Zinc-air battery catalyst and preparation method thereof

Abstract

The invention relates to the technical field of zinc-air battery catalysts, specifically a zinc-air battery catalyst and a preparation method thereof. The preparation method comprises the following steps: S1, dispersing MXene powder in deionized water and ultrasonically treating it for 1 hour to obtain a mixed solution; S2, adding nickel nitrate hexahydrate, cobalt nitrate hexahydrate, urea, and polyvinylpyrrolidone to the mixed solution from step S1 for a hydrothermal reaction; S3, vacuum drying to obtain a first solid material; S4, adding the first solid material to a glucose and nano-silica solution, adjusting the pH, and evaporating to obtain a second solid material; S5, calcining and then treating it with a potassium hydroxide solution to obtain a third solid material containing a carbon layer; S6, calcining the third solid material with melamine to obtain a catalyst. The zinc-air battery catalyst prepared by the present invention has excellent ORR and OER catalytic performance and strong recycling capacity.

Description

Technical Field

[0001] The present invention relates to the technical field of zinc-air battery catalysts, in particular to a zinc-air battery catalyst and a preparation method thereof. Background Art

[0002] Growing environmental and energy issues and the rapid consumption of non-renewable fossil energy have made the development of efficient and sustainable energy conversion devices, such as metal-air batteries, fuel cells, and electrochemical water splitting, a key solution to this problem. Rechargeable zinc-air batteries (ZABs) have attracted much attention due to their high theoretical energy density, high cost-effectiveness, safety, and abundant zinc reserves. However, the slow cathode kinetics of ZABs result in high thermodynamic overpotential and low output power, which limits their practical application. Currently, the most commonly used noble metal and oxide electrocatalysts are Pt / C and RuO2, but their high price, limited tolerance, and instability have seriously hindered their practical commercialization. Therefore, there is an urgent need to rationally design the physicochemical structure of ZAB air cathode catalysts to prepare efficient, stable, and low-cost cathode bifunctional electrocatalysts.

[0003] MXene is a novel class of two-dimensional materials with a graphene-like structure, composed of transition metal carbides, nitrides, or carbonitrides. Due to their unique 2D structure, high conductivity, and hydrophilicity, MXene materials have attracted considerable attention and show great potential for application in electrocatalysis. By bridging NiCo nanoalloy-modified carbon nanotubes (CNTs) between MXene layers, novel 3D MXene-based electrocatalysts can be constructed, where the CNTs and MXene provide a robust sheath and fast charge transfer pathways. This strategy for constructing complex three-dimensional MXene nanocomposites offers new insights into the preparation of oxygen electrode catalysts for renewable clean energy devices.

[0004] However, due to the clustering phenomenon of double-layered hydroxides (LDHs) during the preparation process, their conductivity and stability are poor, which limits their practical application, as well as the phenomenon of aggregation between MXene layers. In this case, selecting MXene as a substrate can effectively avoid the agglomeration phenomenon, increase the specific surface area and improve the electrical conductivity. Then, by pyrolysis with melamine, nano-alloy-modified nitrogen-doped carbon nanotubes can be obtained to bridge the MXene layers, forming a large number of reaction active sites. In addition, the present invention in situ grows NiCo double hydroxide on the MXene layer, pyrolyzes it together with a carbon source to form a carbon layer, and then pyrolyzes it with melamine to improve the interfacial bonding ability, synthesizing a new three-dimensional catalyst in which NiCo nano-alloy-modified carbon nanotubes are bridged between MXene layers, which is used as an efficient bifunctional oxygen electrocatalyst for use as a cathode catalyst in zinc-air batteries. Summary of the Invention

[0005] The purpose of the present invention is to provide a zinc-air battery catalyst and a preparation method thereof to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

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

[0008] S1. Disperse MXene powder in deionized water and ultrasonicate for 1 h to obtain a mixed solution;

[0009] S2. Add nickel nitrate hexahydrate (Ni(NO3)2·6H2O), cobalt nitrate hexahydrate (Co(NO3)2·6H2O), urea, and polyvinylpyrrolidone to the mixed solution of step S1, and stir the mixture at 25°C for 1 hour. Continue to add anhydrous ethanol and stir and mix for 30 minutes to obtain a mixture. Transfer the mixture to a PTFE-lined autoclave and react at 90°C for 12 hours.

