Sulfur-nitrogen co-doped hollow carbon nanoring and preparation method thereof

Abstract

The invention discloses a sulfur-nitrogen co-doped hollow carbon nanoring and a preparation method thereof, and belongs to the technical field of new nano materials. The method comprises the following steps: by taking melamine and fatty aldehyde as raw materials, aromatic amine-acid as a reaction initiator and a cross-linking agent and an anionic surfactant and a zwitterionic surfactant as template agents, constructing nano-micelles based on the synergistic interaction of the dual surfactants; the preparation method comprises the following steps: introducing protonated melamine as an organic counter ion into a system, reducing electrostatic repulsion between hydrophilic groups of an anionic surfactant so as to adjust micelle accumulation parameters, and enabling the surfactant micelle to be converted from a spherical shape to a rod shape and then to a ring shape by adjusting the amount of melamine; and adding formaldehyde to initiate a Schiff base addition polymerization reaction to obtain a hollow polymer nanoring, and roasting at high temperature in an inert gas atmosphere to obtain the sulfur-nitrogen co-doped hollow carbon nanoring. The synthesis method disclosed by the invention is simple to operate, mild in process condition and relatively low in cost, and effectively realizes accurate control on a target product.

Description

Technical Field

[0001] The invention belongs to the technical field of new nano materials, and particularly relates to a sulfur-nitrogen co-doped hollow carbon nanoring and a preparation method thereof. Background Art

[0002] Carbon materials have excellent mechanical properties, electrical conductivity, chemical stability and light weight, and are widely used in energy, environment, electronics and catalysis. Through heteroatom doping and morphology control, their physical and chemical properties can be further optimized and their application areas can be broadened. The doping of N elements can adjust the electronic structure of the material and improve the electrochemical properties of the material. The doping of S will increase the interlayer spacing of the carbon material, which is more conducive to mass transfer. Morphology control enhances the specific surface area and mass transfer performance. One-dimensional hollow carbon materials have high specific surface area, excellent electrical conductivity, good mechanical strength and adjustable chemical properties. The combination of the two provides an important way to improve the high performance and multifunctionality of carbon materials.

[0003] Hollow carbon nanorings not only inherit the characteristics of low cost and relative stability of carbon materials, but the hollow structure also provides a larger specific surface area and can provide more active sites. At the same time, the ring structure can exhibit unique optical, magnetic and electronic properties that are highly related to its scale, providing more diverse options for advanced nanoreactors.

[0004] At present, hollow carbon nanostructures are often synthesized using the template method. The reported synthesis methods have disadvantages such as harsh conditions, cumbersome steps, and low yield, which to a certain extent limit their large-scale commercial applications. At the same time, the traditional template method is also difficult to achieve multiple goals such as morphology control, pore construction, and heteroatom doping in one step, and often requires multiple steps to achieve the goal, which undoubtedly makes the experimental steps cumbersome and increases costs. Summary of the invention

[0005] The present invention provides a method for synthesizing a one-dimensional hollow carbon nanoring with simple operation and mild conditions, which can simultaneously achieve the control of multiple goals of morphology control, pore construction and heteroatom doping, so as to solve the problems of high cost, harsh conditions and complicated steps in the production of hollow carbon nanorings in the prior art.

[0006] Nanomicelles are constructed based on the synergistic effect of dual surfactants, using melamine and fatty aldehyde as raw materials, aromatic amine-acid as reaction initiator and cross-linking agent, anionic surfactant and zwitterionic surfactant as templates; protonated melamine is introduced into the system as an organic counterion to reduce the electrostatic repulsion between the hydrophilic groups of the anionic surfactant, thereby adjusting the micelle stacking parameters, and the surfactant micelles are transformed from spherical to rod-shaped and then to ring-shaped by adjusting the amount of melamine; formaldehyde is added to initiate the Schiff base addition polymerization reaction to obtain hollow polymer nanorings, which are then calcined at high temperature in an inert gas atmosphere to obtain sulfur-nitrogen co-doped hollow carbon nanorings.

[0007] The technical solution adopted by the present invention is: a method for preparing sulfur-nitrogen co-doped hollow carbon nanorings, comprising the following steps: (1) stirring and mixing anionic surfactant and amphoteric surfactant in an aqueous phase; (2) adding melamine and aromatic amine-acid into water and dissolving them uniformly; the amount of aromatic amine-acid used is 5% to 40% of the molar amount of melamine; (3) mixing the solutions of step (1) and step (2), and continuing to stir to construct a composite micelle system; (4) Add formaldehyde, react for 10-120 min, and centrifuge to obtain a solid; (5) Sulfur-nitrogen co-doped hollow carbon nanorings were obtained by calcination under an inert atmosphere.

