A carbon-supported nickel single-atom catalyst and its preparation method and application

Abstract

The present invention discloses a carbon-supported nickel single-atom catalyst and a preparation method and application thereof. The preparation method comprises the following steps: (1) reacting a raw material liquid to obtain a mixed liquid; the raw material liquid comprises carbon nanotubes, a nickel source, a nitrogen source and a solvent; (2) removing the solvent from the mixed liquid to obtain a solid; (3) heat-treating the solid under an inert gas to obtain a precursor; (4) acid-treating the precursor to obtain a carbon-supported nickel single-atom catalyst. In the carbon-supported nickel single-atom catalyst provided by the present invention, the nickel single atom has a super-coordinated structure, and the nickel single atom is monodispersed on the surface of the carbon nanotube. In the electrocatalytic two-electron oxygen reduction reaction to prepare hydrogen peroxide, it exhibits excellent Faraday efficiency of hydrogen peroxide and good stability at high current density.

Description

Technical Field

[0001] The invention relates to a carbon-supported nickel single-atom catalyst and a preparation method and application thereof. Background Art

[0002] Hydrogen peroxide (H 2 O 2 ) has been widely used as an environmentally friendly oxidant and potential energy carrier. The current industrial production of hydrogen peroxide involves the hazardous transportation of hydrogen peroxide and the additional use of hydrogen, which is usually centralized and energy intensive, limiting its implementation in remote areas. Electrochemical synthesis via a two-electron transfer oxygen reduction reaction pathway provides a promising alternative solution for small-scale on-site generation of hydrogen peroxide. However, the current electrochemical synthesis of hydrogen peroxide uses precious metal catalysts that work in acidic or alkaline electrolytes, resulting in high costs and environmental issues. Therefore, an increasing number of non-precious metal (e.g., nickel) electrocatalysts have attracted interest, some of which have shown satisfactory activity.

[0003] Among them, carbon-supported metal single atom catalysts (SACs) have become a hot new approach for the development of double electron transfer oxygen reduction reaction catalysts in recent years. 4 However, in order to achieve a high Faradaic current efficiency greater than 90%, the operating current density is limited to a low level (less than 100 mA cm -2 ). This motivated us to search for a way to further tune the coordination structure of metal single-atom catalysts to achieve high activity and Faradaic efficiency at high current density. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the defect that non-precious metal single-atom catalysts in the prior art cannot have high current density, high hydrogen peroxide Faraday efficiency and high catalytic activity in the process of electrocatalytic two-electron transfer oxygen reduction reaction, and provide a carbon-supported nickel single-atom catalyst and its preparation method and application. In the carbon-supported nickel single-atom catalyst provided by the present invention, the nickel single atom has a super-coordinated structure, and the nickel single atom is monodispersed on the surface of the carbon nanotube. In the electrocatalytic two-electron oxygen reduction reaction to prepare hydrogen peroxide, it shows excellent Faraday efficiency of hydrogen peroxide and good stability at high current density.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] The present invention provides a method for preparing a carbon-supported nickel single-atom catalyst, which comprises the following steps:

[0007] (1) reacting a raw material solution to obtain a mixed solution; the raw material solution comprises carbon nanotubes, a nickel source, a nitrogen source and a solvent;

[0008] (2) removing the solvent in the mixed solution to obtain a solid;

[0009] (3) heat treating the solid under an inert gas to obtain a precursor;

[0010] (4) Treating the precursor with acid to obtain a carbon-supported nickel single atom catalyst.

[0011] In the present invention, the nickel source may be a nickel source conventionally used in the art, generally having NiN 4 A structured nickel source, such as nickel phthalocyanine and / or nickel porphyrin.

[0012] In the present invention, the nitrogen source may be a nitrogen source conventionally used in the art, generally one or more of dicyandiamide, cysteine, glutamic acid, lysine, melamine, ethylenediamine, urea, aniline or polyethyleneimine, preferably melamine.

[0013] In the present invention, the carbon nanotubes may be carbon nanotubes commonly used in the art, preferably multi-walled carbon nanotubes or single-walled carbon nanotubes.

