A LaF3-based heterojunction electrode material and its preparation method and application

Abstract

The present invention belongs to the fields of materials science, nanotechnology and new energy, and particularly relates to a LaF3-based heterojunction electrode material, a preparation method thereof and an application. The LaF3-based heterojunction material is obtained by compounding the obtained LaF3 nanoparticles with other nano-morphology electrode materials through a microwave-assisted hydrothermal process; the LaF3 crystal structure of the LaF3 nanoparticles is hexagonal system, the space group is P-3c1, z = 6, and the micro-morphology is zero-dimensional nanoparticles; the other nano-morphology electrode materials are zero-dimensional nanoparticles, one-dimensional nanorods, one-dimensional nanowires, one-dimensional nanotubes, two-dimensional nanosheets or three-dimensional nano-materials. For the LaF3-based heterojunction electrode material of the present invention, due to the characteristics of high reaction activity of rare earth lanthanum element, high theoretical capacity value and working voltage of metal fluoride in the lanthanum fluoride electrode, after forming a heterojunction by compounding with another component, good synergistic effect can be exerted to significantly improve the electrochemical performance.

Description

Technical Field

[0001] The present invention belongs to the fields of material science, nanotechnology and new energy, and specifically relates to a LaF3-based heterojunction electrode material and a preparation method and application thereof. Background Art

[0002] Transition metal oxides, especially non-precious metal oxides such as iron, manganese, copper, aluminum, zinc, and tin, play a vital role in the field of electrochemical energy storage due to their advantages such as ideal theoretical specific capacity, cost-effectiveness, convenient synthesis, and multivalent chemical reactions. However, their commercial application is severely restricted by challenges such as their inherent low conductivity and low cycle stability. In addition, various carbon-based materials with advantages such as high conductivity, high specific surface area, good chemical stability, and low cost that are widely studied at present have broad application prospects in the field of energy storage batteries. However, various carbon-based materials exhibit the disadvantages of low capacity and low energy density due to the limitations of the double-layer mechanism, which affects their practical application. In view of the inherent defects of transition metal oxides or various carbon-based materials such as low material conductivity, slow kinetics, poor stability, or low capacity, at this stage, material composite strategies such as constructing heterojunctions can be used to utilize the synergistic effect between different nanostructure units in the composite to achieve modification of the physical and chemical properties of the material to improve its performance.

[0003] Metal fluoride materials have great application prospects in the fields of biomedicine, optoelectronics, etc. due to their unique physical and chemical properties, such as transparency in a wide spectral range, low phonon energy, good chemical stability, environmental protection, and low toxicity. Currently, there is no technology or literature related to the construction of LaF3-based heterojunction electrode materials and their application in the field of energy storage and conversion. Summary of the invention

[0004] The purpose of the present invention is to disclose a LaF3-based heterojunction electrode material and its preparation method and application. The LaF3 prepared by the microwave-assisted hydrothermal process of the present invention is a nanoparticle, which can be attached to various dimensional nano-morphological electrode materials to form a heterojunction. At the same time, due to the special chemical properties of LaF3 and the octahedral coordination mode, it can selectively adsorb or transmit reactive ions, thereby improving the storage and release capacity of the electrode material for specific ions. In addition, when it forms a heterojunction with other substances or participates in certain chemical reactions, it can form a specific spatial composite structure or produce highly reactive sites, play a good synergistic role, and can show excellent electrochemical performance.

[0005] The LaF3 component or both components in the LaF3-based heterojunction of the present invention are synthesized by a microwave-assisted hydrothermal process. By utilizing the characteristics of microwave heating reaction, the temperature is quickly raised to a reaction temperature of 120 to 150° C. under a power of 800 to 1100 W, and at a specific power and reaction temperature, a selective heating effect is exhibited to accelerate the nucleation and growth process, thereby greatly shortening the reaction time. At the same time, by regulating the nucleation and growth process of LaF3 or the product formation process, the LaF3 product particles are induced to nucleate and grow on the surface of another component of the heterojunction, thereby adjusting the heterogeneous interface properties of the composite material, thereby forming a specific heterojunction product.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a LaF3-based heterojunction electrode material, wherein the LaF3-based heterojunction electrode material is prepared by compounding LaF3 nanoparticles with other nano-morphology electrode materials through a microwave-assisted hydrothermal process; the LaF3 nanoparticles have a LaF3 crystal structure of a hexagonal system, a space group of P-3c1, z=6, and a microscopic morphology of zero-dimensional nanoparticles; and the other nano-morphology electrode materials are zero-dimensional nanoparticles, one-dimensional nanorods, one-dimensional nanowires, one-dimensional nanotubes, two-dimensional nanosheets or three-dimensional nanomaterials.

