A moF material rich in coordination defects and preparation method and application thereof

Abstract

The application discloses a MOF material rich in coordination defects and a preparation method and application thereof. The preparation method of the MOF material rich in coordination defects comprises the following steps: 1) preparing a nickel cobalt layered double hydroxide loaded nickel foam; and 2) dissolving 2,6-naphthalene dicarboxylic acid and ferrocene formic acid in a mixed solvent composed of N,N-dimethylformamide and water, and then adding the nickel cobalt layered double hydroxide loaded nickel foam to perform a solvothermal reaction. The MOF material rich in coordination defects has excellent catalytic performance and good stability when used as an electrode material for water electrolysis hydrogen production, can effectively reduce the energy consumption of water electrolysis hydrogen production and improve the efficiency of water electrolysis hydrogen production, and is low in production cost, wide in raw material sources and simple in preparation method, and is suitable for large-scale industrial production and application.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis for hydrogen production, specifically to a MOF material rich in coordination defects, its preparation method, and its applications. Background Technology

[0002] Hydrogen energy is a secondary clean energy source with advantages such as being green and environmentally friendly, and having abundant raw material sources, making it a promising candidate for widespread application. Currently, industrial hydrogen production primarily relies on high-temperature methane cracking (where methane decomposes into carbon and hydrogen at high temperatures). This method is not only energy-intensive but also produces polluting gases such as carbon dioxide, severely limiting the application of hydrogen energy. Water electrolysis, on the other hand, is a method that generates hydrogen and oxygen through the electrolysis of water. This method can utilize renewable energy sources (first converting renewable energy into electricity, then using it for water electrolysis) and has a brighter future compared to high-temperature methane cracking.

[0003] The water electrolysis for hydrogen production (OWS) reaction comprises two half-reactions: the cathode hydrogen evolution reaction (HER) and the anode oxygen evolution reaction (OER). The OER reaction involves a four-electron transfer process (compared to the HER reaction which involves only a two-electron transfer), resulting in slow kinetics and being a key factor limiting the efficiency of water electrolysis. Therefore, a catalyst is needed to promote the oxygen evolution reaction. Currently, commonly used OER catalysts are mainly noble metal catalysts (e.g., platinum, iridium). These catalysts have high catalytic activity, but the scarcity and high cost of noble metals keep the cost of water electrolysis for hydrogen production high. MOF materials are materials with a periodic network structure assembled from a metal source and organic ligands, offering advantages such as abundant resources and low cost. During the OER reaction, MOF materials are converted into metal hydroxyl oxides, which, as the true active sites for the OER reaction, can promote it. Therefore, MOF materials hold promise as a replacement for noble metal catalysts. However, existing MOF materials exhibit low catalytic activity and poor stability, making it difficult to fully meet the requirements of practical applications.

[0004] Therefore, developing a MOF material with high catalytic activity and good stability is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a MOF material rich in coordination defects, its preparation method, and its application.

[0006] The technical solution adopted in this invention is:

[0007] A method for preparing a MOF material rich in coordination defects includes the following steps:

[0008] 1) Dissolve cobalt salt, nickel salt and quaternary ammonium salt cationic surfactants in a mixed solvent composed of low carbon alcohol and water, and then add nickel foam to carry out a solvothermal reaction to obtain nickel foam loaded with nickel-cobalt layered bimetallic hydroxide.

[0009] 2) Dissolve 2,6-naphthalenedicarboxylic acid and ferrocene carboxylic acid in a mixed solvent composed of N,N-dimethylformamide and water, and then add nickel foam loaded with nickel-cobalt layered bimetallic hydroxide for a solvothermal reaction to obtain MOF material rich in coordination defects.

[0010] Preferably, a method for preparing a MOF material rich in coordination defects includes the following steps:

[0011] 1) Dissolve cobalt salt, nickel salt and quaternary ammonium salt cationic surfactant in a mixed solvent composed of low carbon alcohol and water, then add nickel foam for solvothermal reaction, then wash the product with water and anhydrous ethanol, and then dry to obtain nickel foam loaded with nickel-cobalt layered bimetallic hydroxide.

