A stress-induced carbon-based heterostructure photothermal synergistic composite phase change material and a preparation method thereof

Abstract

The present application relates to a kind of stress-induced carbon-based heterostructure photothermal synergistic composite phase change material and its preparation method.The present application constructs the carbon-based hetero-interface structure carrier formed by hierarchical porous carbon matrix, first nanoparticle and second nanoparticle coupling by growing another metal organic framework on a kind of metal organic framework and high-temperature carbonization;The stress generated by two kinds of nanoparticles due to lattice mismatch at hetero-interface is used to induce defects at the interface of hierarchical porous carbon matrix, enhance the light absorption characteristics;The existence of stress induces carbon skeleton of hierarchical porous carbon matrix to form carbon defects, promotes non-radiative relaxation process, further strengthens photothermal conversion.The problems of traditional composite phase change material, such as narrow light absorption range, single photothermal conversion mechanism and insufficient controllability of thermal management, are solved, and it has application potential in the fields of solar thermal storage, industrial waste heat recovery and intelligent temperature control system.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials and composite phase change materials, specifically relating to a stress-induced carbon-based heterostructure photothermal synergistic composite phase change material and its preparation method. Background Technology

[0002] Solar energy, as an abundant, clean, and renewable resource, has enormous potential in alleviating the energy crisis and environmental problems. However, its inherent intermittency and instability limit its widespread application. Phase change materials (PCMs) can absorb or release a large amount of latent heat during phase change, possessing numerous advantages such as high latent heat, low supercooling, no phase separation, non-toxicity, and low cost, effectively addressing the intermittency and instability issues of solar energy. However, traditional PCMs suffer from weak solar spectrum absorption and low photothermal conversion efficiency, severely limiting their practical application in direct-drive thermal energy storage technology.

[0003] By employing a porous carrier confinement encapsulation strategy and selecting carrier materials with light absorption capabilities, composite materials can be endowed with high photothermal conversion functionality. Among them, nitrogen-doped carbon derived from metal-organic frameworks has become an ideal carrier for encapsulating phase change materials due to its high specific surface area, tunable pore structure, excellent chemical stability, and good thermal conductivity. Currently, metal / nitrogen-doped carbon materials derived from single metal-organic framework precursors have been extensively studied, and their photothermal performance mainly depends on the local surface plasmon resonance effect of metal nanoparticles and the broadband light absorption of the carbon matrix. However, the light absorption range and energy conversion mechanism of single metal species often have limitations. Integrating two active components with different photoelectric properties (such as metals and metal oxides) at the nanoscale to construct heterostructures, the two components will generate stress due to lattice mismatch when forming a heterostructure interface. This stress can not only modulate the electronic structure of the heterostructure but also induce the generation of local defect states and oxygen vacancies, providing additional driving force for the separation and directional migration of photogenerated carriers. Meanwhile, the coupling effect between the stress field and the built-in electric field of the heterojunction is expected to further optimize the band structure of the material, broaden the light absorption range and enhance the non-radiative relaxation process, thereby achieving a highly efficient photothermal synergistic enhancement effect.

[0004] However, current research on heterostructure composite materials largely focuses on their synthesis methods and basic photocatalytic performance. In-depth and systematic research is lacking on how interfacial stress systematically affects photothermal conversion behavior, particularly how stress-induced defect states synergize with the localized surface plasmon resonance effect of metal nanoparticles to jointly enhance full-spectrum light absorption and thermal energy conversion. Therefore, in-depth research on stress-induced photothermal conversion behavior is of great significance for revealing the structure-activity relationship between heterojunction interfacial structure and photothermal performance, optimizing carrier separation and transport pathways, improving the full-spectrum absorption capacity and photothermal conversion efficiency of composite phase change materials, and ultimately promoting the development of efficient solar energy storage and utilization technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a stress-induced carbon-based heterostructure photothermal synergistic composite phase change material and its preparation method. The core of this invention lies in designing and constructing a carbon-based heterostructure carrier formed by the coupling of a hierarchical porous carbon matrix, first nanoparticles, and second nanoparticles. Stress, caused by lattice mismatch between the two nanoparticles, is introduced at the heterostructure interface. This stress induces carbon defects within the hierarchical porous carbon matrix, promoting non-radiative relaxation processes. Simultaneously, this carbon-based heterostructure carrier achieves fully confined encapsulation of the phase change material, ultimately yielding a composite phase change material with both high energy storage density and high photothermal conversion capability. The preparation method of this invention is simple and efficient, facilitating large-scale industrial production and opening up an efficient path for solar energy storage and utilization, possessing practical application value.

