CoFe-LDH-MOFs composite material and preparation method and application thereof
Patent Information
- Application Number
- CN202510730483.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-03
- Publication Date
- 2025-09-09
Smart Images
Figure CN120607290A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of nanomaterial preparation, and in particular to a CoFe-LDH@MOFs composite material and a preparation method and application thereof. Background Art
[0002] With the continuous growth of modern energy demand and the urgent pursuit of efficient and sustainable energy storage technologies, supercapacitors have emerged in many energy storage fields due to their advantages such as high power density, fast charge and discharge characteristics and long cycle life. However, the relatively low energy density has seriously hindered the widespread application of supercapacitors in various fields. Therefore, it is crucial to explore high-energy-density supercapacitor electrode materials. At present, many electrode materials have been developed. Among them, metal-organic framework materials (MOFs) have become important materials in the field of supercapacitors due to their unique advantages such as ultra-high specific surface area, adjustable pore structure and customizable metal-ligand combination. However, MOFs still have inherent defects such as poor conductivity and insufficient stability, which seriously restrict their practical application in supercapacitors.
[0003] To address these issues, various strategies have been proposed to construct MOF-based materials with enhanced functionality or novel properties to achieve superior performance in various applications: (a) modulating metal nodes and ligands; (b) obtaining derivatives through post-processing; and (c) forming composites with other materials. Composites have been widely used in supercapacitors due to their facile preparation and ease of control. Existing technologies often combine them with two-dimensional materials such as conductive carbon materials (e.g., graphene, carbon nanotubes), conductive polymers (e.g., polyaniline), metal oxides / sulfides (e.g., RuO2, Co3O4), or MXene. However, these composites still have significant drawbacks: conductive carbon materials tend to clog MOF pores and increase cost; conductive polymers have poor cycling stability and rely on acidic environments; metal oxides are expensive and suffer from volume expansion issues; and MXene preparation is dangerous and prone to oxidative degradation. Furthermore, these composites suffer from common issues such as weak interfacial bonding, complex processing, and insufficient cycle life, which hinder their practical application. Summary of the Invention
[0004] The purpose of the present invention is to provide a CoFe-LDH@MOFs composite material, a preparation method and application thereof. The CoFe-LDH@MOFs composite material is synthesized using a ligand-assisted conversion strategy with CoFe-LDH as a matrix. The prepared composite material has excellent capacitance performance and can be used as an electrode material for supercapacitors. The preparation method is simple and does not require an additional metal source. At the same time, the conversion process of LDHs to MOFs can be regulated.
[0005] To achieve the above object, the present invention provides a method for preparing a CoFe-LDH@MOFs composite material, comprising the following steps:
[0006] (1) adding nickel foam to deionized water containing a cobalt source, an iron source, urea, and ammonium fluoride, placing the mixture in an autoclave for hydrothermal reaction, and washing and drying to obtain CoFe-LDH grown on the nickel foam;
[0007] (2) The nickel foam loaded with CoFe-LDH was added to an N,N-dimethylformamide solution containing terephthalic acid, placed in an autoclave for hydrothermal reaction, and washed and dried to obtain a CoFe-LDH@MOFs composite material.
[0008] Preferably, in step (1), the molar volume ratio of the cobalt source, the iron source, urea, ammonium fluoride and deionized water is: (0.5-1.5) mmol: (0.25-0.75) mmol: (5-15) mmol: (2-6) mmol: 30 mL.
[0009] Preferably, in step (1), the cobalt source is cobalt nitrate hexahydrate, and the iron source is ferric nitrate nonahydrate.
[0010] Preferably, in step (1), the temperature of the hydrothermal reaction is 100-140° C., and the time of the hydrothermal reaction is 4-8 hours.
[0011] Preferably, in step (1), the solvents used for washing are deionized water and anhydrous ethanol.
[0012] Preferably, in step (2), the molar volume ratio of terephthalic acid and N,N-dimethylformamide solution is: (0.5-1.5) mmol:30 mL.
[0013] Preferably, in step (2), the temperature of the hydrothermal reaction is 140-180° C., and the time of the hydrothermal reaction is 8-12 h.
[0014] Preferably, in step (2), the solvents used for washing are N,N-dimethylformamide and anhydrous ethanol.
[0015] The present invention also provides a CoFe-LDH@MOFs composite material prepared by the above preparation method.
