Universal preparation method of monatomic alloy catalyst

Abstract

The invention discloses a universal preparation method of a monatomic alloy catalyst, which comprises the following steps: placing a surfactant in deionized water, mixing and stirring; dispersing a precursor of a target metal carrier in the monatomic alloy into deionized water, ultrasonically dissolving, adding into the solution, and continuously stirring; washing and centrifuging by using absolute ethyl alcohol, and dispersing a final product into absolute ethyl alcohol for later use; the preparation method comprises the following steps: dispersing a monatomic metal precursor and a surfactant in an organic solvent, and stirring to fully mix; dropwise adding the carrier solution, and continuously stirring to completely volatilize the ethanol; raising the temperature and keeping the temperature for a period of time; and washing and centrifuging the solution by using an organic mixed solvent, and carrying out vacuum drying to obtain a solid product, namely the monatomic alloy. The monatomic alloy catalyst obtained by the invention is uniformly dispersed and is a good catalyst.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation, and in particular relates to a universal preparation method of a single-atom alloy catalyst. Background Art

[0002] In recent years, a large amount of greenhouse gases have led to global warming and climate change, and there is an urgent need to develop renewable energy to achieve energy transformation. Hydrogen energy, as one of the most promising renewable energy sources, has the advantages of high energy density, abundant sources, and only water as a combustion product. There are many ways to produce hydrogen, among which the method of producing hydrogen by electrolysis of water has attracted widespread attention due to its high efficiency, no need to consume fossil energy, and high product purity. As an important green hydrogen production method, hydrogen production by electrolysis of water has the characteristics of being clean, pollution-free, and carbon-free. It is of great significance to achieving global energy transformation and emission reduction goals, and is gradually being developed and promoted. However, the development of efficient and stable electrocatalysts has always been the research focus in this field.

[0003] Single-atom catalysts have attracted widespread attention due to their highest atomic utilization and unique coordination environment. Among them, single-atom alloys, as a unique single-atom catalyst, combine the advantages of alloys and single-atom catalysts. Single-atom alloys refer to a small number of different atoms dispersed on the surface of a metal carrier. These single atoms serve as active sites, and the interaction between them and the carrier makes the catalyst exhibit a unique electronic structure. Single-atom alloy catalysts can expose more active sites and can significantly improve the activity and stability of catalytic reactions. However, since single atoms have high surface energy and are prone to agglomeration during the synthesis process, the synthesis of single-atom alloy catalysts remains a major difficulty.

[0004] For example, Chinese patent application CN107497488A discloses a method for preparing an Au-Pd single-atom alloy catalyst: first, a MOF carrier with an amino group connected to an organic skeleton is synthesized by a hydrothermal method. After a series of operations, Pd exists partially or completely in the form of a single atom on the Au surface to form single-atom alloy nanoparticles. The single-atom alloy has high selectivity in catalyzing the reaction of nitro compounds and aldehydes under mild conditions. For another example, Chinese patent application CN112403493A discloses a method for preparing a PtCu single-atom alloy nanocatalyst and its application. The invention uses CuMgAl ternary hydrotalcite as a precursor, and calcination and reduction are performed to obtain highly dispersed and highly stable supported metal Cu nanoparticles; then PtCl6 2-As a platinum source, Pt is used to replace the surface Cu atoms, and Pt is dispersed on the Cu surface in the form of single atoms to form a PtCu single-atom alloy nanocatalyst. PtCu single-atom alloys show good catalytic performance in the glycerol hydrogenolysis reaction. However, the synthesis technology of the single-atom alloy catalyst is difficult to achieve industrial large-scale preparation due to the complex synthesis reaction and cumbersome steps. On the other hand, the universal preparation of single-atom alloy catalysts has rarely been reported. Therefore, it is of great significance to develop a universal preparation strategy for synthesizing single-atom alloys. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a universal preparation method for single-atom alloy catalysts; the preparation method can achieve the precise construction of a variety of single-atom alloys by changing the type of metal precursor; the single-atom alloy catalysts obtained by the present invention are Bi1Pd, Pt1Pd, Os1Pd, Pt1Ir1Au1Pd single-atom alloys.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A universal preparation method for a single-atom alloy catalyst comprises the following steps:

[0008] 1) placing a surfactant in deionized water and stirring to fully dissolve it to obtain a solution A;