[0014] In the present invention, the carbon nanotubes are preferably carboxyl carbon nanotubes, and more preferably carboxyl multi-walled carbon nanotubes.

[0015] In step (1), the amount of the carbon nanotubes used can be the conventional amount in the art, generally 100 to 300 g.

[0016] In step (1), the molar ratio of the nickel source to the nitrogen source may be 1:(6.5×10 5 ~13×10 5 ), preferably 1:(8×10 5 ~12×10 5 ), for example 1:(10×10 5 ).

[0017] In step (1), the mass of the nickel source corresponding to the carbon nanotubes may be 1×10 5 ~5×10 5 g / mol, preferably 3×10 5 g / mol.

[0018] In step (1), the raw material solution can be prepared by conventional methods in the art by mixing the carbon nanotubes, the nickel source, the nitrogen source and the solvent.

[0019] Preferably, the method for preparing the raw material solution comprises: firstly dispersing the carbon nanotubes and the nitrogen source in a solvent, and then adding the nickel source and mixing.

[0020] The dispersion process is preferably carried out under ultrasonic conditions; wherein the frequency of the ultrasound is preferably 10 to 50 KHz, such as 40 KHz; and the time of the ultrasound is preferably 0.5 to 1 h, such as 0.8 h.

[0021] The mixing method is preferably stirring.

[0022] In step (1), the reaction time is 24 to 48 hours, for example 36 hours.

[0023] In step (1), the reaction temperature is 20-30°C, for example 25°C.

[0024] In step (1), the reaction is carried out under stirring, and the stirring rate is preferably 700-1200 rpm / min.

[0025] In step (1), the solvent can be any conventional solvent in the art that can disperse the carbon nanotubes and the nitrogen source, and is preferably a mixture of water and ethanol; more preferably, the volume ratio of water to ethanol in the mixture of water and ethanol is 1:1.

[0026] In step (2), the method for removing the solvent in the mixed solution includes centrifugation and drying.

[0027] Wherein, the centrifugal speed may be 8000-10000 r / min, for example 10000 r / min.

[0028] The drying temperature may be 50-80°C, such as 60°C or 70°C.

[0029] Wherein, the drying pressure may be 1-10Pa.

[0030] The drying time may be 20 to 24 hours, for example 22 hours.

[0031] In step (3), the inert gas may be argon.

[0032] In step (3), the heating rate of the heat treatment may be 2 to 10°C / min, preferably 4 to 8°C / min, for example 5°C / min.

[0033] In step (3), the temperature of the heat treatment may be 800-1000° C., for example, 900° C. The heat treatment causes the solid obtained in step (2) to undergo thermal decomposition and a coordination reaction to occur.

[0034] In step (3), the heat treatment time may be 0.5 to 1.5 h, for example 1 h.

[0035] In step (4), the acid used in the acid treatment is an inorganic strong acid, preferably one or more of sulfuric acid, hydrochloric acid and nitric acid. The nickel element in the precursor can be removed during the acid treatment to ensure that there are only single nickel atoms in the carbon-supported nickel single atom catalyst.

[0036] Wherein, the concentration of the inorganic strong acid may be 0.5-1 mol / L, for example 0.7 mol / L.

[0037] In step (4), the temperature of the acid treatment may be 60-100°C, for example 80°C.

[0038] The present invention also provides a carbon-supported nickel single-atom catalyst prepared by the above preparation method.

[0039] The present invention also provides a carbon-supported nickel single-atom catalyst, which comprises a carbon nanotube and a nickel single-atom catalyst supported on the surface of the carbon nanotube, wherein the nickel single atom has N 4 -Ni 1 -O x The coordination structure of N 4 -Ni 1 -O x The range of X is 0.5-2.5; the mass content of the nickel single atom is 0.1-0.5%, and the percentage is the percentage of the total mass of the carbon-supported nickel single atom catalyst.

[0040] In the present invention, the N 4 -Ni 1 -O x X can be 1, 1.5 or 2.

