MOF-Derived Nitrogen-Rich Single-Atom Electrocatalyst, Preparation Method and Application

Abstract

The present invention discloses a nitrogen-rich single-atom electrocatalyst derived from MOF, a preparation method and an application thereof. The catalyst is obtained by converting a tetrazole-based iron complex into a nitrogen-rich iron single-atom electrocatalyst with polypyridine nitrogen through coordination-confined pyrolysis, and is a dodecahedral porous composite material. The steps of the method for preparing the catalyst are as follows: S1: Preparation of the Fe(2-PTZ)2(H2O)2 precursor; S2: Dissolve the Fe(2-PTZ)2(H2O)2 precursor prepared in S1 in anhydrous methanol, and add zinc nitrate hexahydrate and stir to dissolve, denoted as solution A; S3: Dissolve 2-methylimidazole in an anhydrous methanol solution, denoted as solution B; S4: Add the solution B in S3 to the solution A in S2 for reaction; S5: Centrifuge, dry and calcine and carbonize the product after the reaction in S4 to obtain a nitrogen-rich single-atom electrocatalyst derived from MOF. The catalyst of the present invention has the advantages of being porous, having small particles, rich nitrogen content, many active sites, etc., thereby improving the catalytic performance of the electrocatalyst.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and particularly to a nitrogen-rich single-atom electrocatalyst derived from MOF, a preparation method and an application thereof. Background Art

[0002] With the rapid development of society, fossil fuels (natural gas, petroleum, coal) are being consumed in large quantities, and the resource depletion is becoming increasingly serious. The demand for clean energy by humans is constantly increasing. In order to protect the ecological environment and reduce the degree of human use of fossil fuels, it is the research focus of scientific researchers to search for and develop more sustainable and renewable energy collection, conversion and storage technologies. At present, humans have made great research progress in new energy fields such as wind energy, solar energy, hydropower energy, and tidal energy. In particular, electrochemical energy storage technology has maintained a high growth rate in recent years. It is considered an environmentally friendly and sustainable green energy and can well serve as a medium for energy conversion and storage, thus attracting a great deal of attention. Under this background, designing and developing high-energy-density, low-cost, and sustainable green electrochemical energy storage devices has become a current research hotspot.

[0003] Traditional heterogeneous catalysts usually contain metal particles with a large size distribution. However, only a part of the particles with appropriate sizes can act as catalytic substances, while other particles may be inert or trigger unwanted reactions, resulting in low metal utilization efficiency, high metal consumption, and low mass activity. Therefore, the development of single-atom catalysts can make full use of metal resources and improve the atomic utilization efficiency. Summary of the Invention

[0004] Based on the technical problems existing in the background art, the present invention proposes a nitrogen-rich single-atom electrocatalyst derived from MOF, a preparation method and an application thereof. The prepared catalyst has the advantages of being porous, having small particles, rich nitrogen content, and many active sites, thereby improving the catalytic performance of the electrocatalyst.

[0005] The nitrogen-rich single-atom electrocatalyst derived from MOF proposed by the present invention is obtained by coordinating and confining the pyrolysis conversion of a tetrazole-based iron complex into a nitrogen-rich iron single-atom electrocatalyst with polypyridine nitrogen. This catalyst is a dodecahedral porous composite material.

[0006] The preparation method of the above-mentioned nitrogen-rich single-atom electrocatalyst derived from MOF proposed by the present invention comprises the following method steps:

[0007] S1: Preparation of the Fe(2-PTZ)2(H2O)2 precursor;

[0008] S2: Dissolve the Fe(2-PTZ)2(H2O)2 precursor of S1 in anhydrous methanol, and add zinc nitrate hexahydrate and stir to dissolve, denoted as solution A;

[0009] S3: Dissolve 2-methylimidazole in anhydrous methanol solution, denoted as solution B;

[0010] S4: Add solution B in S3 to solution A in S2 for reaction;

[0011] S5: Centrifuge, dry, and calcine and carbonize the product after reaction in S4 to obtain a nitrogen-rich single-atom electrocatalyst derived from MOF.

[0012] Preferably, the method steps for preparing the Fe(2-PTZ)2(H2O)2 precursor are as follows:

[0013] S11: Dissolve 5-(2-pyridyl)-1H-tetrazole in anhydrous methanol and add an excessive amount of 2,6-dimethylpyridine;

[0014] S12: Add an aqueous solution of ferrous sulfate heptahydrate to the mixture in S11 for reaction. After reaction, wash and dry to obtain the Fe(2-PTZ)2(H2O)2 precursor.

