N-doped carbon nanosphere self-supporting material growing on carbon cloth in situ as well as preparation and application of N-doped carbon nanosphere self-supporting material

Abstract

The invention relates to an N-doped carbon nanosphere self-supporting material growing on carbon cloth in situ and preparation and application thereof.The preparation process of the self-supporting material comprises the steps that S1, zinc salt, nickel salt and dimethylimidazole are dissolved in an alcohol solvent, the mixture is transferred into a reaction kettle after being evenly dispersed, then a carbon-based substrate is immersed into the reaction kettle, heating is conducted for a first time for reaction, and a reaction product is obtained; taking out, washing and drying; s2, immersing the material obtained in S1 into an alcoholic solution containing ruthenium salt, heating for secondary reaction, taking out, washing and drying to obtain a self-supporting material A; and S3, performing high-temperature heat treatment on the self-supporting material A in a protective atmosphere to obtain an N-doped carbon nanosphere self-supporting material B, namely a target product. Compared with the prior art, the self-supporting material disclosed by the invention has excellent HER (Hydrogen Evolution Reaction) dynamic performance and good stability, and has a good application prospect in the fields of hydrogen production by electrolysis of water and new energy storage materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage materials and electrocatalysis, and relates to a self-supporting material of N-doped carbon nanospheres grown in-situ on carbon cloth, and its preparation and application. Background Art

[0002] Hydrogen energy has many advantages such as zero emissions, high energy density, and renewability. In the future, it will surely play an important role in promoting the adjustment of industrial structure and energy structure. Among them, water electrolysis for hydrogen production is one of the most effective ways to obtain hydrogen. However, the process of water electrolysis for hydrogen production involves kinetic problems and stability problems, which hinder its further development. Therefore, the catalyst plays a key role in the process of water electrolysis.

[0003] At present, among noble metals, Pt, Rh, and Ir have good activity, but their high prices and poor stability limit their further development. To solve the above problems, Ru, which has catalytic activity and electron orbit similar to Pt and is inexpensive, has good application prospects. In actual applications, Ru metal is prone to agglomeration or dissolution in strong acid electrolytes, greatly affecting catalytic activity and stability. In the prior art, Ru metal is loaded onto two-dimensional materials such as oxides and sulfides, and the synthesized ruthenium metal particles are large in size and prone to agglomeration, restricting their utilization rate and catalytic activity. For example, the self-supporting electrode and its preparation method and application disclosed in CN202411246445.8 include a conductive substrate, nitrogen-doped carbon nanotubes, and FeNi3 particles distributed inside the nanotubes; the nitrogen-doped carbon nanotubes grow on the surface of the conductive substrate. Compared with the present invention, the existing self-supporting electrode materials have the following performance defects or deficiencies in the application of water electrolysis for hydrogen production (HER / OER): 1. Insufficient intrinsic active sites: The surface active site density of traditional materials (such as Co3O4 supported on nickel foam) is low, and the edge / defect sites are not fully exposed, resulting in limited current density; 2. Defects in stability and durability: In acidic electrolytes, metal-based substrates (such as copper foam and nickel foam) are easily corroded, resulting in the peeling off of the active layer; 3. Delayed bubble release: The bubble adhesion force of traditional two-dimensional planes or disordered porous structures is strong, and bubbles accumulate and block active sites, increasing the polarization resistance, etc. All in all, the core problems of existing self-supporting electrodes in water electrolysis for hydrogen production focus on high overpotential, poor stability, and durability defects. Summary of the Invention

[0004] The purpose of the present invention is to provide a self-supporting material of N-doped carbon nanospheres grown in-situ on carbon cloth, and its preparation and application. In the obtained self-supporting material Ru@Ni / Zn-NC, small-sized carbon nanospheres are uniformly dispersed on the surface of carbon fibers, which can effectively inhibit the agglomeration of the material and improve the performance of the material. When applied subsequently, the self-supporting material can be directly used as an electrode material without adding any binder, effectively ensuring electron conduction and transportation, etc.

