Carbon-based photo-thermal material and preparation method thereof

Abstract

The invention relates to a carbon-based photo-thermal material and a preparation method, and belongs to the technical field of photo-thermal materials. According to the carbon-based photo-thermal material, the petroleum coke-dopamine modified carbonized fiber fabric is selected as a top-layer light absorption material, and visible light, ultraviolet light and near-infrared light in sunlight can be efficiently captured by virtue of the excellent wide-spectrum absorption capacity of petroleum coke, so that the photo-thermal conversion efficiency is greatly improved. The middle-layer water-absorbing fiber fabric rapidly conducts water to the top-layer light-absorbing material by means of the capillary effect, continuous water supply in the evaporation process is guaranteed, efficiency attenuation caused by insufficient water is effectively prevented, and efficient water evaporation operation is guaranteed. The heat insulation layer is made of foam materials, heat generated by the light absorption layer is effectively prevented from being transmitted downwards, the heat is concentrated on an evaporation interface, heat loss is reduced, and the photo-thermal conversion efficiency is further improved.

Description

Technical Field

[0001] The present application relates to the technical field of photothermal materials, and in particular to a carbon-based photothermal material and a preparation method thereof. Background Art

[0002] Traditional distillation, reverse osmosis, and multi-stage flash evaporation technologies all face challenges such as high energy consumption, high costs, and cumbersome processing. In contrast, solar interfacial evaporation technology utilizes clean, renewable solar energy as a power source, which not only helps ensure a secure supply of clean water resources but also effectively reduces environmental pollution, demonstrating enormous potential for application.

[0003] Photothermal materials form the core of solar interfacial evaporation technology. They generate heat by absorbing sunlight energy, thereby driving the evaporation process of seawater. Currently, metal materials, semiconductor materials and carbon-based materials are common types of photothermal materials. However, these materials are often expensive to manufacture and have unsatisfactory photothermal conversion efficiency. Carbon-based photothermal materials are regarded as an ideal and promising photothermal material due to their wide spectral absorption range, low cost and environmental friendliness.

[0004] Given that existing carbon-based photothermal materials mostly use high-cost raw materials such as graphene and carbon nanotubes, there is an urgent need to develop a new method for preparing carbon-based photothermal materials. This method should be able to significantly improve the evaporation rate and photothermal conversion efficiency while maintaining low production costs to achieve wider applications. Summary of the Invention

[0005] The present application provides a carbon-based photothermal material and a preparation method thereof to solve the following technical problem: how to improve the photothermal conversion efficiency of the photothermal material and reduce the cost.

[0006] In a first aspect, an embodiment of the present application provides a carbon-based photothermal material having a Janus structure, wherein the carbon-based photothermal material comprises, from top to bottom, a light-absorbing layer, a water-absorbing layer, and a heat-insulating layer;

[0007] The material of the light-absorbing layer is petroleum coke-dopamine modified carbonized fiber fabric, the material of the water-absorbing layer is water-absorbing fiber fabric, and the material of the heat-insulating layer is foam material.

[0008] Optionally, the thickness ratio of the light absorbing layer to the water absorbing layer is 1 to 3.

[0009] Optionally, the thickness of the heat insulation layer is 0.3 cm to 2 cm, and the thickness of the light absorption layer is 0.5 mm to 5 mm.

[0010] Optionally, the preparation method of the petroleum coke-dopamine modified carbonized fiber fabric includes:

[0011] performing carbonization treatment on the fiber fabric to obtain a carbonized fiber fabric;

[0012] Pretreating the petroleum coke under an inert atmosphere to remove volatile matter from the petroleum coke;

[0013] performing surface oxidation treatment on the pretreated petroleum coke to promote the formation of oxygen-containing functional groups on the surface of the petroleum coke;

[0014] Sequentially dispersing the surface-oxidized petroleum coke and dopamine into a tris-HCl buffer to obtain a precursor solution;

[0015] Immersing the carbonized fiber fabric in the precursor solution, and adding a glutaraldehyde solution dropwise into the precursor solution under stirring at a set temperature to obtain a carbonized fiber fabric containing the precursor;

[0016] The carbonized fiber fabric containing the precursor is washed and dried in sequence to obtain petroleum coke-dopamine modified carbonized fiber fabric.

[0017] Optionally, the temperature of the carbonization treatment is 200° C. to 300° C., the heating rate of the carbonization treatment is 5° C. / min to 10° C. / min, and the time of the carbonization treatment is 1 h to 5 h.

[0018] Optionally, the pretreatment temperature is 200° C. to 500° C., and the inert atmosphere is N 2 or Ar.

