A non-precious metal oxygen reduction catalyst and its preparation method and application

Abstract

The present invention discloses a non-precious metal oxygen reduction catalyst, a preparation method thereof and an application thereof, belonging to the technical field of metal battery materials. The oxygen reduction catalyst is prepared by a high-temperature pyrolysis process to obtain an S, N co-doped carbon material as the catalyst substrate; then iron tetraphenylporphyrin and iron salts are loaded on the SNC substrate, and then subjected to high-temperature pyrolysis treatment; the prepared catalyst is simultaneously loaded with FeN4 single-atom sites and Fe2O3 nanoparticles on the S, N co-doped carbon material, and the synergistic effect between the FeN4 sites and the Fe2O3 nanoparticles endows the catalyst with excellent oxygen reduction reaction activity and electrochemical stability. The non-precious metal catalyst of the present invention is applied to catalyze the oxygen reduction reaction of the cathode of a metal-air battery, providing an innovative method for the performance regulation of the oxygen reduction reaction catalyst.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal-air battery materials, and in particular relates to a non-precious metal oxygen reduction catalyst and a preparation method and application thereof. Background Art

[0002] The oxygen reduction reaction (ORR) at the cathode of zinc-air batteries plays a crucial role in the overall performance of the device. Currently, platinum-based catalysts are considered to be the most effective materials for catalyzing ORR due to their excellent catalytic activity and stability. However, despite the excellent catalytic properties of platinum-based catalysts, their widespread commercialization still faces major challenges. Since platinum is a rare and expensive precious metal, its main problems are high cost and limited reserves. In addition, resource limitations associated with platinum mining and processing exacerbate sustainable development issues, making large-scale applications economically and environmentally unfeasible. These limitations not only restrict the application of platinum-based catalysts in emerging energy technologies, but also prompt people to look for cost-effective, resource-abundant alternative catalysts that can provide similar or better performance in ORR.

[0003] Among them, metal nitrogen carbon (MNC, M = Fe, Co, Cu, etc.) materials characterized by atomically dispersed M-Nx sites have become highly promising non-precious metal catalysts due to their excellent performance in ORR. Although great progress has been made in the research of single-atom catalysts, the density of active sites in single-atom catalysts is significantly lower than that of traditional nanoparticle catalysts, which limits their overall activity per unit mass in practical applications.

[0004] CN115064704A discloses a porous carbon catalyst doped with nitrogen and sulfur and loaded with single iron atoms and a preparation method thereof. Although the nitrogen and sulfur co-doped single iron atom catalyst optimizes the electronic structure of the Fe single atom active site (FeN4) by sulfur doping, it does not further introduce other active sites to finely control the electronic environment of the Fe single atom to achieve the best balance between adsorption and desorption behavior during the catalytic process, thereby further improving the activity and kinetic performance of the catalyst. In addition, the multi-electron transfer ability of the single atom site in ORR is also limited, which affects the reaction kinetics and overall catalytic efficiency.

[0005] CN111342057A discloses a preparation method and application of a metalloporphyrin-modified sulfur-doped reduced graphene oxide electrocatalyst. Although the catalyst introduces an electronic regulation mechanism through sulfur doping, the regulation is limited to a simple synergistic effect between the substrate and the metalloporphyrin, and the catalytic activity is low. Summary of the invention

[0006] In order to solve the above problems, a non-precious metal oxygen reduction catalyst and a preparation method and application thereof are provided. The catalyst uses S and N co-doped carbon material as a carrier, on which FeN4 single atom sites and Fe2O3 nanoparticles are loaded simultaneously. The coordinated effect of FeN4 single atoms and Fe2O3 nanoparticles improves the reaction activity and stability of the catalyst in the oxygen reduction reaction.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] A method for preparing a non-precious metal oxygen reduction catalyst comprises the following preparation steps:

[0009] (1) dissolving a sulfur-containing precursor and a nitrogen-containing precursor in a solvent, then adding a carbon material, stirring the mixture evenly, filtering, drying, and then pyrolyzing the mixture at a high temperature under an inert atmosphere to obtain a S and N co-doped carbon material;

[0010] (2) dissolving tetraphenylporphyrin iron and iron salt in an organic solvent, adding a certain amount of the S and N co-doped carbon material obtained in step (1), heating and stirring for a period of time, filtering, drying and high-temperature pyrolysis to obtain the non-precious metal oxygen reduction catalyst;

[0011] Wherein, in step (1), the molar ratio of carbon to nitrogen and sulfur elements is (10-50): (1-3): 1; in step (2), the mass ratio of the S and N co-doped carbon material added to the mass ratio of tetraphenylporphyrin iron is 1: (1-2), and the molar ratio of tetraphenylporphyrin iron to iron in the iron salt is (4-12): 1.

