Mof-derived nitrogen cobalt hetero-nanoscale box electrocatalyst, preparation method and application

Abstract

The application discloses an MOF-derived nitrogen cobalt hetero-nano box electrocatalyst, a preparation method and application, and the method steps for preparing the catalyst are as follows: S1: preparation of a ZIF-67 template; S2: dissolving the ZIF-67 template in S1 in anhydrous methanol, ultrasonic stirring and dissolving, and recording as solution A; S3: dissolving 1H-1,2,3-triazole in an anhydrous methanol solution and recording as solution B; S4: adding the solution B in S3 into the solution A in S2, stirring, and then standing to perform a substitution reaction; and S5: centrifuging, drying and carbonizing the product after the reaction in S4 under nitrogen protection to obtain the MOF-derived nitrogen cobalt hetero-nano box electrocatalyst. The 2-methyl imidazole in the imidazole zeolite framework ZIF-67 is partially substituted by a high-energy nitrogen-containing ligand 1H-1,2,3-triazole ligand, a rich nitrogen source is provided, and the coordination environment of cobalt atoms is locally constrained, so that the prepared electrocatalyst has a lower hydrogen evolution overpotential under the alkaline condition of 1 mol / L KOH aqueous solution.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to MOF-derived nitrogen-cobalt heterogeneous nanocrystal electrocatalysts, their preparation methods, and applications. Background Technology

[0002] With the rapid development of human society, fossil fuels such as oil, natural gas, and coal have been consumed in large quantities for industrial upgrading, leading to increasingly serious air pollution and energy resource depletion. Therefore, the demand for clean energy is growing daily, making the search for alternative clean energy sources urgent. To protect the environment and reduce human use of fossil fuels, researchers are focusing their efforts on exploring and developing more sustainable and renewable technologies for collecting, converting, and storing energy. Currently, significant progress has been made in research on new energy sources such as wind, solar, hydropower, and tidal energy. In particular, electrochemical hydrogen production technology has maintained a high growth rate in recent years and is considered a clean, sustainable, and green energy utilization method, with hydrogen as an energy conversion and storage medium receiving considerable attention. Therefore, against this backdrop, designing and developing low-cost, recyclable, environmentally friendly, highly stable, and low electrocatalytic hydrogen evolution overpotential non-precious metal catalysts has become a hot research topic.

[0003] Traditional precious metal electrocatalysts for hydrogen evolution reaction (HER), such as platinum- and ruthenium-containing catalysts, while requiring low overpotentials, exhibit limited catalytic activity and poor stability, making them unsuitable for long-term use. Furthermore, their preparation processes are complex, sometimes requiring high-temperature and high-pressure environments, resulting in significant energy consumption. On the other hand, precious metal electrocatalysts are susceptible to poisoning during use, leading to low metal site utilization efficiency and affecting catalytic performance, thus increasing precious metal consumption. Developing a non-precious metal electrocatalyst with good catalytic stability is a pressing technical problem in this field. Therefore, this invention effectively overcomes energy consumption by using non-precious metal cobalt as the metal source, and the synthesized electrocatalyst exhibits good stability during the electrocatalytic water splitting HER reaction, demonstrating potential for practical application. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, this invention proposes a MOF-derived nitrogen-cobalt heterogeneous nanocrystal electrocatalyst, its preparation method and application. By partially substituting the 2-methylimidazole in the imidazole zeolite framework ZIF-67 with the high-energy nitrogen-containing ligand 1H-1,2,3-triazole ligand, an abundant nitrogen source is provided and the coordination environment of cobalt atoms is locally constrained, so that the prepared electrocatalyst has a low hydrogen evolution overpotential.

[0005] The present invention proposes a MOF-derived nitrogen-cobalt heterogeneous nanocrystal electrocatalyst, which is formed by partial substitution of a zeolite imidazole framework with ligands and pyrolysis into a nitrogen-rich cobalt heterogeneous nanocube porous composite material with multiple Co / CoN heterogeneous catalytic centers.

[0006] The preparation method of the above-mentioned MOF-derived nitrogen-cobalt heterocell electrocatalyst proposed in this invention comprises the following steps:

[0007] S1: Preparation of ZIF-67 template;

[0008] S2: Mix a methanol solution of 1H-1,2,3-triazole with a methanol solution of the ZIF-67 template of S1 and react them.

[0009] S3: After the reaction, the product was centrifuged and dried, and then carbonized under nitrogen protection to obtain MOF-derived nitrogen-cobalt heterogeneous nanocrystal electrocatalyst.

