Preparation method and application of a heteroatom-doped porous carbon material

Abstract

The present application relates to a preparation method of a heteroatom doped porous carbon material, and belongs to the technical field of material preparation. The preparation method of the heteroatom doped porous carbon material comprises the following steps: first, modifying a nitrogen source and a phosphorus source on the surface of a template agent in sequence, and then using heavy oil with an asphaltene content of not less than 40wt% as a carbon source to prepare a nitrogen-phosphorus co-doped porous carbon material through in-situ modification by a template method. The present application also provides an application of the above-mentioned heteroatom doped porous carbon material as a catalyst in electrocatalytic oxygen reduction. Compared with traditional post-doped nitrogen-phosphorus co-doped porous carbon materials, the method can realize uniform and synergistic doping of nitrogen and phosphorus, the preparation process is simple, the product has excellent electrocatalytic oxygen reduction reaction performance, and the heavy oil with a high asphaltene content such as hard pitch is used as a raw material, so the cost is low, and the method has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of material preparation, and particularly relates to a preparation method and application of a heteroatom-doped porous carbon material. BACKGROUND

[0002] With the increasingly prominent energy and environmental problems, fuel cells, as a kind of high-efficiency and clean energy conversion device, have a wide application prospect. However, due to the low kinetic reaction rate of the cathode oxygen reduction reaction (ORR), a noble metal catalyst with high catalytic activity and reaction stability is required, and the commonly used one is a platinum-based (Pt / C) catalyst.

[0003] However, the Pt / C catalyst mainly has the following shortcomings: (1) the price of platinum is high and the reserves are limited. The cost of the catalyst can account for half of the fuel cell device. (2) The stability of platinum is poor. In the reaction process, platinum has problems such as sintering, dissolution, and agglomeration, which greatly reduces the performance of the fuel cell. (3) Platinum is easy to be poisoned. Platinum is easy to be affected by carbon monoxide generated by fuels such as methanol, which poisons the active sites of platinum, causes mixed potential to be generated, and thus reduces the output power of the fuel cell. These shortcomings greatly hinder the wide promotion of fuel cells. Therefore, designing a catalyst with stable properties and activity comparable to or even exceeding platinum is the most important task in the development process of fuel cells.

[0004] Heteroatom-doped carbon catalysts are considered to be a new generation of fuel cell catalysts that can replace platinum-based catalysts because of their high ORR catalytic activity, good methanol tolerance, low cost, long service life, and environmental friendliness. At present, the research mainly focuses on nitrogen, phosphorus, sulfur, and boron-doped carbon materials as oxygen reduction reaction catalysts. At present, the heteroatom-doped carbon catalysts have problems such as high preparation cost, long process flow, uneven distribution of doped sites, and large gap between performance and platinum-based catalysts. SUMMARY

[0005] In view of the deficiencies in the prior art, the present application aims to overcome the problems of the prior art, such as complex preparation process of nitrogen and phosphorus co-doped carbon materials, low nitrogen and phosphorus doping amount, and uneven distribution of doped sites, and provides a preparation method and application of a heteroatom-doped porous carbon material with simple preparation process, uniform distribution of nitrogen and phosphorus doping, and excellent catalytic performance.

[0006] To this end, the present application provides a preparation method of a heteroatom-doped porous carbon material, which comprises the following steps: first, modifying a nitrogen source and a phosphorus source on the surface of a template agent in sequence, and then using heavy oil with a pitch content of not less than 40wt% as a carbon source to prepare a nitrogen and phosphorus co-doped porous carbon material by in-situ modification through a template method.

[0007] The preparation method of the heteroatom-doped porous carbon material, wherein preferably, the template agent is a nano metal oxide, and further preferably, the metal oxide is iron oxide. The nano iron oxide has a catalytic graphitization effect.

[0008] The preparation method of the heteroatom-doped porous carbon material, wherein preferably, the nitrogen source is an amine group-containing polymer molecule.

[0009] The preparation method of the heteroatom-doped porous carbon material, wherein preferably, the nitrogen source is selected from at least one of polyaniline, chitosan, polyethyleneimine, and polyacrylamide, and further preferably, the nitrogen source is polyethyleneimine.

[0010] The preparation method of the heteroatom-doped porous carbon material, wherein preferably, the phosphorus source is a phosphoric acid group-containing molecule, and further preferably, the phosphorus source is selected from at least one of phytic acid, phosphoric acid, and metaphosphoric acid, and further preferably, the phosphorus source is phytic acid.

