Zif-derived non-noble metal electrocatalysts and methods of making the same

Abstract

The application relates to the field of fuel cells, in particular to a ZIF-derived non-noble metal electrocatalyst and a preparation method thereof. H3BTT*2HC1 and chloroform are added into a container, m-chloroperbenzoic acid is added dropwise to obtain a first liquid; the container is sealed, the first liquid is preserved at 40 DEG C to 60 DEG C and stirred, and after natural cooling, toluene is added, the first liquid is stirred, and ultraviolet rays are irradiated for several hours to obtain a second liquid; the container is opened, pyridine and ammonium carbonate are added, and stirring is carried out to obtain a third liquid; the third liquid is preserved at -70 DEG C to -80 DEG C, mixed gas of ozone and oxygen is bubbled in, pure oxygen is bubbled in, and nitrogen is bubbled in to obtain a fourth liquid; the fourth liquid is preserved at 85 DEG C to 95 DEG C and stirred, and filtration and drying are carried out to obtain a first powder; the first powder and anhydrous ferrous chloride are added into a mixed solution of dimethylformamide and dimethyl sulfoxide, preservation and stirring are carried out, filtration is carried out, and drying is carried out to obtain a second powder; the second powder is preserved at 700 DEG C to 1000 DEG C to obtain the ZIF-derived non-noble metal electrocatalyst, and the ZIF-derived non-noble metal electrocatalyst can reduce the cost of a polymer electrolyte membrane fuel cell.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fuel cells, and particularly relates to a ZIF-derived non-noble metal electrocatalyst and a preparation method thereof. BACKGROUND

[0002] In the prior art, polymer electrolyte membrane fuel cells (PEMFCs) are considered to be the most promising alternative to internal combustion engines. Unlike internal combustion engines, PEMFCs provide high energy conversion efficiency and power density at relatively low operating temperatures, and zero or low greenhouse gas emissions. Compared with platinum (Pt)-based electrocatalysts, non-noble metal-based electrocatalysts have attracted widespread attention due to their lower cost, and the development of high-performance non-noble metal electrocatalysts for cathode oxygen reduction reactions (ORR) is crucial for the large-scale commercial application of PEMFCs.

[0003] Among various non-noble metal electrocatalysts, transition metal-nitrogen-carbon (M-N-C) catalysts are the most competitive, and such catalysts have simple and flexible synthesis methods, low cost, and excellent ORR catalytic activity under acidic conditions. In order to obtain high-performance non-noble metal electrocatalysts, it is crucial to regulate the active site density and framework structure during synthesis. Nitrogen is an important component of the active site, and the framework structure includes the structural position of transition metal and nitrogen, as well as the structure of the carbon support. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes a ZIF-derived non-noble metal electrocatalyst and a preparation method thereof, which can reduce the cost of PEMFCs.

[0005] According to the first aspect of the embodiment of the ZIF-derived non-noble metal electrocatalyst, S1: H3BTT·2HCl and chloroform are added to a container under a protective atmosphere, and m-chloroperbenzoic acid is added dropwise into the container to obtain a first liquid; S2: the container is sealed, and the first liquid is incubated at 40-60 DEG C and stirred for 15-20 hours, and after natural cooling, toluene is added, the first liquid is stirred, and ultraviolet light of 275-320 nm is irradiated for 3-5 hours to obtain a second liquid; S3: the container is opened, pyridine and ammonium carbonate are added, and the third liquid is stirred to obtain a third liquid; S4: the third liquid is incubated at -70 DEG C to -80 DEG C, and ozone and oxygen mixed gas are bubbled in turn for 5-15 minutes, pure oxygen is bubbled in for 1-5 minutes, and nitrogen is bubbled in for 1-5 minutes to obtain a fourth liquid; S5: the fourth liquid is incubated at 85-95 DEG C and stirred for 12-36 hours, and the first powder is obtained by filtration and drying; S1 to S5 mainly convert the carbon atoms in H3BTT·2HCl into nitrogen atoms, and the nitrogen atoms are part of the active sites and play a key role in the catalyst activity. First, the oxidative restructuring of the benzene ring produces an open-ring intermediate with an electron affinity site, which is ready for ring closure and carbon-based leaving groups, in situ generates an intermediate with two carbonyl groups, activates to form a carboxylate leaving group, and at the same time promotes the condensation of ammonia and finally obtains the product, and in one step, the benzene ring with different positions and different groups is converted into the corresponding pyridine derivative, thereby replacing the carbon atom with a nitrogen atom. This replacement method can control the amount of nitrogen doping and effectively increase the content of nitrogen elements. In addition, the pyridine derivative has multiple types of nitrogen atoms, including nitrogen atoms located at the edge of the carbon plane, and each nitrogen atom is connected to two carbon atoms and donates one p electron to the aromatic p system, and the nitrogen atom type connected to three carbon atoms, thereby increasing the efficient electrocatalytic activity.