[0019] Optionally, the pretreated petroleum coke is subjected to surface oxidation treatment to promote the formation of oxygen-containing functional groups on the surface of the petroleum coke, comprising:

[0020] At a temperature of 20° C. to 60° C., the pretreated petroleum coke is immersed in an oxidant to perform surface oxidation treatment to promote the formation of oxygen-containing functional groups on the surface of the petroleum coke, and then dried; wherein,

[0021] The oxidant is one or more of nitric acid, hydrogen peroxide and sulfuric acid; the concentration of the oxidant is 5% to 20%; and the soaking time is 2 hours to 6 hours.

[0022] Optionally, the mass ratio of the petroleum coke to the dopamine is 0.3-3.

[0023] Optionally, the mass ratio of the dopamine to the glutaraldehyde in the glutaraldehyde solution is 1 to 3.

[0024] Optionally, the stirring at the set temperature includes: stirring at a temperature of 30° C. to 80° C. for 4 h to 8 h.

[0025] Optionally, the drying temperature is 60° C. to 110° C., and the drying time is 12 hours to 24 hours.

[0026] Optionally, the fiber fabric and the water-absorbent fiber fabric both include at least one of the following: absorbent gauze, cotton fabric, linen fabric and wool fabric.

[0027] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0028] The present invention provides a carbon-based photothermal material having a Janus structure. The carbon-based photothermal material comprises, from top to bottom, a light-absorbing layer, a water-absorbing layer, and a heat-insulating layer. The light-absorbing layer is a petroleum coke-dopamine modified carbonized fiber fabric, the water-absorbing layer is a water-absorbing fiber fabric, and the heat-insulating layer is a foam material. The carbonized fiber fabric treated with petroleum coke and dopamine is used as the upper light-absorbing material. Petroleum coke has a broad absorption spectrum, effectively absorbing visible, ultraviolet, and near-infrared light from sunlight. This broad spectrum absorption property enables the material to efficiently absorb light of different wavelengths, thereby improving the photothermal conversion efficiency. The middle layer is a water-absorbing fiber fabric, which not only ensures an adequate water supply but also efficiently transports water to the upper light-absorbing material through capillary action, thereby ensuring the water requirement for the evaporation process and effectively preventing efficiency reduction caused by water loss. The heat-insulating layer prevents the heat generated by the light-absorbing layer from being transferred downward, thereby concentrating the heat at the evaporation interface. Through a carefully designed three-layer structure—a light-absorbing layer, a water-absorbing layer, and a heat-insulating layer—heat is concentrated in the upper layer for evaporation, effectively reducing downward heat conduction and thereby improving the overall light-to-heat conversion efficiency. Furthermore, the use of petroleum coke and fiber fabric as the primary raw materials—both widely available and inexpensive—significantly reduces material costs compared to existing, expensive raw materials like graphene and carbon nanotubes. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0031] Figure 1 A schematic structural diagram of a carbon-based photothermal material provided in an embodiment of the present application;

[0032] In the figure, 1-light absorbing layer, 2-water absorbing layer, 3-heat insulating layer. DETAILED DESCRIPTION

[0033] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0034] The range descriptions described in this article, such as numerical ranges, ratio ranges, etc., include all possible sub-ranges and single numerical values ​​within the range. For example, the range description of "1 to 6" or "1~6" covers all sub-ranges from 1 to 6 (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6). Unless otherwise specified, the terms "including", "comprising", etc. used in this article mean "including but not limited to"; relational terms such as "first" and "second" are only used to distinguish different entities or operations, and do not imply an actual sequence or association relationship; "and / or" means that multiple situations can exist alone or at the same time; expressions such as "at least one", "multiple", and "at least one" refer to any combination of corresponding objects, including a combination of single or multiple objects. The proportional relationships involved in the article, such as mass ratios, molar ratios, etc., should be understood as the corresponding relationship between the first and second terms of the proportional formula in the order of description. The raw materials, reagents, instruments and equipment used in this article can be purchased on the market or prepared by existing methods.

[0035] Figure 1 A schematic structural diagram of a carbon-based photothermal material provided in an embodiment of the present application.

[0036] See Figure 1 In a first aspect, an embodiment of the present application provides a carbon-based photothermal material having a Janus structure, wherein the carbon-based photothermal material comprises, from top to bottom, a light-absorbing layer 1, a water-absorbing layer 2, and a heat-insulating layer 3;

[0037] The light-absorbing layer 1 is a petroleum coke-dopamine modified carbonized fiber fabric, the water-absorbing layer 2 is a water-absorbing fiber fabric, and the heat-insulating layer 3 is a foam material.

