrophoretic deposition to form a photothermal conversion layer.

[0084] Electrophoretic deposition is a method that uses an electric field to move charged particles in a solution and deposit them onto an electrode. Under the influence of the electric field, the deposited particles move along the direction of the electric field and form a uniform coating on the target substrate (electrode).

[0085] The thermally conductive substrate can be used as the working electrode (cathode or anode). The photothermal conversion material particles are charged (positive or negative) in the solution. Under the action of an external electric field, the charged particles move to the surface of the thermally conductive substrate and are deposited on it to form a uniform coating.

[0086] S204: Apply hydrophilic treatment to the bottom surface of the thermally conductive substrate and the walls of the through holes.

[0087] The purpose of hydrophilic treatment is to ensure that the liquid can quickly wet the bottom surface of the thermally conductive substrate and the walls of the through holes, thereby forming specific vapor pathways and enabling the directional precipitation of salts during evaporation. The hydrophilic surface can attract liquid and promote its rise along the hole walls, thereby achieving uniform distribution and continuous supply of liquid, ensuring the continuity and efficiency of the evaporation process.

[0088] In one exemplary embodiment, the hydrophilic treatment of the bottom surface of the thermally conductive substrate and the hole wall of the through hole includes: scanning the bottom surface of the thermally conductive substrate and the hole wall of the through hole with a laser.

[0089] Laser etching utilizes a high-energy laser beam to perform micro-machining on material surfaces. The laser beam can create micro / nano-scale structures on the material surface, increasing the surface area. Simultaneously, the high temperature alters the chemical bonds on the surface, forming more hydrophilic groups (such as hydroxyl groups). Laser etching can create micro / nano-scale trenches and protrusions on the surface of thermally conductive substrates. These microstructures increase surface roughness and specific surface area. Rough surfaces more easily trap and retain water molecules, thus improving the material's hydrophilicity. The presence of these microstructures enhances surface capillary action, allowing water molecules to diffuse and wet more easily between these structures, further improving hydrophilic properties.

[0090] The present invention will be further described below with reference to specific embodiments.

[0091] Example 1

[0092] 1. Preparation of hydrophobic photothermal conversion materials

[0093] Weigh out 1 mmol molar mass of each of the following five reagents: cobalt acetate, nickel acetate tetrahydrate, copper acetate monohydrate, and manganese acetate. Then, add them to 150 ml of N,N-dimethylformamide and stir vigorously with a magnetic stirrer for 5 min. Next, slowly add 5 mmol molar mass of terephthalic acid and continue stirring vigorously at room temperature for 2 h. Finally, centrifuge the resulting blue mixture at 8000 rpm for 2 min and wash three times with N,N-dimethylformamide. Dry the collected blue precipitate overnight in a vacuum oven at 60°C. The dried product is then finely ground to obtain the desired high-entropy alloy MOF precursor.

[0094] Next, the high-entropy alloy MOF precursor material was transferred to a tube furnace and calcined for 2 hours at a heating rate of 5°C per minute under an argon-hydrogen mixture (93% argon, 7% hydrogen). After the tube furnace temperature cooled to room temperature, the calcined black powder was collected for subsequent operations.

[0095] Subsequently, 200 mg of the calcined black powder was weighed and added to 50 ml of a 5 mmol / L dilute sulfuric acid solution. Then, the mixture was sonicated for 5 minutes to ensure more uniform dispersion of the material in the dilute sulfuric acid solution.

[0096] Then, the mixture and the beaker containing the solution were transferred to an oil bath and kept at 70°C for 6 hours to remove non-high-entropy alloy impurities from the prepared material through the etching effect of sulfuric acid. Subsequently, the etched solution was centrifuged and washed three times with deionized water at 8000 rpm for 2 minutes. Finally, the collected black precipitate was freeze-dried to obtain the prepared CoNiCuMnAl@C material.