[0012] The preparation method of the present invention uses carbon material as a substrate, adopts a high-temperature pyrolysis process to prepare an S, N co-doped carbon material (SNC) as a catalyst substrate, and then loads tetraphenylporphyrin iron and iron salt on the SNC material, and then undergoes high-temperature pyrolysis treatment to prepare a new catalyst that simultaneously loads FeN4 single atom sites and Fe2O3 nanoparticles on the S, N co-doped carbon material. The doping of heteroatom S can create defects in the catalyst substrate, increase the specific surface area of ​​the catalyst, and facilitate the exposure of active sites, while the synergistic effect of the FeN4 single atom sites and the Fe2O3 nanoparticles enhances the catalytic activity and stability of the catalyst.

[0013] In the present invention, by adjusting the addition ratio of tetraphenylporphyrin iron and iron salt, the aggregation of Fe single atoms during high-temperature pyrolysis is prevented, thereby improving its stability and catalytic activity; ensuring that Fe2O3 nanoparticles are generated in an appropriate amount to avoid excessive effects on specific surface area and electronic structure optimization; and optimizing the synergistic effect of single atoms and nanoparticles, so that the catalyst has high activity and excellent long-term stability in the oxygen reduction reaction.

[0014] The present invention is further configured such that the sulfur-containing precursor is selected from at least one of thiourea, elemental sulfur or diphenyl disulfide; the nitrogen-containing precursor is selected from at least one of thiourea, melamine or urea, the carbon material is selected from at least one of carbon black, graphite or carbon nanotubes, and the iron salt is selected from at least one of ferrous chloride, ferrous acetate or ferric chloride.

[0015] The present invention is further configured such that, in step (1), the molar ratio of carbon to nitrogen and sulfur elements is (15-45):(1-3):1.

[0016] The present invention is further configured such that, in step (1), the sulfur-containing precursor and the nitrogen-containing precursor are both thiourea, and the molar ratio of carbon to nitrogen and sulfur elements is (15-45):2:1.

[0017] The present invention is further configured such that, in step (1), the temperature of the high temperature pyrolysis is 600-800° C. and the time is 0.5-2 h.

[0018] The present invention is further configured such that, in step (2), the organic solvent is selected from one or more of dichloromethane and acetonitrile.

[0019] The present invention is further configured such that, in step (2), the molar ratio of tetraphenylporphyrin iron to iron in the iron salt is (4-10):1.

[0020] The present invention is further configured such that, in step (2), the temperature of heating and stirring is 70-90° C., and the stirring time is 12-24 hours.

[0021] The present invention is further configured such that, in step (2), the high temperature pyrolysis temperature is 700° C. to 900° C., and the pyrolysis time is 0.1 to 1.0 h.

[0022] The second aspect of the present invention provides a non-precious metal oxygen reduction catalyst prepared according to the above preparation method, wherein the catalyst uses S and N co-doped carbon as a carrier, on which FeN4 single atom sites and Fe2O3 nanoparticles are loaded.

[0023] The third aspect of the present invention is to provide the use of the non-precious metal oxygen reduction catalyst prepared by the above preparation method in a zinc-air battery for cathode oxygen reduction reaction.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The non-precious metal catalyst prepared by the present invention has the advantages of both single-atom catalysts and metal nanoparticle catalysts, overcoming the defects of single-atom catalysts that they have fewer active sites and are easily coated by the substrate. Defects are introduced into the catalyst by S doping, thereby increasing the specific surface area of ​​the catalyst. At the same time, the catalytic activity of the catalyst is improved through the synergistic effect between the metal single-atom sites and the nanoparticle species.

[0026] (2) The non-precious metal catalyst of the present invention has excellent catalytic activity and electrochemical stability in oxygen reduction reaction. The non-precious metal catalyst of the present invention has great application prospects in the field of metal-air batteries and provides a new method for regulating oxygen reduction reaction catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the process of preparing a non-precious metal oxygen reduction catalyst according to the present invention.

