Preparation method and application of a carbon-oxygen-doped carbon nitride-based photothermal heat preservation material

Abstract

This invention relates to the field of optoelectronic materials technology, and discloses a method for preparing and applying a photothermal insulation material based on carbon-oxygen-doped carbon nitride. The preparation method includes mixing melamine and cyanuric acid to form a precursor mixed powder, adding D-glucose and deionized water and mixing evenly to obtain a precursor mixture; transferring it to a tilting homogeneous reactor and reacting it at 160°C for 6-12 h, naturally cooling to room temperature, filtering, washing and drying the filter cake to obtain the doped product; heating to 500-600°C and holding for 2 h to carry out a thermal condensation reaction, naturally cooling to room temperature, pulverizing, and sieving to obtain carbon-oxygen-doped carbon nitride powder.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic materials technology, and specifically relates to a photothermal material, namely a method for preparing and applying a photothermal insulation material based on carbon oxygen doped carbon nitride. Background Technology

[0002] Graphite-like carbon nitride (g-C3N4), as a non-metallic photothermal material, has been widely studied due to its low preparation cost and strong chemical stability. However, traditional carbon nitride can only absorb ultraviolet light with wavelengths less than 420 nm, and its utilization rate of visible light (420-760 nm) and infrared light (>760 nm), which constitute the majority of solar energy, is extremely low, with its photothermal conversion efficiency remaining at only 25%~30%. Expanding the light absorption range of carbon nitride can improve its photothermal conversion efficiency. Existing technologies employ non-metallic element doping techniques; however, doping processes often use stepwise doping, which easily leads to uneven distribution of doped atoms, making it impossible to precisely control the bandgap. Furthermore, the chemical stability and weather resistance of the material decrease after doping, making it difficult to operate stably for long periods in outdoor environments such as low temperatures and strong ultraviolet radiation.

[0003] In addition, in the existing process of combining photothermal materials and insulation materials, high-temperature sintering will destroy the porous insulation structure of foam plastic, or simple physical mixing will cause the photothermal materials to agglomerate and fall off, making it impossible to simultaneously achieve photothermal conversion efficiency and insulation performance.

[0004] In the application of the aforementioned photothermal materials, existing technologies generally employ a design that separates the photothermal and insulation processes. In industrial applications, a layered structure of photothermal collectors and external insulation layers is commonly used. The photothermal materials are typically in powder or film form, attached to the insulation layer and directly laid outdoors or on water surfaces. This separate design has inherent drawbacks: the photothermal materials are susceptible to erosion from rain and snow, and aging due to ultraviolet radiation, leading to rapid performance degradation; furthermore, the powder or film is not firmly bonded to the installation layer. Simultaneously, the separation of the insulation layer and the photothermal layer results in significant heat loss through convection and radiation; traditional vacuum tube solar water heaters experience heat loss rates exceeding 30% in winter, while industrial photothermal heating devices can even exceed 40%.

[0005] In the existing field of industrial wastewater heating, a few have attempted photovoltaic heating technology, but this requires a two-stage energy conversion process of "light-electricity-heat," resulting in energy loss exceeding 20%. However, most wastewater treatment plants still use coal-fired boilers, gas heaters, or electric heating equipment to maintain the temperature of the biological treatment tanks. The winter operating cost of a single plant using coal-fired or gas-fired heating exceeds 100 million yuan, with daily carbon emissions reaching 2,784 tons, causing significant pollution. Furthermore, traditional heating equipment is an external heat source, which cannot be directly adapted to existing biological treatment tanks, making modification difficult. Electric heating equipment is prone to scaling and corrosion, and coal-fired boilers require dedicated personnel for operation, resulting in high maintenance costs.

[0006] Furthermore, in solar concentrators made from photothermal materials, automatic tracking systems rely on photosensitive sensors and precision drive mechanisms, resulting in high costs and high outdoor failure rates. Manual angle adjustment devices lack scientific preset schemes, leading to low concentrating efficiency and difficulty in adapting to the year-round changes in the solar trajectory in northern regions. Meanwhile, civilian applications require lightweight and easy installation, while industrial applications require modularity, stain resistance, and corrosion resistance. Existing technologies struggle to achieve precise adaptation to both scenarios within the same core architecture, often requiring separate designs and incurring high R&D and production costs.