[0015] Preferably, the mass ratio of 5-(2-pyridyl)-1H-tetrazole to ferrous sulfate heptahydrate is 1:1.8 - 2.2.

[0016] Preferably, the reaction conditions in S12 are: stir for 20 - 40 min, and then stand for 4 - 6 h.

[0017] Preferably, the mass ratio of the Fe(2-PTZ)2(H2O)2 precursor, zinc nitrate hexahydrate, and 2-methylimidazole is 1:8 - 80:1 - 100.

[0018] Preferably, the reaction conditions in S4 are: temperature 110 - 130 °C, time 3 - 5 h.

[0019] Preferably, the conditions for centrifugation in S5 are: rotation speed 6000 - 10000 r / min, time 3 - 5 min, and the conditions for drying are: temperature 45 - 55 °C, time 4 - 12 h.

[0020] Preferably, the conditions for calcination in S5 are: temperature 900 - 950 °C, time 1.5 - 2.5 h, and heating rate 3 - 5 °C / min.

[0021] The application of the above-mentioned nitrogen-rich single-atom electrocatalyst derived from MOF proposed by the present invention as an oxygen reduction reaction catalyst in a zinc-air battery.

[0022] Mechanism of action:

[0023] The present invention adopts a strategy of MOF-encapsulated iron(II) complex, and through the coordination constraint effect, the iron(II) complex is converted into a porous iron single-atom catalyst with high nitrogen content by pyrolysis during heating, thus having good electrocatalytic performance.

[0024] The beneficial technical effects of the present invention are as follows:

[0025] (1) The present invention produces the [Fe(2-PTZ)2(H2O)2] precursor through the high-energy and nitrogen-content ligand 5-(2-pyridyl)-1H-tetrazole ligand, which provides both a planar FeN x center and a nitrogen-rich source. Then, during the growth process of ZIF-8, the [Fe(2-PTZ)2(H2O)2] precursor is encapsulated into the nanocages, and after pyrolysis, a dodecahedral porous composite material containing polypyridyl nitrogen and Fe single atoms is obtained. The high-energy ligand can instantaneously release heat during pyrolysis, effectively generating a porous channel structure, and the overall morphology is well maintained before and after pyrolysis.

[0026] (2) The dodecahedral porous composite material prepared by the present invention can be used as an oxygen reduction reaction catalyst in zinc-air batteries and has excellent electrochemical performance under alkaline conditions (0.1 M KOH).

[0027] (3) When preparing the catalyst, the pore structure and specific surface area can be regulated by adjusting the addition ratio of the precursor. Description of the Drawings

[0028] Figure 1 The SEM images proposed by the present invention; (a): Before calcination of FeN x -NC-5, (b): After calcination of FeN x -NC-5 (c): Before calcination of FeN x -NC-3, (d): After calcination of FeN x -NC-3.

[0029] Figure 2 Among them, (a-b) are the TEM images of FeN x -NC-3, (c) is the HRTEM image of FeN x -NC-3, (d) is the selected area electron diffraction SAED image of FeN x -NC-3.

[0030] Figure 3 For the distribution map of different types of nitrogen content in FeN x -NC-3.

[0031] Figure 4 Among them, (a) is the EXAFS R graph of FeN x -NC-3; (b) is the EXAFS R graph of FeN xEXAFS R fitting curve of -NC-3.

[0032] Figure 5 For FeN in 0.1 mol / L potassium hydroxide solution x (a) Polarization curve of oxygen reduction reaction, (b) Tafel slope, (c) methanol toxicity diagram, (d) stability test of oxygen reduction reaction of -NC-3.

[0033] Figure 6 For FeN x (a) Schematic diagram of the structure of a primary zinc-air battery, (b) discharge polarization curve, (c) capacity curve, (d) discharge curve of -NC-3.

[0034] Figure 7 (a - b) in is the modulated electronic structure diagram of FeN x -NC-3 and FeN x (c) is the modulated electronic structure diagram of -NC-3 and FeN x -NC-3 and FeN x (d) is the free energy diagram of ORR of -NC-3 and FeN x -NC-3 and FeN x Total density of states diagram of -NC-3 and FeN Detailed implementation methods

[0035] The reagents and instruments in the embodiments of the present invention are shown in Table 1.