[0016] The present invention also provides the use of the CoFe-LDH@MOFs composite material in preparing a supercapacitor.
[0017] Layered double hydroxides (LDHs), composed of positively charged host layers and intercalated anions, are an important class of two-dimensional (2D) layered materials. They have the potential to expose active sites, provide anchoring points, balance various charges, and, after exfoliation, serve as guest molecule matrices, reducing charges and thus electron-hole binding. Therefore, in situ generation of MOFs using supported LDH substrates can significantly improve the electrochemical activity and photochemical properties of the materials. Furthermore, the ligand-assisted conversion method offers a simple synthesis method, does not require an additional metal source, and can regulate the conversion process of LDHs to MOFs. For example, LDHs / MOFs or pure MOFs with varying degrees of conversion can be obtained by adjusting the ligand concentration or reaction time.
[0018] As a matrix and precursor, LDHs provide anchoring active centers and metal sources for the nucleation and growth of MOFs, effectively preventing MOF aggregation. Simultaneously, the surface area and porosity of the resulting MOFs are significantly increased, exposing more accessible active centers and accelerating the rates of electron transfer and mass diffusion. Therefore, the preparation of LDHs / MOFs composites using LDHs can improve the defects of supercapacitors.
[0019] Therefore, the present invention utilizes a ligand-assisted conversion method to prepare the CoFe-LDH@MOFs composite material. This method is simple, requires no additional metal source, and can regulate the conversion of LDHs to MOFs. The resulting composite material exhibits excellent capacitance performance and has promising applications in supercapacitors.
[0020] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 This is a surface morphology of the CoFe-LDH loaded nickel foam prepared in Example 1;
[0022] Figure 2 This is the surface morphology of CoFe-LDH@MOFs-8h prepared in Example 2;
[0023] Figure 3 This is the surface morphology of CoFe-LDH@MOFs-10h prepared in Example 1;
[0024] Figure 4 This is the surface morphology of CoFe-LDH@MOFs-12h prepared in Example 3;
[0025] Figure 5 Cyclic voltammetry curves of the electrodes prepared in Example 1, Example 2 and Example 3 in 2M KOH electrolyte;
[0026] Figure 6 The constant current charge-discharge curves of the electrodes prepared in Example 1, Example 2 and Example 3 in 2M KOH electrolyte;
[0027] Figure 7 The relationship between the specific capacitance of the electrodes prepared in Example 1, Example 2 and Example 3 and different current densities in 2M KOH electrolyte;
[0028] Figure 8 The CoFe-LDH@MOFs-10h in Example 1 was 2 Cycling stability diagram at current density of . DETAILED DESCRIPTION
[0029] The technical solution of the present invention is further described below by means of the accompanying drawings and examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. Any other changes, modifications, substitutions, combinations, and simplifications made without violating the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the protection scope of the present invention. In addition, it should be understood that after reading the contents of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application and belong to the scope of protection of the present invention.
[0030] References to "embodiments" herein mean that the specific features, structures, or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the word "embodiment" in various places in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or relevance to other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the various technical features mentioned in the embodiments can be combined in any manner to form a corresponding implementable technical solution.
[0031] Unless otherwise defined, the technical terms used herein have the same meanings as those generally understood by those skilled in the art to which this application belongs; the use of relevant terms herein is only for describing specific embodiments and is not intended to limit this application.
[0032] Unless otherwise specified in the present invention, the materials, reagents, instruments, equipment and performance testing methods used are those commonly used by those skilled in the art.
[0033] Example 1
[0034] This embodiment provides a method for preparing a CoFe-LDH@MOFs composite material, comprising the following steps:
[0035] (1) 1 mmol of cobalt nitrate hexahydrate (Co(NO3)3·6H2O), 0.5 mmol of ferric nitrate nonahydrate (Fe(NO3)3·9H2O), 10 mmol of urea (CH4N2O), and 4 mmol of ammonium fluoride (NH4F) were dissolved in 30 mL of deionized water to obtain a uniform mixed solution. Subsequently, the obtained solution was transferred to a 100 mL autoclave and the pre-treated nickel foam (1×1 cm 2 ) was immersed therein and heated at 120°C for 6 hours; after the reaction was completed, it was cooled to room temperature and the foamed nickel was repeatedly washed with deionized water and anhydrous ethanol; finally, it was vacuum dried at 60°C for 6 hours to obtain foamed nickel loaded with CoFe-LDH.