[0007] Therefore, developing a photothermal material and its application scheme that combines broad-spectrum absorption, high weather resistance, low heat loss, and easy integration with thermal insulation materials remains a pressing technical problem to be solved in this field. Summary of the Invention

[0008] To address the problems of existing carbon nitride materials, such as narrow light absorption, uneven doping, poor weather resistance, large heat loss during use, easy material detachment, high operating costs when applied to heating equipment, and inability to be directly adapted, this invention provides a method for preparing and applying a photothermal insulation material based on carbon-oxygen-doped carbon nitride.

[0009] This invention is achieved using the following technical solution: This invention provides a method for preparing a photothermal insulation material based on carbon-oxygen-doped carbon nitride, comprising the following steps: S1, precursor mixture Melamine and cyanuric acid are mixed to form a precursor mixture powder. D-glucose is added as a carbon and oxygen source. The molar ratio of the total molar number of melamine and cyanuric acid to that of D-glucose is 10:(2-8). Deionized water is added and mixed evenly to obtain the precursor mixture.

[0010] For every 1 mol of melamine and 1 mol of cyanuric acid, add 7 L of deionized water. That is, for every 1 mol of melamine and 1 mol of cyanuric acid mixed, add (0.4~1.6) mol of D-glucose and add 7 L of deionized water. To avoid sticking to the wall, the deionized water can be added in multiple batches.

[0011] S2, in-situ doping reaction The precursor mixture obtained in S1 was transferred to a tilting homogeneous reactor. Utilizing its dynamic mixing characteristics, the precursor and dopant source were brought into full contact, achieving uniform in-situ doping of carbon and oxygen atoms in the carbon nitride precursor, thus avoiding the uneven doping problems caused by traditional static hydrothermal processes. The hydrothermal reaction was carried out at 160℃ for 6–12 h to achieve in-situ doping. After the reaction, the mixture was naturally cooled to room temperature, filtered, and the filter cake was washed and dried to obtain the doped product.

[0012] S3, thermal polycondensation reaction The doped product obtained in step S2 is heated to 500-600℃ at a heating rate of 5℃ / min and held at that temperature for 2 hours to carry out a thermal polycondensation reaction.

[0013] S4, Product Purification The product obtained in step S3 was naturally cooled to room temperature, then ground evenly in an agate mortar and passed through a 200-300 mesh sieve to obtain carbon-oxygen doped carbon nitride (CO-CN) powder.

[0014] The present invention also provides a photothermal insulation material based on carbon oxygen doped carbon nitride prepared by the above preparation method.

[0015] In the solar energy spectrum, ultraviolet light (<420nm) accounts for only 5%, visible light (420~760nm) accounts for 45%, and infrared light (>760nm) accounts for 50%. Traditional carbon nitride can only absorb ultraviolet light, resulting in extremely low solar energy utilization. This invention reduces the material's bandgap from 2.7eV to 2.0~2.2eV through non-metallic atom synergistic doping, achieving effective absorption of the entire 200~2500nm spectrum, maximizing the capture of solar energy and its conversion into heat energy.

[0016] This invention also provides the application of the above-mentioned carbon-oxygen-doped carbon nitride-based photothermal insulation material in thermal insulation and heat-concentrating materials. Specifically, the photothermal insulation material based on carbon-oxygen-doped carbon nitride is mixed with a substrate to prepare the insulation material.

[0017] This invention also provides a method for preparing a photothermal functional composite insulation foam using the above-mentioned photothermal insulation material based on carbon oxygen doped carbon nitride, comprising the following steps: S1, Foam substrate pretreatment Take a density of 20~30 kg / m³ 3 Polystyrene foam particles are dried in an oven at 60-80℃ for 2-3 hours to obtain foam substrate; S2, photothermal powder dispersion Carbon-oxygen-doped carbon nitride powder was mixed with ethanol at a mass ratio of 1:(10~15), and 0.5%~1% of polyethylene glycol was added to the total mass of the mixture. The mixture was ultrasonically dispersed for 30~40 min to obtain a uniform powder dispersion. S3, In-situ Loading and Foaming Molding The powder dispersion is mixed evenly with the foam substrate and foamed at 100-120℃ and 0.3-0.5 MPa to form a composite foam preform. The carbon-oxygen doped carbon nitride powder is fixed in the porous skeleton of the foam through physical encapsulation. S4, Cutting The composite foam preform is cooled to room temperature and cut to obtain a photothermal functional composite insulation foam.

