Double-doped carbon material as well as preparation method and application thereof
By preparing dual-doped carbon materials, the problem of insufficient catalytic activity of non-precious metal catalytic materials was solved, the performance and cycle life of fuel cells were improved, and efficient redox reactions were achieved.
Patent Information
- Application Number
- CN202510986499.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-17
- Publication Date
- 2025-11-18
AI Technical Summary
The insufficient catalytic activity of existing non-precious metal catalytic materials affects the performance and cycle life of fuel cells.
A method for preparing dual-doped carbon materials was adopted, in which astragalus polysaccharide, sodium persulfate and transition metal salts were reacted in a hydrothermal reactor to form transition metal-ACDs, which were then combined with aminated carbon nanotubes. After freeze-drying and sintering, nitrogen and sulfur doped carbon materials were prepared.
It improves the catalytic activity and conductivity of the catalyst, increases the specific surface area, forms a hierarchical porous structure, increases the number of active sites, reduces the charge transfer resistance, ensures rapid electron transfer in redox reactions, and reduces energy loss.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of fuel cells, in particular to a double-doped carbon material and a preparation method and application thereof. BACKGROUND
[0002] It is committed to finding clean and environmentally friendly, efficient and sustainable energy sources and energy conversion devices. High-capacity energy systems, such as fuel cells, metal-air batteries, etc., are very promising to meet the urgent needs of electric vehicles and the use of sustainable energy.
[0003] The fuel cell reaction is composed of two half-reactions of hydrogen oxidation reaction (HOR) at the anode and oxygen reduction reaction (ORR) at the cathode. The oxygen reduction reaction (ORR) on the cathode of PEMFC is slow in kinetics, which seriously affects the performance of the fuel cell. The existing platinum (Pt) based catalysts exhibit excellent performance and are essential for driving the cathode ORR. However, the high cost, scarcity and poor methanol tolerance of Pt pose a great challenge to the widespread adoption of fuel cell technology. Therefore, the development of low-cost, high-activity density center, and high-stability non-noble metal catalytic materials is crucial for the widespread promotion of low-temperature fuel cell technology. However, the catalytic activity of the non-noble metal catalytic material in the prior art is insufficient, which adversely affects the performance and cycle life of the battery. SUMMARY
[0004] The present application provides a double-doped carbon material and a preparation method and application thereof, which can solve the problem of insufficient catalytic activity of non-noble metal catalytic materials in the prior art, which adversely affects the performance and cycle life of the battery.
[0005] The object of the present application can be achieved by the following technical solutions:
[0006] In a first aspect, the present application provides a preparation method of a double-doped carbon material, comprising the following steps:
[0007] S1: Disperse Astragalus polysaccharide and sodium persulfate in deionized water, after ultrasonic treatment for 20-30 min, add transition metal salt, stir and transfer to a hydrothermal reaction kettle, after reaction, naturally cool to room temperature, centrifuge the reaction solution, dialyze for 24 h, concentrate to obtain transition metal-ACDs;
[0008] Wherein, the amount ratio of Astragalus polysaccharide, sodium persulfate, deionized water and transition metal salt is 0.5g: 0.1-0.2g: 20-30mL: 0.1-0.2g;
[0009] The sodium persulfate has oxidizability, can improve the carboxyl content of the astragalus polysaccharide, is conducive to complexing with metal ions in the transition metal salt, improves the dispersibility of the metal ions, and thus improves the catalytic activity of the catalyst, and the sodium persulfate can make the final obtained carbon material doped with sulfur elements.
[0010] S2: Amino-functionalized carbon nanotubes are prepared;
[0011] S3: The amino-functionalized carbon nanotubes and the transition metal-ACDs are dispersed in an ethanol aqueous solution, the pH is adjusted to 7-8, and after stirring for 2-3 h, freeze-drying and sintering under an inert atmosphere are performed to obtain the double-doped carbon material.
[0012] The amino-functionalized carbon nanotubes, the transition metal-ACDs and the ethanol aqueous solution are used in a ratio of 0.5-0.7 g:0.3-0.5 g:80-120 mL; and the volume ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution is 1:1.
