WO2020244178A1 - 光热转换材料以及制备光热转换材料的方法 - Google Patents

光热转换材料以及制备光热转换材料的方法 Download PDF

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WO2020244178A1
WO2020244178A1 PCT/CN2019/122615 CN2019122615W WO2020244178A1 WO 2020244178 A1 WO2020244178 A1 WO 2020244178A1 CN 2019122615 W CN2019122615 W CN 2019122615W WO 2020244178 A1 WO2020244178 A1 WO 2020244178A1
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conversion material
photothermal conversion
mass
aerogel
hygroscopic polymer
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PCT/CN2019/122615
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French (fr)
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曲良体
姚厚泽
程虎虎
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清华大学
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • C02F1/14—Treatment of water, waste water, or sewage by heating by distillation or evaporation using solar energy
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/28—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/08—Seawater, e.g. for desalination
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2201/00—Foams characterised by the foaming process
    • C08J2201/04—Foams characterised by the foaming process characterised by the elimination of a liquid or solid component, e.g. precipitation, leaching out, evaporation
    • C08J2201/048—Elimination of a frozen liquid phase
    • C08J2201/0484—Elimination of a frozen liquid phase the liquid phase being aqueous
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2333/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
    • C08J2333/02—Homopolymers or copolymers of acids; Metal or ammonium salts thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C08K3/042—Graphene or derivatives, e.g. graphene oxides
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/20—Controlling water pollution; Waste water treatment
    • Y02A20/208—Off-grid powered water treatment
    • Y02A20/212—Solar-powered wastewater sewage treatment, e.g. spray evaporation

Definitions

  • This application relates to the field of materials, specifically, to photothermal conversion materials and methods for preparing photothermal conversion materials.
  • the water content in the atmosphere is relatively large, and the volume can reach 10% of the total global fresh water. Therefore, the use of water vapor in the atmosphere to obtain fresh water also has a good prospect.
  • the current technology of using solar energy to capture moisture from the air needs to rely on photothermal conversion materials, and the photothermal conversion materials need to meet the following conditions: can absorb a large amount of water vapor from the air spontaneously, in the main energy concentration band of solar energy (250-2500nm) It has high absorption rate, can desorb moisture at a certain high temperature, good mechanical properties, and excellent light-to-heat conversion efficiency.
  • the present invention aims to solve one of the technical problems in the related art at least to a certain extent.
  • the light-to-heat conversion material that uses the water vapor in the atmosphere to obtain desalinated water first needs to have a certain moisture absorption performance.
  • hygroscopic materials such as silica gels, molecular sieves, organometallic frameworks (MOF), etc., have a narrow applicable humidity range, relatively small amount of water captured, and high circulating energy consumption, requiring extra energy from the outside for water vapor desorption. If it is possible to develop a material that can be used in a wide range of humidity and can achieve water vapor desorption without external energy supply, it will greatly improve the efficiency of using water vapor to obtain fresh water.
  • MOF organometallic frameworks
  • a method for obtaining a superabsorbent polymer supported on a three-dimensional graphene aerogel is proposed, which can be mass-produced by a simple solution freeze-drying method.
  • the three-dimensional graphene material not only has a complete skeleton structure with high mechanical properties, but also has a high specific surface area, and is also compatible with polymers. At the same time, it has good absorption in the full spectrum range, and the absorbance can reach more than 95%, which can make full use of solar energy.
  • the three-dimensional graphene aerogel framework can provide a porous structure for the water-absorbing polymer and accelerate the absorption rate of water vapor. And absorption capacity.
  • the present invention provides a photothermal conversion material.
  • the light-to-heat conversion material includes an aerogel matrix, the aerogel matrix includes graphene and a hygroscopic polymer, and the hygroscopic polymer includes a polycarboxyl polymer.
  • the light-to-heat conversion material has the advantages of a wide range of usable humidity, self-desorption of water vapor, and large water vapor adsorption capacity.
  • the hygroscopic polymer includes polyacrylic acid and its salt, alginic acid, polystyrene sulfonic acid and its salt.
  • the water vapor adsorption amount of the photothermal conversion material can be further increased.
  • the ratio of the mass of the hygroscopic polymer to the mass of the graphene is 0.1-1.5.
  • the aerogel matrix can absorb moisture in the air within a full humidity range.
  • the aerogel matrix has a porous structure, and the pore size of the porous structure is 25-60 microns.
  • the saturated water absorption of the photothermal conversion material can reach 5.05 g/g.
  • the absorbance of the photothermal conversion material in the full spectrum range may be higher than 95%.
  • the surface temperature of the photothermal conversion material may be greater than 85 degrees Celsius under the light intensity of 1kW/m 2 .
  • the present invention provides a method for preparing the photothermal conversion material described above.
  • the method includes: mixing graphene oxide and a hygroscopic polymer and freeze-drying to form an aerogel matrix precursor; performing reduction treatment on the aerogel matrix to form an aerogel matrix, and obtaining the photothermal conversion material .
  • the method is simple to operate, easy to expand the production scale, and the obtained photothermal conversion material has at least one of the following advantages: a wide range of usable humidity, self-desorption of water vapor, and a large amount of water vapor adsorption.
  • the graphene oxide solution and the solution containing the hygroscopic polymer are mixed, the concentration of the graphene oxide in the mixed solution is 3-7 mg/ml, and the hygroscopic polymer in the mixed solution
  • the ratio of the mass of the substance to the mass of the graphene oxide is 0.05-0.8. Therefore, it is convenient to form an aerogel precursor by freeze-drying.
  • the mixed solution before performing the freeze-drying, is subjected to vibration mixing and ultrasonic mixing treatment.
  • the freeze-drying treatment is freeze-drying at -30 to -60 degrees Celsius for 30 to 50 hours.
  • the reduction treatment includes: placing the aerogel precursor and the hydrazine hydrate solution in a closed container, heating at 70-100 degrees Celsius, and the heating time is 4-16 hours.
  • an ethanol solution is added to the mixed solution in advance, and the volume ratio of the ethanol solution to the mixed solution is 1:25 ⁇ 1:35.