[0010] Preferably, the method for preparing the ZIF-67 template includes the following steps:

[0011] S11: Dissolve 2-methylimidazole in deionized water;

[0012] S12: Cobalt nitrate hexahydrate and hexadecyl ammonium bromide are dissolved in deionized water and then added to the solution of S11 to carry out the reaction. After the reaction, the mixture is centrifuged, washed and dried to obtain the ZIF-67 template.

[0013] Preferably, the mass ratio of 2-methylimidazole, cobalt nitrate hexahydrate and hexadecylammonium bromide is 1:0.06-0.08:0.001-0.0015.

[0014] Preferably, the reaction conditions in S12 are: reaction temperature 20-25℃, stirring for 20-40 minutes first, and then standing for 1-2 hours.

[0015] Preferably, the centrifugation conditions in S12 are: rotation speed 8000-9500 r / min and time 5-7 min.

[0016] Preferably, the drying conditions in S12 are: temperature 50-70℃ and time 8-24h.

[0017] Preferably, the centrifugation conditions in S12 are: rotation speed 8000-9500 r / min, time 5-7 min; drying conditions are: temperature 50-70℃, time 8-24 h.

[0018] Preferably, the mass ratio of the ZIF-67 template to 1H-1,2,3-triazole is 1:0.5-1.5.

[0019] Preferably, the reaction conditions in S2 are: temperature 30-35℃ and time 15-25min.

[0020] Preferably, the centrifugation conditions in S3 are: rotation speed 8000-9500 r / min and time 5-7 min.

[0021] Preferably, the drying conditions in S3 are: temperature 50-70℃ and time 8-24h.

[0022] Preferably, the carbonization conditions in S3 are: temperature 400-600℃, time 1-3h, and heating rate 3-5℃ / min.

[0023] The present invention relates to the application of the MOF-derived nitrogen-cobalt heterogeneous nanocrystal electrocatalyst in the electrocatalytic water splitting for hydrogen production.

[0024] Mechanism of action

[0025] This invention employs a nitrogen-rich organic ligand exchange strategy, using nitrogen-rich organic ligands for local confinement, followed by high-temperature pyrolysis under a nitrogen atmosphere to transform the cobalt-containing composite into a cobalt heterogeneous electrocatalytic nanobox with abundant Co / CoN heteroparticle active sites and a porous structure. The composite material prepared by this method exhibits a hollow cubic morphology, high specific surface area, and abundant Co / CoN heterogeneous active sites, thereby optimizing the electrocatalytic hydrogen evolution reaction kinetics and gas-liquid mass transfer rate.

[0026] Beneficial technical effects

[0027] (1) In this invention, the 2-methylimidazole in the imidazole zeolite framework ZIF-67 is partially substituted by the high-energy nitrogen-containing ligand 1H-1,2,3-triazole ligand, providing an abundant nitrogen source and locally confining the coordination environment of cobalt atoms. Subsequent pyrolysis yields a cobalt heteroporous composite nanobox with multiple Co / CoN heterogeneous catalytic centers. During pyrolysis, the 1H-1,2,3-triazole high-energy nitrogen-containing ligand, due to the instability of the nitrogen-nitrogen double bond, easily decomposes at high temperatures, releasing energy instantaneously. This locally regulates the catalytic center of the catalyst, generating suitable pore structures and abundant catalytic active sites, while maintaining a good overall morphology before and after pyrolysis.

[0028] (2) The cobalt heteroporous composite material with rich Co / CoN heterocatalytic center prepared by the present invention can be used as a catalyst for hydrogen evolution reaction in electrocatalytic water splitting to produce hydrogen, and has a low hydrogen evolution overpotential under alkaline conditions of 1 mol / L KOH aqueous solution.

[0029] (3) The catalyst prepared by the present invention can regulate the pore structure and specific surface area of ​​the material by the substitution time of nitrogen-rich organic ligands; the preparation process is simple, easy to operate and reproduce, and convenient for industrial production. Attached Figure Description

[0030] Figure 1 The images are scanning electron micrographs (SEM) of the present invention; (a): ZIF-67 before calcination, (b): ZIF-67 after calcination, (c): Co / CoN-20 before calcination, (d): Co / CoN-20 after calcination;

[0031] Figure 2 In the diagram, (ab) is a transmission electron micrograph (TEM) of Co / CoN-20, (c) is a high-resolution electron micrograph (HRTEM) of Co / CoN-20, and (d) is a region electron diffraction (SAED) pattern of Co / CoN-20.