[0028] Figure 2 is the XRD pattern of Example 1 prepared in the present invention.

[0029] Figure 3 It is the Raman graph of Example 1 prepared by the present invention.

[0030] Figure 4 is a SEM image of Example 1 prepared in the present invention.

[0031] Figure 5 It is the TEM image and electron diffraction pattern of Example 1 prepared by the present invention.

[0032] Figure 6 It is the TEM elemental analysis diagram of Example 1 prepared by the present invention. DETAILED DESCRIPTION

[0033] The present invention is described in detail and completely with specific embodiments and in conjunction with the accompanying drawings. It should be understood that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of the present invention.

[0034] In the following examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if no manufacturer is specified, are conventional products that can be purchased through commercial channels.

[0035] refer to Figure 1The present invention provides a method for preparing a non-precious metal oxygen reduction catalyst, comprising the following preparation steps: (1) dissolving a sulfur-containing precursor and a nitrogen-containing precursor in a solvent, then adding a carbon material, stirring the mixture evenly, filtering and drying the mixture, and then performing high-temperature pyrolysis under an inert atmosphere to obtain a S and N co-doped carbon material;

[0036] (2) dissolving tetraphenylporphyrin iron and iron salt in an organic solvent, adding a certain amount of the S and N co-doped carbon material obtained in step (1), heating and stirring for a period of time, filtering, drying and high-temperature pyrolysis to obtain the non-precious metal oxygen reduction catalyst;

[0037] Wherein, in step (1), the molar ratio of carbon to nitrogen and sulfur elements is (10-50): (1-3): 1; in step (2), the mass ratio of the added S and N co-doped carbon material to tetraphenylporphyrin iron is 1: (1-2), for example, 1: 1, 1: 1.5 or 1: 2; the molar ratio of tetraphenylporphyrin iron to iron in the iron salt is (4-12): 1;

[0038] The sulfur-containing precursor is selected from at least one of thiourea, elemental sulfur or diphenyl disulfide, the nitrogen-containing precursor is selected from at least one of thiourea, melamine or urea, the carbon material is selected from at least one of carbon black, graphite or carbon nanotubes, and the iron salt is selected from at least one of ferrous chloride, ferrous acetate or ferric chloride.

[0039] In one embodiment of the present invention, in step (1), the molar ratio of carbon to nitrogen and sulfur is (15-45): (1-3):1.

[0040] In one embodiment of the present invention, in step (1), the sulfur-containing precursor and the nitrogen-containing precursor are both thiourea, and the molar ratio of carbon to nitrogen and sulfur elements is (15-45):2:1; for example, 15:2:1, 30:2:1 or 45:2:1.

[0041] In one embodiment of the present invention, in step (1), the sulfur-containing precursor and the nitrogen-containing precursor are both thiourea, and the concentration of the solution after thiourea is dissolved in the solvent is 0.005 mol / L~0.05 mol / L; preferably 0.006 mol / L~0.03 mol / L.

[0042] In one embodiment of the present invention, in step (1), the high temperature pyrolysis temperature is 600-800° C. and the time is 0.5-2 h.

[0043] In one embodiment of the present invention, in step (2), the organic solvent is selected from dichloromethane and / or acetonitrile; preferably, it is a mixed solvent of dichloromethane and acetonitrile, and the volume ratio of dichloromethane to acetonitrile is (2:3) to (3:2), for example, the volume ratio of dichloromethane to acetonitrile is 2:3, 3:2 or 1:1.

[0044] In one embodiment of the present invention, in step (2), the molar ratio of tetraphenylporphyrin iron to iron in the iron salt is (4-10):1, for example, 4:1, 4.25:1, 5:1, 6:1, 7.4:1, 8:1, 9:1, 9.6:1 or 10:1.

[0045] In one embodiment of the present invention, in step (2), the heating and stirring temperature is 70-90°C, and the stirring time is 12-24 hours; the high-temperature pyrolysis temperature is 700-900°C, and the pyrolysis time is 0.1-1.0 hour.