[0008] Furthermore, the aromatic amine-acid is one of 2,4-diaminobenzenesulfonic acid, 2,5-diaminobenzenesulfonic acid, 3,5-diaminobenzenesulfonic acid, o-aminobenzenesulfonic acid, m-aminobenzenesulfonic acid, p-aminobenzenesulfonic acid, and m-phenylenediamine disulfonic acid.

[0009] Furthermore, the anionic surfactant is one of sodium bis(2-ethylhexyl)sulfosuccinate, sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.

[0010] Furthermore, the zwitterionic surfactant is one of cocamidopropyl betaine, dodecyl dimethyl betaine, and 3-sulfopropyl dodecyl dimethyl betaine.

[0011] Furthermore, the molar ratio of the anionic surfactant and the amphoteric surfactant when compounded is 1: 1. The amount of the anionic surfactant and the amphoteric surfactant used is greater than 0 and less than the critical micelle concentration.

[0012] Furthermore, the amount of the surfactant is 1% to 10% of the molar amount of melamine.

[0013] Furthermore, the formaldehyde dosage is 1-3 mL.

[0014] Furthermore, the gas used in the inert atmosphere is nitrogen or argon, the carbonization temperature is 600-800° C., and the time is 80-120 min.

[0015] A sulfur-nitrogen co-doped hollow carbon nanoring is prepared by the above preparation method.

[0016] Furthermore, the size of the nano ring is 3-5 μm. The nitrogen content of the hollow carbon nano ring is 7%-20%, and the sulfur content is 1.2%-3%.

[0017] Specifically, a sulfur-nitrogen co-doped hollow carbon nanoring and a preparation method thereof, the method comprising the following steps: (1) dissolving anionic surfactant and zwitterionic surfactant in water system, stirring vigorously for 0.5-5h, and completing compounding: the molar ratio of the anionic surfactant to the zwitterionic surfactant is 1:1; (2) Dissolve melamine and aromatic amine-acid in water system and stir with the prepared surfactant solution. The mixing time should be 20-120 min. (3) adding formaldehyde, reacting at 10-30°C for 20-180 min, and centrifuging to obtain hollow polymer nanorings; (4) High temperature calcination under an inert atmosphere to obtain sulfur-nitrogen co-doped hollow carbon nanorings.

[0018] The present invention provides a sulfur-nitrogen co-doped hollow carbon nanoring and a preparation method thereof. The sulfur-nitrogen co-doped hollow carbon nanoring has a carbonization capacity of 744 cm 2 g -1 of carbon dioxide, 7.2 wt% nitrogen content, 2.4 wt% sulfur content and used as supercapacitor electrode material.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. The synthetic method adopted in the present invention has mild conditions, can stably react at 10-30°C, and reacts rapidly, turbidity of the system can be observed in ~10 s, and the reaction can be stopped as needed within 10-120 min.

[0020] 2. The sulfur-nitrogen co-doped hollow carbon nanorings synthesized in the present invention have a carbon content of 744 cm without further activation treatment. 2 g -1 Specific surface area.

[0021] 3. Compared with the traditional preparation process of hollow carbon nanoring materials, the present invention has the characteristics of simple operation, mild conditions, and is conducive to large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 SEM and TEM images of sulfur-nitrogen co-doped hollow polymer nanorings.

[0023] Figure 2 This is the SEM image of the polymerization product when no surfactant is added.

[0024] Figure 3 This is the SEM image of the polymerization product when only AOT is added as a template.

[0025] Figure 4 This is the SEM image of the polymerization product when only SB-12 is added as a template.

[0026] Figure 5 SEM images of sulfur-nitrogen co-doped hollow polymer nanorings prepared at different reaction times.

[0027] Figure 6 SEM images of sulfur-nitrogen co-doped hollow polymer nanorings prepared with different melamine addition amounts.

[0028] Figure 7 SEM images of sulfur-nitrogen co-doped hollow polymer nanorings prepared with different amounts of 2,4-diaminobenzenesulfonic acid added.

