Zinc-air battery catalyst and method of preparation

Abstract

The application provides a zinc-air battery catalyst and a preparation method, a structural unit of which is a nitrogen-doped carbon nanotube as a conductive network, and a nitrogen-doped cobalt-iron selenide nanosheet is loaded thereon. The preparation method comprises the following steps: hollow polypyrrole nanotubes are synthesized and subjected to dielectric barrier discharge surface modification treatment, so that cobalt ions and TCPP(Fe) are effectively adsorbed, and growth of Co-TCPP(Fe) nanosheets on the surface is realized; the cobalt ions, the iron porphyrin and the polypyrrole nanotubes are mixed in a solution to generate a Co-TCPP(Fe)@p-PPy composite material; the Co-TCPP(Fe)@p-PPy composite material is subjected to high-temperature calcination to obtain CoFe@NC@NCNTs, and finally, selenization treatment is performed to obtain N-CoFeSe2@NC@NCNTs. In the catalysis of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) of the zinc-air battery, the catalyst can significantly improve the surface activity and conductivity of the catalyst, exhibits excellent OER and ORR performance, and meets the requirements of commercial application.

Description

Technical Field

[0001] This invention belongs to the field of zinc-air battery catalyst technology, specifically relating to a zinc-air battery catalyst and its preparation method. Background Technology

[0002] With economic development, the overuse of fossil fuels has led to their depletion and a series of pollution problems. The development of new clean energy sources can effectively alleviate these issues. Among these, secondary batteries, represented by lithium-ion batteries, have been widely used as energy storage devices. However, due to inherent safety concerns and the limited reserves of lithium metal, the large-scale use of lithium metal will inevitably lead to a shortage of lithium salts. Zinc-air batteries, with their high energy density, excellent durability, and clean, pollution-free operation, can effectively solve the problems associated with lithium batteries. However, the slow multi-step electron transfer kinetics of oxygen during the charging and discharging process of rechargeable zinc-air batteries result in low round-trip energy efficiency, severely restricting the development of rechargeable ZABs.

[0003] Rechargeable zinc-air batteries convert chemical energy into electrical energy through redox reactions between an air electrode and oxygen. The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are two key steps, but their kinetics are very slow, necessitating the design of highly efficient bifunctional catalysts. Currently, Pt-based catalysts are the best ORR catalysts, but Pt exhibits poor OER activity. RuO2 and lrO2 are better OER catalysts, but their ORR performance is poor. While combining these two catalysts can achieve bifunctional catalysis, it also leads to complex processes and high costs. Therefore, there is an urgent need to design a highly efficient bifunctional catalyst for rechargeable zinc-air batteries.

[0004] In recent years, single-atom catalysts (SACs) with maximum atom utilization efficiency and high catalytic selectivity have shown significant advantages in the field of catalysis. Numerous experimental and theoretical studies have demonstrated that atomically dispersed transition metal-nitrogen-carbon (MNC) groups exhibit high catalytic activity and selectivity for ORR (Organic Response), with ORR performance comparable to current Pt-based materials. Co-NC, in particular, shows a clear advantage in catalytic activity. However, high metal atom loading, due to the high surface energy of metal atoms, tends to aggregate, which is detrimental to improving catalytic performance. Metal-organic frameworks (MOFs), with their unique porous structure and high specific surface area, are beneficial for dispersing metal atoms and improving catalytic activity. Furthermore, using MOFs as precursors, during high-temperature calcination, nitrogen-containing ligands are transformed into negatively charged nitrogen-doped groups in the carbon substrate to coordinate and stabilize the target positively charged metal atoms. Therefore, some MOFs with high metal-nitrogen coordination content have been widely used in the synthesis of SACs. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a zinc-air battery catalyst and its preparation method, which features high specific surface area, numerous active sites, and excellent electrochemical performance.

[0006] A zinc-air battery catalyst is obtained by using nitrogen-doped carbon nanotubes as a conductive network and loading cobalt-iron alloy nitrogen-doped carbon nanosheets onto the conductive carbon network, thereby obtaining a nitrogen-doped cobalt-iron selenide (N-CoFeSe2@NC@NCNTs) grown on the nitrogen-doped carbon nanotube network as a zinc-air battery catalyst.