[0010] S3. After the reaction of step S2 is cooled, the product is vacuum filtered, washed with sufficient deionized water, and dried in a vacuum oven at 100° C. for 10 hours to obtain a first solid material;

[0011] S4, adding the first solid material obtained in step S3 to a deionized water solution containing glucose and nano-silica, continuing to dropwise add 28% by mass of ammonia water, adjusting the pH to 10, continuously ultrasonically dispersing for 2 h, and then removing the deionized water by rotary evaporation at 80° C. to obtain a second solid material;

[0012] S5, calcining the second solid material obtained in step S4 at a heating rate of 10°C / min in an Ar atmosphere, raising the temperature to 600-800°C, and keeping the temperature for 3 hours, dispersing the calcined product in a potassium hydroxide solution with a concentration of 2 mol / L, heating to 100°C and continuously stirring for 3-5 hours, filtering the product, washing it with sufficient deionized water, and vacuum drying it to obtain a third solid material;

[0013] S6. Mixing the third solid material obtained in step S5 with melamine, calcining the mixture in an Ar atmosphere at a heating rate of 5° C. / min, raising the temperature to 700-900° C., and keeping the temperature for 2 hours to obtain a zinc-air battery catalyst.

[0014] Furthermore, the MXene powder used in step S1 is Ti3C2T x , the mass ratio between MXene powder and deionized water is 1:1200.

[0015] Furthermore, the mass ratio of Ni(NO3)2·6H2O, Co(NO3)2·6H2O, urea and polyvinylpyrrolidone in step S2 to the MXene powder in step S1 is 1:1:(1.5-2.5):(0.3-0.8):0.025; the mass ratio of anhydrous ethanol in step S2 to deionized water in step S1 is 0.8:1.

[0016] Furthermore, in the deionized water solution of step S4, the mass fraction of glucose is 5-10%, the mass fraction of nano-silicon dioxide is 1-5%, and the particle size of nano-silicon dioxide is 1-10 nm.

[0017] Furthermore, the mass ratio of the deionized water solution containing glucose and nano-silicon dioxide to the sum of the masses of Ni(NO3)2·6H2O and Co(NO3)2·6H2O in step S4 is (5-10):1.

[0018] Furthermore, in step S6, the mass ratio of melamine to the sum of the masses of Ni(NO3)2·6H2O and Co(NO3)2·6H2O is (1.5-2.5):1.

[0019] A zinc-air battery catalyst is prepared by the above-mentioned zinc-air battery catalyst preparation method.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. This invention develops a novel three-dimensional ZABs catalyst prepared by combining a hydrothermal method with high-temperature solid-phase synthesis. The high specific surface area and porosity facilitate the full exposure of active sites. The carbon nanotubes and MXene formed after melamine pyrolysis provide a strong sheath and fast charge transfer channels, resulting in a high catalytic effect.

[0022] 2. The in-situ growth of double-layered hydroxide on the MXene layer during the preparation process of the present invention can effectively avoid the agglomeration of double-layered hydroxide and better intercalate. The nanoparticles formed by calcining the double-layered hydroxide have a larger specific surface area and provide more catalytic sites.