[0029] Figure 8 SEM image of sulfur-nitrogen co-doped hollow polymer nanorings prepared to scale up the reaction system 4 times.

[0030] Fig. 9 This is the SEM image of the polymer product obtained by compounding F127 and SB-12.

[0031] Fig.10 SEM images, TEM images and element distribution maps of sulfur-nitrogen co-doped hollow carbon nanorings.

[0032] Fig.11 This is the specific capacitance curve of sulfur-nitrogen co-doped hollow carbon nanorings obtained by carbonization at 600°C.

[0033] Fig.12 This is the specific capacitance curve of sulfur-nitrogen co-doped hollow carbon nanorings obtained by carbonization at 700°C.

[0034] Fig.13 This is the specific capacitance curve of sulfur-nitrogen co-doped hollow carbon nanorings obtained by carbonization at 800°C.

[0035] Fig.14 This is the cycling performance diagram of sulfur-nitrogen co-doped hollow carbon nanorings obtained by carbonization at 700°C.

[0036] Fig.15 Nitrogen adsorption / desorption isotherms were performed for Examples 11, 12, and 13. DETAILED DESCRIPTION

[0037] The following non-limiting embodiments may enable a person skilled in the art to more fully understand the present invention, but do not limit the present invention in any way.

[0038] The instruments, reagents, materials, etc. involved in the following examples, unless otherwise specified, are all conventional instruments, reagents, materials, etc. in the prior art and can be obtained through regular commercial channels. The experimental methods, detection methods, etc. involved in the following examples, unless otherwise specified, are all conventional experimental methods, detection methods, etc. in the prior art. Example 1

[0039] At room temperature, 0.044 g (0.1 mmol) of AOT was completely dissolved in 10 mL of deionized water with 0.034 g of SB-12 (0.1 mmol) and stirred vigorously for 0.5 h, which was recorded as solution A. 0.4 g (3.2 mmol) of melamine and 0.132 g of 2,4-diaminobenzenesulfonic acid (0.7 mmol) were completely dissolved in 60 mL of deionized water, which was recorded as solution B. After mixing and stirring the AB solutions for 1 h, 3 mL of formaldehyde was added, and the mixture was reacted for 120 min before centrifugation, washing with water, and drying. Figure 1 SEM and TEM images of the prepared thio-co-doped polymer nanorings, where a and b are SEM images, and c and d are TEM images. Example 2

[0040] At room temperature, 0.4 g (3.2 mmol) of melamine and 0.132 g of 2,4-diaminobenzenesulfonic acid (0.7 mmol) were completely dissolved in 70 mL of deionized water, and 3 mL of formaldehyde was added. After reacting for 120 min, the mixture was centrifuged, washed with water, and dried. Figure 2 This is the SEM image of the polymerization product when no surfactant is added. In the figure, it can be seen that the polymerization product is spherical rather than hollow nano-ring-shaped when no surfactant is added. Example 3

[0041] At room temperature, 0.044 g (0.1 mmol) of AOT was completely dissolved in 10 mL of deionized water, which was recorded as solution A. 0.4 g (3.2 mmol) of melamine and 0.132 g of 2,4-diaminobenzenesulfonic acid (0.7 mmol) were completely dissolved in 60 mL of deionized water, which was recorded as solution B. After the AB solutions were mixed and stirred for 1 h, 3 mL of formaldehyde was added, and the mixture was reacted for 120 min before centrifugation, washing, and drying. Figure 3 This is the SEM image of the polymerization product when only AOT was added. Example 4

[0042] At room temperature, 0.034 g of SB-12 (0.1 mmol) was completely dissolved in 10 mL of deionized water, which was recorded as solution A. 0.4 g (3.2 mmol) of melamine and 0.132 g of 2,4-diaminobenzenesulfonic acid (0.7 mmol) were completely dissolved in 60 mL of deionized water, which was recorded as solution B. After mixing and stirring the AB solutions for 1 h, 3 mL of formaldehyde was added, and the mixture was reacted for 120 min, centrifuged, washed with water, and dried. Figure 4 The SEM image of the polymerized product when only SB-12 was added. Figure 3 and Figure 4It can be seen that when only one surfactant is added, the polymerization product presents an irregular spherical shape. The synergistic effect of the two surfactants is the key to the synthesis. Example 5