[0008] In the above technical solution, further, the other nano-morphology electrode materials are nano-morphology carbon materials or transition metal oxides of various dimensions; the transition metal oxides include unit or multi-unit non-precious transition metal oxides of iron, manganese, copper, aluminum, zinc, and tin.

[0009] In the above technical solution, further, the nano-morphological carbon materials of various dimensions include carbon quantum dots, carbon nanotubes, graphene or carbon nanohorns; the transition metal oxides include NiO, MnO2, Co3O4, NiMn2O4 or CoMn2O4.

[0010] Various carbon-based materials or transition metal oxides generally have high conductivity or multiple electrochemical reaction metal valence states, which can synergistically complement LaF3 to improve performance; various carbon-based materials or transition metal oxides have high microwave absorption and conversion capabilities (microwave dielectric loss tangent tanδ), which can efficiently absorb microwaves and convert them into internal energy, creating super hot spots on their surfaces and obtaining higher surface temperatures, which can promote LaF3 to adsorb and nucleate on their surfaces, thereby constructing heterojunction composite materials.

[0011] In the above technical solution, further, the preparation is carried out by microwave-assisted hydrothermal process, comprising the following steps:

[0012] (1) Preparation of precursor solution: fully mixing an aqueous solution containing a lanthanum source with a nano-morphological carbon material of various dimensions or a salt solution for preparing a transition metal oxide;

[0013] (2) Microwave hydrothermal and heat treatment process: The precursor solution is subjected to microwave hydrothermal reaction at a microwave power of 800-1100 W, the temperature is raised to 120-150 °C, and the reaction time is 1-3 h. The liquid after microwave reaction is centrifuged, washed, and dried to obtain the precursor;

[0014] (3) The precursor prepared in step (2) is sintered at 300-500° C. for 1-5 h under a protective atmosphere to obtain a LaF3-based heterojunction composite electrode material.

[0015] In the above technical solution, further, in step (1), the concentration of lanthanum ions is 15-25 mmol / L, the aqueous solution containing the lanthanum source contains urea and ammonium chloride, the urea concentration is 195-210 mmol / L, and the ammonium fluoride concentration is 65-75 mmol / L.

[0016] In the above technical solution, further, in step (1), the lanthanum source is lanthanum nitrate, lanthanum sulfate or lanthanum chloride.

[0017] In the above technical solution, further, in the step (1), the nano-morphological carbon or transition metal oxide of various dimensions has high microwave absorption conversion ability (microwave dielectric loss tangent tanδ), and after being mixed with the lanthanum source, the LaF3-based heterojunction material is prepared by a one-step microwave-assisted hydrothermal process using the strong microwave energy conversion ability of the nano-dimensional carbon materials or transition metal oxides.

[0018] In the above technical solution, further, in the step (2), before the microwave heating temperature reaches 100°C, heating is performed at a rate of 10-12°C / min, and after heating to 100°C, the heating is maintained for 5 minutes, and then the target temperature is reached at a rate of 5-8°C / min.

[0019] In the above technical solution, further, the heterojunction material obtained by the above one-step microwave-assisted hydrothermal process has a complete second phase structure in addition to the LaF3 phase structure.

[0020] The second aspect of the present invention provides the application of the aforementioned LaF3-based heterojunction electrode material in energy storage electrode materials and catalytic electrode materials.

