Metal organic framework material with high laser absorptivity as well as preparation method and application of metal organic framework material

Abstract

The invention relates to a metal organic framework material with high laser absorptivity as well as a preparation method and application of the metal organic framework material. The metal organic framework material is a crystalline porous material formed by interaction of a hydrotalcite-like-carbon quantum dot composite nano additive, metal ions and an organic ligand. The preparation method comprises the following steps: 1, sequentially adding hydrotalcite-like compounds and carbon quantum dots into deionized water, and carrying out ultrasonic treatment to obtain a first product; 2, adding the first product into deionized water containing an organic ligand for ultrasonic treatment; 3, fully mixing the mixed solution with an ionic water solution containing metal salt; 4, adding a sodium borohydride aqueous solution into the mixed solution, and standing for reaction; 5, after the reaction is finished, removing impurities; and 6, carrying out gradient heating and drying to obtain the metal organic framework material. The invention has the following advantages: on one hand, particle size adjustment is realized, and laser absorptivity is improved; on the other hand, the decomposition and ionization efficiency is improved, the ablation depth and the ablation mass of the single-pulse laser are small, and the generated specific impulse is high.

Description

Technical Field

[0001] The present invention belongs to the field of laser propulsion technology for space satellite propulsion, and relates to a metal organic framework material with high laser absorption rate, high decomposition and ionization efficiency and a preparation method thereof, and specifically relates to a metal organic framework material with high laser absorption rate and a preparation method and application thereof. Background Art

[0002] Laser propulsion technology utilizes pulsed lasers to ablate a working fluid, creating a high-speed, back-jetting laser plasma plume through melting, vaporization, and ionization, thereby generating thrust. Laser propulsion fluids are categorized as either liquid or solid. Liquid working fluids can achieve a large impulse coupling coefficient, but their specific impulse is very small. Furthermore, during the laser ablation process, droplet splashing can occur, significantly reducing the laser ablation efficiency. Therefore, improving laser propulsion performance requires the use of solid working fluids.

[0003] Solid working fluids have the advantages of easy molding, simple structure and reliable operation. Existing solid working fluids can generally be divided into polymer materials and single-element materials such as copper, iron, zinc and carbon. Polymers have low thermal conductivity, low melting point and low ablation threshold, which produces a large impulse coupling coefficient. However, their absorption coefficient is low, and the single-pulse ablation depth and ablation mass are large, resulting in a low specific impulse of polymer working fluids. On the other hand, single-element materials have the advantages of small ablation mass and easy formation of plasma during laser ablation, so a large specific impulse can be obtained, but the impulse coupling coefficient generated is small. In order to improve the laser absorption coefficient and comprehensive micro-propulsion performance of solid working fluids, metal nanoparticles or carbon nanoparticles are usually incorporated into polymers for physical mixing. However, this physical mixing method has problems such as particle agglomeration and uneven doping, which limits the further improvement of propulsion performance, thereby limiting the application of solid working fluids in laser propulsion technology.

[0004] Metal-organic framework (MOFs) compound materials are a type of porous crystalline material with a periodic network structure formed by coordination self-assembly of metal nodes and organic ligands. They achieve atomic-level mixing of metals and polymers, thereby eliminating the laser ablation problem caused by traditional physical mixing methods and improving the laser propulsion performance of solid working fluids.

[0005] While no fully matching Chinese patent applications have been found, some related research areas involve the application of metal-organic frameworks (MOFs) in light-related fields. For example, a new photosensitive material designed by the He Dalin team at the First Affiliated Hospital of Xi'an Jiaotong University and the Zhang Penghui team at the Institute of Oncology and Basic Medicine of the Chinese Academy of Sciences encapsulates a porphyrin-based photosensitizer and a ferroptosis-inducing agent within a MOF. This resulted in the development of a nanocarrier, HAFeR, that synergistically activates ferroptosis and photodynamic therapy. Due to its higher photon energy and enhanced absorption, HAFeR can generate more ROS and induce cell apoptosis when irradiated by 450nm laser light compared to 630nm laser light.