[0041] In the present invention, the mass content of the nickel single atom may be 0.2%, 0.3% or 0.4%, where the percentage is the percentage of the total mass of the carbon-supported nickel single atom catalyst.

[0042] The present invention also provides an application of the carbon-supported nickel single-atom catalyst in a double electron transfer oxygen reduction reaction.

[0043] In the present invention, the application is preferably an application in preparing hydrogen peroxide by a double electron transfer oxygen reduction reaction.

[0044] The reagents and raw materials used in the present invention are commercially available.

[0045] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0046] The reagents and raw materials used in the present invention are commercially available.

[0047] The positive and progressive effects of the present invention are:

[0048] 1. The carbon-supported nickel single atom catalyst provided by the present invention and its preparation method can realize the nickel single atom (N 4 -Ni 1 -O x ). It has the characteristics of high utilization rate of non-precious metal single atoms and good stability; the obtained material is easy to use and is conducive to promotion and application in industrial production.

[0049] 2. The carbon-supported nickel single-atom catalyst provided by the present invention has good catalytic performance and achieves a higher Faraday efficiency of hydrogen peroxide at a high current density. It provides new ideas and methods for the design and synthesis of electrocatalytic materials, so that it can simultaneously achieve a higher Faraday efficiency of hydrogen peroxide and a higher catalytic activity at a high current density, thereby further enhancing the application prospects of nickel single-atom catalysts in the industrial preparation of hydrogen peroxide. In a preferred embodiment, the current density is 300 mA cm -2 The Faradaic efficiency of hydrogen peroxide exceeds 90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 N prepared in Example 1 4 -Ni 1 -O 2 Energy dispersive X-ray spectroscopy (EDX) elemental analysis of / OCNTs. Figure 1 a is N prepared in Example 1 4 -Ni 1 -O 2 High-resolution scanning transmission electron microscopy images of OCNTs. Figure 1 b is the element scan of C, Figure 1 c is the element scanning diagram of Ni, Figure 1 d is the element scan of N.

[0051] Figure 2 N prepared in Example 1 4 -Ni 1 -O 2 Spherical aberration-corrected transmission electron microscopy image of / OCNTs material, with single nickel atoms indicated in the circle.

[0052] Figure 3 N prepared in Example 1 4 -Ni 1 -O 2 / OCNTs and N prepared in Example 2 4 -Ni 1 -O1 / MCNTs and Fourier transform spectra of Ni K-edge EXAFS spectra of NiPc in comparative example 2.

[0053] Figure 4 N prepared in Example 1 4 -Ni 1 -O 2 Fourier transform fitting spectrum of Ni K-edge EXAFS spectrum of / OCNTs.

[0054] Figure 5 The Faradaic efficiency of hydrogen peroxide of the catalysts prepared in Examples 1-2 and Comparative Examples 1-2 at different current densities.

[0055] Figure 6 N prepared in Example 1 4 -Ni 1 -O 2 / OCNTs stability test diagram for preparing hydrogen peroxide by electrocatalytic two-electron oxygen reduction. DETAILED DESCRIPTION

[0056] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0057] Example 1

[0058] Step (1): 200 mg of carboxyl purified multi-walled carbon nanotubes and 500 mg of melamine are dispersed in 120 mL of a mixed solvent of water and ethanol, wherein the volume ratio of water to ethanol is 1:1. Then ultrasonic treatment is performed for 0.5 hours at a frequency of 40 KHz. Then, 140 μL of a 25 mg / mL NiPc ethanol solution is added dropwise to the above solution under stirring, and the reaction is stirred at 25° C. for 24 hours to obtain a mixed solution;

[0059] Step (2): centrifuging the mixed solution obtained in step (1) at a rate of 1000 r / min, and drying the solid after centrifugation at a temperature of 80° C. for 24 h;

[0060] Step (3): grinding the black solid obtained in step (2), and then heat treating it at 1000° C. for 1 h at a heating rate of 5° C. / min in an Ar atmosphere;

[0061] Step (4): The heat-treated sample was treated in 0.5 mol / L sulfuric acid at 80°C for 12 h, washed with deionized water until neutral, and then dried at 80°C for 12 h to obtain N 4 -Ni1 -O 2 / OCNTs super-coordinated single atom catalyst.