[0038] A Janus structure refers to a material or particle with different chemical compositions, physical properties, or functional partitions on either side. In the embodiments of this application, the carbon-based photothermal material has a Janus structure, comprising three layers: a top layer of petroleum coke-dopamine-modified carbonized fiber fabric, responsible for absorbing sunlight; a middle layer of water-absorbing fiber fabric, responsible for transporting moisture; and a bottom layer of foam material, which reduces downward heat conduction. This design enables the material to effectively convert light into heat and transfer moisture, thereby improving the efficiency of solar interfacial evaporation.

[0039] In some embodiments, the ratio of the thickness of the light absorbing layer 1 to the thickness of the water absorbing layer 2 is 1-3.

[0040] Light-absorbing layer 1 absorbs sunlight and converts it into heat, while water-absorbing layer 2 rapidly transports water to light-absorbing layer 1 through capillary action. Controlling the thickness ratio within the range of 1 to 3 ensures that the heat generated by light-absorbing layer 1 is efficiently transferred to the water layer, while the water layer also promptly replenishes the water needed for evaporation, thereby maintaining an efficient photothermal evaporation process. For example, the thickness ratio of the top light-absorbing layer 1 to the middle water-absorbing layer 2 can be 1, 1.5, 2, 2.5, 3, and so on.

[0041] In the embodiment of the present application, the absorbent fiber fabric includes absorbent gauze, cotton fabric, linen fabric and wool fabric, which has good hydrophilicity and can quickly transport water to the upper light-absorbing layer 1 through capillary action to ensure continuous water supply during the evaporation process. This property is crucial for maintaining efficient solar interface evaporation.

[0042] In some embodiments, the thickness of the heat-insulating layer 3 is 0.3 cm to 2 cm, and the thickness of the light-absorbing layer 1 is 0.5 mm to 5 mm.

[0043] The main function of the thermal insulation layer 3 is to prevent the heat generated by the light-absorbing layer 1 from being transferred downward, and to concentrate the heat at the evaporation interface. Controlling the thickness of the thermal insulation layer 3 between 0.3 cm and 2 cm can significantly reduce the loss of heat conducted downward, causing more heat to be concentrated on water evaporation, thereby improving the light-to-heat conversion efficiency. A thermal insulation layer 3 with a thickness greater than 2 cm will increase the volume and weight of the device, which is not conducive to use in the wild or in mobile scenarios; while a thermal insulation layer 3 with a thickness less than 0.3 cm may result in insufficient thermal insulation effect and an inability to effectively maintain a high-temperature environment at the evaporation interface. Therefore, a thickness range of 0.3 cm to 2 cm finds a good balance between performance and practicality. For example, the thickness of the bottom thermal insulation layer 3 can be 0.3 cm, 0.8 cm, 1.3 cm, 1.8 cm, 2 cm, etc.

[0044] The light-absorbing layer 1, as the core component of photothermal conversion, has a thickness that is precisely controlled between 0.5mm and 5mm. This not only ensures sufficient light-absorbing area to capture sunlight, but also effectively prevents the reduction of photothermal conversion efficiency due to excessive thickness. At the same time, the thickness of 0.5mm to 5mm also helps the middle layer of water-absorbing fiber fabric to quickly transport moisture to the light-absorbing layer 1 through capillary action, ensuring sufficient water supply during the evaporation process. Finally, the thickness design of 0.5mm to 5mm also helps to enhance the overall structural stability of the material. The light-absorbing layer 1 with a thickness of less than 0.5mm may not be able to withstand the physical stress during long-term photothermal conversion and water evaporation. For example, the thickness of the top light-absorbing layer 1 can be 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, etc.

[0045] In a second aspect, the present application provides a method for preparing the petroleum coke-dopamine modified carbonized fiber fabric described in the first aspect, the method comprising:

[0046] S1, carbonizing the fiber fabric to obtain a carbonized fiber fabric;

[0047] After carbonization, the fiber fabric forms a carbonized layer with a broad absorption spectrum. This structure can effectively capture visible and near-infrared light from sunlight, thereby improving the efficiency of photothermal conversion. In the embodiments of the present application, the fiber fabric includes absorbent gauze, cotton fabric, linen fabric, and wool fabric.

[0048] In some embodiments, the temperature of the carbonization treatment is 200° C. to 300° C., the heating rate of the carbonization treatment is 5° C. / min to 10° C. / min, and the time of the carbonization treatment is 1 hour to 5 hours.