  • the molding performance of the mixed solution after freeze-drying can be further improved.
  • Figure 1 shows a schematic flow chart of a method for preparing a photothermal conversion according to an example of the present application
  • Figure 2 shows a scanning electron microscope image of the photothermal conversion material according to Example 1 of the present application
  • Fig. 3 shows a scanning electron microscope image of the photothermal conversion material according to Example 1 of the present application
  • Figure 4 shows a full-spectrum light absorption rate curve of the photothermal conversion material according to Example 1 of the present application
  • Figure 5 shows the water absorption of the light-to-heat conversion material according to Example 1 of the present application under different humidity
  • Figure 6 shows the water absorption test results of the photothermal conversion material according to Example 1 of the present application under the full humidity range
  • Figure 7 shows a histogram of saturated water absorption according to some embodiments of the application and comparative examples
  • Fig. 8 shows a digital photograph of the photothermal conversion material according to Comparative Example 4 of the present application.
  • the present invention provides a photothermal conversion material.
  • the photothermal conversion material includes an aerogel matrix, and the aerogel matrix includes graphene and a hygroscopic polymer.
  • the light-to-heat conversion material has the advantages of a wide range of usable humidity, self-desorption of water vapor, and large water vapor adsorption capacity.
  • Some current light-to-heat conversion materials have problems such as poor water vapor absorption performance, or difficulty in independent molding, requiring additional loading on a substrate with better mechanical properties.
  • carbon nanomaterials such as graphene have good thermal conductivity, and have good light absorption properties in the full spectrum range, they have strong mechanical properties and are suitable for It is used to prepare light-to-heat conversion materials, but its water absorption performance is not ideal, and the efficiency of absorbing water vapor from the air is not high.
  • hygroscopic polymer materials such as silica gels, molecular sieves, organometallic frameworks (MOF), etc.
  • MOF organometallic frameworks
  • the above-mentioned hygroscopic polymer material has the problem of poor mechanical strength of the material, it is difficult to form a reliable self-supporting block structure, and it needs to be loaded on other substrates for molding. Therefore, if a gel can be provided that has the advantages of graphene materials and hygroscopic polymers, the water production and water production efficiency of the photothermal conversion material can be greatly improved.
  • the present invention proposes an aerogel including graphene and a hygroscopic polymer. Since the aerogel matrix has graphene and hygroscopic polymers, it has both the relatively excellent light-to-heat conversion performance of carbon nanomaterials and the ability of hygroscopic polymers to absorb water vapor. In addition, in the light-to-heat conversion material according to the embodiment of the present invention, the aerogel matrix has good mechanical properties, can be self-supported into blocks, and can form larger blocks without being loaded on other substrates, which can be used directly Used in seawater desalination or water purification technology based on steam.
  • the specific material of the hygroscopic polymer in the aerogel matrix is not particularly limited, as long as it has good hygroscopic properties and has a certain compatibility with graphene.
  • a multi-hydrophilic group polymer can be used to form the hygroscopic polymer in the aerogel matrix.
  • the term "multi-hydrophilic group polymer" specifically refers to a material that includes a hydrophilic group in the polymer monomer, for example, the monomer may include at least one of a carboxyl group, a hydroxyl group, and a sulfonic acid group.
  • the hygroscopic polymer may include polyacrylic acid and its salt, alginic acid and its salt, polystyrene sulfonic acid and its salt.
  • polyacrylic acid and its salt alginic acid and its salt
  • polystyrene sulfonic acid and its salt sodium polyacrylate (hereinafter referred to as PAAS) has good water absorption performance, and can be better integrated with the skeleton structure of graphene aerogel, thereby further increasing the water vapor adsorption capacity of the photothermal conversion material. At the same time, it is ensured that the aerogel matrix can maintain a complete block structure.
  • PAAS sodium polyacrylate
  • the quality of the hygroscopic polymer in the aerogel matrix and the quality of graphene are not particularly limited, as long as it does not affect the molding of the aerogel matrix and can maintain the mass after absorbing water vapor.
  • the integrity of the body is sufficient.
  • the ratio of the mass of the polymer in the aerogel matrix to the mass of the graphene may be 0.1-1.5. More specifically, the aerogel matrix may be formed by mixing a hygroscopic polymer and a graphene oxide solution, and then undergoing a molding treatment and a reduction treatment.
  • the ratio of the mass of hygroscopic polymer to the mass of graphene oxide can be 0.01-0.8, for example, it can be 10%, 15%, 20%, 25%, 40% , 60%, etc.
  • Graphene oxide is reduced to graphene after reduction treatment, and the process does not affect the formation of graphene oxide and hygroscopic polymer aerogel block. After the reduction treatment of graphene oxide aerogel, the aerogel matrix It can still maintain a good block structure and has certain mechanical properties. After many times of water vapor absorption and desorption, the block has no significant fragmentation, slag drop, etc.
  • the ratio of the mass of polyacrylate to the mass of graphene in the light-to-heat conversion material may be 0.25 to 0.65.
  • the aerogel matrix has both the good light-to-heat conversion performance of graphene and the moisture absorption performance of hygroscopic polymers (such as PAAS, sodium polyacrylate), the light-to-heat conversion material can be used in full humidity. Absorb moisture in the air within the range.
  • the aerogel matrix has a porous structure, and the pore size of the porous structure is 25-60 microns.
  • the aerogel with the pore size in the above range can ensure a larger comparison area on the one hand, thereby increasing the water absorption of the photothermal conversion material, and on the other hand, can also ensure the mechanical properties of the aerogel matrix.
  • the saturated water absorption capacity of the photothermal conversion material according to the embodiment of the present invention can reach 5.05 g/g.
  • the photothermal conversion material may further include metal catalyst particles, for example, it may include metal or metal oxide catalyst particles.
  • the porous structure of the aerogel matrix can provide a good supporting matrix for the catalyst particles, and the graphene aerogel can also easily integrate the metal catalyst particles in the aerogel by adding metal salts during the hydrothermal forming process. On the gum base.