[0062] Example 2

[0063] Step (1): 200 mg of multi-walled carbon nanotubes and 500 mg of melamine are dispersed in 120 mL of a mixed solvent of water and ethanol, wherein the volume ratio of water to ethanol is 1:1. Then, ultrasonic treatment is performed for 0.5 hours at a frequency of 40 KHz. Then, 140 μL of a 25 mg / mL NiPc ethanol solution is added dropwise to the above solution under stirring, and the reaction is stirred at 25° C. for 24 hours to obtain a mixed solution.

[0064] Step (2): centrifuging the mixed solution obtained in step (1) at a rate of 1000 r / min, and drying the solid after centrifugation at a temperature of 80° C. for 24 h;

[0065] Step (3): After grinding the black solid obtained in step (2), heat treatment was performed at 1000° C. in an Ar atmosphere at a heating rate of 5° C. / min for 1 h.

[0066] Step (4): The sample after heat treatment in step (3) was treated in 0.5 mol / L sulfuric acid at 80°C for 12 h, washed with deionized water until neutral, and then dried at 80°C for 12 h to obtain the N 4 -Ni 1 -O 1 Five-coordinated single atom catalyst, denoted as N 4 -Ni 1 -O 1 / MCNTs.

[0067] Example 3

[0068] Step (1): 200 mg of carboxyl purified multi-walled carbon nanotubes and 500 mg of melamine are dispersed in 120 mL of a mixed solvent of water and ethanol, wherein the volume ratio of water to ethanol is 1:1. Then ultrasonic treatment is performed for 0.5 hours at a frequency of 40 KHz. Then, 140 μL of a 25 mg / mL NiPc ethanol solution is added dropwise to the above solution under stirring, and the reaction is stirred at 25° C. for 24 hours to obtain a mixed solution;

[0069] Step (2): centrifuging the mixed solution obtained in step (1) at a rate of 1000 r / min, and drying the solid after centrifugation at a temperature of 80° C. for 24 h;

[0070] Step (3): grinding the black solid obtained in step (2), and then heat treating it at 1000° C. for 1 h at a heating rate of 2° C. / min under an Ar atmosphere;

[0071] Step (4): The heat-treated sample was treated in 0.5 mol / L sulfuric acid at 80°C for 12 h, washed with deionized water until neutral, and then dried at 80°C for 12 h to obtain N 4 -Ni 1 -O 2 / OCNTs super-coordinated single atom catalyst.

[0072] Comparative Example 1

[0073] Step (1): 200 mg of carboxyl purified multi-walled carbon nanotubes and 500 mg of melamine are dispersed in 120 ml of a mixed solvent of water and ethanol, wherein the volume ratio of water to ethanol is 1:1. Then, ultrasonic treatment is performed for 0.5 hours at a frequency of 40 KHz, and then stirred at room temperature for 24 hours to obtain a mixed solution.

[0074] Step (2): centrifuging the mixed solution obtained in step (1) at a rate of 1000 r / min, and drying the solid after centrifugation at a temperature of 80° C. for 24 h;

[0075] Step (3): After grinding the black solid obtained in step (2), heat-treat it at 1000° C. for 1 h at a heating rate of 5° C. / min in an Ar atmosphere to obtain carboxyl carbon nanotubes free of nickel source, which are referred to as OCNTs.

[0076] Comparative Example 2

[0077] Commercially available nickel phthalocyanine was used as a comparative example and was denoted as NiPc.