[0011] The preparation method of the heteroatom-doped porous carbon material, wherein preferably, the carbon source is selected from at least one of deoiled pitch and vacuum residue, and further preferably, the carbon source is deoiled pitch.

[0012] The preparation method of the heteroatom-doped porous carbon material, wherein preferably, the step of sequentially modifying the nitrogen source and the phosphorus source on the surface of the template agent comprises the following steps:

[0013] (1) uniformly mixing the template agent and the nitrogen source in water to coat the nitrogen source on the surface of the template agent; then adding the phosphorus source and further uniformly mixing to obtain the template agent modified by the nitrogen source and the phosphorus source on the surface.

[0014] The preparation method of the heteroatom-doped porous carbon material, wherein preferably, the step of in-situ modifying the nitrogen-phosphorus co-doped porous carbon material by the template method comprises the following steps:

[0015] (2) adding a solvent to the carbon source and uniformly ultrasonically dispersing; then adding the template agent modified by the nitrogen source and the phosphorus source in step (1), evaporating the solvent in the obtained mixed solution, and taking out the solid mixture;

[0016] (3) heating the solid mixture obtained in step (2) in a tube furnace under a nitrogen atmosphere at a temperature increasing rate of 5-10 ℃ / min -1 , maintaining the temperature at 700-1000 ℃ for 3 h, and high-temperature calcining;

[0017] (4) acid washing the mixture after the calcining in step (3) to remove the template agent, washing with water until neutral, and drying to obtain the nitrogen-phosphorus co-doped porous carbon material.

[0018] The preparation method of the heteroatom-doped porous carbon material, wherein preferably, the nitrogen content of the nitrogen-phosphorus co-doped porous carbon material is 2-5%, the phosphorus content is 1-2%, the specific surface area is 500-800 m 2 g -1 .

[0019] To this end, the application further provides a use of the above-mentioned heteroatom-doped porous carbon material as a catalyst in electrocatalytic oxygen reduction, in particular, a catalyst for cathode electrocatalytic oxygen reduction reaction of a fuel cell.

[0020] The preparation method of the heteroatom-doped porous carbon material of the application has the following specific technical solutions:

[0021] (1) mixing a template agent and a nitrogen source, adding deionized water, and ultrasonic dispersion to make the nitrogen source coat the surface of the template agent; then adding a phosphorus source, stirring and reacting, and after filtration and drying, obtaining a template agent coated with a nitrogen source and a phosphorus source on the surface;

[0022] (2) adding toluene solvent to the carbon source and ultrasonic dispersion to make it uniform; then adding the template agent coated with a nitrogen source and a phosphorus source in step (1), evaporating the solvent in the mixed solution at 60 DEG C, and taking out the solid mixture;

[0023] (3) calcining the solid mixture in step (2) in a tube furnace under a nitrogen atmosphere;

[0024] (4) acid washing the mixture after calcination in step (3) to remove the template agent, washing with water to neutral, and drying to obtain a nitrogen-phosphorus co-doped porous carbon material.

[0025] The technical solutions of the application have the following advantages:

[0026] The preparation method of the application develops a new method for preparing a nitrogen-phosphorus co-doped porous carbon material by using heavy oil as a carbon source. The method improves the traditional hard template method, coats and modifies the surface of a nano-oxide template agent with a nitrogen source, and then modifies a phosphorus source through electrostatic interaction between the nitrogen source and the phosphorus source, to realize in-situ doping of nitrogen and phosphorus in the subsequent heat treatment process.

[0027] The preparation method of the application can make the nitrogen and phosphorus source uniformly dispersed through pre-coating and modification, so that the nitrogen and phosphorus in the prepared carbon material can uniformly dope the carbon material.