[0049] Carbonization at a temperature of 200°C to 300°C not only effectively removes non-carbon components from the fiber fabric but also maintains its structural integrity, significantly improving the material's light absorption performance and making it more suitable for use as the light-absorbing layer 1 of a photothermal material. Furthermore, a carbonization temperature of 200°C to 300°C helps prevent excessive graphitization of the material, thereby preserving more surface defects and active sites, further improving the photothermal conversion efficiency. A heating rate of 5°C / min to 10°C / min is designed to ensure uniform heating of the fiber fabric during the carbonization process, preventing cracking or deformation caused by sudden temperature changes. This gradual heating method helps maintain the material's mechanical strength and structural stability, thus meeting the high durability requirements of practical applications. The carbonization time directly affects the degree of carbonization and microstructure of the fiber fabric. Within the range of 1 to 5 hours, as the carbonization time increases, the organic components in the fiber fabric gradually decompose and transform into a stable carbon structure, which helps improve the material's electrical conductivity, mechanical strength, and light absorption capacity. In addition, a carbonization time of 1 to 5 hours can promote the formation of a porous structure in the material, thereby enhancing its hydrophilicity and water absorption capacity, effectively improving its overall performance as a photothermal material. For example, the carbonization temperature can be 200°C, 220°C, 240°C, 260°C, 280°C, 300°C, etc.; the carbonization heating rate can be 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, etc.; the carbonization time can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, etc.

[0050] The selection of the above-mentioned carbonization conditions (temperature, heating rate, and time) not only ensures material performance but also significantly reduces preparation costs. Compared with complex processes requiring high temperature and high pressure, the low-temperature carbonization method used in the embodiments of the present application is more energy-efficient and easy to operate, making it suitable for large-scale production. In addition, fiber fabrics are widely available and inexpensive as raw materials, further enhancing the economy and practicality of this technology.

[0051] S2. pretreating the petroleum coke under an inert atmosphere to remove volatile matter from the petroleum coke;

[0052] In some embodiments, the pretreatment temperature is 200° C. to 500° C., and the inert atmosphere is N 2 or Ar.

[0053] In the examples of the present application, the petroleum coke is crushed and screened to 200-400 mesh before being pretreated under an inert atmosphere. Pretreatment at a temperature range of 200°C to 500°C effectively removes volatile substances from the petroleum coke, thereby improving the stability and purity of the material. Exemplary pretreatment temperatures may include 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, and the like.

[0054] During high-temperature treatment at 200°C to 500°C, the material is prone to react with oxygen in the air, which in turn causes the material's performance to deteriorate or the structure to be damaged. An inert atmosphere (such as nitrogen N2 or argon Ar) can effectively isolate oxygen and prevent materials such as petroleum coke from being oxidized during the pretreatment stage, thereby maintaining the stability of their surface characteristics and chemical properties. Under an inert atmosphere, the material can maintain its original structure and morphology during high-temperature treatment (200°C to 500°C), which is especially important for carbon-based photothermal materials because the structure and morphology of the material directly affect its light absorption and thermal conductivity. By effectively avoiding oxidation reactions, it can be ensured that the material still has excellent photothermal conversion performance after pretreatment. Finally, the use of an inert atmosphere also helps to reduce the by-products and impurities produced by the material during the pretreatment process, thereby improving the purity and stability of the material, which is of great significance for improving the overall performance and service life of carbon-based photothermal materials.

[0055] S3, performing surface oxidation treatment on the pretreated petroleum coke to promote the formation of oxygen-containing functional groups on the surface of the petroleum coke;

[0056] In some embodiments, the pretreated petroleum coke is subjected to surface oxidation treatment to promote the formation of oxygen-containing functional groups on the surface of the petroleum coke, comprising:

[0057] At a temperature of 20° C. to 60° C., the pretreated petroleum coke is immersed in an oxidant to perform surface oxidation treatment to promote the formation of oxygen-containing functional groups on the surface of the petroleum coke, and then dried; wherein,

[0058] The oxidant is one or more of nitric acid, hydrogen peroxide and sulfuric acid; the concentration of the oxidant is 5% to 20%; and the soaking time is 2 hours to 6 hours.

[0059] By soaking petroleum coke in oxidants such as nitric acid, hydrogen peroxide or sulfuric acid at a temperature of 20°C to 60°C, oxygen-containing functional groups (such as hydroxyl, carboxyl, etc.) can be effectively introduced on its surface. These functional groups can significantly improve the hydrophilicity of petroleum coke, thereby enhancing its water absorption efficiency in photothermal materials and its binding force with dopamine (PDA). After surface oxidation treatment, the surface chemical properties of petroleum coke change, making it easier to compound with other materials (such as dopamine) to form a uniform and stable coating. This composite material can better absorb sunlight, broaden the light absorption spectrum range, and thus improve the photothermal conversion efficiency. The surface of the oxidized petroleum coke becomes rougher and increases the active sites, which helps to enhance the mechanical and chemical stability of the material. At the same time, this treatment can also reduce the risk of degradation of the material during long-term use and extend its service life.