[0043] At room temperature, 0.044 g (0.1 mmol) of AOT was completely dissolved in 0.034 g of SB-12 (0.1 mmol) in 10 mL of deionized water and stirred vigorously for 0.5 h, which was recorded as solution A. 0.4 g (3.2 mmol) of melamine and 0.132 g of 2,4-diaminobenzenesulfonic acid (0.7 mmol) were completely dissolved in 60 mL of deionized water, which was recorded as solution B. After mixing and stirring the AB solutions for 1 h, 3 mL of formaldehyde was added, and the mixture was reacted for 10 min, 30 min, and 60 min, then centrifuged, washed with water, and dried. Figure 5 Figures a, b, and c are SEM images of sulfur-nitrogen co-doped polymer nanorings prepared with reaction times of 10 min, 30 min, and 60 min, respectively. It can be seen that the target product can be obtained after polymerization for 10 min, proving that this method is highly efficient. Example 6

[0044] At room temperature, 0.044 g (0.1 mmol) of AOT was completely dissolved in 10 mL of deionized water with 0.034 g of SB-12 (0.1 mmol) and stirred vigorously for 0.5 h, which was recorded as solution A. 0.15 g (1.2 mmol), 0.252 g (2 mmol), 0.4 g (3.2 mmol) of melamine and 0.132 g of 2,4-diaminobenzenesulfonic acid (0.7 mmol) were completely dissolved in 60 mL of deionized water, which was recorded as solution B. After mixing and stirring the AB solutions for 1 h, 3 mL of formaldehyde was added, and the mixture was reacted for 120 min before centrifugation, washing with water, and drying. Figure 6 Figures a, b, and c are SEM images of sulfur-nitrogen co-doped polymer nanorings prepared with melamine dosages of 0.15 g (1.2 mmol), 0.252 g (2 mmol), and 0.4 g (3.2 mmol), respectively. It can be seen that with the increase in the amount of melamine, the polymer product changes from spherical to rod-shaped and finally to a ring. Therefore, when preparing sulfur-nitrogen co-doped hollow polymer nanorings, the amount of melamine should not be less than 3.2 mmol. Example 7

[0045] At room temperature, 0.044 g (0.1 mmol) of AOT was completely dissolved in 10 mL of deionized water with 0.034 g of SB-12 (0.1 mmol) and stirred vigorously for 0.5 h, which was recorded as solution A. 0.4 g (3.2 mmol) of melamine and 0.056 g (0.3 mmol), 0.094 g (0.5 mmol), 0.132 g (0.7 mmol) and 0.169 g (0.9 mmol) of 2,4-diaminobenzenesulfonic acid were completely dissolved in 60 mL of deionized water, which was recorded as solution B. After mixing and stirring the AB solutions for 1 h, 3 mL of formaldehyde was added, and the mixture was reacted for 120 min before centrifugation, washing with water and drying. Figure 7 In the figure, a, b, c, and d are SEM images of sulfur-nitrogen co-doped polymer nanorings prepared with 0.056 g (0.3 mmol), 0.094 g (0.5 mmol), 0.132 g (0.7 mmol), and 0.169 g (0.9 mmol) of 2,4-diaminobenzenesulfonic acid, respectively. The size of the obtained nanorings can be roughly adjusted by adjusting the amount of 2,4-diaminobenzenesulfonic acid. Example 8

[0046] At room temperature, 0.173 g (0.4 mmol) of AOT was completely dissolved in 40 mL of deionized water with 0.135 g of SB-12 (0.4 mmol) and stirred vigorously for 0.5 h, which was recorded as solution A. 1.6 g (12.8 mmol) of melamine and 0.536 g of 2,4-diaminobenzenesulfonic acid (2.8 mmol) were completely dissolved in 240 mL of deionized water, which was recorded as solution B. After mixing and stirring the AB solutions for 1 h, 12 mL of formaldehyde was added, and the mixture was reacted for 120 min before centrifugation, washing with water, and drying. Figure 8 SEM image of sulfur-nitrogen co-doped polymer nanorings prepared by four-fold scaling. Example 9

