Magnesium-doped aluminum phosphate passive radiation refrigeration material as well as preparation method and application thereof

Abstract

The invention discloses a magnesium-doped aluminum phosphate passive radiation refrigeration material as well as a preparation method and application thereof, and relates to the technical field of daytime passive radiation refrigeration. The method comprises the following steps: uniformly mixing aluminum lactate, MgCl2. 6H2O, trimesic acid, succinic acid and pyrophosphoric acid in a solvent to obtain a precursor solution; performing hydrothermal treatment on the precursor solution at the temperature of 100-150 DEG C to obtain a reaction solution, and washing and drying a product in the reaction solution to obtain magnesium-doped aluminum phosphate powder; and calcining the magnesium-doped aluminum phosphate powder at 700-1300 DEG C for 1-3 hours to obtain the magnesium-doped aluminum phosphate passive radiation refrigeration material. Magnesium-doped aluminum phosphate is synthesized at a certain heat treatment temperature by adopting a microwave-assisted hydrothermal method, and the magnesium-doped aluminum phosphate has excellent sunlight reflectivity and excellent mid-infrared emissivity and shows excellent performance in the field of radiation refrigeration.

Description

Technical Field

[0001] The present invention relates to the technical field of daytime passive radiation cooling, and in particular to a magnesium-doped aluminum phosphate passive radiation cooling material, a preparation method and an application thereof. Background Art

[0002] With global industrialization, global warming and energy shortages are becoming increasingly prominent. In summer, air conditioners and other cooling equipment are widely used in various fields. This not only exacerbates energy supply pressures but also leads to the production of greenhouse gases, further exacerbating global warming. Therefore, to address these issues, passive radiative cooling has attracted the attention of many researchers.

[0003] Passive radiative cooling is a new cooling method that achieves cooling without consuming additional energy. According to the second law of thermodynamics, the temperature difference between Earth and outer space causes heat transfer. Materials with high emissivity at the atmospheric window allow for unimpeded heat transfer to outer space. Therefore, passive radiative cooling materials must possess excellent reflectivity in both the solar and atmospheric window bands to achieve the most efficient cooling effect. Currently, research on passive radiative cooling materials focuses on designing multilayer structures. Professor Bao Hua's research group at Shanghai Jiao Tong University has designed a two-layer radiative cooling material consisting of a reflective layer composed of nano-titanium dioxide and an emissive layer composed of nano-silicon dioxide or silicon carbide. Its reflectivity reaches 90.07% and its emissivity reaches 90.11%. Professor Yu Nanfang's research group has developed a new porous coating, P(VdF-HFP)HP, with a solar reflectivity of 0.96 and an infrared emissivity of 0.97. Under direct sunlight, it can cool the ambient temperature by 6°C. Although these materials have excellent radiative cooling performance, the preparation process of these materials is complex and the cost is too high, making them unable to be promoted and applied on a large scale. Summary of the Invention

[0004] In response to the problems existing in the prior art, the present invention provides a magnesium-doped aluminum phosphate passive radiation refrigeration material, a preparation method and an application, in order to solve the problems of complex preparation process and high cost of the current passive radiation refrigeration material. A microwave-assisted hydrothermal method is used to synthesize magnesium-doped aluminum phosphate at a certain heat treatment temperature. The material has excellent solar reflectivity and excellent mid-infrared emissivity, and exhibits excellent performance in the field of radiation refrigeration.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for preparing a magnesium-doped aluminum phosphate passive radiation cooling material comprises the following steps:

[0007] S1, mixing aluminum lactate, MgCl2·6H2O, trimesic acid, succinic acid, and pyrophosphoric acid in a solvent, wherein the molar ratio of aluminum lactate to pyrophosphoric acid is (1-1.1):(0.5-0.55), and the molar ratio of aluminum lactate to MgCl2·6H2O is 1:(0.01-0.05), to obtain a precursor solution;

[0008] S2, hydrothermally treating the precursor solution at 100-150° C. to obtain a reaction solution, washing and drying the product in the reaction solution to obtain magnesium-doped aluminum phosphate powder;

[0009] S3, calcining the magnesium-doped aluminum phosphate powder at 700-1300° C. for 1-3 hours to obtain a magnesium-doped aluminum phosphate passive radiation refrigeration material.

