A photothermal synergistic phase change composite thin film based on heterostructure and its preparation method

Abstract

This invention discloses a photothermal synergistic phase change composite thin film based on a heterostructure and its preparation method, belonging to the technical field of nanomaterials and composite phase change materials. The composite thin film includes a heterostructured photothermal carrier film and a phase change material confined and loaded thereon. The heterostructured photothermal carrier film uses manganese oxide coated with a carbon layer as a framework, with heterostructured functional units composed of metal particles constructed in situ on its surface. Sodium manganate, as a precursor film for the heterostructure construction, is modified with a metal-organic coordination structure and derivatized in an inert atmosphere to form a heterostructure interface on its surface where the carbon layer and metal particles are coupled in situ, further confining and loading the phase change material. The carbon layer and metal particles form a tightly contacted interface structure on the manganese oxide surface, which enhances light absorption and regulates heat conduction behavior under illumination, thereby achieving efficient conversion of light energy into heat energy and synergistically completing the storage and release of heat energy with the phase change material. This invention effectively improves the photothermal conversion efficiency and thermal energy utilization performance of composite films by constructing a heterogeneous structure interface coupling carbon layers and metal particles. The resulting composite film has rapid heating, stable heat storage and good cycle stability, and has good application prospects in the fields of solar thermal storage and thermal management.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials and composite phase change materials, specifically relating to a photothermal synergistic phase change composite thin film based on a heterostructure and its preparation method. Background Technology

[0002] Solar energy, as a clean, renewable, and green energy source, has been widely applied in photovoltaics, photocatalysis, water purification, and other fields. However, the inherent intermittency and variability of solar radiation pose a significant challenge to the stable utilization of solar energy. Storing solar energy as heat through phase change materials (PCMs) holds great promise, relying on the high energy density and relatively stable phase change temperature exhibited by PCMs during the phase change process, enabling continuous energy release even in the absence of solar radiation. However, single PCMs generally suffer from insufficient solar light absorption and low photothermal conversion efficiency, severely limiting their application in the field of solar thermal utilization. Therefore, introducing high-efficiency photothermal materials into PCM systems to achieve synergistic enhancement of photothermal conversion and phase change energy storage has become a research hotspot in this field.

[0003] Among existing photothermal material systems, nano-carbon materials, metal-based materials, and organic photothermal materials have been extensively studied. Nano-carbon materials, in particular, have shown great potential for improving the photothermal performance of phase change materials due to their excellent light absorption, thermal stability, and chemical stability. However, traditional carbon materials often suffer from uneven pore structure distribution, limited interface control capabilities, and insufficient contact efficiency with phase change materials, making it difficult to achieve efficient synergy between photothermal conversion and thermal energy storage in composite systems.

[0004] In recent years, manganese-based oxide materials have been considered promising photothermal functional materials due to their unique semiconductor properties, wide spectral response range, and good thermal stability. In particular, manganese-based oxides are easy to construct one-dimensional nanostructures such as nanowires and nanoribbons, providing a favorable structural basis for light absorption and heat conduction. However, single manganese-based oxide materials still suffer from limited light absorption efficiency, significant surface reflection loss, and rapid thermal relaxation during photothermal conversion, making it difficult to meet the requirements of efficient photothermal energy storage applications.

[0005] To further enhance the photothermal performance of manganese-based oxide materials, researchers have attempted to introduce carbon materials or metal nanoparticles onto their surfaces to improve light absorption or thermal conductivity. However, in existing technologies, carbon materials and metal components are often dispersed, with weak interfacial bonding, making it difficult to form a stable and efficient synergistic interface on the manganese-based oxide surface, thus limiting the effectiveness of photothermal enhancement. Furthermore, phase change materials in this type of composite system still face challenges such as insufficient confinement and low interfacial heat transfer efficiency.