[0032] Figure 3 (a) shows the Fourier transform infrared (IR) images of Co / CoN-20 and ZIF-67 compared; (b) shows the X-ray diffraction (XRD) images of Co / CoN-20 and ZIF-67 compared.

[0033] Figure 4 (a) is the X-ray photoelectron spectroscopy (XPS) diagram of nitrogen species in Co / CoN-20, and (b) is a comparison diagram of the content distribution of different nitrogen species in Co / Co-20 and ZIF-67-NC.

[0034] Figure 5 The following are the polarization curves of the hydrogen evolution reaction of Co / CoN-20 in 1 mol / L KOH aqueous solution: (a) the Tafel slope, (b) the galvanostatic stability test curve of the hydrogen evolution reaction, and (d) the impedance curve.

[0035] Figure 6 The following are schematic diagrams of hydrogen production by water electrolysis for Co / CoN-20: (a) water decomposition curve, (b) water decomposition stability test curve, and (d) scanning electron micrograph (SEM) image after water decomposition stability test. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to specific embodiments.

[0037] In the embodiments of this invention, nitric acid hexahydrate, 1H-1,2,3-triazole and 2-methylimidazole were purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; potassium hydroxide was purchased from Sinopharm Chemical Reagent Co., Ltd.; and anhydrous methanol was purchased from Jiangsu Qiangsheng Functional Chemical Co., Ltd.; all the above raw materials were of analytical grade.

[0038] The ultrasonic cleaner used in this invention was purchased from Kunshan Ultrasonic Instrument Co., Ltd.; the scanning electron microscope (SEM, FlexSEM1000) was purchased from Hitachi, Japan; the transmission electron microscope (TEM, JEM2100F) was purchased from NEC Japan; the Fourier transform infrared spectrometer (FT-IR, Nicolet is50) was purchased from Thermo Fisher Scientific, USA; the X-ray photoelectron spectrometer (XPS, 250xi) was purchased from Thermo Fisher Scientific; the X-ray diffractometer (XRD, Smartlab SE) was purchased from Rigaku, Japan; and the electrochemical workstation was purchased from Shanghai Chenhua Instrument Co., Ltd.

[0039] Example 1

[0040] The method for preparing MOF-derived cobalt-nitrogen heterocell electrocatalysts proposed in this invention comprises the following steps:

[0041] S1: Weigh 4.54g of 2-methylimidazole and place it in a beaker. Then measure 70mL of deionized water into the beaker and sonicate to dissolve it to form a homogeneous and clear solution.

[0042] S2: Weigh 0.29g of Co(NO3)2·6H2O and 5mg of hexadecylammonium bromide and place them in a beaker. Then measure 10mL of deionized water into the beaker and sonicate to dissolve it to form a homogeneous and clear solution.

[0043] S3: Add the solution of S2 dropwise to the solution of S1 at room temperature, while stirring the solution of S1 continuously for 30 minutes to ensure that the materials are mixed evenly, and then let it stand for 2 hours.

[0044] S4: Centrifuge the product after standing in S3 at 8500 r / min for 5 min, and then dry the solid material at 50℃ for 24 h. The dried sample is recorded as ZIF-67.

[0045] S5: The dried material from S4 is heated to 500℃ at a rate of 5℃ / min and calcined for 2 hours to obtain the composite material ZIF-67-NC.

[0046] Example 2

[0047] The method for preparing MOF-derived cobalt-nitrogen heterocell electrocatalysts proposed in this invention comprises the following steps:

[0048] S1: Weigh 500 mg of ZIF-67 template and place it in a beaker. Then measure 50 mL of anhydrous methanol solution into the beaker and ultrasonically stir until a purple solution is formed.

[0049] S2: Measure 600 μL of 1H-1,2,3-triazole into a beaker, then measure 50 mL of anhydrous methanol solution into the beaker, and sonicate to form a homogeneous and clear solution.

[0050] S3: Add the solution of S2 dropwise to the solution of S2 at room temperature while stirring. After the addition is complete, stir for 3 minutes to mix the materials evenly. Then control the reaction temperature at 30°C and let it stand for 20 minutes.

[0051] S4: Centrifuge the product after standing in S3 at 8000 r / min for 3 min, and then dry the solid material after centrifugation at 50℃ for 12 h.

[0052] S5: The dried material from S4 is heated to 500℃ at a rate of 5℃ / min and calcined for 2 hours to obtain the composite material Co / CoN-NC-20.