[0078] Effect Example 1

[0079] The N obtained in Example 1 4 -Ni 1 -O 2 / OCNTs nickel single atom catalysts were characterized by TEM, EDX elemental analysis and spherical aberration corrected transmission electron microscopy analysis. Figure 1 and Figure 2 It can be seen that N 4 -Ni 1 -O 2 The morphology of the nickel single atoms in the / OCNTs still maintains the morphology of the carboxyl carbon nanotubes, and energy dispersive X-ray spectroscopy (EDS) mapping confirms the uniform distribution of Ni, N, O, and C elements on the carboxyl carbon nanotubes. Spherical aberration-corrected scanning transmission electron microscopy images confirm that the Ni atoms are monodispersed on the surface of the carboxyl carbon nanotubes.

[0080] Effect Example 2

[0081] Figure 3 The Fourier transform spectra of Ni K-edge EXAFS spectra of the catalysts obtained in Examples 1, 2 and Comparative Example 2. Figure 3 It can be seen that the catalyst N 4 -Ni 1 -O 2 / OCNT and N 4 -Ni 1 -O 1 There is a peak corresponding to the Ni-N / O bond in / MCNT, but no peak corresponding to the Ni-Ni bond in the Ni Foil or the Ni-O bond in NiO. These results indicate that N 4 -Ni 1 -O 2 / OCNT and N 4 -Ni 1 -O 1 / Ni in MCNT exists in single atom form. NiO and Ni Foil are commercial products purchased.

[0082] Figure 4 is the Fourier transform fitting spectrum of the Ni K-edge EXAFS spectrum of the catalyst obtained in Example 1, from Figure 4 It can be concluded that the structure of the nickel single atom site is N 4 -Ni 1 -O 2 .

[0083] Effect Example 3

[0084] Electrocatalytic two-electron oxygen reduction performance test

[0085] Test method: (1) 10 mg of the catalyst obtained in Example 1 was mixed with 0.96 mL of ethanol and 0.04 mL of 5 wt% Nafion 117 solution to obtain a catalyst dispersion; the catalyst dispersion was then added dropwise to a gas diffusion electrode and dried in air to obtain a catalyst loading of 0.1 mg / cm 2 N 4 -Ni 1 -O 2 / OCNT working electrode;

[0086] (2) The above load N 4 -Ni 1 -O 2 The gas diffusion electrode of / OCNT, porous nickel foam and saturated Ag / AgCl electrode were used as cathode, anode and reference electrode, respectively, for the tests.

[0087] During the entire test, the oxygen flow rate was kept constant at 50 mL min -1 The rate of is passed into the electrolytic cell, and 1 mol / L KOH electrolyte circulates at the anode and cathode of the electrolytic cell respectively.

[0088] When testing the linear sweep voltammetry curve, the electrochemical workstation was set at 5 mV s -1 The data were collected at a scanning rate of , and the results are shown in Table 1. It can be seen that: N 4 -Ni 1 -O 2 / OCNT as a gas diffusion electrode, showed great catalytic activity, N 4 -Ni 1 -O 2 / OCNTs achieve 350mA cm at 0.65V -2 The maximum current density is greater than that of Example 2 (98.47 mA cm -2 ), and is much larger than that of comparative example 1 (74.6 mA cm -2 ) and Comparative Example 2 (48.3 mA cm -2 ) to prepare the obtained electrode.

[0089] Table 1

[0090]

[0091]

[0092] Effect Example 4

[0093] Example 1 obtained N 4 -Ni 1 -O 2 / OCNTs catalysts in the range of 100 to 350 mA cm -2 Constant current electrolysis was carried out at different current densities to test the Faraday efficiency of the product hydrogen peroxide. The concentration of hydrogen peroxide was measured by cerium sulfate titration.

[0094] Figure 5 The Faraday efficiency of hydrogen peroxide of the catalysts prepared in Examples 1 to 2 and Comparative Examples 1 to 2 at different current densities. Figure 5 As can be seen from Table 2, the N obtained in Example 1 4 -Ni 1 -O 2 / OCNTs catalysts in the range of 100 to 350 mA·cm -2 The Faradaic efficiency of hydrogen peroxide is better than 86% in the wide application current range of 100 and 200 mA cm -2 The maximum hydrogen peroxide Faradaic efficiency is over 96%.-2 In a wide range of applied current, the hydrogen peroxide Faraday efficiency of the catalyst prepared in Example 1 is higher than that of the catalysts in Comparative Examples 1 and 2.

