Cross-scale gradient co-doped multifunctional composite aerogel as well as preparation method and application thereof

Abstract

The invention relates to the technical field of materials adaptive to extreme environments, and discloses cross-scale gradient co-doped multifunctional composite aerogel as well as a preparation method and application of the cross-scale gradient co-doped multifunctional composite aerogel. The multifunctional composite aerogel is co-doped with ultraviolet light-screening agent nano-particles, infrared light-screening agent nano-particles and functional nano-particles in a cross-scale gradient manner, and is used for performing selective filtration and full-spectrum regulation and control on sunlight penetrating through the transparent aerogel; the ultraviolet light-screening agent particles are titanium dioxide nano particles; the infrared opacifying agent particles are indium tin oxide nanoparticles; and the functional nanoparticles are silver nanorods. The composite aerogel provided by the invention improves the anti-ultraviolet performance and high-temperature heat insulation performance of the aerogel and provides a function of enhancing photosynthesis of plants, and meanwhile, the transmittance of the transparent aerogel in the visible light band of sunlight is not obviously reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of extreme environment adaptable materials, and particularly relates to a cross-scale gradient co-doped multifunctional composite aerogel and a preparation method and application thereof. Background Art

[0002] Building a lunar base is a crucial step in promoting lunar exploration for scientific space environment, searching for signs of life, technological innovation, resource utilization, and expanding human knowledge of space survival. However, due to the extreme environmental conditions on the moon, building a lunar base faces huge technical challenges. For example, the temperature on the moon fluctuates greatly, reaching up to 127 degrees Celsius at the highest and -173 degrees Celsius at the lowest. Heat conduction on the moon is entirely achieved through radiation and conduction, and convection is almost negligible. The impact of thermal radiation varies greatly between the lunar day and night. These extreme temperature changes and heat conduction conditions pose severe challenges to the thermal management of the lunar base. In addition, due to the absence of an atmosphere, the lunar surface is exposed to ultraviolet radiation from the sun, posing a serious threat to the living environment of astronauts.

[0003] In view of the unique challenges brought about by the extreme environmental conditions on the moon, current solutions include the development of advanced thermal insulation materials such as thermosetting resins and glass ceramics, innovative energy storage systems, and thermal protection technologies. Although existing thermal insulation materials can alleviate some thermal management problems on the moon, they still suffer from high thermal conductivity and large weight. For example, the thermal conductivity of thermosetting resin is 0.371 W / m·K, while that of glass ceramics is 0.993 W / m·K, resulting in a large amount of energy loss. In contrast, silica aerogel is well-known for its excellent thermal insulation performance and has attracted much attention in recent years for its application in extreme environments. Silica aerogel has excellent high-temperature resistance, optical transparency, and ultra-light characteristics, so it is very suitable for thermal management and radiation protection applications on the lunar base. In addition, the abundant basalt debris on the lunar surface is rich in silica, providing great support for in-situ manufacturing of aerogels on the moon.

[0004] As a thermal insulation material that is transparent in the sunlight band and has an extremely low thermal conductivity at room temperature, silica aerogel can provide natural lighting for lunar bases and effectively inhibit heat transfer, maintaining a stable temperature inside the lunar bases. However, silica aerogel is almost completely transparent to radiation in the 3-micron to 8-micron band, and high-temperature infrared radiation is mainly in this band. This phenomenon indicates that silica aerogel has weak protection against high-temperature infrared radiation, and the radiative thermal conductivity increases rapidly at high temperatures, greatly reducing the thermal insulation performance. Silica aerogel with a high solar transmittance also has limitations in ultraviolet shielding, making it unable to effectively resist the strong ultraviolet radiation on the lunar surface. For the extreme application scenarios in the lunar environment, it is necessary to dope pure silica aerogel and study the radiation characteristics of the doped composite aerogel to make it have high absorption performance in the ultraviolet and near-infrared parts to shield ultraviolet and infrared light. Existing technologies usually dope light-shielding agent particles into silica aerogel to improve its thermal insulation performance. The doping of light-shielding agents can improve the high-temperature thermal insulation performance, but it will reduce the transmittance in the visible light band of sunlight. In addition, most existing doping schemes are single doping to achieve a single function, and it is difficult to meet the multiple requirements in the extreme environment faced by the sustainable development of lunar bases. Summary of the Invention

[0005] To solve the above problems, the present invention provides a cross-scale gradient co-doped multifunctional composite aerogel, its preparation method and application, which can enhance the ultraviolet resistance performance, high-temperature thermal insulation performance of the aerogel and provide a function to enhance plant photosynthesis through spectral selective regulation.