[0047] At room temperature, 0.127 g (0.1 mmol) of F127 was completely dissolved in 0.034 g of SB-12 (0.1 mmol) in 10 mL of deionized water and stirred vigorously for 0.5 h, which was recorded as solution A. 0.4 g (3.2 mmol) of melamine and 0.132 g of 2,4-diaminobenzenesulfonic acid (0.7 mmol) were completely dissolved in 60 mL of deionized water, which was recorded as solution B. After mixing and stirring the AB solutions for 1 h, 3 mL of formaldehyde was added, and the mixture was reacted for 120 min before centrifugation, washing with water, and drying. Fig. 9The SEM image of the prepared polymerization product. In the image, no hollow carbon nanorings are formed. Polyoxyethylene polyoxypropylene ether F127 is a nonionic surfactant. It can be seen that the anionic surfactant is the action site of protonated melamine to regulate the micelle behavior. Example 10

[0048] At room temperature, 0.173 g (0.4 mmol) of AOT was completely dissolved in 40 mL of deionized water with 0.135 g of SB-12 (0.4 mmol) and stirred vigorously for 0.5 h, which was recorded as solution A. 1.6 g (12.8 mmol) of melamine and 0.536 g of 2,4-diaminobenzenesulfonic acid (2.8 mmol) were completely dissolved in 240 mL of deionized water, which was recorded as solution B. After mixing and stirring the AB solutions for 1 h, 12 mL of formaldehyde was added, and the reaction lasted for 120 min before centrifugation, water washing, and drying. The obtained yellow solid was placed in a tubular furnace and carbonized at 700 ° C for 120 min under a nitrogen atmosphere. Fig.10 a and b are SEM images of sulfur-nitrogen co-doped carbon nanorings, c and d are TEM images, and e~h are element distributions. Embodiment 11

[0049] At room temperature, 0.173 g (0.4 mmol) of AOT was completely dissolved in 40 mL of deionized water with 0.135 g of SB-12 (0.4 mmol) and stirred vigorously for 0.5 h, which was recorded as solution A. 1.6 g (12.8 mmol) of melamine and 0.536 g of 2,4-diaminobenzenesulfonic acid (2.8 mmol) were completely dissolved in 240 mL of deionized water as solution B. After mixing and stirring the AB solutions for 1 h, 12 mL of formaldehyde was added, and the mixture was centrifuged, washed with water, and dried after reacting for 120 min. The obtained yellow solid was placed in a tubular furnace and carbonized at 600 °C for 120 min under a nitrogen atmosphere to obtain a supercapacitor electrode material of sulfur-nitrogen co-doped hollow carbon nanorings. Its electrochemical properties under a three-electrode system are as follows: Fig.11 shown. Example 12

[0050] At room temperature, 0.173 g (0.4 mmol) of AOT was completely dissolved in 40 mL of deionized water with 0.135 g of SB-12 (0.4 mmol) and stirred vigorously for 0.5 h, which was recorded as solution A. 1.6 g (12.8 mmol) of melamine and 0.536 g of 2,4-diaminobenzenesulfonic acid (2.8 mmol) were completely dissolved in 240 mL of deionized water as solution B. After mixing and stirring the AB solutions for 1 h, 12 mL of formaldehyde was added, and the mixture was centrifuged, washed with water, and dried after reacting for 120 min. The obtained yellow solid was placed in a tubular furnace and carbonized at 700 ° C for 120 min under a nitrogen atmosphere to obtain a supercapacitor electrode material of sulfur-nitrogen co-doped hollow carbon nanorings. Its electrochemical properties under a three-electrode system are as follows: Fig.12 shown. Embodiment 13

[0051] At room temperature, 0.173 g (0.4 mmol) of AOT was completely dissolved in 40 mL of deionized water with 0.135 g of SB-12 (0.4 mmol) and stirred vigorously for 0.5 h, which was recorded as solution A. 1.6 g (12.8 mmol) of melamine and 0.536 g of 2,4-diaminobenzenesulfonic acid (2.8 mmol) were completely dissolved in 240 mL of deionized water as solution B. After mixing and stirring the AB solutions for 1 h, 12 mL of formaldehyde was added, and the mixture was centrifuged, washed with water, and dried after reacting for 120 min. The obtained yellow solid was placed in a tubular furnace and carbonized at 800 °C for 120 min under a nitrogen atmosphere to obtain a supercapacitor electrode material of sulfur-nitrogen co-doped hollow carbon nanorings. Its electrochemical properties under a three-electrode system are as follows: Fig.13 By comparing Examples 11, 12, and 13, it is found that the electrochemical performance of the carbonization at 700°C is the best, because too low a carbonization temperature will lead to poor conductivity of the material, and too high a carbonization temperature may cause the material structure to collapse. Embodiment 14

[0052] The material obtained in Example 9 was subjected to 5000 charge-discharge cycle tests in a three-electrode system. -1 The cycling performance at current density is Fig.14 shown. Embodiment 15

[0053] Nitrogen adsorption / desorption tests were performed on Examples 11, 2, and 13. Fig.15 As shown, all isotherms are type I / IV, that is, micropores and mesopores exist at the same time, which belongs to a multi-level porous material. As the carbonization temperature increases, the specific surface area of ​​the material increases, and the pore structure also increases, which is conducive to the transmission of electrons. Example 16

[0054] The pore size test was performed on Examples 11, 12, and 13, and the data are shown in Table 1.

