Preparation method of Cu particle-loaded spongy nitrogen-doped carbon material and air cathode of zinc-air battery

Abstract

The invention provides a preparation method of a Cu particle-loaded spongy nitrogen-doped carbon material and an air cathode of a zinc-air battery. The preparation method comprises the following steps: dispersing Cu-ZIF into a mixed solvent of N, N-dimethylformamide and absolute ethyl alcohol, and naming as A; dissolving zinc nitrate hexahydrate, pyrazine and polyvinylpyrrolidone into a mixed solvent of DMF (Dimethyl Formamide) and absolute ethyl alcohol, and naming as B; the preparation method comprises the following steps: dissolving meso-tetra (4-carboxyphenyl) porphin into a mixed solvent of DMF and absolute ethyl alcohol, and naming as C; and pouring the dispersion liquid A into the dispersion liquid B, uniformly stirring, dropwise adding the solution C into the dispersion liquid B, stirring at room temperature, heating in a water bath, centrifuging, washing and drying to obtain the Cu-ZIF-coated TCPP. And carrying out high-temperature pyrolysis on the Cu-ZIF-coated TCPP in a tubular furnace to obtain the Cu-coated NC composite material. The material has a rich pore structure, efficient oxygen reduction activity and excellent stability, has a certain application prospect in the field of oxygen reduction, and realizes high power density and excellent charge-discharge cycle stability as an air cathode of a zinc-air battery.

Description

Technical Field

[0001] The invention relates to the preparation of a Cu particle-loaded sponge-shaped nitrogen-doped carbon material and the application of a zinc-air battery, belonging to the field of zinc-air battery application. Background Art

[0002] As an electrochemical energy conversion and storage technology, zinc-air batteries have attracted widespread attention due to their low cost, environmental friendliness, and high safety performance. In zinc-air batteries, ORR and OER are the two fundamental catalytic reactions occurring at the air cathode during battery cycling, but they proceed very slowly in natural environments, are extremely inefficient, and result in high overpotentials for the battery. At high overpotentials, the transfer and consumption of O2 is enormous, resulting in insufficient mass transfer and reduced catalytic performance. Although rotating disk electrode (RDE) testing can significantly improve O2 diffusion and minimize the mass transfer resistance caused by forced convection at high rotation speeds (e.g., 1600 rpm), full-cell measurements are typically performed under static conditions, where reactant mass transfer is an extremely critical factor limiting energy output.

[0003] To address this issue, designing advanced catalyst structures to enhance oxygen reduction activity and increasing accessible site density by increasing metal loading and site utilization is a potential path to achieving high device performance. Porous materials are nanostructured materials with a generally simpler preparation process. Unlike hard template methods, which require the initial synthesis or purchase of a hard template, this significantly reduces the number of preparation steps, cost, and complexity. Furthermore, porous materials not only have a high specific surface area, which helps increase the number of active sites, but their porous structure also enhances gas diffusion and ion transport efficiency. Based on this background, to increase the material's porosity and thereby improve the exposure, mass transfer, and utilization efficiency of active sites, this patent uses Cu-ZIF as a precursor, followed by water-bath synthesis and high-temperature pyrolysis to produce a sponge-like Cu@NC composite. This composite exhibits high porosity, which not only exposes more active sites but also provides faster mass transport pathways, helping to improve the reaction kinetics of the electrocatalyst. Using it as the air cathode in zinc-air batteries, it achieves high power density and excellent charge-discharge cycling stability, showing promising application prospects in the zinc-air battery field. Summary of the Invention

[0004] The present invention aims to provide a Cu particle-loaded sponge-like nitrogen-doped carbon material as an air cathode for a zinc-air battery. The specific steps of the preparation method are as follows: Step 1: Add a methanol solution of zinc nitrate hexahydrate and copper chloride to a methanol solution of dimethylimidazole, stir at room temperature, centrifuge and wash, and dry to obtain a Cu-ZIF precursor.

[0005] Step 2: Disperse Cu-ZIF in a mixture of DMF and anhydrous ethanol (designated A). Dissolve zinc nitrate hexahydrate, pyrazine, and PVP in a mixture of DMF and anhydrous ethanol (designated B). Dissolve TCPP in a mixture of DMF and anhydrous ethanol (designated C). Pour dispersion A into dispersion B and stir until uniform. Then, add solution C dropwise to dispersion B. Stir at room temperature, heat in a water bath, centrifuge, wash, and dry to obtain Cu-ZIF@TCPP.

[0006] Step 3: The Cu-ZIF@TCPP was pyrolyzed at high temperature in a tube furnace to obtain the Cu@NC composite material.