[0046] The non-precious metal oxygen reduction catalyst prepared according to the preparation method uses S and N co-doped carbon as a carrier, on which FeN4 single atom sites and Fe2O3 nanoparticles are loaded. Example 1

[0047] A non-precious metal oxygen reduction catalyst, the preparation method of which specifically comprises the following preparation steps:

[0048] (1) 50 mg of thiourea was dissolved in 50 mL of ethanol reagent, and then 240 mg of carbon black (molar mass 12.01 g / mol) was added. The resulting mixture was stirred at room temperature for 12 h, and then the solid phase was obtained by filtration. The solid phase was placed in a vacuum drying oven and dried at 60 °C for 12 h. After being fully dried, the sample was heated to 800 °C at a heating rate of 5 °C / min in an argon atmosphere and pyrolyzed for 1 h to obtain S, N co-doped carbon material.

[0049] (2) 50 mL of dichloromethane and 50 mL of acetonitrile were thoroughly mixed in a flask, and then 120 mg of tetraphenylporphyrin iron and 8 mg of ferrous chloride tetrahydrate were added to the flask. After stirring to fully dissolve, 80 mg of the carbon material SNC prepared in step (1) was added. After heating and stirring at 80 °C for 12 h, the solid phase was obtained by filtration. After drying in a vacuum drying oven, the temperature was increased to 800 °C at a heating rate of 5 °C / min under an argon atmosphere, and pyrolysis was performed for 0.5 h to obtain the final catalyst FeN4-Fe2O3@SNC, which was marked as X1.

[0050] The structure and morphology of catalyst X1 were systematically analyzed by various characterization methods. Figure 2As shown in the figure, the characteristic diffraction peak of catalyst X1 in the XRD spectrum is highly matched with the characteristic peak of the Fe2O3 crystal phase, indicating the presence of Fe2O3 nanoparticles in the catalyst. Raman spectrum ( Figure 3 ) shows characteristic peaks of D band and G band, and the D / G peak intensity ratio (I_D / I_G) is 1.07, indicating that the catalyst has a high structural defect, which is conducive to the adsorption of oxygen and the catalytic reaction. SEM imaging ( Figure 4 ) revealed that catalyst X1 presents a stacked carbon nanolayer morphology, providing abundant exposed interfaces for the loading of Fe-N4 active centers and Fe2O3 nanoparticles. High-resolution transmission electron microscopy (HRTEM) and electron diffraction patterns ( Figure 5 ) further confirmed the lattice fringes of Fe2O3 and verified the existence of Fe2O3 nanoparticles. Element Mapping Analysis ( Figure 6 ) clearly shows the distribution of elements such as C, N, O, S, and Fe in the catalyst. These characterization results jointly confirm that catalyst X1 improves the catalytic performance of oxygen reduction reaction (ORR) through the synergistic effect of single-atom Fe-N4 active centers and Fe2O3 nanoparticles. Example 2

[0051] A non-precious metal oxygen reduction catalyst, the preparation method of which specifically comprises the following preparation steps:

[0052] (1) 100 mg of thiourea was dissolved in 50 mL of ethanol reagent, and then 240 mg of carbon black was added. The resulting mixture was stirred at room temperature for 12 h, and then the solid phase was obtained by filtration. The solid phase was placed in a vacuum drying oven and dried at 60 °C for 12 h. After being fully dried, the sample was heated to 800 °C at a heating rate of 5 °C / min in an argon atmosphere and pyrolyzed for 1 h to obtain S, N co-doped carbon material.

[0053] (2) 50 mL of dichloromethane and 50 mL of acetonitrile were thoroughly mixed in a flask, and then 120 mg of tetraphenylporphyrin iron and 8 mg of ferrous chloride tetrahydrate were added to the flask. After stirring to fully dissolve, 80 mg of the carbon material prepared in step (1) was added. After heating and stirring at 80°C for 12 h, the solid phase was obtained by filtration. After drying in a vacuum drying oven, the temperature was increased to 800°C at a heating rate of 5°C / min under an argon atmosphere, and pyrolysis was performed for 0.5 h to obtain the final catalyst, which was marked as X2. Example 3

[0054] A non-precious metal oxygen reduction catalyst, the preparation method of which specifically comprises the following preparation steps:

[0055] (1) 35 mg of thiourea was dissolved in 50 mL of ethanol reagent, and then 240 mg of carbon black was added. The resulting mixture was stirred at room temperature for 12 h, and then the solid phase was obtained by filtration. The solid phase was placed in a vacuum drying oven and dried at 60 °C for 12 h. After being fully dried, the sample was heated to 800 °C at a heating rate of 5 °C / min in an argon atmosphere and pyrolyzed for 1 h to obtain S, N co-doped carbon material.