[0055] Table 1 Pore diameter data of synthetic materials of Examples 11, 12 and 13

[0056] a Micropore specific surface area obtained using the T-Plot method.

[0057] b The total pore volume was obtained at P / P0≈0.99.

[0058] c Micropore volume obtained using the T-Plot method.

[0059] d Pore ​​diameter calculated using the HK method.

[0060] It can be seen that with the increase of carbonization temperature, the specific surface area and pore volume of sulfur-nitrogen co-doped carbon nanorings increase. Embodiment 17

[0061] The elemental composition analysis test was performed on Examples 11, 12, and 13, and the data are shown in Table 2.

[0062] Table 2 Elemental composition of synthetic materials of Examples 11, 12 and 13

[0063] It can be seen that sulfur-nitrogen co-doped hollow carbon nanorings exhibit the best heteroatom doping effect when carbonized at 700 °C.

[0064] For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing sulfur-nitrogen co-doped hollow carbon nanorings, characterized in that: The following steps are involved: (1) stirring and mixing anionic surfactant and amphoteric surfactant in an aqueous phase; (2) adding melamine and aromatic amine-acid into water and dissolving them uniformly; the amount of aromatic amine-acid used is 5% to 40% of the molar amount of melamine; (3) mixing the solutions of step (1) and step (2), and continuing to stir to construct a composite micelle system; the amount of surfactant used is 1% to 10% of the molar amount of melamine; (4) Add formaldehyde, react for 10-120 min, and centrifuge to obtain a solid; (5) Sulfur-nitrogen co-doped hollow carbon nanorings were obtained by calcination under an inert atmosphere.

2. The method for preparing a sulfur-nitrogen co-doped hollow carbon nanoring according to claim 1, characterized in that: The aromatic amine-acid is one of 2,4-diaminobenzenesulfonic acid, 2,5-diaminobenzenesulfonic acid, 3,5-diaminobenzenesulfonic acid, o-aminobenzenesulfonic acid, m-aminobenzenesulfonic acid, p-aminobenzenesulfonic acid and m-phenylenediamine disulfonic acid.

3. The method for preparing a sulfur-nitrogen co-doped hollow carbon nanoring according to claim 1, characterized in that: The anionic surfactant is one of sodium bis(2-ethylhexyl)sulfosuccinate, sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.

4. The method for preparing a sulfur-nitrogen co-doped hollow carbon nanoring according to claim 1, characterized in that: The zwitterionic surfactant is one of cocamidopropyl betaine, dodecyl dimethyl betaine and 3-sulfopropyl dodecyl dimethyl betaine.

5. The method for preparing a sulfur-nitrogen co-doped hollow carbon nanoring according to claim 1, characterized in that: The molar ratio of the anionic surfactant and the amphoteric surfactant when compounded is 1:

1.

6. The method for preparing a sulfur-nitrogen co-doped hollow carbon nanoring according to claim 5, characterized in that: The amount of the anionic surfactant and the amphoteric surfactant is greater than 0 and less than the critical micelle concentration.

7. The method for preparing a sulfur-nitrogen co-doped hollow carbon nanoring according to claim 1, characterized in that: The gas used in the inert atmosphere is nitrogen or argon, the carbonization temperature is 600-800°C, and the time is 80-120 min.

8. A sulfur-nitrogen co-doped hollow carbon nanoring, characterized in that: The method is prepared by any one of claims 1 to 7.

9. The sulfur-nitrogen co-doped hollow carbon nanoring according to claim 8, characterized in that: The size of the nanoring is 3-5 µm.

10. The sulfur-nitrogen co-doped hollow carbon nanoring according to claim 8, characterized in that: The hollow carbon nanoring has a nitrogen content of 7% to 20% and a sulfur content of 1.2% to 3%.

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