[0036] Table 1 List of reagents and instruments

[0037]

[0038]

[0039] Example 1

[0040] The preparation method of the nitrogen-rich iron single-atom electrocatalyst based on the Fe(2-PTZ)2(H2O)2 precursor proposed by the present invention is as follows:

[0041] S1: Weigh 5 mg of the [Fe(2-PTZ)2(H2O)2] precursor and place it in a beaker, then measure and dissolve it in an anhydrous methanol solution to form a precursor solution;

[0042] S2: Weigh 396.7 mg of Zn(NO3)2·6H2O and add it to the above S1 and stir evenly to obtain a uniform and clear solution;

[0043] S3: Weigh 410.6 mg of 2-methylimidazole and place it in a beaker, then measure and dissolve it in an anhydrous methanol solution to form a ligand solution;

[0044] S4: Add the ligand solution in S3 to the clarified solution in S2 at room temperature, stir for 30 min to mix the materials evenly, and then hydrothermal react at 120 °C for 4 h;

[0045] S5: Centrifuge and dry the precipitate after hydrothermal reaction in S4. The conditions for centrifugation are: rotation speed 8000 r / min, time 3 min, and the conditions for drying are: temperature 50 °C, time 12 h;

[0046] S6: Calcinate and carbonize the dried material in S5 to obtain a dodecahedral porous composite material, denoted as FeN x -NC-1.

[0047] The method for calcination and carbonization is: Load 60 mg of the dried material in S5 into a porcelain boat and place it in a tube furnace for heating reaction. The heating reaction conditions are: temperature 920 °C, time 2 h, heating rate 5 °C / min.

[0048] Example 2

[0049] The preparation method of the nitrogen-rich iron single-atom electrocatalyst prepared based on the Fe(2-PTZ)2(H2O)2 precursor proposed by the present invention is as follows:

[0050] S1: Weigh 10 mg of the [Fe(2-PTZ)2(H2O)2] precursor and place it in a beaker, then measure and dissolve it in an anhydrous methanol solution to form a precursor solution;

[0051] S2: Weigh 396.7 mg of Zn(NO3)2·6H2O and add it to the above S1 and stir evenly to obtain a uniform clarified solution;

[0052] S3: Weigh 410.6 mg of 2-methylimidazole and place it in a beaker, then measure and dissolve it in an anhydrous methanol solution to form a ligand solution;

[0053] S4: Add the ligand solution in S3 to the clarified solution in S2 at room temperature, stir for 30 min to mix the materials evenly, and then hydrothermal react at 120 °C for 4 h;

[0054] S5: Centrifuge and dry the precipitate after hydrothermal reaction in S4. The conditions for centrifugation are: rotation speed 8000 r / min, time 3 min, and the conditions for drying are: temperature 50 °C, time 12 h;

[0055] S6: Calcinate and carbonize the dried material in S5 to obtain a dodecahedral porous composite material, denoted as FeN x -NC-2.

[0056] The method of calcination carbonization is as follows: Load 60 mg of the dried material in S5 into a porcelain boat and place it in a tube furnace for heating reaction. The heating reaction conditions are: temperature 920 °C, time 2 h, and heating rate 5 °C / min.

[0057] Example 3

[0058] The preparation method of the nitrogen-rich iron single-atom electrocatalyst prepared based on the Fe(2-PTZ)2(H2O)2 precursor proposed by the present invention is as follows:

[0059] S1: Weigh 30 mg of the [Fe(2-PTZ)2(H2O)2] precursor and place it in a beaker, then measure and dissolve it in an anhydrous methanol solution to form a precursor solution;

[0060] S2: Weigh 396.7 mg of Zn(NO3)2·6H2O and add it to the above S1 and stir evenly to obtain a uniform and clear solution;

[0061] S3: Weigh 410.6 mg of 2-methylimidazole and place it in a beaker, then measure and dissolve it in an anhydrous methanol solution to form a ligand solution;

[0062] S4: Add the ligand solution in S3 to the clear solution in S2 at room temperature, stir for 30 min to make the materials mix evenly, and then hydrothermal react at 120 °C for 4 h;

[0063] S5: Centrifuge and dry the precipitate after hydrothermal reaction in S4. The centrifugation conditions are: rotation speed 8000 r / min, time 3 min, and the drying conditions are: temperature 50 °C, time 12 h;

[0064] S6: Calcinate and carbonize the dried material in S5 to obtain a dodecahedral porous composite material, denoted as FeN x -NC-3.

[0065] The method of calcination carbonization is as follows: Load 60 mg of the dried material in S5 into a porcelain boat and place it in a tube furnace for heating reaction. The heating reaction conditions are: temperature 920 °C, time 2 h, and heating rate 5 °C / min.