[0006] S6: Under a protective atmosphere, the first powder and anhydrous ferrous chloride are added to a mixture of dimethylformamide and dimethyl sulfoxide, and incubated at 100-150 DEG C for 12-36 hours with stirring, filtered, and dried to obtain a second powder; This step is to synthesize a metal-organic material similar to ZIF, which has been centered on chloride and combined with nitrogen atoms, so that high-density nitrogen atom active sites are uniformly distributed in the octahedron containing iron ions, and adjacent octahedral spaces are shared to form a cubic framework.

[0007] S7: Under a protective atmosphere, the second powder is incubated at 700-1000 DEG C for 60-180 minutes to obtain a ZIF-derived non-noble metal electrocatalyst. This step is to convert the organic ligand into a carbon carrier by thermal cracking, forming a porous carbon skeleton, not only improving the electronic conductivity, but also increasing the degree of graphitization due to pyrolysis, promoting the formation of nitrogen atom active sites at the edge of the carbon plane, promoting the formation of iron-nitrogen-carbon active sites, and improving the catalytic activity.

[0008] According to the preparation method of the ZIF-derived non-noble metal electrocatalyst, at least the following beneficial effects are achieved:

[0009] By converting the carbon atoms in H3BTT·2HCl into nitrogen atoms, the carbon atoms are replaced by nitrogen atoms. This replacement can control the amount of nitrogen doping and effectively increase the content of nitrogen elements. Nitrogen atoms are part of the active sites, and the ordered lattice of graphitized carbon can promote the formation of active sites generated by nitrogen doping, thereby increasing the efficient electrocatalytic activity. Further synthesis of porous metal organic framework materials, in which metal ions or metal clusters are connected together by organic linkers, can provide a high density of active sites uniformly distributed in the framework. By thermal decomposition of the organic ligand into a carbon carrier, iron / nitrogen / carbon active sites are formed, so that active metal-containing substances and carbon carriers can be formed at the same time. The porosity of the carbon produced by thermal cracking can ensure the accessibility of the active sites to the reactants and products related to ORR.

[0010] According to some embodiments of the present application, S7: the second powder is kept at 700-1000℃ for 90 minutes under a protective atmosphere to obtain a third powder; further comprising: S8: adding the third powder to a sulfuric acid solution, ultrasonicating for 1-3 hours, filtering, washing, and drying to obtain the ZIF-derived non-noble metal electrocatalyst. The chemical acid washing treatment is mainly to dissolve unstable iron atoms to avoid contaminating the proton exchange membrane during the catalytic reaction, which is beneficial to ensure the service life of the fuel cell.

[0011] According to some embodiments of the present application, the concentration of the sulfuric acid solution is 0.5-2 mol / L.

[0012] According to some embodiments of the present application, the mass ratio of the first powder to anhydrous ferrous chloride is 1:3-4.

[0013] According to some embodiments of the present application, the mass ratio of H3BTT·2HCl, meta-chloroperoxybenzoic acid, pyridine, and ammonium carbonate is 250-350:300-400:0.5-2:500-600.

