Cellulose-based radiation refrigeration hybrid material and preparation method thereof

Abstract

The invention discloses a cellulose-based radiation cooling hybrid material and a preparation method thereof, and belongs to the technical field of radiation cooling materials. The method disclosed by the invention comprises the following steps: S1, dissolving fiber slurry in a zinc chloride aqueous solution, and then carrying out stirring reaction to obtain a cellulose solution; s2, deionized water is added into the cellulose solution, stirring reaction is performed, and micro-nano fiber suspension liquid is obtained; s3, carrying out post-treatment on the micro-nano fiber suspension to obtain a treated micro-nano fiber suspension; s4, mixing the micro-nano fiber suspension liquid with deionized water to obtain a cellulose dispersion liquid; s5, after the pH value of the cellulose dispersion liquid is adjusted, stirring reaction and washing treatment are conducted in sequence, and the cellulose-based radiation refrigeration hybrid material is obtained. No organic solvent is added in the reaction process, the zinc chloride solvent can be recycled, the environment protection concept is met, industrial production of the ZnO / regenerated cellulose hybrid material can be achieved, and remarkable benefits are achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of radiative cooling materials, and particularly relates to a cellulose-based radiative cooling hybrid material and a preparation method thereof. BACKGROUND

[0002] With the increasingly serious global energy crisis and climate change, it is urgent to develop green refrigeration technology with zero energy consumption and zero carbon emission. The radiative cooling (PDRC) technology is considered as a potential sustainable development technology because it can continuously cool down by radiating heat to the cold outer space (about 3 K) through the "atmospheric transparent window" (8-13 μm) without consuming any external energy. However, for daytime radiative cooling, it is necessary to have high reflectivity in the solar spectrum band (0.3-2.5 μm) to minimize the absorption of solar heat, and at the same time, have high infrared emissivity in the atmospheric window band to maximize the radiation of heat to the outer space.

[0003] In the field of passive daytime radiative cooling (PDRC) materials, high refractive index inorganic scatterers such as zinc oxide (ZnO) have attracted widespread attention because they can significantly improve the solar reflectivity. ZnO has high refractive index (n≈2) and low absorption characteristics in a wide spectral range, and is often used to build PDRC materials by compounding with polymers. However, such composite materials have the following obvious deficiencies: ZnO has poor compatibility with the organic matrix, is difficult to disperse uniformly, easily introduces interface defects, and leads to a decrease in optical performance; at the same time, the high filler load (>50 wt%) required to achieve high reflectivity performance also causes processing difficulties and degradation of mechanical properties. Although surface modification techniques can partially improve the dispersibility and interface bonding, such methods are usually complex and costly, and are difficult to achieve large-scale production.

[0004] As a renewable and biodegradable natural polymer, cellulose has high infrared emissivity and abundant functional groups, and is considered as an ideal PDRC matrix material. Its surface hydroxyl groups and three-dimensional network structure can provide nucleation sites and dispersion templates for ZnO. However, the low accessibility of natural cellulose hydroxyl groups limits the effective nucleation and uniform distribution of ZnO. By nanocrystallization or functionalization (such as carboxylation) modification of cellulose, the surface charge and number of active sites can be increased, and the dispersion and interface bonding of ZnO can be improved. However, the adsorption and multi-level assembly of ZnO still need further research to achieve structure controllability and performance optimization. Therefore, it is of great practical significance to develop a cellulose-based PDRC material with simple process, environmental friendliness, high solar reflectivity and high infrared emissivity, and which can be suitable for large-scale production. 2+ adsorption and multi-level assembly of ZnO, but this direction still needs further research to achieve structure controllability and performance optimization. Therefore, it is of great practical significance to develop a cellulose-based PDRC material with simple process, environmental friendliness, high solar reflectivity and high infrared emissivity, and which can be suitable for large-scale production. SUMMARY

[0005] The cellulose-based radiation refrigeration hybrid material and the preparation method thereof solve the technical problem that the existing preparation method does not conform to the environmental protection concept.

