Efficient FeCrNiCoMn high-entropy monatomic nitrogen-doped carbon-based electrocatalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalysts and fuel cells, and particularly relates to an efficient FeCrNiCoMn high-entropy monatomic nitrogen-doped carbon-based electrocatalyst as well as a preparation method and application thereof. Mixing and dissolving the nitrogen-containing organic ligand and zinc salt in a solvent; dissolving ferric salt, chromium salt, nickel salt, cobalt salt and manganese salt in a solvent, then mixing with the solution, and stirring until the solvent is volatilized and the mixture is adhesive; carrying out first heat treatment on the adhesive product to obtain a powdery precursor; and carrying out second heat treatment on the powdery precursor in an inert atmosphere to obtain the high-entropy monatomic nitrogen-doped carbon-based electrocatalyst. According to the invention, the air battery has excellent stability and catalytic activity by utilizing mutual containment among high-entropy monatomic atoms, and has excellent OER performance due to surface reconstruction and lattice oxidation phenomena in an OER reaction, so that the defect of single catalytic performance of an electrocatalyst is overcome, and the air battery has charge-discharge performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of catalysts and fuel cells, and particularly relates to a high-efficiency FeCrNiCoMn high-entropy single-atom nitrogen-doped carbon-based electrocatalyst as well as a preparation method and application thereof. BACKGROUND

[0002] In order to achieve the goal of carbon neutralization and realize zero carbon emission, high requirements are put forward for clean and renewable energy technologies. Rechargeable zinc-air batteries (ZABs) have the advantages of high safety, zero carbon emission and considerable theoretical energy density (1086 Wh·kg -1 ), and are considered to be one of the most promising electrochemical energy storage and conversion devices. Reversible oxygen electrochemistry, i.e. oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), plays a key role in sustainable energy conversion and storage devices such as renewable fuel cells and rechargeable metal-air batteries. However, the slow kinetics of the ORR and OER processes, which involve four proton-coupled electron transfer (PCET) steps, poses a huge challenge to the practical efficiency of these sustainable electrochemical devices. It is crucial to design a bifunctional electrocatalyst that accelerates both ORR and OER, but fundamentally, it is hindered by the linear scaling between the energies of the PCET steps determined by the different rates of the two opposite reactions, which hinders the independent optimization of these energies to achieve ideal bifunctional activity. Noble metals such as platinum and iridium (the most advanced electrocatalysts for ORR and OER, respectively) perform poorly in the reverse reaction. A common strategy to overcome this challenge is to develop noble metal-based composite catalysts by mixing ORR and OER active components. However, it is still imperative to design cost-effective bifunctional catalysts using abundant elements on Earth.

[0003] High-symmetry monolayer graphene has SP 2Hybridized graphitic carbons possess unique delocalized p-electron aromaticity. Combining their good electrical conductivity, structural stability, and environmental friendliness, this makes carbon-based materials promising candidates for low-cost electrocatalysts for ORR and OER. However, symmetrically protected graphitic carbons have extremely high stability and inertness due to their stable p-conjugated electron network. In order to trigger the catalytic activity of carbon-based materials, various strategies aiming to destroy the delocalization of p-conjugated electron network have emerged, such as heteroatom doping, defects, edge and morphology modification (formation of core-shell structure, hollow structure, etc.). Investigation of the symmetry evolution of previously developed carbon catalysts shows that the electrocatalytic activity increases with the decrease of basal plane symmetry. From the highest symmetry of inert original graphene, to nitrogen-doped carbon (NC) materials (including pyridinic nitrogen, pyrrolic nitrogen), they show good electrocatalytic activity for ORR and OER. To metal single-atom (M-SA) catalysts, they have better noble metal-like activity, and recently developed diatomic catalysts, they usually have higher ORR and OER activity. This phenomenon shows that the catalyst activity is positively correlated with the reduction of symmetry, in order to further improve the performance of carbon-based catalysts, we can reduce its basal plane symmetry to a minimum. In this case, the chaotic system with high-entropy atoms will be the ideal state we are looking for.

[0004] High-entropy single-atom nitrogen-doped carbon electrocatalysts have excellent catalytic activity, but the commonly used catalysts are still limited to single oxygen reaction catalysts, and cannot achieve excellent dual-function catalytic properties. And in the process of oxygen reaction, the phenomenon of atomic aggregation occurs, thereby reducing the active points. Therefore, it is crucial to design a group of high-entropy single-atom catalysts with mutual restriction and synergistic effect between elements.