[0014] According to some embodiments of the present application, the concentration of ozone in the ozone and oxygen mixed gas is 20%-40%.

[0015] According to some embodiments of the present application, S4: the container is placed in an acetone, diethyl ether, or ethyl acetate bath, and dry ice or liquid nitrogen is added to keep the third liquid at (-70)-(-80)℃, ozone and oxygen mixed gas is bubbled in for 5-15 minutes, pure oxygen is bubbled in for 1-5 minutes, and nitrogen gas is bubbled in for 1-5 minutes to obtain a fourth liquid.

[0016] According to some embodiments of the present application, S4: the third liquid is kept at -78 DEG C, and ozone and oxygen mixed gas is bubbled in for 10 minutes, pure oxygen is bubbled in for 3 minutes, and nitrogen is bubbled in for 3 minutes, to obtain a fourth liquid.

[0017] According to some embodiments of the present application, in S2, the wavelength of the ultraviolet light is 390 nanometers.

[0018] According to some embodiments of the present application, a ZIF-derived non-noble metal electrocatalyst prepared by the above ZIF-derived non-noble metal electrocatalyst is provided.

[0019] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0020] The present application will be further described below in conjunction with the accompanying drawings and embodiments, in which:

[0021] Figure 1 A flowchart of the ZIF-derived non-noble metal electrocatalyst of the embodiments of the present application is shown in the figure.

[0022] Figure 2 A transmission electron microscope (TEM) diagram of the preparation method of the ZIF-derived non-noble metal electrocatalyst of Embodiment 1 of the present application is shown in the figure.

[0023] Figure 3 A cyclic voltammetry (CV) test diagram of the ZIF-derived non-noble metal electrocatalyst prepared in Embodiment 1 of the present application under acidic conditions is shown in the figure. DETAILED DESCRIPTION

[0024] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, in which the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0025] In the description of the present application, the meaning of several is more than one, the meaning of multiple is more than two, greater than, less than, more than, etc. are understood as not including the number, above, below, etc. are understood as including the number. If it is described that the first, the second is only used to distinguish the technical features for the purpose, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the sequence of indicated technical features.

[0026] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "illustrative embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any appropriate manner in one or more embodiments or examples.

[0027] The following is a further description of the present application, rather than a limitation of the present application.

[0028] Embodiment 1

[0029] As shown in the following, the present embodiment prepared a ZIF-derived non-noble metal electrocatalyst, and the specific process is as follows: Figure 1

[0030] (1) The flask was dried by flame, 290 mg of 1,3,5-tris(1H-tetrazole-5-yl) benzene hydrochloride (H3BTT·2HCl) and 3.5 ml of 0.31 mol / L chloroform were added to the flask, then 464 mg of m-chloroperbenzoic acid with a mass fraction of 75% was added dropwise to the flask to obtain a mixture, which is the first liquid.

[0031] (2) A polytetrafluoroethylene magnetic stirrer was placed in the flask, the flask was sealed, and the mixture was stirred in a preheated oil bath at 50°C for 19 hours. After the mixture was cooled to room temperature, it was diluted with 16.5 ml of 0.05 mol / L toluene. The flask was irradiated with a 390 nm LED lamp, and the stirring and irradiation were continued for 4 hours to obtain a mixture, which is the second liquid.

[0032] (3) The light was turned off, the flask was opened, and 0.81 ml of pyridine and 546 mg of ammonium carbonate were added to the second liquid to obtain a mixture, which is the third liquid. The flask was placed in an acetone bath and cooled to -78°C with liquid nitrogen, and then aerated with a 30% ozone-containing oxygen mixture for 10 minutes, followed by pure oxygen for 3 minutes, and finally nitrogen for 3 minutes. The flask was opened and the mixture was stirred at room temperature for 15 minutes to obtain a mixture, which is the fourth liquid.