[0013] In the above step, there is an adsorption action between the amino groups in the amino-functionalized carbon nanotubes and the metal ions of the transition metal-ACDs, which can make the amino-functionalized carbon nanotubes uniformly wrapped on the transition metal-ACDs, improve the conductivity of the catalyst, and after sintering, nitrogen-doped carbon material can be obtained.
[0014] Further, in step S1, the transition metal salt is one or several of cobalt nitrate, zinc nitrate, iron nitrate or ferrous sulfate.
[0015] Further, in step S1, the reaction temperature of the hydrothermal reaction kettle is 170-180℃, and the reaction time is 4-7 h.
[0016] Further, in step S2, the preparation steps of the amino-functionalized carbon nanotubes are as follows:
[0017] A1: Carbon nanotubes are dispersed in a mixed acid composed of concentrated sulfuric acid and concentrated nitric acid, ultrasonic treatment is performed for 2-5 h, washing and drying are performed to obtain oxidized carbon nanotubes;
[0018] The carbon nanotubes and the mixed acid are used in a ratio of 0.14 g:80-100 mL; and the volume ratio of the concentrated sulfuric acid to the concentrated nitric acid in the mixed acid is 1:(1-5).
[0019] A2: The oxidized carbon nanotubes, sodium hypochlorite and urea are added to dimethylacetamide, heating is performed to 120-150℃ for heat preservation reaction, the solid product is washed and dried to obtain amino-functionalized carbon nanotubes.
[0020] The oxidized carbon nanotubes, sodium hypochlorite, urea and dimethylacetamide are used in a ratio of 0.12 g:0.12-0.24 g:5-10 mL:100 mL.
[0021] Further, in step S3, the inert gas is any one of nitrogen, argon, and helium.
[0022] Further, in step S3, the sintering temperature is 600-750℃, the sintering time is 1-2h, and the heating rate is 2-5℃ / min.
[0023] In a second aspect, the present application provides a double-doped carbon material prepared by the method for preparing a double-doped carbon material according to any one of the above.
[0024] In a third aspect, the present application provides an application of the double-doped carbon material in a cathode catalyst of a fuel cell.
[0025] The beneficial effects of the present application are as follows:
[0026] 1. The transition metal in the double-doped carbon material prepared by the present application can be uniformly dispersed in the carbon material, thereby improving the catalytic activity of the carbon material. The aminated carbon nanotube can also uniformly wrap the transition metal-ACDs, improving the electrical conductivity of the catalyst,
[0027] 2. The aminated carbon nanotube itself has good electrical conductivity and can construct a continuous electron transport network as a carrier. At the same time, nitrogen and sulfur doping can further adjust the electron cloud density of the carbon skeleton, reduce the charge transfer resistance, ensure the rapid transfer of electrons in the oxidation-reduction reaction process, reduce energy loss, and improve the catalytic activity and electrical conductivity of the catalyst.
[0028] 3. After the aminated carbon nanotube (ACDs) derived from astragalus polysaccharide is compounded with the carbon nanotube, a multi-level pore structure can be formed to increase the specific surface area. At the same time, the structural defects introduced by nitrogen and sulfur doping further increase the number of active sites, thereby improving the electrocatalytic activity.
[0029] 4. The raw materials of the present application include natural products such as astragalus polysaccharide, sodium persulfate, transition metal salt (non-noble metal), and carbon nanotube, which avoids the use of noble metal Pt. The preparation process is simple and controllable, does not require complex equipment, and is easy to industrialize. DETAILED DESCRIPTION
[0030] The specific embodiments of the present application are described in detail below, but it should be understood that the protection scope of the present application is not limited by the specific embodiments.