[0021] In the above technical solution, further, the application is directly used as energy storage and catalytic electrode materials for supercapacitors, lithium batteries, fuel cells, zinc-air batteries or photocatalysis.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention provides a LaF3-based heterojunction electrode material and a preparation method and application thereof. The LaF3-based heterojunction electrode material can retain its original spatial structure and reactivity when compounded with other substances by utilizing its special physical and chemical properties, and can also modify the compounded substances, thereby achieving ideal electrochemical properties, and can be directly used as an energy storage and catalytic electrode material. The LaF3-based heterojunction electrode material of the present invention can play a good synergistic role after being compounded with another component to form a heterojunction, because of the characteristics of the high reactivity of the rare earth lanthanum element and the high theoretical capacity value and working voltage of the metal fluoride of the lanthanum fluoride electrode, and can achieve a significant improvement in electrochemical performance.

[0024] The LaF3-based heterojunction material prepared by the microwave-assisted hydrothermal method used in the present invention has the advantages of simple operation, short time cycle and low cost. The morphology and structure of the material can be regulated by controlling the reaction conditions. The prepared LaF3-based heterojunction material can be directly used as an electrode material and has excellent electrochemical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 XRD spectrum of the Co3O4 / LaF3 heterojunction material prepared in Example 1 of the present invention;

[0026] Figure 2 (a) Co3O4 / LaF3 heterojunction electrode material grown on nickel foam surface; Figure 2 (b) Co3O4 material grown on the surface of nickel foam;

[0027] Figure 3 (a) Co3O4 material grown on the surface of nickel foam; Figure 3 (b) Co3O4 / LaF3 heterojunction electrode material grown on the surface of nickel foam;

[0028] Figure 4 XRD pattern of the material prepared in the comparative example;

[0029] Figure 5 This is a SEM image of the NiMn2O4 / LaF3 heterojunction electrode material grown on the surface of nickel foam prepared in Example 2 of the present invention;

[0030] Figure 6 This is the SEM image of the CNT / LaF3 heterojunction prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0031] The technical solution of the invention is further described below in conjunction with the accompanying drawings and embodiments.

[0032] The following non-limiting examples are provided to enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way. The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0033] Example 1

[0034] This embodiment 1 is to form a Co3O4 / LaF3 heterojunction electrode material grown on the surface of nickel foam using LaF3 as the base through the above invention.

[0035] The chemicals used in this embodiment include nickel foam, 3M HCl, lanthanum nitrate, cobalt nitrate, ammonium fluoride, urea, anhydrous ethanol, and deionized water.

[0036] A method for preparing a Co3O4 / LaF3 heterojunction electrode material grown on the surface of nickel foam, specifically comprising the following steps:

[0037] (1) Pre-treat the nickel foam: cut the nickel foam into pieces with an area of ​​1×3 cm 2 , first use 3M HCl to soak and clean for 20 minutes, then use anhydrous ethanol and deionized water ultrasonic soak and clean for 15 minutes in turn to remove surface impurities, dry at 60°C for 6 hours and set aside.

[0038] (2) Accurately weigh 1 mmol of cobalt nitrate, 0.75 mmol of lanthanum nitrate, 2 mmol of ammonium fluoride, and 6 mmol of urea, add deionized water and prepare a 30 ml mixed uniform solution under magnetic stirring conditions.

[0039] (3) Soak the nickel foam pretreated in step (1) in the uniform solution in step (2) for 30 minutes.

[0040] (4) Pour the mixed solution of step (3) into a 100ml microwave hydrothermal reactor, tighten the reactor and place it in the microwave reactor, set the microwave reaction power to 900W, the temperature to 140°C, and the reaction time to 90min. After the reaction is completed, cool to room temperature and take out; before the microwave temperature reaches 100°C, heat at a rate of 10°C / min. After heating to 100°C, keep warm for 5min, and then reach 140°C at a rate of 5°C / min.

[0041] (5) The nickel foam after the reaction was ultrasonically cleaned 3 times with anhydrous ethanol and deionized water, each time for 3 minutes. It was then dried at 80°C for 12 hours under a vacuum of -0.1 MPa to obtain the Co3O4 / LaF3 precursor.

[0042] (6) The nickel foam obtained in step (5) (i.e., the Co3O4 / LaF3 precursor) is placed in a muffle furnace for heat treatment. The treatment process is to heat the nickel foam from room temperature to 50°C at a heating rate of 10°C / min under air, then heat the nickel foam to 400°C at a heating rate of 2°C / min and calcine for 3h. The nickel foam is then naturally cooled to room temperature to obtain a Co3O4 / LaF3 heterojunction electrode material grown on the surface of the nickel foam.