[0033] (4) The flask was sealed and placed in a preheated oil bath and stirred at 90°C for 24 hours until the precipitate was completely filtered and then placed in an electrically heated constant temperature air drying oven at 80°C for 4 hours to obtain a first powder.

[0034] ​(5) Under argon atmosphere, 122 mg of the first powder and 380 mg of anhydrous ferrous chloride were added to a mixture of 40 mL of dimethylformamide and 40 mL of dimethyl sulfoxide, and reacted at a temperature of 110 °C for 24 hours. Filtration, washing with deionized water, and then drying in an electric thermostatic air-drying oven at 80 °C for 4 hours yielded a second powder.

[0035] (6) The second powder was loaded into a quartz tube, heated to 700 °C at a rate of 1 °C / min, and heat-treated under argon atmosphere at an argon flow rate of 20 mL / min for 90 minutes to yield a third powder.

[0036] (7) The third powder was added to a 1 mol / L sulfuric acid solution, ultrasonically treated for 2 hours, and then continuously stirred at 80 °C for 20 hours. Filtration, washing with deionized water, and then drying in an electric thermostatic air-drying oven at 80 °C for 4 hours yielded a fourth powder.

[0037] Example 2

[0038] A method for preparing a ZIF-derived non-noble metal electrocatalyst was prepared in this example, and the specific process was as follows:

[0039] (1) A flask was dried by flame, 250 mg of 1,3,5-tris(1H-tetrazole-5-yl) benzene hydrochloride and 3.5 ml of 0.31 mol / L chloroform were added to the flask, and then 400 mg of mass fraction 75% meta-chloroperoxybenzoic acid was added dropwise to the flask to obtain a mixture, i.e., a first liquid.

[0040] (2) A polytetrafluoroethylene magnetic stirrer was placed in the flask, the flask was sealed, and the mixture was stirred in a preheated oil bath at 40 °C for 20 hours. When the mixture cooled to room temperature, it was diluted with 16.5 ml of 0.05 mol / L toluene. The flask was irradiated with a 390 nm LED lamp, and the stirring and irradiation were continued for 3 hours to obtain a mixture, i.e., a second liquid.

[0041] (3) The light was turned off, the flask was opened, and 0.5 ml of pyridine and 500 mg of ammonium carbonate were added to the second liquid to obtain a mixture, i.e., a third liquid. The flask was placed in an ether bath, and the third liquid was cooled to -70 °C with liquid nitrogen and aerated with a 20% ozone-containing oxygen mixture for 15 minutes, then aerated with pure oxygen for 5 minutes, and finally aerated with nitrogen for 5 minutes. The flask was opened, and the mixture was stirred at room temperature for 15 minutes to obtain a mixture, i.e., a fourth liquid.

[0042] (4) The flask was sealed and placed in a preheated oil bath, and stirred at 85 °C for 24 hours until the precipitation was complete. Filtration, and then drying in an electric thermostatic air-drying oven at 80 °C for 4 hours yielded a first powder.

[0043] (5) Under argon atmosphere, 122 mg of the first powder and 366 mg of anhydrous ferrous chloride were added to a mixture of 40 mL of dimethylformamide and 40 mL of dimethyl sulfoxide, and reacted at a temperature of 100 °C for 24 hours. Filtration, washing with deionized water, and then drying in a thermostatically controlled forced air oven at 80 °C for 4 hours gave a second powder.

[0044] (6) The second powder was loaded into a quartz tube, heated to 800 °C at a rate of 1 °C / min under argon atmosphere, and heat treated under argon atmosphere at a flow rate of 20 mL / min for 90 minutes to give a third powder.

[0045] (7) The third powder was added to a 0.5 mol / L sulfuric acid solution, sonicated for 3 hours, and then continuously stirred at 80 °C for 20 hours. Filtration, washing with deionized water, and then drying in a thermostatically controlled forced air oven at 80 °C for 4 hours gave a fourth powder.