[0066] Example 4

[0067] The preparation method of the nitrogen-rich iron single-atom electrocatalyst prepared based on the Fe(2-PTZ)2(H2O)2 precursor proposed by the present invention is as follows:

[0068] S1: Weigh 50 mg of the [Fe(2-PTZ)2(H2O)2] precursor and place it in a beaker, then measure and dissolve it in an anhydrous methanol solution to form a precursor solution;

[0069] S2: Weigh 396.7 mg of Zn(NO3)2·6H2O and add it to the above S1, then stir evenly to obtain a homogeneous and clear solution;

[0070] S3: Weigh 410.6 mg of 2-methylimidazole and place it in a beaker, then measure and dissolve it in anhydrous methanol solution to form a ligand solution;

[0071] S4: At room temperature, add the ligand solution in S3 to the clear solution in S2, stir for 30 min to make the materials mix evenly, and then hydrothermal react at 120 °C for 4 h;

[0072] S5: Centrifuge and dry the precipitate after hydrothermal reaction in S4. The conditions for centrifugation are: rotation speed 8000 r / min, time 3 min, and the conditions for drying are: temperature 50 °C, time 12 h;

[0073] S6: Calcinate and carbonize the dried material in S5 to obtain a dodecahedral porous composite material, denoted as FeN x -NC-4.

[0074] The method for calcination and carbonization is: Load 60 mg of the dried material in S5 into a porcelain boat and place it in a tube furnace for heating reaction. The heating reaction conditions are: temperature 920 °C, time 2 h, heating rate 5 °C / min.

[0075] Example 5

[0076] The preparation method of the nitrogen-rich iron single-atom electrocatalyst based on the Fe(2-PTZ)2(H2O)2 precursor proposed by the present invention is as follows:

[0077] S1: Weigh 30 mg of ferrous sulfate heptahydrate and place it in a beaker, then measure and dissolve it in anhydrous methanol solution to form a precursor solution;

[0078] S2: Weigh 396.7 mg of Zn(NO3)2·6H2O and add it to the above S1, then stir evenly to obtain a homogeneous and clear solution;

[0079] S3: Weigh 410.6 mg of 2-methylimidazole and place it in a beaker, then measure and dissolve it in anhydrous methanol solution to form a ligand solution;

[0080] S4: At room temperature, add the ligand solution in S3 to the clear solution in S2, stir for 30 min to make the materials mix evenly, and then hydrothermal react at 120 °C for 4 h;

[0081] S5: Centrifuge and dry the precipitate after hydrothermal reaction in S4. The conditions for centrifugation are: rotation speed 8000 r / min, time 3 min, and the conditions for drying are: temperature 50 °C, time 12 h;

[0082] S6: Calcinate and carbonize the material dried in S5 to obtain a dodecahedral porous composite material, denoted as FeN x -NC-5.

[0083] The method of calcination and carbonization is as follows: Load 60 mg of the material dried in S5 into a porcelain boat and place it in a tube furnace for heating reaction. The heating reaction conditions are: temperature 920 °C, time 2 h, heating rate 5 °C / min.

[0084] As Figure 1 can be seen, when completely using metallic iron as the metal source, the sample presents a dodecahedron and has a small size, as Figure 1 (a) shows; After high-temperature carbonization treatment, it can be found that the surface shrinks, as Figure 1 (b) shows; When adding a precursor, the sample presents a similar dodecahedron, as Figure 1 (c) shows; In addition, after high-temperature carbonization treatment, it can be found that the sample maintains a complete form without being damaged, as Figure 1 (d) shows, and the surface becomes rough, that is, the sample containing the precursor has significantly richer pores after carbonization.

[0085] In addition, the oxygen reduction performance of the sample was characterized using a three-electrode system on a CHI760D electrochemical workstation and a rotating ring-disk electrode (RDE). Weigh 5 mg of the sample obtained from the experiment, add 480 μl of ethanol, 480 μl of H2O, and 40 μl of perfluorosulfonic acid (Nafion) solution, and ultrasonicate for 30 minutes to make it completely dispersed. Drop the sample suspension evenly on the rotating ring-disk electrode twice, 5 μl each time, and dry it with a baking lamp. In the three-electrode system, the working electrode is the disk electrode, the counter electrode uses a graphite electrode, and the reference electrode uses a saturated calomel electrode (SCE). The electrolyte uses an O2-saturated 0.1 M KOH solution (pH = 13). The potential used in this study is converted to the corresponding reversible hydrogen electrode (RHE) value through the formula E RHE = E SCE + 0.244 + 0.0591*pH, where E SCE is the potential applied to the ESC reference electrode. The rotating ring-disk electrode was measured at different rotation speeds from 400 rpm to 1600 rpm. Chronopotentiometry was used for long-term stability testing. The zinc-air battery uses zinc powder, 6.0 M KOH solution, and the catalyst is loaded on a nickel foam substrate.