  • the absorbance of the above-mentioned photothermal conversion material in the full spectrum range may be higher than 95%.
  • the photothermal conversion material has good photothermal conversion efficiency, and can convert most of the light energy in sunlight into heat energy.
  • the surface temperature of the photothermal conversion material can be greater than 85 degrees Celsius under the light intensity of 1kW/m 2 . That is to say, because the photothermal conversion material has good photothermal conversion efficiency, the water vapor (condensed into liquid water) that is spontaneously adsorbed inside the photothermal conversion material can be spontaneously evaporated and separated on the surface of the material, causing autonomous desorption Attached, so that the recovery of purified water (steam) can be realized without additional energy supply.
  • the components of the photothermal conversion material are simple, the preparation method is not particularly limited, and the production scale can be simply expanded.
  • the ideal ratio of graphene and hygroscopic polymer can not only ensure that the light-to-heat conversion material can have better light-to-heat conversion efficiency and water production, but also that the component is expanding production (that is, expanding the aerogel matrix prepared in a single time). It can also ensure that the large aerogel matrix can also be formed well, thereby eliminating the need to provide an additional matrix and load the photothermal conversion material.
  • the present invention provides a method for preparing the photothermal conversion material described above. Specifically, referring to FIG. 1, the method includes:
  • the graphene oxide and the hygroscopic polymer are first mixed and lyophilized to form an aerogel matrix precursor.
  • the graphene oxide solution and the solution containing the hygroscopic polymer may be mixed.
  • the mixed solution can be a graphene oxide solution and an aqueous solution of sodium polyacrylate.
  • the mixing can be achieved by using a vortex oscillator to vigorously vibrate, so that the graphene oxide and sodium polyacrylate are uniformly mixed in the mixed solution, and can be supplemented by ultrasonic treatment, for example, after vortexing. Carry out ultrasonic treatment for about 10 minutes.
  • the specific content of graphene oxide and sodium polyacrylate in the mixed solution is not particularly limited, as long as the ratio of the mass of the polymer in the aerogel matrix to the mass of the graphene can be adjusted after the subsequent reduction.
  • the range of 0.05 to 0.8 is sufficient.
  • a graphene oxide solution of 10-20 mg/ml can be selected, mixed with sodium polyacrylate aqueous solution, and an appropriate amount of deionized water is added to make the final concentration of graphene oxide in the mixed solution 3-7 mg/ml.
  • the ratio of the mass of PAAS to the mass of graphene oxide in the solution may be 0.01 to 0.35, for example, it may be 10%, 15%, 20%, 25%, 40%, 60%, and so on. Therefore, it is convenient to form an aerogel precursor by freeze-drying.
  • the freeze-drying treatment may be performed at -30 to -60 degrees Celsius, and the freeze-drying time may be 30-50 hours.
  • the above solution can be poured into any mold, frozen on the surface of liquid nitrogen, that is, surface freezing is performed using liquid nitrogen, and then dried with a freeze dryer at -50°C for 48 hours.
  • an ethanol solution may be added to the mixed solution in advance before lyophilizing the mixed solution.
  • the volume ratio of the ethanol solution and the mixed solution may be (1:25) to (1:35), for example, it may be 1:30.
  • the molding performance of the mixed solution after freeze-drying can be further improved.
  • the inventor found that the addition of ethanol can reduce the surface tension of the mixed solution, and prevent the uneven formation of ice crystals during the freezing process and cause the sample to break.
  • the photothermal conversion material may further include metal catalyst particles, for example, it may include metal or metal oxide catalyst particles.
  • the porous structure of the aerogel matrix can provide a good supporting matrix for the catalyst particles.
  • a metal salt solution or metal particles can be added to the mixed solution before freeze-drying and mixed, and then the metal particles can be composited on the aerogel matrix during the freeze-drying process.
  • a process including but not limited to solvothermal can also be used to convert the metal salt solution into metal oxides and other particles that have photothermal conversion or improve thermal conductivity, thereby acting as a metal catalyst and supporting the aerogel matrix.
  • the aerogel precursor is subjected to reduction treatment to form an aerogel matrix, and the photothermal conversion material is obtained.
  • the method is simple to operate, easy to expand the production scale, and the obtained photothermal conversion material has at least one of the following advantages: a wide range of usable humidity, self-desorption of water vapor, and a large amount of water vapor adsorption.
  • the reduction treatment may include: placing the aerogel precursor and the hydrazine hydrate solution in a closed container to reduce graphene oxide in the aerogel precursor to graphene.
  • the reduction treatment may be heating at 70-100 degrees Celsius, and the heating time is 4-16 hours.
  • the graphene oxide in the aerogel precursor can be easily reduced to graphene.
  • Example 2 The remaining steps are the same as in Example 1, except that when the freeze-dried mixed solution is formed, a solution with a PAAS/GO mass ratio of 1:10 is obtained.
  • the ratio of the mass of PAAS to the mass of graphene in the aerogel matrix is 0.2.
  • Example 2 The remaining steps are the same as in Example 1, except that when the freeze-dried mixed solution is formed, a solution with a PAAS/GO mass ratio of 1:7 is obtained.
  • the ratio of the mass of PAAS to the mass of graphene in the aerogel matrix is 0.28.
  • Example 2 The remaining steps are the same as in Example 1, except that when the freeze-dried mixed solution is formed, a solution with a PAAS/GO mass ratio of 1:5 is obtained.
  • the ratio of the mass of PAAS to the mass of graphene in the aerogel matrix is 0.4.
  • Example 2 The rest of the steps are the same as in Example 1, except that when the freeze-dried mixed solution is formed, a solution with a PAAS/GO mass ratio of 1:3 is obtained.
  • the ratio of the mass of PAAS to the mass of graphene in the aerogel matrix is 0.67.
  • Example 2 The remaining steps are the same as in Example 1, except that sodium alginate is used as a hygroscopic polymer, and when a freeze-dried mixed solution is formed, a solution with a mass ratio of alginic acid:GO of 1:4 is obtained.