[0028] In addition, the application selects nano Fe2O3 as a template agent, which has a certain catalytic graphitization effect in the heat treatment process, and can make nitrogen and phosphorus elements better embedded in the crystal lattice of the porous carbon material. Compared with the traditional post-doped nitrogen and phosphorus co-doped porous carbon material, the method can realize in-situ uniform doping of nitrogen and phosphorus, has a simple preparation process, has higher catalytic efficiency for electrocatalytic oxygen reduction, and uses heavy oil with high asphalt content such as deoiled asphalt and vacuum residue as raw material, so that the cost is low, and the method has a wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1a A TEM diagram of the nitrogen and phosphorus co-doped porous carbon material prepared in Example 1 of the application;

[0030] Figure 1b An electrocatalytic oxygen reduction performance diagram of the nitrogen and phosphorus co-doped porous carbon material prepared in Example 1 of the application;

[0031] Figure 2a A TEM diagram of the nitrogen and phosphorus co-doped porous carbon material prepared in Example 2 of the application;

[0032] Figure 2b An electrocatalytic oxygen reduction performance diagram of the nitrogen and phosphorus co-doped porous carbon material prepared in Example 2 of the application;

[0033] Figure 2c A nitrogen element distribution diagram of the nitrogen and phosphorus co-doped porous carbon material prepared in Example 2;

[0034] Figure 2d A phosphorus element distribution diagram of the nitrogen and phosphorus co-doped porous carbon material prepared in Example 2;

[0035] Figure 2e A carbon element distribution diagram of the nitrogen and phosphorus co-doped porous carbon material prepared in Example 2;

[0036] Figure 3a A TEM diagram of the nitrogen and phosphorus co-doped porous carbon material prepared in Example 3 of the application;

[0037] Figure 3b An electrocatalytic oxygen reduction performance diagram of the nitrogen and phosphorus co-doped porous carbon material prepared in Example 3 of the application;

[0038] Figure 4a A TEM of the nitrogen and phosphorus co-doped porous carbon material prepared in Example 4 of the application;

[0039] Figure 4b An electrocatalytic oxygen reduction performance diagram of the nitrogen and phosphorus co-doped porous carbon material prepared in Example 4 of the application;

[0040] Figure 5aTEM of the nitrogen and phosphorus co-doped porous carbon material prepared in Example 5 of the present application;

[0041] Figure 5b Electrocatalytic oxygen reduction performance chart of the nitrogen and phosphorus co-doped porous carbon material prepared in Example 5 of the present application;

[0042] Figure 6a TEM of the nitrogen and phosphorus co-doped porous carbon material prepared in Example 6 of the present application;

[0043] Figure 6b Electrocatalytic oxygen reduction performance chart of the nitrogen and phosphorus co-doped porous carbon material prepared in Example 6 of the present application;

[0044] Figure 7a TEM of the nitrogen and phosphorus co-doped porous carbon material prepared in Example 7 of the present application;

[0045] Figure 7b Electrocatalytic oxygen reduction performance chart of the nitrogen and phosphorus co-doped porous carbon material prepared in Example 7 of the present application;

[0046] Figure 8a TEM of the nitrogen and phosphorus co-doped porous carbon material prepared in Comparative Example 1 of the present application;

[0047] Figure 8b Electrocatalytic oxygen reduction performance chart of the nitrogen and phosphorus co-doped porous carbon material prepared in Comparative Example 1 of the present application;

[0048] Figure 9a TEM of the nitrogen and phosphorus co-doped porous carbon material prepared in Comparative Example 2 of the present application;

[0049] Figure 9b Electrocatalytic oxygen reduction performance chart of the nitrogen and phosphorus co-doped porous carbon material prepared in Comparative Example 2 of the present application;

[0050] Figure 10a TEM of the nitrogen and phosphorus co-doped porous carbon material prepared in Comparative Example 3 of the present application;

[0051] Figure 10b Electrocatalytic oxygen reduction performance chart of the nitrogen and phosphorus co-doped porous carbon material prepared in Comparative Example 3 of the present application;

[0052] Figure 11 Electrocatalytic oxygen reduction stability test schematic diagram of the nitrogen and phosphorus co-doped porous carbon prepared in Example 2 and Comparative Examples 1-3 of the present application; the curves from top to bottom in the diagram are: Example 2, Pt / C, Comparative Example 1, Comparative Example 2, Comparative Example 3. DETAILED DESCRIPTION

[0053] The following detailed description of the embodiments of the present application is based on the premise of the technical solutions of the present application, and detailed implementation manners and processes are given, but the protection scope of the present application is not limited to the following embodiments. The experimental methods not specified in the following embodiments are usually carried out under conventional conditions.