[0012] 2) Dissolve 2,6-naphthalenedicarboxylic acid and ferrocene carboxylic acid in a mixed solvent composed of N,N-dimethylformamide and water, then add nickel foam loaded with nickel-cobalt layered bimetallic hydroxide for a solvothermal reaction, then wash the product with water and anhydrous ethanol, and then dry it to obtain MOF material rich in coordination defects.

[0013] Preferably, the cobalt salt in step 1) is at least one of cobalt nitrate, cobalt sulfate, cobalt chloride, and cobalt acetate.

[0014] Preferably, the nickel salt in step 1) is at least one of nickel nitrate, nickel sulfate, nickel chloride, and nickel acetate.

[0015] Preferably, the quaternary ammonium salt cationic surfactant in step 1) is at least one of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and octadecyltrimethylammonium bromide.

[0016] Preferably, the lower alcohol in step 1) is at least one of methanol, ethanol, and propanol.

[0017] Preferably, in step 1), the volume ratio of the low-carbon alcohol to water in the mixed solvent composed of low-carbon alcohol and water is 3 to 6:1.

[0018] Preferably, the molar ratio of the cobalt salt, nickel salt, and quaternary ammonium salt cationic surfactant in step 1) is 1:1 to 3:2 to 4.

[0019] Preferably, the mass ratio of cobalt salt to nickel foam in step 1) is 1:0.1 to 5.

[0020] Preferably, the solvothermal reaction in step 1) is carried out at a temperature of 140℃ to 200℃ for a reaction time of 5h to 15h.

[0021] Preferably, the molar ratio of 2,6-naphthalenedicarboxylic acid and ferrocene carboxylic acid in step 2) is 1:0.1 to 1.0.

[0022] Preferably, in step 2), the volume ratio of N,N-dimethylformamide to water in the mixed solvent composed of N,N-dimethylformamide and water is 1 to 2:1.

[0023] Preferably, the mass ratio of 2,6-naphthalenedicarboxylic acid and nickel foam loaded with nickel-cobalt layered bimetallic hydroxide in step 2) is 1:0.05 to 5.

[0024] Preferably, the solvothermal reaction in step 2) is carried out at a temperature of 100℃ to 150℃ for a reaction time of 10h to 20h.

[0025] A MOF material rich in coordination defects is prepared by the above-described method.

[0026] A catalyst for the oxygen evolution reaction in water electrolysis comprises the aforementioned MOF material rich in coordination defects.

[0027] Application of a MOF material rich in coordination defects as described above in hydrogen production by water electrolysis.

[0028] The beneficial effects of this invention are: the MOF material of this invention is rich in coordination defects, and its use as an electrode material for hydrogen production by water electrolysis has the advantages of excellent catalytic performance and good stability. It can effectively reduce the energy consumption of hydrogen production by water electrolysis and improve the efficiency of hydrogen production by water electrolysis. Moreover, its production cost is low, the raw material sources are wide, and the preparation method is simple, making it suitable for large-scale industrial production and application.

[0029] Specifically:

[0030] 1) The MOF material of the present invention is rich in coordination defects. The incorporation of defects makes the MOF material contain a large number of unsaturated metal sites. The unsaturated metal sites are more easily oxidized and can be converted into more metal hydroxy oxides, thereby significantly improving the OER activity of the MOF material.

[0031] 2) The MOF material of the present invention has excellent stability and can effectively resist volume expansion and structural damage. It can maintain structural and performance stability even after long-term use.

[0032] 3) The MOF material of the present invention has low production cost, wide availability of raw materials, and simple preparation method, making it suitable for large-scale industrial production and application. Attached Figure Description

[0033] Figure 1 The NiCo LDH / NF and NiCo NDC-Fc in Example 1 are examples of the NiCo LDH / NF and NiCo NDC-Fc in Example 1. 0.67 SEM images of / NF and NiCo NDC / NF in Comparative Example 1.

[0034] Figure 2 The NiCo NDC-Fc in Example 1 0.67 / NF's EDS graph.

[0035] Figure 3 The NiCo NDC-Fc in Example 1 0.67 / NF element distribution diagram.

[0036] Figure 4 The NiCo LDH / NF and NiCo NDC-Fc in Example 1 0.67 XRD pattern of / NF.

[0037] Figure 5 The NiCo NDC-Fc in Example 1 0.67 / NF, NiCo NDC / NF in Comparative Example 1, and NiCo NDC-Cc in Comparative Example 2 0.67 Fourier transform infrared spectrum of / NF.