[0031] Example 1
[0032] A method for preparing a double-doped carbon material includes the following steps:
[0033] S1: 0.5g astragalus polysaccharide, 0.1g sodium persulfate was dispersed in 20mL deionized water, after ultrasonic for 20min, 0.1g zinc nitrate was added, after stirring, it was transferred to the hydrothermal reactor, reacted at 170℃ for 6h, after reaction, it was naturally cooled to room temperature, the reaction solution was centrifuged, dialyzed for 24h, concentrated, and transition metal-ACDs were obtained;
[0034] S2: amino-functionalized carbon nanotubes were prepared;
[0035] S3: 0.5g amino-functionalized carbon nanotubes and 0.3g zinc-ACDs were dispersed in 100mL ethanol aqueous solution, the volume ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution was 1:1, the pH was adjusted to 7-8, after stirring for 3h, freeze-drying was carried out, sintering was carried out under nitrogen atmosphere, the sintering temperature was 600℃, the sintering time was 1h, and the heating rate was 2℃ / min, and a double-doped carbon material was obtained.
[0036] The preparation steps of the amino-functionalized carbon nanotubes are as follows:
[0037] A1: 0.14g carbon nanotubes were dispersed in 80mL mixed acid composed of concentrated sulfuric acid and concentrated nitric acid, the volume ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid was 1:1, ultrasonic was carried out for 2h, washing and drying were carried out, and oxidized carbon nanotubes were obtained;
[0038] A2: 0.12g oxidized carbon nanotubes, 0.12g sodium hypochlorite and 5mL urea were added to 100mL dimethylacetamide, heating was carried out to 120℃ for reaction, the solid product was washed and dried, and amino-functionalized carbon nanotubes were obtained.
[0039] Example 2
[0040] A preparation method of a double-doped carbon material, comprising the following steps:
[0041] S1: 0.5g astragalus polysaccharide, 0.1g sodium persulfate was dispersed in 20mL deionized water, after ultrasonic for 20min, 0.1g cobalt nitrate was added, after stirring, it was transferred to the hydrothermal reactor, reacted at 170℃ for 6h, after reaction, it was naturally cooled to room temperature, the reaction solution was centrifuged, dialyzed for 24h, concentrated, and transition metal-ACDs were obtained;
[0042] S2: amino-functionalized carbon nanotubes were prepared;
[0043] S3: 0.5g amino-functionalized carbon nanotubes and 0.3g cobalt-ACDs were dispersed in 100mL ethanol aqueous solution, the volume ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution was 1:1, the pH was adjusted to 7-8, after stirring for 3h, freeze-drying was carried out, sintering was carried out under nitrogen atmosphere, the sintering temperature was 600℃, the sintering time was 1h, and the heating rate was 2℃ / min, and a double-doped carbon material was obtained.
[0044] The preparation steps of the aminated carbon nanotube are as follows:
[0045] A1: 0.14 g of carbon nanotubes is dispersed in 80 mL of mixed acid composed of concentrated sulfuric acid and concentrated nitric acid, the volume ratio of concentrated sulfuric acid and concentrated nitric acid in the mixed acid is 1:1, ultrasonic treatment is performed for 2 h, washing and drying are performed, and oxidized carbon nanotubes are obtained;
[0046] A2: 0.12 g of the oxidized carbon nanotubes, 0.12 g of sodium nitrite, and 5 mL of urea are added to 100 mL of dimethylacetamide, heating is performed to 120°C for reaction, the solid product is washed and dried, and the aminated carbon nanotube is obtained.
[0047] Example 3
[0048] A preparation method of a double-doped carbon material, comprising the following steps:
[0049] S1: 0.5 g of astragalus polysaccharide and 0.12 g of sodium persulfate are dispersed in 20 mL of deionized water, ultrasonic treatment is performed for 30 min, then 0.12 g of cobalt nitrate is added, stirring is performed, and then the mixture is transferred to a hydrothermal reaction kettle, reaction is performed at 180°C for 6 h, after the reaction is completed, natural cooling is performed to room temperature, the reaction solution is centrifuged, dialysis is performed for 24 h, and concentration is performed, and a transition metal-ACD is obtained;
[0050] S2: the aminated carbon nanotube is prepared;
[0051] S3: 0.5 g of the aminated carbon nanotube and 0.3 g of the transition metal-ACD are dispersed in 100 mL of an ethanol aqueous solution, the volume ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution is 1:1, the pH value is adjusted to 7-8, stirring is performed for 3 h, freeze drying is performed, sintering is performed under a nitrogen atmosphere, the sintering temperature is 750°C, the sintering time is 2 h, the temperature rising rate is 5°C / min, and a double-doped carbon material is obtained.