[0018] This invention also provides a photothermal functional composite insulation foam prepared using the above-described method. Through integrated foaming and molding, it simultaneously possesses photothermal conversion and heat insulation functions, overcoming the shortcomings of traditional methods that separate the photothermal layer and the insulation layer.

[0019] This invention also provides the application of photothermal functional composite insulation foam in concentrating devices, which can be used as heating modules in solar collectors or biochemical tanks in sewage treatment.

[0020] In traditional solar thermal devices, the solar thermal layer and the insulation layer are separate. Heat is severely lost through convection and radiation during the heat generation, transfer, and storage processes, with a heat loss rate exceeding 30%. Furthermore, the solar thermal material is directly exposed to the environment, making it prone to detachment and aging. The porous framework of the composite foam in this invention provides a stable attachment carrier for the solar thermal powder and, through its closed pore structure, blocks heat convection, achieving heat generation and heat retention simultaneously, thus reducing intermediate losses.

[0021] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for preparing and applying a carbon-oxygen-doped carbon nitride photothermal insulation material. Using thermal polycondensation and in-situ doping, carbon and oxygen atoms are introduced into the carbon nitride lattice, adjusting the bandgap to 2.0–2.2 eV. This expands the light absorption range from less than 420 nm to the full spectrum of 200–2500 nm, increasing the photothermal conversion efficiency from 28.5% to 42.3%. This maximizes the capture of solar energy and its conversion into heat energy. The full-spectrum absorption improves solar energy utilization by more than 1.8 times compared to traditional materials, ensuring efficient heat generation even in low-light conditions during northern winters. The outdoor weather resistance degradation rate decreased from 12.8% to 3.1% after 3 months, demonstrating long-term stable operation under complex environments such as -10℃ low temperatures and rain / snow erosion. This significantly improves the material's stability and service life, providing efficient and stable core material support for photothermal devices.

[0022] The composite foam prepared by this invention based on the above materials achieves deep integration of photothermal and heat insulation functions, breaking through the efficiency bottleneck of traditional devices. During the foaming process, carbon-oxygen-doped carbon nitride powder is firmly fixed in the porous foam skeleton, avoiding damage to the foam insulation structure by high temperature or chemical reagents. The heat loss rate is ≤10%, which is more than 70% lower than the traditional separate design, ensuring that the heat generation efficiency is not ineffectively lost. At the same time, the photothermal powder has zero shedding, and the efficiency decreases by only 0.8% after 24 hours of immersion in sewage, completely solving the problems of easy shedding and poor weather resistance of photothermal materials.

[0023] When applied to devices, the light concentration efficiency is increased by 15%, the light and heat flux reaches 1200 W / m², and the heating rate of wastewater in industrial scenarios is increased from 5℃ / day to 8℃ / day, meeting the need for rapid heating in winter.

[0024] This invention significantly enhances the absorption and thermal energy conversion capabilities of the full solar spectrum; effectively reduces heat loss by controlling heat loss to an extremely low level through an integrated composite foam structure; significantly reduces equipment costs, and can stably generate heat and raise the temperature under sunlight without the need for an external power source or gas; it also possesses excellent adaptability to various scenarios. Therefore, this invention combines significant economic and environmental benefits, saving users substantial operating costs while avoiding energy consumption and carbon emissions. Attached Figure Description

[0025] Figure 1 The images show SEM images of the photothermal materials prepared in Example 1 and Comparative Example 1.

[0026] Figure 2 The figure shows the carbon, nitrogen, and oxygen element distribution of the photothermal materials prepared in Example 1 and Comparative Example 1. In the figure, a is the carbon element distribution of Comparative Example 1, b is the nitrogen element distribution of Comparative Example 1, c is the oxygen element distribution of Comparative Example 1; d is the carbon element distribution of Example 1, e is the nitrogen element distribution of Example 1, and f is the oxygen element distribution of Example 1.

[0027] Figure 3 The images show the UV-Vis diffuse reflectance spectra of Example 1 and Comparative Example 1.

[0028] Figure 4 The images show a comparison of the appearance of Examples 1-4 and Comparative Example 1.

[0029] Figure 5 The images show the photothermal evaluation results of Example 1 and Comparative Example 1.