[0007] The copper salt is selected from any one of copper chloride, copper nitrate, copper sulfate, copper acetate, and copper phosphate, and the molar amount of the added copper salt is 0.5-1.0 mmol.

[0008] The molar amount of the copper salt is 0.88 mmol.

[0009] The main reason for adding a copper salt (such as copper chloride) in step 1 is to introduce copper ions into the ZIF (zeolitic imidazole framework) structure, forming a Cu-ZIF precursor. The introduction of copper ions provides active sites for subsequent reactions. If copper salts are added in subsequent steps, uniform distribution of copper ions within the ZIF structure may not be achieved, thus affecting the properties of the final material.

[0010] In step 2, the volume ratio of DMF to anhydrous ethanol is 3-5:1. This solvent volume ratio is chosen primarily to optimize the solvent's polarity and solvency to ensure that the various reactants (such as zinc nitrate hexahydrate, pyrazine, PVP, and TCPP) are fully dissolved and evenly dispersed. DMF is a highly polar solvent that can dissolve a wide range of organic and inorganic compounds, while ethanol reduces the solution's viscosity and increases its fluidity, thereby promoting mixing and reaction between the reactants.

[0011] In step 2, the mass ratio of zinc nitrate hexahydrate, pyrazine and PVP is 1:0.09-0.36:2.00-7.00, and the mass ratio of Cu-ZIF to TCPP is 40-80. Zinc nitrate hexahydrate is one of the key raw materials for synthesizing framework materials, providing zinc ions, which are used here to construct the metal framework of sheet MOF. TCPP is a porphyrin derivative with four carboxyl substitutions that can form a stable complex with zinc ions. Here, TCPP acts as a ligand to bind to zinc ions to construct the metal framework of sheet MOF. Pyrazine also acts as a ligand in the reaction to help form the crystal structure of sheet MOF. At the same time, during the high-temperature pyrolysis process, pyrazine provides a nitrogen source to promote nitrogen doping in the material. PVP is usually used as a stabilizer or dispersant to help prevent the aggregation of metal species and ensure their uniformity.

[0012] In step 2, the water bath heating temperature is room temperature to 80°C; the water bath heating time is 3-12 h.

[0013] In step 2, the high-temperature pyrolysis temperature is 900-1000° C., and the pyrolysis time is 1-3 hours.

[0014] There are characteristic diffraction peaks at approximately 26°, 43°, 43°, 50° and 74°, and the difference between the characteristic diffraction peaks is no more than 1°; the Cu@NC composite material has a sponge-like porous structure with a size of 100-200 nm.

[0015] On the other hand, the present invention provides an air cathode for a zinc-air battery, wherein the air cathode for the zinc-air battery is the Cu particle-loaded sponge-like nitrogen-doped carbon material.

[0016] A zinc-air battery comprises the Cu particles loaded with the sponge-like nitrogen-doped carbon material. The sponge-like Cu@NC composite material and its preparation method of the present invention have the following significant features: (1) Excellent ORR activity, with an oxygen reduction half-wave potential of 0.84-0.867 V vs. RHE; (2) Rich pore structure, as the air cathode of zinc-air battery, it achieves high power density (the power density of quasi-solid-state battery can reach 600 mW cm -2 Above), excellent charge and discharge cycle stability (quasi-solid-state battery at 2 mA cm -2 It can be stably cycled for more than 35 h at a constant current density). BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 TEM spectrum of the sample prepared in Example 1.

[0018] Figure 2 XRD patterns of the samples prepared in Examples 1, 6, 7, and 9.

[0019] Figure 3 LSV curves of the samples prepared in Examples 1-11 and Pt / C.

[0020] Figure 4 The power density curve of the quasi-solid-state battery assembled from the samples prepared in Example 1 was measured.

[0021] Figure 5 The sample prepared in Example 1 was used as the air cathode of the quasi-solid-state battery at a current density of 2 mA cm -2 Constant current cycle charge and discharge curve.

[0022] Figure 6 The sample prepared in Example 1 was used as the air cathode of the liquid battery at a current density of 10 mA cm-2 Constant current cycle charge and discharge curve.

[0023] Figure 7 LSV curve of the sample prepared in Example 12.

[0024] Figure 8 The power density curve measured for the quasi-solid-state battery assembled from the samples prepared in Example 12.

[0025] Figure 9 The sample prepared in Example 12 was used as the air cathode of the quasi-solid-state battery at a current density of 2 mA cm -2 Constant current cycle charge and discharge curve.