[0023] 3. In the present invention, glucose is combined with a composite material of MXene and double-layered hydroxide. Through calcination, a carbon layer can be formed on the surface of the formed metal nanoparticles, thereby improving the interfacial bonding strength between the carbon nanotubes and the metal nanoparticles and increasing the number of cycles. In addition, a small amount of nano-silicon dioxide is added, which is combined with the carbon layer. Through etching with potassium hydroxide solution, the surface area of ​​the metal nanoparticles is increased, exposing more active sites, which not only promotes the formation of carbon nanotubes but also improves the catalytic effect of the zinc-air battery catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The process flow chart of the present invention for preparing zinc-air battery catalyst;

[0025] Figure 2 This is a SEM image (500 nm) of the zinc-air battery catalyst prepared in Example 1 of the present invention;

[0026] Figure 3 This is a SEM image (1 μm) of the zinc-air battery catalyst prepared in Example 1 of the present invention;

[0027] Figure 4 This is an energy dispersive X-ray spectrum of the zinc-air battery catalyst prepared in Example 1 of the present invention;

[0028] Figure 5 These are the ORR performance test curves of the zinc-air battery catalysts prepared in Examples 1-3 of the present invention and Comparative Examples 1-3;

[0029] Figure 6 The OER performance test curves of zinc-air battery catalysts prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention are shown;

[0030] Figure 7 Table 2 shows the cycle test results of ZAB assembled from the zinc-air battery catalysts prepared in Example 1 and Comparative Example 2 of the present invention;

[0031] Figure 8 This is the XRD pattern of the present invention. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] See also Figures 1 to 8 , the present invention provides:

[0034] Example 1

[0035] A method for preparing a zinc-air battery catalyst comprises the following steps:

[0036] S1, 25 mg of MXene powder (Ti3C2T x powder) was dispersed in 30 g of deionized water and ultrasonically treated for 1 h at an ultrasonic frequency of 30 kHz to obtain a mixed solution;

[0037] S2. Add 1 g of Ni(NO3)2·6H2O, 1 g of Co(NO3)2·6H2O, 2 g of urea, and 0.5 g of polyvinylpyrrolidone to the mixed solution of step S1, and stir the mixture at 25°C for 1 hour. Then, add 24 g of anhydrous ethanol and stir for 30 minutes to obtain a mixture. Transfer the mixture to a PTFE-lined autoclave and react at 90°C for 12 hours.

[0038] S3. After the reaction of step S2 is cooled, the product is vacuum filtered, washed with sufficient deionized water, and dried in a vacuum oven at 100° C. for 10 hours to obtain a first solid material;

[0039] S4, adding the first solid material obtained in step S3 to a deionized water solution containing glucose and nano-silica, wherein the mass fraction of glucose is 7%, the mass fraction of nano-silica is 2%, the particle size of the nano-silica used is 5 nm, and the total weight of the deionized water solution containing glucose and nano-silica is 15 g, continuing to dropwise add ammonia water with a mass fraction of 28%, adjusting the pH to 10, and continuously ultrasonically disperse for 2 h at an ultrasonic frequency of 30 kHz, and then removing the deionized water by rotary evaporation at 80° C. to obtain a second solid material;

[0040] S5, calcining the second solid material obtained in step S4 at a heating rate of 10°C / min in an Ar atmosphere, raising the temperature to 700°C, and keeping the temperature for 3 hours, dispersing the calcined product in a potassium hydroxide solution with a concentration of 2 mol / L, heating to 100°C and continuously stirring for 4 hours, filtering the product, washing it with sufficient deionized water, and vacuum drying it to obtain a third solid material;

[0041] S6. Mix the third solid material obtained in step S5 with 2 g of melamine, and calcine the mixture in an Ar atmosphere at a heating rate of 5° C. / min, raise the temperature to 800° C., and keep the temperature for 2 h to obtain a zinc-air battery catalyst.

[0042] Example 2

[0043] A method for preparing a zinc-air battery catalyst comprises the following steps:

[0044] S1, 25 mg of MXene powder (Ti3C2T x powder) was dispersed in 30 g of deionized water and ultrasonically treated for 1 h at an ultrasonic frequency of 30 kHz to obtain a mixed solution;

[0045] S2. Add 1 g of Ni(NO3)2·6H2O, 1 g of Co(NO3)2·6H2O, 1.5 g of urea, and 0.3 g of polyvinylpyrrolidone to the mixed solution of step S1, and stir the mixture at 25°C for 1 hour. Then, add 24 g of anhydrous ethanol and stir for 30 minutes to obtain a mixture. Transfer the mixture to a PTFE-lined autoclave and react at 90°C for 12 hours.