[0005] There are many technologies for preparing high-entropy transition metal atom nitrogen-doped carbon materials in the prior art, and the method for preparing the transition metal atom nitrogen-doped carbon material needs to consider the high dispersity of metal atoms, the uniformity of nitrogen doping, and the stability of the structure. The following are several common preparation technologies:

[0006] High-entropy precursor pyrolysis method: by constructing a multi-metal uniformly mixed organic / inorganic precursor (such as multi-metal salt, multi-metal MOF, polymer complex, etc.) for pyrolysis, realizing the uniform dispersion of multiple metal atoms under high-temperature inert atmosphere.

[0007] Multi-metal MOF derivation method: taking metal organic framework as a precursor template, constructing a MOF structure with multi-metal nodes, generating M-N-C structure in situ carbonization while maintaining the order of the skeleton, which has the advantage of forming highly dispersed multi-metal atomic clusters or single atoms.

[0008] Salt dissolution assisted method: molten salt can be used as an ionic liquid reaction medium at high temperature, stabilizing metal cations and promoting the uniform distribution of multi-metal single atoms. By mixing various metal precursors with salt (NaCl, KCl, LiCl, etc.) and then performing heat treatment under an inert atmosphere, followed by water washing to remove the salt, a high-entropy single-atom material can be obtained. The advantages of this method include the ability to control the uniformity of the composition, the avoidance of metal agglomeration at high temperatures, and the provision of a flexible reaction environment and template effect by the molten salt.

[0009] Electrospinning method: electrospinning technology is a method that can produce continuous nanofibers. It is a mature technology that can synthesize ultra-fine carbon nanofibers with a diameter of several tens of nanometers and specific structures and compositions. The prepared nanofiber membranes have the advantages of wide application range and stable film-forming performance.

[0010] Non-noble high-entropy single-atom nitrogen-doped carbon electrocatalysts have good ORR and OER catalytic activity and do not require the use of expensive noble metal catalysts. Therefore, they have important application potential in the field of energy conversion such as fuel cells and metal-air batteries. Despite their advantages, current non-noble high-entropy single-atom nitrogen-doped carbon electrocatalysts still face performance bottlenecks: the catalysts prepared by existing technologies not only have low activity and poor catalytic stability, but also have problems such as insufficient stability, low energy density, power density, and specific capacity in zinc-air batteries assembled with them; and most of the prepared catalysts cannot achieve high dispersion of such a large number of components, and cannot simultaneously possess ORR and OER catalytic performance. In addition, the preparation process of the catalysts is generally complex, which further restricts the industrialization process of zinc-air batteries.

[0011] Under this background, the development of efficient high-entropy non-noble metal catalysts has become a research focus in the field. Therefore, the preparation of high-entropy single-atom nitrogen-carbon-based materials with high catalytic activity and stability is closely related to the innovative development of new energy storage technology, and has important strategic significance for breaking through the current technical bottlenecks in the energy field SUMMARY

[0012] The purpose of the present application is to provide an efficient FeCrNiCoMn high-entropy single-atom nitrogen-doped carbon-based electrocatalyst, its preparation method and application. The mutual restraint between high-entropy single atoms makes them have excellent stability and catalytic activity. In addition, surface reconstruction and lattice oxidation occur during the OER reaction, which makes the catalyst have excellent OER performance, making up for the shortcomings of single catalytic performance of electrocatalysts.

[0013] To achieve the above purpose, the present application provides a preparation method of FeCrNiCoMn high-entropy single-atom nitrogen-doped carbon-based electrocatalyst, which comprises the following steps:

[0014] Step 1: mix and dissolve nitrogen-containing organic ligands and zinc salt in a solvent;

[0015] Step 2, dissolving the iron salt, chromium salt, nickel salt, cobalt salt, manganese salt in a solvent, then mixing with the solution of step 1, stirring until the solvent volatilizes to make the mixture sticky;

[0016] Step 3, the sticky product of step 2 is subjected to a first heat treatment to obtain a powder precursor;

[0017] Step 4, the powder precursor is subjected to a second heat treatment under an inert atmosphere to obtain a FeCrNiCoMn high-entropy single-atom nitrogen-doped carbon-based electrocatalyst.

[0018] Further, in step 1, the nitrogen-containing organic ligand is dimethyl imidazole or diethyl imidazole, and the zinc salt is one or more of zinc nitrate, zinc chloride or zinc acetate.