[0010] A further improvement of the present invention is:

[0011] S1 obtains the precursor solution as follows:

[0012] Aluminum lactate, deionized water, and hydrochloric acid are stirred uniformly to obtain a first solution;

[0013] Dissolving MgCl2·6H2O in deionized water and stirring the obtained solution with the first solution to obtain a second solution;

[0014] The solution obtained by dissolving trimesic acid and succinic acid in dimethylformamide was stirred evenly with the second solution to obtain a third solution;

[0015] A solution obtained by dissolving pyrophosphoric acid in deionized water and the third solution are stirred evenly to obtain a precursor solution.

[0016] The mass percentage of hydrochloric acid in the first solution is 5% to 20%, and the ratio of hydrochloric acid to aluminum lactate is (10 to 20) ml: (0.003 to 0.02) mol.

[0017] The molar ratio of aluminum lactate, trimesic acid and succinic acid in S1 is

[0018] 1:(0.2~0.8):(0.2~0.8).

[0019] The precursor solution described in S2 is hydrothermally treated at 100-150° C. for 4-8 hours to obtain a reaction solution.

[0020] The hydrothermal treatment is carried out in a microwave synthesizer with a microwave power of 400-800W.

[0021] S2: filtering the product in the reaction solution, and then cross-cleaning with deionized water and ethanol to obtain a washed product, and then vacuum drying at 50-80° C. for 3-7 hours to obtain magnesium-doped aluminum phosphate powder.

[0022] S3 is first heated from room temperature to 300-400°C at a rate of 3-5°C / min, kept warm for 0.5-1h, then heated to 700-1300°C at a rate of 6-10°C / min, and calcined at 700-1300°C for 1-3h to obtain magnesium-doped aluminum phosphate passive radiation refrigeration material.

[0023] A magnesium-doped aluminum phosphate passive radiation cooling material obtained by any one of the above methods for preparing the magnesium-doped aluminum phosphate passive radiation cooling material.

[0024] Application of magnesium-doped aluminum phosphate passive radiative cooling material in passive radiative cooling.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] The present invention discloses a method for preparing a magnesium-doped aluminum phosphate passive radiation refrigeration material. Aluminum lactate, MgCl2·6H2O and pyrophosphoric acid can be used to synthesize magnesium-doped aluminum phosphate by a hydrothermal method under the action of trimesic acid and succinic acid. The aluminum phosphate material has relatively good refrigeration performance. Trimesic acid and succinic acid can prevent aluminum from forming hydroxide precipitation under acidic conditions and can complex with aluminum to enhance stability. 2+ and Al 3+ The difference in ion radius and charge between ions will cause the originally regular AlPO4 lattice to be distorted or deformed to a certain extent, thereby reducing the symmetry of the lattice and causing more vibration and rotation inside the crystal, thereby increasing the change in the molecular dipole moment and thus increasing the infrared emissivity. Furthermore, AlPO4 usually has a specific crystal symmetry and spatial arrangement, while Mg 2+ Replace part of Al 3+ After the position is changed, the original orderly arrangement of ions will be disrupted, resulting in a decrease in local symmetry and a decrease in the order of the lattice. This destructive effect makes the electrons in the crystal more active in vibration and rotation, thereby increasing the infrared emissivity. After heat treatment, the crystal structure will preferentially orient toward the peak with small interface energy, which will generate triclinic aluminum phosphate. This structure has the lowest symmetry of aluminum phosphate, which is beneficial to improving the emission performance of the material, and obtaining magnesium-doped aluminum phosphate passive radiation refrigeration material. The preparation process is simple, the reaction cycle is short, the raw materials are common, and the cost is low. It solves the problems of complex preparation process and high cost of current passive radiation refrigeration materials. It has strong controllability, can prepare target products in large quantities, and is easy to realize industrial production. Magnesium-doped aluminum phosphate powder has both high solar reflectivity and high and medium infrared emissivity, excellent cooling effect, and has excellent performance in the field of radiation refrigeration.