[0006] Therefore, how to construct a heterogeneous interface formed by the tight coupling of carbon layers and metal particles on the surface of manganese oxides, and on this basis achieve synergistic enhancement of photothermal conversion and phase change energy storage, remains a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a photothermal synergistic phase change composite thin film based on a heterostructure and its preparation method. By constructing a heterostructure photothermal carrier formed by the tight coupling of a carbon layer and metal particles in situ on the surface of manganese oxide, the synergistic optimization of light absorption enhancement, heat conduction behavior regulation, and phase change energy storage process is achieved, thereby significantly improving the photothermal conversion efficiency and thermal energy utilization performance of the composite thin film.

[0008] This invention provides a photothermal synergistic phase change composite thin film based on a heterostructure and its preparation method, the method comprising the following steps: (1) Sodium manganate film is immersed in alcohol solution containing metal ions to allow metal ions to adsorb or penetrate into the precursor film. Then the precursor film is placed in solution containing organic ligands for in-situ reaction to obtain film modified with metal-organic coordination structure. (2) After drying the film obtained in step (1), it is calcined at high temperature under an inert atmosphere to construct a manganese oxide / metal / carbon heterostructure support film in situ, wherein the sodium manganate structure is converted into a manganese oxide structure after calcination. (3) Load the phase change material into the heterogeneous photothermal carrier film to obtain a photothermal synergistic phase change composite film.

[0009] The following method was used to prepare metal-organic coordination structure modified thin films: (1) Disperse 0.5-2 g of metal salt in methanol solvent to form a homogeneous mixed solution A; disperse 0.5-2 g of organic ligand in methanol solvent to form a homogeneous mixed solution B. (2) Add sodium manganate precursor film to the homogeneous mixed solution A in step (1), and then incubate in a water bath at 50~60℃ for 1~2h to obtain precursor film; then add the above precursor film to the homogeneous mixed solution B, and then incubate in a water bath at 20~40℃ for 12~24h. (3) The film after the reaction in step (2) is rinsed three to four times with methanol solution, and then dried at 60~80℃ for 2~4h to finally obtain the film modified with metal-organic coordination structure.

[0010] The following method was used to synthesize manganese oxide / metal / carbon heterostructure support films: The metal-organic coordination structure modified film was placed under an inert atmosphere and heated to 400-700℃ at a heating rate of 1-5℃ / min. It was then carbonized at this temperature for 2-6 hours to finally obtain the manganese oxide / metal / carbon heterostructure support.

[0011] The photothermal synergistic phase change composite film was prepared using the following method: The manganese oxide / metal / carbon heterostructure carrier film prepared above was dropped with excess octadecyl alcohol and dried in a vacuum drying oven at 80°C for 24 hours to ensure complete contact and thorough mixing. Then, the film was placed on an 80°C hot stage and the excess octadecyl alcohol was absorbed by filter paper to obtain a photothermal synergistic phase change composite film.

[0012] The metal salts applicable to this invention include one or more of the following: zinc nitrate, zinc sulfate, zinc acetate, zinc chloride, nickel nitrate, nickel sulfate, nickel acetate, nickel chloride, cobalt nitrate, cobalt chloride, cobalt sulfate, cobalt acetate, ferric nitrate, ferric chloride, ferric sulfate, and ferric acetate.

[0013] The metal salts suitable for use in this invention include: 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-butylimidazole, and 2-hydroxyethylimidazole.

[0014] The organic phase change materials applicable to this invention include one or more of the following: n-octanol, n-decanol, octadecanol, lauryl alcohol, myristol, palmitol, octadecanol, cetearyl alcohol, behenol, and polyethylene glycol.

[0015] The beneficial effects of this invention are as follows: (1) The present invention significantly enhances the absorption capacity of the composite film to sunlight and improves the conversion efficiency of light energy to heat energy by constructing a heterostructure interface between a carbon layer and metal particles in situ on the surface of a manganese oxide nanostructure. (2) The constructed heterostructure can effectively regulate the heat conduction behavior in the composite system, reduce the disorder relaxation and loss of heat energy in the carrier, and facilitate the accumulation and storage of heat energy in the phase change material. (3) The multi-scale framework formed by manganese oxide nanostructures provides a good confinement space for phase change materials, which improves the structural stability and cycle reliability of phase change materials during repeated phase change processes. (4) The preparation method of the present invention mainly consists of soaking, in-situ reaction and inert atmosphere calcination. The process is simple, highly controllable, and suitable for large-scale preparation. (5) The resulting photothermal synergistic phase change composite film has the advantages of rapid heating, stable heat storage and reusability, and has good application prospects in the fields of solar thermal storage, thermal management and related energy utilization. Attached Figure Description

[0016] 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.