[0007] A method for preparing a zinc-air battery catalyst specifically includes the following steps:

[0008] (1) Preparation of polypyrrole nanotubes (PPy NTs): Polypyrrole nanotubes, namely PPy NTs, were prepared by dissolving ferric chloride hexahydrate (FeCl3·6H2O), methyl orange (MO) and pyrrole monomer.

[0009] (2) Surface treatment of polypyrrole nanotubes (p-PPy NTs): The surface-treated polypyrrole nanotubes, namely p-PPy, are obtained by surface treatment of polypyrrole nanotubes with surfactant and dielectric barrier discharge.

[0010] (3) Preparation of Co-TCPP(Fe)@p-PPy composite material: Cobalt salt, pyrazine, PVP and p-PPy are mixed, and TCPP(Fe) dissolved in DMF and ethanol solution is added dropwise. Cobalt-based organic framework nanosheets prepared by hydrothermal method are uniformly grown on polypyrrole nanotubes, which is the Co-TCPP(Fe)@p-PPy composite material.

[0011] (4) Synthesis of CoFe@NC@NCNTs: Co-TCPP(Fe)@p-PPy composite material was carbonized and reduced in an inert gas atmosphere. After cooling, the nitrogen-doped carbon nanotube-supported cobalt-iron alloy nitrogen-doped carbon nanosheets were collected and named CoFe@NC@NCNTs.

[0012] (5) Synthesis of N-CoFeSe2@NC@NCNTs: Using CoFe@NC@NCNTs as a precursor, selenium powder was placed upstream of a tube furnace and subjected to selenization and nitridation under an Ar / NH3 radio frequency plasma atmosphere. After cooling, nitrogen-doped cobalt iron selenide loaded with nitrogen-doped carbon nanotubes was obtained and named N-CoFeSe2@NC@NCNTs.

[0013] Preferably, in step one, the molar ratio of MO to FeCl3·6H2O is 1:10-1:15, the concentration of the MO solution is 3mmol / L-6mmol / L, and the molar ratio of FeCl3·6H2O to pyrrole is 1:1.5-1:2.5.

[0014] Preferably, in step (1), the surfactant is sodium dodecyl sulfonate, and the mass ratio of sodium dodecyl sulfonate to polypyrrole nanotubes is 1:0.5-1:1.5.

[0015] Preferably, in step (2), the dielectric barrier discharge processing conditions are a voltage of 70-80V, a current of 50-100mA, and a processing time of 2-10min.

[0016] Preferably, in step (3), the molar ratio of cobalt salt to pyrazine is 1:1-2:1, the Co ion concentration is 1 mmol / L-1.5 mmol / L, the molar ratio of cobalt salt to TCPP(Fe) is 5:1-1:1, and the amount of PVP is 1.5 g / L-2 g / L. The described reaction temperature is 75-95℃, and the reaction time is 18-32 h.

[0017] As a preferred option, in step (4), the specific operation method is to heat the furnace from room temperature to 300-400℃ in an inert gas atmosphere for a period of time at a heating rate of 3-6℃ / min, maintain this temperature for 1-3 hours, then heat the furnace to 700-900℃, maintain this temperature for 1-3 hours, cool the furnace, wash the black powder obtained with HCl aqueous solution, water, and ethanol, collect the black powder by centrifugation, and dry it in an oven at 60℃ to obtain a sample named CoFe@NC@NCNTs.

[0018] Preferably, in step (4), the inert gas is generally one or both of Ar or N2.

[0019] Preferably, in step (5), under an Ar / NH3 atmosphere, the temperature is increased from room temperature to 300-400℃ at a rate of 3-6℃ / min, and radio frequency plasma discharge treatment is performed. The discharge power is 50-150W, the gas pressure is 10-30Pa, and the radio frequency plasma discharge treatment is performed at this temperature for 1-3 hours, simultaneously achieving selenization and nitridation treatments. The amount of selenium powder is 10-20mmol, and the resulting sample is named N-CoFeSe2@NC@NCNTs. The beneficial effects of this invention are:

[0020] 1. At potentials below 0.6V, the N-CoFeSe2@NC@NCNTs sample exhibits a higher limiting current density than commercial Pt / C catalysts, and this material has faster reaction kinetics in ORR electrocatalysis.