[0036] (2) 1 mmol of terephthalic acid (H2BDC) was dissolved in 30 mL of N,N-dimethylformamide (DMF) solution to obtain a uniform solution; then, the solution was transferred to a 100 mL autoclave, and the prepared nickel foam loaded with CoFe-LDH was immersed in the solution and kept at 160°C for 10 hours; after the reaction was completed, the autoclave was naturally cooled to room temperature, and the nickel foam loaded with the composite material was repeatedly washed several times with DMF and anhydrous ethanol in turn, and finally dried at 60°C for 6 hours to obtain the CoFe-LDH@MOFs-10h composite material.
[0037] Example 2
[0038] This embodiment provides a method for preparing a CoFe-LDH@MOFs composite material, comprising the following steps:
[0039] (1) Same as Example 1, no further details will be given here.
[0040] (2) 1 mmol of terephthalic acid (H2BDC) was dissolved in 30 mL of N,N-dimethylformamide (DMF) solution to obtain a uniform solution; then, the solution was transferred to a 100 mL autoclave, and the prepared nickel foam loaded with CoFe-LDH was immersed in the solution and kept at 160°C for 8 hours; after the reaction was completed, the autoclave was naturally cooled to room temperature, and the nickel foam loaded with the composite material was repeatedly washed several times with DMF and anhydrous ethanol in turn, and finally dried at 60°C for 6 hours to obtain the CoFe-LDH@MOFs-8h composite material.
[0041] Example 3
[0042] This embodiment provides a method for preparing a CoFe-LDH@MOFs composite material, comprising the following steps:
[0043] (1) Same as Example 1, no further details will be given here.
[0044] (2) 1 mmol of terephthalic acid (H2BDC) was dissolved in 30 mL of N,N-dimethylformamide (DMF) solution to obtain a uniform solution; then, the solution was transferred to a 100 mL autoclave, and the prepared nickel foam loaded with CoFe-LDH was immersed in the solution and kept at 160°C for 12 hours; after the reaction was completed, the autoclave was naturally cooled to room temperature, and the nickel foam loaded with the composite material was repeatedly washed several times with DMF and anhydrous ethanol in turn, and finally dried at 60°C for 6 hours to obtain the CoFe-LDH@MOFs-12h composite material.
[0045] Figure 1 The figure shows the surface morphology of the nickel foam loaded with CoFe-LDH prepared in Example 1; it can be seen from the figure that the sample has a good nanoflower morphology.
[0046] Figure 2 The figure shows the surface morphology of CoFe-LDH@MOFs-8h prepared in Example 2. It can be seen from the figure that MOFs nanosheets grow evenly on the surface of CoFe-LDH nanopetals, forming a unique heterogeneous structure morphology.
[0047] Figure 3 The figure shows the surface morphology of CoFe-LDH@MOFs-10h prepared in Example 1. It can be seen from the figure that the size of the MOFs nanosheets is significantly increased, forming a heterostructure morphology in which nanoflowers and nanosheets are intertwined.
[0048] Figure 4 The figure shows the surface morphology of CoFe-LDH@MOFs-12h prepared in Example 3. It can be seen from the figure that the size and thickness of the MOFs nanosheets are further increased. This structural change may reduce the contact efficiency between the material and the electrolyte and hinder ion transport.
[0049] The samples prepared in Examples 1, 2, and 3 were used as electrode materials to conduct electrochemical performance tests. The specific test methods are as follows:
[0050] The electrochemical performance of the sample materials was tested using a standard three-electrode system, with nickel foam loaded with electrode materials as the working electrode, a mercury / mercuric oxide electrode as the reference electrode, a platinum sheet as the counter electrode, and a 2M KOH solution as the electrolyte.
[0051] Figure 5The cyclic voltammetry (CV) curves of the electrode materials prepared in Examples 1, 2 and 3 above are in the voltage window of 0-0.6V at a scan rate of 5mV / s. It can be clearly seen from the figure that a pair of obvious symmetrical redox peaks are observed in all CV curves, indicating that they have pseudocapacitive characteristics. The CoFe-LDH@MOFs-10h composite material prepared in Example 1 of the present invention exhibits better energy storage characteristics in the electrochemical performance test than the CoFe-LDH material prepared in Example 1, which is specifically manifested in an increase in the closed area of the cyclic voltammetry test curve. This performance improvement is mainly attributed to the synergistic effect produced by the heterogeneous interface structure formed by CoFe-LDH and MOFs.
