Photo-thermal composite phase change material with built-in electric field for driving heterogeneous interface electron transfer and preparation method of photo-thermal composite phase change material

Abstract

The invention relates to a photo-thermal composite phase-change material with a built-in electric field for driving heterogeneous interface electron transfer and a preparation method of the photo-thermal composite phase-change material. The preparation method comprises the following steps: adsorbing multi-element metal through a metal organic framework precursor, and performing high-temperature carbonization to construct a graphitized carbon encapsulated metal nanoparticle coupled metal oxide ternary heterogeneous interface structure carrier; a built-in electric field is induced to be generated at a heterogeneous interface by utilizing Fermi energy level difference between the metal nanoparticles and the metal oxide, and electrons are driven to be transferred between the metal nanoparticles and the metal oxide; rich oxygen vacancies in the metal oxide effectively capture electrons, and efficient and controllable photon-generated carrier separation and utilization are achieved; and a pi-pi conjugate network of graphitized carbon forms a continuous electron transmission channel, so that rapid conduction of heat is further guaranteed. The problems that a traditional composite phase change material is high in carrier recombination rate, single in photothermal conversion mechanism and insufficient in thermal management controllability are solved, and the composite phase change material has application potential in the fields of solar heat storage, industrial waste heat recovery, intelligent temperature control systems and the like.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials and composite phase change materials technology, specifically relating to a photothermal composite phase change material with built-in electric field-driven electron transfer at heterogeneous interfaces and its preparation method. Background Technology

[0002] Phase change materials (PCMs) are ideal media for the storage and controlled release of solar thermal energy due to their high energy density and near-isothermal phase change process. However, traditional organic PCMs have extremely weak absorption capacity for sunlight and low thermal conductivity, resulting in low photothermal conversion efficiency and slow thermal response. This makes them difficult to play an effective role in solar thermal storage systems that directly utilize sunlight, severely restricting the practical application of solar direct-drive thermal energy storage technology.

[0003] To improve the photothermal performance of phase change materials (PCMs), a common strategy is to introduce highly photothermally active carriers to construct composite materials. Among these, carbon-based composites derived from metal-organic frameworks (MOFs) exhibit unique advantages. These materials not only fully inherit the highly ordered pore structure and tunable pore size distribution of MOF precursors, providing an ideal space for high-capacity, high-stability confined encapsulation of PCMs, but also, through a high-temperature carbonization process, can simultaneously form graphitized carbon frameworks with broadband light absorption capabilities and metal nanoparticles with localized surface plasmon resonance effects. This carbon-coupled metal composite system, through the synergistic effect of π-π conjugation and the plasmon resonance effect of metal nanoparticles, can effectively enhance the photothermal conversion capability of composite PCMs. However, existing technologies are still limited to photoexcited plasmons or hot carriers, which are mainly converted into lattice thermal energy at a single interface through rapid nonradiative relaxation. This process lacks an effective directional energy guidance and extraction mechanism, resulting in a large amount of energy being dissipated as disordered heat. Material systems based on carbon-based metal nanoparticles coupled with metal oxides in a multi-element heterogeneous design can effectively regulate charge distribution and reduce transfer barriers through interfacial interactions, thereby significantly promoting the separation and transport of photogenerated carriers. However, the advantages of this system have not yet been fully explored and utilized in applications for photothermal conversion and phase change energy storage. Most current research remains focused on catalytic performance optimization, failing to systematically address key issues in photothermal-phase change composite systems, such as the photon-thermon synergistic conversion mechanism, heterogeneous interface thermal transport regulation, and multi-scale thermal coupling with phase change materials. This has resulted in the structure not yet realizing its expected potential in the design of efficient and stable photothermal energy storage materials.