[0097] Finally, 100 mg of the prepared CoNiCuMnAl@C material was added to a threaded reagent bottle, and 100 ml of an ethanol solution containing 3 wt% hexadecyltrimethoxysilane was injected. After tightening the cap, the reagent bottle was placed in an ultrasonic machine for one hour of ultrasonic treatment to ensure the material was evenly dispersed in the solution. During the ultrasonic process, the water in the ultrasonic machine needed to be changed regularly to maintain a low-temperature environment. After treatment, the threaded reagent bottle was transferred to room temperature (25°C) and allowed to stand for one hour. Finally, the solution was centrifuged to obtain the precipitate, which was then placed in an oven and kept at 110°C for 2 hours. After cooling, the final hydrophobically modified photothermal conversion material (such as...) was obtained. Figure 2 (As shown).

[0098] 2. Preparation of the light absorption layer

[0099] First, the aluminum sheet to be used for electrophoretic deposition needs to be pretreated. A pre-customized aluminum sheet (90mm long, 56mm wide, 0.8mm thick, with a 4×4 matrix of circular holes, 2mm in diameter) will be laser-etched onto the entire surface to be deposited. Next, the etched aluminum sheet will be ultrasonically cleaned for one hour. After cleaning, the aluminum sheet will be rinsed with anhydrous ethanol and deionized water, and then dried for later use.

[0100] The preparation of the electrophoretic deposition solution requires first weighing 80 mg of hydrophobic modified photothermal conversion material and adding it to a threaded reagent bottle. Then, 100 ml of acetone solution is added, the bottle cap is tightened, and the solution is placed in an ultrasonic machine for one hour of ultrasonic treatment. After treatment, 13.5 mg of iodine is added to the solution, followed by another 3 minutes of ultrasonic treatment. The prepared electrophoretic deposition solution is placed in a pre-customized polytetrafluoroethylene electrophoretic deposition tank. Two crossbeams are installed at the tank opening, with a 1 cm distance between their back faces. The aluminum sheet to be deposited is clamped on one crossbeam and fixed using a negative electrode clamp with an adjustable power supply. A similarly pre-treated but unperforated aluminum sheet is clamped on the other crossbeam as the positive electrode, maintaining a distance of approximately 1 cm from the negative electrode. After deposition begins, a 10V voltage is applied for 5 minutes. After deposition stops, air is blown into the solution using a dropper to agitate and resuspend the precipitated hydrophobic modified photothermal conversion material. This deposition process is repeated three times for a total of 15 minutes to form the photothermal conversion layer. The deposited aluminum sheet is then cut into a predetermined shape.

[0101] Finally, laser surface etching (hydrophilic treatment) is performed again on the bottom surface of the aluminum sheet and the walls of the through holes to complete the preparation of the light absorption layer, which is then used for the subsequent evaporation and salt precipitation process.

[0102] 3. Construction of evaporation devices

[0103] The evaporation device mainly consists of a light-absorbing layer, a water-conducting layer, and a heat-insulating layer. In this embodiment, a 4×4 perforated aluminum sheet deposited with hydrophobic photothermal conversion material is used as the light-absorbing layer. The heat-insulating layer (floating layer) is made of polystyrene foam with heat insulation properties (0.04 W / m / K) and capable of supporting floating, and is cut into hexahedrons with a length, width, and height of 57 mm and 30 mm respectively. To guide the water from the bottom upwards, a water-conducting hole with a diameter of approximately 20 mm is drilled in the center of the square face of the polystyrene foam, penetrating the entire hexahedron. In addition, degreased cotton is selected as the water-conducting material to fill the cavities of the polystyrene foam and is spread between the photothermal layer and the polystyrene foam to form a water-conducting layer. Approximately 1.8 g of degreased cotton is filled in the cavities, and 0.6 g of degreased cotton is filled between the photothermal layer and the polystyrene foam (water-conducting layer).