[0026] Figure 10 This is the LSV curve of the sample prepared without adding pyrazine. DETAILED DESCRIPTION

[0027] Example 1 In the first step, 40 mL of methanol was added to beaker A, along with 6.5 g of dimethylimidazole, and stirred until dissolved. In beaker B, 80 mL of methanol was added to 2.8 g of zinc nitrate hexahydrate, and stirred until dissolved. 0.15 g of copper chloride was then added to beaker B and stirred until dissolved. The solution in beaker B was poured into beaker A, stirred evenly, and stirred at room temperature for 12 hours. The mixture was then centrifuged, washed three times with methanol, and dried to obtain the Cu-ZIF precursor.

[0028] In the second step, 450 mg of Cu-ZIF was dispersed in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named A; 9 mg of zinc nitrate hexahydrate, 1.6 mg of pyrazine, and 40 mg of PVP were dissolved in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named B; 8 mg of TCPP was dissolved in a mixed solvent of 3 mL of DMF and 1 mL of anhydrous ethanol and named C.

[0029] Pour dispersion A into dispersion B and stir evenly. Then, add solution C dropwise into dispersion B and stir at room temperature for 10 min. Then, stir in a water bath at 80 °C for 9 h. Centrifuge, wash with anhydrous ethanol, and dry to obtain Cu-ZIF@TCPP.

[0030] In the third step, the Cu-ZIF@TCPP was pyrolyzed at 900 °C in a tube furnace for 2 h to obtain a Cu@NC composite material, which was labeled as the sample of Example 1.

[0031] Figure 1This is the TEM image of the sample from Example 1. It shows a sponge-like, porous structure that retains the morphology of the precursor rhombic dodecahedron, with a size of approximately 200 nm. The porous structure within the sample facilitates maximum exposure of active sites, rapid mass transfer, and enhanced ORR activity. Figure 2 The XRD pattern of Example 1, a sample prepared under this embodiment, is shown in the figure. As shown in the figure, the diffraction peaks at approximately 26° and 43° correspond to the (002) and (101) crystal planes of graphitized carbon. In addition, the diffraction peaks at 43.3°, 50.4°, and 74.1° correspond to the (111), (200), and (220) crystal planes of Cu metal particles, respectively (PDF#85-1326), indicating that the phases of Example 1 are Cu metal particles and graphitized carbon.

[0032] The sample of this example was prepared into a slurry, dropped onto a rotating disk electrode, and its ORR performance was tested in an O2-saturated 0.1 M KOH solution. Figure 3 The ORR LSV curve shows that in Example 1, at 1600 rpm, the half-wave potential is 0.867 V vs. RHE and the limiting current density is 5.94 mA cm -2 , and the onset potential is 0.94 V vs. RHE. Obviously, the ORR performance of Example 1 is better than that of Pt / C, showing excellent ORR performance.

[0033] The catalyst was evenly drop-coated on hydrophobic HCP120 carbon paper as the air cathode, a polished zinc plate as the anode, and a PANa hydrogel film as the electrolyte to assemble a quasi-solid-state zinc-air battery. Figure 4 The discharge and power density curves of the quasi-solid-state battery assembled in Example 1 show that the battery power density is calculated to be 609 mW cm -2 The battery was tested at 2 mA cm -2 The cyclic charge and discharge can be stably cycled for more than 35 h under constant current density. Figure 5 ).

[0034] The catalyst was evenly drop-coated on hydrophobic HCP120 carbon paper as the air cathode, a polished zinc plate was used as the anode, and a KOH solution containing 0.2 M Zn(OAc)2·2H2O was used as the electrolyte to assemble a liquid zinc-air battery. The liquid battery assembled with this example sample was tested at 10 mA cm -2 Cyclic charge and discharge at a constant current density can be stably cycled for more than 800 h ( Figure 6 ), from which it can be concluded that Example 1 has excellent battery performance as an air cathode.

[0035] Example 2 In the first step, 40 mL of methanol was added to beaker A, along with 6.5 g of dimethylimidazole, and stirred until dissolved. In beaker B, 80 mL of methanol was added to 2.8 g of zinc nitrate hexahydrate, and stirred until dissolved. 0.15 g of copper chloride was then added to beaker B and stirred until dissolved. The solution in beaker B was poured into beaker A, stirred evenly, and stirred at room temperature for 12 hours. The mixture was then centrifuged, washed three times with methanol, and dried to obtain the Cu-ZIF precursor.