[0006] Based on this, research and development of MOFs with higher laser absorption rate, higher decomposition and ionization efficiency and lower single-pulse ablation mass, so as to obtain laser propulsion solid working fluid with higher specific impulse, is of great significance to improving laser propulsion performance and is also a technical problem that needs to be solved urgently. Summary of the Invention

[0007] The purpose of the present invention is: The purpose of the present invention is to overcome the shortcomings of the existing MOFs preparation process, which fails to fully consider the influence mechanism of its light absorption characteristics on laser ablation characteristics and fails to combine it with key processes such as decomposition and ionization related to laser propulsion performance, resulting in low specific impulse. A metal-organic framework material with improved laser absorption rate and decomposition and ionization efficiency is provided. Through the design of material structure and composition, efficient absorption and more full utilization of laser are achieved; at the same time, a preparation method of the material is provided to ensure the repeatability and stability of the material; in addition, the application of the material in laser-related fields is clarified to expand its application range.

[0008] The technical solution of the present invention: A high laser absorption metal organic framework material is a crystalline porous material formed by the interaction of hydrotalcite-carbon quantum dot composite nano-additives, metal ions and organic ligands; The ratio range of the three is: the amount of hydrotalcite added is 0.2%-1.2% of the total mass of organic ligands and metal ions, the amount of carbon quantum dots added is 30%-60% of the amount of hydrotalcite added, and the molar ratio of organic ligands to metal ions is 35-60:1; The metal ion is a metal salt; the organic ligand is a heterocyclic aromatic organic compound; The metal salt includes one or more of metal nitrates, hydrated nitrates, hydrated chlorides, sulfates, and acetates; the metal is selected from one of cobalt and zinc; The organic ligand is one or more of 2-methylimidazole, benzimidazole, nitroimidazole, and imidazole-2-carboxaldehyde; The hydrotalcite-like compound is at least one of a cobalt-aluminum hydrotalcite-like compound and a zinc-aluminum hydrotalcite-like compound; The synthesis method of the cobalt-aluminum hydrotalcite is: ① Prepare 600 mL of solution A: an aqueous solution containing 58.2 g of Co(NO3)2·6H2O and 37.5 g of Al(NO3)3·9H2O, and 600 mL of solution B: an aqueous solution containing 48 g of sodium hydroxide and 10.6 g of sodium carbonate; ② Slowly add the two into a four-necked flask, stirring continuously and maintaining argon protection. The pH value of the solution is maintained at around 8.5 during the entire synthesis process; ③ After stirring the mixture at 30°C for 1 hour, transfer it to a hydrothermal reactor and maintain it at 90°C for 12 hours. Then, wash it repeatedly with deionized water until the pH value is neutral. ④ Place the sample in an oven at 100℃ and dry for 12 hours until it reaches constant weight, then grind it into powder.

[0009] The synthesis method of the zinc-aluminum hydrotalcite is: ① Prepare 600 mL of solution A: an aqueous solution containing 59.5 g Zn(NO3)2·6H2O and 37.5 g Al(NO3)3·9H2O, and 600 mL of solution B: an aqueous solution containing 48 g sodium hydroxide and 10.6 g sodium carbonate; ② Slowly add the two into a four-necked flask, stirring continuously and maintaining argon protection. The pH value of the solution is maintained at around 8.5 during the entire synthesis process; ③ After stirring the mixture at 30°C for 1 hour, transfer it to a hydrothermal reactor and maintain it at 90°C for 12 hours. Then, wash it repeatedly with deionized water until the pH value is neutral. ④ Place the sample in an oven at 100℃ and dry for 12 hours until it reaches constant weight, then grind it into powder.

[0010] The synthesis method of the carbon quantum dots: The amount of carbon quantum dots added is 30%-60% of the amount of hydrotalcite-like substances added.

[0011] ① Weigh 0.1g dopamine hydrochloride and 0.1g o-phenylenediamine and dissolve them in 15mL ethanol, then transfer them to a hydrothermal reactor and react at 160-180℃ for 12 hours; ② After cooling to room temperature, centrifugation and washing with ethanol, further purification was performed using a dialysis membrane for 2 days, and carbon quantum dots were obtained after freeze-drying.

