Preparation method and application of carbon-based oxygen reduction catalyst

Abstract

The present application relates to the technical field of electrocatalytic materials, and particularly relates to a preparation method of a carbon-based oxygen reduction catalyst and application thereof, and the preparation method of the carbon-based oxygen reduction catalyst provided by the present application mainly comprises the following steps: S1: attaching acetylacetone metal on the surface of a carbon-based carrier by a gas-phase impregnation method to obtain carbon-based material attached with acetylacetone metal; S2: using ammonia water to replace the ligand of the carbon-based material attached with acetylacetone metal by a liquid-phase replacement method, and then drying to obtain carbon-based material attached with an amino metal complex compound; S3: obtaining the carbon-based oxygen reduction catalyst by high-temperature calcination of the carbon-based material attached with the amino complex compound. The preparation method has the advantages of simple process, lower preparation cost, and better catalytic activity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrocatalytic materials, and in particular to a preparation method of a carbon-based oxygen reduction catalyst and application thereof. BACKGROUND

[0002] In order to alleviate the pressure of people's demand for traditional energy, it is urgent to develop renewable and sustainable energy to replace traditional energy. Among many technologies, fuel cell technology has extremely high reliability and can efficiently convert chemical energy into electrical energy through electrochemical means, thereby providing clean, pollution-free and sustainable energy. According to the difference of electrolyte, fuel cells can be divided into the following categories: proton exchange membrane fuel cell, solid oxide fuel cell, phosphoric acid fuel cell, methanol fuel cell and molten carbonate fuel cell.

[0003] As a representative of fuel cells, the proton exchange membrane fuel cell has been a research hotspot compared with other batteries due to its low working temperature, high energy density, low mass and small volume. However, due to the very slow kinetics of the cathode, it has a high potential, so a catalyst is needed to assist the reaction. The commonly used catalysts mainly include two categories, including noble metal catalysts and non-noble metal catalysts, among which commercial Pt / C belongs to noble metal catalysts and is one of the catalysts with the best catalytic performance at present. However, due to the small storage of Pt and high price, it hinders the commercialization of fuel cells.

[0004] In order to overcome the price defects of the catalyst, people actively develop non-noble metal catalysts. In recent years, people have researched and developed transition metal supported on carbon materials, which has become one of the most potential materials to replace noble metal catalysts. However, the transition metal-carbon material in the prior art has low catalytic activity for oxygen reduction reaction and cannot reach the level of noble metal catalysts. Moreover, the preparation process is complex and cannot form a scale effect. For example, the Chinese invention patent with the document number CN113013428A discloses a preparation method and application of Fe, Co double metal doped mesoporous carbon oxygen reduction catalyst. However, the preparation method adopted by the patent has a complex preparation process for the prepared Fe, Co double metal doped mesoporous carbon oxygen reduction catalyst, and the catalytic performance is still inferior to the existing commercial Pt / C, which still needs to be further improved. SUMMARY

[0005] In order to solve the above technical problems, the purpose of the present application is to provide a preparation method of a carbon-based oxygen reduction catalyst and application thereof. The preparation method of the oxygen reduction catalyst has a simple preparation process, lower preparation cost and better catalytic activity.

[0006] In order to achieve the above technical effects, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a carbon-based oxygen reduction catalyst, which is prepared by using a carbon-based carrier as a carbon precursor, acetylacetone metal as a non-noble metal precursor, and ammonia as a ligand replacement agent.

[0008] Preferably, the acetylacetone iron and the acetylacetone cobalt are attached to the surface of the carbon-based carrier by a gas-phase impregnation method to obtain a carbon-based material attached with acetylacetone cobalt and acetylacetone iron, and the ammonia is used to further replace the ligand of the carbon-based material attached with acetylacetone cobalt and acetylacetone iron by a liquid-phase replacement method to obtain a carbon-based material attached with amino cobalt / iron coordination compounds, and finally, the carbon-based material attached with amino cobalt / iron coordination compounds is calcined at a high temperature to obtain the Fe-Co-N co-doped carbon-based oxygen reduction catalyst.