[0046] S3. After the reaction of step S2 is cooled, the product is vacuum filtered, washed with sufficient deionized water, and dried in a vacuum oven at 100° C. for 10 hours to obtain a first solid material;

[0047] S4, adding the first solid material obtained in step S3 to a deionized water solution containing glucose and nano-silica, wherein the mass fraction of glucose is 5%, the mass fraction of nano-silica is 1%, the particle size of the nano-silica used is 1 nm, and the total weight of the deionized water solution containing glucose and nano-silica is 10 g, continuing to dropwise add ammonia water with a mass fraction of 28%, adjusting the pH to 10, and continuously ultrasonically dispersing for 2 h at an ultrasonic frequency of 30 kHz, and then removing the deionized water by rotary evaporation at 80° C. to obtain a second solid material;

[0048] S5, calcining the second solid material obtained in step S4 at a heating rate of 10°C / min in an Ar atmosphere, raising the temperature to 600°C, and keeping the temperature for 3 hours, dispersing the calcined product into a potassium hydroxide solution with a concentration of 2 mol / L, heating to 100°C and continuously stirring for 3 hours, filtering the product, washing it with sufficient deionized water, and vacuum drying it to obtain a third solid material;

[0049] S6. Mix the third solid material obtained in step S5 with 1.5 g of melamine, and calcine the mixture in an Ar atmosphere at a heating rate of 5° C. / min, raise the temperature to 700° C., and keep the temperature for 2 h to obtain a zinc-air battery catalyst.

[0050] Example 3

[0051] A method for preparing a zinc-air battery catalyst comprises the following steps:

[0052] S1, 25mg MXene powder (Ti3C2T x powder) was dispersed in 30 g of deionized water and ultrasonically treated for 1 h at an ultrasonic frequency of 30 kHz to obtain a mixed solution;

[0053] S2. Add 1 g of Ni(NO3)2·6H2O, 1 g of Co(NO3)2·6H2O, 2.5 g of urea, and 0.8 g of polyvinylpyrrolidone to the mixed solution of step S1, and stir the mixture at 25°C for 1 hour. Then, add 24 g of anhydrous ethanol and stir for 30 minutes to obtain a mixture. Transfer the mixture to a PTFE-lined autoclave and react at 90°C for 12 hours.

[0054] S3. After the reaction of step S2 is cooled, the product is vacuum filtered, washed with sufficient deionized water, and dried in a vacuum oven at 100° C. for 10 hours to obtain a first solid material;

[0055] S4, adding the first solid material obtained in step S3 to a deionized water solution containing glucose and nano-silica, wherein the mass fraction of glucose is 10%, the mass fraction of nano-silica is 5%, the particle size of the nano-silica used is 10 nm, and the total weight of the deionized water solution containing glucose and nano-silica is 20 g, continuing to dropwise add ammonia water with a mass fraction of 28%, adjusting the pH to 10, and continuously ultrasonically disperse for 2 h at an ultrasonic frequency of 30 kHz, and then removing the deionized water by rotary evaporation at 80° C. to obtain a second solid material;

[0056] S5, calcining the second solid material obtained in step S4 at a heating rate of 10°C / min in an Ar atmosphere, raising the temperature to 800°C, and keeping the temperature for 3 hours, dispersing the calcined product in a potassium hydroxide solution with a concentration of 2 mol / L, heating to 100°C and continuously stirring for 5 hours, filtering the product, washing it with sufficient deionized water, and vacuum drying it to obtain a third solid material;

[0057] S6. Mix the third solid material obtained in step S5 with 2.5 g of melamine, and calcine the mixture in an Ar atmosphere at a heating rate of 5° C. / min, raise the temperature to 900° C., and keep the temperature for 2 h to obtain a zinc-air battery catalyst.