[0012] A method for preparing a metal-organic framework material with high laser absorptivity comprises the following steps: ① Weighing a hydrotalcite-like substance, adding deionized water, ultrasonically treating it, then adding carbon quantum dots and continuing ultrasonication to adsorb the carbon quantum dots on the surface of the hydrotalcite-like substance to obtain a hydrotalcite-carbon quantum dot composite nano-additive mixture; ② Dissolve the organic ligand in deionized water, then add the hydrotalcite-carbon quantum dot composite nano-additive mixture from step 1, and perform ultrasonic treatment while controlling the temperature at 15°C-40°C. The purpose of controlling the temperature at 15°C-40°C is to avoid local overheating that may cause desorption of carbon quantum dots. ③ Dissolve the metal salt in ionized water and add it to the above mixture in three gradient steps. Let it stand for 30 minutes after each addition. Gradient release of hydrotalcite-carbon quantum dot composite nano-additive , regulating the nucleation and crystallization growth rates of MOFs and inhibiting the disordered growth of crystals; ④ Add sodium borohydride aqueous solution to the above mixture, the mass of sodium borohydride added is 0.1%-1% of the mass of the metal salt added, and let it stand at room temperature and react for 24 hours in the dark without stirring; sodium borohydride reduces some metal ions, enhances the localized surface plasmon resonance effect, and synergistically improves the absorption and utilization ability of laser light; ⑤ After the reaction is completed, wash with deionized water containing 0.5% EDTA and methanol three times each; EDTA targets and complexes free metal ions, and methanol removes unreacted ligands and residual raw materials; ⑥ Dry the product in a vacuum drying oven at a gradient temperature: first at 50°C for 2 hours, then at 80°C for 20 hours, and finally at 120°C for 2 hours. This is to gradually remove physically adsorbed water, coordinated water, and pore solvent to prevent framework collapse.

[0013] The present invention overcomes the shortcomings of the existing MOFs working fluid preparation process in laser propulsion, which fails to fully consider the influence mechanism of the working fluid's light absorption characteristics on the ablation characteristics, fails to combine it with key processes such as decomposition and ionization related to propulsion performance, and has a low working fluid specific impulse.

[0014] Compared with the existing technology, it has the following advantages: the introduction of hydrotalcite-carbon quantum dot composite nano-additives in the preparation process of metal-organic framework materials can, on the one hand, achieve particle size adjustment and improve laser absorption rate, up to 95.8%; on the other hand, it improves decomposition and ionization efficiency, and the single-pulse laser ablation depth and ablation mass are small, resulting in a high specific impulse, with the highest specific impulse reaching 1094s.

[0015] It has been well-established that the crystallization process of metal-organic framework materials is synergistically regulated by the nucleation and growth dynamics, which together determine the final crystal particle size. It is worth noting that in conventional synthesis, nucleation and growth often proceed simultaneously. This study innovatively proposes to achieve precise control of crystal particle size by spatially separating the nucleation and growth stages. Specifically, unlike the traditional MOFs synthesis process, the present invention pre-introduces a hydrotalcite-carbon quantum dot composite nano-additive into the system. The additive can serve as a slow-release carrier for metal ions. The released metal ions coordinate with the organic ligands in the system to form metal-organic clusters. These clusters act as highly active crystal seeds to effectively guide the subsequent epitaxial growth of MOFs crystals. By systematically regulating the amount of hydrotalcite introduced, precise control of the MOFs crystal particle size can be achieved. As a solid working fluid, changes in the particle size of metal-organic framework materials will affect the laser absorptivity by regulating light scattering, absorption paths and resonance effects.

[0016] On the other hand, carbon quantum dots (CQDs) are a class of carbon nanoparticles with diameters under 10 nm. Their surfaces are rich in oxygen-containing functional groups, offering excellent water solubility, photothermal conversion, and catalytic properties. Hydrotalcite-like materials have a positively charged surface. Carbon quantum dots rich in oxygen-containing functional groups within a certain mass range (adding too many CQDs will hinder the release of metal ions, while adding too few will have little effect) are adsorbed onto the surface of the hydrotalcite-like materials, forming a hydrotalcite-carbon quantum dot nanocomposite additive. Combined with the unique interlayer exchangeable anion function of the hydrotalcite-like materials, the reaction pathway can be regulated in a laser-induced high-temperature plasma environment, accelerating the decomposition and ionization of the working fluid through catalysis. This process significantly shortens the ignition delay time of the working fluid, promotes the instantaneous burst release of a large amount of plasma, and achieves improved decomposition and ionization efficiency.

[0017] By comprehensively using the above technical means, a MOFs working fluid with higher laser absorption rate, higher decomposition and ionization efficiency and lower single-pulse ablation mass was prepared, thereby achieving higher specific impulse. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention has 5 drawings, wherein Figure 5 It can also be used as an illustration of the abstract of the specification.