[0006] In order to achieve the above-mentioned purpose, the following technical solutions are adopted: The application discloses a preparation method of a cellulose-based radiation refrigeration hybrid material, and comprises the following steps: S1: dissolving fiber slurry in a zinc chloride aqueous solution, and then performing stirring reaction to obtain a cellulose solution; S2: adding deionized water into the cellulose solution, and performing stirring reaction to obtain a micro-nano fiber suspension; S3: performing post-treatment on the micro-nano fiber suspension to obtain treated micro-nano fiber suspension; S4: mixing the micro-nano fiber suspension and deionized water to obtain a cellulose dispersion; S5: after adjusting the pH value of the cellulose dispersion, performing stirring reaction and washing treatment in sequence to obtain the cellulose-based radiation refrigeration hybrid material.

[0007] Further, in S1, the preparation method of the zinc chloride aqueous solution is as follows: completely dissolving zinc chloride and water under stirring to obtain a zinc chloride aqueous solution; the molar ratio of the zinc chloride and water is 1:2-1:5; the stirring is magnetic stirring; the rotating speed of the magnetic stirring is 200-400 rpm.

[0008] Further, in S1, the stirring reaction is performed at a temperature of 50-120 DEG C, a rotating speed of 100-500 rpm, and a reaction time of 1-2.5 h; the mass ratio of the fiber slurry and the zinc chloride aqueous solution is 1:20-1:50.

[0009] Further, in S2, the addition amount of the deionized water is 150%-500% of the mass of the zinc chloride aqueous solution; the rotating speed of the stirring reaction is 100-300 rpm, and the reaction time is 1-3 h.

[0010] Further, in S3, the post-treatment of the micro-nano fiber suspension specifically comprises the following steps: centrifuging the micro-nano fiber suspension and repeatedly cleaning the micro-nano fiber suspension in deionized water until neutral.

[0011] Further, in S4, the solid content of the cellulose dispersion is 3 wt%-12 wt%.

[0012] Further, in S5, the pH value of the cellulose dispersion liquid is adjusted to 8-13; the temperature of the stirring reaction is 60-150 DEG C, the rotating speed is 100-300 rpm, and the reaction time is 1-4 h.

[0013] Further, NaOH is used to adjust the pH value; the concentration of the NaOH is 1-10 mol / L.

[0014] The application further discloses the cellulose-based radiation refrigeration hybrid material prepared by the preparation method.

[0015] Further, the reflectivity in the sunlight band is 98.7%, and the emissivity in the 8-13-micron atmospheric transmission window is 96.7%.

[0016] Compared with the prior art, the application has the following beneficial effects: The application discloses a preparation method of a cellulose-based radiation refrigeration hybrid material, adopts a zinc chloride aqueous solution as a solvent to dissolve fiber pulp to obtain regenerated micro-nano fibers, then the reactants are precipitated by adding water to form uniformly dispersed micro-nano fibers in an aqueous phase, the ZnO / regenerated cellulose hybrid material is prepared by green solvent dissolution and in-situ growth, the reaction process does not add an organic solvent, the zinc chloride solvent can be recycled, conforms to the environmental protection concept, the ZnO / regenerated cellulose hybrid material can realize industrialized production, and has significant benefits.

[0017] Further, the molar ratio of the zinc chloride and water is limited to 1:2-1:5 in the method, because it is found through creative experiments that when the molar ratio of the zinc chloride and water is less than 1:2 or greater than 1:5, the cellulose cannot be dissolved, and it is difficult to obtain regenerated micro-nano fibers; and the mass ratio of the fiber pulp and the zinc chloride aqueous solution is limited to 1:20-1:50, because it is found through creative experiments that when the mass ratio of the fiber pulp and the zinc chloride aqueous solution is less than 1:20, the viscosity of the system increases, the cellulose is partially swelled, and the reaction is incomplete.