[0027] The present invention allows magnesium-doped aluminum phosphate powder to be pressed into tablets and used as a passive radiative cooling material. The tablets have high solar reflectivity, which allows the majority of sunlight to be reflected, thereby reducing absorption. Furthermore, they have high atmospheric window emissivity, allowing internal energy to be exchanged with outer space in the form of infrared rays, thereby reducing the material's heat and providing cooling. The material can also be used as a filler in latex paint and applied to log cabins, utilizing the excellent solar reflectivity and high atmospheric window emissivity of magnesium-doped aluminum phosphate to reduce the surface temperature of wood. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 These are the XRD patterns of Mg-doped AlPO4 and AlPO4 obtained in Examples 1, 2, and 4 of the present invention.

[0029] Figure 2 This is the XPS graph of Mg-doped AlPO4 obtained in Example 2 of the present invention.

[0030] Figure 3 This is the emissivity spectrum of Mg-doped AlPO4 in the mid-infrared band obtained in Example 2 of the present invention.

[0031] Figure 4 This is the reflectivity spectrum of Mg-doped AlPO4 in the solar band obtained in Example 2 of the present invention.

[0032] Figure 5 The cooling effect diagram of Mg-doped AlPO4 obtained in Example 2 of the present invention and Comparative Example 1 and the ambient temperature are shown.

[0033] Figure 6 The cooling effect diagram and ambient temperature of the latex paint of the present invention and the Mg-doped AlPO4 functional coating obtained in Example 2 are shown. DETAILED DESCRIPTION

[0034] The present invention is described in detail below with reference to examples so that those skilled in the art can better understand the present invention, but the present invention is not limited to the following examples.

[0035] The present invention provides a method for preparing a highly emissive magnesium-doped aluminum phosphate passive radiation cooling material, comprising the following specific steps:

[0036] ① Weigh 0.003-0.02 mol of aluminum lactate (Al(C3H5O3)3), 5-20 ml of deionized water, and 10-20 ml of (5-20) wt% hydrochloric acid to promote the dissolution of aluminum lactate. Stir at room temperature for 1-2 hours to completely hydrolyze the aluminum lactate to form solution A.

[0037] ② Weigh a certain amount of MgCl2·6H2O and add it to deionized water to form a 0.1-0.5 mol / L solution B. Mix A and B and stir thoroughly to obtain a solution C, so that the molar ratio of Al to Mg is 1:(0.01-0.05).

[0038] ③ Weigh a certain amount of trimesic acid (BTC) and succinic acid (i.e., butyric acid) into 5-10 ml of dimethylformamide (DMF) and stir thoroughly to form a solution to obtain D. Then, mix C and D and stir thoroughly for 1-2 hours to obtain E. Trimellitic acid and succinic acid prevent aluminum hydroxide precipitation under acidic conditions and can complex with aluminum, enhancing stability. The molar ratio of Al: trimesic acid and succinic acid is 1:(0.2-0.8):(0.2-0.8).

[0039] ④ Weigh a certain amount of pyrophosphoric acid (H4P2O7) and deionized water, stir at room temperature for 1-3 hours to fully dissolve, and prepare solution F. Mix E and F and stir at room temperature for 1-2 hours to obtain solution G, ensuring that the molar ratio of Al to P is (1-1.1):(1-1.1).

[0040] ⑤ Transfer G to a polytetrafluoroethylene microwave reaction vessel and place it in a microwave synthesizer. Maintain the microwave reaction temperature at 100-150°C and a microwave power of 400-800W for 4-8 hours. Microwave hydrothermal heating can achieve more uniform mixing. After the reaction is complete, cool to room temperature to obtain H.

[0041] ⑥ Filter H, and then cross-wash with deionized water and ethanol three times to obtain I.

[0042] ⑦ Place I in a vacuum drying oven at 50-80°C for 3-7 hours to obtain J.

[0043] ⑧Put J in a crucible and place it in a muffle furnace. Heat it from room temperature to 300-400℃ at a rate of 3-5℃ / min and keep it warm for 0.5-1h. A slow heating rate can allow the ethanol to completely evaporate. Heat it to 700-1300℃ at a rate of 6-10℃ / min and keep it warm for 1-3h to obtain K.