[0019] Figure 1 A scanning electron microscope image of the metal organic framework material prepared in Example 4; Figure 2 .Schematic diagram of the structure for measuring laser absorptivity using the integrating sphere method; Figure 3 A pendulum device for single-pulse laser propulsion applications and performance testing of solid working fluids; Figure 4 . The single pulse laser ablation pit morphology of Example 2; Figure 5 . This is the single-pulse laser ablation pit profile analysis of Example 2. DETAILED DESCRIPTION

[0020] The embodiments of the present invention are further described below with reference to the accompanying drawings: A metal-organic framework material with high laser absorption rate is a crystalline porous material formed by the interaction of hydrotalcite-carbon quantum dot composite nano-additives, metal ions and organic ligands; The ratio of the three is as follows: the amount of hydrotalcite added is 0.2%-1.2% of the total mass of the organic ligand and the metal ion, and the molar ratio of the organic ligand to the metal ion is 35-60:1; The metal ion is a metal salt; the organic ligand is a heterocyclic aromatic organic compound; The metal salt includes one or more of metal nitrates, hydrated nitrates, hydrated chlorides, sulfates, and acetates; the metal is selected from one of cobalt and zinc; The organic ligand is one or more of 2-methylimidazole, benzimidazole, nitroimidazole, and imidazole-2-carboxaldehyde; The hydrotalcite-like compound is at least one of a cobalt-aluminum hydrotalcite-like compound and a zinc-aluminum hydrotalcite-like compound; and is characterized in that: The synthesis method of the cobalt-aluminum hydrotalcite is: Prepare 600 mL of solution A: an aqueous solution containing 58.2 g of Co(NO3)2·6H2O and 37.5 g of Al(NO3)3·9H2O, and 600 mL of solution B: an aqueous solution containing 48 g of sodium hydroxide and 10.6 g of sodium carbonate.

[0021] ① Slowly add the two into a four-necked flask, and continue stirring under argon protection. The pH value of the solution is maintained at around 8.5 during the entire synthesis process; ② After stirring the mixture at 30°C for 1 hour, transfer it to a hydrothermal reactor and maintain it at 90°C for 12 hours. Then, wash it repeatedly with deionized water until the pH value reaches neutral. ③ Place the sample in an oven at 100℃ and dry for 12 hours until it reaches constant weight, then grind it into powder.

[0022] The synthesis method of the zinc-aluminum hydrotalcite is: Prepare 600 mL of solution A: an aqueous solution containing 59.5 g of Zn(NO3)2·6H2O and 37.5 g of Al(NO3)3·9H2O, and 600 mL of solution B: an aqueous solution containing 48 g of sodium hydroxide and 10.6 g of sodium carbonate.

[0023] ① Slowly add the two into a four-necked flask, and continue stirring under argon protection. The pH value of the solution is maintained at around 8.5 during the entire synthesis process; ② After stirring the mixture at 30°C for 1 hour, transfer it to a hydrothermal reactor and maintain it at 90°C for 12 hours. Then, wash it repeatedly with deionized water until the pH value reaches neutral. ③ Place the sample in an oven at 100℃ and dry for 12 hours until it reaches constant weight, then grind it into powder.

[0024] The synthesis method of the carbon quantum dots is: The amount of carbon quantum dots added is 30%-60% of the amount of hydrotalcite-like substances added.

[0025] ① Weigh 0.1g dopamine hydrochloride and 0.1g o-phenylenediamine and dissolve them in 15mL ethanol, then transfer them to a hydrothermal reactor and react at 160℃-180℃ for 12 hours; ② After cooling to room temperature, centrifugation and washing with ethanol, further purification was performed using a dialysis membrane for 2 days, and carbon quantum dots were obtained after freeze-drying.