[0058] Comparative Example 1

[0059] The difference between Comparative Example 1 and Example 1 is that all steps S4-S6 are eliminated, and the first solid obtained in step S3 is a zinc-air battery catalyst, which is a double-layered hydroxide synthesized between MXene layers.

[0060] Comparative Example 2

[0061] The difference between Comparative Example 2 and Example 1 is that the addition of glucose in step S4 is eliminated, and the remaining steps are exactly the same as those in Example 1.

[0062] Comparative Example 3

[0063] The difference between Comparative Example 3 and Example 1 is that the addition of nano-silicon dioxide in step S4 is eliminated, and the remaining steps are exactly the same as those in Example 1.

[0064] Scanning electron microscope image

[0065] Figure 2 and Figure 3 This is a scanning electron microscope image of the zinc-air battery catalyst prepared in Example 1 of this application. Figure 2 and Figure 3 It can be clearly seen that a large number of carbon nanotubes have grown on the surface of the zinc-air battery catalyst.

[0066] Figure 4 The energy dispersive X-ray spectroscopy (EDS) of the zinc-air battery catalyst prepared in Example 1 shows that the element distribution diagram shows that C, N, O, Ni, Co and Ti elements are present in Ti3C2T x MXene is evenly distributed in the carbon nanotube (CNT) structure, while Ni and Co elements are concentrated in the nanoparticles.

[0067] Figure 8 The XRD patterns of the present invention are as follows: NiCo-LDH and Comparative Example 1 both exhibit NiCo-LDH characteristic peaks at 11.7°, 34.1°, and 59.3°, corresponding to the (003), (012), and (110) crystal planes of NiCo-LDH crystals, respectively (PCPDF # 38-0715). This indicates that both samples contain NiCo-LDH crystals. It is worth noting that the (003) crystal plane peak intensity of Comparative Example 1 is relatively weak, which may be attributed to the interaction between NiCo-LDH and Ti3C2T x Irregular growth of Ti3C2T with MXene x The atomic layered structure of MXene suppresses the signal. The broad peak at 26.2° in Examples 1-3 corresponds to the (002) crystal plane of graphitic carbon, while the sharp peaks at 44.3°, 51.6°, and 76.1° correspond to the (111), (200), and (220) planes of NiCo alloy (PCPDF # 89-7128, PCPDF #01-1255), respectively. Furthermore, no peaks were observed for the TiO2 phase, indicating the good stability of MXene during the synthesis process.

[0068] ORR performance test

[0069] An electronic balance was used to weigh 4 mg of each zinc-air battery catalyst prepared in Examples 1-3 and Comparative Examples 1-2, and the mixture was mixed with 30 μL of 5 wt% Nafion solution (selected from Shengernuo, the same below), 900 μL of ethanol and 100 μL of deionized water, and ultrasonicated for 25 minutes to obtain a uniform ink-like dispersion; an appropriate amount of the dispersion was dropped onto a glassy carbon electrode and naturally dried at room temperature to prepare a working electrode; all electrochemical tests were performed using a three-electrode system; in the linear sweep voltammetry (LSV) test, glassy carbon was used as the working electrode (with a diameter of 4 mm), the surface of which was coated with the prepared ink-like dispersion, a saturated calomel electrode was used as the reference electrode of the alkaline electrolyte, a carbon rod was used as the counter electrode, and the electrolyte was a 0.1 M KOH solution saturated with N2 / O2. The scan rate during the test was 5 mV s -1 The rotation speed was 1600 rpm and the scanning range was 0.2-1 V (vs. RHE); the scanning speed for cyclic voltammetry (CV) was 50 mV s -1 ; In addition, the reference electrode, counter electrode and electrolyte concentration are the same as the above LSV conditions.