[0038] Figure 6 The NiCo NDC-Fc in Example 1 0.67 Electron paramagnetic resonance spectra of / NF and NiCo NDC / NF in Comparative Example 1.

[0039] Figure 7 The NiCo NDC-Fc in Example 1 0.67 Nitrogen adsorption-desorption isotherms of / NF and NiCo NDC / NF in Comparative Example 1.

[0040] Figure 8 The NiCo NDC-Fc in Example 1 0.67 / NF, NiCo NDC-Fc1 / NF in Example 2, NiCo NDC-Fc in Example 3 0.43 / NF, NiCo NDC-Fc in Example 4 0.25 / NF, NiCo NDC-Fc in Example 5 0.11 / NF, NiCo NDC / NF in Comparative Example 1, and NiCo NDC-Cc in Comparative Example 2 0.67 LSV curve of / NF.

[0041] Figure 9 The NiCo NDC-Fc in Example 10.67 / NF, NiCo NDC-Fc1 / NF in Example 2, NiCo NDC-Fc in Example 3 0.43 / NF, NiCo NDC-Fc in Example 4 0.25 / NF, NiCo NDC-Fc in Example 5 0.11 / NF, NiCo NDC / NF in Comparative Example 1, and NiCo NDC-Cc in Comparative Example 2 0.67 Overpotential diagram of / NF.

[0042] Figure 10 The NiCo NDC-Fc in Example 1 0.67 / NF, NiCo NDC-Fc1 / NF in Example 2, NiCo NDC-Fc in Example 3 0.43 / NF, NiCo NDC-Fc in Example 4 0.25 / NF, NiCo NDC-Fc in Example 5 0.11 / NF, NiCo NDC / NF in Comparative Example 1, and NiCo NDC-Cc in Comparative Example 2 0.67 Tafel slope plot of / NF.

[0043] Figure 11 The NiCo NDC-Fc in Example 1 0.67 / NF, NiCo NDC-Fc1 / NF in Example 2, NiCo NDC-Fc in Example 3 0.43 / NF, NiCo NDC-Fc in Example 4 0.25 / NF, NiCo NDC-Fc in Example 5 0.11 / NF, NiCo NDC / NF in Comparative Example 1, and NiCo NDC-Cc in Comparative Example 2 0.67 Double-layer capacitance diagram of / NF.

[0044] Figure 12 The NiCo NDC-Fc in Example 1 0.67 / NF, NiCo NDC-Fc1 / NF in Example 2, NiCo NDC-Fc in Example 3 0.43 / NF, NiCo NDC-Fc in Example 4 0.25 / NF, NiCo NDC-Fc in Example 5 0.11 / NF, NiCo NDC / NF in Comparative Example 1, and NiCo NDC-Cc in Comparative Example 2 0.67 Electrochemical impedance spectroscopy of / NF.

[0045] Figure 13 The NiCo NDC-Fc in Example 1 0.67 The constant voltage stability test results of / NF are shown in the figure.

[0046] Figure 14 The NiCo NDC-Fc in Example 1 0.67 CV curve of / NF.

[0047] Figure 15 The CV curves for NiCo NDC / NF in Comparative Example 1 are shown.

[0048] Figure 16 The NiCo NDC-Fc in Example 1 0.67 Comparison of metal redox peaks of / NF and NiCo NDC / NF in Comparative Example 1. Detailed Implementation

[0049] The present invention will be further explained and described below with reference to specific embodiments.

[0050] Example 1:

[0051] A MOF material rich in coordination defects is prepared by the following method:

[0052] 1) Dissolve 348 mg (1.2 mmol) of Co(NO3)2·6H2O, 524 mg (1.8 mmol) of Ni(NO3)2·6H2O, and 1 g (2.7 mmol) of hexadecyltrimethylammonium bromide (CTAB) in a mixed solvent of methanol and deionized water (60 mL of anhydrous methanol and 12 mL of deionized water) to form a homogeneous solution. Pour the solution into a high-pressure reactor, and then add 0.126 g of nickel foam (large). The small size is 1.5cm×3cm×1mm; the nickel foam was pretreated as follows: the nickel foam was ultrasonically cleaned for 20min each with 2.0mol / L hydrochloric acid, deionized water and anhydrous ethanol, and then dried in a vacuum drying oven at 60℃. It was reacted at 180℃ for 6h and then naturally cooled to room temperature. The product was then taken out and washed with water and anhydrous ethanol multiple times. It was then dried in a vacuum drying oven at 60℃ overnight to obtain nickel foam loaded with nickel-cobalt layered bimetallic hydroxide (denoted as NiCo LDH / NF).