[0018] Further, the method limits the addition amount of the deionized water to 150%-500% of the mass of the zinc chloride aqueous solution, because it is found through creative experiments that when the addition amount of the water is less than 80% of the content of the zinc chloride aqueous solution, the reactant system cannot be completely precipitated in water, which leads to uneven size and uneven dispersion of the cellulose; and the addition amount of the water has no upper limit, and different solid content aqueous dispersions can be prepared according to requirements.

[0019] Further, the method limits the solid content of the cellulose dispersion liquid to 3 wt%-12 wt%, because it is found through creative experiments that when the solid content of the cellulose dispersion liquid is greater than 7 wt%, the system reaction is uneven.

[0020] The application also discloses the cellulose-based radiation refrigeration hybrid material prepared by the preparation method. The multi-stage structure of the high-refractive-index ZnO in the material can form a strong light scattering effect, so that the refrigeration material has high sunlight reflectivity (98.7%). The cellulose contains a large number of mid-infrared absorption chemical groups (for example, C-O and C-O-C) in the 'atmospheric window' wave band, so that the cellulose has excellent long-wave infrared emissivity (96.7%). The ZnO / regenerated cellulose hybrid material is simple to prepare, has no toxic reagent, and the solvent can be recycled and reused, and has obvious low cost and environmental friendly characteristics. The ZnO / regenerated cellulose hybrid material can be uniformly dispersed in an aqueous phase, and has no obvious agglomeration and stratification phenomenon after being placed for one month, and is suitable for large-scale processing and the like. The ZnO / regenerated cellulose hybrid material is suitable for a new generation of green, low-cost and large-scale application radiation refrigeration material. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A sample physical picture of the ZnO / cellulose hybrid material prepared in Example 2 of the application; Figure 2 A scanning electron microscope picture of the ZnO / cellulose hybrid material sample prepared in Example 4 of the application; Figure 3 An ultraviolet-visible-near-infrared reflectivity spectrum picture of the ZnO / cellulose hybrid material prepared in Example 1 of the application in the range of 0.3-2.5 μm; Figure 4 An infrared emissivity spectrum picture of the ZnO / cellulose hybrid material prepared in Example 3 of the application in the range of 8-13 μm; Figure 5 Data of the ZnO / cellulose hybrid material sample prepared in Example 5 of the application in the process of outdoor testing; Wherein: (a) - environmental data; (b) - actual radiation refrigeration effect. DETAILED DESCRIPTION

[0022] In order for those skilled in the art to understand the characteristics and effects of the present application, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used in the text are the usual meanings understood by those skilled in the art for the present application, and in case of conflict, the definition in the specification shall prevail.

[0023] Theories or mechanisms described and disclosed herein, whether correct or not, should not be used to limit the scope of the present application, i.e., the present application can be practiced without being limited by any particular theory or mechanism.

[0024] Herein, all features defined by a numerical range or a percentage range, such as numerical values, amounts, contents and concentrations, are for the sake of brevity and convenience only. Accordingly, the description of a numerical range or a percentage range should be considered to have encompassed and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0025] Herein, unless otherwise specifically indicated, the terms "comprise", "comprising", "contain", "containing", "have", "having", or any other similar phrase are intended to encompass "consist of" and "consist essentially of" for example, "A comprises a" encompasses "A comprises a and other" and "A comprises only a".

[0026] Herein, in order to make the description brief, all possible combinations of the technical features in each embodiment or example are not described. Therefore, the technical features in each embodiment or example can be combined with each other arbitrarily, and all possible combinations should be considered as the scope of the present specification.