[0009] In a second aspect, the present application provides a preparation method of a carbon-based oxygen reduction catalyst, which comprises the following steps:

[0010] S1: attaching acetylacetone metal to the surface of a carbon-based carrier by a gas-phase impregnation method to obtain a carbon-based material attached with acetylacetone metal;

[0011] S2: replacing the ligand of the carbon-based material attached with acetylacetone metal by using ammonia through a liquid-phase replacement method, and then drying to obtain a carbon-based material attached with amino metal coordination compounds;

[0012] S3: calcining the carbon-based material attached with amino coordination compounds at a high temperature to obtain a carbon-based oxygen reduction catalyst.

[0013] Further, the conditions of the gas-phase impregnation method are high temperature and high pressure.

[0014] Further, the conditions of the high temperature and high pressure are specifically a temperature of 150-250°C, a pressure of 0-3 MPa, and a treatment time of 1-12 h.

[0015] Preferably, the conditions of the high temperature and high pressure are specifically a temperature of 180-240°C, a pressure of 1-3 MPa, and a treatment time of 1.5-6 h.

[0016] Further, the acetylacetone metal in S1 is any one or a combination of acetylacetone iron, acetylacetone cobalt, and acetylacetone nickel, and is preferably a mixture of acetylacetone iron and acetylacetone cobalt.

[0017] Further, the carbon-based carrier in S1 is any one of organic carbon or inorganic carbon.

[0018] Further, the carbon-based carrier can be at least one of carbon black, carbon nanotube, graphene, two-dimensional carbon sheet and graphene oxide, or at least one of carbon black, carbon nanotube, graphene, two-dimensional carbon sheet and graphene oxide modified by a nitrogen-containing polymer.

[0019] Further, the ammonia water concentration in S2 is 25-28%, the replacement time is 0.5-10h, and the drying temperature is 60-100℃, and the drying time is 1-24h.

[0020] Further, the high-temperature calcination temperature in S3 is 300-1100℃, and the high-temperature calcination time is 0.2-3h.

[0021] Further, S3 further comprises: after high-temperature calcination, removing larger metal particles in the carbonized product by washing with acid solution, and then washing several times with ultrapure water and drying, to obtain the carbon-based oxygen reduction catalyst.

[0022] Further, the acid solution is any one of sulfuric acid solution or hydrochloric acid solution.

[0023] Further, the high-temperature calcination environment is an inert gas environment, and the inert gas environment is preferably any one of nitrogen or argon.

[0024] In a third aspect, the application further provides an application of the carbon-based oxygen reduction catalyst of the first aspect, or the carbon-based oxygen reduction catalyst prepared by the preparation method of the second aspect, specifically including an application in a proton exchange membrane fuel cell, or an application as an oxygen reduction catalyst material for a fuel cell or a metal-air battery.

[0025] Compared with the prior art, the application has the following beneficial effects:

[0026] In a first aspect, the application provides a carbon-based oxygen reduction catalyst, which uses a carbon-based carrier as a carbon precursor, iron acetylacetonate as an iron precursor, cobalt acetylacetonate as a cobalt precursor, and ammonia water as a nitrogen precursor. In the preparation of the carbon-based oxygen reduction catalyst, first, the iron acetylacetonate and the cobalt acetylacetonate are attached to the surface of the carbon-based carrier by a gas-phase impregnation method, to obtain a carbon-based material attached with the cobalt acetylacetonate and the iron acetylacetonate. Then, the ammonia water is used to further replace the ligand of the carbon-based material attached with the cobalt acetylacetonate and the iron acetylacetonate by a liquid-phase replacement method, to obtain a carbon-based material attached with cobalt / iron amino ligand compounds. Finally, the carbon-based material attached with the cobalt / iron amino ligand compounds is subjected to high-temperature calcination, to obtain the carbon-based oxygen reduction catalyst. This carbon-based oxygen reduction catalyst preparation method is simple, and the active metals are uniformly attached to the surface of the carrier. The prepared carbon-based oxygen reduction catalyst has a performance comparable to that of a commercial Pt / C.