[0053] 2) 130 mg (0.6 mmol) of 2,6-naphthalenedicarboxylic acid and 92 mg (0.4 mmol) of ferrocene carboxylic acid were dissolved in a mixed solvent of N,N-dimethylformamide and deionized water (32 mL of N,N-dimethylformamide and 16 mL of deionized water) to form a homogeneous solution. The solution was then injected into a high-pressure reactor, and 0.1 g of nickel foam loaded with nickel-cobalt layered bimetallic hydroxide was added. The reaction was carried out at 130 °C for 12 h, and then naturally cooled to room temperature. The product was then removed and washed repeatedly with water and anhydrous ethanol, and then dried overnight at 60 °C in a vacuum drying oven to obtain the MOF material rich in coordination defects (denoted as NiCo NDC-Fc). 0.67 / NF).

[0054] Comparative Example 1:

[0055] A MOF material (denoted as NiCo NDC / NF) is identical to that in Example 1, except that the amount of 2,6-naphthalenedicarboxylic acid in step 2) is adjusted from "0.6 mmol" to "1 mmol" and the amount of ferrocene carboxylic acid in step 2) is adjusted from "0.4 mmol" to "0".

[0056] Comparative Example 2:

[0057] A MOF material (denoted as NiCo NDC-Cc) 0.67 The preparation method is identical to Example 1, except that ferrocene carboxylic acid in step 2) is replaced with an equimolar amount of 1-cyclopentenic acid.

[0058] Performance testing:

[0059] 1) Nickel foam (NiCo LDH / NF) loaded with nickel-cobalt layered bimetallic hydroxide in Example 1, and MOF material rich in coordination defects (NiCo NDC-Fc) in Example 1. 0.67 Scanning electron microscope (SEM) images of the MOF material (NiCo NDC / NF) and Comparative Example 1 (NiCo NDC / NF) are shown below. Figure 1 As shown.

[0060] Depend on Figure 1 It can be seen that NiCo LDH / NF exhibits a nanosheet morphology, which is then further converted in situ into NiCo NDC-Fc. 0.67 / NF, the morphology of the nanosheets is maintained.

[0061] 2) MOF material rich in coordination defects (NiCo NDC-Fc) in Example 1 0.67 The EDS graph of / NF is as follows Figure 2 As shown, the element distribution map is as follows: Figure 3 As shown.

[0062] Depend on Figure 2 and Figure 3 It can be seen that: NiCo NDC-Fc 0.67 / NF contains C, O, Fe, Co, and Ni elements; the incorporation of the defective ligand (ferrocene carboxylic acid) introduces Fe element; NiCo NDC-Fc 0.67 / NF is a nickel foam substrate with a high Ni content (39.48 wt%), while the contents of C, O, Fe, and Co are 33.30 wt%, 8.12 wt%, 5.30 wt%, and 13.8 wt%, respectively. Surface scanning of the material after region selection showed that C, O, Fe, Co, and Ni are uniformly distributed in NiCoNDC-Fc. 0.67 / NF surface.

[0063] 3) The nickel foam (NiCo LDH / NF) loaded with nickel-cobalt layered bimetallic hydroxide and the MOF material (NiCo NDC-Fc) rich in coordination defects in Example 1 0.67 The X-ray diffraction (XRD) pattern of / NF is shown below. Figure 4 As shown.

[0064] Depend on Figure 4 It can be seen that: NiCo NDC-Fc 0.67 The peak positions of / NF (around 7° and 14.18°) correspond to those of MOF materials synthesized using 2,6-naphthalenedicarboxylic acid as a ligand, indicating the successful realization of the NiCo LDH / NF to NiCo NDC-Fc synthesis. 0.67 / NF conversion.