[0027] The cellulose-based ZnO / regenerated cellulose hybrid material has the following advantages: simple preparation, no toxic reagents, and recyclable solvent, uniform dispersion in aqueous phase, and no obvious agglomeration and delamination phenomenon after one month, high reflection and emission performance, suitable for spraying, dipping, blending and other processing methods, and suitable for large-scale processing, etc. The present application provides a preparation method of a cellulose-based radiation refrigeration hybrid material, comprising the following steps: Step 1: zinc chloride and water are mixed in a molar ratio of 1:2~1:5, and magnetically stirred at a stirring speed of 100~500 rpm until completely dissolved to form a zinc chloride aqueous solution; Step 2: the fiber slurry is dissolved in the zinc chloride aqueous solution, and reacted at 50~120℃ under the condition of a stirring speed of 100~500 rpm for 1~2.5h to obtain a clear cellulose solution; the mass ratio of the absolutely dry fiber slurry to the zinc chloride aqueous solution is 1:20~1:50; Step 3: deionized water is added to the cellulose solution obtained in step 2, and completely precipitated under the condition of a stirring speed of 100~300 rpm for 1~3h to obtain a micro-nano fiber suspension; then the micro-nano fiber suspension is centrifuged and repeatedly washed in deionized water until neutral to ensure that the free zinc ions are completely removed; the amount of deionized water added is 150%~500% of the mass of the zinc chloride aqueous solution; Step 4: The micro-nano fiber suspension is configured into a cellulose dispersion liquid with a solid content of 3 wt%-12 wt%, and then the pH of the dispersion liquid is adjusted to 8-13 by NaOH, and the zinc oxide / cellulose hybrid material is obtained by reacting at 60-150 DEG C under stirring at 100-300 rpm for 1-4 h, and the zinc oxide / cellulose hybrid material is centrifuged and repeatedly washed in deionized water until neutral, to obtain a cellulose-based radiative refrigeration hybrid material.

[0028] Preferably, in step 1, the molar ratio of zinc chloride to water is 1:3-1:4, and the stirring speed is 300 rpm.

[0029] Preferably, in step 2, the reaction temperature is 60-100 DEG C, and the stirring speed is 300 rpm for 2 h.

[0030] Preferably, in step 3, the stirring speed is 200 rpm, the reaction time is 1.5-2.5 h, and the amount of deionized water added is 200%-400% of the mass of the zinc chloride aqueous solution.

[0031] Preferably, in step 3, the reaction time is 2 h, and the amount of deionized water added is 250%-300% of the mass of the zinc chloride aqueous solution.

[0032] Preferably, in step 4, the reaction temperature is 100 DEG C, the stirring speed is 200 rpm, and the reaction time is 2-3 h.

[0033] Preferably, in step 4, the solid content of the cellulose dispersion liquid is 4 wt%-7 wt%, the reaction pH is 9, the reaction time is 2 h, and the concentration of NaOH is 3 mol / L.

[0034] The cellulose-based ZnO / regenerated cellulose hybrid material has the following advantages: simple preparation, no toxic reagents, and recyclable solvent, uniform dispersion in aqueous phase, no obvious agglomeration and delamination after one month, high reflection and emission performance, suitable for spraying, dipping, blending and other processing methods, and suitable for large-scale processing.

[0035] The application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the application and not to limit the scope of the application. Furthermore, it should be understood that those skilled in the art can make various modifications or changes to the application after reading the content taught by the application, and these equivalent forms also fall within the scope of the appended claims.

[0036] The following examples use apparatus and equipment that are conventional in the art. The experimental methods in the following examples, unless otherwise specified, are generally conducted under conventional conditions, or under conditions recommended by the manufacturer. The following examples use various raw materials, unless otherwise specified, which are conventional commercially available products, and the specifications thereof are conventional in the art. In the specification of the present application and in the following examples, unless otherwise specified, "%" means weight percent, "parts" means weight parts, and the ratio means weight ratio.