  • the ratio of the mass of alginic acid to the mass of graphene in the aerogel matrix is 0.5.
  • Example 2 The remaining steps are the same as in Example 1, except that sodium alginate is used as a hygroscopic polymer, and when a freeze-dried mixed solution is formed, a solution with a sodium alginate:GO mass ratio of 1:7 is obtained.
  • the ratio of the mass of alginic acid to the mass of graphene in the aerogel matrix is 0.28.
  • Example 2 The remaining steps are the same as in Example 1, except that polystyrene sulfonic acid is used as the hygroscopic polymer, and when the freeze-dried mixed solution is formed, a solution with a polystyrene sulfonic acid:GO mass ratio of 1:5 is obtained.
  • the ratio of the mass of polystyrene sulfonic acid to the mass of graphene in the aerogel matrix is 0.4.
  • Example 2 The rest of the steps are the same as in Example 1. The difference is that sodium polystyrene sulfonate is used as the hygroscopic polymer.
  • sodium polystyrene sulfonate is used as the hygroscopic polymer.
  • the configuration obtains the sodium polystyrene sulfonate:GO mass ratio of 1:5. Solution.
  • the ratio of the mass of sodium polystyrene sulfonate to the mass of graphene in the aerogel matrix is 0.4.
  • Example 2 The remaining steps are the same as in Example 1, except that when the freeze-dried mixed solution is formed, a solution with a PAAS/GO mass ratio of 0.35/1 is obtained.
  • the ratio of the mass of PAAS and the mass of graphene in the aerogel matrix is 0.7.
  • Example 2 The rest of the steps are the same as in Example 1, except that when the freeze-dried mixed solution is formed, a solution with a PAAS/GO mass ratio of 1:20 is obtained.
  • the ratio of the mass of PAAS to the mass of graphene in the aerogel matrix is 0.1.
  • Example 2 The remaining steps are the same as in Example 1, except that no ethanol solution is added before freeze-drying.
  • the aerogel material was characterized by scanning electron microscopy (SEM). Examples 1-9 all have similar morphologies. Taking Example 1 as an example, referring to Fig. 2 and Fig. 3, from the SEM of the upper surface of the sample, it can be seen that the photothermal conversion material has a porous structure with a pore size distribution of 30-50 microns.
  • Examples 1-9 were tested for the absorption rate of sunlight in the full spectrum range (250-2500 nm) and the moisture absorption effect in the full humidity range. Examples 1-9 all have good light absorption capacity and water absorption rate. Taking the test result of Example 1 as an example, referring to Figure 4, the light absorption rate of the photothermal conversion material is 95%, and it has a good absorption of sunlight, while the bulk material of the same volume prepared by pure PAAS basically does not have Absorbing ability.