[0006] To achieve the above object, the technical solution of the present invention is as follows.

[0007] In the first aspect of the present invention, a cross-scale gradient co-doped multifunctional composite aerogel is provided. The multifunctional composite aerogel uses transparent silica aerogel as the matrix, and at least one of ultraviolet light-shielding agent particles, infrared light-shielding agent particles, and functional nanoparticles is doped in the matrix to selectively filter and perform full-spectrum regulation on the sunlight passing through the cross-scale gradient co-doped multifunctional composite aerogel; The ultraviolet light-shielding agent particles are titanium dioxide nanoparticles, the infrared light-shielding agent particles are indium tin oxide nanoparticles, and the functional nanoparticles are silver nanorods.

[0008] In another preferred embodiment, the volume of the titanium dioxide nanoparticles accounts for 0.005% to 0.07% of the volume of the silica aerogel; The particle size of the titanium dioxide nanoparticles is 29.5 nanometers to 31.5 nanometers.

[0009] In another preferred embodiment, the volume of the indium tin oxide nanoparticles accounts for 0.045% to 0.055% of the volume of the silica aerogel; The particle size of the indium tin oxide nanoparticles is 19 nm to 20 nm.

[0010] In another preferred embodiment, the volume of the silver nanorods accounts for 0.001% to 0.002% of the volume of the silica aerogel; The aspect ratio of the silver nanorods is 3.5, and the diameter is 9.5 nm to 10.5 nm.

[0011] The second aspect of the present invention provides a method for preparing the cross-scale gradient co-doped multifunctional composite aerogel, comprising the following steps: Adding at least one of ultraviolet light shielding agent nanoparticles, infrared light shielding agent nanoparticles, and functional nanoparticles to the precursor mixture of the silica aerogel, performing ultrasonic treatment, adjusting the pH of the precursor mixture to 10 to 11, and obtaining a co-doped wet gel after gelation; After aging the co-doped wet gel, performing hydrophobic modification and supercritical drying to obtain the cross-scale gradient co-doped multifunctional composite aerogel; The precursor mixture is obtained by mixing tetramethoxysilane and methanol in a molar ratio of 1:6.4 to 6.42.

[0012] In another preferred embodiment, the ultrasonic treatment is performed at 150 W to 200 W for 30 minutes to 40 minutes.

[0013] In another preferred embodiment, the specific process of the aging is as follows: Soaking the co-doped wet gel in a petri dish mold for 1 day to 2 days, demolding and aging in a glass dish containing ethanol for 5 days to 7 days; The petri dish mold contains a mixed solution of ethanol and methyl orthosilicate with a volume ratio of 1:0.3 to 0.5.

[0014] In another preferred embodiment, after aging the co-doped wet gel, it is soaked in a n-hexane solution for 2 days to 3 days, and then added to a mixed solution of ethanol, trimethylchlorosilane, and n-hexane with a volume ratio of 1:2 to 3:8 to 10 for hydrophobic modification for 2 days to 3 days.

[0015] In another preferred embodiment, the specific process of the supercritical drying is as follows: Placing the hydrophobic modified co-doped wet gel in the extraction kettle of the supercritical drying equipment, setting the temperature of the extraction kettle to 36 °C to 45 °C, pressurizing in a constant flow mode to make the pressure in the extraction kettle reach 8.5 MPa to 9.5 MPa, drying for 4 hours to 5 hours, and then reducing the pressure in the extraction kettle to 0 MPa at a rate of 0.3 MPa to 0.5 MPa per hour to obtain the cross-scale gradient co-doped multifunctional composite aerogel.