[0005] The object of the present invention can be achieved by the following technical solutions:

[0006] In one aspect, the present invention provides a preparation method of a self-supporting material of N-doped carbon nanospheres grown in-situ on carbon cloth. First, Ni / Zn-MOF is grown in-situ on carbon cloth by solvothermal method, and ruthenium metal is anchored on the inner and outer surfaces of Ni / Zn-MOF through host-guest interaction by secondary solvothermal method. Then, high-temperature calcination is carried out under an argon protection atmosphere to evaporate a large amount of Zn, and the remaining part of Ru, Zn and Ni is reconstructed to prepare a self-supporting material of N-doped carbon nanospheres.

[0007] Specifically, it includes the following steps:

[0008] S1. Dissolve zinc salt, nickel salt and dimethylimidazole in an alcohol solvent, transfer it to a reaction kettle after uniform dispersion, then immerse the carbon-based substrate in it, heat for the first reaction, take out, wash and dry;

[0009] S2. Immerse the material obtained in S1 in an alcohol solution containing ruthenium salt, heat for the second reaction, take out, wash and dry to obtain a self-supporting material A;

[0010] S3. Carry out high-temperature heat treatment on the self-supporting material A under a protective atmosphere to obtain a self-supporting material B of N-doped carbon nanospheres, which is the target product.

[0011] Further, the zinc salt is zinc acetate, the nickel salt is nickel chloride, and the ruthenium salt is ruthenium chloride.

[0012] Further, in S1, the addition ratio of zinc salt, nickel salt, dimethylimidazole and alcohol solvent is (0.8 - 1.2) mmol: 0.1 mmol: (2.5 - 3.5) mmol: (20 - 40) mL.

[0013] Further, in S1, the temperature of the first reaction is 50 - 70 °C, preferably 60 °C, and the time is 6 - 8 h.

[0014] Further, in S1 and S2, the drying process is vacuum drying at 60 °C for 10 - 20 h.

[0015] Further, the carbon-based substrate is carbon cloth, and the alcohol solvent is one or a mixture of two of methanol and ethanol.

[0016] Further, in S2, the ratio of ruthenium salt to nickel salt required for preparing the material obtained in S1 is (4 - 6) mg: 0.1 mmol.

[0017] Further, in S2, the temperature of the second reaction is 50 - 70 °C, and the time is 2 - 4 h.

[0018] Further, in S3, the protective atmosphere is an inert atmosphere such as argon; the temperature of the high-temperature heat treatment is 550-650 °C, preferably 600 °C, and the time is 1-3 h, preferably 2 h.

[0019] On the other hand, the present invention provides a self-supporting material of N-doped carbon nanospheres, which is prepared by the preparation method described in the first aspect above. In the obtained self-supporting material of Ru@Ni / Zn-NC with N-doped carbon nanospheres, small-sized carbon nanospheres are uniformly dispersed on the surface of carbon fibers.

[0020] In the third aspect, the present invention also provides an application of a self-supporting material of N-doped carbon nanospheres as an electrode in acidic electrolytic water hydrogen production.

[0021] Compared with the prior art, the present invention adopts an in-situ preparation method to directly grow Ni / Zn-MOF on the surface of carbon cloth fibers. The secondary solvothermal method promotes ruthenium ions to enter the inner and outer surfaces of Ni / Zn-MOF, and on the other hand, it is beneficial to strengthen the host-guest interaction force between ruthenium ions and Ni / Zn-MOF. Secondly, through the high-temperature carbonization heat treatment process, most of the zinc ions evaporate, and the confinement effect produces a uniformly dispersed Ru@Ni / Zn-NC self-supporting material. Moreover, the precursor metal-organic framework provides a large specific surface area and a stable framework, and the prepared material presents a nanosphere structure. Due to the acquisition of such small-sized nanospheres, the catalytic performance of the material in acidic electrolytic water hydrogen production is further improved. The in-situ grown self-supporting material of the present invention can be directly used as an electrode without using a binder, enhancing the overall conductivity of the material. Description of the Drawings

[0022] Figure 1 FIG. 16 is an SEM image of Ru@Ni / Zn-MOF prepared after hydrothermal treatment in Example 1.