[0044] Powder K tablets can be used as passive radiative cooling materials. The tablets have high solar reflectivity, reflecting most sunlight and reducing absorption. They also have high atmospheric window emissivity, allowing the material's internal energy to be exchanged to outer space in the form of infrared radiation, thereby reducing heat and providing cooling.

[0045] ⑨ Weigh a certain amount of latex paint and the prepared K and stir for 3-6 hours to obtain a functional coating with a K content of (10-20) wt%. Apply the coating to the surface of a wood panel for application. The latex paint serves as the solvent, magnesium-doped aluminum phosphate as the filler, and the wood panel as the base. The excellent solar reflectivity and high atmospheric window emissivity of magnesium-doped aluminum phosphate are utilized to lower the temperature, thus achieving cooling.

[0046] Example 1:

[0047] ① Weigh 0.003 mol of aluminum lactate, 5 ml of deionized water, and 10 ml of 10 wt% hydrochloric acid, and stir at room temperature for 1 hour to completely hydrolyze the aluminum lactate to form solution A.

[0048] ② Weigh a certain amount of MgCl2·6H2O and add it to deionized water to form a 0.1 mol / L solution B. Mix A and B and stir thoroughly to form solution C, so that the molar ratio of Al to Mg is 1:0.01.

[0049] ③ Weigh a certain amount of trimesic acid (BTC) and succinic acid (butanedioic acid) into 5 ml of dimethylformamide (DMF) and stir thoroughly to form a solution to obtain D. Then, mix C and D and stir thoroughly for 1 hour to obtain E. The molar ratio of A1: trimesic acid: succinic acid is 1:0.2:0.8.

[0050] ④ Weigh a certain amount of pyrophosphoric acid and deionized water, stir at room temperature for 1 hour to fully dissolve them, and prepare solution F. Mix E and F and stir at room temperature for 1 hour to obtain solution G, ensuring that the molar ratio of Al to P is 1.1:1.

[0051] ⑤ Transfer G to a polytetrafluoroethylene microwave reaction vessel, place the microwave reaction vessel in a microwave synthesizer, maintain the microwave reaction temperature at 100°C and the microwave power at 400W for 4 hours, and cool to room temperature after the reaction is completed to obtain H.

[0052] ⑥ Filter H, and then cross-wash with deionized water and ethanol three times to obtain I.

[0053] ⑦ Place I in a vacuum drying oven at 50°C for 6 h to obtain J.

[0054] ⑧Put J in a crucible and place it in a muffle furnace. Heat it from room temperature to 400℃ at a rate of 3℃ / min, keep it warm for 0.5h, then heat it to 800℃ at a rate of 6℃ / min, keep it warm for 1h to obtain K.

[0055] ⑨ Weigh a certain amount of latex paint and the prepared K, stir for 3 hours to obtain a functional coating with a mass percentage of K of 10 wt%, and apply it on the surface of the wood board for application.

[0056] Example 2:

[0057] ① Weigh 0.01 mol of aluminum lactate, 10 ml of deionized water, and 15 ml of 15 wt% hydrochloric acid, and stir at room temperature for 1 hour to completely hydrolyze the aluminum lactate to form solution A.

[0058] ② Weigh a certain amount of MgCl2·6H2O and add it to deionized water to form a 0.2 mol / L solution B. Mix A and B and stir thoroughly to obtain a solution C, so that the molar ratio of Al to Mg is 1:0.03.

[0059] ③ Weigh a certain amount of trimesic acid (BTC) and succinic acid (butanedioic acid) into 5 ml of dimethylformamide (DMF) and stir thoroughly to form a solution to obtain D. Then, mix C and D and stir thoroughly for 1 hour to obtain E. The molar ratio of A1:trimesic acid:succinic acid is 1:0.5:0.5.

[0060] ④ Weigh a certain amount of pyrophosphoric acid and deionized water, stir at room temperature for 2 hours to fully dissolve them, and prepare solution F. Mix E and F and stir at room temperature for 1 hour to obtain solution G, ensuring that the molar ratio of Al to P is 1:1.