[0017] Figure 1 This is the TEM image of the carrier material obtained in Embodiment 1 of the present invention.

[0018] Figure 2 The image shows the XRD pattern of the carrier material obtained in Embodiment 1 of this invention.

[0019] Figure 3 The XRD pattern of the phase change composite film obtained in Embodiment 1 of the present invention is shown.

[0020] Figure 4 The image shows the DSC spectrum of the phase change composite membrane obtained in Embodiment 1 of this invention.

[0021] Figure 5 The image shows the DSC spectrum of the phase change composite membrane obtained in Embodiment 1 of this invention after 200 cycles.

[0022] Figure 6 The photothermal temperature change curve of the phase change composite film obtained in Embodiment 1 of the present invention is shown.

[0023] Figure 7 The photothermal temperature change curve of the phase change composite film obtained in Embodiment 2 of the present invention is shown.

[0024] Figure 8 The photothermal temperature change curve of the phase change composite film obtained in Embodiment 3 of the present invention is shown. Detailed Implementation

[0025] 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.

[0026] 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.

[0027] Implementation Case 1 Preparation of manganese oxide / metal / carbon heterostructure carrier thin film materials: 1 g of cobalt nitrate hexahydrate was dispersed in methanol to form a homogeneous cobalt nitrate solution; 1 g of dimethylimidazole was dispersed in methanol to form a homogeneous imidazole solution. A sodium manganate precursor film was added to the homogeneous cobalt nitrate solution, and the mixture was then incubated in a water bath at 50°C for 1 hour to obtain a precursor film. This precursor film was then added to the homogeneous imidazole solution, and the mixture was incubated in a water bath at 30°C for 24 hours. The reacted film was washed three times with methanol solution and then dried at 60°C for 2 hours to obtain a metal-organic coordination structure modified film. The metal-organic coordination structure modified film was placed under an inert atmosphere and heated to 500°C at a programmed heating rate of 2°C / min, and then carbonized at this temperature for 4 hours to finally obtain a manganese oxide / metal / carbon heterostructure support film.

[0028] Preparation of photothermal synergistic phase change composite films: The manganese oxide / metal / carbon heterostructure carrier film prepared above was dropped with excess octadecyl alcohol and dried in a vacuum drying oven at 80°C for 24 hours to ensure complete contact and thorough mixing. Then, the film was placed on an 80°C hot stage and the excess octadecyl alcohol was absorbed by filter paper to obtain a photothermal synergistic phase change composite film.

[0029] Test results show that Figure 1 The TEM image clearly shows a manganese oxide / cobalt / carbon heterostructure. Figure 2 The XRD results show that the characteristic peaks of the support at 44.2°, 51.5°, and 75.8° correspond to those of cobalt nanoparticles, while those at 34.9°, 40.5°, 58.7°, 70.1°, and 73.7° correspond to those of manganese oxide nanowires. Figure 3 The XRD results of the composite phase change material clearly show the characteristic peak of octadecyl alcohol, confirming that the 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 case are as follows: Figure 4 As shown, the composite phase change material has a core material loading rate of 81.2%, a melting temperature of 61.0℃, a melting enthalpy of 187.2 J / g, a solidification temperature of 54.2℃, and a solidification enthalpy of 179.3 J / g. Furthermore, after 200 cycles, the phase change temperature and enthalpy show no significant changes, demonstrating excellent thermal cycling stability. The photothermal data curves of the phase change composite film are shown below. Figure 6 As shown, under the simulated light intensity of one standard sun, the temperature of the lower surface of the phase change composite film rises to 50°C within 30 seconds, and the photothermal conversion efficiency of the phase change composite film is as high as 92.0%, which confirms that the prepared phase change composite film has excellent photothermal conversion performance.