[0086] For the coated precursor complex, transmission electron microscope (TEM) images show that the pyrolyzed sample FeN x-NC-3 retains its original dodecahedral shape after heat treatment. More cavities can be observed on the surface and inside, which is attributed to the pyrolysis of the [Fe(2-PTZ)2(H2O)2] precursor, where 2-PTZ is a high-energy ligand. The rapid decomposition and heat release lead to the formation of cavity-rich structures, as Figure 2 (a-b) shows. In the high-resolution transmission electron microscopy (HRTEM) image, there are no nanoparticles or nanoclusters in the entire carbon matrix of FeN x -NC-3, as Figure 2 (c) shows. It can be seen from the selected area electron diffraction (SAED) image that there are also no obvious diffraction rings, further confirming that no Fe species are formed in the structure, as Figure 2 (d) shows. This dodecahedral porous rigid structure can prevent the aggregation of Fe clusters during high-temperature heat treatment, thus preparing an isolated single-atom iron catalyst.

[0087] FeN x -NC-3 has a nitrogen content as high as 13.8%. Among the nitrogen species, the content of pyridine nitrogen reaches 5.35% ( Figure 3 ). The N species in the carbon material play an important role in improving the electrocatalytic performance: pyridine nitrogen in the carbon matrix is very important for the formation of active Fe-N sites and surface wetting, which is beneficial to improving the electrical conductivity and diffusion transport of the catalyst. In addition, graphitic nitrogen affects the geometric and electronic structures of the carbon skeleton, increasing the limiting current density of ORR.

[0088] Using Fourier transform (FT) and wavelet transform (WT) methods, X-ray absorption fine structure (EXAFS) further reveals the local structure of the Fe sites. In the EXAFS R graph, compared with the Fe-Fe path at on the Fe foil (reference), FeN x -NC-3 shows an obvious peak near , which can be assigned to the first coordination shell of Fe-N. The absence of Fe-Fe metal bonds confirms the atomic dispersion of single Fe atom sites in FeN x -NC-3, as Figure 4 (a) shows. WT EXAFS analysis shows that Fe atoms exist in the form of mononuclear centers and there is no iron-derived crystal structure. EXAFS fitting analysis shows the coordination number and bonding distance of the central Fe atom in FeN x -NC-3 to adjacent scattering atoms, and the coordination number and bonding distance of the first shell of Fe-N are 4.1±0.2 and as Figure 4 (b) shows. These results verify that the single-atom Fe site in FeN x -NC-3 has a FeN4 configuration.

[0089] The ORR performance of the product is as follows: The ORR activity of FeN x -NC-3 in 0.1 M KOH saturated with O2 was studied using a rotating disk electrode (RDE). The linear sweep voltammetry (LSV) results showed that FeN x -NC-3 exhibited the best activity in terms of the onset potential (E onset ) and the half-wave potential (E 1 / 2 ). As shown in Figure 5 (a), the E x of FeN onset -NC-3 was 1.01 V and the E 1 / 2 was 0.928 V, exceeding most non-precious metal ORRs; as shown in Figure 5 (b), the Tafel slope of the electrocatalyst was 55.2 mV·dec -1 , and the smaller the Tafel slope, the more favorable for ORR kinetics; as shown in Figure 5 (c), FeN x -NC-3 had good methanol poisoning tolerance, which was beneficial to the practical application of fuel cells. In addition, as shown in Figure 5 (d), the long-term stability was evaluated by chronoamperometry at 0.8 V, and FeN x -NC-3 showed stronger durability, retaining 93.7% of its original value, demonstrating the excellent ORR stability of this catalyst.

[0090] In addition, the discharge polarization and discharge curve performance of the zinc-air battery with the catalyst were further tested. As shown in Figure 6 (b), its peak power density at 370 mA / cm 2 was 267 mW / cm 2 ; the specific capacity of the assembled primary battery was measured at 10 mA / cm 2 . If normalized to the consumed mass of zinc, as shown in Figure 6 (c), the specific capacity of the FeN x -NC-3 sample was 938 mAh / g Zn ; as shown in Figure 6 (d), at 10 mA / cm 2 , the initial potential of the FeN x -NC-3-based zinc-air battery was 1.4013 V; after continuous operation for 143 h, this potential could maintain good stability, with a decay of 17.7%, indicating that FeN x -NC-3 had good electrocatalytic stability for the ORR of actual zinc-air batteries.