  • the photothermal conversion material obtained in Example 1 has a good water vapor absorption effect and a faster rate in the full humidity range, and referring to Fig. 6, the photothermal conversion material can have a water absorption as high as 5.05g/g, That is: 1g of light-to-heat conversion material can absorb water with a mass of more than 5 times.

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Abstract

公开了一种光热转换材料及其制备方法。该光热转换材料包括：气凝胶基体，所述气凝胶基体包括石墨烯以及吸湿聚合物。

Description

光热转换材料以及制备光热转换材料的方法 技术领域
本申请涉及材料领域，具体地，涉及光热转换材料以及制备光热转换材料的方法。
背景技术
随着全球水资源的短缺，废水利用技术受到了较为广泛的关注。例如膜蒸馏、反渗透、电渗析、超过滤、太阳能水蒸发等技术，均可将不可用废水转换为可用淡水资源，以此解决水资源短缺问题。考虑到经济成本，无需耗能的太阳能水蒸发越来越受到关注。尽管随着海水淡化技术的发展，基于海水的水处理技术已经形成了丰富的体系，但多数水处理技术仍旧是基于对液态水的水质进行处理，例如，利用反渗透、电渗析、超过滤等技术，将液态的海水转换成淡化水，或是基于膜蒸馏、太阳能水蒸发等技术，将液态海水转换为蒸汽，再凝结为淡水。其中，利用太阳能蒸发海水进行海水淡化的技术中，多依靠光热转换材料，提高海水的光热转换效率。
根据海陆间的水循环图，大气中含水量较大，体量可达全球淡水总量的10％。因此利用大气中的水蒸汽获得淡水也具有较好的前景。目前利用太阳能从空气中捕获水分的技术需要依靠光热转换材料进行，且光热转换材料需要满足以下条件：能够从空气中自发地吸收大量水汽、在太阳能主要的能量集中波段(250–2500nm)具有高的吸收率、在一定的高温下能够解吸附水气、良好的机械性能、优异的光热转换效率等。
然而，目前的光热转换材料以及其制备方法仍有待改进。
发明内容
本发明旨在至少在一定程度上解决相关技术中的技术问题之一。
如前所述，利用大气中的水蒸汽获取淡化水的光热转换材料首先需要具有一定的吸湿性能。而吸湿性材料例如硅胶类、分子筛类、有机金属框架(MOF)等的适用湿度范围较窄，捕获的水量相对较少，循环耗能大，需要外界给予额外的能量用于水汽的脱附。如能够开发一种在较宽的湿度范围内均可使用，且无需外接能量供给即可实现水汽脱附的材料，将大幅提高利用水蒸汽获取淡水的效率。
有鉴于此，在本申请的一个方面，提出了一种获得高吸水性高分子聚合物负载在三维石墨烯气凝胶上的方法，通过简单的溶液冷冻干燥法可以大规模生产。三维的石墨烯材料不但具备完整的高机械性能骨架结构，也具有高比表面积，与高分子的兼容性也较好。同时，在全光谱范围内有良好的吸收，吸光度可以达到95％以上，可以充分利用太阳能，同时，三维石墨烯气凝胶骨架可为吸水性高分子提供多孔结构，加快了水蒸汽的吸收速率和吸收 容量。
在本发明的一个方面，本发明提出了一种光热转换材料。该光热转换材料包括：气凝胶基体，所述气凝胶基体包括石墨烯以及吸湿聚合物，所述吸湿聚合物包括多羧基聚合物。该光热转换材料具有可用湿度范围较宽、水汽可自主脱附、水汽吸附量大等优点。
根据本发明的实施例，所述吸湿聚合物包括聚丙烯酸及其盐、海藻酸、聚苯乙烯磺酸及其盐。由此，可进一步提高该光热转换材料的水汽吸附量。
根据本发明的实施例，所述气凝胶基体中，所述吸湿聚合物的质量以及所述石墨烯的质量之比为0.1-1.5。
根据本发明的实施例，所述气凝胶基体可在全湿度范围内吸收空气中的水分。
根据本发明的实施例，所述气凝胶基体具有多孔结构，所述多孔结构的孔径为25～60微米。
根据本发明的实施例，所述光热转换材料的饱和吸水量可达到5.05g/g。
根据本发明的实施例，所述光热转换材料在全光谱范围内的吸光度可高于95％。
根据本发明的实施例，在1kW/m 2的光强照射下，所述光热转换材料的表面温度可大于85摄氏度。
在本发明的另一方面，本发明提出了一种制备前面描述的光热转换材料的方法。该方法包括：将氧化石墨烯以及吸湿聚合物混合并冻干形成气凝胶基体前驱体；对所述气凝胶基体进行还原处理，以形成气凝胶基体，并获得所述光热转换材料。该方法操作简单，便于扩大生产规模，且获得的光热转换材料至少具有以下优点的至少之一：可用湿度范围较宽、水汽可自主脱附、水汽吸附量大等。
根据本发明的实施例，将氧化石墨烯溶液以及含有所述吸湿聚合物的溶液进行混合，混合溶液中所述氧化石墨烯的浓度为3－7mg/ml，所述混合溶液中所述吸湿聚合物的质量和所述氧化石墨烯质量的比为0.05～0.8。由此，便于利用冻干形成气凝胶前驱体。
根据本发明的实施例，在进行所述冻干之前，对所述混合溶液进行震荡混合以及超声混合处理。
根据本发明的实施例，所述冻干处理是在－30～－60摄氏度下冻干30～50小时。
根据本发明的实施例，所述还原处理包括：将所述气凝胶前驱体以及水合肼溶液置于密闭容器中，加热70－100摄氏度，加热时间为4－16小时。