[0070] The RDE test was performed on each sample at 1600 rpm, and the corresponding ORR linear voltammetry (LSV) curves were shown in Figure 2. Figure 5 The half-wave potential (E 1 / 2 ) were 0.85V, 0.78V, 0.79V, 0.63V, 0.75V, and 0.71V, respectively. The catalyst in Example 1 showed a higher half-wave potential (E 1 / 2 ) is 0.85 V vs. RHE and a higher onset potential (Eonset) is 0.93 V vs. RHE. Meanwhile, Example 1 has the highest limiting current density of 5.52 mA cm -2 The difference between Comparative Example 2 and Comparative Example 1 is whether melamine was thermally decomposed (although nano-silicon dioxide was added in Comparative Example 2, the nano-silicon dioxide was etched away by potassium hydroxide later). The results show that the ORR E of Comparative Example 2 is higher than that of Comparative Example 1. 1 / 2 The increase may be due to the conversion of double-layered hydroxide into NiCo alloy after pyrolysis, which increases more reactive sites and constructs a unique 3D MXene structure that significantly increases the specific surface area. The pyrolysis of melamine produces carbon nanotubes, thereby obtaining a more excellent electrocatalytic performance. In addition, the ORR E of Example 1 is greater than that of Comparative Example 2. 1 / 2The increase is due to the carbon layer generated by the pyrolysis of glucose in advance. The outer layer of the NiCo alloy can better combine with the formed carbon nanotubes through the carbon layer, thereby enhancing the interface bonding and conductivity. In Comparative Example 3, after the addition of nano-silica was eliminated, the ORR E of Example 1 was significantly improved. 1 / 2 It shows a decrease. In Example 1, nano-silica acts as a template and is finally etched by potassium hydroxide. The resulting pores allow the NiCo alloy to expose more catalytic active sites and also form a structure with a larger surface area, thus having excellent ORR performance.

[0071] OER performance testing

[0072] 4 mg of each zinc-air battery catalyst prepared in Examples 1-3 and Comparative Examples 1-2 was weighed using an electronic balance and mixed with 30 μL of 5 wt% Nafion solution, 900 μL of ethanol, and 100 μL of deionized water. The mixture was ultrasonicated for 25 minutes to obtain a uniform ink-like dispersion. An appropriate amount of the dispersion was dropped onto a glassy carbon electrode and allowed to dry naturally at room temperature to prepare a working electrode. All electrochemical tests were performed using a three-electrode system. For linear sweep voltammetry (LSV) testing, glassy carbon (4 mm in diameter) was used as the working electrode, coated with the prepared ink-like dispersion. A saturated calomel electrode was used as the reference electrode for the alkaline electrolyte. A carbon rod was used as the counter electrode. The electrolyte was a 1 M KOH solution saturated with nitrogen. The scan rate during the test was 5 mV s. -1 , the scanning range was 1.2–2 V (vs. RHE).

[0073] The OER performance of the catalyst was tested under 1 M KOH conditions. The test results are shown in Figure 2. Figure 6 Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 at 10 mA cm -2 The overpotentials at 308 mV, 370 mV, 358 mV, 437 mV, 401 mV and 419 mV are respectively. Example 1 has a lower overpotential than Examples 2-3 and Comparative Examples 1-3, and thus has a better OER performance.

[0074] Cyclic performance test

[0075] Performance tests were conducted using a homemade zinc-air battery, using a Zn sheet as the anode, carbon paper coated with 12 mg of zinc-air battery catalyst as the cathode, and a mixed aqueous solution of 6 M KOH and 0.2 M Zn(CH3COO)2 as the electrolyte. Typically, a certain amount of catalyst was weighed using an electronic balance and dispersed in a mixture of 90 μL of 5 wt% Nafion solution, 2700 μL of ethanol, and 300 μL of deionized water, followed by sonication for 30 minutes. The resulting homogeneous solution was then sprayed onto the carbon paper surface and allowed to air dry, ensuring a catalyst loading of 2 mg cm -2 .