[0016] The third aspect of the present invention provides the application of the co-doped multifunctional composite aerogel in the preparation of materials with extreme environment adaptability.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The cross-scale gradient co-doped multifunctional composite aerogel uses transparent silica aerogel as the matrix, and simultaneously doped with ultraviolet light blocking agent nanoparticles, infrared light blocking agent nanoparticles and functional nanoparticles. Through full-spectrum regulation, the cross-scale gradient co-doped multifunctional composite aerogel is used to achieve anti-ultraviolet function, transparent heat insulation function and enhanced plant photosynthesis function to cope with the sustainable development of base construction under the extreme environment of the moon. Due to the electronic transition, high refractive index and local surface plasmon resonance of the ultraviolet light blocking agent nanoparticles, the penetration of ultraviolet light into the material can be effectively reduced by absorption or scattering, thereby improving the anti-ultraviolet performance of the composite aerogel. The infrared light blocking agent nanoparticles have high transmittance in the solar spectrum band, and can effectively absorb infrared thermal radiation based on local surface plasmon resonance to reduce radiative heat loss, thereby providing effective thermal management for the construction of the lunar base. The functional nanoparticles selectively absorb green light based on local surface plasmon resonance to reduce the transmittance of the composite aerogel to the green light spectrum, thereby enhancing plant photosynthesis and providing support for the sustainable construction of the lunar base. The three kinds of nanoparticles have little influence on visible light, and the co-doped composite aerogel can maintain a high solar light transmittance. The composite aerogel prepared by the present invention improves the anti-ultraviolet performance, high-temperature heat insulation performance and provides the function of enhancing plant photosynthesis, while not significantly reducing the transmittance in the solar spectrum band.

[0018] 2. After being modified with trimethylchlorosilane and n-hexane solution in the present invention, methyl replaces hydroxyl, so that the finally obtained composite aerogel has hydrophobic properties, which can effectively solve the problem of functional failure caused by water adsorption during the use of aerogel.

[0019] 3. The present invention uses silica aerogel as the matrix material, which plays a supporting role for the doped nanoparticles. The porous structure of the matrix enhances the propagation distance of sunlight in the composite aerogel, thereby enhancing the capture of specific solar photons. Description of the Drawings

[0020] Figure 1 It is a schematic structural diagram of a cross-scale gradient doped composite aerogel prepared in Example 4 of the present invention.

[0021] Figure 2 It is a scanning electron microscope image of the composite aerogel doped with ultraviolet light blocking agent in Example 1 of the present invention.

[0022] Figure 3 It is a picture taken after the co-doped multifunctional composite aerogel in Example 4 of the present invention is laid flat on the picture.

[0023] Figure 4 This is the spectral transmittance curve graph of the composite aerogel in the embodiment and comparative example of the present invention. Specific embodiments

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0025] In the experimental methods described in the embodiments of the present invention, unless otherwise specified, they are all conventional methods. The materials, reagents, etc. used, unless otherwise specified, can all be obtained from commercial channels.

[0026] For application scenarios in extreme environments such as the moon, it is necessary to dope pure silica aerogel and study the radiation characteristics of the composite aerogel after doping to make it have high absorption performance in the ultraviolet and near-infrared parts. Usually, light-shielding agent particles are doped in pure silica aerogel in a cross-scale gradient to improve its ultraviolet shielding performance and high-temperature heat insulation performance. At the same time, in order to enhance the sustainable construction of the lunar base, a method of adding functional nanoparticles for spectral regulation is adopted. The doping of the two light-shielding agents and functional nanoparticles can improve the anti-ultraviolet performance, high-temperature heat insulation performance and provide the function of enhancing plant photosynthesis, while not significantly reducing the transmittance in the sunlight band.

[0027] Abbreviations of some raw materials used in the present invention: Silicon source tetramethoxysilane: TMOS; Methanol: MeOH; N,N-dimethylformamide: DMF; Ammonium hydroxide: AZAN; Absolute ethanol: EtOH.

[0028] In the following embodiments, titanium dioxide was purchased from Bohuasi Nano Technology (Ningbo) Co., Ltd.; indium tin oxide was purchased from Tianjin Zhujin Technology Development Co., Ltd.; silver nanorods were purchased from Beijing Zhongke Keyou Technology Co., Ltd.