[0036] In the second step, 450 mg of Cu-ZIF was dispersed in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named A; 9 mg of zinc nitrate hexahydrate, 0.8 mg of pyrazine, and 40 mg of PVP were dissolved in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named B; 8 mg of TCPP was dissolved in a mixed solvent of 3 mL of DMF and 1 mL of anhydrous ethanol and named C.

[0037] Dispersion A was poured into solution B and stirred until uniform. Solution C was then added dropwise to solution B, stirred at room temperature for 10 minutes, then stirred in an 80°C water bath for 9 hours. The mixture was centrifuged, washed with anhydrous ethanol, and dried to obtain Cu-ZIF@TCPP. In the third step, the Cu-ZIF@TCPP was pyrolyzed at 900°C in a tube furnace for 2 hours to obtain a Cu@NC composite material, designated as Example 2.

[0038] The sample of this example was prepared into a slurry, dropped onto a rotating disk electrode, and its ORR performance was tested in an O2-saturated 0.1 M KOH solution. Figure 3 The ORR LSV curve shows that in Example 2, at 1600 rpm, the half-wave potential is 0.868 V vs. RHE and the limiting current density is 5.64 mA cm -2 , and the onset potential is 0.96 V vs. RHE. Obviously, the ORR performance of Example 2 is better than that of Pt / C, showing excellent ORR performance.

[0039] Example 3 In the first step, 40 mL of methanol was added to beaker A, along with 6.5 g of dimethylimidazole, and stirred until dissolved. In beaker B, 80 mL of methanol was added to 2.8 g of zinc nitrate hexahydrate, and stirred until dissolved. 0.15 g of copper chloride was then added to beaker B and stirred until dissolved. The solution in beaker B was poured into beaker A, stirred evenly, and stirred at room temperature for 12 hours. The mixture was then centrifuged, washed three times with methanol, and dried to obtain the Cu-ZIF precursor.

[0040] In the second step, 450 mg of Cu-ZIF was dispersed in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named A; 9 mg of zinc nitrate hexahydrate, 3.2 mg of pyrazine, and 40 mg of PVP were dissolved in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named B; 8 mg of TCPP was dissolved in a mixed solvent of 3 mL of DMF and 1 mL of anhydrous ethanol and named C.

[0041] Dispersion A was poured into solution B and stirred until uniform. Solution C was then added dropwise to solution B, stirred at room temperature for 10 minutes, then stirred in an 80°C water bath for 9 hours. The mixture was centrifuged, washed with anhydrous ethanol, and dried to obtain Cu-ZIF@TCPP. In the third step, the Cu-ZIF@TCPP was pyrolyzed at 900°C in a tube furnace for 2 hours to obtain a Cu@NC composite material, designated as Example 3.

[0042] The sample of this example was prepared into a slurry, dropped onto a rotating disk electrode, and its ORR performance was tested in an O2-saturated 0.1 M KOH solution. Figure 3 The ORR LSV curve shows that in Example 3, at 1600 rpm, the half-wave potential is 0.863 V vs. RHE and the limiting current density is 5.61 mA cm -2 , and the onset potential is 0.94 V vs. RHE. Obviously, the ORR performance of Example 3 is better than that of Pt / C, showing excellent ORR performance.

[0043] Example 4 In the first step, 40 mL of methanol was added to beaker A, along with 6.5 g of dimethylimidazole, and stirred until dissolved. In beaker B, 80 mL of methanol was added to 2.8 g of zinc nitrate hexahydrate, and stirred until dissolved. 0.15 g of copper chloride was then added to beaker B and stirred until dissolved. The solution in beaker B was poured into beaker A, stirred evenly, and stirred at room temperature for 12 hours. The mixture was then centrifuged, washed three times with methanol, and dried to obtain the Cu-ZIF precursor.

[0044] In the second step, 450 mg of Cu-ZIF was dispersed in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named A; 9 mg of zinc nitrate hexahydrate, 3.2 mg of pyrazine, and 20 mg of PVP were dissolved in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named B; 8 mg of TCPP was dissolved in a mixed solvent of 3 mL of DMF and 1 mL of anhydrous ethanol and named C.

[0045] Dispersion A was poured into solution B and stirred until uniform. Solution C was then added dropwise to solution B, stirred at room temperature for 10 minutes, then stirred in an 80°C water bath for 9 hours. The mixture was centrifuged, washed with anhydrous ethanol, and dried to obtain Cu-ZIF@TCPP. In the third step, the Cu-ZIF@TCPP was pyrolyzed at 900°C in a tube furnace for 2 hours to obtain a Cu@NC composite material, designated as Example 4.