[0004] In summary, precisely designing and constructing multi-component heterostructures with strong interfacial coupling and built-in electric fields at the molecular scale, thereby establishing efficient photogenerated carrier separation and transport channels, is key to overcoming the bottleneck of photothermal performance in existing composite phase change materials. The ternary heterostructure of "graphitized carbon-encapsulated metal nanoparticles coupled with metal oxides" constructed in this invention is not only an efficient photothermal conversion and charge management unit, but also possesses excellent material versatility and morphological scalability. This structural unit can serve as a functional building block, flexibly adapting to different application forms and scenarios by adjusting the composite method of the carrier and matrix: it can act as a functional filler, uniformly dispersed and composited into a polymer matrix to prepare flexible self-supporting films or coatings, suitable for thermal management of wearable devices and flexible electronic devices; it can also be molded into arbitrarily shaped composite phase change blocks or components through molding, 3D printing, and other processes to meet the specific shape and structural strength requirements of building walls, industrial thermal storage tanks, etc.; and it can also serve as a highly efficient photothermal medium, directly applied to the fluid of solar collectors or thermal storage capsules. This design concept of decoupling "functional unit-application form" means that the core material technology of this invention is no longer limited to specific product forms, but has the potential for universal application to diversified and customized solar thermal energy storage use cases, providing a solid material foundation for the development of high-efficiency thermal energy storage and intelligent management systems driven by solar energy. Summary of the Invention

[0005] The purpose of this invention is to provide a photothermal composite phase change material with an internally driven electric field for electron transfer at a heterogeneous interface. The core of this invention lies in designing and constructing a ternary heterostructure carrier encapsulating metal nanoparticles coupled with metal oxides using graphitized carbon. An internal electric field induced by the Fermi level difference is introduced at the interface between the metal nanoparticles and the metal oxides, enabling efficient transfer of photogenerated electrons between the metal nanoparticles and the metal oxides while suppressing recombination of photogenerated carriers. Simultaneously, the multi-level pores of this ternary heterostructure carrier achieve fully confined encapsulation of the phase change material, ultimately obtaining a composite phase change material with both high-efficiency photothermal conversion and high-density energy storage performance. This method offers controllable and reproducible processes, providing a new approach for the design of high-performance solar photothermal conversion and storage materials.

[0006] This invention provides a method for preparing a photothermal composite phase change material with built-in electric field-driven electron transfer at a heterogeneous interface, the method comprising the following steps: (1) In a metal-organic framework material MOF(A), a precursor containing two metal components, MOF(A,B,C), is obtained by adsorbing exogenous metal ions B and C. (2) The MOF (A,B,C) precursor containing three metal components prepared in step (1) is carbonized at high temperature in an inert atmosphere to obtain a ternary heterostructure support. (3) Add the ternary heterostructure carrier prepared in step (2) and the phase change material to an ethanol solution at a mass ratio of 4:1 to 1:4, sonicate for 20 to 60 minutes to ensure complete contact and thorough mixing, and dry in a vacuum oven at 30 to 100°C for 12 to 24 hours to obtain the composite phase change material.

[0007] MOF (A, B, C) precursors containing three metal components were synthesized using the following method: (a) A zinc-containing metal salt and an amino-containing organic ligand are dispersed in DMF solvent at a molar ratio of 1:2 to 2:1 to form a homogeneous mixed solution; (b) Triethylamine was added to the homogeneous mixed solution of step (a) to adjust the pH of the system to 7-8, and a colloidal suspension was obtained after stirring. (c) The colloidal suspension is subjected to centrifugation, washing with DMF solvent 3 to 5 times and methanol solvent 3 to 5 times in sequence, and then dried under vacuum at 60 to 80°C for 12 to 24 hours to obtain MOF(A) powder. (d) The MOF(A) powder and the substance containing the catalytic metal salt and the third metal salt are dispersed together in DMF solvent to obtain a mixed solution, and the molar ratio of the catalytic metal salt and the third metal salt in the mixed solution is controlled to be 1:3~3:1; (e) The mixed solution from step (d) is ultrasonically dispersed for 20-60 min, then reacted under stirring for 2-5 h, the reaction product is separated by centrifugation, and dried under vacuum at 60-80 °C for 12-24 h to finally obtain the MOF(A,B,C) precursor containing two metal components.