[0043] Application Examples

[0044] The Co3O4 / LaF3 heterojunction electrode material grown on the surface of nickel foam prepared in Example 1 was directly used as the working electrode, the platinum mesh was used as the counter electrode, and saturated calomel was used as the reference electrode to assemble a three-electrode test system with 6M KOH as the electrolyte for electrochemical performance testing.

[0045] Figure 1 This is the XRD spectrum of the Co3O4 / LaF3 heterojunction material prepared in Example 1 of the present invention. It can be found that the heterojunction materials with two complete phase structures of Co3O4 and LaF3 are obtained through a one-step microwave-assisted hydrothermal process.

[0046] The LaF3 crystal structure corresponds to the standard card PDF#77-2029; it is a hexagonal crystal system with a space group of P-3c1(165), z=6; the unit cell ;horn .

[0047] Figure 2 (a) is the Co3O4 / LaF3 heterojunction electrode material grown on the surface of nickel foam. Figure 2 (b) is the Co3O4 material grown on the surface of nickel foam; it can be seen from the two figures that the Co3O4 / LaF3 heterojunction material has improved the conductivity of the overall material compared to Co3O4 due to the introduction of LaF3, and the specific capacitance has been greatly improved, with better rate performance, and the potential window has been increased from 0.8V to 1.1V, thus verifying that LaF3-based supercapacitor heterojunction materials have excellent electrochemical properties such as wide potential window, high rate performance, and ultra-high specific capacitance.

[0048] Figure 3 (a) is the Co3O4 material grown on the surface of nickel foam. Figure 3 (b) is the Co3O4 / LaF3 heterojunction electrode material grown on the surface of nickel foam; Figure 3 As shown in (a), the single Co3O4 nanosheet has a nanowire morphology with the nanosheet end growing on it. Figure 3 As shown in (b), the microstructure of the Co3O4 / LaF3 heterojunction is LaF3 nanoparticles attached to the surface of Co3O4 nanosheets and nanowires. Figure 3As can be seen in (a), the presence of LaF3 nanoparticles forms a hierarchical morphology of nanosheets, nanowires, and nanoparticles, which is beneficial to the transport and diffusion of electrolyte ions.

[0049] Comparative Example

[0050] The difference from Example 1 is that the concentration of the raw materials in step (2) is changed, specifically: 1 mmol of cobalt nitrate, 0.8 mmol of lanthanum nitrate, 2.5 mmol of ammonium fluoride, and 6.5 mmol of urea are accurately weighed, and deionized water is added to prepare a 30 ml mixed uniform solution under magnetic stirring conditions.

[0051] Figure 4 The XRD spectrum of the material prepared in this comparative example. It can be found that compared with the Co3O4 / LaF3 heterojunction product obtained in Example 1, when the concentration is changed, the obtained product is a composite product of CoCo2O4 with a complete phase structure and only a partial diffraction crystal plane of LaF3, and LaF3 has significant lattice defects, such as the lack of diffraction crystal planes such as (300) and (113), the peak position of the (110) crystal plane is shifted to the left, and the relative intensity of the diffraction peaks of (110) and (002) changes.

[0052] Example 2

[0053] This embodiment 2 is to form a NiMn2O4 / LaF3 heterojunction electrode material grown on the surface of nickel foam using LaF3 as the base through the above invention.

[0054] The chemicals used in this embodiment include nickel foam, 3M HCl, nickel sulfate, potassium permanganate, lanthanum nitrate, ammonium fluoride, urea, anhydrous ethanol, and deionized water.

[0055] A method for preparing a NiMn2O4 / LaF3 heterojunction electrode material grown on the surface of nickel foam, specifically comprising the following steps:

[0056] (1) Pre-treat the nickel foam: cut the nickel foam into pieces with an area of ​​1×3 cm 2 , first use 3M HCl to soak and clean for 20 minutes, then use anhydrous ethanol and deionized water ultrasonic soak and clean for 15 minutes in turn to remove surface impurities, dry at 60°C for 6 hours and set aside.

[0057] (2) Accurately weigh 1 mmol nickel nitrate, 2 mmol potassium permanganate, 0.75 mmol lanthanum nitrate, 3 mmol ammonium fluoride, and 8 mmol urea, add deionized water and prepare a 40 ml mixed uniform solution under magnetic stirring.