[0046] The sample of this example was prepared into a slurry, dropped onto a rotating disk electrode, and its ORR performance was tested in an O2-saturated 0.1 M KOH solution. Figure 3 The ORR LSV curve shows that in Example 4, at 1600 rpm, the half-wave potential is 0.853 V vs. RHE and the limiting current density is 5.29 mA cm -2 , and the onset potential is 0.94 V vs. RHE. Obviously, the ORR performance of Example 4 is better than that of Pt / C, showing excellent ORR performance.

[0047] Example 5 In the first step, 40 mL of methanol was added to beaker A, along with 6.5 g of dimethylimidazole, and stirred until dissolved. In beaker B, 80 mL of methanol was added to 2.8 g of zinc nitrate hexahydrate, and stirred until dissolved. 0.15 g of copper chloride was then added to beaker B and stirred until dissolved. The solution in beaker B was poured into beaker A, stirred evenly, and stirred at room temperature for 12 hours. The mixture was then centrifuged, washed three times with methanol, and dried to obtain the Cu-ZIF precursor.

[0048] In the second step, 450 mg of Cu-ZIF was dispersed in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named A; 9 mg of zinc nitrate hexahydrate, 3.2 mg of pyrazine, and 60 mg of PVP were dissolved in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named B; 8 mg of TCPP was dissolved in a mixed solvent of 3 mL of DMF and 1 mL of anhydrous ethanol and named C.

[0049] Dispersion A was poured into solution B and stirred until uniform. Solution C was then added dropwise to solution B, stirred at room temperature for 10 minutes, then stirred in an 80°C water bath for 9 hours. The mixture was centrifuged, washed with anhydrous ethanol, and dried to obtain Cu-ZIF@TCPP. In the third step, the Cu-ZIF@TCPP was pyrolyzed at 900°C in a tube furnace for 2 hours to obtain a Cu@NC composite material, designated as Example 5.

[0050] The sample of this example was prepared into a slurry, dropped onto a rotating disk electrode, and its ORR performance was tested in an O2-saturated 0.1 M KOH solution. Figure 3 The ORR LSV curve shows that the half-wave potential of Example 5 at 1600 rpm is 0.856 V vs. RHE, and the limiting current density is 5.83 mA cm -2 , and the onset potential is 0.94 V vs. RHE. Obviously, the ORR performance of Example 5 is better than that of Pt / C, showing excellent ORR performance.

[0051] Example 6 In the first step, the preparation of Cu-ZIF precursor is the same as in Example 1.

[0052] In the second step, 450 mg of Cu-ZIF was dispersed in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named A; 9 mg of zinc nitrate hexahydrate, 1.6 mg of pyrazine, and 40 mg of PVP were dissolved in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named B; 8 mg of TCPP was dissolved in a mixed solvent of 3 mL of DMF and 1 mL of anhydrous ethanol and named C.

[0053] Pour dispersion A into dispersion B and stir evenly. Then, add solution C dropwise into dispersion B and stir at room temperature for 10 min. Then, stir in a water bath at 80 °C for 3 h. Centrifuge, wash with anhydrous ethanol, and dry to obtain Cu-ZIF@TCPP.

[0054] In the third step, the Cu-ZIF@TCPP was pyrolyzed at 900 °C in a tube furnace for 2 h to obtain a Cu@NC composite material, which was labeled as Example 6 sample.

[0055] Figure 2 The XRD pattern of Sample Example 6 prepared under this embodiment is shown in the figure. As shown in the figure, the diffraction peaks at approximately 26° and 43° correspond to the (002) and (101) crystal planes of graphitized carbon. In addition, the diffraction peaks at 43.3°, 50.4°, and 74.1° correspond to the (111), (200), and (220) crystal planes of Cu metal particles, respectively (PDF#85-1326), indicating that the phases of Sample 6 are Cu metal particles and graphitized carbon.

[0056] The sample of this example was prepared into a slurry, dropped onto a rotating disk electrode, and its ORR performance was tested in an O2-saturated 0.1 M KOH solution. Figure 3 The ORR LSV curve shows that in Example 6, at 1600 rpm, the half-wave potential is 0.84 V vs. RHE and the limiting current density is 5.64 mA cm -2, with an onset potential of 0.92 V vs. RHE. The ORR performance of Example 6 is close to that of Pt / C, showing excellent ORR performance.

[0057] Example 7 In the first step, the preparation of Cu-ZIF precursor is the same as in Example 1.