[0026] Example 1 1. Weigh 29.5 mg of cobalt-aluminum hydrotalcite (0.50% of the total weight of the organic ligand and metal salt) and add 5 mL of deionized water. After ultrasonic treatment for 10 minutes, add 16.2 mg of carbon quantum dots (55% of the weight of the hydrotalcite). Continue ultrasonication for 15 minutes to allow the carbon quantum dots to adsorb on the surface of the cobalt-aluminum hydrotalcite to obtain a cobalt-aluminum hydrotalcite-carbon quantum dot composite nano-additive mixture. 2. Dissolve 5.45 g of 2-methylimidazole in 35 mL of deionized water, then add the cobalt-aluminum hydrotalcite-carbon quantum dot composite nano-additive mixture from step 1 and ultrasonicate for 10 minutes at 25°C. 3. Dissolve 0.45g of cobalt nitrate hexahydrate in 6mL of deionized water and add it to the mixture in three gradient steps, 30 minutes apart. Let it stand for 10 minutes after each addition. The molar ratio of organic ligand to metal salt is 43:1. 4. Add 2 mL of sodium borohydride aqueous solution (2 mg / mL) to the above mixture and allow to react at room temperature without stirring for 24 hours in the dark. 5. After the reaction is complete, wash with deionized water containing 0.5% EDTA and methanol three times each; 6. Dry the product in a vacuum drying oven at a gradient temperature: first heat at 50°C for 2 h, then heat at 80°C for 20 h, and finally, heat at 120°C for 2 h.

[0027] Example 2 1. Weigh 20.8 mg of zinc-aluminum hydrotalcite (0.37% of the total weight of the organic ligand and metal salt) and add 4 mL of deionized water. After ultrasonic treatment for 10 minutes, add 10.4 mg of carbon quantum dots (50% of the weight of the hydrotalcite). Continue ultrasonication for 15 minutes to allow the carbon quantum dots to adsorb on the surface of the zinc-aluminum hydrotalcite to obtain a zinc-aluminum hydrotalcite-carbon quantum dot composite nano-additive mixture. 2. Dissolve 5.45 g of benzimidazole in 16 mL of deionized water, then add the zinc-aluminum hydrotalcite-carbon quantum dot composite nano-additive mixture from step 1 and ultrasonicate for 10 minutes at 35°C. 3. Dissolve 0.18g of zinc chloride hydrate in 6mL of deionized water and add it to the above mixture in three gradient additions (30min intervals). Let it stand for 10min after each addition. The molar ratio of organic ligand to metal salt is 53:1. 4. Add 0.5 mL of sodium borohydride aqueous solution (2 mg / mL) to the above mixture and allow to react at room temperature without stirring for 24 hours in the dark. 5. After the reaction is complete, wash with deionized water containing 0.5% EDTA and methanol three times each; 6. Dry the product in a vacuum drying oven at a gradient temperature: first heat at 50°C for 2 h, then heat at 80°C for 20 h, and finally, heat at 120°C for 2 h.

[0028] Example 3 1. Pre-weigh 60.5 mg of cobalt-aluminum hydrotalcite (1.08% of the total weight of the organic ligand and metal salt), add 5 mL of deionized water, and sonicate for 10 minutes. Then, add 24.2 mg of carbon quantum dots (40% of the weight of the hydrotalcite), and continue sonicating for 15 minutes to allow the carbon quantum dots to adsorb on the surface of the cobalt-aluminum hydrotalcite to obtain a cobalt-aluminum hydrotalcite-carbon quantum dot composite nano-additive mixture. 2. Dissolve 5.45 g of nitroimidazole in 35 mL of deionized water, then add the cobalt-aluminum hydrotalcite-carbon quantum dot composite nano-additive mixture from step 1 and ultrasonicate for 10 minutes at 20°C. 3. Dissolve 0.16g of cobalt sulfate in 6mL of deionized water and add it to the above mixture in three gradient additions with an interval of 30 minutes. Let it stand for 10 minutes after each addition. The molar ratio of organic ligand to metal salt is 47:1. 4. Add 0.5 mL of sodium borohydride aqueous solution (2 mg / mL) to the above mixture and allow to react at room temperature without stirring for 24 hours in the dark. 5. After the reaction is complete, wash with deionized water containing 0.5% EDTA and methanol three times each; 6. Dry the product in a vacuum drying oven at a gradient temperature: first heat at 50°C for 2 h, then heat at 80°C for 20 h, and finally, heat at 120°C for 2 h.