[0029] Example 1 A preparation method of a cross-scale gradient co-doped multifunctional composite aerogel, comprising the following steps: Fully mix silicon source tetramethoxysilane and methanol at a molar ratio of 1:6.42 for 1 hour to obtain a precursor mixture; dissolve 0.042 grams of titanium dioxide particles in 37.3 milliliters of water, ultrasonically disperse for 30 minutes, and then add it to the precursor mixture and mix for 20 minutes; add 34.8 milliliters of 1 molar per liter ammonium hydroxide solution to the precursor mixture to adjust the pH to 10, then pour it into a disposable petri dish and let it stand for 1 minute. After gelation, a co-doped wet gel is obtained.

[0030] Ethanol and methyl orthosilicate aging solution in a volume ratio of 1:0.3 were added to a disposable culture dish mold containing the co-doped wet gel, and the co-doped wet gel was aged for 2 days. After demolding, the aged co-doped wet gel was placed in a glass dish filled with ethanol and aged again for 5 days to obtain an alcohol gel. The alcohol gel was soaked in a n-hexane solution for 2 days, and the alcohol gel was soaked in a mixed solution of ethanol, trimethylchlorosilane and n-hexane in a volume ratio of 1:2:8. After hydrophobic modification for 2 days, the alcohol gel was soaked and replaced with a n-hexane solution for 2 days. The modified co-doped wet gel was supercritically dried and placed in an extraction kettle of a supercritical drying equipment. The temperature of the extraction kettle was set to 45 degrees Celsius, and the pressure in the extraction kettle was pressurized in a constant flow mode to 9.5 MPa and kept dry for 5 hours. The pressure of the extraction kettle was slowly reduced to 0 MPa at a rate of 0.5 MPa per hour to obtain a composite aerogel doped with a UV sunscreen, that is, a cross-scale gradient co-doped multifunctional composite aerogel, and its scanning electron microscope image is as shown in FIG. Figure 2 As shown; Example 2 A method for preparing a cross-scale gradient co-doped multifunctional composite aerogel comprises the following steps: Silicon source tetramethoxysilane and methanol were mixed thoroughly at a molar ratio of 1:6.42 for 1 hour to obtain a precursor mixture. 0.71 g of indium tin oxide particles were dissolved in 37.3 ml of water, ultrasonically dispersed for 30 minutes, and then added to the precursor mixture and mixed for 20 minutes; 34.8 ml of 1 mol / L ammonium hydroxide solution was added to the precursor mixture to adjust the pH to 11, and then poured into a disposable culture dish and allowed to stand for 1 minute to obtain a co-doped wet gel after gelation.

[0031] Add ethanol and methyl orthosilicate aging liquid in a volume ratio of 1:0.5 to a disposable culture dish mold containing co-doped wet gel, age the co-doped wet gel for 1 day, place the aged wet gel in a glass dish filled with ethanol after demoulding and age it again for 7 days to obtain alcohol gel, soak the alcohol gel in a n-hexane solution for 2 days, soak the alcohol gel in a mixed solution of ethanol, trimethylchlorosilane and n-hexane in a volume ratio of 1:2:8, hydrophobic modification for 2 days, and then soak and replace it with a n-hexane solution for 2 days. The modified co-doped wet gel is supercritically dried and placed in an extraction kettle of a supercritical drying equipment, the extraction kettle temperature is set to 36 degrees Celsius, and the pressure in the extraction kettle is pressurized in a constant flow mode to 8.5 MPa and kept dry for 4 hours, and the pressure of the extraction kettle is slowly reduced to 0 MPa at a rate of 0.3 MPa per hour to obtain a composite aerogel doped with an infrared sunscreen agent, that is, a cross-scale gradient co-doped multifunctional composite aerogel.

[0032] Example 3 A method for preparing a cross-scale gradient co-doped multifunctional composite aerogel comprises the following steps: Mix the silicon source tetramethoxysilane and methanol in a molar ratio of 1:6.42 for 1 hour to obtain a precursor mixture. Dissolve 0.02 g of silver nanorods in 37.3 mL of water, add it to the precursor mixture after ultrasonic dispersion for 30 minutes and mix for 20 minutes; add 34.8 mL of 1 mol / L ammonium hydroxide solution to the precursor mixture, adjust the pH to 10, then pour it into a disposable petri dish and let it stand for 1 minute. After gelation, a co-doped wet gel is obtained.