[0054] Example 1

[0055] The preparation method of the nitrogen and phosphorus co-doped porous carbon material in this example is as follows:

[0056] (1) 1 g of nano Fe2O3 template agent and 100 mg of polyethyleneimine were mixed and dispersed in deionized water, and stirred for 1 h to form a surface coating modification of polyethyleneimine on the nano Fe2O3 particles. 200 mg of phytic acid was added to the mixed solution, and stirred at 60°C for 3 h. After filtration and drying, a nano Fe2O3 template agent modified with a surface nitrogen source and a phosphorus source was obtained.

[0057] (2) 250 mg of vacuum residue was dissolved in a toluene solution, 750 mg of the obtained Fe2O3 template agent modified with a nitrogen source and a phosphorus source was added, and ultrasonic dispersion was performed for 30 min. The toluene solvent was evaporated at 90°C to obtain a solid mixture of vacuum residue coated Fe2O3 template agent.

[0058] (3) The solid mixture of vacuum residue and template agent was calcined under a nitrogen atmosphere, and the temperature was increased to 900°C at a rate of 7.5°C / min -1 and maintained for 3 h.

[0059] (4) The template agent was removed by acid washing with a hydrochloric acid solution, and washed with water until neutral. After filtration and vacuum drying, a nitrogen and phosphorus co-doped porous carbon material was obtained.

[0060] Example 2

[0061] The preparation method of the nitrogen and phosphorus co-doped porous carbon material in this example is as follows:

[0062] (1) 1 g of nano Fe2O3 template agent and 100 mg of polyethyleneimine were mixed and dispersed in deionized water, and stirred for 1 h to form a surface coating modification of polyethyleneimine on the nano Fe2O3 particles. 200 mg of phytic acid was added to the mixed solution, and stirred at 60°C for 3 h. After filtration and drying, a nano Fe2O3 template agent modified with a surface nitrogen source and a phosphorus source was obtained.

[0063] (2) 250 mg of vacuum residue was dissolved in a toluene solution, 750 mg of the obtained Fe2O3 template agent modified with a nitrogen source and a phosphorus source was added, and ultrasonic dispersion was performed for 30 min. The toluene solvent was evaporated at 90°C to obtain a solid mixture of vacuum residue coated Fe2O3 template agent.

[0064] (3) The mixture of deoiled pitch and template agent is calcined under nitrogen atmosphere, with a heating rate of 5℃ / min -1 to 900℃ and maintained for 3h.

[0065] (4) The template agent is removed by acid washing with hydrochloric acid solution, washed with water to neutral, filtered, vacuum dried to obtain nitrogen and phosphorus co-doped porous carbon material.

[0066] Example 3

[0067] A preparation method of a nitrogen and phosphorus co-doped porous carbon material, the steps are as follows:

[0068] (1) 1g of nano Fe2O3 template agent and 100mg of polyaniline are mixed and dispersed in deionized water, and stirred for 1h to form surface coating and modification of polyaniline on nano Fe2O3 particles; 200mg of phytic acid is added to the mixed solution, stirred at 60℃ for 3h, filtered and dried to obtain nano Fe2O3 template agent modified with surface nitrogen source and phosphorus source.

[0069] (2) 250mg of deoiled pitch is dissolved in toluene solution, 750mg of the obtained Fe2O3 template agent modified with nitrogen source and phosphorus source is added, and ultrasonic dispersion is performed for 30min. The toluene solvent is evaporated at 90℃ to obtain a solid mixture of deoiled pitch coated Fe2O3 template agent.

[0070] (3) The mixture of deoiled pitch and template agent is calcined under nitrogen atmosphere, with a heating rate of 5℃ / min -1 to 800℃ and maintained for 3h.

[0071] (4) The template agent is removed by acid washing with hydrochloric acid solution, washed with water to neutral, filtered, vacuum dried to obtain nitrogen and phosphorus co-doped porous carbon material.

[0072] Example 4

[0073] A preparation method of a nitrogen and phosphorus co-doped porous carbon material, the steps are as follows:

[0074] (1) 1g of nano Fe2O3 template agent and 100mg of chitosan are mixed and dispersed in deionized water, and stirred for 1h to form surface coating and modification of chitosan on nano Fe2O3 particles; 200mg of phytic acid is added to the mixed solution, stirred at 60℃ for 3h, filtered and dried to obtain nano Fe2O3 template agent modified with surface nitrogen source and phosphorus source.