[0006] This invention provides a method for preparing stress-induced carbon-based heterostructure photothermal synergistic composite phase change materials, comprising the following steps: (1) A metal-organic framework MOF(B) is grown in situ on another metal-organic framework MOF(A) to obtain a MOF(A)@MOF(B) precursor containing two metal-organic frameworks; (2) The MOF(A)@MOF(B) precursor containing two metal-organic frameworks prepared in step (1) is carbonized at high temperature in an inert atmosphere. MOF(A) is carbonized to form a hierarchical porous carbon matrix and the first nanoparticle is coupled with the second nanoparticle formed by the carbonization of MOF(B) to obtain a carbon-based heterostructure carrier. (3) The phase change material is loaded into the carbon-based heterostructure carrier to obtain a composite phase change material.

[0007] Precursors containing two metal-organic frameworks, MOF(A) and MOF(B), were synthesized using the following method: (a) Disperse a cobalt-containing metal salt in methanol to form solution A. Disperse nitrogen-containing heterocyclic organic ligands separately in methanol to form solution B. Mix solution A and solution B in a ratio of 1:4 or 1:8 and stir until homogeneous to form a homogeneous mixed solution. (b) The homogeneous mixed solution in step (a) is centrifuged, washed 3 to 5 times with methanol solvent, and then dried under vacuum at 60 to 80 °C for 12 to 24 h to obtain MOF(A) powder. (c) Disperse the MOF(A) powder obtained in step (b) in DMF solvent, disperse the metal salt in this solution and stir for 8-12 h, then disperse the amino-containing organic ligand in the mixed solution, add triethylamine to adjust the pH of the system to 7-8, stir for 2-4 h to obtain a colloidal suspension. (d) The colloidal suspension was subjected to centrifugation, washing with DMF solvent 3-5 times and methanol solvent 3-5 times in sequence, and then dried under vacuum at 60-80℃ for 12-24h to obtain MOF(A)@MOF(B) powder.

[0008] The photothermal synergistic carbon-based heterostructure support was prepared using the following method: MOF(A)@MOF(B) support containing two metal-organic frameworks was placed under an inert atmosphere and heated to 700-1000℃ at a heating rate of 1-5℃ / min. The temperature was then maintained at this temperature for 3-5 hours to obtain a photothermal synergistic carbon-based heterostructure support.

[0009] The following method was used to synthesize carbon-based heterostructure photothermal synergistic composite phase change materials: The photothermal synergistic carbon-based heterostructure carrier and the phase change material prepared above were ground thoroughly in a mortar at a ratio of 1:5 to 5:1 to ensure uniform mixing. Then, the mixture was dried in an oven at 80°C for 10 to 15 minutes. The grinding and drying operations were repeated 5 to 10 times to obtain the photothermal synergistic carbon-based heterostructure composite phase change carrier.

[0010] The cobalt-containing metal salts applicable to this invention include, but are not limited to, one or more of cobalt nitrate, cobalt chloride, cobalt sulfate, cobalt carbonate, and cobalt oxalate.

[0011] Nitrogen-containing heterocyclic organic ligands suitable for this invention include one or more of the following: imidazole, 2-methylimidazolium, benzimidazole, 1,2,4-triazole, purines, and their derivatives; amino-containing organic ligands suitable for this invention include one or more of the following: 2-aminoterephthalic acid, 3-amino-1,2,4-triazole, and 2-aminobiphenyl-4,4'-dicarboxylic acid. Metal salts with catalytic properties suitable for this invention include one or more of the following: manganese nitrate, manganese chloride, copper nitrate, copper chloride, cerium nitrate, aluminum nitrate, zinc nitrate, zinc chloride, nickel nitrate, nickel chloride, nickel sulfate, cerium nitrate, and cerium sulfate.