根据本发明的实施例，将所述氧化石墨烯以及所述吸湿聚合物进行混合之后，进行冻干之前，预先在混合溶液中加入乙醇溶液，所述乙醇溶液和所述混合溶液的体积比为1：25～1：35。由此，可进一步提高混合溶液冻干后的成型性能。
附图说明
图1显示了根据本申请一个示例的制备光热转换方法的流程示意图；
图2显示了根据本申请实施例1的光热转换材料的扫描电子显微镜图；
图3显示了根据本申请实施例1的光热转换材料的扫描电子显微镜图；
图4显示了根据本申请实施例1的光热转换材料的全光谱光线吸收率曲线；
图5显示了根据本申请实施例1的光热转换材料在不同湿度下的吸水量；
图6显示了根据本申请实施例1的光热转换材料在全湿度范围下的吸水量测试结果；
图7显示了根据本申请一些实施例以及对比例的饱和吸水量的柱状图；
图8显示了根据本申请对比例4的光热转换材料的数码照片图。
具体实施方式
下面详细描述本发明的实施例，所述实施例的示例在附图中示出，其中自始至终相同或类似的标号表示相同或类似的元件或具有相同或类似功能的元件。下面通过参考附图描述的实施例是示例性的，仅用于解释本发明，而不能理解为对本发明的限制。
在本发明的一个方面，本发明提出了一种光热转换材料。该光热转换材料包括气凝胶基体，该气凝胶基体包括石墨烯以及吸湿聚合物。该光热转换材料具有可用湿度范围较宽、水汽可自主脱附、水汽吸附量大等优点。
为了便于理解，下面首先对根据本发明实施例的光热转换材料可实现上述有益效果的原理进行简单说明：
目前的一些光热转换材料，存在水蒸汽吸收性能较差，或是难以独立成型需要额外负载在机械性能较好的基体上等问题。具体地，针对基于碳纳米材料的光热转换材料而言，虽然石墨烯等碳纳米材料具有较好的导热性，且在全光谱范围内均具有较好的吸光性能，机械性能较强，适于制备光热转换材料，但其吸水性能并不够理想，从空气中吸收水蒸汽的效率不高。而常用的吸湿性高分子材料，例如硅胶类、分子筛类、有机金属框架(MOF)等材料，虽然具有较好的吸湿性能但不具有光热转换性能因此需要外部供给能量实现水汽的脱附。或者上述吸湿性高分子材料存在材料机械强度较差，难以形成可靠的自支撑的块体结构，需要负载在其他基体上成型的问题。因此，如能够提供一种凝胶，兼具石墨烯材料以及吸湿高分子的优点，则可大幅提高光热转换材料的产水量以及产水效率。
有鉴于此，本发明提出了一种包括石墨烯以及吸湿聚合物的气凝胶。该气凝胶基体由于具有石墨烯以及吸湿聚合物，因此兼具碳纳米材料较为优良的光热转换性能，以及吸湿聚合物的吸收水汽的能力。并且，根据本发明实施例的光热转换材料中，气凝胶基体具有较好的机械性能，可自支撑成块，无需负载在其它基体上即可形成体积较大的块体，可直 接用于海水淡化或是基于水蒸汽的净水技术中。
根据本发明的实施例，气凝胶基体中的吸湿聚合物的具体材料不受特别限制，只要具有较好的吸湿性能，且与石墨烯之间具有一定的兼容性即可。例如，可利用多亲水基聚合物形成气凝胶基体中的吸湿聚合物。在本发明中，术语“多亲水基聚合物”特指聚合物单体中包括亲水基的材料，例如单体中可以包括羧基、羟基、以及磺酸基的至少之一。例如具体地，吸湿聚合物可以包括聚丙烯酸及其盐、海藻酸及其盐、聚苯乙烯磺酸及其盐。例如，聚丙烯酸钠(Sodium polyacrylate，以下简称PAAS)自身吸水性能较好，且可以与石墨烯气凝胶的骨架结构可以较好的融合，从而可进一步提高该光热转换材料的水汽吸附量，同时保证气凝胶基体可维持完整的块体结构。
在本发明提出的光热转换材料中，气凝胶基体中吸湿聚合物的质量以及石墨烯的质量不受特别限制，只要不影响气凝胶基体的成型，并可在吸收水蒸汽之后保持块体的完整性即可。例如，根据本发明一些具体的实施例，气凝胶基体中聚合物的质量和石墨烯的质量之比可以为0.1-1.5。更具体地，该气凝胶基体可以是由吸湿聚合物与氧化石墨烯溶液混合，后经过成型处理以及还原处理而形成的。在吸湿聚合物与氧化石墨烯的混合溶液中，吸湿聚合物的质量与氧化石墨烯的质量之比可以为0.01～0.8，例如，可以为10％、15％、20％、25％、40％、60％等。氧化石墨烯经过还原处理，还原为石墨烯，且该过程不影响氧化石墨烯以及吸湿聚合物气凝胶块体的成型，含氧化石墨烯的气凝胶在经过还原处理之后，气凝胶基体仍旧可以保持良好的块体结构，且具有一定的机械性能，在经过多次水汽的吸收和脱附之后，块体并无显著的碎裂、掉渣等情况出现。例如具体地，光热转换材料中聚丙烯酸盐的质量以及石墨烯的质量之比可以为0.25～0.65。
根据本发明的实施例，由于气凝胶基体兼具了石墨烯良好的光热转换性能，以及吸湿聚合物(如PAAS，聚丙烯酸钠)的吸湿性能，因此该光热转换材料可在全湿度范围内吸收空气中的水分。并且，气凝胶基体具有多孔结构，多孔结构的孔径为25～60微米。孔径范围在上述范围内的气凝胶一方面可以保证具有较大的比较面积，从而提高该光热转换材料的吸水量，另一方面也可以保证该气凝胶基体的机械性能。根据本发明实施例的光热转换材料的饱和吸水量可达到5.05g/g。
为了进一步提高该光热转换材料的光热转换性能，该光热转换材料中还可以进一步包括金属催化剂颗粒，例如，可包括金属或是金属氧化物催化剂颗粒。该气凝胶基体的多孔结构可以为催化剂颗粒提供良好的负载基体，且石墨烯气凝胶也可以通过诸如在水热成型过程中加入金属盐等方式，简便地将金属催化剂颗粒整合在气凝胶基体上。
根据本发明的实施例，上述光热转换材料在全光谱范围内的吸光度可高于95％。该光热转换材料具有良好的光热转换效率，可将太阳光中的绝大多数光能转换为热能。并且， 该光热转换材料在1kW/m 2的光强照射下，光热转换材料的表面温度可大于85摄氏度。也即是说，由于该光热转换材料具有良好的光热转换效率，因此自发吸附在该光热转换材料内部的水蒸汽(凝结为液态水)可在材料表面自发地蒸发脱离，发生自主脱附，从而无需额外供能，即可实现净水(水蒸汽)的回收。
上述光热转换材料的组分简单，制备方法也不受特别限制，并可以简单的扩大生产规模。较为理想的石墨烯以及吸湿聚合物配比不仅可保证该光热转换材料可具有较好的光热转换效率以及产水量，并且该组分在扩大生产(即扩大单次制备的气凝胶基体的体积)时，也可以保证大块的气凝胶基体也能够较好的成型，从而免去了需要额外提供基体以及将光热转换材料进行负载的操作。