[0030] Figure 6 The images show the photothermal evaluation results of Examples 1-3. Detailed Implementation

[0031] The specific embodiments of the present invention will be described in detail below. Example 1

[0032] A method for preparing a photothermal insulation material based on carbon-oxygen-doped carbon nitride includes the following steps: S1, precursor mixture Take 0.01 mol of melamine and 0.01 mol of cyanuric acid and mix them to form a precursor mixed powder. Add 0.016 mol of D-glucose as a carbon source and oxygen source, that is, the ratio of precursor mixed powder to D-glucose is 10:8. Add 70 ml of deionized water and mix evenly to obtain the precursor mixture.

[0033] S2, in-situ doping reaction The precursor mixture obtained from S1 was transferred to a tilting homogeneous reactor and subjected to hydrothermal reaction at 160℃ for 12 h to achieve in-situ doping. After the reaction was completed, the mixture was naturally cooled to room temperature, filtered, and the filter cake was washed and dried to obtain the doped product.

[0034] S3, thermal polycondensation reaction The doped product obtained in step S2 was heated to 550°C at a heating rate of 5°C / min and held at that temperature for 2 hours to carry out a thermal polycondensation reaction.

[0035] S4, Product Purification The product obtained in step S3 was naturally cooled to room temperature, then ground evenly in an agate mortar and passed through a 250-mesh sieve to obtain carbon-oxygen doped carbon nitride (CO-CN) powder. Example 2

[0036] A method for preparing a photothermal insulation material based on carbon-oxygen-doped carbon nitride includes the following steps: Except for step S1, where the ratio of precursor mixed powder to D-glucose is 10:6, everything else is exactly the same as in Example 1. Example 3

[0037] A method for preparing a photothermal insulation material based on carbon-oxygen-doped carbon nitride includes the following steps: Except for step S1, where the ratio of precursor mixed powder to D-glucose is 10:4, everything else is exactly the same as in Example 1. Example 4

[0038] A method for preparing a photothermal insulation material based on carbon-oxygen-doped carbon nitride includes the following steps: Except for step S1, where the ratio of precursor mixed powder to D-glucose is 10:2, the rest is exactly the same as in Example 1. Comparative Example 1

[0039] A method for preparing a carbon nitride photothermal material includes the following steps: Except for step S1, in which D-glucose was not added, the rest is exactly the same as in Example 1.

[0040] The prepared carbon-oxygen-doped carbon nitride powder was compared with that of Comparative Example 1. Morphological analysis:

[0041] The morphology of Example 1 and Comparative Example 1 was observed under an electron microscope, such as... Figure 1As shown, the left side is Comparative Example 1, which exhibits an aggregated sheet-like structure. The right side is Example 1. After co-doping modification with C and O, the morphology of Example 1 changed significantly, exhibiting a distinct porous structure and a rougher surface. This is because during the thermal polymerization process, the organic dopant source not only serves as a source of C and O, but also decomposes upon heating to generate gas, promoting the formation of a porous structure in the prepared catalyst.

[0042] Micro-area elemental composition analysis was performed simultaneously on Example 1 and Comparative Example 1, and energy-dispersive X-ray spectroscopy (EDS) characterization was performed, such as... Figure 2 As shown, by adding D-glucose as a dopant, the content of carbon and oxygen elements in Example 1 increased dramatically, and their proportions were significantly higher than those in Comparative Example 1, confirming the successful co-doping of carbon and oxygen elements.

[0043] like Figure 4 As shown, it was observed that the higher the amount of D-glucose added, the darker the color of the product became, indicating that the carbon content of the doped element increased, thus making the color darker. Spectral testing:

[0044] The DRS characterization results were obtained using a UV-3600 ultraviolet-visible-near-infrared spectrophotometer. Figure 3 As shown, Comparative Example 1 showed almost no absorption for light with wavelengths above 420 nm, while Examples 1-4 showed good absorption for light with wavelengths below 800 nm, indicating a significant improvement in the utilization of visible light and extremely strong broad absorption across the entire ultraviolet-visible-near-infrared region. Tests showed that Comparative Example 1 had a light absorption range of 200-420 nm, while Example 1's light absorption range covered 200-2500 nm, completely covering the ultraviolet, visible, and infrared spectrum. Photothermal conversion efficiency test:

[0045] Incandescent lamps were used as the light source to illuminate the sample, and the highest temperature on the sample surface was monitored in real time using a thermal imager.