[0021] 2. At a current density of 10 mA cm⁻¹ -2 At that time, the OER overpotential was only 339.5 mV. Under the same test conditions, the overpotential of the commercial RuO2 catalyst was 453.5 mV, indicating that the N-CoFeSe2@NC@NCNTs sample prepared in this invention exhibits excellent OER catalytic activity. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0023] Figure 1 The microstructure of N-CoFeSe2@NC@NCNTs prepared in Example 1 is shown under a scanning electron microscope.

[0024] Figure 2 Linear sweep voltammetry (LSV) plots of oxygen reduction reaction (ORR) for Example 1, Comparative Example 1, and the comparative sample.

[0025] Figure 3 Linear sweep voltammetry (LSV) plots of the oxygen evolution reaction (OER) for Example 1, Comparative Example 1, and the comparative sample. Detailed Implementation

[0026] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a method for preparing a nitrogen-doped cobalt iron selenide catalyst (N-CoFeSe2@NC@NCNTs) grown on a nitrogen-doped carbon nanotube network and its beneficial effects in zinc-air batteries. The examples in this specification are merely illustrative and not intended to limit the invention. The parameters, proportions, etc., in the examples are selected according to actual conditions and have no substantial impact on the results.

[0027] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0028] Example 1:

[0029] The preparation of nitrogen-doped carbon nanotube-supported nitrogen-doped cobalt iron selenide nanosheets (N-CoFeSe2@NC@NCNTs) includes the following steps:

[0030] (1) Preparation of polypyrrole nanotubes (PPy NTs): 3.893 g of FeCl3·6H2O was dissolved in 240 mL of 5 mmol / L MO (methyl orange) aqueous solution. Then 1.2 mL of pyrrole monomer was added, and the mixture was magnetically stirred at room temperature for 24 h. After the reaction was completed, the solution was filtered and washed with anhydrous ethanol and ultrapure water until it was colorless. The solid was then obtained by centrifugation and dried in an oven at 60 °C for 5 h to obtain polypyrrole nanotubes, which were labeled as PPy NTs.

[0031] (2) Dielectric barrier discharge surface treatment of polypyrrole nanotubes (PPy NTs): Weigh the mass of PPy NTs, then weigh out half the mass of sodium dodecyl sulfate and dissolve it in ultrapure water. Then add PPy NTs and methanol to the above solution. Disperse the mixture with ultrasound for 3 hours. After uniform dispersion, centrifuge the mixture and collect the lower precipitate. Then centrifuge the precipitate three times with methanol and collect the lower precipitate. Then dry it in an oven at 60℃ for 5 hours to obtain the product, called S-PPy. Treat S-PPy with dielectric barrier discharge plasma at 75V and 55W for 5 minutes. The resulting sample is recorded as p-PPy.

[0032] (3) Preparation of Co-TCPP(Fe)@p-PPy composite material: 0.0873 g of Co(NO3)2·6H2O, 0.016 g of pyrazine, 0.4 g of PVP, and 0.025 g of p-PPy were dissolved in 240 mL of DMF and ethanol (V DMF :V 乙醇 A mixture of 3:1 (e.g., 0.1 mmol of TCPP(Fe)) was placed in a 500 mL round-bottom flask and labeled as solution A. Then, 0.1 mmol of TCPP(Fe) was dissolved in 80 mL of DMF and ethanol (V / L). DMF :V 乙醇 In a mixture of solutions A and B (ratio 3:1), denoted as solution B, solution B was added dropwise to solution A with stirring. The solution in the round-bottom flask was then sonicated at room temperature for 10 minutes. After thorough mixing, the round-bottom flask was heated to 80°C and the reaction was maintained for 24 hours. After cooling, the mixture was centrifuged, washed twice with ethanol, and dried in an oven at 60°C to obtain the Co-TCPP(Fe)@p-PPy composite material.

[0033] (4) Synthesis of CoFe@NC@NCNTs: Co-TCPP(Fe)@p-PPy was carbonized using a conventional quartz tube furnace. 300 mg of dried Co-TCPP(Fe)@p-PPy was uniformly distributed on the bottom of a ceramic boat and heated from room temperature to 300 °C within 1 hour under an Ar atmosphere. After holding at this temperature for 2 hours, the temperature was increased to 800 °C at a rate of 5 °C / min. This temperature was then maintained for another 2 hours. After cooling, the black powder was washed with HCl aqueous solution, water, and ethanol. The black powder was then dried in a 60 °C oven to obtain the sample, named CoFe@NC@NCNTs.