[0065] 4) MOF material rich in coordination defects (NiCo NDC-Fc) in Example 1 0.67 / NF), MOF material in Comparative Example 1 (NiCo NDC / NF) and MOF material in Comparative Example 2 (NiCo NDC-Cc) 0.67 The Fourier transform infrared spectrum of / NF is as follows: Figure 5 As shown.

[0066] Depend on Figure 5 It can be seen that when NiCo LDH / NF is converted in situ to NiCo NDC-Fc... 0.67 After / NF, the absorption peaks of C=O and CO stretching vibrations of the carboxyl group in the free ligand disappear after MOF formation, indicating that the carboxyl group in the ligand has coordinated with the metal ion.

[0067] 5) MOF material rich in coordination defects (NiCo NDC-Fc) in Example 1 0.67The electron paramagnetic resonance spectra of the MOF material (NiCo NDC / NF) and the MOF material (NiCo NDC / NF) in Comparative Example 1 are shown below. Figure 6 As shown.

[0068] Depend on Figure 6 It can be seen that: NiCo NDC-Fc 0.67 / NF exhibits a distinct characteristic signal at g = 2.23, which is enhanced and broadened, indicating that the incorporation of ferrocene-formic acid generates a large number of unpaired electrons in the MOF material.

[0069] 6) MOF material rich in coordination defects (NiCo NDC-Fc) in Example 1 0.67 The nitrogen adsorption-desorption isotherms of the MOF material (NiCo NDC / NF) and the MOF material (NiCo NDC / NF) in Comparative Example 1 are shown below. Figure 7 As shown.

[0070] Depend on Figure 7 It can be seen that: NiCo NDC-Fc 0.67 The nitrogen adsorption-desorption isotherms of both / NF and NiCo NDC / NF exhibit type I+IV characteristics, indicating the presence of micropores and mesopores in the materials. Furthermore, the NiCo NDC-Fc doped with ferrocene formic acid also shows this characteristic. 0.67 The adsorption capacity of / NF increases, and the surface area increases.

[0071] Example 2:

[0072] A MOF material rich in coordination defects (denoted as NiCo NDC-Fc1 / NF) is identical to that in Example 1 except that the amount of 2,6-naphthalenedicarboxylic acid in step 2) is adjusted from "0.6 mmol" to "0.5 mmol" and the amount of ferrocene carboxylic acid in step 2) is adjusted from "0.4 mmol" to "0.5 mmol".

[0073] Example 3:

[0074] A MOF material rich in coordination defects (denoted as NiCo NDC-Fc) 0.43 The method is identical to Example 1 except that the amount of 2,6-naphthalenedicarboxylic acid in step 2) is adjusted from "0.6 mmol" to "0.7 mmol" and the amount of ferrocene carboxylic acid in step 2) is adjusted from "0.4 mmol" to "0.3 mmol".

[0075] Example 4:

[0076] A MOF material rich in coordination defects (denoted as NiCo NDC-Fc) 0.25The method is identical to Example 1 except that the amount of 2,6-naphthalenedicarboxylic acid in step 2) is adjusted from "0.6 mmol" to "0.8 mmol" and the amount of ferrocene carboxylic acid in step 2) is adjusted from "0.4 mmol" to "0.2 mmol".

[0077] Example 5:

[0078] A MOF material rich in coordination defects (denoted as NiCo NDC-Fc) 0.11 The method is identical to Example 1 except that the amount of 2,6-naphthalenedicarboxylic acid in step 2) is adjusted from "0.6 mmol" to "0.9 mmol" and the amount of ferrocene carboxylic acid in step 2) is adjusted from "0.4 mmol" to "0.1 mmol".

[0079] Electrochemical performance testing:

[0080] 1) The MOF material (NiCo NDC-Fc) rich in coordination defects from Examples 1-5 0.67 / NF, NiCo NDC-Fc1 / NF, NiCo NDC-Fc 0.43 / NF、NiCo NDC-Fc 0.25 / NF and NiCo NDC-Fc 0.11 / NF, collectively referred to as NiCo NDC-Fc x / NF), MOF material in Comparative Example 1 (NiCo NDC / NF) and MOF material in Comparative Example 2 (NiCo NDC-Cc) 0.67 A three-electrode system was assembled using an Hg / HgO electrode as the working electrode, a carbon rod as the counter electrode, an Hg / HgO electrode as the reference electrode, and a 1.0 mol / L KOH aqueous solution as the electrolyte. Electrochemical tests were then performed, and the resulting LSV curve is shown below. Figure 8 As shown, the overpotential diagram is as follows: Figure 9 As shown, the Tafel slope plot is as follows: Figure 10 As shown, the double-layer capacitance diagram is as follows: Figure 11 As shown, the electrochemical impedance spectroscopy diagram is as follows: Figure 12 As shown.