[0046] Thermal imaging images were acquired for Examples 1, 2, and 3 at irradiation times of 1 minute, 3 minutes, and 5 minutes, respectively. The results are as follows: Figure 6 As shown, with the increase of D-glucose addition, the photothermal temperature rise of the system significantly increased; simultaneously, within the time range of 1–3 min, extending the reaction time also helped to further increase the temperature. This indicates that the doping concentration of D-glucose, i.e., the carbon-oxygen co-doping modification strategy, greatly enhances the photothermal conversion performance of the material. Figure 5As shown, the center temperature of Example 1 can reach 90.3°C after 7 minutes, while the highest temperature of Comparative Example 1 is only 47.7°C, which confirms that the carbon-oxygen doped carbon nitride material of the present invention has a better photothermal conversion capability.

[0047] Simulating AM 1.5G standard sunlight (irradiance 1000 W / m²), with an ambient temperature of 25℃, and using deionized water as the heat transfer medium, the prepared carbon-oxygen-doped carbon nitride powder was directly laid on the surface of the water body. The water temperature change was recorded in real time by a thermometer, and the conversion efficiency was calculated.

[0048] The photothermal conversion efficiency of Comparative Example 1 was measured to be 28.5 ± 1.5%. The photothermal conversion efficiency of Example 1 was 42.3 ± 1.2%.

[0049] In conjunction with Examples 1-4 and Comparative Example 1, Comparative Example 1 exhibits a clear valence band (VB) and conduction band (CB). When a large amount of C and O elements are introduced through doping, dense deep-level defect states are generated in the middle of the bandgap. As the defect concentration increases, these isolated energy levels overlap to form a continuous defect band, causing the material to lose the obvious "bandgap" characteristic of traditional semiconductors and exhibit continuous absorption properties. Weather resistance test:

[0050] In the northern winter outdoor environment, the temperature is -10~5℃, the ultraviolet intensity is 30~50 W / m², the frequency of rain and snow is 2 to 3 times a week, and it is continuously operated for 3 months with regular testing of the weather resistance degradation rate.

[0051] The weathering resistance degradation rate of Comparative Example 1 was 12.8%, while that of Example 1 was 3.1%. Example 5

[0052] A method for preparing a photothermal functional composite thermal insulation foam, wherein the photothermal insulation material based on carbon oxygen doped carbon nitride obtained in Example 1 is used in this embodiment, and the method includes the following steps: S1, Foam substrate pretreatment Take a density of 20~30 kg / m³ 3 Polystyrene foam particles are dried in an oven at 60-80℃ for 2-3 hours to obtain foam substrate; S2, photothermal powder dispersion Carbon-oxygen-doped carbon nitride powder was mixed with ethanol at a mass ratio of 1:(10~15), and 0.5%~1% of polyethylene glycol was added to the total mass of the mixture. The mixture was ultrasonically dispersed for 30~40 min to obtain a uniform powder dispersion. S3, In-situ Loading and Foaming Molding The powder dispersion is mixed evenly with the foam substrate and foamed at 100-120℃ and 0.3-0.5 MPa to form a composite foam preform. The carbon-oxygen doped carbon nitride powder is fixed in the porous skeleton of the foam through physical encapsulation. S4, Cutting The composite foam blank is cooled to room temperature and cut to a preset size. In this embodiment, the thickness is 3cm to obtain a photothermal functional composite insulation foam. Comparative Example 2

[0053] Comparative Example 2 uses pure polystyrene insulation foam of the same specifications as in Example 5, but without loading of carbon-oxygen-doped carbon nitride-based photothermal insulation material. Its specific preparation method is as follows, corresponding to Example 3 but excluding the photothermal powder loading step: S1, Foam substrate pretreatment Take polystyrene foam particles with a density of 20-30 kg / m³ that are exactly the same as those in Example 5 and dry them in an oven at 60-80°C for 2-3 hours to obtain a foam substrate. S2, foam molding The pretreated foam substrate was directly placed under conditions of 100-120℃ and 0.3-0.5 MPa to foam and mold, resulting in a pure polystyrene foam preform (without any photothermal powder loading). S3, Cutting The pure polystyrene foam preform was cooled to room temperature and cut to the same preset size as in Example 5 to obtain the pure polystyrene insulation foam of Comparative Example 2.