[0008] The ternary heterostructure carrier was synthesized using the following method: MOF (A,B,C) precursors containing three metal components were placed under an inert atmosphere and heated to 900-1200℃ at a heating rate of 1-5℃ / min. The precursors were then isothermally carbonized at this temperature for 2-6 hours to obtain a ternary heterostructure support.

[0009] The zinc-containing metal salts applicable to this invention include, but are not limited to, one or more of the following: zinc nitrate, zinc sulfate, zinc acetate, zinc chloride, and their hydrates; the amino-containing organic ligands include, but are not limited to, one or more of the following: 2-aminoterephthalic acid, 3-amino-1,2,4-triazole, and 2-aminobiphenyl-4,4'-dicarboxylic acid.

[0010] The catalytically oriented metal salts applicable to this invention include one or more of the following: nickel nitrate, nickel sulfate, nickel acetate, nickel chloride, cobalt nitrate, cobalt chloride, cobalt sulfate, cobalt acetate, ferric nitrate, ferric chloride, ferric sulfate, ferric acetate, etc., and their hydrates; the third metal salt can be oxidized to a semiconductor oxide at high temperature, including lanthanide metal salts such as cerium nitrate, cerium chloride, cerium acetate, etc., and their hydrates, as well as one or more of the following: titanium tetrachloride, titanium oxysulfate, titanium trichloride, tin tetrachloride, tin sulfate, tin acetate, zirconium oxynitrate, zirconium oxychloride, zirconium acetate, aluminum nitrate nonahydrate, polyaluminum chloride, hafnium tetrachloride, yttrium nitrate, yttrium chloride, etc., and their hydrates.

[0011] The beneficial effects of this invention are: The method of this invention successfully constructed a ternary heterostructure carrier with built-in electric field-driven interfacial electron transfer, achieving efficient confined encapsulation of phase change materials in a multi-element synergistic carrier, thus obtaining a composite phase change material with significantly improved photothermal conversion and energy storage performance. By introducing a built-in electric field induced by the Fermi level difference at the ternary heterostructure interface, the transfer and capture of photogenerated electrons between metal nanoparticles and metal oxides were realized, effectively suppressing carrier recombination and improving photothermal conversion efficiency. Simultaneously, the continuous electron transport network formed by the graphitized carbon framework, the localized surface plasmon resonance effect of the metal nanoparticles, and the broad-spectrum light absorption of the metal oxides synergistically enabled efficient utilization of the entire solar spectrum. Furthermore, the multi-level porous structure inherited from the metal-organic framework precursor provides a stable encapsulation space and sufficient contact interface for the phase change material, ensuring high energy storage density and good cycle stability. This preparation method uses a structurally tunable metal-organic framework as a precursor. The process is simple and highly controllable, providing an effective way for the controllable preparation and large-scale application of high-performance solar thermal energy storage materials. It has broad application prospects in the fields of solar thermal storage and intelligent thermal management. Attached Figure Description

[0012] 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.

[0013] Figure 1 This is a TEM image of the carrier material obtained in Example 1 of the present invention.

[0014] Figure 2 The image shows the XRD pattern of the carrier material obtained in Example 1 of this invention.

[0015] Figure 3The image shows the XRD pattern of the composite phase change material obtained in Example 1 of this invention.

[0016] Figure 4 The image shows the DSC spectrum of the composite phase change material obtained in Example 1 of this invention.

[0017] Figure 5 The image shows the photothermal temperature change curve of the composite phase change material obtained in Example 1 of this invention.

[0018] Figure 6 The photothermal temperature change curve of the composite phase change material obtained in Example 2 of this invention is shown.

[0019] Figure 7 The photothermal temperature change curve of the composite phase change material obtained in Example 3 of this invention is shown. Detailed Implementation

[0020] 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.