[0075] (2) 250mg of deoiled pitch is dissolved in toluene solution, 750mg of the obtained Fe2O3 template agent modified with nitrogen source and phosphorus source is added, and ultrasonic dispersion is performed for 30min. The toluene solvent is evaporated at 90℃ to obtain a solid mixture of deoiled pitch coated Fe2O3 template agent.

[0076] (3) The mixture of deoiled pitch and template agent is calcined under nitrogen atmosphere, at a rate of 10℃ min -1 to 1000℃ and maintained for 3h.

[0077] (4) The template agent is removed by acid washing with hydrochloric acid solution, washed with water to neutral, filtered, vacuum dried to obtain nitrogen and phosphorus co-doped porous carbon material.

[0078] Example 5

[0079] A preparation method of a nitrogen and phosphorus co-doped porous carbon material, the steps are as follows:

[0080] (1) 1g of nano Fe2O3 template agent and 100mg of polyacrylamide are mixed and dispersed in deionized water, and stirred for 1h to form surface coating modification of polyacrylamide on nano Fe2O3 particles; 200mg of phytic acid is added to the mixed solution, stirred at 60℃ for 3h, filtered and dried to obtain nano Fe2O3 template agent modified with surface nitrogen source and phosphorus source.

[0081] (2) 250mg of deoiled pitch is dissolved in toluene solution, 750mg of the obtained Fe2O3 template agent modified with nitrogen source and phosphorus source is added, ultrasonic dispersion for 30min. The toluene solvent is evaporated at 90℃ to obtain a solid mixture of deoiled pitch coated Fe2O3 template agent.

[0082] (3) The mixture of deoiled pitch and template agent is calcined under nitrogen atmosphere, at a rate of 5℃ min -1 to 700℃ and maintained for 3h.

[0083] (4) The template agent is removed by acid washing with hydrochloric acid solution, washed with water to neutral, filtered, vacuum dried to obtain nitrogen and phosphorus co-doped porous carbon material.

[0084] Example 6

[0085] A preparation method of a nitrogen and phosphorus co-doped porous carbon material, the steps are as follows:

[0086] (1) 1g of nano Fe2O3 template agent and 100mg of polyacrylamide are mixed and dispersed in deionized water, and stirred for 1h to form surface coating modification of polyacrylamide on nano Fe2O3 particles; 200mg of phytic acid is added to the mixed solution, stirred at 60℃ for 3h, filtered and dried to obtain nano Fe2O3 template agent modified with surface nitrogen source and phosphorus source.

[0087] (2) 250mg of deoiled pitch is dissolved in toluene solution, 750mg of the obtained Fe2O3 template agent modified with nitrogen source and phosphorus source is added, ultrasonic dispersion for 30min. The toluene solvent is evaporated at 90℃ to obtain a solid mixture of deoiled pitch coated Fe2O3 template agent.

[0088] (3) The mixture of the deoiled pitch and the template agent is calcined under a nitrogen atmosphere at a rate of 7.5°C / min -1 to 1000°C and maintained for 3h.

[0089] (4) The template agent is removed by acid washing with a hydrochloric acid solution, washed with water until neutral, filtered, and vacuum dried to obtain the nitrogen-phosphorus co-doped porous carbon material.

[0090] Example 7

[0091] A preparation method of a nitrogen-phosphorus co-doped porous carbon material, comprising the following steps:

[0092] (1) 1g of nano Fe2O3 template agent and 100mg of polyethyleneimine are mixed and dispersed in deionized water, stirred for 1h to allow the polyethyleneimine to form a surface coating modification on the nano Fe2O3 particles; 200mg of metaphosphoric acid is added to the mixture, stirred at 60°C for 3h, filtered and dried to obtain a nano Fe2O3 template agent modified with a surface nitrogen source and a phosphorus source.

[0093] (2) 250mg of deoiled pitch is dissolved in a toluene solution, 750mg of the obtained Fe2O3 template agent modified with a nitrogen source and a phosphorus source is added, and ultrasonic dispersion is performed for 30min. The toluene solvent is evaporated at 90°C to obtain a solid mixture of deoiled pitch coated Fe2O3 template agent.

[0094] (3) The mixture of the deoiled pitch and the template agent is calcined under a nitrogen atmosphere at a rate of 5°C / min -1 to 800°C and maintained for 3h.

[0095] (4) The template agent is removed by acid washing with a hydrochloric acid solution, washed with water until neutral, filtered, and vacuum dried to obtain the nitrogen-phosphorus co-doped porous carbon material.