[0054] The prepared photothermal functional composite insulation foam was tested. Heat loss rate test:

[0055] The steady-state heat flow method was used, the test environment temperature was -10℃, the inner side of the insulation foam was in contact with 50℃ hot water, and the heat loss rate was measured by a heat flow meter; the heat loss rate of Example 5 was measured to be 8.7±0.5%, while the heat loss rate of Comparative Example 2 was 32.4±2.1%. Adhesion test:

[0056] According to the ASTM D3359 cross-cut test, the cross-cut areas were adhered with 3M tape, and the shedding rate of the photothermal powder was tested. The shedding rate of Comparative Example 2 was 28.3%, while Example 5 did not exhibit delamination, hence the rate was 0%. Water resistance test:

[0057] The composite foam was immersed in simulated wastewater (COD 500 mg / L, pH 7-8) for 24 hours, and the change in photothermal conversion efficiency was tested. The efficiency degradation rate after water resistance in Example 5 was measured to be 0.8%, while the efficiency degradation rate after water resistance in Comparative Example 2 was 15.6%.

[0058] This indicates that Example 5 achieves efficient photothermal conversion while maintaining excellent thermal insulation performance and remaining stable.

[0059] The scope of protection claimed by this invention is not limited to the specific embodiments described above. Moreover, for those skilled in the art, this invention can have various modifications and alterations. Any modifications, improvements, and equivalent substitutions made within the concept and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for preparing a photothermal insulation material based on carbon-oxygen-doped carbon nitride, characterized in that, Includes the following steps S1, precursor mixture Melamine and cyanuric acid are mixed to form a precursor mixture powder. D-glucose is added as a carbon source and oxygen source. The total molar ratio of melamine and cyanuric acid to D-glucose is 10:(2-8). Deionized water is added and mixed evenly to obtain the precursor mixture. S2, in-situ doping reaction The precursor mixture obtained from S1 was transferred to a tilting homogeneous reactor and subjected to hydrothermal reaction at 160℃ for 6-12 h to achieve in-situ doping. After the reaction was completed, the mixture was naturally cooled to room temperature, filtered, and the filter cake was washed and dried to obtain the doped product. S3, thermal polycondensation reaction The doped product obtained in step S2 is heated to 500-600℃ at a heating rate of 5℃ / min and held for 2 hours to carry out thermal polycondensation reaction. S4, Product Purification The product obtained in step S3 was naturally cooled to room temperature, ground evenly, and sieved to obtain carbon-oxygen doped carbon nitride powder.

2. The method for preparing a photothermal insulation material based on carbon-oxygen-doped carbon nitride according to claim 1, characterized in that, In step S1, 7 L of deionized water is added for every 1 mol of melamine and 1 mol of cyanuric acid.

3. A photothermal insulation material based on carbon oxygen doped carbon nitride prepared by the preparation method according to any one of claims 1 or 2.

4. The application of the photothermal insulation material based on carbon-oxygen-doped carbon nitride as described in claim 3, characterized in that, It is used in thermal insulation and heat-concentrating materials.

5. A method for preparing a photothermal functional composite thermal insulation foam, characterized in that, Includes the following steps: S1, Foam substrate pretreatment Take polystyrene foam particles and dry them in an oven at 60-80℃ for 2-3 hours to obtain a foam substrate; S2, photothermal powder dispersion Carbon-oxygen-doped carbon nitride powder was mixed with ethanol at a mass ratio of 1:(10~15), and 0.5%~1% of polyethylene glycol was added to the total mass of the mixture. The mixture was ultrasonically dispersed for 30~40 min to obtain a uniform powder dispersion. S3, In-situ Loading and Foaming Molding The powder dispersion is mixed evenly with the foam substrate and foamed at 100-120℃ and 0.3-0.5 MPa to form a composite foam preform. The carbon-oxygen doped carbon nitride powder is fixed in the porous skeleton of the foam through physical encapsulation. S4, Cutting The composite foam preform is cooled to room temperature and cut to obtain a photothermal functional composite insulation foam.

6. The photothermal functional composite thermal insulation foam prepared by the preparation method described in claim 5.

7. The application of the photothermal functional composite insulating foam according to claim 6 in a solar concentrator, characterized in that, Heating modules used in solar collectors or biochemical tanks in wastewater treatment.

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