[0034] (5) Synthesis of N-CoFeSe2@NC@NCNTs: CoFe@NC@NCNTs were placed in a tube furnace, with 15.0 mmol of selenium powder upstream of the CoFe@NC@NCNTs precursor. Then, under an Ar / NH3 atmosphere, radio frequency plasma discharge treatment was performed at 350℃ with a heating rate of 5℃ / min, a discharge power of 100W, and a gas pressure of 20Pa. The radio frequency plasma discharge treatment was performed at this temperature for 2h, simultaneously achieving selenization and nitridation. The final sample was named N-CoFeSe2@NC@NCNTs.

[0035] Bifunctional catalytic performance evaluation:

[0036] The electrocatalytic performance of the prepared samples was tested using an electrochemical workstation (CHI760E) in a three-electrode configuration.

[0037] Preparation of working electrodes for ORR and OER performance testing: Before using the rotating disk electrode (RDE), the glassy carbon electrode (GCE, d = 4.0 mm) was polished to a mirror finish using a polishing cloth containing Al2O3 powder, then rinsed with distilled water and dried at room temperature. The powder sample needs to be prepared into a slurry and coated onto the glassy carbon electrode for testing. The slurry preparation method is as follows: Weigh 5 mg of the final powder sample obtained in Example 1 and add it to a mixed solution of 50 μL of 5% Nafion solution and 950 μL of isopropanol. Treat the mixture in an ultrasonic cleaner for 20 min to form a homogeneous slurry. Add 10 μL dropwise for testing.

[0038] As a control experiment, a commercial 20 wt.% Pt / C catalyst was selected for the ORR test, and the slurry preparation method was the same as that used for the powder sample prepared in Example 1. 5 mg of 20 wt.% Pt / C powder was prepared into a slurry and uniformly drop-coated onto the electrode for testing. A commercial RuO2 catalyst was selected for the OER test, and the slurry preparation method was the same as that used for the powder sample prepared in Example 1. 5 mg of RuO2 powder was prepared into a slurry and uniformly drop-coated onto the electrode for testing. Electrochemical performance testing: A standard three-electrode electrochemical testing system was used, with a Pt sheet electrode as the counter electrode, a saturated calomel electrode (SCE) as the reference electrode, and the working electrode prepared above. The test solution was a 0.1 M KOH solution (pH = 13). All potentials were calculated using the Nernst equation with reference to the reversible hydrogen electrode (RHE): E(RHE) = E(Hg / Hg2Cl2) + 0.2415 + 0.059pH. Before linear sweep voltammetry (LSV) testing, the working electrode was tested at 10 mV s. -1 The scan rate was activated by CV for 50 cycles, and all electrochemical tests were performed at room temperature.

[0039] The LSV curves of the ORR of the N-CoFeSe2@NC@NCNTs sample prepared in Example 1 and the commercial 20wt.% Pt / C catalyst in 0.1M KOH solution saturated with O2 were tested using a rotating disk electrode (RDE) at 1600 rpm. The results are as follows. Figure 2 As shown, the onset potential and half-wave potential of N-CoFeSe2@NC@NCNTs were 1.0845 V and 0.8245 V vs. RHE, respectively, and their electrocatalytic activity was similar to that of commercial Pt / C catalysts tested under the same conditions (onset potential and half-wave potential were 1.0965 V and 0.8655 V vs. RHE, respectively). Below 0.6 V, the N-CoFeSe2@NC@NCNTs samples exhibited a high limiting current density of 5.7093 mA cm⁻¹. -2 Higher than commercial Pt / C catalysts (4.88 mA cm⁻¹). -2 This indicates that the material exhibits rapid reaction kinetics during the ORR electrocatalysis process.

[0040] The OER catalytic activity was also tested under the exact same conditions as the ORR test, and the commercial RuO2 catalyst was also tested under the same conditions as a comparative reference. Figure 3 As shown, the N-CoFeSe2@NC@NCNTs sample prepared in Example 1 was subjected to a current density of 10 mA cm⁻¹. -2At that time, the OER overpotential was only 339.5 mV. Under the same test conditions, the overpotential of the commercial RuO2 catalyst was 453.5 mV, indicating that the N-CoFeSe2@NC@NCNTs sample prepared in Example 1 has excellent OER catalytic activity.