[0019] Further, in step 1, the mass ratio of the zinc salt and the nitrogen-containing organic ligand is greater than 0 and less than 3.2.

[0020] Further, in step 2, the molar ratio of the iron salt, chromium salt, nickel salt, cobalt salt, manganese salt is (0-1):(0-1):(0-1):(0-1):(0-1), preferably (0.6-0.8):(0.2-0.4):(0.1-0.3):(0.1-0.3):(0.1-0.3).

[0021] The molar ratio of the zinc salt and one of the salts in step 2 is greater than or equal to 2:1.

[0022] Further, in step 2, the iron salt, chromium salt, nickel salt, cobalt salt, manganese salt are each independently selected from one or more of nitrate, chloride, acetate, acetylacetone salt; and the solvent of steps 1 and 2 is water, methanol, acetone or ethanol.

[0023] Further, in step 2, the stirring time is 3-12h.

[0024] Further, in step 3, the first heat treatment temperature is 150-200℃, and the holding time is 0.5-2h.

[0025] Further, in step 4, the second heat treatment has a heating rate of 2.5-7.5℃ / min, a final temperature of 900-1000℃, and a holding time of 1-5h; after calcination is completed, the temperature is lowered to room temperature at a cooling rate of 2.5-7.5℃ / min.

[0026] The application also provides a FeCrNiCoMn high-entropy single-atom nitrogen-doped carbon-based electrocatalyst prepared by the preparation method of any one of the above.

[0027] The application also provides application of the FeCrNiCoMn high-entropy single-atom nitrogen-doped carbon-based electrocatalyst in hydrogen fuel cells, metal-air batteries, water electrolysis, air purification, wastewater treatment, and storage and conversion of renewable energy.

[0028] Specifically, in a hydrogen fuel cell (such as a proton exchange membrane fuel cell, PEMFC), the ORR catalyst is used in the cathode catalyst layer to promote the occurrence of hydrogen oxidation and oxygen reduction reactions. The ORR generally occurs at the cathode to generate water and electricity; in a metal-air battery (such as a zinc-air battery or a lithium-air battery), the ORR catalyst acts as a cathode catalyst to promote the reduction of oxygen to generate hydroxide or peroxide, thereby storing energy; in the process of water electrolysis, the ORR catalyst is used in the cathode to promote the reduction of water (oxygen evolution reaction, OER), and the oxygen evolution reaction (OER) at the anode. The oxygen reduction reaction and the oxygen evolution reaction complement each other in this process, and the catalyst must have good adaptability between the two; in the process of environmental governance such as air purification and wastewater treatment, the ORR catalyst can be used to reduce the oxidation or degradation of pollutants, and catalyze the reaction of oxygen or other oxidants.

[0029] Potential fields: storage and conversion of renewable energy, flexible electronic devices, portable energy devices, seawater batteries, and deep-sea energy collection.

[0030] Compared with the prior art, the above technical scheme conceived by the application mainly has the following technical advantages:

[0031] 1. The application uses zinc nitrate hexahydrate, dimethyl imidazole, iron nitrate nonahydrate, chromium nitrate nonahydrate, nickel nitrate hexahydrate, cobalt nitrate hexahydrate, and manganese nitrate tetrahydrate as raw materials, and ultrapure water as a solvent. After stirring uniformly, a catalyst precursor is prepared by a thermal expansion method, and an iron-zirconium single-atomic sulfur-nitrogen-doped carbon oxygen reduction electrocatalyst is prepared by a further high-temperature carbonization pyrolysis process. The introduction of high-entropy single atoms and nitrogen atom coordination greatly improves the activity and stability of the catalyst. The mutual restraint between high-entropy single atoms makes the catalyst have excellent stability and catalytic activity. In the OER reaction, surface reconstruction and lattice oxidation occur, which makes the catalyst have excellent OER performance, making up for the shortcomings of single catalytic performance of the electrocatalyst. The air battery has chargeable and dischargeable performance, which helps to improve the reversibility of the device.