[0029] Example 4 1. Weigh 29.1 mg of cobalt-aluminum hydrotalcite (0.51% of the total weight of the organic ligand and metal salt) and add 5 mL of deionized water. After ultrasonic treatment for 10 minutes, add 16.0 mg of carbon quantum dots (55% of the weight of the hydrotalcite) and continue ultrasonication for 15 minutes to allow the carbon quantum dots to adsorb on the surface of the cobalt-aluminum hydrotalcite to obtain a cobalt-aluminum hydrotalcite-carbon quantum dot composite nano-additive mixture. 2. Dissolve 5.45 g of imidazole-2-carboxaldehyde in 35 mL of deionized water, then add the cobalt-aluminum hydrotalcite-carbon quantum dot composite nano-additive mixture from step 1 and ultrasonicate for 10 minutes at 28°C. 3. Dissolve 0.31g of cobalt nitrate hexahydrate in 6mL of deionized water and add it to the above mixture in three gradient additions with an interval of 30 minutes. Let it stand for 10 minutes after each addition. The molar ratio of organic ligand to metal salt is 53:1. 4. Add 1 mL of sodium borohydride aqueous solution (2 mg / mL) to the above mixture and allow to react at room temperature without stirring for 24 hours in the dark. 5. After the reaction is complete, wash with deionized water containing 0.5% EDTA and methanol three times each; 6. Dry the product in a vacuum drying oven at a gradient temperature: first heat at 50°C for 2 h, then heat at 80°C for 20 h, and finally, heat at 120°C for 2 h.

[0030] Example 5 1. Weigh 20.8 mg of zinc-aluminum hydrotalcite (0.37% of the total weight of the organic ligand and metal salt) and add 4 mL of deionized water. After ultrasonic treatment for 10 minutes, add 10.4 mg of carbon quantum dots (50% of the weight of the hydrotalcite). Continue ultrasonication for 15 minutes to allow the carbon quantum dots to adsorb on the surface of the zinc-aluminum hydrotalcite to obtain a zinc-aluminum hydrotalcite-carbon quantum dot composite nano-additive mixture. 2. Dissolve 5.45 g of benzimidazole in 16 mL of deionized water, then add the zinc-aluminum hydrotalcite-carbon quantum dot composite nano-additive mixture from step 1 and ultrasonicate for 10 minutes at 35°C. 3. Dissolve 0.18g zinc nitrate in 6mL of deionized water and add it to the above mixture in three gradient additions with an interval of 30 minutes. Let it stand for 10 minutes after each addition. The molar ratio of organic ligand to metal salt is 49:1. 4. Add 0.5 mL of sodium borohydride aqueous solution (2 mg / mL) to the above mixture and allow to react at room temperature without stirring for 24 hours in the dark. 5. After the reaction is complete, wash with deionized water containing 0.5% EDTA and methanol three times each; 6. Dry the product in a vacuum drying oven at a gradient temperature: first heat at 50°C for 2 h, then heat at 80°C for 20 h, and finally, heat at 120°C for 2 h.

[0031] Example 6 1. Weigh 20.8 mg of zinc-aluminum hydrotalcite (0.37% of the total weight of the organic ligand and metal salt) and add 4 mL of deionized water. After ultrasonic treatment for 10 minutes, add 10.4 mg of carbon quantum dots (50% of the weight of the hydrotalcite). Continue ultrasonication for 15 minutes to allow the carbon quantum dots to adsorb on the surface of the zinc-aluminum hydrotalcite to obtain a zinc-aluminum hydrotalcite-carbon quantum dot composite nano-additive mixture. 2. Dissolve 5.45 g of benzimidazole in 16 mL of deionized water, then add the zinc-aluminum hydrotalcite-carbon quantum dot composite nano-additive mixture from step 1 and ultrasonicate for 10 minutes at 35°C. 3. Dissolve 0.18g of zinc acetate in 6mL of deionized water and add it to the above mixture in three gradient additions (30min intervals). Let it stand for 10min after each addition. The molar ratio of organic ligand to metal salt is 47:1. 4. Add 0.5 mL of sodium borohydride aqueous solution (2 mg / mL) to the above mixture and allow to react at room temperature without stirring for 24 hours in the dark. 5. After the reaction is complete, wash with deionized water containing 0.5% EDTA and methanol three times each; 6. Dry the product in a vacuum drying oven at a gradient temperature: first heat at 50°C for 2 h, then heat at 80°C for 20 h, and finally, heat at 120°C for 2 h.

[0032] Comparative Example 1 The preparation method is the same as that of Example 2, except that step 1 is omitted, that is, the cobalt-aluminum hydrotalcite-carbon quantum dot composite nano-additive is not added.