[0012] The beneficial effects of this invention are: The method of this invention successfully constructed a carbon-based heterostructure carrier formed by the coupling of a hierarchical porous carbon matrix, first nanoparticles, and second nanoparticles. This enabled the confined encapsulation of phase change materials within the carbon-based heterostructure carrier, resulting in a composite phase change material with both high energy storage density and high photothermal conversion capability. The stress induced by lattice mismatch between the two nanoparticles at the heterostructure interface induces carbon defects within the hierarchical porous carbon matrix, promoting non-radiative relaxation and improving photothermal conversion efficiency. Simultaneously, the synergistic effect of stress-induced interface defects and the localized surface plasmon resonance effect of the first nanoparticles at the heterostructure interface achieves efficient utilization of the entire solar spectrum. This invention utilizes interface stress to regulate the atomic-scale bonding structure, breaking through the bottleneck of improving photothermal conversion efficiency at the microscopic mechanism level. By utilizing the micro-nano porous structure of a carbon-based support to confine and encapsulate phase change materials, the liquid phase leakage problem of the molten core material is effectively solved through capillary forces and surface tension, significantly improving the material's thermal stability and cycle life. Furthermore, the pore confinement effect regulates the crystallization behavior and phase change kinetics of the core material, enabling precise control of the phase change temperature and latent heat, and endowing the material with adaptability for controllable release and storage of thermal energy over a wide temperature range. The preparation method of this invention is simple, efficient, and suitable for large-scale production. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 shows the TEM image of the carrier material obtained in Embodiment 1 of the present invention.

[0015] Figure 2 shows the XRD pattern of the carrier material obtained in Embodiment 1 of the present invention.

[0016] Figure 3 shows the XRD pattern of the composite phase change material obtained in Embodiment 1 of the present invention.

[0017] Figure 4 shows the DSC spectrum of the composite phase change material obtained in Embodiment 1 of the present invention.

[0018] Figure 5 shows the photothermal temperature change curve of the composite phase change material obtained in Embodiment 1 of the present invention.

[0019] Figure 6 shows the photothermal temperature change curve of the composite phase change material obtained in Embodiment 2 of the present invention.

[0020] Figure 7 shows the photothermal temperature change curve of the composite phase change material obtained in Embodiment 3 of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. Implementation Case 1

[0023] Preparation of carbon-based heterostructure support materials: Cobalt nitrate was dissolved in methanol to prepare solution A. 2-Methylimidazole was then dissolved in methanol to prepare solution B, with a cobalt nitrate to dimethylimidazole ratio of 1:4. The resulting mixture was stirred at room temperature for 24 h, centrifuged, washed three times with methanol, and dried in an 80°C vacuum oven for 24 h to obtain the ZIF-67 precursor. ZIF-67 was dissolved in DMF solution, and then manganese chloride was added to the ZIF-67 solution, and the mixture was stirred for 12 h. Then, 2-aminoterephthalic acid was added to the above solution, and the mixture was stirred until the reactants dissolved. Triethylamine was then slowly added dropwise, and the mixture was stirred for 120 min. After centrifugation, the mixture was washed three times with DMF and methanol, and then dried in an 80°C vacuum oven for 24 h. The temperature was programmed to rise to 800°C at a rate of 2°C / min, and carbonized at this temperature for 5 h to finally obtain the carbon-based heterostructure support material.

[0024] Preparation of composite phase change materials: The stress-induced carbon-based heterostructure support material prepared above was mixed with polyethylene glycol at a ratio of 4:6. The mixed material was dried in an 80°C vacuum drying oven for 4 hours, and then repeatedly ground in a mortar. The ground material was then placed in an 80°C vacuum drying oven, and the grinding and drying process was repeated multiple times to finally obtain the carbon-based heterostructure composite phase change support.

[0025] Test results show that Figure 1 The TEM images show the formation of a Co and MnO heterojunction. Figure 2 The XRD results show that the diffraction peaks at 44.22°, 51.52°, and 75.86° are attributed to the (111), (200), and (220) crystal planes of the Co nanoparticles. Obvious crystal diffraction peaks are observed at 34.92°, 40.54°, 58.69°, 70.15°, and 73.76°, corresponding to the (111), (200), (220), (311), and (222) crystal planes of MnO, respectively. From the XRD results of the composite phase change material in Figure 3, the characteristic peaks of polyethylene glycol are clearly observed, confirming that a composite phase change material with excellent crystallinity was successfully obtained using this experimental scheme. The DSC test results of the composite phase change material prepared in this implementation case are as follows: Figure 4 As shown, the results indicate that the melting temperature of the composite phase change material is 62.8℃, the enthalpy of melting is 92.5 J / g, the solidification temperature is 45.4℃, and the enthalpy of solidification is 90.2 J / g. Figure 5 As shown, under the simulated light intensity of one standard sun, the surface temperature of the phase change material rises to 89.8℃ within 600s, and its photothermal energy storage efficiency is as high as 96.0%, confirming that the prepared composite phase change material has excellent photothermal conversion performance. Implementation Case 2