[0104] Example 2

[0105] Compared with Example 1, except that the diameter of the through hole on the aluminum sheet is 3mm, all other conditions are the same as in Example 1.

[0106] Example 3

[0107] Compared with Example 1, except that the diameter of the through hole on the aluminum sheet is 4mm, all other conditions are the same as in Example 1.

[0108] Comparative Example 1

[0109] Compared with Example 2, except that the bottom surface of the aluminum sheet and the walls of the through holes were not hydrophilic, all other conditions were the same as in Example 2.

[0110] Performance testing

[0111] 1. Evaporation test

[0112] The evaporation devices prepared in Examples 1-3 were tested respectively under the same sunlight (1000W / m²). 2 The evaporation rate under the conditions of ) is tested, and the results are as follows: Figure 3 As shown. By Figure 3 It can be observed that as the aperture of the through-holes on the aluminum sheet increases from 2 mm to 3 mm, the evaporation rate of the device increases significantly, but the evaporation efficiency decreases when the aperture is 4 mm. This indicates that, from an evaporation perspective, a aperture of 3 mm is optimal for the directional salting-out interface evaporation device, and it can achieve stable and sustained water evaporation performance in a solar water evaporation system.

[0113] Furthermore, by recording the quality of the evaporated water, it was found that the evaporation rate of the directional salting-out interface evaporation device steadily increased over time. Under stable light conditions for approximately 3 hours, the evaporation rate of the evaporation device (3mm aperture) reached 0.65 kg / m³. 2 *h, Furthermore, under the same conditions, the evaporation rate of water is 0.36 kg / m³. 2 *h. This shows that the evaporation rate of the evaporation device (3mm aperture) is 1.8 times that of water, indicating that the evaporation device has good evaporation and salt collection performance.

[0114] The evaporation devices prepared in Example 2 and Comparative Example 1 were tested separately under the same sunlight (1000W / m²). 2 The evaporation rate under the conditions of ) is tested, and the results are as follows: Figure 4 As shown. By Figure 4 It can be observed that the evaporation device treated with laser hydrophilicity (Example 2) has a much larger evaporation capacity than the evaporation device without laser treatment (Comparative Example 1) (0.43 kg / m³). 2 *h). This phenomenon is caused by the fact that the more hydrophilic bottom surface is more conducive to the movement of water on its surface, increasing the contact between water and the photothermal conversion layer and the transfer of heat to the aqueous solution, thereby significantly increasing the evaporation rate.

[0115] 2. Salting-out test

[0116] The evaporation devices prepared in Examples 1-3 were tested respectively under the same sunlight (1000W / m²). 2 The salt under the conditions of ) was characterized, and the test results are as follows: Figures 5-10As shown, when the aperture is 2mm, after 60 minutes of testing, the apertures on the evaporation device are basically covered by salt, and the salt precipitation does not change significantly with increasing testing time. However, around the aluminum sheet, after 180 minutes, significant salt precipitation and growth occur compared to the evaporation devices with apertures of 3mm and 4mm. This indicates that when the aperture is 2mm, the small aperture is not conducive to the directional precipitation and growth of salt. Although both 3mm and 4mm apertures show significant directional salt precipitation and growth from the apertures, the evaporation rate of the photothermal conversion layer with a 4mm aperture is less than that with a 3mm aperture. This is because an excessively large aperture reduces the effective photothermal conversion area.

[0117] In summary, the evaporation device and preparation method provided by the present invention, by setting multiple through holes penetrating the top and bottom surfaces of the thermally conductive substrate and performing hydrophilic treatment on the bottom surface of the thermally conductive substrate and the hole walls, allows a hydrophobic photothermal conversion layer to cover the top surface of the thermally conductive substrate. This can significantly improve the evaporation efficiency of the evaporation device and enable the directional precipitation of salt crystals at the through holes, avoiding salt precipitation on the photothermal conversion layer and affecting the photothermal conversion efficiency of the photothermal conversion layer.