[0009] 2) dispersing the precursor of the metal carrier in deionized water, dissolving it by ultrasonication to obtain a carrier precursor solution, adding the carrier precursor solution to the above solution A, and stirring to complete the reaction;

[0010] 3) centrifuging the solution from step 2) to obtain a solid product, washing the solid product with anhydrous ethanol for multiple times, dispersing the solid product in anhydrous ethanol after washing and centrifugation to obtain a solution B for standby use;

[0011] 4) dispersing the single-atom metal precursor and surfactant to be loaded in an organic solvent, stirring under an inert atmosphere to fully mix them, and obtaining a solution C;

[0012] 5) Add solution B dropwise into solution C, continue stirring to completely evaporate the ethanol, and obtain solution D;

[0013] 6) Raising the temperature of solution D to the reaction temperature to carry out the reaction until the reaction is complete;

[0014] 7) After the reaction is completed, the reaction solution is cooled to room temperature, then washed with an organic mixed solvent and centrifuged, and vacuum dried in a vacuum drying oven to obtain a solid product, which is a single-atom alloy.

[0015] As a further improvement of the technical solution, in step 1), the surfactant is a mixture of ascorbic acid, polyvinyl pyrrolidone, potassium chloride and potassium bromide.

[0016] Preferably, in step 1), the concentration of the surfactant in deionized water is 5 to 50 mg / mL.

[0017] Preferably, in step 1), the stirring temperature is 60-90° C., and the stirring time is 20-60 min.

[0018] As a further improvement of the technical solution, in step 2), the precursor of the metal carrier is selected according to the type of the carrier, and is one of sodium chloropalladate, potassium hypochloroplatinate, iridium chloride, ruthenium chloride, etc.

[0019] Preferably, in step 2), the concentration of the metal salt solution is 2 to 30 mg / mL.

[0020] Preferably, in step 2), the ultrasonic conditions are: 40%-80% of 400W power for 1-5 min.

[0021] Preferably, in step 2), the stirring time is 100-300 min.

[0022] As a further improvement of the technical solution, in step 3), the washing centrifugation refers to adding ethanol to the product after centrifugation, centrifuging again after ultrasonic dispersion, collecting the solid product, and repeating the above process 1-5 times; the conditions for ultrasonic dispersion are: at 40%-100% of 400W power, ultrasonic for 1-10min.

[0023] Preferably, in step 3), the centrifugation condition is 6000-10000 rpm and the time is 5-8 min.

[0024] As a further improvement of the technical solution, in step 4), the type of single-atom metal includes but is not limited to one or more of iridium, osmium, gold, platinum, and bismuth, and the single-atom metal precursor is one of the chloride and nitrate of the metal, and the amount used is less than 4wt% of the metal carrier.

[0025] Preferably, in step 4), the surfactant is a mixture of L-ribose and hexadecyltrimethylammonium chloride.

[0026] Preferably, in step 4), the selected organic solvent is oleylamine, and the concentration of the surfactant is 5 to 15 mg / mL.

[0027] Preferably, in step 4), the inert atmosphere is argon or nitrogen.

[0028] Preferably, in step 4), the stirring temperature is 55-90° C. and the stirring time is 30-90 min.

[0029] As a further improvement of the technical solution, in step 5), the stirring time is 30-120 min.

[0030] As a further improvement of the technical solution, in step 6), the reaction temperature is 150-200° C. and the reaction time is 180-300 min.

[0031] As a further improvement of the technical solution, in step 7), washing centrifugation refers to adding the organic mixed solution to the product after centrifugation, centrifuging again after ultrasonic dispersion, collecting the solid product, and repeating the above process 1-5 times; the conditions for ultrasonic dispersion are: at 40%-100% of 400W power, ultrasonic for 1-10min.

[0032] Preferably, in step 7), the organic mixed solvent is a mixed solution of anhydrous ethanol and n-hexane in a volume ratio of 1:1 to 6:1.

[0033] Preferably, in step 7), the centrifugation condition is 6000-10000 rpm, and the time is 5-8 min.

[0034] Preferably, in step 7), the temperature in the vacuum drying oven is set at 30-60° C. and the vacuum degree is 0.05-0.1 MPa.

[0035] Any range described in the present invention includes the end value and any numerical value between the end values ​​and any sub-range formed by the end value or any numerical value between the end values.