[0053] Example 3

[0054] The method for preparing MOF-derived cobalt-nitrogen heterocell electrocatalysts proposed in this invention comprises the following steps:

[0055] S1: Weigh 500 mg of ZIF-67 template and place it in a beaker. Then measure 50 mL of anhydrous methanol solution into the beaker and ultrasonically stir until a purple solution is formed.

[0056] S2: Measure 600 μL of 1H-1,2,3-triazole into a beaker, then measure 50 mL of anhydrous methanol solution into the beaker, and sonicate to form a homogeneous and clear solution.

[0057] S3: Add the solution of S2 dropwise to the solution of S2 at room temperature while stirring. After the addition is complete, stir for 3 minutes to mix the materials evenly. Then control the reaction temperature at 30°C and let it stand for 40 minutes.

[0058] S4: Centrifuge the product after standing in S3 at 8000 r / min for 3 min, and then dry the solid material after centrifugation at 50℃ for 12 h.

[0059] S5: The dried material from S4 is heated to 500℃ at a rate of 5℃ / min and calcined for 2 hours to obtain the composite material Co / CoN-NC-40.

[0060] Example 4

[0061] The method for preparing MOF-derived cobalt-nitrogen heterocell electrocatalysts proposed in this invention comprises the following steps:

[0062] S1: Weigh 500 mg of ZIF-67 template and place it in a beaker. Then measure 50 mL of anhydrous methanol solution into the beaker and ultrasonically stir until a purple solution is formed.

[0063] S2: Measure 600 μL of 1H-1,2,3-triazole into a beaker, then measure 50 mL of anhydrous methanol solution into the beaker, and sonicate to form a homogeneous and clear solution.

[0064] S3: Add the solution of S2 dropwise to the solution of S1 at room temperature while stirring. After the addition is complete, stir for 3 minutes to mix the materials evenly. Then control the reaction temperature at 30°C and let it stand for 90 minutes.

[0065] S4: Centrifuge the product after standing in S3 at 8000 r / min for 3 min, and then dry the solid material after centrifugation at 50℃ for 12 h.

[0066] S5: The dried material from S4 is heated to 500℃ at a rate of 5℃ / min and calcined for 2 hours to obtain the composite material Co / CoN-NC-90.

[0067] Depend on Figure 1 It can be seen that when no 1H-1,2,3-triazole organic ligand is added for substitution, the ZIF-67 template sample exhibits a cubic morphology and a small size, such as... Figure 1 As shown in (a); after high-temperature carbonization, surface shrinkage can be observed, with each surface centrally concave, as... Figure 1 As shown in (b); when 1H-1,2,3-triazole organic ligands were added for substitution, the samples exhibited similar cubic morphologies with little change in size, such as Figure 1 As shown in (c); furthermore, after high-temperature carbonization, it can be observed that the sample retains its intact cubic shape without damage, and the degree of surface wrinkling is relatively weaker than before replacement, but the surface becomes rougher, as shown in (c). Figure 1 As shown in (d).

[0068] Furthermore, the electrochemical performance of the sample was characterized using a three-electrode system on a CHI760D electrochemical workstation. 1.5 mg of the experimental sample was weighed and 15 μL of a 15 wt% polyvinylidene fluoride (PVDF) solution as a conductive binder was added. The conductive binder was prepared using N-methylpyrrolidone (NMP) as the solution. The sample and PVDF were added together to the NMP solution and sonicated for 30 minutes to dissolve the PVDF in the NMP, ensuring complete dispersion of the sample material in the solution. Next, the prepared suspension was dropwise onto a pre-prepared graphite sheet (1 cm × 1 cm) using a pipette, with a loading of 0.5 mg / cm². 2Next, the electrode with the sample applied was placed in an oven at 80°C and dried for 2 hours to prepare the working electrode. In the three-electrode system, the working electrode was a graphite sheet (1cm × 1cm) loaded with the test sample; the counter electrode was a graphite electrode; and the reference electrode was a mercury / mercury oxide (Hg / HgO) electrode. A 1 mol / L potassium hydroxide solution (pH = 13.8) was used as the electrolyte. All potentials used in this paper are derived from the Nernst equation, E. RHE =E Hg / HgO +0.098+0.0591*pH is converted to the corresponding value of the reversible hydrogen electrode (RHE), where E is the pH value. Hg / HgO This is the potential applied to the reference electrode, the Hg / HgO electrode. The hydrogen evolution performance of the catalyst material was tested using linear sweep voltammetry (LSV), and the long-term stability of the catalyst material was tested using chronopotentialography (CP).