[0118] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0119] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An evaporation device, characterized in that, include: A thermally conductive substrate has multiple through holes penetrating its top and bottom surfaces. The bottom surface of the thermally conductive substrate and the walls of the through holes are hydrophilically treated. The thickness of the thermally conductive substrate is 0.5~1mm, the diameter of the through holes is 2~5mm, and the water contact angle between the bottom surface of the thermally conductive substrate and the walls of the through holes after hydrophilic treatment is less than 30°. A hydrophobic photothermal conversion layer covers the top surface of the thermally conductive substrate, and the water contact angle of the hydrophobic photothermal conversion layer is greater than 90°. The bottom surface of the thermally conductive substrate is provided with a water-conducting layer, which is made of a water-conducting material; the bottom surface of the water-conducting layer is provided with a heat insulation layer, which has water-conducting holes penetrating the top and bottom surfaces of the heat insulation layer, and the water-conducting holes are filled with water-conducting filler, which is in contact with the water-conducting layer.

2. The evaporation device according to claim 1, characterized in that, The hydrophobic photothermal conversion layer includes a hydrophobically modified photothermal conversion material, which includes CoNiCuMnAl@C.

3. A method for preparing an evaporation device, used to prepare the evaporation device according to claim 1 or 2, characterized in that, include: A thermally conductive substrate and a photothermal conversion material are prepared. The thermally conductive substrate has multiple through holes penetrating its top and bottom surfaces. The thickness of the thermally conductive substrate is 0.5~1mm, and the diameter of the through holes is 2~5mm. The photothermal conversion material is hydrophobically modified, and the water contact angle of the hydrophobically modified photothermal conversion layer is greater than 90°. The hydrophobically modified photothermal conversion material is deposited on the top surface of the thermally conductive substrate; The bottom surface of the thermally conductive substrate and the walls of the through holes are hydrophilically treated, and the water contact angle between the bottom surface of the thermally conductive substrate and the walls of the through holes after the hydrophilic treatment is less than 30°.

4. The method for preparing the evaporation device according to claim 3, characterized in that, The fabrication methods of thermally conductive substrates include: The top surface of the thermally conductive substrate is scanned with a laser to form a micron-level trench structure on the top surface of the thermally conductive substrate. After the scanning is completed, the thermally conductive substrate is cleaned and dried.

5. The method for preparing the evaporation device according to claim 3, characterized in that, The preparation methods of photothermal conversion materials include: Weigh out cobalt acetate, nickel acetate tetrahydrate, copper acetate monohydrate, and manganese acetate, and add them to N,N-dimethylformamide. Stir well to obtain mixture A. Add terephthalic acid to mixture A and stir vigorously for 1-3 hours to obtain mixture B; The mixture B was centrifuged to obtain a precipitate. The precipitate was washed by centrifugation with N,N-dimethylformamide, and the precipitate was collected and dried under vacuum. The dried precipitate was ground into powder to obtain a high-entropy alloy MOF precursor. The high-entropy alloy MOF precursor material was transferred to a tube furnace. Under the condition of argon-hydrogen mixed gas, the furnace temperature was raised to 680~720℃ at a heating rate of 5℃ per minute. After calcination for 1~2 hours, it was cooled to room temperature to obtain calcined black powder. The calcined black powder was added to a dilute sulfuric acid solution with a concentration of 3-6 mmol / L and ultrasonically dispersed to obtain mixture C; Mixture C was placed in an environment of 60~80℃, and impurities in the black powder were etched by sulfuric acid. After etching, the mixture C was centrifuged to collect the black precipitate, which was then washed and dried to obtain the CoNiCuMnAl@C photothermal conversion material.

6. The method for preparing the evaporation device according to claim 3, characterized in that, The hydrophilic treatment methods for the bottom surface of the thermally conductive substrate and the walls of the through holes include: The bottom surface of the thermally conductive substrate and the walls of the through holes are scanned using a laser.

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