[0052] The preparation steps of the aminated carbon nanotube are as follows:
[0053] A1: 0.14 g of carbon nanotubes is dispersed in 80 mL of mixed acid composed of concentrated sulfuric acid and concentrated nitric acid, the volume ratio of concentrated sulfuric acid and concentrated nitric acid in the mixed acid is 1:1, ultrasonic treatment is performed for 5 h, washing and drying are performed, and oxidized carbon nanotubes are obtained;
[0054] A2: 0.12 g of the oxidized carbon nanotubes, 0.18 g of sodium nitrite, and 7.5 mL of urea are added to 100 mL of dimethylacetamide, heating is performed to 140°C for reaction, the solid product is washed and dried, and the aminated carbon nanotube is obtained.
[0055] Example 4
[0056] Compared with Example 2, the use amount of sodium persulfate and cobalt nitrate is increased in the preparation method of the double-doped carbon material.
[0057] S1: 0.5g of astragalus polysaccharide, 0.15g of sodium persulfate was dispersed in 20mL of deionized water, after ultrasonic for 30min, 0.15g of cobalt nitrate was added, after stirring, it was transferred to the hydrothermal reaction kettle, reacted at 180℃ for 6h, after the reaction was completed, it was naturally cooled to room temperature, the reaction solution was centrifuged, dialyzed for 24h, concentrated, and transition metal-ACDs were obtained;
[0058] S2: Aminated carbon nanotubes were prepared;
[0059] S3: 0.5g of aminated carbon nanotubes and 0.3g of transition metal-ACDs were dispersed in 100mL of ethanol aqueous solution, the volume ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution was 1:1, the pH was adjusted to 7-8, after stirring for 3h, it was freeze-dried, sintered under nitrogen atmosphere, the sintering temperature was 750℃, the sintering time was 2h, and the heating rate was 5℃ / min, and a double-doped carbon material was obtained.
[0060] The preparation steps of the aminated carbon nanotubes are:
[0061] A1: 0.14g of carbon nanotubes was dispersed in 80mL of mixed acid composed of concentrated sulfuric acid and concentrated nitric acid, the volume ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid was 1:1, ultrasonic was performed for 5h, washed, and dried to obtain oxidized carbon nanotubes;
[0062] A2: 0.12g of oxidized carbon nanotubes, 0.24g of sodium hypochlorite and 10mL of urea were added to 100mL of dimethylacetamide, heated to 150℃ for reaction, the solid product was washed and dried to obtain aminated carbon nanotubes.
[0063] Example 5
[0064] A preparation method of a double-doped carbon material, comprising the following steps:
[0065] S1: 0.5g of astragalus polysaccharide, 0.17g of sodium persulfate was dispersed in 30mL of deionized water, after ultrasonic for 30min, 0.17g of cobalt nitrate was added, after stirring, it was transferred to the hydrothermal reaction kettle, reacted at 180℃ for 6h, after the reaction was completed, it was naturally cooled to room temperature, the reaction solution was centrifuged, dialyzed for 24h, concentrated, and transition metal-ACDs were obtained;
[0066] S2: Aminated carbon nanotubes were prepared;
[0067] S3: 0.6 g of the aminated carbon nanotubes and 0.4 g of the transition metal-ACDs were dispersed in 100 mL of an ethanol aqueous solution, the volume ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution was 1:1, the pH was adjusted to 7-8, and after stirring for 3 h, freeze-drying was performed, sintering was performed under a nitrogen atmosphere, the sintering temperature was 750 DEG C, the sintering time was 2 h, the temperature increase rate was 5 DEG C / min, and a double-doped carbon material was obtained.
[0068] The preparation steps of the aminated carbon nanotubes are as follows:
[0069] A1: 0.14 g of carbon nanotubes were dispersed in 80-100 mL of a mixed acid composed of concentrated sulfuric acid and concentrated nitric acid, the volume ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid was 1:1, ultrasonic treatment was performed for 5 h, washing and drying were performed, and oxidized carbon nanotubes were obtained;
[0070] A2: 0.12 g of the oxidized carbon nanotubes, 0.24 g of sodium hyposulfite, and 10 mL of urea were added to 100 mL of dimethylacetamide, heating was performed to 150 DEG C for reaction, the solid product was washed and dried, and aminated carbon nanotubes were obtained.