[0041] Comparative Example 1: Nitrogen-doped carbon nanotubes supporting cobalt-iron alloy nitrogen-doped carbon nanosheets (CoFe@NC@NCNTs)

[0042] (1) Preparation of polypyrrole nanotubes (PPy NTs): 3.893 g of FeCl3·6H2O was dissolved in 240 mL of 5 mmol / L MO (methyl orange) aqueous solution. Then 1.2 mL of pyrrole monomer was added, and the mixture was magnetically stirred at room temperature for 24 h. After the reaction was completed, the solution was filtered and washed with anhydrous ethanol and ultrapure water until it was colorless. The solid was then obtained by centrifugation and dried in an oven at 60 °C for 5 h to obtain polypyrrole nanotubes, which were labeled as PPy NTs.

[0043] (2) Dielectric barrier discharge surface treatment of polypyrrole nanotubes (PPy NTs): Weigh the mass of PPy NTs, then weigh out half the mass of sodium dodecyl sulfate and dissolve it in ultrapure water. Then add PPy NTs and methanol to the above solution. Disperse the mixture with ultrasound for 3 hours. After uniform dispersion, centrifuge the mixture and collect the lower precipitate. Then centrifuge the precipitate three times with methanol and collect the lower precipitate. Then dry it in an oven at 60℃ for 5 hours to obtain the final product, called S-PPy. Treat S-PPy with dielectric barrier discharge plasma at 75V and 55W for 5 minutes. The resulting sample is recorded as p-PPy.

[0044] (3) Preparation of Co-TCPP(Fe)@p-PPy composite material: Co(NO3)2·6H2O (0.0873 g), pyrazine (0.016 g), PVP (0.4 g), and 0.025 g p-PPy were dissolved in 240 mL of DMF and ethanol (V DMF :V 乙醇 A mixture of 3:1 (e.g., 0.1 mmol of TCPP(Fe)) was placed in a 500 mL round-bottom flask and labeled as solution A. Then, 0.1 mmol of TCPP(Fe) was dissolved in 80 mL of DMF and ethanol (V / L). DMF :V 乙醇 In a mixture of solutions A and B (ratio 3:1), denoted as solution B, solution B was added dropwise to solution A with stirring. The solution in the round-bottom flask was then sonicated at room temperature for 10 minutes. After thorough mixing, the round-bottom flask was heated to 80°C and the reaction was maintained for 24 hours. After cooling, the mixture was centrifuged, washed twice with ethanol, and dried in an oven at 60°C to obtain the Co-TCPP(Fe)@p-PPy composite material.

[0045] (4) Synthesis of CoFe@NC@NCNTs: Co-TCPP(Fe)@p-PPy was carbonized using a conventional quartz tube furnace. 300 mg of dried Co-TCPP(Fe)@p-PPy was uniformly distributed on the bottom of a ceramic boat and heated from room temperature to 300 °C within 1 hour under an Ar atmosphere. After holding at this temperature for 2 hours, the temperature was increased to 800 °C at a rate of 5 °C / min. This temperature was then maintained for another 2 hours. After cooling, the black powder was washed with HCl aqueous solution, water, and ethanol. The black powder was then dried in a 60 °C oven to obtain the sample, named CoFe@NC@NCNTs.

[0046] The LSV curve of the ORR of the CoFe@NC@NCNTs sample prepared in Comparative Example 1 in a 0.1M KOH solution saturated with O2 was tested using a rotating disk electrode (RDE) at a rotation speed of 1600 rpm. The results are as follows. Figure 2 As shown.

[0047] The CoFe@NC@NCNTs sample prepared in Comparative Example 1 exhibited high ORR electrocatalytic activity, with an onset potential of 1.0545 V and a half-wave potential of 0.8165 V vs. RHE. Its electrocatalytic activity was slightly lower than that of the N-CoFeSe2@NC@NCNTs catalyst prepared in Example 1 under the same conditions, but higher than that of the commercial Pt / C catalyst. The CoFe@NC@NCNTs sample showed a high limiting current density of 5.543 mA cm⁻¹. -2 It still exhibits excellent ORR catalytic activity.