在本发明的另一方面，本发明提出了一种制备前面描述的光热转换材料的方法。具体地，参考图1，该方法包括：
S100：形成气凝胶前驱体
根据本发明的实施例，在该步骤中，首先将氧化石墨烯以及吸湿聚合物混合并冻干形成气凝胶基体前驱体。
具体地，可以将氧化石墨烯溶液以及含有吸湿聚合物的溶液进行混合。以采用聚丙烯酸钠为吸湿聚合物为例，混合溶液可以为氧化石墨烯溶液以及聚丙烯酸钠的水溶液。更具体地，混合可以是利用涡旋振荡器剧烈震荡而实现的，以令氧化石墨烯以及聚丙烯酸钠在混合溶液中混合均匀，并可以辅以超声处理，例如，可在进行涡旋振荡之后进行10min左右的超声处理。
如前所述，混合溶液中氧化石墨烯以及聚丙烯酸钠的具体含量不受特别限制，只要在后续经过还原之后，可令气凝胶基体中的聚合物的质量和石墨烯的质量之比在0.05～0.8的范围内即可。例如，具体地，可以选用10～20mg/ml的氧化石墨烯溶液，混以聚丙烯酸钠水溶液，并加入适量去离子水，令混合溶液中氧化石墨烯的最终浓度为3－7mg/ml，混合溶液中PAAS的质量与为氧化石墨烯质量的比为0.01～0.35即可，例如，可以为10％、15％、20％、25％、40％、60％等。由此，便于利用冻干形成气凝胶前驱体。
根据本发明的具体实施例，冻干处理可以是在－30～－60摄氏度下进行的，冻干时间可以为30～50小时。具体地，可以将上述溶液倒入任意模具中，在液氮表面冷冻，即利用液氮进行表面冷冻，随后用冷冻干燥机在-50℃下干燥48h。
为了进一步提高冻干之后获得的气凝胶前驱体的成型性能，可以在混合溶液进行冻干之前，预先在混合溶液中加入乙醇溶液。例如，乙醇溶液和混合溶液的体积比可以为(1：25)～(1：35)，例如，可以为1：30。由此，可进一步提高混合溶液冻干后的成型性能。发明人发现，加入乙醇可以降低混合溶液的表面张力，并防止冷冻过程中不均匀形成冰晶 造成样品碎裂。
为了进一步提高该光热转换材料的光热转换性能，该光热转换材料中还可以进一步包括金属催化剂颗粒，例如，可包括金属或是金属氧化物催化剂颗粒。该气凝胶基体的多孔结构可以为催化剂颗粒提供良好的负载基体。具体地，可以在冻干之前的混合溶液中，加入包括但不限于金属盐溶液或是金属颗粒并混合，即可在冻干成型的过程中将金属颗粒复合在气凝胶基体上。或者，也可以通过包括但不限于溶剂热的过程，将金属盐溶液转换为金属氧化物等具有光热转换或是提升导热性能的颗粒，从而充当金属催化剂，负载在气凝胶基体上。
S200：对气凝胶前驱体进行还原处理
在该步骤中，对气凝胶前驱体进行还原处理，以形成气凝胶基体，并获得所述光热转换材料。该方法操作简单，便于扩大生产规模，且获得的光热转换材料至少具有以下优点的至少之一：可用湿度范围较宽、水汽可自主脱附、水汽吸附量大等。
根据本发明的实施例，还原处理可以包括：将气凝胶前驱体以及水合肼溶液置于密闭容器中以将气凝胶前驱体中的氧化石墨烯还原为石墨烯。具体地，还原处理可以是加热70－100摄氏度，加热时间为4－16小时。由此，可简便地将气凝胶前驱体中的氧化石墨烯还原为石墨烯。
下面将结合实施例对本发明的方案进行解释。本领域技术人员将会理解，下面的实施例仅用于说明本发明，而不应视为限定本发明的范围。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。
实施例1：
1.通过Hummers法制备氧化石墨烯溶液，通过离心将其浓度调至15mg mL -1。
2.取上述溶液10mL，加入聚丙烯酸钠溶液(2.7mg.mL -1)13.9mL，去离子水6.1mL，得到PAAS/GO(氧化石墨烯)质量比为1/4的溶液。加入乙醇1mL，超声处理15min。
3.将上述混合溶液倒入模具中，在液氮表面进行冷冻，随后使用冷冻干燥机在-50摄氏度冷冻干燥48h，得到GO/PAAS气凝胶。
4.将上述气凝胶放置于密闭容器内，加入1mL水合肼(80％)溶液，于80摄氏度烘箱内还原12h，得到气凝胶基体。气凝胶基体中PAAS的质量以及石墨烯的质量之比为0.5。
实施例2：
其余步骤同实施例1，所不同的是，在形成冻干的混合溶液时，配置得到PAAS/GO质量比为1:10的溶液。气凝胶基体中PAAS的质量以及石墨烯的质量之比为0.2。
实施例3：
其余步骤同实施例1，所不同的是，在形成冻干的混合溶液时，配置得到PAAS/GO质量比为1:7的溶液。气凝胶基体中PAAS的质量以及石墨烯的质量之比为0.28。
实施例4：
其余步骤同实施例1，所不同的是，在形成冻干的混合溶液时，配置得到PAAS/GO质量比为1:5的溶液。气凝胶基体中PAAS的质量以及石墨烯的质量之比为0.4。
实施例5：
其余步骤同实施例1，所不同的是，在形成冻干的混合溶液时，配置得到PAAS/GO质量比为1:3的溶液。气凝胶基体中PAAS的质量以及石墨烯的质量之比为0.67。
实施例6：
其余步骤同实施例1，所不同的是，采用海藻酸钠为吸湿聚合物，在形成冻干的混合溶液时，配置得到海藻酸：GO质量比为1：4的溶液。气凝胶基体中海藻酸的质量以及石墨烯的质量之比为0.5。
实施例7：
其余步骤同实施例1，所不同的是，采用海藻酸钠为吸湿聚合物，在形成冻干的混合溶液时，配置得到海藻酸钠：GO质量比为1：7的溶液。气凝胶基体中海藻酸的质量以及石墨烯的质量之比为0.28。
实施例8：
其余步骤同实施例1，所不同的是，采用聚苯乙烯磺酸为吸湿聚合物，在形成冻干的混合溶液时，配置得到聚苯乙烯磺酸：GO质量比为1：5的溶液。气凝胶基体中聚苯乙烯磺酸的质量以及石墨烯的质量之比为0.4。
实施例9：
其余步骤同实施例1，所不同的是，采用聚苯乙烯磺酸钠为吸湿聚合物，在形成冻干的混合溶液时，配置得到聚苯乙烯磺酸钠：GO质量比为1：5的溶液。气凝胶基体中聚苯乙烯磺酸钠的质量以及石墨烯的质量之比为0.4。
对比例1：
1.通过Hummers法制备氧化石墨烯溶液，通过离心将其浓度调至15mg mL -1.