[0037] Example 1 A method for preparing a cellulose-based radiative cooling hybrid material, comprising the following steps: Step 1: zinc chloride and water are stirred at a stirring speed of 300 rpm in a magnetic stirrer until completely dissolved to form a 100 mL zinc chloride aqueous solution at a molar ratio of 1:3; Step 2: 5 g of bamboo pulp is dissolved in the zinc chloride aqueous solution, and a clear cellulose solution is obtained by reacting at 60 °C for 2.5 h under stirring at a stirring speed of 200 rpm; Step 3: 200 mL of deionized water is added to the cellulose solution obtained in Step 2, and the reaction is carried out for 1 h under stirring at a stirring speed of 300 rpm until the cellulose solution is completely precipitated to obtain a micro-nano fiber suspension; then the micro-nano fiber suspension is centrifuged and repeatedly washed in deionized water until neutral to ensure that free zinc ions are completely removed; Step 4: the micro-nano fiber suspension is configured into a cellulose dispersion liquid with a solid content of 4 wt%, and then the pH of the dispersion liquid is adjusted to 8 by using NaOH, and a zinc oxide / cellulose hybrid material is obtained by reacting at 60 °C for 1 h under stirring at a stirring speed of 200 rpm; the zinc oxide / cellulose hybrid material is centrifuged and repeatedly washed in deionized water until neutral to obtain a ZnO / cellulose hybrid material (cellulose-based radiative cooling hybrid material); the concentration of the NaOH is 1 mol / L.

[0038] Example 2 A method for preparing a cellulose-based radiative cooling hybrid material, comprising the following steps: Step 1: zinc chloride and water are stirred at a stirring speed of 200 rpm in a magnetic stirrer until completely dissolved to form a 100 mL zinc chloride aqueous solution at a molar ratio of 1:3; Step 2: 5 g of bamboo pulp is dissolved in the zinc chloride aqueous solution, and a clear cellulose solution is obtained by reacting at 80 °C for 1 h under stirring at a stirring speed of 500 rpm; Step 3: 200 mL deionized water was added to the cellulose solution obtained in step 2, and completely precipitated under the stirring speed of 300 rpm, and the reaction time was 3 h, to obtain a micro-nano fiber suspension; then the micro-nano fiber suspension was centrifuged and repeatedly washed in deionized water until neutral, to ensure that the free zinc ions were completely removed; Step 4: The micro-nano fiber suspension was configured into a cellulose dispersion liquid with a solid content of 5 wt%, and then the pH of the dispersion liquid was adjusted to 10 by using NaOH, and the reaction was carried out at 80 ℃ under the stirring speed of 300 rpm for 2 h, to obtain a zinc oxide / cellulose hybrid material, and the zinc oxide / cellulose hybrid material was centrifuged and repeatedly washed in deionized water until neutral, to obtain a ZnO / cellulose hybrid material (cellulose-based radiative cooling hybrid material); the concentration of the NaOH was 2 mol / L.

[0039] Example 3 A preparation method of a cellulose-based radiative cooling hybrid material, comprising the following steps: Step 1: Zinc chloride and water were mixed according to the molar ratio of 1:4, and magnetically stirred until completely dissolved under the stirring speed of 400 rpm, to form 100 mL of a zinc chloride aqueous solution; Step 2: 5 g of bamboo pulp was dissolved in the zinc chloride aqueous solution, and the reaction was carried out at 80 ℃ under the stirring speed of 300 rpm for 1.5 h, to obtain a clear cellulose solution; Step 3: 200 mL deionized water was added to the cellulose solution obtained in step 2, and completely precipitated under the stirring speed of 300 rpm, and the reaction time was 2 h, to obtain a micro-nano fiber suspension; then the micro-nano fiber suspension was centrifuged and repeatedly washed in deionized water until neutral, to ensure that the free zinc ions were completely removed; Step 4: The micro-nano fiber suspension was configured into a cellulose dispersion liquid with a solid content of 5 wt%, and then the pH of the dispersion liquid was adjusted to 11 by using NaOH, and the reaction was carried out at 90 ℃ under the stirring speed of 300 rpm for 3 h, to obtain a zinc oxide / cellulose hybrid material, and the zinc oxide / cellulose hybrid material was centrifuged and repeatedly washed in deionized water until neutral, to obtain a ZnO / cellulose hybrid material (cellulose-based radiative cooling hybrid material); the concentration of the NaOH was 3 mol / L.