[0060] Using nitric acid, hydrogen peroxide, or sulfuric acid as an oxidant is not only low-cost but also simple and suitable for large-scale production. In addition, these oxidants themselves have high environmental compatibility and do not impose a significant burden on the environment.

[0061] S4, sequentially dispersing the surface-oxidized petroleum coke and dopamine into a tris-HCl buffer solution to obtain a precursor solution;

[0062] Tris-HCl solution is a commonly used buffer solution, widely used in biochemistry and molecular biology experiments. Tris (tris(hydroxymethyl)aminomethane) is an organic compound with the chemical formula C4H 11 NO3. When Tris is mixed with hydrochloric acid (HCl), a Tris-HCl buffer is formed, which can effectively maintain the pH value of the solution stable. In the examples of this application, the concentration of the Tris-HCl buffer used is 0.1M and the pH value is 8.5.

[0063] Petroleum coke that has undergone surface oxidation treatment is rich in oxygen-containing functional groups. These functional groups can react chemically with dopamine (PDA) to form a stable composite material. This composite material can significantly improve the absorption capacity of sunlight, thereby enhancing the photothermal conversion efficiency. In tris-HCl buffer, dopamine exhibits excellent self-polymerization ability and can spontaneously form a polydopamine layer. This layer can firmly adhere to the surface of petroleum coke and carbonized fiber fabric. This adhesion not only improves the overall stability of the material, but also enhances its durability. The polydopamine coating itself has good hydrophilicity. By combining it with petroleum coke and fiber fabric, the water absorption properties of the material can be further improved, which is crucial for photothermal materials because good water absorption properties help to continuously supply water, thereby maintaining an efficient photothermal evaporation process.

[0064] In some embodiments, the mass ratio of the petroleum coke to the dopamine is 0.3-3.

[0065] When the mass ratio of petroleum coke to dopamine is in the range of 0.3 to 3, the chemical composition of the material surface and its microstructure can be significantly adjusted. Dopamine, as an efficient functional modifier, can construct a polydopamine layer on the surface of petroleum coke. This layer not only broadens the material's absorption range of sunlight, but also optimizes the hydrophilic properties of the material by introducing a large number of oxygen-containing functional groups, thereby improving the photothermal conversion efficiency. In addition, when the mass ratio is in the range of 0.3 to 3, the combination of petroleum coke and dopamine can form a stable composite structure. The phenolic hydroxyl and amino groups in dopamine can be combined with the oxidized functional groups on the surface of petroleum coke through chemical bonding, thereby enhancing the mechanical stability and chemical durability of the material, which is particularly important for application scenarios where solar evaporators are used for a long time. For example, the mass ratio of petroleum coke and dopamine can be 0.3, 0.8, 1.3, 1.8, 2.3, 2.8, 3, etc.

[0066] S5, immersing the carbonized fiber fabric in the precursor solution, and adding glutaraldehyde solution dropwise to the precursor solution under stirring at a set temperature to obtain a carbonized fiber fabric containing the precursor;

[0067] In some embodiments, the stirring at the set temperature includes stirring at a temperature of 30° C. to 80° C. for 4 to 8 hours.

[0068] By immersing the carbonized fiber fabric in a precursor solution containing petroleum coke and dopamine (PDA), the petroleum coke particles and dopamine can be evenly attached to the surface of the carbonized fiber fabric. In this process, glutaraldehyde, as a cross-linking agent, can react chemically with dopamine to form a stable cross-linked structure, thereby firmly fixing the petroleum coke particles to the surface of the fiber fabric. Through surface functionalization, such as the introduction of nanostructures or specific textures, the light absorption capacity of the material can be significantly enhanced. For example, surface treatment technologies such as plasma treatment and chemical etching, by changing the microstructure and surface energy of the material surface, effectively improve the scattering and absorption of light, thereby improving the light absorption performance of the material. This enhanced light absorption ability enables the material to absorb sunlight more efficiently and convert it into heat energy, thereby improving the photothermal conversion efficiency. In addition, the addition of glutaraldehyde solution not only promotes the adhesion of petroleum coke and dopamine on the carbonized fiber fabric, but also improves the overall mechanical stability of the material through cross-linking. This stability is particularly important for practical applications because during the solar interface evaporation process, the material needs to be exposed to a humid environment for a long time and withstand the erosion of water molecules and physical stress during the evaporation process. Therefore, this operation can effectively prevent petroleum coke particles from falling off the surface of the fiber fabric, thereby extending the service life of the material.

[0069] In some embodiments, the mass ratio of the dopamine to the glutaraldehyde in the glutaraldehyde solution is 1-3.