[0027] In a second aspect, the present application also provides a preparation method of the carbon-based oxygen reduction catalyst, which abandons the traditional hydrothermal method and adopts a gas-phase impregnation method, so that the catalytically active metal can be quickly and conveniently loaded on the surface of the carbon-based carrier, uniformly distributed on the surface of the carrier with the minimum amount, effectively improving the utilization rate of raw materials, and a liquid-phase replacement method is used after the gas-phase impregnation method to obtain a metal complex with higher stability, and a calcination process is used to form a catalytically active site, thereby improving the stability of the catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 SEM of the carbon nanotubes provided for the first embodiment of the present application;

[0029] Figure 2 X-ray photoelectron spectrogram of the N element provided for the second embodiment of the present application;

[0030] Figure 3 Comparison results of oxygen reduction performance of the carbon-based oxygen reduction catalyst prepared in Example 1 to Example 3 in the test example provided for the third embodiment of the present application in a 0.1 mol / L KOH solution. DETAILED DESCRIPTION

[0031] The embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, but cannot limit the protection scope of the present application. The embodiments are only used to explain the present application, and are not used to limit the scope of the present application. The test methods used in the following embodiments are conventional methods unless otherwise specified; the materials, reagents or instruments used are not marked with the manufacturer unless otherwise specified, which are reagents and materials that can be obtained from commercial channels, and the specific conditions are not marked in the embodiments, which are carried out according to the conventional conditions or the conditions recommended by the manufacturer.

[0032] Example 1

[0033] Please refer to Figure 1 , Figure 1 SEM of the carbon nanotubes used in the present embodiment;

[0034] The present embodiment is the first embodiment of the present application, and the present embodiment provides a carbon-based oxygen reduction catalyst, which is prepared by the following method:

[0035] S1: 0.5 g of carbon nanotubes and 1 g of iron acetylacetonate are weighed and placed in a high-pressure hydrothermal reactor, and then impregnated for 1.5 h at 180℃ under a pressure of 1 MPa by using a high-temperature and high-pressure gas-phase impregnation method, to obtain carbon-based materials attached with iron acetylacetonate;

[0036] S2: The carbon-based material with attached acetylacetone iron is soaked in an ammonia solution with a concentration of 25% for 6 hours, and then dried at a temperature of 70°C for 12 hours to obtain a carbon-based material with attached amino iron coordination compounds;

[0037] S3: After drying the carbon-based carrier with attached amino iron coordination compounds, the carrier is transferred into a porcelain boat and placed in a tube furnace for high-temperature carbonization under an argon atmosphere at 700°C for 0.5 hours. After naturally cooling to room temperature, the carbonization product is treated with 1 mol / L hydrochloric acid to remove larger metal particles, washed with pure water several times, and dried to obtain a Fe, N-doped carbon-based material catalyst (labeled as Fe-N-C).

[0038] Example 2

[0039] See Figure 2 This example is a second example of the present application, and provides a carbon-based oxygen reduction catalyst prepared by the following method:

[0040] S1: 1 g of carbon nanotubes and 1.5 g of acetylacetone nickel are weighed and placed in a high-pressure hydrothermal reactor, and then subjected to high-temperature and high-pressure gas-phase impregnation at a temperature of 240°C and a pressure of 3 MPa for 4 hours to obtain a carbon-based material with attached acetylacetone nickel;

[0041] S2: The carbon-based material with attached acetylacetone nickel is soaked in an ammonia solution with a concentration of 25% for 8 hours, and then dried at a temperature of 90°C for 10 hours to obtain a carbon-based material with attached amino nickel coordination compounds;

[0042] S3: After drying, the sample is transferred into a porcelain boat and placed in a tube furnace for high-temperature carbonization under an argon atmosphere at 900°C for 60 minutes. After naturally cooling to room temperature, the carbonization product is treated with hydrochloric acid to remove larger metal particles, washed with pure water several times, and dried to obtain a Ni, N-doped carbon-based material catalyst (labeled as Ni-N-C).