[0096] Comparative Example 1

[0097] (1) 250mg of hard pitch is dissolved in a toluene solution, 750mg of Fe2O3 template agent, 75mg of polyethyleneimine, and 150mg of phytic acid are added, and ultrasonic dispersion is performed for 30min. The toluene solvent is evaporated at 90°C to obtain a solid mixture of hard pitch and template agent.

[0098] (2) The mixture of the hard pitch and the template agent is calcined under a nitrogen atmosphere at a rate of 5°C / min -1 to 900°C and maintained for 3h.

[0099] (3) The template agent is removed by acid washing with a hydrochloric acid solution, washed with water until neutral, filtered, and vacuum dried to obtain the nitrogen-phosphorus co-doped porous carbon material.

[0100] Comparative Example 2

[0101] (1) 1 g nano Fe2O3 template agent and 200 mg phytic acid were mixed and dispersed in deionized water, and polyethyleneimine was allowed to form surface coating modification on the nano Fe2O3 particles by stirring for 1 h; 100 mg of polyethyleneimine was added to the mixture, and stirring reaction was carried out at 60°C for 3 h, and then the modified nano Fe2O3 template agent was obtained after filtration and drying.

[0102] (2) 250 mg of deoiled asphalt was dissolved in a toluene solution, 750 mg of the obtained nitrogen source and phosphorus source modified Fe2O3 template agent was added, and ultrasonic dispersion was carried out for 30 min. The toluene solvent was evaporated at 90°C to obtain a solid mixture of deoiled asphalt coated Fe2O3 template agent.

[0103] (3) The mixture of deoiled asphalt and template agent was calcined under a nitrogen atmosphere, and the temperature was increased to 900°C at a rate of 5°C / min -1 and maintained for 3 h.

[0104] (4) The template agent was removed by acid washing with a hydrochloric acid solution, and then washed with water until neutral. After filtration and vacuum drying, a nitrogen and phosphorus co-doped porous carbon material was obtained.

[0105] Comparative Example 3

[0106] (1) 250 mg of deoiled asphalt was dissolved in a toluene solution, 750 mg of nano Fe2O3 template agent was added, and ultrasonic dispersion was carried out for 30 min. The toluene solvent was evaporated at 90°C to obtain a solid mixture of deoiled asphalt coated Fe2O3 template agent.

[0107] (2) The mixture of deoiled asphalt and template agent was calcined under a nitrogen atmosphere, and the temperature was increased to 900°C at a rate of 5°C / min -1 and maintained for 3 h. The template agent was removed by acid washing with a hydrochloric acid solution, and then washed with water until neutral. After filtration and vacuum drying, a porous carbon material was obtained.

[0108] (3) 200 mg of the porous carbon material was mixed with 100 mg of polyethyleneimine and 200 mg of phytic acid, and then calcined under a nitrogen atmosphere, and the temperature was increased to 900°C at a rate of 5°C / min -1 and maintained for 3 h to obtain a nitrogen and phosphorus co-doped porous carbon material.

[0109] Example 8

[0110] The application of the nitrogen and phosphorus co-doped porous carbon material in electrocatalytic oxygen reduction is a three-electrode system with glass carbon (4 mm) as the working electrode, a Pt column as the counter electrode, and Ag / AgCl as the reference electrode, and the glass carbon surface is loaded with the nitrogen and phosphorus co-doped porous carbon material prepared by the method of the application.

[0111] The working electrode is prepared by mixing 2 mg of the nitrogen and phosphorus co-doped porous carbon material prepared by the method of the application as a catalyst, 5 μL of Nafion and 800 μL of ethanol, and ultrasonic treatment for 30 min to form a uniform solution. Then 15 μL of the above solution is dropped onto a glassy carbon electrode with a diameter of 4 mm (in three times) (loading amount: 0.1 mg cm -2 ).

[0112] Table 1 lists the nitrogen and phosphorus doping amounts and specific surface area results of the carbon materials prepared in Examples 1-7 and Comparative Examples 1-3 of the application.

[0113]

[0114] Table 1 lists the nitrogen and phosphorus doping amounts and specific surface area results of the carbon materials prepared in Examples 1-7 and Comparative Examples 1-3 of the application.