[0036] Unless otherwise specified, all raw materials in the present invention can be purchased from the market, and the equipment used in the present invention can adopt conventional equipment in the relevant field or refer to the existing technology in the relevant field.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The preparation method of the present invention combines wet chemistry with oil phase synthesis, first synthesizes a metal carrier of a single-atom alloy, and then reduces the metal single atom on the carrier through an oil phase reduction process to form a single-atom alloy in which the single atoms are uniformly distributed on the surface of the carrier; by changing the type of the metal carrier precursor, different metal carriers, such as palladium, platinum and other nanoparticles, can be obtained; further, by changing the type of the single-atom metal precursor, different single atoms can be formed on the carrier, and different single-atom alloys can be designed, such as Bi1Pd (Bi is a single atom, P is a single atom) and P is a single atom. d as support), Os1Pd (Os is a single atom, Pd is a support), Pt1Pd (Pt is a single atom, Pd is a support), Pt1Ir1Au1Pd (Pt, Ir, Au are single atoms, Pd is a support), etc.; taking the synthesized Bi1Pd as an example, there is only a Pd peak in the XRD results, and there is no peak related to the Bi system; spherical aberration electron microscopy characterization proves the existence of single atoms on the support; the single atom alloy Pt1Pd catalyst shows excellent performance in the electrocatalytic hydrogen evolution reaction, which is superior to the commercial Pt / C catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0040] Figure 1 shows the X-ray diffraction pattern of the sample prepared in Example 1;

[0041] Figure 2 The spherical aberration electron microscope image of the sample prepared in Example 1 is shown;

[0042] Figure 3 This is the X-ray diffraction pattern of the sample obtained in Example 2;

[0043] Figure 4 This is a transmission electron microscope image of the sample obtained in Example 2;

[0044] Figure 5 This is the spherical aberration electron microscope image of the sample obtained in Example 2;

[0045] Figure 6 This is the element distribution diagram of the sample obtained in Example 2;

[0046] Figure 7 This is the X-ray diffraction pattern of the sample obtained in Example 3;

[0047] Figure 8 This is a transmission electron microscope image of the sample obtained in Example 3;

[0048] Fig. 9 This is the spherical aberration electron microscope image of the sample obtained in Example 3;

[0049] Fig.10 This is the element distribution diagram of the sample obtained in Example 3;

[0050] Fig.11 This is the X-ray diffraction pattern of the sample obtained in Example 4;

[0051] Fig.12 This is the spherical aberration electron microscope image of the sample obtained in Example 4;

[0052] Fig.13 This is the element distribution diagram of the sample obtained in Example 4;

[0053] Fig.14 This is the spherical aberration electron microscope image of the sample prepared in Comparative Example 1. DETAILED DESCRIPTION

[0054] In order to explain the present invention more clearly, the present invention is further described below in conjunction with embodiments. It should be understood by those skilled in the art that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0055] As one aspect of the present invention, a universal preparation method of a single-atom alloy catalyst of the present invention comprises the following steps:

[0056] 1) placing a surfactant in deionized water and stirring to fully dissolve it to obtain a solution A;

[0057] 2) dispersing the precursor of the metal carrier in deionized water, dissolving it by ultrasonication to obtain a carrier precursor solution, adding the carrier precursor solution to the above solution A, and stirring to complete the reaction;

[0058] 3) centrifuging the solution from step 2) to obtain a solid product, washing the solid product with anhydrous ethanol for multiple times, dispersing the solid product in anhydrous ethanol after washing and centrifugation to obtain a solution B for standby use;

[0059] 4) dispersing the single-atom metal precursor and surfactant to be loaded in an organic solvent, stirring under an inert atmosphere to fully mix them, and obtaining a solution C;

[0060] 5) Add solution B dropwise into solution C, continue stirring to completely evaporate the ethanol, and obtain solution D;

[0061] 6) Raising the temperature of solution D to the reaction temperature to carry out the reaction until the reaction is complete;

[0062] 7) After the reaction is completed, the reaction solution is cooled to room temperature, then washed with an organic mixed solvent and centrifuged, and vacuum dried in a vacuum drying oven to obtain a solid product, which is a single-atom alloy.