[0052] Figure 6 The electrode materials prepared in the above-mentioned Examples 1, 2 and 3 are at 2 mA / cm 2 The GCD curves under 2 mA / cm2 are shown. It is obvious that the GCD curves of all electrode materials have a clear charge-discharge platform, which further confirms that the capacitance contribution of these samples is mainly related to the redox reaction, which is consistent with the redox peak in the CV curve. It can be clearly seen from the figure that the discharge time of CoFe-LDH@MOFs-10h electrode is the longest. CoFe-LDH@MOFs-10h has a high discharge time at 2 mA / cm2. 2 Provides 11333.29mF / cm at a current density of 2 High specific capacitance.
[0053] Figure 7 The electrode materials prepared in the above-mentioned embodiments 1, 2 and 3 are in the range of 2 to 20 mA / cm 2 The area capacitance under different current densities is shown in Table 1.
[0054] Table 1
[0055]
[0056]
[0057] Based on these results, it is clear that through a ligand-assisted conversion strategy, CoFe-LDH can be in situ converted into a CoFe-LDH@MOFs composite with a 2D / 2D heterostructure. This unique structural design significantly improves the electrochemical performance of the material. Furthermore, the hydrothermal reaction time has a significant impact on the material's performance. By regulating the hydrothermal time, comparative electrode materials with different performances were prepared. As shown in Table 1, the electrode materials prepared at different hydrothermal times exhibit significant differences in electrochemical performance, indicating that the hydrothermal time is one of the key parameters affecting material performance.
[0058] Figure 8The CoFe-LDH@MOFs-10h in Example 1 was 2 The cycling stability diagram at a current density of Figure 8 It can be seen that after 5000 cycle tests, the capacitance retention rate can still reach 77.78%.
[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A method for preparing a CoFe-LDH@MOFs composite material, characterized in that: The following steps are involved: (1) adding nickel foam to deionized water containing a cobalt source, an iron source, urea, and ammonium fluoride, placing the mixture in an autoclave for hydrothermal reaction, and washing and drying to obtain CoFe-LDH grown on the nickel foam; (2) The nickel foam loaded with CoFe-LDH was added to an N,N-dimethylformamide solution containing terephthalic acid, placed in an autoclave for hydrothermal reaction, and washed and dried to obtain a CoFe-LDH@MOFs composite material.
2. The method for preparing a CoFe-LDH@MOFs composite material according to claim 1, wherein: In step (1), the molar volume ratio of the cobalt source, the iron source, urea, ammonium fluoride and deionized water is: (0.5-1.5) mmol: (0.25-0.75) mmol: (5-15) mmol: (2-6) mmol: 30 mL.
3. The method for preparing a CoFe-LDH@MOFs composite material according to claim 1, wherein: In step (1), the cobalt source is cobalt nitrate hexahydrate, and the iron source is ferric nitrate nonahydrate.
4. The method for preparing a CoFe-LDH@MOFs composite material according to claim 1, wherein: In step (1), the temperature of the hydrothermal reaction is 100-140° C., and the time of the hydrothermal reaction is 4-8 hours.
5. The method for preparing a CoFe-LDH@MOFs composite material according to claim 1, wherein: In step (1), the solvents used for washing are deionized water and anhydrous ethanol.
6. The method for preparing a CoFe-LDH@MOFs composite material according to claim 1, wherein: In step (2), the molar volume ratio of terephthalic acid and N,N-dimethylformamide solution is: (0.5-1.5) mmol:30 mL.
7. The method for preparing a CoFe-LDH@MOFs composite material according to claim 1, wherein: In step (2), the temperature of the hydrothermal reaction is 140 to 180° C., and the time of the hydrothermal reaction is 8 to 12 hours.
8. The method for preparing a CoFe-LDH@MOFs composite material according to claim 1, wherein: In step (2), the solvents used for washing are N,N-dimethylformamide and anhydrous ethanol.
9. A CoFe-LDH@MOFs composite material, characterized by: The CoFe-LDH@MOFs composite material is prepared by the preparation method according to any one of claims 1 to 8.
10. The use of a CoFe-LDH@MOFs composite material according to claim 9, characterized in that: The CoFe-LDH@MOFs composite material is used in the preparation of supercapacitors.