[0046] Example 3

[0047] A method for preparing a ZIF-derived non-noble metal electrocatalyst was prepared in this example. The specific process is as follows:

[0048] (1) A flask was dried by flame, 300 mg of 1,3,5-tris(1H-tetrazole-5-yl) benzene hydrochloride and 3.5 ml of 0.31 mol / L chloroform were added to the flask, then 440 mg of mass fraction 75% meta-chloroperoxybenzoic acid was added dropwise to the flask to obtain a mixture, which is the first liquid.

[0049] (2) A polytetrafluoroethylene magnetic stirrer was placed in the flask, the flask was sealed and placed in a preheated oil bath, and the mixture was stirred at 45 °C for 18 hours. When the mixture cooled to room temperature, it was diluted with 16.5 ml of 0.05 mol / L toluene. A 390 nm LED lamp was shone on the flask, and the stirring and irradiation were continuously carried out for 3.5 hours to obtain a mixture, which is the second liquid.

[0050] (3) The light was turned off, the flask was opened, 1 ml of pyridine and 560 mg of ammonium carbonate were added to the second liquid to obtain a mixture, which is the third liquid. The flask was placed in an ethyl acetate bath and the third liquid was cooled to -75 °C with liquid nitrogen and aerated with a mixture of 25% ozone in oxygen gas for 12 minutes, then aerated with pure oxygen for 4 minutes, and finally aerated with nitrogen for 4 minutes. The flask was opened and the mixture was stirred at room temperature for 15 minutes to obtain a mixture, which is the fourth liquid.

[0051] (4) The flask was sealed and placed in a preheated oil bath, and stirred at 87 °C for 24 hours until the precipitation was complete. Filtration, and then drying in a thermostatically controlled forced air oven at 80 °C for 4 hours gave a first powder.

[0052] (5) Under argon atmosphere, 122 mg of the first powder and 244 mg of anhydrous ferrous chloride were added to a mixture of 40 mL of dimethylformamide and 40 mL of dimethyl sulfoxide, and reacted at a temperature of 120 °C for 24 hours. Filtration, washing with deionized water, and then drying in an electric thermostatic air-drying oven at 80 °C for 4 hours yielded a second powder.

[0053] (6) The second powder was loaded into a quartz tube, heated to 900 °C at a rate of 1 °C / min, and heat-treated under argon atmosphere at an argon flow rate of 20 mL / min for 90 minutes to yield a third powder.

[0054] (7) The third powder was added to a 0.7 mol / L sulfuric acid solution, ultrasonically treated for 2.5 hours, and then continuously stirred at 80 °C for 20 hours. Filtration, washing with deionized water, and then drying in an electric thermostatic air-drying oven at 80 °C for 4 hours yielded a fourth powder.

[0055] Example 4

[0056] A method for preparing a ZIF-derived non-noble metal electrocatalyst was prepared in this example, and the specific process was as follows:

[0057] (1) A flask was dried by flame, 330 mg (1.0 mmol) of 1,3,5-tris(1H-tetrazole-5-yl) benzene hydrochloride and 3.5 ml of 0.31 mol / L chloroform were added to the flask, and then 480 mg of mass fraction 75% meta-chloroperoxybenzoic acid was added dropwise to the flask to obtain a mixture, i.e., a first liquid.

[0058] (2) A polytetrafluoroethylene magnetic stirrer was placed in the flask, the flask was sealed, and the mixture was stirred in a preheated oil bath at 55 °C for 17 hours. When the mixture cooled to room temperature, it was diluted with 16.5 ml of 0.05 mol / L toluene. The flask was irradiated with a 275 nm LED lamp, and the stirring and irradiation were continued for 4.5 hours to obtain a mixture, i.e., a second liquid.

[0059] (3) The light was turned off, the flask was opened, 1.5 ml of pyridine and 580 mg of ammonium carbonate were added to the second liquid to obtain a mixture, i.e., a third liquid. The flask was placed in an acetone bath, and the third liquid was cooled to -80 °C by adding dry ice and aerated with a mixture of 35% ozone in oxygen gas for 7 minutes, then aerated with pure oxygen for 2 minutes, and finally aerated with nitrogen for 2 minutes. The flask was opened, and the mixture was stirred at room temperature for 15 minutes to obtain a mixture, i.e., a fourth liquid.