[0033] Add an aging solution of ethanol and tetramethoxysilane with a volume ratio of 1:0.5 to the disposable petri dish mold containing the co-doped wet gel, and age the co-doped wet gel for 1 day. After demolding, place the aged co-doped wet gel in a glass dish filled with ethanol and age it for another 7 days to obtain an alcogel. Soak the alcogel in a n-hexane solution for 2 days, and soak the alcogel with a mixed solution of ethanol, trimethylchlorosilane and n-hexane in a volume ratio of 1:2:8 for hydrophobic modification for 2 days, then soak and displace it with a n-hexane solution for 2 days. The modified wet gel is dried by supercritical drying, placed in the extraction kettle of the supercritical drying equipment, set the temperature of the extraction kettle to 45 °C, pressurize it in a constant flow mode so that the pressure in the extraction kettle is 9.5 MPa and keep it dry for 5 hours, and slowly reduce the pressure of the extraction kettle to 0 MPa at a rate of 0.5 MPa per hour to obtain a composite aerogel doped with functional nanoparticles, that is, a cross-scale gradient co-doped multifunctional composite aerogel.

[0034] Example 4 A preparation method of a cross-scale gradient co-doped multifunctional composite aerogel, comprising the following steps: Mix the silicon source tetramethoxysilane and methanol in a molar ratio of 1:6.42 for 1 hour to obtain a precursor mixture. Dissolve 0.042 g of titanium dioxide particles, 0.71 g of indium tin oxide particles and 0.02 g of silver nanorods in 37.3 mL of water in sequence, add it to the precursor mixture after ultrasonic dispersion for 30 minutes and mix for 20 minutes; add 34.8 mL of 1 mol / L ammonium hydroxide solution to the precursor mixture, adjust the pH to 11, then pour it into a disposable petri dish and let it stand for 1 minute. After gelation, a co-doped wet gel is obtained.

[0035] Add an ethanol and tetramethoxysilane aging solution with a volume ratio of 1:0.3 to a disposable petri dish mold containing the co-doped wet gel, and age the co-doped wet gel for 2 days. After demolding, place the co-doped wet gel in a glass dish filled with ethanol and age it for another 7 days to obtain an alcogel. Immerse the alcogel in a n-hexane solution for 2 days, then immerse the alcogel in a mixed solution of ethanol, trimethylchlorosilane, and n-hexane with a volume ratio of 1:2:8 for hydrophobic modification for 2 days, and then immerse it in a n-hexane solution for soaking and replacement for 2 days. The modified co-doped wet gel is subjected to supercritical drying and placed in the extraction kettle of the supercritical drying equipment. Set the temperature of the extraction kettle to 45 °C, pressurize it in a constant flow mode so that the pressure in the extraction kettle is 8.5 MPa and keep it dry for 5 hours, and slowly reduce the pressure of the extraction kettle to 0 MPa at a rate of 0.5 MPa per hour to obtain a co-doped multifunctional composite aerogel, that is, a cross-scale gradient co-doped multifunctional composite aerogel. Place it on a picture for photographing, and the result is as Figure 3 shown.

[0036] Comparative Example 1 A preparation method of a cross-scale gradient co-doped multifunctional composite aerogel includes the following steps: Fully mix the silicon source tetramethoxysilane and methanol at a molar ratio of 1:6.42 for 1 h, and then add 37.3 mL of water to the mixture; add 34.8 mL of 1 mol / L ammonium hydroxide solution to the mixture to adjust the pH to 10, then pour it into a disposable petri dish and let it stand for 1 minute. After gelation, a wet gel is obtained.

[0037] Add an ethanol and tetramethoxysilane aging solution with a volume ratio of 1:0.3 to a disposable petri dish mold containing the wet gel, and age the wet gel for 2 days. After demolding, place the aged wet gel in a glass dish filled with ethanol and age it for another 5 days to obtain an alcogel. Immerse the alcogel in a n-hexane solution for 2 days, then immerse the alcogel in a mixed solution of ethanol, trimethylchlorosilane, and n-hexane with a volume ratio of 1:2:8 for hydrophobic modification for 2 days, and then immerse it in a n-hexane solution for soaking and replacement for 2 days. The modified wet gel is subjected to supercritical drying and placed in the extraction kettle of the supercritical drying equipment. Set the temperature of the extraction kettle to 45 °C, pressurize it in a constant flow mode so that the pressure in the extraction kettle is 9.5 MPa and keep it dry for 5 hours, and slowly reduce the pressure of the extraction kettle to 0 MPa at a rate of 0.5 MPa per hour to obtain a pure transparent aerogel.