[0058] (3) Soak the nickel foam pretreated in step (1) in the uniform solution in step (2) for 30 minutes.

[0059] (4) Pour the mixed solution of step (3) into a 100ml microwave hydrothermal reactor, tighten the reactor and place it in the microwave reactor, set the microwave reaction power to 800W, the temperature to 120°C, and the reaction time to 1h. After the reaction is completed, cool to room temperature and take out. Before the microwave temperature reaches 100°C, heat at a rate of 12°C / min. After heating to 100°C, keep warm for 5min, and then reach 120°C at 8°C / min.

[0060] (5) The nickel foam after the reaction was ultrasonically cleaned 3 times with anhydrous ethanol and deionized water, each time for 3 minutes. It was then dried at 80°C for 12 hours under a vacuum of -0.1 MPa to obtain the NiMn2O4 / LaF3 precursor.

[0061] (6) placing the nickel foam (i.e., NiMn2O4 / LaF3 precursor) obtained in step (5) into a muffle furnace for heat treatment,

[0062] The treatment process is to heat the sample from room temperature to 50°C at a rate of 10°C / min under nitrogen, and then heat the sample at a rate of 2°C / min.

[0063] The temperature was rapidly raised to 450°C and calcined for 2 h, and then naturally cooled to room temperature to obtain the NiMn2O4 / LaF3 heterojunction electrode material grown on the surface of nickel foam.

[0064] Figure 5 This is a SEM image of the NiMn2O4 / LaF3 heterojunction electrode material grown on the surface of nickel foam prepared in Example 2 of the present invention. From the figure, it can be found that the nano-particle LaF3 is supported and distributed on the surface of the NiMn2O4 nanosheets, forming a nanosheet / nanoparticle heterogeneous hierarchical microstructure. This morphology can effectively improve the utilization rate of both, while playing a good synergistic role, which is conducive to obtaining excellent electrochemical performance.

[0065] Example 3

[0066] This embodiment forms a heterojunction material CNT / LaF3 based on LaF3 through the above invention content.

[0067] The chemicals used in this example include commercial carbon nanotubes, HNO3 (65-68 wt%), lanthanum sulfate, ammonium fluoride, urea, anhydrous ethanol, and deionized water.

[0068] A method for preparing a CNT / LaF3 heterojunction electrode material comprises the following steps:

[0069] (1) First, 20 mg CNT (purity>95%, diameter 8-20 nm, length 5-30 µm) and 10 mL HNO3 (65-68 wt%) were mixed and transferred to a 50 mL ordinary hydrothermal reactor and heated to 180°C for 2 h. After cooling naturally to room temperature, vacuum filtration was performed until neutral, and then dried in a vacuum drying oven at 80°C for 8 h to obtain HNO3 acidified carbon nanotubes for later use.

[0070] (2) Accurately weigh 0.9 mmol of lanthanum sulfate, 3 mmol of ammonium fluoride, and 12 mmol of urea, add deionized water and prepare a 40 ml mixed uniform solution under magnetic stirring.

[0071] (3) Soak the carbon nanotubes pretreated in step (1) in the uniform solution prepared in step (2) for 30 minutes.

[0072] (4) Pour the mixed solution of step (3) into a 100ml microwave hydrothermal reactor, tighten the reactor and place it in the microwave reactor, set the microwave reaction power to 1100W, the temperature to 150°C, and the reaction time to 3h. After the reaction is completed, cool to room temperature and take out. Before the microwave temperature reaches 100°C, heat at a rate of 10°C / min. After heating to 100°C, keep warm for 5min, and then reach 150°C at 5°C / min.

[0073] (5) The reactants were ultrasonically cleaned three times with anhydrous ethanol and deionized water, each time for 3 minutes. They were then dried at 80°C for 12 hours under a vacuum of -0.1 MPa to obtain the CNT / LaF3 precursor.

[0074] (6) The precursor obtained in step (5) is placed in a muffle furnace for heat treatment. The treatment process is to heat the precursor from room temperature to 50°C at a heating rate of 10°C / min under air, then heat the precursor to 500°C at a heating rate of 2°C / min and calcine for 3 h. The precursor is then naturally cooled to room temperature to obtain a CNT / LaF3 heterojunction material.