[0058] In the second step, 450 mg of Cu-ZIF was dispersed in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named A; 9 mg of zinc nitrate hexahydrate, 1.6 mg of pyrazine, and 40 mg of PVP were dissolved in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named B; 8 mg of TCPP was dissolved in a mixed solvent of 3 mL of DMF and 1 mL of anhydrous ethanol and named C.

[0059] Pour dispersion A into dispersion B and stir evenly. Then, add solution C dropwise into dispersion B and stir at room temperature for 10 min. Then, stir in a water bath at 80 °C for 12 h. Centrifuge, wash with anhydrous ethanol, and dry to obtain Cu-ZIF@TCPP.

[0060] In the third step, the Cu-ZIF@TCPP was pyrolyzed at 900 °C in a tube furnace for 2 h to obtain a Cu@NC composite material, which was labeled as sample 7 of Example 7.

[0061] Figure 2 The XRD pattern of Sample Example 7 prepared under this embodiment is shown in the figure. As shown in the figure, the diffraction peaks at approximately 26° and 43° correspond to the (002) and (101) crystal planes of graphitized carbon. In addition, the diffraction peaks at 43.3°, 50.4°, and 74.1° correspond to the (111), (200), and (220) crystal planes of Cu metal particles, respectively (PDF#85-1326), indicating that the phases of Example 7 are Cu metal particles and graphitized carbon.

[0062] The sample of this example was prepared into a slurry, dropped onto a rotating disk electrode, and its ORR performance was tested in an O2-saturated 0.1 M KOH solution. Figure 3 The ORR LSV curve shows that in Example 7, at 1600 rpm, the half-wave potential is 0.85 V vs. RHE and the limiting current density is 5.68 mA cm -2 , with an onset potential of 0.93 V vs. RHE. The ORR performance of Example 7 is close to that of Pt / C, showing excellent ORR performance.

[0063] Example 8 In the first step, the preparation of Cu-ZIF precursor is the same as in Example 1.

[0064] In the second step, 450 mg of Cu-ZIF was dispersed in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named A; 9 mg of zinc nitrate hexahydrate, 1.6 mg of pyrazine, and 40 mg of PVP were dissolved in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named B; 8 mg of TCPP was dissolved in a mixed solvent of 3 mL of DMF and 1 mL of anhydrous ethanol and named C.

[0065] Dispersion A was poured into dispersion B and stirred evenly. Then, solution C was added dropwise into dispersion B and stirred at room temperature for 10 min. The mixture was then stirred continuously at room temperature for 9 h. The mixture was centrifuged and washed with anhydrous ethanol and dried to obtain Cu-ZIF@TCPP.

[0066] In the third step, the Cu-ZIF@TCPP was pyrolyzed at 900 °C in a tube furnace for 2 h to obtain a Cu@NC composite material, which was labeled as Example 8 sample.

[0067] The sample of this example was prepared into a slurry, dropped onto a rotating disk electrode, and its ORR performance was tested in an O2-saturated 0.1 M KOH solution. Figure 3 The ORR LSV curve shows that in Example 8, at 1600 rpm, the half-wave potential is 0.846 V vs. RHE and the limiting current density is 6.04 mA cm -2 , with an onset potential of 0.92 V vs. RHE. The ORR performance of Example 8 is close to that of Pt / C, showing excellent ORR performance.

[0068] Example 9 In the first step, the preparation of Cu-ZIF precursor is the same as in Example 1.

[0069] In the second step, 450 mg of Cu-ZIF was dispersed in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named A; 9 mg of zinc nitrate hexahydrate, 1.6 mg of pyrazine, and 40 mg of PVP were dissolved in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named B; 8 mg of TCPP was dissolved in a mixed solvent of 3 mL of DMF and 1 mL of anhydrous ethanol and named C.

[0070] Dispersion A was poured into solution B and stirred until uniform. Solution C was then added dropwise to solution B, stirred at room temperature for 10 minutes, then stirred in a 60°C water bath for 9 hours. The mixture was centrifuged, washed with anhydrous ethanol, and dried to obtain Cu-ZIF@TCPP. In the third step, the Cu-ZIF@TCPP was pyrolyzed at 900°C in a tube furnace for 2 hours to obtain a Cu@NC composite material, designated as Example 9.

[0071] Figure 2 The XRD pattern of Sample Example 9 prepared under this embodiment is shown in the figure. As shown in the figure, the diffraction peaks at approximately 26° and 43° correspond to the (002) and (101) crystal planes of graphitized carbon. In addition, the diffraction peaks at 43.3°, 50.4°, and 74.1° correspond to the (111), (200), and (220) crystal planes of Cu metal particles, respectively (PDF#85-1326), indicating that the physical phases of Example 9 are Cu metal particles and graphitized carbon.