[0069] For the partially substituted organic ligand ZIF-67 carbonized samples, the morphology and composition of the products were further discussed using transmission electron microscopy (TEM). TEM images showed that the pyrolytic sample Co / CoN-NC-20 retained its original cubic shape after heat treatment. The surface was densely packed with clustered particles, with internal cavities. This is attributed to the pyrolysis of 1H-1,2,3-triazole, a high-energy ligand whose rapid decomposition and heat release lead to a lack of carbonaceous separation between metal ions, making it easier to form nitrogen-rich clusters and cavities. Figure 2 As shown in (ab), high-resolution transmission electron microscopy (HRTEM) images reveal the presence of elemental cobalt (Co)(111) and cobalt nitride (CoN)(111) crystal planes within the Co / CoN-NC-20 nitrogen-rich clusters. The interplanar spacings are 0.1937 nm and 0.2431 nm, respectively. A Co / CoN heterostructure is formed at the interface between the two crystal planes, as shown in (ab). Figure 2 As shown in (c), distinct diffraction rings are observed in the selected area electron diffraction (SAED) image, further confirming the formation of elemental cobalt (Co) and cobalt nitride (CoN) species in the carbonized material, consistent with the results in the HETEM image. Figure 2 As shown in (d), this MOF-derived cubic nitrogen-rich material undergoes nitrogen-rich component aggregation during high-temperature heat treatment, thereby preparing a cobalt heterogeneous nanocatalyst with abundant Co / CoN heterogeneous active sites.

[0070] X-ray photoelectron spectroscopy (XPS) revealed that the Co-Nx content in Co / CoN-NC-20 reached 74%, significantly higher than the Co-Nx content (26%) of the ZIF-67 template before substitution with nitrogen-rich ligands. Figure 3As shown in (ab). Furthermore, Co-Nx is crucial for the formation of active Co / CoN heterocatalytic active sites and for liquid adsorption and gas evolution on the material surface, which is beneficial for enhancing the conductivity and gas-liquid diffusion transport rate of the electrocatalyst.

[0071] Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) spectra show that 1H-1,2,3-triazole successfully partially substituted the 2-methylimidazolium ligand in the ZIF-67 template. The FT-IR spectrum shows that at 750 cm⁻¹... -2 and 797cm -2 The peaks at 2915 cm⁻¹ belong to the stretching vibration peak of the C=N double bond in the 2-methylimidazole molecule and the antisymmetric stretching vibration peak of the N=N bond in the 1H-1,2,3-triazole molecule, respectively. -2 The peak at [location] belongs to the stretching vibration peak of the methyl group CH in the dimethylimidazole molecule, proving that there is partial 1H-1,2,3-triazole coordinated with the cobalt salt in Co / CoN-20, such as... Figure 4 As shown in Figure a, in the X-ray diffraction spectrum, after 20 minutes of partial substitution of the 1H-1,2,3-triazole organic ligand, the characteristic peaks belonging to ZIF-67 were weakened. This may be because the substitution of the 1H-1,2,3-triazole for the 2-methylimidazolium ligand in ZIF-67 disrupts the periodicity of the coordination between the cobalt salt and 2-methylimidazolium in ZIF-67, resulting in a decrease in crystallinity. Figure 4 As shown in b.

[0072] The HER performance of the product is as follows: The HER activity of the Co / CoN-NC-20 electrocatalyst in 1 mol / L KOH solution was studied using a Chenhua electrochemical workstation. Linear sweep voltammetry (LSV) results showed that Co / CoN-NC-20 achieved 10 mA / cm². 2 The required overpotential (η) for the current density is only 115mV, such as Figure 5 As shown in (a), it surpasses the performance of most non-noble metal HERs; as Figure 5 As shown in (b), the slope of the Co / CoN-NC-20 electrocatalyst Tafel is 109 mV·dec. -1 A smaller Tafel slope is more favorable for the hydrogen evolution reaction (HER) kinetics; for example... Figure 5 As shown in (c), impedance spectroscopy reveals the electrocatalytic reaction kinetics; the smaller the impedance radius, the faster the electron transfer rate. Co / CoN-NC-20 has the smallest impedance radius and exhibits faster electrocatalytic reaction kinetics. Furthermore, as... Figure 5 As shown in (d), by continuously inputting 10mA / cm 2The current density was measured, and the voltage change over time was used to evaluate the long-term stability of the catalyst during application. The figure shows that Co / CoN-NC-20 exhibits strong durability. After 24 hours of constant current testing, its voltage increased by only 1.65% relative to the initial voltage, which proves that the catalyst has excellent HER stability.