[0115] The TEM and LSV test results of the nitrogen and phosphorus co-doped porous carbon prepared in Examples 1-7 and Comparative Examples 1-3 of the application are shown in Figures 1-10, respectively. According to the results of the initial potential and half-wave potential, the nitrogen and phosphorus co-doped porous carbon materials obtained in Examples 1-7 have similar or better electrocatalytic oxygen reduction activity than the commercial Pt / C noble metal catalyst, while the nitrogen and phosphorus co-doped porous carbon materials obtained in Comparative Examples 1-3 have poor performance and are much worse than the commercial Pt / C noble metal catalyst. The results show that the nitrogen and phosphorus co-doped porous carbon prepared by the application has excellent electrocatalytic oxygen reduction activity.

[0116] The electrochemical performance stability test results of the nitrogen and phosphorus co-doped porous carbon prepared in Example 2 and Comparative Examples 1-3 are shown in Figure 2. Figure 11 As can be seen from the stability test, the nitrogen and phosphorus co-doped porous carbon prepared in Example 2 has excellent stability, and the catalytic effect can maintain 89% of the initial performance after 45000 s, which is better than the commercial Pt / C noble metal catalyst (73%), and far better than the nitrogen and phosphorus co-doped porous carbon prepared in Comparative Example 1 (58%), Comparative Example 2 (53%) and Comparative Example 3 (64%). The results show that the nitrogen and phosphorus co-doped porous carbon prepared by the application has excellent electrocatalytic oxygen reduction stability.

[0117] Figure 2 is a TEM element distribution map of the nitrogen and phosphorus co-doped porous carbon prepared in Example 2 of the application, wherein (a) is a TEM image, and (c)-(e) are distribution maps of N, P and C, respectively. The C, N and P element distributions are completely consistent with the material profile, indicating that the N and P elements are uniformly doped on the carbon material.

[0118] Of course, the present application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application, and these corresponding changes and modifications shall all belong to the protection scope of the present application.

Claims

1. A method for preparing heteroatom-doped porous carbon materials for electrocatalytic oxygen reduction, characterized in that, Includes the following steps: (1) Mix the template agent and nitrogen source evenly in water so that the nitrogen source coats the surface of the template agent; then add the phosphorus source and mix evenly to obtain a template agent whose surface is modified by nitrogen source and phosphorus source; (2) Using heavy oil with an asphalt content of not less than 40 wt% as the carbon source, add solvent to the carbon source and disperse it evenly by ultrasonication; then add the template agent whose surface is modified by nitrogen and phosphorus sources in step (1), evaporate the solvent in the resulting mixed solution, and take out the solid mixture. (3) The solid mixture obtained in step (2) is heated in a tube furnace under a nitrogen atmosphere at 5~10°C for min. -1 Increase the temperature and maintain a high-temperature calcination at 700~1000 ℃ for 3 hours; (4) The mixture after calcination in step (3) is acid-washed to remove the template agent, washed with water until neutral, and dried to obtain nitrogen and phosphorus co-doped porous carbon material; The nitrogen-phosphorus co-doped porous carbon material has a nitrogen content of 2-5%, a phosphorus content of 1-2%, and a specific surface area of ​​500-800 m². 2 g -1 ; The template agent is a nano-metal oxide, and the metal oxide is iron oxide.

2. The method for preparing heteroatom-doped porous carbon materials for electrocatalytic oxygen reduction according to claim 1, characterized in that, The nitrogen source is a polymer molecule containing amine groups.

3. The method for preparing heteroatom-doped porous carbon materials for electrocatalytic oxygen reduction according to claim 2, characterized in that, The nitrogen source is selected from at least one of polyaniline, chitosan, polyethyleneimine, and polyacrylamide.

4. The method for preparing heteroatom-doped porous carbon materials for electrocatalytic oxygen reduction according to claim 1, characterized in that, The phosphorus source is a molecule containing a phosphate group.

5. The method for preparing heteroatom-doped porous carbon materials for electrocatalytic oxygen reduction according to claim 4, characterized in that, The phosphorus source is selected from at least one of phytic acid, phosphoric acid, and metaphosphoric acid.

6. The method for preparing heteroatom-doped porous carbon materials for electrocatalytic oxygen reduction according to claim 1, characterized in that, The carbon source is selected from at least one of deoiled bitumen and vacuum residue.

7. The application of the heteroatom-doped porous carbon material according to any one of claims 1 to 6 as a catalyst in electrocatalytic oxygen reduction.

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