[0071] Example 6
[0072] A preparation method of a double-doped carbon material comprises the following steps:
[0073] S1: 0.5 g of astragalus polysaccharide and 0.2 g of sodium persulfate were dispersed in 20 mL of deionized water, after ultrasonic treatment for 30 min, 0.2 g of cobalt nitrate was added, stirring was performed, and then the mixture was transferred to a hydrothermal reaction kettle, reaction was performed at 180 DEG C for 6 h, after the reaction was completed, natural cooling was performed to room temperature, the reaction liquid was centrifuged, dialysis was performed for 24 h, and concentration was performed, and transition metal-ACDs were obtained;
[0074] S2: aminated carbon nanotubes were prepared;
[0075] S3: 0.7 g of the aminated carbon nanotubes and 0.5 g of the transition metal-ACDs were dispersed in 100 mL of an ethanol aqueous solution, the volume ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution was 1:1, the pH was adjusted to 7-8, and after stirring for 3 h, freeze-drying was performed, sintering was performed under a nitrogen atmosphere, the sintering temperature was 750 DEG C, the sintering time was 2 h, the temperature increase rate was 5 DEG C / min, and a double-doped carbon material was obtained.
[0076] The preparation steps of the aminated carbon nanotubes are as follows:
[0077] A1: 0.14 g of carbon nanotubes were dispersed in 80 mL of a mixed acid composed of concentrated sulfuric acid and concentrated nitric acid, the volume ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid was 1:1, ultrasonic treatment was performed for 5 h, washing and drying were performed, and oxidized carbon nanotubes were obtained;
[0078] A2: 0.12 g of oxidized carbon nanotubes, 0.24 g of sodium nitrite and 10 mL of urea were added to 100 mL of dimethylacetamide, heated to 150°C for reaction, and the solid product was washed and dried to obtain amino carbon nanotubes.
[0079] Comparative Example 1
[0080] The comparative example is compared with Example 1, the difference is that the amino carbon nanotubes are replaced by carbon nanotubes, and the specific steps are as follows:
[0081] S1: 0.5 g of astragalus polysaccharide and 0.1 g of sodium persulfate were dispersed in 20 mL of deionized water, and after ultrasonic treatment for 20 min, 0.1 g of zinc nitrate was added, stirred and transferred to a hydrothermal reaction kettle, reacted at 170°C for 6 h, and after the reaction was completed, it was naturally cooled to room temperature, the reaction solution was centrifuged, dialyzed for 24 h, concentrated, and transition metal-ACDs were obtained.
[0082] S2: 0.5 g of carbon nanotubes and 0.3 g of zinc-ACDs were dispersed in 100 mL of an ethanol aqueous solution, the volume ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution was 1:1, the pH was adjusted to 7-8, and after stirring for 3 h, freeze-drying was performed, sintering was performed under a nitrogen atmosphere, the sintering temperature was 600°C, the sintering time was 1 h, and the heating rate was 2°C / min, to obtain a double-doped carbon material.
[0083] The remaining raw materials and steps are the same as in Example 1.
[0084] Comparative Example 2
[0085] The comparative example is compared with Example 1, the difference is that the sodium persulfate is omitted, and the specific steps are as follows:
[0086] S1: 0.5 g of astragalus polysaccharide was dispersed in 20 mL of deionized water, and after ultrasonic treatment for 20 min, 0.1 g of zinc nitrate was added, stirred and transferred to a hydrothermal reaction kettle, reacted at 170°C for 6 h, and after the reaction was completed, it was naturally cooled to room temperature, the reaction solution was centrifuged, dialyzed for 24 h, concentrated, and transition metal-ACDs were obtained.
[0087] S2: Amino carbon nanotubes were prepared.