[0061] ⑤ Transfer G to a polytetrafluoroethylene microwave reaction vessel, place the microwave reaction vessel in a microwave synthesizer, maintain the microwave reaction temperature at 120°C and the microwave power at 500W for 5 hours, and cool to room temperature after the reaction is completed to obtain H.

[0062] ⑥ Filter H, and then cross-wash with deionized water and ethanol three times to obtain I.

[0063] ⑦ Place I in a vacuum drying oven at 60°C for 5 h to obtain J.

[0064] ⑧Put J in a crucible and place it in a muffle furnace. Heat it from room temperature to 300℃ at a rate of 4℃ / min, keep it warm for 0.5h, then heat it to 1000℃ at a rate of 7℃ / min, keep it warm for 2h to obtain K.

[0065] ⑨ Weigh a certain amount of latex paint and the prepared K, stir for 4 hours to obtain a functional coating with a mass percentage of K of 15 wt %. Apply the coating on the surface of the wood board for application.

[0066] Example 3:

[0067] ① Weigh 0.015 mol of aluminum lactate, 15 ml of deionized water, and 20 ml of 15 wt% hydrochloric acid, and stir at room temperature for 2 h to completely hydrolyze the aluminum lactate to form solution A.

[0068] ② Weigh a certain amount of MgCl2·6H2O and add it to deionized water to form a 0.4 mol / L solution B. Mix A and B thoroughly and stir to form solution C, so that the molar ratio of Al to Mg is 1:0.04.

[0069] ③ Weigh a certain amount of trimesic acid (BTC) and succinic acid (butanedioic acid) into 10 ml of dimethylformamide (DMF) and stir thoroughly to form a solution to obtain D. Then, mix C and D and stir thoroughly for 2 hours to obtain E. The molar ratio of A1: trimesic acid: succinic acid is 1:0.6:0.4.

[0070] ④ Weigh a certain amount of pyrophosphoric acid and deionized water, stir at room temperature for 3 hours to fully dissolve them, and prepare solution F. Mix E and F and stir at room temperature for 2 hours to obtain solution G, ensuring that the molar ratio of Al to P is 1:1.1.

[0071] ⑤ Transfer G to a polytetrafluoroethylene microwave reaction vessel, place the microwave reaction vessel in a microwave synthesizer, maintain the microwave reaction temperature at 140°C and the microwave power at 600 W for 7 h, and cool to room temperature after the reaction is completed to obtain H.

[0072] ⑥ Filter H, and then cross-wash with deionized water and ethanol three times to obtain I.

[0073] ⑦ Place I in a vacuum drying oven at 70°C for 4 h to obtain J.

[0074] ⑧Put J in a crucible and place it in a muffle furnace. Heat it from room temperature to 400℃ at a rate of 5℃ / min, keep it warm for 1h, then heat it to 1100℃ at a rate of 8℃ / min, keep it warm for 3h to obtain K.

[0075] ⑨ Weigh a certain amount of latex paint and the prepared K, stir for 5 hours, and obtain a functional coating with a mass percentage of K of 20 wt%. Apply the coating on the surface of the wood board for application.

[0076] Example 4:

[0077] ① Weigh 0.02 mol of aluminum lactate, 20 ml of deionized water, and 20 ml of 20 wt% hydrochloric acid, and stir at room temperature for 2 h to completely hydrolyze the aluminum lactate to form solution A.

[0078] ② Weigh a certain amount of MgCl2·6H2O and add it to deionized water to form a 0.5 mol / L solution B. Mix A and B and stir thoroughly to form solution C, so that the molar ratio of Al to Mg is 1:0.05.

[0079] ③ Weigh a certain amount of trimesic acid (BTC) and succinic acid (butanedioic acid) into 10 ml of dimethylformamide (DMF) and stir thoroughly to form a solution to obtain D. Then, mix C and D and stir thoroughly for 2 hours to obtain E. The molar ratio of A1:trimesic acid:succinic acid is 1:0.8:0.2.