2.取上述溶液30mL。加入乙醇1mL，超声处理15min式溶液混合均匀。
3.将上述混合溶液倒入模具中，在液氮表面进行冷冻，随后使用冷冻干燥机在-50摄氏度冷冻干燥48h，得到GO气凝胶。
4.将上述气凝胶放置于密闭容器内，加入1mL水合肼(80％)溶液，于80摄氏度烘箱内还原12h，得到所述PGF气凝胶(Sodium polyacrylate/graphene framework)。
对比例2：
其余步骤同实施例1，所不同的是，在形成冻干的混合溶液时，配置得到PAAS/GO质量比为0.35/1的溶液。气凝胶基体中PAAS的质量以及石墨烯的质量之比为0.7。
对比例3：
其余步骤同实施例1，所不同的是，在形成冻干的混合溶液时，配置得到PAAS/GO质量比为1:20的溶液。气凝胶基体中PAAS的质量以及石墨烯的质量之比为0.1。
对比例4：
其余步骤同实施例1，所不同的是，在冻干之前不加入乙醇溶液。
性能表征：
将气凝胶材料进行扫描电镜(SEM)表征，实施例1-9均具有类似的形貌。以实施例1为例，参考图2以及图3，从样品上表面的SEM,可以看出该光热转换材料具有孔径分布在30-50微米的多孔结构。
对实施例1-9进行太阳光全光谱范围(250～2500nm)的吸收率以及全湿度范围内对水汽吸收效果的测试，实施例1-9均具有较好的吸光能力以及水吸收率。以实施例1的测试结果为例，参考图4，光热转换材料的光吸收率为95％，对太阳光具有很好的吸收，而纯PAAS制备的体积相同的块体材料，基本不具有吸光能力。
参考图5，实施例1获得的光热转换材料，在全湿度范围内对水汽吸收效果良好，速率较快，且参考图6，该光热转换材料可以具有高达5.05g/g的吸水量，即：1g光热转换材料可吸收质量在其5倍以上的水量。
对实施例1-5以及对比例1-3在饱和湿度下吸收水汽24h，以测试上述实施例和对比例的饱和吸水量。测试时间为24h(图7)。饱和吸水量在PAAS/GO质量比为1/4时效果最好，当PAAS/GO质量比为0.35:1时，饱和吸水量有明显下降。这可能是由于PAAS负载过多造成的结构坍塌而导致的。
参考图8，不加入乙醇，难以得到较为完整的大块状光热转换材料，但并不影响已成型部分的材料的光热转换性能。
以上详细描述了本发明的实施方式，但是，本发明并不限于上述实施方式中的具体细节，在本发明的技术构思范围内，可以对本发明的技术方案进行多种简单变型，这些简单变型均属于本发明的保护范围。另外需要说明的是，在上述具体实施方式中所描述的各个具体技术特征，在不矛盾的情况下，可以通过任何合适的方式进行组合。
在本发明的描述中，需要理解的是，术语“上”、“下”、“外”、“内”、“顶”、“底”等指示 的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本发明和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本发明的限制。
在本说明书的描述中，参考术语“一个实施例”、“一些实施例”、“示例”、“具体示例”、或“一些示例”等的描述意指结合该实施例或示例描述的具体特征、结构、材料或者特点包含于本发明的至少一个实施例或示例中。在本说明书中，对上述术语的示意性表述不必须针对的是相同的实施例或示例。而且，描述的具体特征、结构、材料或者特点可以在任一个或多个实施例或示例中以合适的方式结合。此外，在不相互矛盾的情况下，本领域的技术人员可以将本说明书中描述的不同实施例或示例以及不同实施例或示例的特征进行结合和组合。
尽管上面已经示出和描述了本发明的实施例，可以理解的是，上述实施例是示例性的，不能理解为对本发明的限制，本领域的普通技术人员在本发明的范围内可以对上述实施例进行变化、修改、替换和变型。

Claims (20)

  1. 一种光热转换材料，包括：
    气凝胶基体，所述气凝胶基体包括石墨烯以及吸湿聚合物。
  2. 根据权利要求1所述的光热转换材料，所述吸湿聚合物包括多亲水基聚合物。
  3. 根据权利要求2所述的光热转换材料，形成所述多亲水基聚合物的单体包括羧基化合物、羟基化合物、以及磺酸基化合物的至少之一。
  4. 根据权利要求1-3任一项所述的光热转换材料，所述吸湿聚合物包括聚丙烯酸化合物以及聚丙烯酸盐、海藻酸化合物以及海藻酸盐、聚苯乙烯磺酸化合物以及聚苯乙烯磺酸盐。
  5. 根据权利要求1-4任一项所述的光热转换材料，所述气凝胶基体中，所述吸湿聚合物的质量以及所述石墨烯的质量之比为0.1～1.5。
  6. 根据权利要求5所述的光热转换材料，所述气凝胶基体中，所述吸湿聚合物为聚丙烯酸盐，所述聚丙烯酸盐的质量以及所述石墨烯的质量之比为0.25～0.65。
  7. 根据权利要求1-6任一项所述的光热转换材料，所述气凝胶基体可在全湿度范围内吸收空气中的水分。
  8. 根据权利要求1-7任一项所述的光热转换材料，所述气凝胶基体具有多孔结构。
  9. 根据权利要求8所述的光热转换材料，所述多孔结构的孔径为25～60微米。
  10. 根据权利要求1-9任一项所述的光热转换材料，所述光热转换材料的饱和吸水量可达到5.05g/g。
  11. 根据权利要求1-10任一项所述的光热转换材料，所述光热转换材料在全光谱范围内的吸光度可高于95％。
  12. 根据权利要求1-11任一项所述的光热转换材料，在1kW/m 2的光强照射下，所述光热转换材料的表面温度可大于85摄氏度。
  13. 一种制备权利要求1-12任一项所述的光热转换材料的方法，所述方法包括：
    将氧化石墨烯以及吸湿聚合物混合并形成气凝胶基体前驱体；
    对所述气凝胶基体进行还原处理，以形成气凝胶基体，并获得所述光热转换材料。
  14. 根据权利要求13所述的方法，将氧化石墨烯溶液以及含有所述吸湿聚合物的溶液进行混合，混合溶液中所述氧化石墨烯的浓度为3－7mg/ml，所述混合溶液中所述吸湿聚合物的质量和所述氧化石墨烯质量的比为0.05～0.8。
  15. 根据权利要求13或14所述的方法，所述气凝胶基体前驱体是通过对所述氧化石墨烯以及吸湿聚合物的混合物进行冻干处理而获得的。
  16. 根据权利要求15所述的方法，在进行所述冻干之前，对所述混合溶液进行震荡混 合以及超声混合处理。
  17. 根据权利要求15或16所述的方法，所述冻干处理是在－30～－60摄氏度下冻干30～50小时。
  18. 根据权利要求15-17任一项所述的方法，将所述氧化石墨烯以及所述吸湿聚合物进行混合之后，进行冻干之前，预先在混合溶液中加入乙醇溶液。
  19. 根据权利要求18所述的方法，所述乙醇溶液和所述混合溶液的体积比为(1：25)～(1：35)。
  20. 根据权利要求13-19任一项所述的方法，所述还原处理包括：将所述气凝胶前驱体以及水合肼溶液置于密闭容器中，加热70－100摄氏度，加热时间为4－16小时。
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