[0056] (2) 50 mL of dichloromethane and 50 mL of acetonitrile were thoroughly mixed in a flask, and then 120 mg of tetraphenylporphyrin iron and 8 mg of ferrous chloride tetrahydrate were added to the flask. After stirring to fully dissolve, 80 mg of the carbon material prepared in step (1) was added. After heating and stirring at 80°C for 12 h, the solid phase was obtained by filtration. After drying in a vacuum drying oven, the temperature was increased to 800°C at a heating rate of 5°C / min under an argon atmosphere, and pyrolysis was performed for 0.5 h to obtain the final catalyst labeled as X3. Example 4

[0057] The preparation steps of the catalyst in this embodiment are basically the same as those in Example 1, except that the mass ratio of tetraphenylporphyrin iron to ferrous chloride tetrahydrate is different, specifically: 50 mL of dichloromethane and 50 mL of acetonitrile are fully mixed in a flask, then 120 mg of tetraphenylporphyrin iron and 4.5 mg of ferrous chloride tetrahydrate are added to the flask, stirred to fully dissolve, and then 80 mg of the prepared carbon material is added. After heating and stirring at 80°C for 12 h, a solid phase is obtained by suction filtration, placed in a vacuum drying oven for drying, and then heated to 800°C at a heating rate of 5°C / min under an argon atmosphere, and pyrolyzed for 0.5 h to obtain a final catalyst marked as X4. Example 5

[0058] The preparation steps of the catalyst in this embodiment are basically the same as those in Example 1, except that the mass ratio of tetraphenylporphyrin iron to ferrous chloride tetrahydrate is different, specifically:

[0059] 50 mL of dichloromethane and 50 mL of acetonitrile were fully mixed in a flask, and then 120 mg of tetraphenylporphyrin iron and 3.5 mg of ferrous chloride tetrahydrate were added to the flask, stirred to fully dissolve, and then 80 mg of the prepared carbon material was added. After heating and stirring at 80°C for 12 h, the solid phase was obtained by filtration, placed in a vacuum drying oven for drying, and then heated to 800°C at a heating rate of 5°C / min under an argon atmosphere, and pyrolyzed for 0.5 h to obtain the final catalyst marked as X5. Example 6

[0060] A non-precious metal oxygen reduction catalyst, the preparation method of which specifically comprises the following preparation steps:

[0061] (1) 21 mg of elemental sulfur and 27 mg of melamine were dissolved in a mixture of 25 mL of ethanol and 25 mL of petroleum ether, and then 240 mg of graphite (molar mass: 12.01 g / mol) was added. The resulting mixture was stirred at room temperature for 12 h, and then the solid phase was obtained by filtration. The solid phase was placed in a vacuum drying oven and dried at 60 °C for 12 h. After being fully dried, the sample was heated to 800 °C at a heating rate of 5 °C / min in an argon atmosphere and pyrolyzed for 1 h to obtain S, N co-doped carbon material.

[0062] (2) 50 mL of dichloromethane and 50 mL of acetonitrile were thoroughly mixed in a flask, and then 120 mg of tetraphenylporphyrin iron and 7 mg of ferrous acetate were added to the flask. After stirring to fully dissolve, 80 mg of the carbon material SNC prepared in step (1) was added. After heating and stirring at 80 °C for 12 h, the solid phase was obtained by filtration. After drying in a vacuum drying oven, the temperature was increased to 800 °C at a heating rate of 5 °C / min under an argon atmosphere, and pyrolysis was performed for 0.5 h to obtain the final catalyst FeN4-Fe2O3@SNC, which was marked as X6′. Example 7

[0063] A non-precious metal oxygen reduction catalyst, the preparation method of which specifically comprises the following preparation steps:

[0064] (1) 72 mg of diphenyl disulfide and 39 mg of urea were dissolved in 50 mL of ethanol reagent, and then 240 mg of carbon nanotubes (molar mass 12.01 g / mol) were added. The resulting mixture was stirred at room temperature for 12 h, and then the solid phase was obtained by filtration. The solid phase was placed in a vacuum drying oven and dried at 60 °C for 12 h. After being fully dried, the sample was heated to 800 °C at a heating rate of 5 °C / min in an argon atmosphere and pyrolyzed for 1 h to obtain S, N co-doped carbon material.