[0088] S3: 0.5 g of amino carbon nanotubes and 0.3 g of zinc-ACDs were dispersed in 100 mL of an ethanol aqueous solution, the volume ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution was 1:1, the pH was adjusted to 7-8, and after stirring for 3 h, freeze-drying was performed, sintering was performed under a nitrogen atmosphere, the sintering temperature was 600°C, the sintering time was 1 h, and the heating rate was 2°C / min, to obtain a double-doped carbon material.
[0089] The remaining raw materials and steps are the same as in Example 1.
[0090] Comparative Example 3
[0091] The present comparative example differs from Example 1 in that the aminated carbon nanotubes are omitted, and the specific steps are as follows:
[0092] 0.5 g of astragalus polysaccharide and 0.1 g of sodium persulfate were dispersed in 20 mL of deionized water, and after ultrasonic treatment for 20 min, 0.1 g of zinc nitrate was added. After stirring, it was transferred to a hydrothermal reaction kettle and reacted at 170°C for 6 h. After the reaction was completed, it was naturally cooled to room temperature, and the reaction solution was centrifuged, dialyzed for 24 h, concentrated, dried, and sintered under a nitrogen atmosphere. The sintering temperature was 600°C, the sintering time was 1 h, and the heating rate was 2°C / min. A double-doped carbon material was obtained.
[0093] The remaining raw materials and steps are the same as in Example 1.
[0094] Comparative Example 4
[0095] The present comparative example differs from Example 1 in that the aminated carbon nanotubes and sodium persulfate are omitted, and the specific steps are as follows:
[0096] 0.5 g of astragalus polysaccharide was dispersed in 20 mL of deionized water, and after ultrasonic treatment for 20 min, 0.1 g of zinc nitrate was added. After stirring, it was transferred to a hydrothermal reaction kettle and reacted at 170°C for 6 h. After the reaction was completed, it was naturally cooled to room temperature, and the reaction solution was centrifuged, dialyzed for 24 h, concentrated, dried, and sintered under a nitrogen atmosphere. The sintering temperature was 600°C, the sintering time was 1 h, and the heating rate was 2°C / min. A double-doped carbon material was obtained.
[0097] The remaining raw materials and steps are the same as in Example 1.
[0098] The double-doped carbon materials prepared in Examples 1-5 and Comparative Examples 1-4 were coated onto a glassy carbon electrode for catalytic testing. A saturated calomel electrode was used as the reference electrode, a platinum wire electrode was used as the counter electrode, and the glassy carbon electrode coated with the catalyst sample was used as the working electrode. The working electrode was prepared as follows: the catalyst was prepared into a mixed solution of deionized water and anhydrous ethanol (1:1) with a concentration of 5 mg / ml, and after ultrasonic treatment for 10 min, 8 μL (in two portions, 4 μL each) was transferred to a polished rotating disc electrode using a micropipette. After natural air drying, 8 μL of anhydrous ethanol solution with a mass fraction of 0.05% was dropped onto the electrode surface and naturally air dried. The initial potential and half-wave potential after 3000 cycles were determined by cyclic voltammetry.
[0099]
[0100]
[0101] As can be seen from Table 1, the catalytic performance of the material prepared in Examples 1-6 is better than that of Comparative Examples 1-4.
[0102] Comparative Example 1 does not contain amino groups, and both the initial potential and the half-wave potential are lower than those of Example 1, indicating that the amino-functionalized carbon nanotubes can obtain nitrogen-doped carbon materials after sintering, and the nitrogen doping can further adjust the electron cloud density of the carbon skeleton, reduce the charge transfer resistance, ensure the rapid transfer of electrons in the redox reaction process, reduce energy loss, and improve the catalytic activity and conductivity of the catalyst. Moreover, the amino groups in the amino-functionalized carbon nanotubes have an adsorption effect with the metal ions of the transition metal-ACDs, which can make the amino-functionalized carbon nanotubes uniformly wrap the transition metal-ACDs, thereby improving the conductivity of the catalyst.