[0021] Example 1 (1) Preparation of carbon-encapsulated Co-coupled CeO2 ternary heterostructure carrier material: Zinc nitrate hexahydrate and 2-aminoterephthalic acid were dispersed in DMF solvent at a molar ratio of 2:1 to form a homogeneous mixed solution. Triethylamine solution was then added to adjust the pH to 7. After stirring, a colloidal suspension was obtained, which was then subjected to centrifugation, washing three times with DMF solvent, and washing three times with methanol solvent. The suspension was then dried under vacuum at 80°C for 24 hours to obtain MOF(Zn) powder. MOF(Zn) powder, cobalt nitrate hexahydrate, and cerium nitrate hexahydrate were co-dispersed in DMF solvent, with the molar ratios of the metal salts controlled. The ratio was 1:1; then the mixed solution was ultrasonically dispersed for 30 min and reacted for 2 h under stirring. After centrifugation and washing, the product was dried under vacuum at 80 °C for 24 h to finally obtain a MOF (Zn, Co, Ce) precursor containing three metal components; the MOF (Zn, Co, Ce) precursor containing three metal components was placed under Ar atmosphere protection and heated to 1000 °C at a heating rate of 2 °C / min, and carbonized at this temperature for 3 h to finally obtain a ternary heterostructure support; (2) Preparation of composite phase change materials The ternary heterostructure carrier prepared above was added to an ethanol solution at a mass ratio of 3:7 with polyethylene glycol 4000. The mixture was ultrasonically treated for 30 minutes to ensure complete contact and thorough mixing. Then, it was dried in a vacuum oven at 80°C for 24 hours to obtain the composite phase change material.

[0022] By employing in-situ confined growth technology and utilizing molecular-level carbon precursor coordination regulation and pyrolysis strategies, a gradient heterostructure nickel-coupled highly graphitized carbon hybrid support was successfully constructed. Figure 1 The TEM images clearly show nickel-coupled highly graphitized plasmon enhancement sites. Figure 2 The XRD results show that the support has diffraction peaks at 44.2°, 51.5°, and 76.1° corresponding to the (111), (200), and (220) crystal planes of cobalt nanoparticles, respectively, and diffraction peaks at 28.5°, 33.0°, 47.5°, 56.4°, and 76.5° corresponding to the (111), (200), (220), (311), and (331) crystal planes of cubic fluorite cerium oxide, respectively. This support can effectively adsorb polyethylene glycol and rapidly achieve photothermal conversion from... Figure 3 The XRD results of the composite phase change material clearly show the characteristic peaks of polyethylene glycol, confirming that the experimental method successfully yielded a composite phase change material with excellent crystallinity. The DSC test results of the composite phase change material prepared in this case are as follows: Figure 4 As shown, the results indicate that the composite phase change material has a melting temperature of 60.8℃, a melting enthalpy of 105.8 J / g, a solidification temperature of 41.0℃, and a solidification enthalpy of 97.6 J / g. Furthermore, after 300 cycles, the phase change temperature and phase change value show no significant changes, demonstrating excellent thermal cycling stability. The photothermal data curves of the composite phase change material are shown below. Figure 5 As shown, under the simulated light intensity of one standard sun, the temperature of the lower surface of the composite phase change material rises to 74.5℃ within 300s, and its photothermal energy storage efficiency is as high as 95.9%, which confirms that the prepared composite phase change material has excellent photothermal conversion performance.