[0040] Example 4 A preparation method of a cellulose-based radiative cooling hybrid material, comprising the following steps: Step 1: Zinc chloride and water were mixed according to the molar ratio of 1:4, and magnetically stirred until completely dissolved under the stirring speed of 500 rpm, to form 100 mL of a zinc chloride aqueous solution; Step 2: 5 g of bamboo pulp was dissolved in zinc chloride aqueous solution, and a clear cellulose solution was obtained by stirring at 80 °C and 500 rpm for 2 h; Step 3: 200 mL of deionized water was added to the cellulose solution obtained in step 2, and the micro-nano fiber suspension was obtained by complete precipitation at a stirring speed of 300 rpm for 2 h; then the micro-nano fiber suspension was centrifuged and repeatedly washed in deionized water until neutral to ensure that the free zinc ions were completely removed; Step 4: The micro-nano fiber suspension was configured into a cellulose dispersion liquid with a solid content of 6 wt%, and then the pH of the dispersion liquid was adjusted to 12 by NaOH, and a zinc oxide / cellulose hybrid material was obtained by reacting at 130 °C and 300 rpm for 1 h; the zinc oxide / cellulose hybrid material was centrifuged and repeatedly washed in deionized water until neutral to obtain a ZnO / cellulose hybrid material (cellulose-based radiative cooling hybrid material); the concentration of NaOH was 4 mol / L.

[0041] Example 5 A method for preparing a cellulose-based radiative cooling hybrid material, comprising the following steps: Step 1: Zinc chloride and water were mixed according to a molar ratio of 1:5, and the mixture was magnetically stirred at a stirring speed of 500 rpm until completely dissolved to form 100 mL of zinc chloride aqueous solution; Step 2: 5 g of bamboo pulp was dissolved in zinc chloride aqueous solution, and a clear cellulose solution was obtained by stirring at 90 °C and 500 rpm for 1.5 h; Step 3: 200 mL of deionized water was added to the cellulose solution obtained in step 2, and the micro-nano fiber suspension was obtained by complete precipitation at a stirring speed of 100 rpm for 1.5 h; then the micro-nano fiber suspension was centrifuged and repeatedly washed in deionized water until neutral to ensure that the free zinc ions were completely removed; Step 4: The micro-nano fiber suspension was configured into a cellulose dispersion liquid with a solid content of 7 wt%, and then the pH of the dispersion liquid was adjusted to 13 by NaOH, and a zinc oxide / cellulose hybrid material was obtained by reacting at 150 °C and 300 rpm for 4 h; the zinc oxide / cellulose hybrid material was centrifuged and repeatedly washed in deionized water until neutral to obtain a ZnO / cellulose hybrid material (cellulose-based radiative cooling hybrid material); the concentration of NaOH was 9 mol / L.

[0042] As shown in Figure 1 the sample bottle, the prepared ZnO / cellulose hybrid material has obvious whiteness, and is stable in dispersion without obvious sedimentation and stratification.

[0043] As shown in Figure 2 , the cellulose fiber has a clear nanometer network structure, on which the micro-flower structure of uniformly dispersed ZnO is stably loaded, and the nanometer structure fiber network can produce good scattering effect on incident light of nanometer scale, and the microscale can produce good scattering effect on incident light of microscale.

[0044] As shown in Figure 3 , the ZnO / cellulose hybrid material with micro-nano structure can produce good scattering effect on light in the solar band (0.3~2.5 μm), thereby significantly enhancing the reflectivity of the cellulose radiation cooling material to sunlight and reducing the heating effect of sunlight on the material surface.