[0072] The sample of this example was prepared into a slurry, dropped onto a rotating disk electrode, and its ORR performance was tested in an O2-saturated 0.1 M KOH solution. Figure 3 The ORR LSV curve shows that in Example 9, at 1600 rpm, the half-wave potential is 0.844 V vs. RHE and the limiting current density is 5.76 mA cm -2 , with an onset potential of 0.92 V vs. RHE. The ORR performance of Example 9 is close to that of Pt / C, showing excellent ORR performance.

[0073] Example 10 In the first step, 40 mL of methanol was added to beaker A, along with 6.5 g of dimethylimidazole, and stirred until dissolved. In beaker B, 80 mL of methanol was added to 2.8 g of zinc nitrate hexahydrate, and stirred until dissolved. 0.17 g of copper nitrate was then added to beaker B and stirred until dissolved. The solution in beaker B was poured into beaker A, stirred evenly, and stirred at room temperature for 12 hours. The mixture was then centrifuged, washed three times with methanol, and dried to obtain the Cu-ZIF precursor.

[0074] In the second step, 450 mg of Cu-ZIF was dispersed in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named A; 9 mg of zinc nitrate hexahydrate, 1.6 mg of pyrazine, and 40 mg of PVP were dissolved in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named B; 8 mg of TCPP was dissolved in a mixed solvent of 3 mL of DMF and 1 mL of anhydrous ethanol and named C.

[0075] Pour dispersion A into dispersion B and stir evenly. Then, add solution C dropwise into dispersion B and stir at room temperature for 10 min. Then, stir in a water bath at 80 °C for 9 h. Centrifuge, wash with anhydrous ethanol, and dry to obtain Cu-ZIF@TCPP.

[0076] In the third step, Cu-ZIF@TCPP was pyrolyzed at 900 °C in a tube furnace for 2 h to obtain a Cu@NC composite material, which was labeled as Example 10 sample.

[0077] The sample of this example was prepared into a slurry, dropped onto a rotating disk electrode, and its ORR performance was tested in an O2-saturated 0.1 M KOH solution. Figure 3 The ORR LSV curve shows that at 1600 rpm, the half-wave potential of Example 10 is 0.85 V vs. RHE, and the limiting current density is 5.91 mA cm -2 , with an onset potential of 0.93 V vs. RHE. The ORR performance of Example 10 is close to that of Pt / C, showing excellent ORR performance.

[0078] Example 11 In the first step, 40 mL of methanol was added to beaker A, along with 6.5 g of dimethylimidazole, and stirred until dissolved. In beaker B, 80 mL of methanol was added to 2.8 g of zinc nitrate hexahydrate, and stirred until dissolved. 0.23 g of copper acetylacetonate was then added to beaker B and stirred until dissolved. The solution in beaker B was poured into beaker A, stirred evenly, and stirred at room temperature for 12 hours. The mixture was then centrifuged, washed three times with methanol, and dried to obtain the Cu-ZIF precursor.

[0079] In the second step, 450 mg of Cu-ZIF was dispersed in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named A; 9 mg of zinc nitrate hexahydrate, 1.6 mg of pyrazine, and 40 mg of PVP were dissolved in a mixed solvent of 9 mL of DMF and 3 mL of anhydrous ethanol, named B; 8 mg of TCPP was dissolved in a mixed solvent of 3 mL of DMF and 1 mL of anhydrous ethanol and named C.

[0080] Pour dispersion A into dispersion B and stir evenly. Then, add solution C dropwise into dispersion B and stir at room temperature for 10 min. Then, stir in a water bath at 80 °C for 9 h. Centrifuge, wash with anhydrous ethanol, and dry to obtain Cu-ZIF@TCPP.

[0081] In the third step, Cu-ZIF@TCPP was pyrolyzed at 900 °C in a tube furnace for 2 h to obtain a Cu@NC composite material, which was labeled as Example 11 sample.

[0082] The sample of this example was prepared into a slurry, dropped onto a rotating disk electrode, and its ORR performance was tested in an O2-saturated 0.1 M KOH solution. Figure 3 The ORR LSV curve shows that for Example 11 at 1600 rpm, the half-wave potential is 0.847 V vs. RHE and the limiting current density is 5.86 mA cm -2 , with an onset potential of 0.95 V vs. RHE. The ORR performance of Example 11 is close to that of Pt / C, showing excellent ORR performance.