[0023] Figure 2 FIG. 20 is an SEM image of Ru@Ni / Zn-NC prepared after heat treatment in Example 1.

[0024] Figure 3 FIG. 24 is an SEM image of Ru@Ni / Zn-NC-1 prepared after electrolysis in Example 1.

[0025] Figure 4 FIG. 28 is an XRD pattern of Example 1 and CC.

[0026] Figure 5 FIG. 32 is a comparison chart of polarization curves of Ru@Ni / Zn-NC in Example 1 and Ru@Ni / Zn-MOF, Ni1 / Zn-MOF and Ru-NC in Comparative Examples 1-5 respectively.

[0027] Figure 6Figure 2 is the chronoamperometry diagram of Ru@Ni / Zn-NC in Example 1. Detailed implementation mode

[0028] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and gives detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following embodiments.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application herein are only for the purpose of describing specific embodiments, and are not intended to limit this application.

[0030] As used herein, the alternative ranges of the terms "and / or", "or / and", "and / or" include any one of two or more related listed items, and also include any and all combinations of the related listed items. The said any and all combinations include any two related listed items, any more related listed items, or the combination of all related listed items. It should be noted that when at least two conjunctions selected from "and / or", "or / and", "and / or" are used to connect at least three items, it should be understood that in this application, this technical solution undoubtedly includes the technical solution connected by "logical AND", and also undoubtedly includes the technical solution connected by "logical OR".

[0031] In this application, among the technical features described in an open-ended manner, there are included closed technical solutions composed of the listed features, as well as open technical solutions including the listed features.

[0032] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous, and include the minimum and maximum values of this range, as well as each value between such minimum and maximum values. Further, when the range refers to an integer, it includes each integer between the minimum and maximum values of this range. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0033] Only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recorded; and any lower limit can be combined with other lower limits to form a range not explicitly recorded. Similarly, any upper limit can be combined with any other upper limit to form a range not explicitly recorded. In addition, each individually disclosed point or single numerical value itself can be used as a lower limit or an upper limit to be combined with any other point or single numerical value or with other lower limits or upper limits to form a range not explicitly recorded.

[0034] In the present application, unless otherwise specified, the temperature parameter allows both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, ±1°C are allowed.

[0035] In this article, the "suitable combination method", "suitable method", "any suitable method", etc., the "suitable" described therein is subject to being able to implement the technical solution of the present application, solve the technical problems of the present application, and achieve the expected technical effects of the present application.

[0036] In the present application, "further", "even further", "especially", etc. are used for descriptive purposes, indicating differences in content, but should not be construed as limiting the protection scope of the present application.

[0037] In the present application, "optionally", "optional", "option", mean that it can be either present or absent, that is, it refers to any one of the two alternative options of "present" or "absent". If "optional" appears multiple times in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" is independent.

[0038] In the description of the application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0039] Unless otherwise specified, all preparations and tests in this article are carried out in an environment of 25°C.

[0040] In this article, "including", "containing", "including", "containing", "having" or other variants are intended to cover non-closed inclusion, and no distinction is made between these terms. The term "containing" means that other steps and components can be added without affecting the final result. The compositions and methods / processes of the present invention contain, consist of, and consist essentially of the necessary elements and limitations described herein and any additional or optional components, ingredients, steps, or limitations described herein. In this article, no distinction is made between the terms "efficacy", "performance", "effect", "efficiency".

[0041] If there is no special instruction, all implementation manners and optional implementation manners of the present application can be combined with each other to form a new technical solution. If there is no special instruction, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0042] If there is no special instruction, all steps of the present application can be carried out sequentially or randomly, and preferably sequentially.

[0043] Example 1:

[0044] The self - supported material Ru@Ni / Zn - NC of N - doped carbon nanospheres is prepared by growing and deriving Ni / Zn - MOF on carbon cloth, including the following steps:

[0045] S1: Cut the carbon cloth substrate to a size of 2 cm×2 cm, ultrasonically clean it with ethanol and deionized water for 30 min respectively, and vacuum dry it after cleaning.