[0081] Depend on Figure 8 and Figure 9 It can be seen that: NiCo NDC-Fc 0.67 The onset potential of / NF is 1.32V, and it has the lowest overpotential at any current density after the OER reaction occurs; 10mA·cm -2 At that time, NiCo NDC-Fc 0.67 The overpotential of / NF is 220mV, even at 100mA·cm-2 Under high current density, NiCo NDC-Fc 0.67 The overpotential of / NF is only 250mV; NiCo NDC-Fc x The catalytic activity of / NF is significantly higher than that of NiCo NDC / NF; NiCo NDC-Cc 0.67 / NF introduces the defective ligand 1-cyclopentenic acid (Cc), which does not contain Fe element compared with ferrocene ligand. Therefore, by comparing the performance of Fe-defect-free MOF materials and defect-free MOF materials, the Fe-defect-free MOF materials have a smaller overpotential, indicating that the introduction of defects can effectively improve the activity of MOF materials, and the oxygen evolution performance of the materials after introducing Fe-defective ligands is better.

[0082] Depend on Figure 10 It can be seen that: NiCo NDC-Fc 0.67 The slope of the Tafel curve for / NF is 37 mV·dec. -1 The value is much smaller than other materials, indicating that NiCo NDC-Fc 0.67 / NF has faster kinetics and the best catalytic activity for the oxygen evolution reaction (the smaller the Tafel slope, the smaller the change in overpotential with the increase of current density, and the better the electrocatalytic performance).

[0083] Depend on Figure 11 It can be seen that: NiCo NDC-Fc 0.67 / NF has the largest active surface area, exposing more active sites, which means there are more active sites that can participate in the oxygen evolution reaction, making it more conducive to promoting reconstruction in the material and improving oxygen evolution performance.

[0084] Depend on Figure 12 It can be seen that: NiCo NDC-Fc 0.67 / NF has the smallest diameter semicircle, therefore its charge transport resistance is the lowest, resulting in the strongest charge transport capability and better oxygen evolution reaction activity compared to other materials. (Electrochemical impedance spectroscopy uses a small-amplitude AC signal to perturb the electrode and observes how the system follows the perturbation at steady state. A typical impedance spectrum at high frequencies is a semicircle, and the diameter of the semicircle represents the charge transport resistance R at the electrode-solution interface.) ct The smaller the diameter, the more R ct The smaller the value, the stronger the charge transport capacity and the better the catalytic performance of the catalyst.

[0085] 2) The MOF material (NiCo NDC-Fc) rich in coordination defects from Example 1 0.67A three-electrode system was assembled using an Hg / HgO electrode as the working electrode, a carbon rod as the counter electrode, an Hg / HgO electrode as the reference electrode, and a 1.0 mol / L KOH aqueous solution as the electrolyte. Stability testing was then performed using the chronoamperometry method. The constant voltage stability test results are shown in the figure below. Figure 13 As shown.

[0086] Depend on Figure 13 It can be seen that: NiCo NDC-Fc 0.67 / NF at a current density of 60 mA·cm -2 After a long-term test of 100 hours at the corresponding voltage, the current density hardly changed, indicating that NiCo NDC-Fc 0.67 / NF exhibits excellent stability and is suitable for industrial applications.

[0087] 3) The MOF material (NiCo NDC-Fc) rich in coordination defects from Example 1 0.67 A three-electrode system was assembled using NiCo NDC / NF and the MOF material (NiCo NDC / NF) from Comparative Example 1 as the working electrode, a carbon rod as the counter electrode, an Hg / HgO electrode as the reference electrode, and a 1.0 mol / L KOH aqueous solution as the electrolyte. Electrochemical cyclic voltammetry was then performed to obtain the NiCo NDC-NF electrode. 0.67 The CV curve of / NF is as follows Figure 14 As shown, the CV curve of NiCo NDC / NF is as follows. Figure 15 As shown, NiCo NDC-Fc 0.67 The comparison of metal redox peaks of / NF and NiCo NDC / NF is shown in the figure below. Figure 16 As shown.