[0065] (2) 50 mL of dichloromethane and 50 mL of acetonitrile were thoroughly mixed in a flask, and then 120 mg of tetraphenylporphyrin iron and 6.53 mg of ferric chloride were added to the flask. After stirring to fully dissolve, 80 mg of the carbon material SNC prepared in step (1) was added. After heating and stirring at 80 °C for 12 h, the solid phase was obtained by filtration. After drying in a vacuum drying oven, the temperature was increased to 800 °C at a heating rate of 5 °C / min under an argon atmosphere, and pyrolysis was performed for 0.5 h to obtain the final catalyst FeN4-Fe2O3@SNC, which was marked as X7′.

[0066] Comparative Example 1

[0067] The preparation of the catalyst of this comparative example is based on the following preparation steps:

[0068] (1) 13.8 mg of melamine was dissolved in 50 mL of ethanol reagent, and then 240 mg of carbon black was added. The resulting mixture was stirred at room temperature for 12 h, and then the solid phase was obtained by filtration. The solid phase was placed in a vacuum drying oven and dried at 60 °C for 12 h. After being fully dried, the sample was heated to 800 °C at a heating rate of 5 °C / min in an argon atmosphere and pyrolyzed for 1 h to obtain a N-doped carbon material.

[0069] (2) 50 mL of dichloromethane and 50 mL of acetonitrile were thoroughly mixed in a flask, and then 120 mg of tetraphenylporphyrin iron and 8 mg of ferrous chloride tetrahydrate were added to the flask. After stirring to fully dissolve, 80 mg of the carbon material prepared in step (1) was added. After heating and stirring at 80°C for 12 h, the solid phase was obtained by filtration. After drying in a vacuum drying oven, the temperature was increased to 800°C at a heating rate of 5°C / min under an argon atmosphere, and pyrolysis was performed for 0.5 h to obtain the final catalyst labeled X6.

[0070] Comparative Example 2

[0071] The preparation of the catalyst of this comparative example is based on the following preparation steps:

[0072] (1) 50 mg of thiourea was dissolved in 50 ml of ethanol reagent, and then 240 mg of carbon black was added. The resulting mixture was stirred at room temperature for 12 h, and then the solid phase was obtained by filtration. The solid phase was placed in a vacuum drying oven and dried at 60 °C for 12 h. After being fully dried, the sample was heated to 700 °C at a heating rate of 5 °C / min in an argon atmosphere and pyrolyzed for 1 h to obtain S, N co-doped carbon material.

[0073] (2) 50 mL of dichloromethane and 50 mL of acetonitrile were thoroughly mixed in a flask, and then 120 mg of tetraphenylporphyrin iron was added to the flask. After stirring to fully dissolve it, 80 mg of the carbon material prepared in step (1) was added. After heating and stirring at 80 °C for 12 h, the solid phase was obtained by filtration. After drying in a vacuum drying oven, the temperature was increased to 800 °C at a heating rate of 5 °C / min under an argon atmosphere, and pyrolysis was performed for 0.5 h to obtain the final catalyst labeled X7.

[0074] Comparative Example 3

[0075] The preparation of the catalyst of this comparative example is based on the following preparation steps:

[0076] (1) 50 mg of thiourea was dissolved in 50 ml of ethanol reagent, and then 240 mg of carbon black was added. The resulting mixture was stirred at room temperature for 12 h, and then the solid phase was obtained by filtration. The solid phase was placed in a vacuum drying oven and dried at 60 °C for 12 h. After being fully dried, the sample was heated to 800 °C at a heating rate of 5 °C / min in an argon atmosphere and pyrolyzed for 1 h to obtain S, N co-doped carbon material.

[0077] (2) 50 mL of dichloromethane and 50 mL of acetonitrile were thoroughly mixed in a flask, and then 8 mg of ferrous chloride tetrahydrate was added to the flask. After stirring to fully dissolve it, 80 mg of the carbon material prepared in step (1) was added. After heating and stirring at 80 °C for 12 h, the solid phase was obtained by filtration. After drying in a vacuum drying oven, the temperature was increased to 800 °C at a heating rate of 5 °C / min under an argon atmosphere, and pyrolysis was performed for 0.5 h to obtain the final catalyst labeled X8.