[0060] (4) The flask was sealed and placed in a preheated oil bath, and stirred at 93 °C for 36 hours until the precipitate was completely filtered, and then dried in an electric thermostatic air-drying oven at 80 °C for 4 hours to obtain a first powder.

[0061] (5) Under argon atmosphere, 122 mg of the first powder and 427 mg of anhydrous ferrous chloride were added to a mixture of 40 mL of dimethylformamide and 40 mL of dimethyl sulfoxide, and reacted at a temperature of 140 °C for 36 hours. Filtration, washing with deionized water, and then drying in an electric thermostatic air-drying oven at 80 °C for 4 hours yielded a second powder.

[0062] (6) The second powder was loaded into a quartz tube, heated to 1000 °C at a rate of 1 °C / min, and heat-treated under argon atmosphere at an argon flow rate of 20 mL / min for 180 minutes to yield a third powder.

[0063] (7) The third powder was added to a 1.5 mol / L sulfuric acid solution, ultrasonically treated for 1.5 hours, and then continuously stirred at 80 °C for 20 hours. Filtration, washing with deionized water, and then drying in an electric thermostatic air-drying oven at 80 °C for 4 hours yielded a fourth powder.

[0064] Example 5

[0065] A method for preparing a ZIF-derived non-noble metal electrocatalyst was prepared in this example, and the specific process was as follows:

[0066] (1) A flask was dried by flame, 350 mg of 1,3,5-tris(1H-tetrazole-5-yl) benzene hydrochloride and 3.5 ml of 0.31 mol / L chloroform were added to the flask, and then 533 mg of mass fraction 75% meta-chloroperoxybenzoic acid was added dropwise to the flask to obtain a mixture, i.e., a first liquid.

[0067] (2) A polytetrafluoroethylene magnetic stirrer was placed in the flask, the flask was sealed, and the mixture was stirred in a preheated oil bath at 60 °C for 15 hours. When the mixture cooled to room temperature, it was diluted with 16.5 ml of 0.05 mol / L toluene. A 400 nm LED lamp was shone on the flask, and the stirring and irradiation were continuously performed for 5 hours to obtain a mixture, i.e., a second liquid.

[0068] (3) The light was turned off, the flask was opened, 2 ml of pyridine and 600 mg of ammonium carbonate were added to the second liquid to obtain a mixture, i.e., a third liquid. The flask was placed in an ether bath, and the third liquid was cooled to -77 °C by adding dry ice and aerated with a 40% ozone-containing oxygen mixture for 5 minutes, then aerated with pure oxygen for 1 minute, and finally aerated with nitrogen for 1 minute. The flask was opened, and the mixture was stirred at room temperature for 15 minutes to obtain a mixture, i.e., a fourth liquid.

[0069] (4) The flask was sealed and placed in a preheated oil bath, and stirred at 95 °C for 12 hours until the precipitation was complete. Filtration, and then drying in an electric thermostatic air-drying oven at 80 °C for 4 hours yielded a first powder.

[0070] (5) Under argon atmosphere, 122 mg of the first powder and 488 mg of anhydrous ferrous chloride were added to a mixture of 40 mL of dimethylformamide and 40 mL of dimethyl sulfoxide, and reacted at a temperature of 150°C for 12 hours. After filtration and washing with deionized water, the product was dried in an electric thermostatic air-drying oven at 80°C for 4 hours to obtain a second powder.

[0071] (6) The second powder was loaded into a quartz tube, heated to 1000°C at a rate of 1°C / min, and heat-treated under argon atmosphere at an argon flow rate of 20 mL / min for 60 minutes to obtain a third powder.