[0032] 2. The catalyst prepared by the application exhibits excellent oxygen reduction performance, and the half-wave potential can reach 0.86 V. The OER overpotential is 278 mV. The impedance R ct is 10.9 Ω, and the Tafel slope is 77.9 mVdec -1The power density curve of the assembled zinc-air battery shows that Fe,Zr-SNC has a power density of 300mAcm -2 A current density of 171 mW cm was obtained. -2 The power density is better than that of Pt / C@RuO2 (200mAcm -2 129mWcm -2 These results highlight the superior potential of Fe,Zr-SNC as an alternative to precious metal-based electrocatalysts. The non-precious metal catalysts prepared in this invention exhibit superior oxygen reduction performance compared to platinum-based precious metals, and the assembled zinc-air battery also outperforms commercial platinum-carbon precious metal catalysts. The non-precious metal-based iron-zirconium double single-atom nitrogen-doped carbon-oxygen reduction electrocatalyst prepared in this invention offers valuable applications with low cost, high performance, high stability, and simple process. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flow chart of the preparation process of the FeCrNiCoMn high-entropy single-atom nitrogen-doped carbon-based electrocatalyst of the present invention.

[0034] Figure 2 This is the TEM-EDS detection diagram of the material elements obtained in Example 1.

[0035] Figure 3 This is the TEM-EDS detection image of the material elements after surface reconstruction after the OER reaction.

[0036] Figure 4 is the XRD pattern of the catalyst.

[0037] Figure 5 This is the Raman spectrum of the catalyst.

[0038] Figure 6 This is the LSV diagram of the catalyst during ORR test.

[0039] Figure 7 LSV diagram for OER test.

[0040] Figure 8 This is the EIS impedance diagram.

[0041] Figure 9 is the Tafel slope plot.

[0042] Figure 10 The charge and discharge curves and discharge power density diagram obtained from the zinc-air battery test. DETAILED DESCRIPTION

[0043] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0044] The present application provides a kind of efficient FeCrNiCoMn high-entropy single-atom nitrogen-doped carbon-based electrocatalyst and its preparation method and application. With zinc nitrate hexahydrate, dimethyl imidazole, iron nitrate nonahydrate, chromium nitrate nonahydrate, nickel nitrate hexahydrate, cobalt nitrate hexahydrate and manganese nitrate tetrahydrate as raw materials. Specifically as follows:

[0045] 1) dimethyl imidazole provides carbon base and nitrogen source, and zinc nitrate hexahydrate can react with dimethyl imidazole, and zinc oxide particles are generated in the process of generating precursor reaction, and in the further high-temperature carbonization process, zinc oxide is reduced to zinc by reacting with carbon, and because the carbonization temperature is higher than the boiling point of zinc, it is formed in a porous structure by volatilization in thermal degradation. The ratio of zinc nitrate hexahydrate to diethyl imidazole should satisfy: 0 < zinc nitrate hexahydrate: diethyl imidazole < 3.2:1 (herein the unit is g), it is worth noting that zinc nitrate hexahydrate is an explosive compound, and the amount should be controlled within 3.2g.

[0046] 2) iron nitrate nonahydrate, chromium nitrate nonahydrate, nickel nitrate hexahydrate, cobalt nitrate hexahydrate and manganese nitrate tetrahydrate are used as sources of high-entropy metal atoms, and the ratio should be controlled in 0 < Fe < 1, 0 < Cr < 1, 0 < Ni < 1, 0 < Co < 1, 0 < Mn < 1 (unit: mmol), in addition, iron nitrate nonahydrate can also be used other compounds containing iron element dissolved in ultrapure water, including: ferric chloride, acetylacetone iron, ferric acetate, etc., and the rest of the metal elements are the same as above.

[0047] 3) ultrapure water is used as solvent, here ultrapure water only acts as a solvent, does not react with dimethyl imidazole, zinc nitrate hexahydrate, iron nitrate nonahydrate, chromium nitrate nonahydrate, nickel nitrate hexahydrate, cobalt nitrate hexahydrate and manganese nitrate tetrahydrate in raw materials, and the solvent that can cause complexation reaction of metal ions also cannot be used. In addition to using ultrapure water as solvent, methanol, acetone, ethanol, etc. can also be selected.

[0048] 4) after stirring uniformly, it is collected by thermal expansion method, i.e. dimethyl imidazole and zinc nitrate hexahydrate directly react with heat, in this process, gel-like changes to powder-like, and the volume expands by about 10 times after reaction. After cooling to room temperature, the powder sample is collected as catalyst precursor,

[0049] 5) In order to prepare a FeCrNiCoMn high-entropy single-atom nitrogen-doped carbon-based electrocatalyst, the catalyst precursor obtained in step 4 is subjected to further high-temperature carbonization pyrolysis. The precursor is placed in a tube furnace and heated from room temperature to 900-1000°C at a heating rate of 2.5-7.5°C / min in an inert atmosphere, and the holding time is 1-5h. After calcination, the temperature is reduced to room temperature at a cooling rate of 2.5-7.5°C / min. The obtained material is the desired FeCrNiCoMn high-entropy single-atom nitrogen-doped carbon-based electrocatalyst.