[0075] Figure 6 This is a SEM image of the CNT / LaF3 heterojunction prepared in Example 3 of the present invention. It can be clearly found that the nanoparticle-like LaF3 is supported on the surface of the carbon nanotubes to form a nanowire / nanoparticle heterojunction morphology. The CNTs dispersed in the heterojunction can serve as a structural skeleton and conductive network, providing abundant growth sites for LaF3 attachment and constructing an excellent electron transport network. The CNT component and the LaF3 attached to the surface can synergistically produce a double-layer-pseudocapacitor energy storage reaction process, which is conducive to obtaining excellent electrochemical performance.

[0076] For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A LaF3-based heterojunction electrode material, characterized in that: The LaF3-based heterojunction electrode material is prepared by compounding LaF3 nanoparticles with other nano-morphology electrode materials through a microwave-assisted hydrothermal process; the LaF3 crystal structure of the LaF3 nanoparticles is a hexagonal system, the space group is P-3c1, z=6, and the microscopic morphology is a zero-dimensional nanoparticle; the other nano-morphology electrode materials are zero-dimensional nanoparticles, one-dimensional nanorods, one-dimensional nanowires, one-dimensional nanotubes, two-dimensional nanosheets or three-dimensional nanomaterials; the other nano-morphology electrode materials are transition metal oxides or nano-morphology carbon materials; the transition metal oxides include unit or multi-unit non-precious transition metal oxides of iron, manganese, copper, aluminum, zinc and tin; the transition metal oxides or nano-morphology carbon materials have high microwave absorption and conversion capabilities, and after being mixed with a lanthanum source, the LaF3-based heterojunction material is prepared through a one-step microwave-assisted hydrothermal process using their strong microwave energy conversion capabilities.

2. The LaF3-based heterojunction electrode material according to claim 1, characterized in that: The nano-morphology carbon material includes carbon quantum dots, carbon nanotubes, graphene or carbon nanohorns; the transition metal oxide includes NiO, MnO2, Co3O4, NiMn2O4 or CoMn2O4.

3. The LaF3-based heterojunction electrode material according to claim 1 is prepared by a microwave-assisted hydrothermal process, characterized in that: The following steps are involved: (1) Preparation of precursor solution: fully mixing an aqueous solution containing a lanthanum source with a nano-morphological carbon material or a salt solution for preparing a transition metal oxide; (2) Microwave hydrothermal and heat treatment process: The precursor solution is subjected to microwave hydrothermal reaction at a microwave power of 800-1100 W, the temperature is raised to 120-150 °C, and the reaction time is 1-3 h. The liquid after microwave reaction is centrifuged, washed, and dried to obtain the precursor; (3) The precursor prepared in step (2) is sintered at 300-500° C. for 1-5 h under a protective atmosphere to obtain a LaF3-based heterojunction composite electrode material.

4. The LaF3-based heterojunction electrode material according to claim 3, characterized in that: In step (1), the concentration of lanthanum ions is 15 to 25 mmol / L, and the aqueous solution containing the lanthanum source contains urea and ammonium chloride, wherein the concentration of urea is 195 to 210 mmol / L and the concentration of ammonium fluoride is 65 to 75 mmol / L; in step (1), the lanthanum source is lanthanum nitrate, lanthanum sulfate or lanthanum chloride.

5. The LaF3-based heterojunction electrode material according to claim 3, characterized in that: In the step (2), the microwave heating temperature is heated at a rate of 10-12 °C / min before reaching 100 °C. After heating to 100 °C, the temperature is kept for 5 min, and then the target temperature is reached at a rate of 5-8 °C / min.

6. The LaF3-based heterojunction electrode material according to claim 3, characterized in that: In addition to the LaF3 phase structure, the heterojunction material prepared by microwave-assisted hydrothermal process also coexists with a complete second phase structure.

7. Use of the LaF3-based heterojunction electrode material according to any one of claims 1 to 6 in energy storage electrode materials or catalytic electrode materials.

8. The use according to claim 7, characterized in that: The application is directly used as an electrode material for supercapacitors, lithium batteries, fuel cells, zinc-air batteries or photocatalysis.

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