[0038] Comparative Example 2 A preparation method of a cross-scale gradient co-doped multifunctional composite aerogel includes the following steps: Silicon source tetramethoxysilane and methanol were fully mixed at a molar ratio of 1:6.42 for 1 hour to obtain a precursor mixture, 0.042 grams of titanium dioxide particles and 0.02 grams of silver nanorods were dissolved in 37.3 milliliters of water in turn, and the mixture was added to the precursor mixture after ultrasonic dispersion for 30 minutes and mixed for 20 minutes; 34.8 milliliters of 1 mol ammonium hydroxide solution was added to the precursor mixture, the pH was adjusted to 10, and then the mixture was poured into a disposable culture dish and allowed to stand for 1 minute to obtain a co-doped wet gel after gelation.

[0039] Add ethanol and methyl orthosilicate aging liquid in a volume ratio of 1:0.3 to the disposable culture dish mold containing the co-doped wet gel, and age the co-doped wet gel for 2 days. After demoulding, place the aged co-doped wet gel in a glass dish filled with ethanol for another 5 days to obtain an alcohol gel, and soak the alcohol gel in a n-hexane solution for 2 days. Soak the alcohol gel in a mixed solution of ethanol, trimethylchlorosilane and n-hexane in a volume ratio of 1:2:8, hydrophobically modified for 2 days, and then soak and replace it with a n-hexane solution for 2 days. The modified co-doped wet gel is supercritically dried and placed in an extraction kettle of a supercritical drying equipment. The extraction kettle temperature is set to 45 degrees Celsius, and the pressure in the extraction kettle is pressurized in a constant flow mode to 9.5 MPa and kept dry for 5 hours. The pressure of the extraction kettle is slowly reduced to 0 MPa at a rate of 0.5 MPa per hour to obtain a composite aerogel without an infrared sunscreen.

[0040] Table 1 Performance test of composite aerogels prepared in different embodiments and comparative examples As can be seen from Table 1, compared with Examples 1 to 4, the thermal conductivity of Comparative Example 1 at room temperature is 0.0322 W / m·K. The doped nanoparticles affect the microstructure of the aerogel, increase the contact between the particles, and thus affect the transfer of heat flow, while the shielding effect on infrared radiation is not obvious. However, at a high temperature of 400K, since the infrared sunscreen effectively shields infrared radiation, the thermal conductivity of Example 2 is reduced from 0.0394 W / m·K to 0.0385 W / m·K compared with Comparative Example 1, a decrease of 2.3%. Compared with Comparative Example 2, the thermal conductivity of Example 4 is reduced from 0.0439 W / m·K to 0.0409 W / m·K at a high temperature of 400K, a decrease of 6.8%. It shows that Comparative Examples 1 and Comparative Examples 2, which lack infrared sunscreens at high temperatures, have poor thermal insulation properties, which are not conducive to energy saving and heat preservation to cope with the extreme temperature environment of the moon.

[0041] Compared with Examples 1 to 4, the average visible light transmittance of Comparative Example 1 is relatively high, and the maximum ultraviolet transmittance is 29.8%, indicating that although it has good transparency, its ultraviolet shielding performance is very poor and it cannot effectively shield ultraviolet radiation in extreme environments. The introduction of the ultraviolet light blocker reduces the ultraviolet shielding performance of Example 1 and Example 4 by 59.7% and 62.1% respectively compared with Comparative Example 1. At the same time, Examples 1 to 4 still maintain a relatively high sunlight transmittance sufficient to provide ideal natural lighting.

[0042] As Figure 4 shown, compared with Comparative Example 1, Examples 3 and 4 with the introduction of functional nanoparticles have significantly lower transmittance in the green light band, indicating that the examples have better spectral selectivity and can provide the function of enhancing plant photosynthesis.