[0043] In this example, the N element in the prepared Ni, N-doped carbon-based material catalyst is subjected to X-ray photoelectron spectroscopy, and the experimental results are shown in Figure 2 .

[0044] Example 3

[0045] This example is a third example of the present application, and provides a carbon-based oxygen reduction catalyst prepared by the following method:

[0046] S1: using high temperature and high pressure gas phase impregnation method, 1g of commercial carbon black, 1g of cobalt acetylacetone and 1g of iron acetylacetone are weighed and placed in a sealed container, the temperature is set to 185℃, the pressure is set to 2MPa, and the impregnation is carried out for 6h, to obtain carbon-based material attached with cobalt acetylacetone and iron acetylacetone;

[0047] S2: the carbon-based material attached with cobalt acetylacetone and iron acetylacetone is soaked in an ammonia solution with a concentration of 28% for 10h, and then dried at a temperature of 100℃ for 20h, to obtain carbon-based material attached with amino cobalt / iron coordination compounds.

[0048] S3: the carbon-based material attached with amino cobalt / iron coordination compounds is dried, and the dried carbon-based material attached with amino cobalt / iron coordination compounds is transferred to a ceramic boat and placed in a tube furnace, and carbonized at a temperature of 1000℃ in an argon atmosphere for 60min. After naturally cooling to room temperature, larger metal particles are removed with sulfuric acid, and the material is washed several times with ultrapure water and dried, to obtain a Co, Fe, N-doped carbon-based material catalyst (labeled as Co / Fe-N-C).

[0049] Test example

[0050] The carbon-based oxygen reduction catalysts prepared in Examples 1-3 are subjected to three-electrode system oxygen reduction performance test, and the electrochemical performance is tested in 0.1mol / l KOH solution, and the test results are shown in Table 1. Figure 3

[0051] The above test results show that the catalytic performance of Co / Fe-N-C is the best, and is equivalent to that of commercial Pt / C, followed by Ni-N-C, and then Fe-N-C.

[0052] The above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the purpose and scope of the present application, and they should be covered in the scope of the claims of the present application. The technical, shape and structure parts not described in detail in the present application are well-known technologies.​

Claims

1. A method for preparing a carbon-based oxygen reduction catalyst, characterized by, consists of the following steps: S1: attaching acetylacetone metal of any one or more combinations of acetylacetone iron, acetylacetone cobalt and acetylacetone nickel on the surface of a carbon-based carrier by a gas-phase impregnation method, wherein the high-temperature and high-pressure conditions are specifically a temperature of 180-240℃, a pressure of 1-3 MPa, and a treatment time of 1.5-6 h, to obtain a carbon-based material with acetylacetone metal attached thereon; S2: using ammonia water to displace the ligand of the carbon-based material with acetylacetone metal of any one or more combinations of acetylacetone iron, acetylacetone cobalt and acetylacetone nickel attached thereon by a liquid-phase displacement method, with a displacement time of 0.5-10 h, followed by drying, to obtain a carbon-based material with amino metal coordination compounds attached thereon; S3: obtaining a carbon-based oxygen reduction catalyst by high-temperature calcination of the carbon-based material with amino coordination compounds attached thereon, followed by removal of larger metal particles in the carbonization product by washing with an acid solution, and then washing with ultrapure water for several times and drying.

2. The method for preparing a carbon-based oxygen reduction catalyst according to claim 1, wherein: The carbon-based carrier in S1 is any one of organic carbon or inorganic carbon.

3. The method of making a carbon-based oxygen reduction catalyst according to claim 1, wherein: The drying temperature in S2 is 60-100℃, and the drying time is 1-24 h.

4. Use of a carbon-based oxygen reduction catalyst prepared by the preparation method of the oxygen reduction catalyst according to any one of claims 1-3 in a proton exchange membrane fuel cell.

5. Use of a carbon-based oxygen reduction catalyst prepared by the preparation method of the oxygen reduction catalyst according to any one of claims 1-3 as an oxygen reduction catalyst material for fuel cells or metal-air batteries.

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