[0091] To further understand FeN xThe ORR mechanism of -NC-3 reveals the crucial role of nitrogen content in achieving high ORR activity and selectivity through DFT calculations. It is found that FeN x The rate-determining step of -NC-3 is the desorption of OH*, indicating that the intrinsic adsorption of FeN4 to OH* is too strong, restricting its ORR reduction potential. FeN x -NC-5 and FeN x -NC-3 have activities of 0.57 eV and 0.69 eV respectively (as shown in Figure 7 (c)). In addition, it can be clearly seen that the increase in nitrogen content leads to a decrease in the adsorption of all intermediates. To further clarify the above reasons, the electronic structures of the two materials were calculated. As shown in Figure 7 (d), starting from the density of states, adding N can not only improve the conductivity of the material, but also adjust and reduce the d-band center, weaken its adsorption to intermediates, and optimize its ORR performance, which is in good agreement with the experimental results.

Claims

1. A preparation method of a nitrogen-rich single-atom electrocatalyst derived from MOF, characterized in that, The nitrogen-rich single-atom electrocatalyst is prepared by converting a tetrazole-based iron complex into a nitrogen-rich iron single-atom electrocatalyst with polypyridine nitrogen through coordination-confined pyrolysis. The catalyst is a dodecahedral porous composite material; The method steps of the nitrogen-rich single-atom electrocatalyst are as follows: S1: Preparation of the Fe(2-PTZ)2(H2O)2 precursor; S2: Dissolve the Fe(2-PTZ)2(H2O)2 precursor of S1 in anhydrous methanol, and add zinc nitrate hexahydrate and stir to dissolve, denoted as solution A; S3: Dissolve 2-methylimidazole in an anhydrous methanol solution, denoted as solution B; S4: Add the solution B in S3 to the solution A in S2 and carry out the reaction; S5: Centrifuge, dry, and calcine and carbonize the product after the reaction in S4 to obtain a MOF-derived nitrogen-rich single-atom electrocatalyst; The method steps for preparing the Fe(2-PTZ)2(H2O)2 precursor are as follows: S11: Dissolve 5-(2-pyridyl)-1H-tetrazole in anhydrous methanol, and add an excessive amount of 2,6-dimethylpyridine; S12: Add an aqueous solution of ferrous sulfate heptahydrate to the mixture in S11 for reaction. After the reaction, wash and dry to obtain the Fe(2-PTZ)2(H2O)2 precursor; The mass ratio of the Fe(2-PTZ)2(H2O)2 precursor, zinc nitrate hexahydrate, and 2-methylimidazole is 1:8-80:1-100.

2. The preparation method of the nitrogen-rich single-atom electrocatalyst based on MOF derivative according to claim 1, wherein, The mass ratio of 5-(2-pyridyl)-1H-tetrazole to ferrous sulfate heptahydrate is 1:1.8-2.

2.

3. The preparation method of the nitrogen-rich single-atom electrocatalyst based on MOF derivative according to claim 1, characterized in that, The reaction conditions in S12 are: stir for 20-40 min, and then stand for 4-6 h.

4. The preparation method of the nitrogen-rich single-atom electrocatalyst based on MOF derivation according to claim 1, wherein The reaction conditions in S4 are: temperature 110-130 °C, time 3-5 h.

5. The preparation method of the nitrogen-rich single-atom electrocatalyst based on MOF derivation according to claim 1, characterized in that The centrifugation conditions in S5 are: rotation speed 6000-10000 r / min, time 3-5 min, and the drying conditions are: temperature 45-55 °C, time 4-12 h.

6. The preparation method of the nitrogen-rich single-atom electrocatalyst based on MOF derivation according to claim 1, characterized in that The calcination conditions in S5 are: temperature 900-950 °C, time 1.5-2.5 h, heating rate 3-5 °C / min.

7. A nitrogen-rich single-atom electrocatalyst derived from MOF, characterized in that, Prepared by using the preparation method described in any one of claims 1-6.

8. Application of the MOF-derived nitrogen-rich single-atom electrocatalyst as claimed in claim 7 as an oxygen reduction reaction catalyst in a zinc-air battery.

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