[0088] Depend on Figures 14-16 It can be seen that by increasing the number of scans in the CV curve of the material, NiCo NDC-Fc was found to be... 0.67 The significantly increased redox peak area of ​​ / NF indicates that more metal sites in the material are oxidized, and that defective NiCo NDC-Fc is incorporated. 0.67 The redox peak area of ​​ / NF is significantly larger than that of NiCo NDC / NF, indicating that NiCo NDC-Fc 0.67 / NF contains more unsaturated metal sites, and further comparison of the CV plots before and after defect doping shows that the oxidation peak of the metal from valence II to valence III shifts negatively after defect doping, indicating that NiCo NDC-Fc 0.67 Unsaturated metal sites in / NF are more easily oxidized.

[0089] In summary, this invention transforms NiCo LDH / NF into NiCo NDC-Fc rich in coordination defects. x / NF, and the ratio of the major ligand (2,6-naphthalenedicarboxylic acid) to the defective ligand (ferroceneic acid) was adjusted to modify NiCo NDC-Fc. x By analyzing the defect content and performance of / NF, a catalyst for the oxygen evolution reaction in water electrolysis with excellent catalytic performance and good stability was finally obtained.

[0090] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing MOF materials rich in coordination defects, characterized in that, Includes the following steps: 1) Dissolve cobalt salt, nickel salt and quaternary ammonium salt cationic surfactants in a mixed solvent composed of low carbon alcohol and water, and then add nickel foam to carry out a solvothermal reaction to obtain nickel foam loaded with nickel-cobalt layered bimetallic hydroxide. 2) Dissolve 2,6-naphthalenedicarboxylic acid and ferrocene carboxylic acid in a mixed solvent composed of N,N-dimethylformamide and water, and then add nickel foam loaded with nickel-cobalt layered bimetallic hydroxide for a solvothermal reaction to obtain MOF material rich in coordination defects. Step 1) The molar ratio of the cobalt salt and nickel salt is 1:1 to 3; In step 2), the molar ratio of 2,6-naphthalenedicarboxylic acid and ferrocene carboxylic acid is 1:0.1 to 1. In step 2), the mass ratio of 2,6-naphthalenedicarboxylic acid to nickel foam loaded with nickel-cobalt layered bimetallic hydroxide is 1:0.05 to 5.

2. The preparation method according to claim 1, characterized in that: Step 1) The cobalt salt is at least one of cobalt nitrate, cobalt sulfate, cobalt chloride, and cobalt acetate; Step 1) The nickel salt is at least one of nickel nitrate, nickel sulfate, nickel chloride, and nickel acetate; Step 1) The quaternary ammonium salt cationic surfactant is at least one of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and octadecyltrimethylammonium bromide; Step 1) The lower alcohol is at least one of methanol, ethanol, and propanol.

3. The preparation method according to claim 1 or 2, characterized in that: Step 1) The molar ratio of the cobalt salt and the quaternary ammonium salt cationic surfactant is 1:2 to 4.

4. The preparation method according to claim 1 or 2, characterized in that: Step 1) The solvothermal reaction is carried out at a temperature of 140℃~200℃ for a reaction time of 5h~15h.

5. The preparation method according to claim 1, characterized in that: Step 2) The solvothermal reaction is carried out at a temperature of 100℃~150℃ for a reaction time of 10h~20h.

6. The preparation method according to claim 1 or 2, characterized in that: In step 1), the mass ratio of cobalt salt to nickel foam is 1:0.1 to 5; in step 1), the volume ratio of low-carbon alcohol to water in the mixed solvent composed of low-carbon alcohol and water is 3 to 6:1; in step 2), the volume ratio of N,N-dimethylformamide to water in the mixed solvent composed of N,N-dimethylformamide and water is 1 to 2:

1.

7. A MOF material rich in coordination defects, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 6.

8. A catalyst for the oxygen evolution reaction in water electrolysis, characterized in that, The MOF material containing coordination defects as described in claim 7.

9. The application of a MOF material rich in coordination defects as described in claim 7 in hydrogen production by water electrolysis.

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