[0063] According to certain embodiments of the present invention, in step 1), the surfactant is a mixture of ascorbic acid, polyvinyl pyrrolidone, potassium chloride and potassium bromide, which provides a suitable environment for the reduction of the metal salt.

[0064] According to some embodiments of the present invention, in step 1), the concentration of the surfactant in deionized water is 5-50 mg / mL.

[0065] According to some embodiments of the present invention, in step 1), the stirring temperature is 60-90° C. and the stirring time is 20-60 min, so that the solution is evenly mixed.

[0066] According to certain embodiments of the present invention, in step 2), the precursor of the metal carrier is selected according to the type of carrier, and is one of sodium chloropalladate, potassium hypochloroplatinate, iridium chloride or ruthenium chloride.

[0067] According to some embodiments of the present invention, in step 2), the concentration of the metal salt solution is 2-30 mg / mL.

[0068] According to some embodiments of the present invention, in step 2), the ultrasonic conditions are: 40%-80% of 400W power for 1-5 minutes to completely dissolve the metal salt in deionized water.

[0069] According to certain embodiments of the present invention, in step 2), the stirring time is 100-300 min to complete the reaction.

[0070] According to certain embodiments of the present invention, in step 3), the washing centrifugation refers to adding ethanol to the product after centrifugation, centrifuging again after ultrasonic dispersion, collecting the solid product, and repeating the above process 1-5 times; the conditions for ultrasonic dispersion are: at 40%-100% of 400W power, ultrasonic for 1-10min.

[0071] According to certain embodiments of the present invention, in step 3), the centrifugation condition is 6000-10000 rpm, and the time is 5-8 min.

[0072] According to certain embodiments of the present invention, in step 4), the type of single-atom metal includes but is not limited to one of iridium, osmium, gold, platinum, and bismuth, and the single-atom metal precursor is one of the chloride and nitrate of the metal, and the amount used is less than 4wt% of the metal carrier to prevent excessive use of the metal from being dispersed in the form of single atoms on the carrier surface.

[0073] According to certain embodiments of the present invention, in step 4), the surfactant is a mixture of L-ribose and hexadecyltrimethylammonium chloride, which provides a suitable dispersion environment for the metal.

[0074] According to certain embodiments of the present invention, in step 4), the selected organic solvent is oleylamine, and the concentration of the surfactant in the solvent is 5-15 mg / mL.

[0075] According to some embodiments of the present invention, in step 4), the inert atmosphere is argon or nitrogen to prevent oxidation or deterioration of the metal in the air.

[0076] According to certain embodiments of the present invention, in step 4), the stirring temperature is 55-90° C. and the stirring time is 30-90 min, so that the surfactant and the metal salt are completely dispersed in the solution.

[0077] According to certain embodiments of the present invention, in step 5), the stirring time is 30-120 min to allow the ethanol to completely evaporate.

[0078] According to certain embodiments of the present invention, in step 6), the reaction temperature is 150-200° C. and the reaction time is 180-300 min to complete the reaction.

[0079] According to certain embodiments of the present invention, in step 7), washing centrifugation refers to adding the product after centrifugation to an organic mixed solution, centrifuging again after ultrasonic dispersion, collecting the solid product, and repeating the above process 1-5 times; the conditions for ultrasonic dispersion are: 40%-100% of 400W power, ultrasonic for 1-10 minutes, so as to completely remove impurities in the reaction process.

[0080] According to some embodiments of the present invention, in step 7), the organic mixed solvent is a mixed solution of anhydrous ethanol and n-hexane in a volume ratio of 1:1 to 6:1.

[0081] According to certain embodiments of the present invention, in step 7), the centrifugation condition is 6000-10000 rpm and the time is 5-8 min to achieve optimal solid-liquid separation conditions.

[0082] According to certain embodiments of the present invention, in step 7), the temperature in the vacuum drying oven is set at 30-60° C. and the vacuum degree is 0.05-0.1 MPa to prevent oxidation of the product in the air.