[0048] The OER catalytic activity was also tested under the exact same conditions as the ORR test, such as... Figure 3 As shown, the CoFe@NC@NCNTs sample prepared in Comparative Example 1 was subjected to a current density of 10 mA cm⁻¹. -2 At this time, the OER overpotential is 387.5mV, exhibiting excellent OER catalytic activity.

[0049] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a zinc-air battery catalyst, characterized in that, The preparation method specifically includes the following steps: (1) Preparation of polypyrrole nanotubes: polypyrrole nanotubes, namely PPy NTs, were prepared by dissolving FeCl3·6H2O, methyl orange and pyrrole monomer; (2) Surface treatment of polypyrrole nanotubes: surface treatment of polypyrrole nanotubes with surfactant and dielectric barrier discharge is used to obtain surface-treated polypyrrole nanotubes, namely p-PPy; (3) Preparation of Co-TCPP(Fe)@p-PPy composite material: Cobalt salt, pyrazine, PVP and p-PPy are mixed, and TCPP(Fe) dissolved in DMF and ethanol solution is added dropwise. Cobalt-based organic framework nanosheets prepared by hydrothermal method are uniformly grown on polypyrrole nanotubes, i.e. Co-TCPP(Fe)@p-PPy composite material. The molar ratio of cobalt salt to pyrazine is 1:1-2:1, the molar ratio of cobalt salt to TCPP(Fe) is 5:1-1:1, the Co ion concentration is 1 mmol / L-1.5 mmol / L, the amount of PVP is 1.5 g / L-2 g / L, the reaction temperature is 75-95℃, and the reaction time is 18-32 h. (4) Synthesis of CoFe@NC@NCNTs: Co-TCPP(Fe)@p-PPy composite material was carbonized and reduced in an inert gas atmosphere. After cooling, the nitrogen-doped carbon nanotube-supported cobalt-iron alloy nitrogen-doped carbon nanosheets, namely CoFe@NC@NCNTs, were collected. (5) Synthesis of N-CoFeSe2@NC@NCNTs: Using CoFe@NC@NCNTs as a precursor, selenium powder was placed upstream of a tube furnace and heated from room temperature to 300-400℃ at a rate of 3-6℃ / min under an Ar / NH3 atmosphere. Radio frequency plasma discharge treatment was carried out with a discharge power of 50-150W and a gas pressure of 10-30Pa. Radio frequency plasma discharge treatment was carried out at this temperature for 1-3 h, and selenization and nitridation treatment were achieved simultaneously. The amount of selenium powder was 10-20 mmol, and N-CoFeSe2@NC@NCNTs were obtained.

2. The method for preparing a zinc-air battery catalyst according to claim 1, characterized in that, In step (1), the molar ratio of methyl orange to FeCl3·6H2O is 1:10-1:15, the concentration of the methyl orange solution is 3mmol / L-6mmol / L, and the molar ratio of FeCl3·6H2O to pyrrole is 1:1.5-1:2.

5.

3. The method for preparing a zinc-air battery catalyst according to claim 1, characterized in that, In step (2), the surfactant is sodium dodecyl sulfonate, and the mass ratio of sodium dodecyl sulfonate to polypyrrole nanotubes is 1:0.5-1:1.

5.

4. The method for preparing a zinc-air battery catalyst according to claim 1, characterized in that, In step (2), the dielectric barrier discharge processing conditions are a voltage of 70-80 V, a current of 50-100 mA, and a processing time of 2-10 min.

5. The method for preparing a zinc-air battery catalyst according to claim 1, characterized in that, In step (4), the specific operation method is to heat the furnace from room temperature to 300-400℃ in an inert gas atmosphere for a period of time at a heating rate of 3-6℃ / min, and maintain this temperature for 1-3 h. Then, the furnace is heated to 700-900℃ and maintained at this temperature for 1-3 h. After cooling, the black powder obtained is washed with HCl aqueous solution, water, and ethanol. The black powder is then collected by centrifugation and dried in an oven at 60℃ to obtain CoFe@NC@NCNTs.

6. The method for preparing a zinc-air battery catalyst according to claim 5, characterized in that, The inert gas is one or both of Ar or N2.

7. A zinc-air battery catalyst, characterized in that, It is prepared by the preparation method according to any one of claims 1-6.

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