[0076] Zinc-air battery charge and discharge cycle test is carried out at a certain current value and fixed cycle time. The charge and discharge performance of the battery is judged based on the time and potential graph. Test parameter settings: rest for 10 s, discharge for 5 min, charge for 5 min, current density of 10 mA cm -2 From the cycle time and potential diagram, the longer the cycle time and the smaller the charge and discharge interval, the better the battery performance.

[0077] The ZAB assembled in Example 1 and the ZAB assembled in Comparative Example 2 were tested for cyclic stability. Figure 7 As shown, the ZAB of Example 1 is -2 After 1800 cycles (600 h) at a current density of , it can still maintain good stability, which is better than Comparative Example 2.

[0078] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a zinc-air battery catalyst, characterized in that: The following steps are involved: S1. Disperse MXene powder in deionized water and ultrasonicate for 1 h to obtain a mixed solution; S2. Add nickel nitrate hexahydrate, cobalt nitrate hexahydrate, urea, and polyvinyl pyrrolidone to the mixed solution of step S1, and stir the mixture at 25° C. for 1 hour. Continue to add anhydrous ethanol and stir and mix for 30 minutes to obtain a mixture. Transfer the mixture to a PTFE-lined autoclave and react at 90° C. for 12 hours. S3. After the reaction of step S2 is cooled, the product is vacuum filtered, washed with sufficient deionized water, and dried in a vacuum oven at 100° C. for 10 hours to obtain a first solid material; S4, adding the first solid material obtained in step S3 to a deionized water solution containing glucose and nano-silica, continuing to dropwise add 28% by mass of ammonia water, adjusting the pH to 10, continuously ultrasonically dispersing for 2 h, and then removing the deionized water by rotary evaporation at 80° C. to obtain a second solid material; S5, calcining the second solid material obtained in step S4 at a heating rate of 10°C / min in an Ar atmosphere, raising the temperature to 600-800°C, and keeping the temperature for 3 hours, dispersing the calcined product in a potassium hydroxide solution with a concentration of 2 mol / L, heating to 100°C and continuously stirring for 3-5 hours, filtering the product, washing it with sufficient deionized water, and vacuum drying it to obtain a third solid material; S6. Mixing the third solid material obtained in step S5 with melamine, calcining the mixture in an Ar atmosphere at a heating rate of 5° C. / min, raising the temperature to 700-900° C., and keeping the temperature for 2 hours to obtain a zinc-air battery catalyst.

2. The method for preparing a zinc-air battery catalyst according to claim 1, wherein: The MXene powder used in step S1 is Ti3C2T x , the mass ratio between MXene powder and deionized water is 1:1200.

3. The method for preparing a zinc-air battery catalyst according to claim 1, wherein: The mass ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, urea and polyvinyl pyrrolidone in step S2 to the MXene powder in step S1 is 1:1:(1.5-2.5):(0.3-0.8):0.025; the mass ratio of anhydrous ethanol in step S2 to deionized water in step S1 is 0.8:

1.

4. The method for preparing a zinc-air battery catalyst according to claim 1, wherein: In the deionized water solution of step S4, the mass fraction of glucose is 5-10%, the mass fraction of nano-silicon dioxide is 1-5%, and the particle size of nano-silicon dioxide is 1-10 nm.

5. The method for preparing a zinc-air battery catalyst according to claim 1, wherein: The mass ratio of the deionized water solution containing glucose and nano-silicon dioxide to the sum of the masses of nickel nitrate hexahydrate and cobalt nitrate hexahydrate in step S4 is (5-10):

1.

6. The method for preparing a zinc-air battery catalyst according to claim 1, wherein: In step S6, the mass ratio of melamine to the sum of the masses of nickel nitrate hexahydrate and cobalt nitrate hexahydrate is (1.5-2.5):

1.

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

Images