[0046] S2: Weigh 1 mmol of Zn(CHCOO)2·2H2O, 0.1 mmol of NiCl2·6H2O, and 3 mmol of 2 - methylimidazole, dissolve them in 30 mL of methanol, and stir evenly for 30 minutes.

[0047] S3: Transfer the mixed solution to a 100 - mL reaction kettle, then place the clean carbon cloth in it, and heat it at 60 °C for 6 h. After cooling, take out the sample (i.e., the carbon cloth loaded with Ni / Zn - MOF).

[0048] S4: Wash the sample three times with ethanol and pure distilled water, and dry it in a vacuum drying oven at 60 °C for 12 h.

[0049] S5: Weigh 5 mg of RuCl3, dissolve it in 30 mL of methanol, and stir evenly for 30 minutes.

[0050] S6: Transfer it to a 100 - mL reaction kettle, then place the carbon cloth loaded with Ni / Zn - MOF in it, and heat it at 60 °C for 3 h.

[0051] S7: After cooling, take out the sample, wash it three times with pure distilled water, and dry it in a vacuum drying oven at 60 °C for 12 h.

[0052] S8: Place the carbon cloth loaded with Ni / Zn - MOF into a tube furnace, in flowing Ar, heat it at a heating rate of 5 °C / min to 600 °C for heat preservation and calcination for 2 h. After experiencing calcination at 600 °C, most of the Zn is evaporated and decomposed, forming vacancy sites. Naturally cool to room temperature to obtain the self - supported material of N - doped carbon nanospheres, denoted as Ru@Ni / Zn - NC.

[0053] Comparative Example 1

[0054] S1: Ultrasonically clean the carbon cloth substrate with ethanol and deionized water for 30 min respectively, and vacuum dry it after cleaning.

[0055] S2: Weigh 1 mmol of Zn(CHCOO)2·2H2O, 0.1 mmol of NiCl2·6H2O, and 3 mmol of 2 - methylimidazole, dissolve them in 30 mL of methanol, and stir evenly for 30 minutes.

[0056] S3: Transfer the mixed solution into a 100 mL reactor, then place the clean carbon cloth in it, heat at 60 °C for 6 h, take out the sample after cooling, and label it as Ni / Zn-MOF.

[0057] Comparative Example 2

[0058] S1: Ultrasonically clean the carbon cloth substrate with ethanol and deionized water for 30 min respectively, and then dry it in vacuum after cleaning.

[0059] S2: Weigh 1 mmol of Zn(CHCOO)2·2H2O, 1 mmol of Ni(NO3)2·6H2O, and 3 mmol of 2-methylimidazole, dissolve them in 30 mL of methanol, and stir evenly for 30 minutes.

[0060] S3: Transfer the mixed solution into a 100 mL reactor, then place the clean carbon cloth in it, heat at 60 °C for 6 h, and take out the sample after cooling.

[0061] S4: Wash the sample three times with ethanol and pure distilled water, and dry it in a vacuum drying oven at 60 °C for 12 h.

[0062] S5: Weigh 5 mg of RuCl3, dissolve it in 30 mL of methanol, and stir evenly for 30 minutes.

[0063] S6: Transfer it into a 100 mL reactor, then place the carbon cloth loaded with Ni / Zn-MOF in it, and heat at 60 °C for 3 h.

[0064] S7: Cool and take out the sample, wash it three times with pure distilled water, and dry it in a vacuum drying oven at 60 °C for 12 h.

[0065] S8: Place the carbon cloth loaded with Ni / Zn-MOF into a tubular furnace, heat it to 600 °C at a heating rate of 5 °C / min in flowing Ar for heat preservation and calcination for 2 h. After calcination at 600 °C, most of the Zn is evaporated and decomposed to form vacancy sites. Naturally cool to room temperature to obtain the N-doped carbon nanosphere self-supporting material, labeled as Ru@Ni1 / Zn-NC.

[0066] Comparative Example 3

[0067] S1: Weigh 1 mmol of Zn(CHCOO)2·2H2O, 0.4 mmol of NiCl2·6H2O, and 3 mmol of 2-methylimidazole, dissolve them in 50 mL of methanol, and stir evenly for 30 minutes.