[0095] Table 2

[0096]

[0097] Effect Example 5

[0098] Figure 6 N prepared in Example 1 4 -Ni 1 -O 2 Stability test of the nickel single-atom catalyst of / OCNTs as an electrocatalytic two-electron oxygen reduction to prepare hydrogen peroxide. The test conditions are a high current of 200 mA cm -2 It can be seen that when the overpotential is stable at 0.3V (without resistance compensation) during the test, the Faradaic efficiency of preparing hydrogen peroxide is maintained at more than 80%. At the same time, the Faradaic efficiency of hydrogen peroxide does not show a significant decrease after 24 hours of reaction, indicating that it has very good stability.

[0099] Effect Example 6

[0100] The heating rate in step (3) of Example 1 was changed to obtain Example 3, whose performance of electrocatalytic two-electron oxygen reduction to prepare hydrogen peroxide was slightly worse than that of the nickel single atom catalyst obtained in Examples 1 and 2, but better than that of the four-coordinated Ni-N represented by NiPc in Comparative Examples 1 and 2. 4 Faradaic efficiency performance of coordinated hydrogen peroxide.

Claims

1. A method for preparing a carbon-supported nickel single-atom catalyst, It is characterized in that It includes the following steps: (1) reacting a raw material solution to obtain a mixed solution; the raw material solution comprises carbon nanotubes, a nickel source, a nitrogen source and a solvent; Wherein, the nickel source is NiN 4 The nickel source of the structure, the carbon nanotubes are carboxyl multi-walled carbon nanotubes; (2) removing the solvent in the mixed solution to obtain a solid; (3) heat treating the solid under an inert gas to obtain a precursor; (4) Treating the precursor with acid to obtain a carbon-supported nickel single atom catalyst.

2. The method for preparing the carbon-supported nickel single-atom catalyst according to claim 1, It is characterized in that In step (1), the nickel source is nickel phthalocyanine and / or nickel porphyrin; And / or, in step (1), the nitrogen source is one or more of dicyandiamide, cysteine, glutamic acid, lysine, melamine, ethylenediamine, urea, aniline or polyethyleneimine; And / or, in step (1), the solvent is a mixture of water and ethanol; And / or, in step (1), the amount of the carbon nanotubes is 100 to 300 g; And / or, in step (1), the molar ratio of the nickel source to the nitrogen source is 1:(6.5×10 5 ~13×10 5 ); And / or, in step (1), the mass of the nickel source corresponding to the carbon nanotubes is 1×10 5 ~5×10 5 g / mol.

3. The method for preparing the carbon-supported nickel single-atom catalyst according to claim 2, It is characterized in that In step (1), the nitrogen source is melamine; And / or, in step (1), the volume ratio of water to ethanol in the water-ethanol mixture is 1:1; And / or, in step (1), the molar ratio of the nickel source to the nitrogen source is 1:(8×10 5 ~12×10 5 ); And / or, in step (1), the mass of the nickel source corresponding to the carbon nanotubes is 3×10 5 g / mol.

4. The method for preparing the carbon-supported nickel single-atom catalyst according to claim 3, It is characterized in that In step (1), the molar ratio of the nickel source to the nitrogen source is 1:(10×10 5 ).

5. The method for preparing the carbon-supported nickel single-atom catalyst according to claim 1, It is characterized in that In step (1), the method for preparing the raw material solution comprises: firstly dispersing the carbon nanotubes and the nitrogen source in a solvent, and then adding the nickel source and mixing.

6. The method for preparing the carbon-supported nickel single-atom catalyst according to claim 5, It is characterized in that In step (1), the dispersion process is carried out under ultrasonic conditions; And / or, in step (1), the mixing method is stirring.

7. The method for preparing the carbon-supported nickel single-atom catalyst according to claim 6, It is characterized in that In step (1), the frequency of the ultrasound is 10 to 50 KHz; And / or, in step (1), the ultrasonic time is 0.5 to 1 h.