[0043] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0044] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A cross-scale gradient co-doped multifunctional composite aerogel, characterized in that, The multifunctional composite aerogel uses silica aerogel as the matrix, and at least one of ultraviolet light shielding agent particles, infrared light shielding agent particles, and functional nanoparticles is doped in the matrix to filter and perform full-spectrum regulation on sunlight passing through the cross-scale gradient co-doped multifunctional composite aerogel; The ultraviolet light shielding agent particles are titanium dioxide nanoparticles, the infrared light shielding agent particles are indium tin oxide nanoparticles, and the functional nanoparticles are silver nanorods.

2. The cross-scale gradient co-doped multifunctional composite aerogel according to claim 1, wherein The volume of the titanium dioxide nanoparticles accounts for 0.005% - 0.07% of the volume of the silica aerogel; The particle size of the titanium dioxide nanoparticles is 29.5 nanometers - 31.5 nanometers.

3. The cross-scale gradient co-doped multifunctional composite aerogel according to claim 1, characterized in that, The volume of the indium tin oxide nanoparticles accounts for 0.045% - 0.055% of the volume of the silica aerogel; The particle size of the indium tin oxide nanoparticles is 19 nanometers - 20 nanometers.

4. The cross-scale gradient co-doped multifunctional composite aerogel according to claim 1, characterized in that The volume of the silver nanorods accounts for 0.001% - 0.002% of the volume of the silica aerogel; The aspect ratio of the silver nanorods is 3.5, and the diameter is 9.5 nanometers - 10.5 nanometers.

5. A method for preparing the cross-scale gradient co-doped multifunctional composite aerogel according to any one of claims 1 to 4, characterized in that, It includes the following steps: Add at least one of ultraviolet light shielding agent nanoparticles, infrared light shielding agent nanoparticles, and functional nanoparticles into the precursor mixture solution of silica aerogel, perform ultrasonic treatment, adjust the pH of the precursor mixture solution to 10 - 11, and obtain a co-doped wet gel after gelation; After aging treatment of the co-doped wet gel, perform hydrophobic modification and supercritical drying to obtain the cross-scale gradient co-doped multifunctional composite aerogel; The precursor mixture solution is obtained by mixing tetramethoxysilane and methanol according to a molar ratio of 1:6.4 - 6.

42.

6. The preparation method of the cross-scale gradient co-doped multifunctional composite aerogel according to claim 5, characterized in that, The ultrasonic treatment is carried out at 150 watts - 200 watts for 30 minutes - 40 minutes.

7. The preparation method of the cross-scale gradient co-doped multifunctional composite aerogel according to claim 5, characterized in that, The specific process of the aging is as follows: Immerse the co-doped wet gel in a petri dish mold for 1 day - 2 days, demold it, and age it in a glass dish containing ethanol for 5 days - 7 days; The petri dish mold contains a mixed solution of ethanol and methyl orthosilicate with a volume ratio of 1:0.3 - 0.

5.

8. The preparation method of the cross-scale gradient co-doped multifunctional composite aerogel according to claim 5, characterized in that, The specific process of the hydrophobic modification is as follows: After aging treatment of the co-doped wet gel, immerse it in a n-hexane solution for 2 days - 3 days, add a mixed solution of ethanol, trimethylchlorosilane, and n-hexane with a volume ratio of 1:2 - 3:8 - 10, and perform hydrophobic modification for 2 days - 3 days.

9. The preparation method of the cross-scale gradient co-doped multifunctional composite aerogel according to claim 5, characterized in that, The specific process of the supercritical drying is as follows: Place the hydrophobic modified co-doped wet gel in the extraction kettle of the supercritical drying equipment, set the temperature of the extraction kettle to 36 degrees Celsius - 45 degrees Celsius, pressurize it in a constant flow mode to make the pressure in the extraction kettle reach 8.5 MPa - 9.5 MPa, dry for 4 hours - 5 hours, and then reduce the pressure of the extraction kettle to 0 MPa at a speed of 0.3 MPa - 0.5 MPa per hour to obtain the cross-scale gradient co-doped multifunctional composite aerogel.

10. Application of the cross-scale gradient co-doped multifunctional composite aerogel according to claims 1 - 4 in the preparation of materials for coping with extreme environments.

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