[0083] Example 1

[0084] A universal preparation method for a single-atom alloy catalyst comprises the following steps:

[0085] 1) Disperse ascorbic acid, polyvinyl pyrrolidone, potassium chloride and potassium bromide in deionized water at a concentration of 25 mg / mL, and stir at 90°C for 30 min until the solution is uniformly mixed to form solution A;

[0086] 2) Disperse 55 mg of sodium tetrachloropalladate in 5 mL of deionized water, dissolve by ultrasonication, and slowly add it to solution A. Maintain the temperature and continue stirring for 240 min to allow the reaction to complete;

[0087] 3) Centrifuging the reaction solution to obtain a solid product, and then centrifuging it two to three times with anhydrous ethanol, dispersing the final product in anhydrous ethanol to obtain solution B;

[0088] 4) 1.5 mg of bismuth nitrate was selected as the metal precursor of single atomic bismuth, and L-ribose and hexadecyltrimethylammonium chloride were dispersed in oleylamine at a concentration of 8.5 mg / mL. The mixture was stirred at 80° C. for 30 min in a nitrogen atmosphere to fully mix the mixture, thereby obtaining solution C;

[0089] 5) Add solution B dropwise into solution C and continue stirring for 60 min until the ethanol is completely discharged;

[0090] 6) Raise the temperature to 180°C and maintain for 260 min to ensure that the system reacts completely;

[0091] 7) After the reaction is completed, wait for the solution to cool naturally to room temperature, then wash and centrifuge it with a 4:1 mixed solvent of anhydrous ethanol and n-hexane for 2-3 times, and send it to a vacuum drying oven for vacuum drying to obtain a solid product, which is the Bi1Pd single-atom alloy.

[0092] Figure 1 shows the X-ray diffraction pattern of the sample prepared in Example 1;

[0093] Figure 2 The spherical aberration electron microscope image of the sample prepared in Example 1 is shown;

[0094] Example 2

[0095] Example 1 was repeated, with the only difference being that in step 4), 1.5 mg of osmium chloride was selected as a single-atom metal precursor to prepare an Os1Pd single-atom alloy.

[0096] Figure 3 The X-ray diffraction pattern of the sample obtained in this Example 2 proves the formation of single-atom alloy;

[0097] Figure 4 This is a transmission electron microscope image of the sample obtained in Example 2;

[0098] Figure 5 This is a spherical aberration electron microscope image of the sample obtained in Example 2, proving the formation of single atoms;

[0099] Figure 6 This is the element distribution diagram of the sample prepared in Example 2.

[0100] Example 3

[0101] Example 1 was repeated, with the only difference being that in step 4), 1.5 mg of potassium tetrachloroplatinate was selected as a single-atom metal precursor to prepare a Pt1Pd single-atom alloy.

[0102] Figure 7 The X-ray diffraction pattern of the sample obtained in Example 3 proves the formation of single-atom alloy;

[0103] Figure 8 This is a transmission electron microscope image of the sample obtained in Example 3;

[0104] Fig. 9 This is a spherical aberration electron microscope image of the sample obtained in Example 3, proving the formation of single atoms;

[0105] Fig.10 This is the element distribution diagram of the sample prepared in Example 3.

[0106] Example 4

[0107] Example 1 was repeated, except that in step 4), 0.5 mg potassium tetrachloroplatinate and 0.5 mg

[0108] Iridium chloride and 0.5 mg of gold chloride were used as single-atom metal precursors to prepare a ternary single-atom alloy of Pt1Ir1Au1Pd.

[0109] Fig.11 The X-ray diffraction pattern of the sample obtained in Example 4 proves the formation of single-atom alloy;

[0110] Fig.12 This is a spherical aberration electron microscope image of the sample obtained in Example 4, proving the formation of single atoms;

[0111] Fig.13 This is the element distribution diagram of the sample prepared in Example 4.

[0112] Comparative Example 1

[0113] Example 1 was repeated, except that the addition amount of potassium tetrachloroplatinate was 3.0 mg. Characterization by spherical aberration electron microscopy showed that an obvious shell layer was formed on the surface of the cube, thereby obtaining a core-shell Pd@Pt catalyst.

[0114] It can be seen that the addition amount of metal precursor salt is crucial for the synthesis of single atom alloys.

[0115] Fig.14 The spherical aberration electron microscope image of the sample prepared in this comparative example 1 proves the core-shell structure of the alloy;

[0116] In summary, the present invention provides a universal preparation method for a single-atom alloy catalyst, in which metal precursors, temperature, reaction atmosphere, solution volume, etc. are coordinated and cooperated with each other to form a complete technical solution, so that the single-atom alloy catalyst required by the present invention can be obtained.