[0050] Example 1

[0051] An efficient high-entropy single-atom nitrogen-doped carbon-based electrocatalyst, the specific process steps are as follows:

[0052] 1) Mix 1g of dimethylimidazole with 3g of zinc nitrate hexahydrate, 10ml of ultrapure water thoroughly;

[0053] 2) Dissolve 0.077mmol of iron nitrate nonahydrate, 0.033mmol of chromium nitrate nonahydrate, 0.022mmol of nickel nitrate hexahydrate, 0.022mmol of cobalt nitrate hexahydrate and 0.022mmol of manganese nitrate tetrahydrate in ultrapure water and ultrasonic, and mix them uniformly.

[0054] 3) Pour the liquid in step 2 into the solution in step 1, and stir, during which the solution volatilizes until it becomes sticky. The stirring time is about 6h.

[0055] 4) Place the stirred beaker in a large beaker and place it in an oven at 170°C for 1h. During this period, a solid-state pyrolysis reaction occurs, and the sticky substance is converted into a powder, which is the precursor of the high-entropy single-atom electrocatalyst.

[0056] 5) Weigh a certain amount of 300-500mg of the precursor powder in a corundum boat, use a tube furnace, and heat it from room temperature to 950°C at a heating rate of 5°C / min in an argon atmosphere, and hold for two hours. When the temperature drops to room temperature, the high-entropy single-atom electrocatalyst can be collected.

[0057] The catalyst after high-temperature pyrolysis is weighed, and the yield is about 12%. At the same time, the catalyst can be directly tested without subsequent treatment.

[0058] Further, by changing the types and amounts of metal salts in step 2, the effects of different metal atoms on the performance of the obtained catalyst are explored, and the specific formulations are shown in Table 1.

[0059] Table 1

[0060]

[0061]

[0062] The pyrolyzed catalyst was characterized by XRD, SEM, TEM, and spherical aberration, indicating that FeCrNiCoMn existed in the form of single atoms, and its electrochemical activity and stability were tested. The test results are as follows Figures 2-5 , Figure 4 from top to bottom in the figure correspond to examples 5, 6, 7, 1, 13 and 4, respectively. X-ray diffraction (XRD) was used to characterize the carbon structure of the high-entropy single-atom series samples. As shown in Figure 4 , the XRD spectra of Fe, Zr-SNC, Fe-SNC, Zr-SNC and SNC are similar, with two broad peaks near 24° and 44°, which belong to the (002) and (101) reflections of the amorphous graphite carbon matrix, respectively. No metal crystalline phase or cluster was detected.

[0063] The presence of metal atoms makes there be more pyridine nitrogen / pyrrole nitrogen inside, which usually exists in defects, so from the Raman results, it can be preliminarily judged that the defect degree of FeCrNiCoMn-7:3 is larger (as shown in Figure 5 ).

[0064] Further, the obtained FeCrNiCoMn high-entropy single-atom nitrogen-doped carbon-based electrocatalyst was assembled as the cathode of a zinc-air battery, and the test results are as follows Figures 6-10 .

[0065] The prepared FeCrNiCoMn high-entropy single-atom nitrogen-doped carbon-based electrocatalyst has an ORR half-wave potential of 0.86 V vs. RHE, an OER overpotential of 278 mV, a potential difference between ORR and OER of only 0.64 mV, and a Tafel of 77.9 mVdec -1 . The assembled zinc-air battery has an open-circuit voltage of 1.49 V and a power density of 171.7 mWcm -2 , and the charge-discharge stability is maintained for more than 500 hours. The ORR and OER performance of 2-5 components were compared, and the catalyst of the 5-component structure surface has higher catalytic activity and stability compared with the remaining components, as shown in Figure 6 and Figure 7 .