[0045] As shown in Figure 4 , the cellulose molecules in the ZnO / cellulose hybrid material contain a large number of emitting groups (C-O and C-O-C), which endow the ZnO / cellulose hybrid material with excellent atmospheric window infrared emissivity, so that it can emit thermal radiation through the atmospheric transparent window and realize passive cooling performance.

[0046] As shown in Figure 5 , the outdoor test results show that the temperature of the ZnO / cellulose hybrid material under the solar irradiation of 769 W / m 2 is 40 ℃, which is 11 ℃ lower than the outdoor temperature, and the significant cooling is realized.

[0047] The above content is only to illustrate the technical idea of the present application, and cannot limit the protection scope of the present application, and any modification made according to the technical idea of the present application on the basis of the technical scheme falls within the protection scope of the claims of the present application.

Claims

1. A method of preparing a cellulose-based radiative cooling hybrid material, characterized in that, The method comprises the following steps: S1: dissolving the fiber slurry in zinc chloride aqueous solution, and then stirring to obtain a cellulose solution; S2: adding deionized water to the cellulose solution, and stirring to obtain a micro-nano fiber suspension; S3: post-treating the micro-nano fiber suspension to obtain a treated micro-nano fiber suspension; S4: mixing the micro-nano fiber suspension and deionized water to obtain a cellulose dispersion; S5: adjusting the pH value of the cellulose dispersion, and then stirring and washing to obtain a cellulose-based radiation refrigeration hybrid material.

2. A method of preparing a cellulose-based radiative cooling hybrid material according to claim 1, characterized in that, In S1, the preparation method of the zinc chloride aqueous solution is as follows: completely dissolving zinc chloride and water under stirring to obtain a zinc chloride aqueous solution; the molar ratio of the zinc chloride and water is 1:2-1:5; the stirring is magnetic stirring; the rotating speed of the magnetic stirring is 200-400 rpm.

3. A method of preparing a cellulose-based radiative cooling hybrid material according to claim 1, characterized in that, In S1, the stirring temperature is 50-120 ℃, the rotating speed is 100-500 rpm, and the reaction time is 1-2.5 h; the mass ratio of the fiber slurry to the zinc chloride aqueous solution is 1:20-1:

50.

4. The method of claim 1, wherein the cellulose-based radiative cooling hybrid material is prepared by the steps of: In S2, the amount of the deionized water added is 150%-500% of the mass of the zinc chloride aqueous solution; the rotating speed of the stirring is 100-300 rpm, and the reaction time is 1-3 h.

5. The method of claim 1, wherein the cellulose-based radiative cooling hybrid material is prepared by the steps of: In S3, the post-treatment of the micro-nano fiber suspension comprises the following steps: centrifuging the micro-nano fiber suspension and repeatedly washing in deionized water until neutral.

6. The method of claim 1, wherein the cellulose-based radiative cooling hybrid material is prepared by the steps of: In S4, the solid content of the cellulose dispersion is 3 wt%-12 wt%.

7. A method of preparing a cellulose-based radiative cooling hybrid material according to claim 1, characterized in that, In S5, the pH value of the cellulose dispersion is adjusted to 8-13; the stirring temperature is 60-150 ℃, the rotating speed is 100-300 rpm, and the reaction time is 1-4 h.

8. A method of preparing a cellulose-based radiative cooling hybrid material according to claim 7, characterized in that, NaOH is used to adjust the pH value; the concentration of the NaOH is 1-10 mol / L.

9. A cellulose-based radiative cooling hybrid material, characterized in that, The method is prepared by the preparation method in any one of claims 1-8.

10. The cellulose-based radiative cooling hybrid material of claim 9, wherein, The reflectivity in the solar wave band is 98.7%, and the emissivity in the 8-13 μm atmospheric transmission window is 96.7%.

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