[0117] Obviously, the above embodiments and comparative examples of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the embodiments here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A universal preparation method for a single-atom alloy catalyst, characterized in that: The steps include: 1) placing a surfactant in deionized water and stirring to fully dissolve it to obtain a solution A; 2) dispersing the precursor of the metal carrier in deionized water, dissolving it by ultrasonication to obtain a carrier precursor solution, adding the carrier precursor solution to the above solution A, and stirring to complete the reaction; 3) centrifuging the solution from step 2) to obtain a solid product, washing the solid product with anhydrous ethanol for multiple times, dispersing the solid product in anhydrous ethanol after washing and centrifugation to obtain a solution B for standby use; 4) dispersing the single-atom metal precursor and surfactant to be loaded in an organic solvent, stirring under an inert atmosphere to fully mix them, and obtaining a solution C; 5) Add solution B dropwise into solution C, continue stirring to completely evaporate the ethanol, and obtain solution D; 6) Raising the temperature of solution D to the reaction temperature to carry out the reaction until the reaction is complete; 7) After the reaction is completed, the reaction solution is cooled to room temperature, then washed with an organic mixed solvent and centrifuged, and vacuum dried in a vacuum drying oven to obtain a solid product, which is a single-atom alloy.

2. The universal preparation method according to claim 1, characterized in that: In step 1), the surfactant is a mixture of ascorbic acid, polyvinyl pyrrolidone, potassium chloride and potassium bromide.

3. The universal preparation method according to claim 1, characterized in that: In step 1), the concentration of the surfactant in deionized water is 5 to 50 mg / mL.

4. The universal preparation method according to claim 1, characterized in that: In step 1), the stirring temperature is 60-90° C. and the stirring time is 20-60 min.

5. The universal preparation method according to claim 1, characterized in that: In step 2), the precursor of the metal carrier is one of sodium chloropalladate, potassium hypochloroplatinate, iridium chloride or ruthenium chloride.

6. The universal preparation method according to claim 1, characterized in that: In step 2), the concentration of the metal salt solution is 2 to 30 mg / mL; Preferably, in step 2), the ultrasonic conditions are: 40%-80% of 400W power for 1-5min; Preferably, in step 2), the stirring time is 100-300 min.

7. The universal preparation method according to claim 1, characterized in that: In step 3), the washing centrifugation refers to adding ethanol to the product after centrifugation, centrifuging again after ultrasonic dispersion, collecting the solid product, and repeating the above process 1-5 times; the conditions for ultrasonic dispersion are: at 40%-100% of 400W power, ultrasonic for 1-10min; Preferably, in step 3), the centrifugation condition is 6000-10000 rpm and the time is 5-8 min.

8. The universal preparation method according to claim 1, characterized in that: In step 4), the type of the single-atom metal includes but is not limited to one or more of iridium, osmium, gold, platinum, and bismuth, and the single-atom metal precursor is one of a chloride and a nitrate of the metal, and the amount used is less than 4wt% of the metal carrier; Preferably, in step 4), the surfactant is a mixture of L-ribose and hexadecyltrimethylammonium chloride; Preferably, in step 4), the selected organic solvent is oleylamine, and the concentration of the surfactant is 5 to 15 mg / mL; Preferably, in step 4), the inert atmosphere is argon or nitrogen; Preferably, in step 4), the stirring temperature is 55-90° C. and the stirring time is 30-90 min.

9. The universal preparation method according to claim 1, characterized in that: In step 5), the stirring time is 30-120 min; Preferably, in step 6), the reaction temperature is 150-200° C. and the reaction time is 180-300 min.

10. The universal preparation method according to claim 1, characterized in that: In step 7), washing centrifugation refers to adding the organic mixed solution to the product after centrifugation, centrifuging again after ultrasonic dispersion, collecting the solid product, and repeating the above process 1-5 times; the conditions for ultrasonic dispersion are: at 40%-100% of 400W power, ultrasonic for 1-10min; Preferably, in step 7), the organic mixed solvent is a mixed solution of anhydrous ethanol and n-hexane in a volume ratio of 1:1 to 6:1; Preferably, in step 7), the centrifugation condition is 6000-10000 rpm, time 5-8 min; Preferably, in step 7), the temperature in the vacuum drying oven is set at 30-60° C. and the vacuum degree is 0.05-0.1 MPa.

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