[0083] Compared with Example 1, the experimental steps and the dosage of other drugs are kept unchanged, and Cu-ZIF is directly carbonized without subsequent treatment. The ORR LSV curve of the obtained sample is as follows: Figure 7 As shown in Example 12, it can be seen from the figure that at 1600 rpm, its half-wave potential dropped to 0.826 V vs. RHE and the limiting current density dropped to 5.7 mA cm -2 , its ORR performance is significantly attenuated. The catalyst is evenly drop-coated on hydrophobic HCP120 carbon paper as the air cathode, a polished zinc plate as the anode, and a PANa hydrogel film as the electrolyte to assemble a quasi-solid-state zinc-air battery. Figure 8 The discharge and power density curves of the quasi-solid-state battery assembled in Example 12 show that the battery power density is calculated to be 354 mW cm -2 . Figure 9 This cell is placed at 2 mA cm -2 The cyclic charge and discharge under constant current density can only be stably cycled for 20 h, from which it can be concluded that the battery performance is poor.

[0084] Compared with Example 1, pyrazine was not added in the second step, and the other experimental steps and drug dosages remained unchanged. The half-wave potential of the obtained sample decreased to 0.80 V vs. RHE at 1600 rpm due to the reduced nitrogen content, and its ORR performance was significantly attenuated. Figure 10 As shown in Example 13.

Claims

1. A method for preparing a Cu particle-loaded sponge-like nitrogen-doped carbon material, characterized in that: The steps include: Step 1: Add a methanol solution of zinc nitrate hexahydrate and copper salt to a methanol solution of dimethylimidazole, stir at room temperature, centrifuge and wash, and dry to obtain a Cu-ZIF precursor; Step 2: Disperse the Cu-ZIF precursor into a mixed solvent of DMF and anhydrous ethanol, named A; Zinc nitrate hexahydrate, pyrazine and polyvinylpyrrolidone (PVP) were dissolved in a mixed solvent of DMF and anhydrous ethanol, named B; Meso-tetrakis(4-carboxyphenyl)porphine TCPP was dissolved in a mixed solvent of DMF and anhydrous ethanol and named C; Pour dispersion A into dispersion B and stir evenly, then add solution C dropwise into dispersion B, stir at room temperature, heat in a water bath, centrifuge, wash, and dry to obtain Cu-ZIF@TCPP. Step 3: The Cu-ZIF@TCPP was pyrolyzed at high temperature in a tube furnace to obtain Cu particle-loaded sponge-like nitrogen-doped carbon material Cu@NC.

2. The method for preparing the Cu particle-loaded sponge-like nitrogen-doped carbon material according to claim 1, characterized in that: In step 1, the copper salt is selected from any one of copper chloride, copper nitrate, copper sulfate, copper acetate, and copper phosphate, and the molar amount of the added copper salt is 0.5-1.0 mmol.

3. The method for preparing the Cu particle-loaded sponge-like nitrogen-doped carbon material according to claim 1, characterized in that: In step 2, the volume ratio of DMF to anhydrous ethanol is 3-5:

1.

4. The method for preparing the Cu particle-loaded sponge-like nitrogen-doped carbon material according to claim 1, characterized in that: In step 2, the mass ratio of zinc nitrate hexahydrate, pyrazine and PVP is 1:0.09-0.36:2.00-7.

00.

5. The method for preparing the Cu particle-loaded sponge-like nitrogen-doped carbon material according to claim 1, characterized in that: In step 2, the mass ratio of Cu-ZIF to TCPP is 40-80.

6. The method for preparing a Cu particle-loaded sponge-like nitrogen-doped carbon material according to claim 1, characterized in that: In step 2, the water bath heating temperature is room temperature to 80°C; the water bath heating time is 3-12 h.

7. The method for preparing a Cu particle-loaded sponge-like nitrogen-doped carbon material according to claim 1, characterized in that: In step 3, the high-temperature pyrolysis temperature is 900-1000° C., and the pyrolysis time is 1-3 hours.

8. The Cu particle-supported sponge-like nitrogen-doped carbon material prepared by the method according to any one of claims 1 to 7, characterized in that: The prepared Cu particle-loaded sponge-like nitrogen-doped carbon material has characteristic diffraction peaks at 26°, 43°, 43°, 50° and 74°; the Cu@NC composite material has a sponge-like porous structure with a size of 100-200 nm.

9. Zinc-air battery air cathode, characterized in that The air cathode of the zinc-air battery is the Cu particle-loaded sponge-like nitrogen-doped carbon material as described in claim 8.

10. A zinc-air battery, characterized in that: It comprises the Cu particle-loaded sponge-like nitrogen-doped carbon material according to claim 8.

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