[0026] Preparation of carbon-based heterostructure support materials: Cobalt nitrate was dissolved in methanol to prepare solution A. 2-Methylimidazole was then dissolved in methanol to prepare solution B, with a cobalt nitrate to dimethylimidazole ratio of 1:4. The resulting mixture was stirred at room temperature for 24 h, centrifuged, washed three times with methanol, and dried in an 80°C vacuum oven for 24 h to obtain the ZIF-67 precursor. ZIF-67 was dissolved in DMF solution, and then zinc nitrate was added to the ZIF-67 solution, and the mixture was stirred for 12 h. Then, 2-aminoterephthalic acid was added to the above solution, and the mixture was stirred until the reactants dissolved. Triethylamine was then slowly added dropwise, and the mixture was stirred for 120 min. After centrifugation, the mixture was washed three times with DMF and methanol, and then dried in an 80°C vacuum oven for 24 h. The temperature was programmed to rise to 800°C at a rate of 2°C / min, and carbonized at this temperature for 5 h to finally obtain the carbon-based heterostructure support material.

[0027] Preparation of composite phase change materials: The stress-induced carbon-based heterostructure support material prepared above was mixed with polyethylene glycol at a ratio of 4:6. The mixed material was dried in an 80°C vacuum drying oven for 4 hours, and then repeatedly ground in a mortar. The ground material was then placed in an 80°C vacuum drying oven, and the grinding and drying process was repeated multiple times to finally obtain the carbon-based heterostructure composite phase change support.

[0028] Photothermal test results show that, under the simulated light intensity of one standard sun, the temperature of the lower surface of the composite phase change material rises to 71.3℃ within 600s, and its photothermal energy storage efficiency is as high as 94.8%, confirming that the prepared composite phase change material has excellent photothermal conversion performance. Implementation Case 3

[0029] Preparation of carbon-based heterostructure support materials: Cobalt nitrate was dissolved in methanol to prepare solution A. 2-Methylimidazole was then dissolved in methanol to prepare solution B, with a cobalt nitrate to dimethylimidazole ratio of 1:4. The resulting mixture was stirred at room temperature for 24 h, centrifuged, washed three times with methanol, and dried in an 80°C vacuum oven for 24 h to obtain the ZIF-67 precursor. ZIF-67 was dissolved in DMF solution, and then copper sulfate was added to the ZIF-67 solution, with stirring for 12 h. 2-Aminoterephthalic acid was then added to the above solution, and the mixture was stirred until the reactants dissolved. Triethylamine was then slowly added dropwise, and the mixture was stirred for 120 min. After centrifugation, the mixture was washed three times with DMF and methanol, and then dried in an 80°C vacuum oven for 24 h. The temperature was programmed to rise to 800°C at a rate of 2°C / min, and carbonized at this temperature for 5 h to finally obtain the carbon-based heterostructure support material.

[0030] Preparation of composite phase change materials: The stress-induced carbon-based heterostructure support material prepared above was mixed with polyethylene glycol at a ratio of 4:6. The mixed material was dried in an 80°C vacuum drying oven for 4 hours, and then repeatedly ground in a mortar. The ground material was then placed in an 80°C vacuum drying oven, and the grinding and drying process was repeated multiple times to finally obtain the carbon-based heterostructure composite phase change support.

[0031] Photothermal test results show that, under the simulated light intensity of one standard sun, the temperature of the lower surface of the composite phase change material rises to 71.5℃ within 300s, and its photothermal energy storage efficiency is as high as 95.8%, confirming that the prepared composite phase change material has excellent photothermal conversion performance.

Claims

1. A stress-induced carbon-based heterostructure photothermal synergistic composite phase change material, characterized in that, It includes a hierarchical porous carbon matrix, first nanoparticles and second nanoparticles loaded on the hierarchical porous carbon matrix; and a carbon-based heterostructure carrier formed by the coupling of the hierarchical porous carbon matrix, the first nanoparticles and the second nanoparticles.