[0030] Implementation Case 2 Preparation of manganese oxide / nickel / carbon heterostructure carrier thin film materials: 1g of nickel nitrate was dispersed in methanol solvent to form a homogeneous mixed nickel nitrate solution; 1 g of dimethylimidazole was dispersed in methanol to form a homogeneous mixed imidazole solution. A manganese-based oxide precursor film was added to the homogeneous mixed nickel nitrate solution, followed by incubation at 50°C for 1 h in a water bath to obtain the precursor film. This precursor film was then added to the homogeneous mixed imidazole solution, followed by incubation at 30°C for 24 h in a water bath. The reacted film was washed three times with methanol solution and then dried at 60°C for 2 h to obtain a metal-organic coordination structure modified film. The metal-organic coordination structure modified film was placed under an inert atmosphere and heated to 500°C at a programmed rate of 2°C / min, and then carbonized at this temperature for 4 h to finally obtain a manganese oxide / nickel / carbon heterostructure support film.

[0031] Preparation of photothermal synergistic phase change composite films: Excess octadecyl alcohol was added dropwise to the heterostructured manganese oxide / nickel coupled carbon hybrid film support prepared above, and the film was dried in a vacuum drying oven at 80℃ for 24 h to ensure complete contact and thorough mixing. Then, the excess octadecyl alcohol was absorbed by filter paper on an 80℃ hot stage to obtain a photothermal synergistic phase change composite film. Test results show that under simulated standard sunlight intensity, the lower surface temperature of the phase change composite film rises to 50℃ within 35 s, and the photothermal conversion efficiency of the phase change composite film is as high as 89.2%, confirming that the prepared phase change composite film has excellent photothermal conversion performance.

[0032] Implementation Case 3 Preparation of manganese oxide / zinc / carbon heterostructure carrier thin film materials: 1 g of zinc nitrate was dispersed in methanol to form a homogeneous mixed zinc nitrate solution; 1 g of dimethylimidazole was dispersed in methanol to form a homogeneous mixed imidazole solution. A manganese-based oxide precursor film was added to the homogeneous mixed zinc nitrate solution, and then incubated in a water bath at 50°C for 1 h to obtain a precursor film. This precursor film was then added to the homogeneous mixed imidazole solution, and incubated in a water bath at 30°C for 24 h. The reacted film was washed three times with methanol solution and then dried at 60°C for 2 h to obtain a metal-organic coordination structure modified film. The metal-organic coordination structure modified film was placed under an inert atmosphere and heated to 500°C at a programmed heating rate of 2°C / min, and then carbonized at this temperature for 4 h to finally obtain a manganese oxide / zinc / carbon heterostructure support film.

[0033] Preparation of photothermal synergistic phase change composite films: The prepared manganese oxide / zinc / carbon heterostructure carrier film was dropwise with excess octadecyl alcohol and dried in a vacuum drying oven at 80°C for 24 hours to ensure complete contact and thorough mixing. Then, the film was placed on an 80°C hot stage and the excess octadecyl alcohol was absorbed by filter paper to obtain a photothermal synergistic phase change composite film.

[0034] Test results show that under simulated standard sunlight intensity, the lower surface temperature of the phase change composite film rises to 50℃ within 50s, and the photothermal conversion efficiency of the phase change composite film is as high as 88.2%, confirming that the prepared phase change composite film has excellent photothermal conversion performance.

Claims

1. A photothermal synergistic phase change composite thin film based on a heterostructure, characterized in that, It includes a carbon coating layer, a carbon-coated manganese oxide nanowire framework, and metal nanoparticles coupled to the carbon-coated manganese oxide nanowires; the carbon coating layer, metal nanoparticles, and manganese oxide framework are coupled to form a heterogeneous thin film carrier.