[0073] Furthermore, the electrocatalytic water splitting and electrocatalytic water splitting stability performance of the Co / CoN-NC-20 catalyst were further tested. Figure 6 As shown in (b), its water-decomposing current density reaches 10 mA / cm². 2 The required voltage is only 1.657V. Figure 6 (c) Maintaining 10 mA / cm 2 After 24 hours of operation, the voltage of the water electrolysis device maintained good stability, with an increase of only 2.16%, indicating that Co / CoN-NC-20 has good electrocatalytic stability in actual water electrolysis for hydrogen production and has practical application prospects. Figure 6 As shown in (d), after a 24-hour constant current water decomposition stability test, no significant change was found in the material morphology, which still maintained a cubic morphology, further proving its structural stability.

Claims

1. A MOF-derived nitrogen cobalt hetero-nanocase electrocatalyst, characterized in that, The catalyst is based on a zeolite imidazole framework and is transformed into a cubic porous composite material with multiple Co / CoN heterogeneous catalytic centers by pyrolysis after partial substitution of ligands. The preparation method of MOF-derived nitrogen-cobalt heterocell electrocatalysts is as follows: S1: Preparation of ZIF-67 template; S2: Mix a methanol solution of 1H-1,2,3-triazole with a methanol solution of the ZIF-67 template of S1 and react them. S3: After the reaction, the product was centrifuged and dried, and then carbonized under nitrogen protection to obtain MOF-derived nitrogen-cobalt heterogeneous nanocrystal electrocatalyst. The mass ratio of the ZIF-67 template to 1H-1,2,3-triazole is 1:0.5-1.5; Carbonization conditions in S3: temperature 400-600℃, time 1-3h, heating rate 3-5℃ / min.

2. The method for preparing the MOF-derived nitrogen-cobalt heterocell electrocatalyst as described in claim 1, characterized in that, The steps are as follows: S1: Preparation of ZIF-67 template; S2: Mix a methanol solution of 1H-1,2,3-triazole with a methanol solution of the ZIF-67 template of S1 and react them. S3: After the reaction, the product was centrifuged and dried, and then carbonized under nitrogen protection to obtain MOF-derived nitrogen-cobalt heterogeneous nanocrystal electrocatalyst. The mass ratio of the ZIF-67 template to 1H-1,2,3-triazole is 1:0.5-1.5; Carbonization conditions in S3: temperature 400-600℃, time 1-3h, heating rate 3-5℃ / min.

3. The method for preparing the MOF-derived nitrogen-cobalt heterogeneous nanocrystal electrocatalyst according to claim 2, characterized in that, The steps for preparing the ZIF-67 template are as follows: S11: Dissolve 2-methylimidazole in deionized water; S12: Cobalt nitrate hexahydrate and hexadecyl ammonium bromide are dissolved in deionized water and then added to the solution of S11 to carry out the reaction. After the reaction, the mixture is centrifuged, washed and dried to obtain the ZIF-67 template.

4. The method for preparing the MOF-derived nitrogen-cobalt heterocell electrocatalyst according to claim 3, characterized in that, The mass ratio of 2-methylimidazole, cobalt nitrate hexahydrate and hexadecylammonium bromide is 1:0.06-0.08:0.001-0.0015.

5. The method for preparing the MOF-derived nitrogen-cobalt heterocell electrocatalyst according to claim 3, characterized in that, The reaction conditions in S12 are as follows: reaction temperature 20-25℃, stirring for 20-40 min first, then standing for 1-2 h; centrifugation conditions in S12: speed 8000-9500 r / min, time 5-7 min; drying conditions: temperature 50-70℃, time 8-24 h.

6. The method for preparing the MOF-derived nitrogen-cobalt heterocell electrocatalyst according to claim 2, characterized in that, Reaction conditions in S2: temperature 30-35℃, time 15-25min.

7. The method for preparing the MOF-derived nitrogen-cobalt heterocell electrocatalyst according to claim 2, characterized in that, Centrifugation conditions in S3: speed 8000-9500 r / min, time 5-7 min; drying conditions: temperature 50-70℃, time 8-24 h.

8. The application of the MOF-derived nitrogen-cobalt heterogeneous nanocrystal electrocatalyst as described in claim 1 in electrocatalytic water splitting for hydrogen production.

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