2. The stress-induced carbon-based heterostructure photothermal synergistic composite phase change material according to claim 1, characterized in that, The carbon-based heterostructure carrier promotes nonradiative relaxation processes through carbon defects formed within a hierarchical porous carbon matrix. The localized surface plasmon resonance effect of the first nanoparticle enhances the electromagnetic field in the visible-near-infrared region, and the second nanoparticle enhances the photoresponse in the ultraviolet-visible region through defect states and interband transitions.

3. The stress-induced carbon-based heterostructure photothermal synergistic composite phase change material according to claim 1, characterized in that, The hierarchical porous carbon matrix has a heterogeneous interface, where stress exists due to the lattice mismatch between the first nanoparticle and the second nanoparticle.

4. The stress-induced carbon-based heterostructure photothermal synergistic composite phase change material according to claim 3, characterized in that, The carbon-based heterostructure carrier forms interface defect states due to stress induction. There are abundant oxygen vacancies at the interface, and the generation of stress induces the formation of carbon defects in the hierarchical porous carbon matrix.

5. A method for preparing stress-induced carbon-based heterostructure photothermal synergistic composite phase change materials, characterized in that, Includes the following steps: (1) A metal-organic framework MOF(B) is grown in situ on another metal-organic framework MOF(A) to obtain a MOF(A)@MOF(B) precursor containing two metal-organic frameworks; (2) The MOF(A)@MOF(B) precursor containing two metal-organic frameworks prepared in step (1) is carbonized at high temperature in an inert atmosphere. MOF(A) is carbonized to form a hierarchical porous carbon matrix and the first nanoparticle is coupled with the second nanoparticle formed by the carbonization of MOF(B) to obtain a carbon-based heterostructure carrier. (3) The phase change material is loaded into the carbon-based heterostructure carrier to obtain a composite phase change material.

6. The method for preparing a stress-induced carbon-based heterostructure photothermal synergistic composite phase change material according to claim 5, characterized in that, The preparation method of the MOF(A)@MOF(B) precursor containing two metal-organic frameworks obtained in step (1) is as follows: (a) Disperse a cobalt-containing metal salt in methanol to form solution A. Disperse nitrogen-containing heterocyclic organic ligands separately in methanol to form solution B. Mix solution A and solution B in a ratio of 1:4 or 1:8 and stir until homogeneous to form a homogeneous mixed solution. (b) The homogeneous mixed solution in step (a) is centrifuged, washed 3 to 5 times with methanol solvent, and then dried under vacuum at 60 to 80 °C for 12 to 24 h to obtain MOF(A) powder. (c) Disperse the MOF(A) powder obtained in step (b) in DMF solvent, disperse the metal salt in this solution and stir for 8-12 h, then disperse the amino-containing organic ligand in the mixed solution, add triethylamine to adjust the pH of the system to 7-8, stir for 2-4 h to obtain a colloidal suspension. (d) The colloidal suspension was subjected to centrifugation, washing with DMF solvent 3-5 times and methanol solvent 3-5 times in sequence, and then dried under vacuum at 60-80℃ for 12-24h to obtain MOF(A)@MOF(B) powder.

7. The method for preparing a stress-induced carbon-based heterostructure photothermal synergistic composite phase change material according to claim 5, characterized in that, The preparation method of the carbon-based heterostructure carrier obtained in step (2) is as follows: the MOF(A)@MOF(B) carrier containing two metal-organic frameworks is placed under an inert atmosphere and heated to 700~1000℃ at a heating rate of 1~5℃ / min, and carbonized at this temperature for 3~5h to finally obtain the carbon-based heterostructure carrier.

8. A stress-induced carbon-based heterostructure photothermal synergistic composite phase change material according to claim 6, characterized in that, The cobalt-containing metal salt includes one or more of cobalt nitrate, cobalt chloride, cobalt sulfate, cobalt carbonate, and cobalt oxalate; the nitrogen-containing heterocyclic organic ligand includes one or more of imidazole, 2-methylimidazolium, benzimidazole, 1,2,4-triazole, purine, and their derivatives; the amino-containing organic ligand includes one or more of 2-aminoterephthalic acid, 3-amino-1,2,4-triazole, and 2-aminobiphenyl-4,4'-dicarboxylic acid; the metal salt includes one or more of manganese nitrate, manganese chloride, copper nitrate, copper chloride, cerium nitrate, aluminum nitrate, zinc nitrate, zinc chloride, nickel nitrate, nickel chloride, nickel sulfate, cerium nitrate, and cerium sulfate.

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