[0072] (7) The third powder was added to a 2 mol / L sulfuric acid solution, ultrasonically treated for 1 hour, and then continuously stirred at 80°C for 20 hours. After filtration and washing with deionized water, the product was dried in an electric thermostatic air-drying oven at 80°C for 4 hours to obtain a fourth powder.

[0073] Working principle:

[0074] By converting carbon atoms to nitrogen atoms in H3BTT·2HCl, the first oxidative restructuring of the benzene ring produces an open-ring intermediate with an electron affinity site, preparing for ring closure and carbon-based leaving groups, in situ generating an intermediate with two carbonyl groups, activated to form a carboxylate leaving group, while simultaneously facilitating the condensation of ammonia and ultimately the product, converting the benzene ring with different positions and different groups to the corresponding pyridine derivative in one step, replacing carbon atoms with nitrogen atoms, which can control the amount of nitrogen doping and effectively increase the content of nitrogen elements. Nitrogen atoms are part of the active site and play a key role in catalyst activity. By this method, various types of nitrogen atoms are added, including nitrogen atoms located at the edge of the carbon plane, each of which is connected to two carbon atoms and donates a p electron to the aromatic p system, and nitrogen atom types connected to three carbon atoms, thereby increasing efficient electrocatalytic activity. Further synthesis of porous metal-organic framework materials, in which metal ions or metal clusters are connected together by organic linkers, with truncated octahedra as the main building unit, adjacent octahedra share square faces in space to form a cubic framework. Centered on a chloride, it binds to nitrogen atoms from four different ligands. The homogeneous phase of the polyhedral-shaped particle is similar to the ZIF-8 crystal, but the surface and edges are more rough. Due to its three-dimensional crystalline structure, it can provide a high density of active sites uniformly distributed in the framework. Further conversion of organic ligands to carbon supports by thermal decomposition, so that active metal-containing materials and carbon supports can be formed simultaneously. The porosity of the carbon produced by thermal cracking can ensure the accessibility of the active sites to the reactants and products related to ORR. First, it is thermally decomposed under a protective gas stream to form iron / nitrogen / carbon active sites. During thermal decomposition, the synthesized organic part will be carbonized to form carbon, thereby providing the required electronic conductivity. And by pyrolysis, the degree of graphitization is increased, thereby increasing the active site density. The ordered lattice of graphitized carbon can promote the formation of active sites generated by nitrogen doping, and also increase the electronic conductivity of the catalyst. At the same time, during the heat treatment, the microporous structure is further developed. Then, during the chemical pickling process, most of the iron is dissolved. It can avoid the pollution of the proton exchange membrane caused by unstable iron-containing species in the acidic environment, thereby increasing the service life of the fuel cell.

[0075] The preparation method of the ZIF-derived non-noble metal electrocatalyst was tested, and the results are shown in Figures 2 to 3

[0076] The test was carried out on a rotating disc electrode and an electrochemical workstation, the working electrode was a glassy carbon electrode, the reference electrode was a Hg / HgSO4 electrode, and the counter electrode was a platinum wire. The electrolyte solution was 0.1M perchloric acid (saturated with oxygen), and the test method was linear sweep voltammetry, and the test process was completed at room temperature and pressure.

[0077] ​As shown in Figure 3 The electrode made of the ZIF-derived non-noble metal electrocatalyst of Example 1 has a starting potential of 0.96 V (vs. RHE) and a half-wave potential of 0.82 V (vs. RHE) under acidic conditions, and has a mass activity of 4.74 A / g (@ 0.8 V vs. RHE), reaching the average activity level of the non-noble metal catalysts for fuel cells reported so far under acidic test conditions.

[0078] The embodiments of the present application are described in detail above with reference to the drawings, but the present application is not limited to the above-described embodiments, and various changes can be made within the scope of knowledge of those skilled in the art without departing from the purpose of the present application. In addition, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0079] It should also be noted that the terms "comprising", "containing" or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles or devices that include a series of elements not only include those elements, but also include other elements not explicitly listed or inherent to such processes, methods, articles or devices. Without more limitations, the element defined by the phrase "comprising a" does not exclude the presence of additional identical elements in the process, method, article or device that includes the element.