[0023] Example 2 (1) Preparation of carbon-encapsulated Co-coupled Y2O3 ternary heterostructure carrier material: Zinc nitrate hexahydrate and 2-aminoterephthalic acid were dispersed in DMF solvent at a molar ratio of 2:1 to form a homogeneous mixture. Triethylamine solution was then added to adjust the pH to 7. After stirring, a colloidal suspension was obtained, which was subsequently centrifuged, washed three times with DMF solvent, and washed three times with methanol solvent. The suspension was then dried under vacuum at 80°C for 24 hours to obtain MOF(Zn) powder. The MOF(Zn) powder, cobalt nitrate hexahydrate, and yttrium nitrate were then co-dispersed in DMF solvent, with the molar ratios of the metal salts controlled. The ratio was 1:1. The mixed solution was then ultrasonically dispersed for 30 min and reacted for 2 h under stirring. After centrifugation and washing, the product was dried under vacuum at 80 °C for 24 h to finally obtain a MOF (Zn,Co,Y) precursor containing three metal components. The MOF (Zn,Co,Y) precursor containing three metal components was placed under Ar atmosphere protection and heated to 1000 °C at a heating rate of 2 °C / min. It was then carbonized at this temperature for 3 h to finally obtain a ternary heterostructure support. (2) Preparation of composite phase change materials The ternary heterostructure carrier prepared above was added to an ethanol solution at a mass ratio of 3:7 with polyethylene glycol, and ultrasonically treated for 30 min to ensure complete contact and thorough mixing. Then, it was dried in a vacuum oven at 80℃ for 24 h to obtain the composite phase change material.

[0024] 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 72.2℃ within 300s, 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.

[0025] Example 3 (1) Preparation of carbon-encapsulated Co-coupled La2O3 ternary heterostructure carrier material: Zinc nitrate hexahydrate and 2-aminoterephthalic acid were dispersed in DMF solvent at a molar ratio of 2:1 to form a homogeneous mixed solution. Triethylamine solution was then added to adjust the pH to 7. After stirring, a colloidal suspension was obtained, which was then subjected to centrifugation, washing three times with DMF solvent, and washing three times with methanol solvent. The suspension was then dried under vacuum at 80℃ for 24 h to obtain MOF(Zn) powder. MOF(Zn) powder, cobalt nitrate hexahydrate, and lanthanum nitrate were co-dispersed in DMF solvent, with the molar ratio of metal salts controlled. The ratio was 1:1. The mixed solution was then ultrasonically dispersed for 30 min and reacted for 2 h under stirring. After centrifugation and washing, the product was dried under vacuum at 80 °C for 24 h to finally obtain a MOF (Zn, Co, La) precursor containing three metal components. The MOF (Zn, Co, La) precursor containing two metal components was placed under Ar atmosphere protection and heated to 1000 °C at a heating rate of 2 °C / min. It was then carbonized at this temperature for 3 h to finally obtain a ternary heterostructure support. (2) Preparation of composite phase change materials The carbon-encapsulated ternary heterostructure carrier prepared above was added to an ethanol solution at a mass ratio of 3:7 with polyethylene glycol. The mixture was ultrasonically treated for 30 minutes to ensure complete contact and thorough mixing. Then, it was dried in a vacuum oven at 80°C for 24 hours to obtain the composite phase change material.

[0026] 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 73.5℃ within 300s, and its photothermal energy storage efficiency is as high as 95.5%, confirming that the prepared composite phase change material has excellent photothermal conversion performance.

[0027] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0028] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A photothermal composite phase change material with built-in electric field-driven interfacial electron transfer, characterized in that, The invention includes graphitized carbon-encapsulated metal nanoparticles, a metal oxide coupled to the graphitized carbon-encapsulated metal nanoparticles, and a ternary heterostructure carrier formed by the coupling of the graphitized carbon-encapsulated metal nanoparticles and the metal oxide.

2. The photothermal composite phase change material with built-in electric field-driven interface electron transfer according to claim 1, characterized in that, The ternary heterostructure carrier forms a continuous electron transport network through a graphitized carbon framework π-π conjugated system. The graphitized carbon-encapsulated metal nanoparticles generate electromagnetic field enhancement in the visible-near infrared region through localized surface plasmon resonance. The metal oxides supplement the ultraviolet-visible response through interband transitions and defect state absorption.