[0033] Comparative Example 2 The preparation method is the same as that of Example 3, except that 83.9 mg of cobalt-aluminum hydrotalcite is weighed in advance, accounting for 1.50% of the total mass of the organic ligand and the metal salt.

[0034] Comparative Example 3 The preparation method is the same as that of Example 3, except that in step 2, the temperature is controlled at 50°C.

[0035] Comparative Example 4 The preparation method is the same as that of Example 3, except that in step 1, 42.3 mg of carbon quantum dots are added.

[0036] The particle size of the metal organic framework material prepared above was tested, and the average particle size of the metal organic framework material was determined by measuring about 300 crystals in 5 scanning electron microscope images using ImageJ software.

[0037] The prepared metal-organic framework material was pressed into sheets using a hydraulic press and used as a solid working fluid for laser propulsion for application and performance testing.

[0038] The laser absorption rate of solid working medium is measured. Figure 2 As shown, the integrating sphere method is used to measure the absorption rate of a solid working medium to a laser beam having a wavelength of 1064 nm. The measurement system includes a laser 1, a pinhole aperture 2, an attenuation plate 3, a beam splitter 4, an integrating sphere 5, a solid working medium 6, a photodetector 7, an energy meter 8, and a display screen 9. The laser 1 is used to emit a laser beam. The solid working medium 6 is placed on the wall of the integrating sphere 5. The pinhole aperture 2 and the attenuation plate 3 are used to adjust the beam diameter and energy. The beam splitter 4 is used to split the laser beam. Weak light is used by the energy meter 8 to monitor the laser energy. Strong light passes through the pinhole aperture 2 and enters the integrating sphere 5 to irradiate the solid working medium 6. The reflected laser light is reflected multiple times by the inner wall, forming a uniform energy distribution on the inner wall of the integrating sphere. The photodetector 7 on the wall of the integrating sphere 5 monitors the change in the intensity of the reflected light on the target surface. This change is recorded by the data acquisition system consisting of the host computer 10 and the display screen 9. The laser energy reflectivity of the solid working medium 6 is then obtained and the laser absorption rate of the solid working medium 6 is calculated.

[0039] Carry out the application and performance test of single pulse laser propulsion of solid working fluid. Figure 3 As shown, the laser propulsion application and performance test of solid working fluid are carried out on the torsion pendulum device. The system includes a measuring arm 11, a pivot 12, a solid working fluid 6, a displacement sensor 13, and a laser 1. The laser 1 light source used is Nd:YAG, with a wavelength of 1064nm, a laser pulse width of 10ns, and a laser frequency of 10Hz. When the single-pulse laser energy is focused on the solid working fluid 6 on one side of the torsion pendulum, the working fluid melts, vaporizes, and ionizes to form a high-speed back-spraying laser plasma plume, which causes the measuring arm 11 to deflect at a certain angle in the horizontal direction. The displacement sensor 13 records the position of the measuring arm 11 and calculates the impulse size. The single-pulse laser ablation pit morphology of the solid working fluid is then recorded and the ablation quality is calculated using the formula I sp = I / Δ m g, calculate the specific impulse.

[0040] Where: I sp is the specific impulse; I is the impulse; Δ m is the ablated mass; g is the acceleration due to gravity.

[0041] In the above applications and tests, the scanning electron microscope images, single pulse laser ablation pit morphology and profile analysis used to measure the crystal grain size of metal organic framework materials are shown in the following figure. Figure 1 and Figure 4 、 Figure 5 The relevant test results are shown in Table 1 below.

[0042] Table 1 This scheme introduces a hydrotalcite-carbon quantum dot composite nano-additive during the preparation of metal-organic framework materials. On the one hand, it achieves particle size adjustment and improves laser absorption rate; on the other hand, it enhances decomposition and ionization efficiency. The single-pulse laser ablation depth and ablation mass are small, and the specific impulse generated is high, with the highest specific impulse reaching 1094s, which significantly improves the laser propulsion performance.

Claims

1. A metal-organic framework material with high laser absorptivity, characterized by: The metal organic framework material is a crystalline porous material formed by the interaction of hydrotalcite-carbon quantum dot composite nano-additives, metal ions and organic ligands; The ratio range of the three is: the amount of hydrotalcite added is 0.2%-1.2% of the total mass of organic ligands and metal ions, the amount of carbon quantum dots added is 30%-60% of the amount of hydrotalcite added, and the molar ratio of organic ligands and metal ions added is 35-60:

1.