[0070] Dopamine (PDA) forms a polydopamine layer on the surface of the carbonized fiber fabric during the treatment process, and glutaraldehyde, as a cross-linking agent, can react chemically with dopamine to form a stable cross-linked structure. This cross-linking effect significantly enhances the adhesion of petroleum coke particles to the surface of the carbonized fiber fabric, making it stronger and less likely to fall off. The cross-linking effect of glutaraldehyde significantly enhances the overall mechanical stability of the material. During the solar interface evaporation process, the material needs to be exposed to a humid environment for a long time and withstand the scouring of water molecules and physical stress during the evaporation process. The enhanced stability helps to extend the service life of the material. By adjusting the mass ratio of dopamine to glutaraldehyde, the thickness and uniformity of the surface coating can be precisely controlled, thereby optimizing the light absorption performance of the material. Studies have found that within the mass ratio range of 1 to 3, a coating that is both uniform and has good light absorption capacity can be prepared, which is crucial for improving the photothermal conversion efficiency of the material. For example, the mass ratio of dopamine to glutaraldehyde in the glutaraldehyde solution can be 1, 1.5, 2, 2.5, 3, etc.

[0071] S6, washing and drying the carbonized fiber fabric containing the precursor in sequence to obtain a petroleum coke-dopamine modified carbonized fiber fabric;

[0072] The washing step can effectively remove unreacted substances, by-products or impurities on the surface of the carbonized fiber fabric, such as unbound petroleum coke particles, excess dopamine (PDA) and other residues that may affect the photothermal performance.

[0073] In some embodiments, the drying temperature is 60° C. to 110° C., and the drying time is 12 hours to 24 hours.

[0074] By carrying out a drying treatment within a temperature range of 60°C to 110°C, the moisture in the treated carbonized fiber fabric can be completely evaporated while avoiding damage to the material structure due to excessively high temperatures. The drying time is controlled between 12h and 24h to ensure that the moisture inside the material is completely removed while maintaining stable physical and chemical properties. In addition, the drying process can also promote the complete curing of the glutaraldehyde cross-linking reaction, thereby improving the mechanical strength and durability of the material. For example, the drying temperature can be 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, etc.; the drying time can be 12h, 14h, 16h, 18h, 20h, 22h, 24h, etc.

[0075] The petroleum coke-dopamine modified carbonized fiber fabric, the water-absorbing fiber fabric and the foam material are assembled to obtain a carbon-based photothermal material.

[0076] By using a petroleum coke-dopamine-modified carbonized fiber fabric as the light-absorbing layer 1, this material can achieve broad-spectrum solar light absorption. Petroleum coke has abundant surface functional groups and excellent light absorption capacity, while dopamine treatment further enhances its interfacial bonding and stability. By employing carbon-based micro-nanostructured photothermal materials, such as carbonized potatoes and carbonized sugarcane, and designing a composite solar interface evaporator, the photothermal conversion efficiency is significantly improved. These materials and designs can quickly reach high temperatures under solar irradiation, thereby driving an efficient water evaporation process. The middle layer utilizes a water-absorbing fiber fabric (such as degreased gauze), which can quickly transfer water from the bottom to the light-absorbing layer 1 through capillary action. This structural design ensures an adequate water supply and avoids the loss of evaporation efficiency caused by water shortage. The bottom layer utilizes a foam material with high thermal insulation properties, such as polystyrene foam, polyethylene foam, polyurethane foam, and phenolic foam. The closed-cell structure and foam micropores within these materials effectively reduce the material's thermal conductivity, reducing heat transfer to the bottom, thereby concentrating more heat at the light-absorbing layer 1 and the water evaporation interface. The application of Janus structural design not only greatly improves the overall photothermal conversion efficiency, but also effectively reduces energy loss, thereby achieving a significant increase in evaporation rate.

[0077] Petroleum coke and fiber fabrics have great potential for large-scale production due to their widespread availability, low cost, and simple preparation process (such as carbonization and solution dispersion). Furthermore, by adjusting the thickness of each layer, performance can be further optimized to meet different practical application requirements. This material cleverly utilizes solar energy, a clean energy source, to successfully circumvent the high energy consumption and environmental pollution problems associated with traditional desalination technologies (such as distillation and reverse osmosis). Furthermore, carbon-based materials have minimal environmental impact, aligning with the concept of green and sustainable development.

[0078] In summary, this assembly method fully utilizes the functional characteristics of each layer of material, achieves the synergistic effect of efficient light-to-heat conversion, stable water supply and low heat loss, and provides an economically feasible technical solution to solve the problem of water shortage.

[0079] The present application is further described below with reference to specific examples. Experimental methods in the following examples where specific conditions are not specified are generally measured in accordance with national / industry standards. If there are no corresponding national / industry standards, the methods are carried out in accordance with commonly used international standards, conventional conditions, or conditions recommended by the manufacturer.