3. The photothermal composite phase change material with built-in electric field-driven interface electron transfer according to claim 1, characterized in that, The ternary heterostructure carrier has a ternary heterostructure interface, and the ternary heterostructure interface has a built-in electric field that can drive electron transfer.

4. The photothermal composite phase change material with built-in electric field-driven interface electron transfer according to claim 3, characterized in that, There is a Fermi level difference at the ternary heterostructure interface; the built-in electric field is induced by the Fermi level difference and can drive the transfer of electrons between the metal nanoparticles and the metal oxide. The metal oxide has abundant oxygen vacancies and can capture electrons.

5. A method for preparing a photothermal composite phase change material with built-in electric field-driven interfacial electron transfer, characterized in that, Includes the following steps: (1) In a metal-organic framework material MOF(A), a precursor containing two metal components, MOF(A,B,C), is obtained by adsorbing exogenous metal ions B and C. (2) The MOF (A,B,C) precursor containing three metal components prepared in step (1) is carbonized at high temperature in an inert atmosphere to obtain a ternary heterostructure support. (3) Add the ternary heterostructure carrier prepared in step (2) and the phase change material to an ethanol solution at a mass ratio of 4:1 to 1:4, sonicate for 20 to 60 minutes to ensure complete contact and thorough mixing, and dry in a vacuum oven at 30 to 100°C for 12 to 24 hours to obtain the composite phase change material.

6. The method for preparing a photothermal composite phase change material with built-in electric field-driven interfacial electron transfer according to claim 5, characterized in that, The preparation method of the MOF (A,B,C) precursor containing three metal components in step (1) is as follows: (a) A zinc-containing metal salt and an amino-containing organic ligand are dispersed in DMF solvent at a molar ratio of 1:2 to 2:1 to form a homogeneous mixed solution; (b) Triethylamine was added to the homogeneous mixed solution of step (a) to adjust the pH of the system to 7-8, and a colloidal suspension was obtained after stirring. (c) The colloidal suspension is subjected to centrifugation, washing with DMF solvent 3 to 5 times and methanol solvent 3 to 5 times in sequence, and then dried under vacuum at 60 to 80°C for 12 to 24 hours to obtain MOF(A) powder. (d) The MOF(A) powder and a substance containing a catalytic metal salt and a third metal salt are co-dispersed in DMF solvent to obtain a mixed solution, and the molar ratio of the catalytic metal salt and the third metal salt in the mixed solution is controlled to be 1:3 to 3:1; (e) The mixed solution from step (d) is ultrasonically dispersed for 20-60 min, then reacted under stirring for 2-5 h, the reaction product is separated by centrifugation, and dried under vacuum at 60-80 °C for 12-24 h to finally obtain the MOF(A,B,C) precursor containing two metal components.

7. The method for preparing a photothermal composite phase change material with built-in electric field-driven interfacial electron transfer according to claim 6, characterized in that, The zinc-containing metal salt includes one or more of zinc nitrate, zinc sulfate, zinc acetate, zinc chloride, and their hydrates; 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 third metal salt can be oxidized to metal oxides at high temperatures, including lanthanide metal salts such as cerium nitrate, cerium chloride, and cerium acetate, and their hydrates, as well as one or more of titanium tetrachloride, titanium oxysulfate, titanium trichloride, tin tetrachloride, tin sulfate, tin acetate, zirconium oxynitrate, zirconium oxychloride, zirconium acetate, aluminum nitrate nonahydrate, polyaluminum chloride, hafnium tetrachloride, yttrium nitrate, and yttrium chloride, and their hydrates.

8. The method for preparing a photothermal composite phase change material with built-in electric field-driven interfacial electron transfer according to claim 5, characterized in that, The specific method for preparing the ternary heterostructure carrier in step (2) is as follows: MOF (A,B,C) precursors containing three metal components were placed under an inert atmosphere and heated to 900-1200℃ at a heating rate of 1-5℃ / min. The precursors were then isothermally carbonized at this temperature for 2-6 hours to obtain a ternary heterostructure support.

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