[0103] Comparative Example 2 does not contain sodium persulfate, and both the initial potential and the half-wave potential are lower than those of Example 1, indicating that sodium persulfate has oxidizing properties, which can increase the carboxyl content of astragalus polysaccharide, which is conducive to the complexation with metal ions in the transition metal salt, thereby improving the dispersity of the metal ions, and improving the catalytic activity of the catalyst. Moreover, sodium persulfate can make the final obtained carbon material doped with sulfur elements. Sulfur doping can further adjust the electron cloud density of the carbon skeleton, reduce the charge transfer resistance, ensure the rapid transfer of electrons in the redox reaction process, reduce energy loss, and improve the catalytic activity and conductivity of the catalyst.
[0104] Comparative Example 3 does not contain amino-functionalized carbon nanotubes, and although the carbon material is doped with sulfur elements, the overall conductivity is decreased due to the absence of carbon nanotubes, and it is not easy to form a porous structure, so the catalytic performance is lower than that of Example 1.
[0105] The above disclosure is only a few specific embodiments of the present application, but the embodiments of the present application are not limited thereto, and any changes that can be thought of by those skilled in the art should fall within the protection scope of the present application.
Claims
1. A method for preparing a dual-doped carbon material, characterized in that, Includes the following steps: S1: Disperse Astragalus polysaccharide and sodium persulfate in deionized water, sonicate for 20-30 min, add transition metal salt, stir and transfer to a hydrothermal reactor. After the reaction is completed, cool naturally to room temperature, centrifuge, dialyze for 24 h, concentrate to obtain transition metal-ACDs; S2: Aminated carbon nanotubes were prepared; S3: Aminated carbon nanotubes and transition metal-ACDs are dispersed in an aqueous ethanol solution, the pH is adjusted to 7-8, stirred for 2-3 hours, freeze-dried, and sintered under an inert atmosphere to obtain a dual-doped carbon material.
2. The method for preparing a dual-doped carbon material according to claim 1, characterized in that, In step S1, the ratio of Astragalus polysaccharide, sodium persulfate, deionized water, and transition metal salt is 0.5g: 0.1-0.2g: 20-30mL: 0.1-0.2g.
3. The method for preparing a dual-doped carbon material according to claim 1, characterized in that, In step S1, the transition metal salt is one or more of cobalt nitrate, zinc nitrate, ferric nitrate, or ferrous sulfate; The reaction temperature in the hydrothermal reactor is 170-180℃, and the reaction time is 4-7 hours.
4. The method for preparing a dual-doped carbon material according to claim 1, characterized in that, In step S2, the preparation steps of aminated carbon nanotubes are as follows: A1: Disperse carbon nanotubes in a mixed acid composed of concentrated sulfuric acid and concentrated nitric acid, sonicate for 2-5 hours, wash, and dry to obtain carbon nanotube oxide. A2: Carbon nanotubes, sodium hyponitrate and urea are added to dimethylacetamide and heated to 120-150℃ for reaction. The solid product is washed and dried to obtain amino carbon nanotubes.
5. The method for preparing a dual-doped carbon material according to claim 4, characterized in that, In step A1, the ratio of carbon nanotubes to mixed acid is 0.14g:80-100mL; the volume ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid is 1:(1-5).
6. The method for preparing a dual-doped carbon material according to claim 4, characterized in that, In step A2, the ratio of carbon nanotubes, sodium hyponitrate, urea, and dimethylacetamide is 0.12g:0.12-0.24g:5-10mL:100mL.
7. The method for preparing a dual-doped carbon material according to claim 1, characterized in that, In step S3, the inert gas is any one of nitrogen, argon, or helium; The sintering temperature is 600-750℃, the sintering time is 1-2h, and the heating rate is 2-5℃ / min.
8. The method for preparing a dual-doped carbon material according to claim 1, characterized in that, In step S3, the ratio of aminated carbon nanotubes, transition metal-ACDs, and ethanol aqueous solution is 0.5-0.7g: 0.3-0.5g: 80-120mL; the volume ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution is 1:
1.
9. A dual-doped carbon material, characterized in that, It is prepared by the method for preparing the dual-doped carbon material according to any one of claims 1-8.
10. The application of the dual-doped carbon material according to claim 9 in the cathode catalyst of a fuel cell.