[0080] Example 1:

[0081] The degreased gauze was carbonized at 300 ° C for 2 hours to obtain a carbonized fiber fabric. The oxidized petroleum coke was added to the tris-HCl buffer solution, stirred and dispersed evenly, and PDA was added. The mass ratio of petroleum coke to PDA was 1:1. After uniform dispersion, it was stirred in a 50 ° C water bath, and the carbonized fiber fabric was added. Glutaraldehyde solution was slowly added dropwise and stirred for 4 hours. After the reaction was completed, it was washed with deionized water and dried at 60 ° C for 12 hours to obtain the treated carbonized fiber fabric. The treated carbonized fiber fabric, degreased gauze, and polystyrene foam were assembled together to obtain the corresponding carbon-based photothermal material, whose evaporation rate under one sunlight intensity was 1.65 kg·m -2 ·h -1 This rate is higher than the evaporation rate of carbonized potatoes and carbonized sugarcane, but lower than the evaporation rate of the cone-plate structure photothermal interface evaporator. Under the irradiation of a single sunlight, the specific carbon-based photothermal material can quickly heat up to 64.7°C within 1 minute.

[0082] Example 2

[0083] The degreased gauze was carbonized at 280 ° C for 2 hours to obtain a carbonized fiber fabric. The oxidized petroleum coke was added to the tris-HCl buffer solution, stirred and dispersed evenly, and PDA was added. The mass ratio of petroleum coke to PDA was 1:1. After uniform dispersion, it was stirred in a 50 ° C water bath and the carbonized fiber fabric was added. Glutaraldehyde solution was slowly added dropwise and stirred for 4 hours. After the reaction was completed, it was washed with deionized water and dried at 60 ° C for 12 hours to obtain the treated carbonized fiber fabric. The treated carbonized fiber fabric, degreased gauze and polystyrene foam were combined to prepare a carbon-based photothermal material. The evaporation rate of this material under the intensity of one sun reached 1.69 kg·m -2 ·h -1 , compared to the natural evaporation rate of water under dark conditions of 0.16 kg·m -2 ·h -1 At the same time, under the irradiation of one sun, the surface temperature of the carbon-based photothermal material can be raised to 61.7°C in 1 minute.

[0084] Example 3

[0085] The degreased gauze was carbonized at 280 ° C for 2 hours to obtain a carbonized fiber fabric. The oxidized petroleum coke was added to the tris-HCl buffer solution, stirred and dispersed evenly, and PDA was added. The mass ratio of petroleum coke to PDA was 1:2. After uniform dispersion, it was stirred in a 50 ° C water bath and the carbonized fiber fabric was added. Glutaraldehyde solution was slowly added dropwise and stirred for 4 hours. After the reaction was completed, it was washed with deionized water and dried at 60 ° C for 12 hours to obtain the treated carbonized fiber fabric. The treated carbonized fiber fabric, degreased gauze and polystyrene foam were assembled together to obtain the corresponding carbon-based photothermal material, whose evaporation rate under one sunlight intensity was 1.79 kg·m -2 ·h -1 At the same time, under the irradiation of one sun, the surface temperature of the carbon-based photothermal material can be raised to 69.6°C in 1 minute.

[0086] Example 4

[0087] The degreased gauze was carbonized at 280 ° C for 2 hours to obtain a carbonized fiber fabric. The oxidized petroleum coke was added to the tris-HCl buffer solution, stirred and dispersed evenly, and PDA was added. The mass ratio of petroleum coke to PDA was 2:1. After uniform dispersion, it was stirred in a 50 ° C water bath and the carbonized fiber fabric was added. Glutaraldehyde solution was slowly added dropwise and stirred for 4 hours. After the reaction was completed, it was washed with deionized water and dried at 60 ° C for 12 hours to obtain the treated carbonized fiber fabric. The treated carbonized fiber fabric, degreased gauze, and polystyrene foam were assembled together to obtain the corresponding carbon-based photothermal material, whose evaporation rate under one sunlight intensity was 1.75 kg·m -2 ·h -1 At the same time, under the irradiation of one sun, the surface temperature of the carbon-based photothermal material can be raised to 66.2°C in 1 minute.

[0088] Comparative Example 1

[0089] The degreased gauze was carbonized at 280°C for 2 hours to obtain a carbonized fiber fabric. The carbonized fiber fabric, degreased gauze, and polystyrene foam were assembled together to obtain the corresponding carbon-based photothermal material, which had an evaporation rate of 1.50 kg·m under one sunlight intensity. -2 ·h -1 At the same time, under the irradiation of one sun, the surface temperature of the carbon-based photothermal material rose to 54.7°C in 1 minute.