[0066] The role of each atom: iron single atom: as the main active center, anchored on the amorphous porous carbon carrier, forming a primary coordination structure with zirconium and nitrogen; Cr atom: improve the oxidation resistance of the catalyst and enhance the stability of the carrier; Ni atom: optimize the adsorption energy, adjust the reaction path, commonly used to enhance the ORR / OER synergy under alkaline conditions; Co atom: improve electronic conductivity and reaction kinetics, accelerate intermediate conversion; Mn atom: improve the adsorption selectivity of oxygen species, and temperature carbon carrier structure. These effects collectively enhance the catalytic activity, stability and conductivity of the catalyst. The role of nitrogen atom: due to the larger electronegativity of nitrogen atom than carbon atom (electronegativity: nitrogen = 0.34; carbon = 2.55), part of the nitrogen atoms in the material make the adjacent carbon atoms positively charged, which is beneficial to the adsorption of oxygen and ensures the progress of the oxygen reduction reaction. Another part of the nitrogen atoms form M-Nx coordination structure with high-entropy atoms. Interestingly, during the OER reaction, surface reconstruction and lattice oxygen oxidation occur. High-entropy single atoms can effectively activate LOM through synergistic multi-path electron transfer, thereby showing excellent OER catalytic activity.

[0067] In summary, on the one hand, there are FeCrNiCoMn high-entropy single atoms in the catalyst, and they have good dispersity. Due to the driving effect between multiple elements in the high-entropy system, the free energy can be reduced, the grain growth and agglomeration can be inhibited, the thermal stability of metal atoms can be significantly improved, and the multi-atom anchoring mechanism makes single atoms more easily and stably dispersed in N-doped carriers, avoiding the formation of metal clusters or nanoparticles during the heat treatment process. Different atoms can provide diversified adsorption energy, making the catalyst suitable for multiple reaction paths. On the other hand, due to the surface reconstruction and lattice oxygen oxidation phenomenon during the OER process, it has excellent ORR activity and excellent OER performance. At the same time, the high-entropy metal combination can significantly improve the chemical stability and electrochemical corrosion resistance.

[0068] Those skilled in the art will readily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing FeCrNiCoMn high entropy single-atom nitrogen-doped carbon-based electrocatalyst, characterized in that: The following steps are involved: Step 1, mixing and dissolving a nitrogen-containing organic ligand and a zinc salt in a solvent; Step 2, dissolving iron salt, chromium salt, nickel salt, cobalt salt, and manganese salt in a solvent, then mixing with the solution of step 1, and stirring until the solvent evaporates and the mixture becomes sticky; Step 3, subjecting the viscous product of step 2 to a first heat treatment to obtain a powdery precursor; Step 4: subjecting the powdered precursor to a second heat treatment under an inert atmosphere to obtain a FeCrNiCoMn high-entropy single-atom nitrogen-doped carbon-based electrocatalyst.

2. The preparation method according to claim 1, characterized in that In step 1, the nitrogen-containing organic ligand is dimethylimidazole or diethylimidazole, and the zinc salt is one or more of zinc nitrate, zinc chloride or zinc acetate.

3. The preparation method according to claim 1, characterized in that In step 1, the mass ratio of the zinc salt to the nitrogen-containing organic ligand is greater than 0 and less than 3.

2.

4. The preparation method according to claim 1, characterized in that In step 2, the molar ratio of iron salt, chromium salt, nickel salt, cobalt salt and manganese salt is (0-1):(0-1):(0-1):(0-1):(0-1), preferably (0.6-0.8):(0.2-0.4):(0.1-0.3):(0.1-0.3):(0.1-0.3).

5. The preparation method according to claim 1, characterized in that In step 2, the iron salt, chromium salt, nickel salt, cobalt salt, and manganese salt are independently selected from one or more of nitrate, chloride, acetate, and acetylacetonate; and the solvent in steps 1 and 2 is water, methanol, acetone, or ethanol.

6. The preparation method according to claim 1, characterized in that In step 2, the stirring time is 3-12 hours.

7. The preparation method according to claim 1, characterized in that In step 3, the temperature of the first heat treatment is 150-200° C., and the holding time is 0.5-2 h.

8. The preparation method according to claim 1, characterized in that In step 4, the second heat treatment is performed at a heating rate of 2.5-7.5°C / min, an end point temperature of 900-1000°C, and a holding time of 1-5h; after calcination, the temperature is lowered to room temperature at a cooling rate of 2.5-7.5°C / min.

9. A FeCrNiCoMn high-entropy single-atom nitrogen-doped carbon-based electrocatalyst obtained by the preparation method according to any one of claims 1 to 8.

10. An application of the FeCrNiCoMn high-entropy single-atom nitrogen-doped carbon-based electrocatalyst according to claim 9 in hydrogen fuel cells, metal-air batteries, water electrolysis, air purification, wastewater treatment, and storage and conversion of renewable energy.

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