[0080] ④ Weigh a certain amount of pyrophosphoric acid and deionized water, stir at room temperature for 2 hours to fully dissolve them, and prepare solution F. Mix E and F and stir at room temperature for 2 hours to obtain solution G, ensuring that the molar ratio of Al to P is 1:1.

[0081] ⑤ Transfer G to a polytetrafluoroethylene microwave reaction vessel, place the microwave reaction vessel in a microwave synthesizer, maintain the microwave reaction temperature at 150°C and the microwave power at 700W for 8 hours, and cool to room temperature after the reaction is completed to obtain H.

[0082] ⑥ Filter H, and then cross-wash with deionized water and ethanol three times to obtain I.

[0083] ⑦ Place I in a vacuum drying oven and dry at 80°C for 3 h to obtain J.

[0084] ⑧Put J in a crucible and place it in a muffle furnace. Heat it from room temperature to 300℃ at a rate of 4℃ / min, keep it warm for 1h, then heat it to 1300℃ at a rate of 9℃ / min, keep it warm for 2h to obtain K.

[0085] ⑨ Weigh a certain amount of latex paint and the prepared K, stir for 6 hours, and obtain a functional coating with a mass percentage of K of 15 wt %. Apply the coating on the surface of the wood board for application.

[0086] Comparative Example 1:

[0087] Undoped aluminum phosphate is a sample prepared under the same conditions except that MgCl2·6H2O is not added.

[0088] ① Weigh 0.01 mol of aluminum lactate, 10 ml of deionized water, and 15 ml of 15 wt% hydrochloric acid, and stir at room temperature for 1 hour to completely hydrolyze the aluminum lactate to form solution A.

[0089] ② Add the same volume of deionized water as in Example 2② to solution A to form solution B. A and B are thoroughly stirred to obtain solution C.

[0090] ③ Weigh a certain amount of trimesic acid (BTC) and succinic acid (butanedioic acid) into 5 ml of dimethylformamide (DMF) and stir thoroughly to form a solution to obtain D. Then, mix C and D and stir thoroughly for 1 hour to obtain E. The molar ratio of A1:trimesic acid:succinic acid is 1:0.5:0.5.

[0091] ④ Weigh a certain amount of pyrophosphoric acid and deionized water, stir at room temperature for 2 hours to fully dissolve them, and prepare solution F. Mix E and F and stir at room temperature for 1 hour to obtain solution G, ensuring that the molar ratio of Al to P is 1:1.

[0092] ⑤ Transfer G to a polytetrafluoroethylene microwave reaction vessel, place the microwave reaction vessel in a microwave synthesizer, maintain the microwave reaction temperature at 120°C and the microwave power at 500W for 5 hours, and cool to room temperature after the reaction is completed to obtain H.

[0093] ⑥ Filter H, and then cross-wash with deionized water and ethanol three times to obtain I.

[0094] ⑦ Place I in a vacuum drying oven at 60°C for 5 h to obtain J.

[0095] ⑧Put J in a crucible and place it in a muffle furnace. Heat it from room temperature to 300℃ at a rate of 4℃ / min, keep it warm for 0.5h, then heat it to 1000℃ at a rate of 7℃ / min, keep it warm for 2h to obtain K.

[0096] ⑨ Weigh a certain amount of latex paint and the prepared K, stir for 3 hours to obtain a functional coating with a mass percentage of K of 15 wt %. Apply the coating on the surface of the wood board for application.

[0097] Figure 1 From the XRD diagram in , it can be seen that a smaller amount of Mg doping has no significant effect on the AlPO4 phase, but it will affect the crystallinity.

[0098] Figure 2 From the XPS graph, we can see that C 1s is the reference peak. The appearance of O1s, P 2p, and Al2p peaks indicates that aluminum phosphate has been successfully prepared. The appearance of Mg1s peak also indicates that magnesium has been successfully incorporated into aluminum phosphate.

[0099] Figure 3 The emission spectrum shows that Mg-doped AlPO4 has excellent atmospheric window emissivity, which can reach 90%.