[0068] S2: Transfer it into a 100 mL reactor, then place the clean carbon cloth in it, heat at 60 °C for 24 h, and take out the sample after cooling.

[0069] S3: Wash it three times with ethanol and pure distilled water, and dry it in a vacuum drying oven at 60 °C for 12 h to obtain an intermediate on the carbon cloth;

[0070] S4: Weigh 5 mg of RuCl3 and dissolve it in 30 mL of methanol, and stir it evenly for 30 minutes

[0071] S5: Transfer the sample to a 100 mL reaction kettle, then place the carbon cloth loaded with Ni1 / Zn-MOF in it, and heat it at 60 °C for 6 h;

[0072] S6: Take out the sample after cooling, wash it three times with ethanol and pure distilled water, and dry it in a vacuum drying oven at 60 °C for 12 h;

[0073] S7: Place the carbon cloth loaded with Ni1 / Zn-MOF in a tubular furnace, and under flowing argon, heat it at a heating rate of 5 °C / min to 600 °C for heat preservation and calcination for 2 h, and naturally cool it to room temperature to obtain the N-doped carbon nanosphere self-supporting material denoted as Ru@Ni1 / Zn-NC.

[0074] Comparative Example 4

[0075] S1: Weigh 5 mg of RuCl3 and dissolve it in 30 mL of methanol, and stir it evenly for 30 minutes;

[0076] S2: Then transfer it to a 100 mL reaction kettle, then place the clean carbon cloth in it, and heat it at 60 °C for 6 h, and take out the sample after cooling;

[0077] S3: Wash the sample three times with ethanol and pure distilled water, and dry it in a vacuum drying oven at 60 °C for 12 h;

[0078] S4: Place the load in a tubular furnace, and under flowing argon, heat it at a heating rate of 5 °C / min to 600 °C for heat preservation and calcination for 2 h, and naturally cool it to room temperature to obtain a sample denoted as Ru-NC.

[0079] Comparative Example 5

[0080] S1: Weigh 1 mmol of Zn(CHCOO)2·2H2O, 1.5 mmol of NiCl2·6H2O, and 1.5 mmol of 2-methylimidazole and dissolve them in 30 mL of methanol, and stir it evenly for 30 minutes;

[0081] S2: Transfer the mixed solution to a 100 mL reaction kettle, then place the clean carbon cloth in it, and heat it at 60 °C for 6 h, and take out the sample after cooling;

[0082] S3: Wash the sample three times with ethanol and pure distilled water, and dry it in a vacuum drying oven at 60 °C for 12 h;

[0083] S4: Weigh 5 mg of RuCl3 and dissolve it in 30 mL of methanol, and stir evenly for 30 minutes;

[0084] S5: Transfer it to a 100 mL reaction kettle, then place the carbon cloth loaded with Ni / Zn-MOF in it, and heat it at 60 °C for 3 h;

[0085] S7: Take out the sample after cooling, wash it three times with pure distilled water, and dry it in a vacuum drying oven at 60 °C for 12 h;

[0086] S8: Put the carbon cloth loaded with Ni / Zn-MOF into a tube furnace, and under flowing Ar, heat it at a heating rate of 5 °C / min to 600 °C for heat preservation calcination for 2 h. After calcination at 600 °C, most of the Zn is evaporated and decomposed to form vacant sites. Naturally cool to room temperature to obtain the self-supporting material of N-doped carbon nanospheres, denoted as Ru@Ni / Zn-NC-2.