2. The metal-organic framework material with high laser absorptivity according to claim 1, characterized in that: The metal ion is a metal salt; the organic ligand is a heterocyclic aromatic organic compound.

3. The metal-organic framework material with high laser absorptivity according to claim 1, characterized in that: The metal salt includes one or more of metal nitrates, hydrated nitrates, hydrated chlorides, sulfates, and acetates; and the metal is selected from one of cobalt and zinc.

4. The metal-organic framework material with high laser absorptivity according to claim 1, characterized in that: The organic ligand is one or more of 2-methylimidazole, benzimidazole, nitroimidazole and imidazole-2-carboxaldehyde.

5. The metal-organic framework material with high laser absorptivity according to claim 1, characterized in that: The hydrotalcite-like substance is at least one of a cobalt-aluminum hydrotalcite-like substance and a zinc-aluminum hydrotalcite-like substance.

6. A metal-organic framework material with high laser absorptivity according to claims 1 and 5, characterized in that: The synthesis method of the cobalt-aluminum hydrotalcite is: ① Prepare 600 mL of solution A: an aqueous solution containing 58.2 g of Co(NO3)2·6H2O and 37.5 g of Al(NO3)3·9H2O, and 600 mL of solution B: an aqueous solution containing 48 g of sodium hydroxide and 10.6 g of sodium carbonate; ② Slowly add the two into a four-necked flask, stirring continuously and maintaining argon protection. The pH value of the solution is maintained at 8.5 during the entire synthesis process; ③ After stirring the mixture at 30°C for 1 hour, transfer it to a hydrothermal reactor and maintain it at 90°C for 12 hours. Then, wash it repeatedly with deionized water until the pH value is neutral. ④ Place the sample in an oven at 100℃ and dry for 12 hours until it reaches constant weight. crush; The synthesis method of the zinc-aluminum hydrotalcite is: ① Prepare 600 mL of solution A: an aqueous solution containing 59.5 g of Zn(NO3)2·6H2O and 37.5 g of Al(NO3)3·9H2O, and 600 mL of solution B: an aqueous solution containing 48 g of sodium hydroxide and 10.6 g of sodium carbonate; ② Slowly add the two into a four-necked flask, stirring continuously and maintaining argon protection. The pH value of the solution is maintained at 8.5 during the entire synthesis process; ③ After stirring the mixture at 30°C for 1 hour, transfer it to a hydrothermal reactor and maintain it at 90°C for 12 hours. Then, wash it repeatedly with deionized water until the pH value is neutral. ④ Place the sample in an oven at 100℃ and dry for 12 hours until it reaches constant weight, then grind it into powder; The synthesis method of the carbon quantum dots: ① Weigh 0.1g dopamine hydrochloride and 0.1g o-phenylenediamine and dissolve them in 15mL ethanol. Then transfer them to a hydrothermal reactor and react at 160℃~180℃ for 12 hours. ② After cooling to room temperature, centrifugation and washing with ethanol, further purification was performed using a dialysis membrane for 2 days, and carbon quantum dots were obtained after freeze-drying.

7. A method for preparing a metal-organic framework material with high laser absorptivity comprises the following steps: ① Weighing a hydrotalcite-like substance, adding deionized water, ultrasonically treating it, then adding carbon quantum dots and continuing ultrasonication to adsorb the carbon quantum dots on the surface of the hydrotalcite-like substance to obtain a hydrotalcite-carbon quantum dot composite nano-additive mixture; ② Dissolve the organic ligand in deionized water, then add the hydrotalcite-carbon quantum dot composite nano-additive mixture from step 1, and ultrasonically treat the mixture while controlling the temperature at 15-40°C; ③ Dissolve the metal salt in ionized water and add it to the above mixture in three gradient steps. Let it stand after each addition, with an interval of 30 minutes; ④ Add sodium borohydride aqueous solution to the above mixture, the mass of sodium borohydride added is 0.1%-1% of the mass of the metal salt added, and let it stand at room temperature in the dark for 24 hours without stirring; ⑤ After the reaction is completed, wash with deionized water containing 0.5% EDTA and methanol three times each; ⑥ Place the product in a vacuum drying oven and dry it at a gradient temperature: first heat it at 50℃ for 2h, then heat it at 80℃ for 20h, and finally heat it at 120℃ for 2h.

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