[0100] Figure 4 It can be seen from the reflection spectrum that Mg-doped AlPO4 has excellent sunlight reflectivity, which can reach 96%.

[0101] from Figure 5 It can be seen from the cooling effect that the temperature of Mg-doped AlPO4 is about 8°C lower than the ambient temperature and 2°C lower than that of undoped aluminum phosphate.

[0102] Can be obtained from Figure 6 It can be seen that the functional latex paint containing Mg-doped AlPO4 can be about 5°C lower than the ambient temperature and about 3°C ​​lower than latex paint.

Claims

1. A method for preparing a magnesium-doped aluminum phosphate passive radiation cooling material, characterized in that: The following steps are involved: S1, mixing aluminum lactate, MgCl2·6H2O, trimesic acid, succinic acid, and pyrophosphoric acid in a solvent, wherein the molar ratio of aluminum lactate to pyrophosphoric acid is (1-1.1):(0.5-0.55), and the molar ratio of aluminum lactate to MgCl2·6H2O is 1:(0.01-0.05), to obtain a precursor solution; S2, hydrothermally treating the precursor solution at 100-150° C. to obtain a reaction solution, washing and drying the product in the reaction solution to obtain magnesium-doped aluminum phosphate powder; S3, calcining the magnesium-doped aluminum phosphate powder at 700-1300° C. for 1-3 hours to obtain a magnesium-doped aluminum phosphate passive radiation refrigeration material.

2. The method for preparing the magnesium-doped aluminum phosphate passive radiation cooling material according to claim 1, characterized in that: S1 obtains the precursor solution as follows: Aluminum lactate, deionized water, and hydrochloric acid are stirred uniformly to obtain a first solution; Dissolving MgCl2·6H2O in deionized water and stirring the obtained solution with the first solution to obtain a second solution; The solution obtained by dissolving trimesic acid and succinic acid in dimethylformamide was stirred evenly with the second solution to obtain a third solution; A solution obtained by dissolving pyrophosphoric acid in deionized water and the third solution are stirred evenly to obtain a precursor solution.

3. The method for preparing the magnesium-doped aluminum phosphate passive radiation cooling material according to claim 2, characterized in that: The mass percentage of hydrochloric acid in the first solution is 5% to 20%, and the ratio of hydrochloric acid to aluminum lactate is (10 to 20) ml: (0.003 to 0.02) mol.

4. The method for preparing the magnesium-doped aluminum phosphate passive radiation cooling material according to claim 1, characterized in that: The molar ratio of aluminum lactate to trimesic acid and succinic acid in S1 is 1:(0.2-0.8):(0.2-0.8).

5. The method for preparing the magnesium-doped aluminum phosphate passive radiation cooling material according to claim 1, characterized in that: The precursor solution described in S2 is hydrothermally treated at 100-150° C. for 4-8 hours to obtain a reaction solution.

6. The method for preparing the magnesium-doped aluminum phosphate passive radiation cooling material according to claim 5, characterized in that: The hydrothermal treatment is carried out in a microwave synthesizer with a microwave power of 400-800W.

7. The method for preparing the magnesium-doped aluminum phosphate passive radiation cooling material according to claim 1, characterized in that: S2: filtering the product in the reaction solution, and then cross-cleaning with deionized water and ethanol to obtain a washed product, and then vacuum drying at 50-80° C. for 3-7 hours to obtain magnesium-doped aluminum phosphate powder.

8. The method for preparing the magnesium-doped aluminum phosphate passive radiation cooling material according to claim 7, characterized in that: S3 is first heated from room temperature to 300-400°C at a rate of 3-5°C / min, kept warm for 0.5-1h, then heated to 700-1300°C at a rate of 6-10°C / min, and calcined at 700-1300°C for 1-3h to obtain magnesium-doped aluminum phosphate passive radiation refrigeration material.

9. A magnesium-doped aluminum phosphate passive radiation cooling material obtained by the preparation method of the magnesium-doped aluminum phosphate passive radiation cooling material according to any one of claims 1 to 8.

10. Use of the magnesium-doped aluminum phosphate passive radiation cooling material according to claim 9 in passive radiation cooling.

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