[0080] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can modify the technical solutions recorded in the foregoing embodiments or make equivalent replacements to some technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for the preparation of ZIF-derived non-noble metal electrocatalysts, characterized in that, Comprising: S1: adding H3BTT·2HC1 and chloroform into a container under a protective atmosphere, dropping meta-chloroperoxybenzoic acid into the container to obtain a first liquid; S2: sealing the container, incubating the first liquid at 40-60°C for 15-20 hours, adding toluene after natural cooling, stirring the first liquid, and irradiating 275-400 nm ultraviolet light for 3-5 hours to obtain a second liquid; S3: opening the container, adding pyridine and ammonium carbonate, and stirring to obtain a third liquid; S4: incubating the third liquid at -70- -80°C, bubbling ozone and oxygen mixed gas into the third liquid for 5-15 minutes, bubbling pure oxygen into the third liquid for 1-5 minutes, and bubbling nitrogen into the third liquid for 1-5 minutes to obtain a fourth liquid; S5: incubating the fourth liquid at 85-95°C for 12-36 hours, and filtering and drying to obtain a first powder; S6: adding the first powder and anhydrous ferrous chloride into a mixed solution of dimethylformamide and dimethyl sulfoxide under a protective atmosphere, incubating at 100-150°C for 12-36 hours, filtering, and drying to obtain a second powder; S7: incubating the second powder at 700-1000°C for 60-180 minutes under a protective atmosphere to obtain the ZIF-derived non-noble metal electrocatalyst; The mass ratio of the H3BTT·2HC1, the meta-chloroperoxybenzoic acid, the pyridine, and the ammonium carbonate is 250-350:300-400:0.5-2:500-600.

2. The method for preparing the ZIF-derived non-noble metal electrocatalyst according to claim 1, characterized in that, The S7: incubating the second powder at 700-1000°C for 90 minutes under a protective atmosphere to obtain a third powder; further comprising: S8: adding the third powder into a sulfuric acid solution, ultrasonicating for 1-3 hours, filtering, washing, and drying to obtain the ZIF-derived non-noble metal electrocatalyst.

3. The method for preparing the ZIF-derived non-noble metal electrocatalyst according to claim 2, characterized in that, The concentration of the sulfuric acid solution is 0.5-2 mol / L.

4. The method for preparing the ZIF-derived non-noble metal electrocatalyst according to claim 1, characterized in that, The mass ratio of the first powder and the anhydrous ferrous chloride is 1:3-4.

5. The method for preparing the ZIF-derived non-noble metal electrocatalyst according to claim 1, characterized in that, The concentration of ozone in the ozone and oxygen mixed gas is 20%-40%.

6. The method for preparing the ZIF-derived non-noble metal electrocatalyst according to claim 1, characterized in that, The S4: placing the container in an acetone, diethyl ether, or ethyl acetate bath, and adding dry ice or liquid nitrogen to incubate the third liquid at -70- -80°C, bubbling ozone and oxygen mixed gas into the third liquid for 5-15 minutes, bubbling pure oxygen into the third liquid for 1-5 minutes, and bubbling nitrogen into the third liquid for 1-5 minutes to obtain the fourth liquid.

7. The method for preparing the ZIF-derived non-noble metal electrocatalyst according to claim 1, characterized in that, The S4: incubating the third liquid at -78°C, bubbling ozone and oxygen mixed gas into the third liquid for 10 minutes, bubbling pure oxygen into the third liquid for 3 minutes, and bubbling nitrogen into the third liquid for 3 minutes to obtain the fourth liquid.

8. The method of claim 1 to 7, wherein the ZIF derived non-noble metal electrocatalyst is prepared by, In the S2, the wavelength of the ultraviolet light is 390 nm.

9. The ZIF-derived non-noble metal electrocatalyst prepared by the preparation method according to any one of claims 1-8.

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