2. The photothermal synergistic phase change composite thin film based on a heterostructure according to claim 1, characterized in that, The heterostructured thin film carrier forms a continuous electron transport network through a carbon-coated manganese oxide nanowire framework. The metal nanoparticles generate electromagnetic field enhancement in the visible-near infrared region through localized surface plasmon resonance. The manganese oxide nanowires enhance the response in the ultraviolet-visible region through interband transitions and defect state absorption.

3. The photothermal synergistic phase change composite thin film based on a heterostructure according to claim 1, characterized in that, The heterostructured thin film carrier has a heterogeneous interface, and the heterogeneous interface has a built-in electric field that promotes electron transfer.

4. The photothermal synergistic phase change composite thin film based on a heterostructure according to claim 3, characterized in that, There is a Fermi level difference at the heterogeneous interface; the built-in electric field is induced by the Fermi level difference and can drive the transfer of electrons between the carbon layer and manganese oxide, and between the metal nanoparticles and manganese oxide. Manganese oxide has abundant oxygen vacancies and can capture electrons.

5. A method for preparing a photothermal synergistic phase change composite thin film based on a heterostructure, characterized in that, Includes the following steps: (1) Sodium manganate film is immersed in alcohol solution containing metal ions to allow metal ions to adsorb or penetrate into the precursor film. Then the precursor film is placed in solution containing organic ligands for in-situ reaction to obtain film modified with metal-organic coordination structure. (2) After drying the film obtained in step (1), it is calcined at high temperature under an inert atmosphere to construct a manganese oxide / metal / carbon heterostructure support film in situ, wherein the sodium manganate structure is converted into a manganese oxide structure after calcination. (3) Add excess octadecyl alcohol to the manganese oxide / metal / carbon heterostructure carrier film prepared in step (2), dry it in a vacuum drying oven at 80°C for 24 hours to ensure complete contact and thorough mixing, and then use filter paper to absorb excess octadecyl alcohol on the film on an 80°C hot stage to obtain a photothermal synergistic phase change composite film.

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 specific method for preparing the metal-organic coordination structure modified thin film obtained in step (1) is as follows: (a) Disperse a metal salt in methanol solvent at a weight of 0.5 to 2 g to form a homogeneous mixed solution A; disperse an organic ligand in methanol solvent at a weight of 0.5 to 2 g to form a homogeneous mixed solution B; (b) Add sodium manganate film to the homogeneous mixed solution A from step (a), and then incubate in a water bath at 50-60°C for 1-2 hours to obtain precursor film; Then the above precursor film was added to the homogeneous mixed solution B, and then incubated in a water bath at 20-40°C for 12-24 hours. (c) The film after the reaction in step (b) is washed three to four times with methanol solution, and then dried at 60 to 80 °C for 2 to 4 hours to finally obtain the film modified with metal-organic coordination structure.

7. 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 manganese oxide / metal / carbon heterostructure carrier film obtained in step (2) is as follows: the metal-organic coordination structure modified film is placed under an inert atmosphere and heated to 400-700℃ at a heating rate of 1-5℃ / min, and carbonized at this temperature for 2-6 hours to finally obtain the manganese oxide / metal / carbon heterostructure carrier film.

8. The method for preparing a photothermal synergistic phase change composite thin film based on a heterostructure according to claim 5, characterized in that, The phase change material includes, but is not limited to, one or more of n-octanol, n-decanol, octanol-decanol, lauryl alcohol, myristol, palmitol, octadecanol, cetearyl alcohol, behenol, and polyethylene glycol.

9. The method for preparing a photothermal synergistic phase change composite thin film based on a heterostructure according to claim 6, characterized in that, The metal salt includes, but is not limited to, one or more of zinc nitrate, zinc sulfate, zinc acetate, zinc chloride, nickel nitrate, nickel sulfate, nickel acetate, nickel chloride, cobalt nitrate, cobalt chloride, cobalt sulfate, cobalt acetate, ferric nitrate, ferric chloride, ferric sulfate, and ferric acetate.

10. The method for preparing a photothermal synergistic phase change composite thin film based on a heterostructure according to claim 6, characterized in that, The organic ligand includes, but is not limited to, one or more of 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-butylimidazole, and 2-hydroxyethylimidazole.

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