[0090] It can be seen from the examples and comparative examples that the evaporation rate of the carbon-based photothermal material provided in the examples is 1.65 kg·m -2 ·h -1 ~1.79kg·m -2 ·h -1 Compared with the natural evaporation rate of water under dim light (0.16 kg·m-2 ·h -1 Under the irradiation of one sun, the surface temperature of the carbon-based photothermal material provided in the embodiment rose rapidly to 61.7°C to 69.6°C, indicating that it has good photothermal conversion ability.

[0091] One or more technical solutions in the embodiments of the present invention may have at least the following technical effects or advantages:

[0092] The embodiment of the present invention uses petroleum coke and fiber fabric as the main raw materials. These two materials are widely available and inexpensive. Compared with existing expensive raw materials such as graphene and carbon nanotubes, they greatly reduce material costs and are conducive to large-scale production and application.

[0093] The carbon-based photothermal material provided by the embodiments of the present invention has minimal environmental impact and is in line with the concept of green and sustainable development. By utilizing solar energy as a clean energy source, it avoids the high energy consumption and environmental pollution problems of traditional seawater desalination technology.

[0094] The foregoing is merely a detailed description of the present invention, intended to enable those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but rather is intended to conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A carbon-based photothermal material having a Janus structure, comprising from top to bottom: Light-absorbing layer, water-absorbing layer and heat-insulating layer; The material of the light-absorbing layer is petroleum coke-dopamine modified carbonized fiber fabric, the material of the water-absorbing layer is water-absorbing fiber fabric, and the material of the heat-insulating layer is foam material.

2. The carbon-based photothermal material according to claim 1, characterized in that: The thickness ratio of the light absorbing layer to the water absorbing layer is 1-3.

3. The carbon-based photothermal material according to claim 1, characterized in that: The thickness of the heat-insulating layer is 0.3 cm to 2 cm, and the thickness of the light-absorbing layer is 0.5 mm to 5 mm.

4. The carbon-based photothermal material according to claim 1, characterized in that: The preparation method of the petroleum coke-dopamine modified carbonized fiber fabric comprises: performing carbonization treatment on the fiber fabric to obtain a carbonized fiber fabric; Pretreating the petroleum coke under an inert atmosphere to remove volatile matter from the petroleum coke; performing surface oxidation treatment on the pretreated petroleum coke to promote the formation of oxygen-containing functional groups on the surface of the petroleum coke; Sequentially dispersing the surface-oxidized petroleum coke and dopamine into a tris-HCl buffer to obtain a precursor solution; Immersing the carbonized fiber fabric in the precursor solution, and adding a glutaraldehyde solution dropwise into the precursor solution under stirring at a set temperature to obtain a carbonized fiber fabric containing the precursor; The carbonized fiber fabric containing the precursor is washed and dried in sequence to obtain petroleum coke-dopamine modified carbonized fiber fabric.

5. The carbon-based photothermal material according to claim 4, characterized in that: The temperature of the carbonization treatment is 200° C. to 300° C., the heating rate of the carbonization treatment is 5° C. / min to 10° C. / min, and the time of the carbonization treatment is 1 hour to 5 hours.

6. The carbon-based photothermal material according to claim 4, characterized in that: The pretreatment temperature is 200° C. to 500° C., and the inert atmosphere is N 2 or Ar.

7. The carbon-based photothermal material according to claim 4, characterized in that: The process of subjecting the pretreated petroleum coke to surface oxidation treatment to promote the formation of oxygen-containing functional groups on the surface of the petroleum coke comprises: At a temperature of 20° C. to 60° C., the pretreated petroleum coke is immersed in an oxidant to perform surface oxidation treatment to promote the formation of oxygen-containing functional groups on the surface of the petroleum coke, and then dried; wherein, The oxidant is one or more of nitric acid, hydrogen peroxide and sulfuric acid; the concentration of the oxidant is 5% to 20%; and the soaking time is 2 hours to 6 hours.

8. The carbon-based photothermal material according to claim 4, characterized in that: The mass ratio of the petroleum coke to the dopamine is 0.3 to 3; and / or, The mass ratio of the dopamine to the glutaraldehyde in the glutaraldehyde solution is 1 to 3.

9. The carbon-based photothermal material according to claim 4, characterized in that: The stirring at the set temperature includes: stirring at a temperature of 30° C. to 80° C. for 4 to 8 hours; and / or, The drying temperature is 60° C. to 110° C., and the drying time is 12 hours to 24 hours.

10. The carbon-based photothermal material according to claim 1, characterized in that: The fiber fabric and the water-absorbing fiber fabric both include at least one of the following: absorbent gauze, cotton fabric, linen fabric and wool fabric.

Images