[0078] Performance Test 1

[0079] The non-precious metal oxygen reduction catalysts prepared in the above examples and comparative examples were subjected to the following electrochemical tests in a 0.1 M KOH solution using a three-electrode system. The half-wave potential (E 1 / 2 ) and the number of transferred electrons (n) are used to evaluate the ORR catalytic activity of the catalyst. The glassy carbon electrode is the working electrode, the mercury / mercury oxide electrode is the reference electrode, and the carbon rod is the counter electrode. The electrochemical test results of the catalyst are shown in Table 1.

[0080] Table 1 Electrochemical tests of catalysts

[0081]

[0082] From the results in Table 1, it can be seen that the non-precious metal catalyst prepared in the present invention has significantly higher half-wave potential and number of transferred electrons under alkaline conditions than the catalysts prepared in Comparative Examples 1 to 3. This indicates that the catalyst prepared in the present invention has excellent ORR catalytic activity under alkaline conditions, among which No. X1 has the highest half-wave potential and the number of transferred electrons is closest to 4, showing high ORR catalytic activity and 4-electron selectivity.

[0083] Performance Test 2

[0084] The non-precious metal oxygen reduction catalysts prepared in the above embodiments and comparative examples were subjected to the following electrochemical tests in a 0.1 M KOH solution through a three-electrode system, and the ORR catalytic activity of the catalysts was evaluated by a 60 h constant voltage test (IT) and a 10,000 cycle accelerated durability test (ADT). The glassy carbon electrode was the working electrode, the mercury / mercury oxide electrode was the reference electrode, and the carbon rod was the counter electrode. The electrochemical test results of the catalysts are shown in Table 2.

[0085] Table 2 Electrochemical tests of catalysts

[0086]

[0087] From the results in Table 2, it can be seen that the non-precious metal catalyst prepared in the present invention has significantly better stability than that of Comparative Examples 1 to 3. Among them, after a 60-h constant voltage test, the current of No. X1 can still maintain 99.8 of the initial current, and its half-wave potential only drops by 6 mV after 10,000 cycles of accelerated endurance, indicating that it has the best stability.

[0088] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a non-precious metal oxygen reduction catalyst, characterized in that: The steps include: (1) dissolving a sulfur-containing precursor and a nitrogen-containing precursor in a solvent, then adding a carbon material, stirring the mixture evenly, filtering, drying, and then pyrolyzing the mixture at a high temperature under an inert atmosphere to obtain a S- and N-co-doped carbon material; (2) dissolving tetraphenylporphyrin iron and iron salt in an organic solvent, adding a certain amount of S and N co-doped carbon material obtained in step (1), heating and stirring for a period of time, filtering, drying and high-temperature pyrolysis to obtain the non-precious metal oxygen reduction catalyst; wherein, In step (1), the molar ratio of carbon to nitrogen and sulfur is (10-50): (1-3): 1, and the carbon material is selected from at least one of carbon black, graphite or carbon nanotubes; In step (2), the mass ratio of the added S, N co-doped carbon material to tetraphenylporphyrin iron is 1: (1-2); the molar ratio of tetraphenylporphyrin iron to the iron in the iron salt is (4-12): 1; in step (2), the temperature of heating and stirring is 70-90°C.

2. The preparation method according to claim 1, characterized in that: The sulfur-containing precursor is selected from at least one of thiourea, elemental sulfur or diphenyl disulfide, the nitrogen-containing precursor is selected from at least one of thiourea, melamine or urea, and the iron salt is selected from at least one of ferrous chloride, ferrous acetate or ferric chloride.

3. The preparation method according to claim 1, characterized in that: In step (1), the high temperature pyrolysis temperature is 600-800° C. and the time is 0.5-2 h.

4. The preparation method according to claim 1, characterized in that: In step (2), the high temperature pyrolysis temperature is 700°C to 900°C, and the pyrolysis time is 0.1 to 1.0h.

5. A non-precious metal oxygen reduction catalyst, characterized in that The catalyst is prepared by the preparation method described in any one of claims 1 to 4, wherein the catalyst uses S and N co-doped carbon as a carrier, on which FeN4 single atom sites and Fe2O3 nanoparticles are loaded.

6. A use of the non-precious metal oxygen reduction catalyst as claimed in claim 5, characterized in that: Used in the cathode oxygen reduction reaction in zinc-air batteries.

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