8. The method for preparing the carbon-supported nickel single-atom catalyst according to claim 7, It is characterized in that In step (1), the frequency of the ultrasound is 40 KHz; And / or, in step (1), the ultrasonic time is 0.8h.

9. The method for preparing the carbon-supported nickel single-atom catalyst according to claim 1, It is characterized in that In step (1), the reaction time is 24 to 48 hours; And / or, in step (1), the reaction temperature is 20 to 30°C; And / or, in step (1), the reaction is carried out under stirring.

10. The method for preparing the carbon-supported nickel single-atom catalyst according to claim 9, It is characterized in that In step (1), the reaction time is 36 hours; And / or, in step (1), the reaction temperature is 25°C; And / or, in step (1), the stirring rate is 700-1200 rpm / min.

11. The method for preparing the carbon-supported nickel single-atom catalyst according to claim 1, It is characterized in that In step (2), the method for removing the solvent in the mixed solution includes centrifugation and drying.

12. The method for preparing the carbon-supported nickel single-atom catalyst according to claim 11, It is characterized in that In step (2), the centrifugal speed is 8000-10000 r / min; And / or, in step (2), the drying temperature is 50 to 80°C; And / or, in step (2), the drying pressure is 1 to 10 Pa; And / or, in step (2), the drying time is 20 to 24 hours.

13. The method for preparing the carbon-supported nickel single-atom catalyst according to claim 12, It is characterized in that In step (2), the centrifugal speed is 10000 r / min; And / or, in step (2), the drying temperature is 60° C. or 70° C.; And / or, in step (2), the drying time is 22 hours.

14. The method for preparing the carbon-supported nickel single-atom catalyst according to claim 1, It is characterized in that In step (3), the inert gas is argon; And / or, in step (3), the heating rate of the heat treatment is 2 to 10°C / min; And / or, in step (3), the temperature of the heat treatment is 800-1000°C; And / or, in step (3), the heat treatment time is 0.5 to 1.5 hours; And / or, in step (4), the acid used in the acid treatment is a strong inorganic acid; And / or, in step (4), the temperature of the acid treatment is 60-100°C.

15. The method for preparing the carbon-supported nickel single-atom catalyst according to claim 14, It is characterized in that In step (3), the heating rate of the heat treatment is 4 to 8°C / min; And / or, in step (3), the temperature of the heat treatment is 900°C; And / or, in step (3), the heat treatment time is 1 hour; And / or, in step (4), the acid used in the acid treatment is one or more of sulfuric acid, hydrochloric acid and nitric acid; And / or, in step (4), the concentration of the inorganic strong acid is 0.5 to 1 mol / L; And / or, in step (4), the temperature of the acid treatment is 80°C.

16. The method for preparing the carbon-supported nickel single-atom catalyst according to claim 15, It is characterized in that In step (3), the heating rate of the heat treatment is 5°C / min; And / or, in step (4), the concentration of the inorganic strong acid is 0.7 mol / L.

17. A carbon-supported nickel single atom catalyst, It is characterized in that It is prepared by the preparation method described in any one of claims 1 to 16.

18. A carbon-supported nickel single atom catalyst, It is characterized in that The invention comprises a carbon nanotube and a nickel single atom catalyst supported on the surface of the carbon nanotube, wherein the nickel single atom has N 4 -Ni 1 -O x The coordination structure of N 4 -Ni 1 -O x The range of X in the middle is 1.5 to 2.5; The mass content of the nickel single atom is 0.1-0.5%, where the percentage is the percentage of the total mass of the carbon-supported nickel single atom catalyst.

19. The carbon-supported nickel single-atom catalyst according to claim 18, It is characterized in that The N 4 -Ni 1 -O x In the example, X is 2; And / or, the mass content of the nickel single atom is 0.2%, 0.3% or 0.4%, where the percentage is the percentage of the total mass of the carbon-supported nickel single atom catalyst.

20. Use of the carbon-supported nickel single-atom catalyst according to any one of claims 17 to 19 in a two-electron transfer oxygen reduction reaction.

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