[0087] Comparative Example 6

[0088] S1: Weigh 1 mmol of NiCl2·6H2O and 1.5 mmol of 2-methylimidazole and dissolve them in 30 mL of methanol, and stir evenly for 30 minutes;

[0089] S2: Transfer the mixed solution to a 100 mL reaction kettle, then place the clean carbon cloth in it, and heat it at 60 °C for 6 h. Take out the sample after cooling;

[0090] S3: Wash the sample three times with ethanol and pure distilled water, and dry it in a vacuum drying oven at 60 °C for 12 h;

[0091] S4: Weigh 5 mg of RuCl3 and dissolve it in 30 mL of methanol, and stir evenly for 30 minutes;

[0092] S5: Transfer it to a 100 mL reaction kettle, then place the carbon cloth loaded with Ni / Zn-MOF in it, and heat it at 60 °C for 3 h;

[0093] S7: Take out the sample after cooling, wash it three times with pure distilled water, and dry it in a vacuum drying oven at 60 °C for 12 h;

[0094] S8: Put the carbon cloth loaded with Ni / Zn-MOF into a tube furnace, and under flowing Ar, heat it at a heating rate of 5 °C / min to 600 °C for heat preservation calcination for 2 h. After calcination at 600 °C, most of the Zn is evaporated and decomposed to form vacant sites. Naturally cool to room temperature to obtain the self-supporting material of N-doped carbon nanospheres, denoted as Ru@Ni-NC.

[0095] Comparative Example 7

[0096] S1: Cut the carbon cloth substrate to a size of 2 cm × 2 cm, ultrasonically clean it with ethanol and deionized water for 30 min respectively, and then dry it in vacuum after cleaning;

[0097] S2: Weigh 1 mmol Zn(CHCOO)2·2H2O, 0.1 mmol NiCl2·6H2O, and 3 mmol 2-methylimidazole, dissolve them in 30 mL of methanol, and stir evenly for 30 minutes;

[0098] S3: Transfer the mixed solution to a 100 mL reaction kettle, then place the clean carbon cloth in it, and heat it at 60 °C for 6 h. After cooling, take out the sample (i.e., the carbon cloth loaded with Ni / Zn-MOF);

[0099] S4: Wash the sample three times with ethanol and pure distilled water, and dry it in a vacuum drying oven at 60 °C for 12 h;

[0100] S5: Take out the sample after cooling, wash it three times with pure distilled water, and dry it in a vacuum drying oven at 60 °C for 12 h;

[0101] S6: Place the carbon cloth loaded with Ni / Zn-MOF in a tubular furnace, and heat it to 600 °C at a heating rate of 5 °C / min in flowing Ar for heat preservation and calcination for 2 h. After calcination at 600 °C, the sample is denoted as Ni / Zn-NC.

[0102] The obtained nanofibers of the iron single-atom catalyst coupled with the defective carbon support were characterized by scanning electron microscopy (SEM).

[0103] Figure 1 SEM image of Ru@Ni / Zn-MOF grown in-situ on carbon cloth for Comparative Example 1. It can be seen from the figure that regular polyhedral structures are evenly dispersed on the surface of carbon cloth fibers.

[0104] Figure 2 SEM image of the self-supporting material Ru@Ni / Zn-NC with N-doped carbon nanospheres grown in-situ on carbon cloth prepared in Example 1. It can be seen from the figure that ultra-small sized nanospheres are evenly loaded on the surface of carbon cloth fibers.

[0105] Figure 3 SEM image of Ru@Ni / Zn-NC-1 prepared in-situ on carbon cloth for Comparative Example 2. It can be seen from the figure that after long-term electrolysis, small-sized nanospheres still remain evenly loaded on the surface of carbon cloth fibers, further indicating that the prepared Ru@Ni / Zn-NC maintains stability during long-term electrolysis under strong acid conditions.

[0106] Figure 4 The XRD results in show that after high-temperature heat treatment in Example 1, it can be clearly observed that Ru is confirmed x / Zn,Ni-NC@CC has two broad diffraction peaks at 25° and 44°. Ru does not agglomerate, and no Zn,Ni alloy phase is detected, indicating that Zn and Ni are likely to exist in the form of atomic dispersion.

[0107] Electrochemical performance test

[0108] An electrochemical workstation was used to evaluate the electrochemical performance of the self-supported materials of Example 1 and Comparative Examples 1-4. The three-electrode system consisted of a counter electrode (carbon rod), a reference electrode (reference electrode), and a working electrode (prepared electrode, area 1×1 cm -2 ). The test electrolyte was 0.5 M H2SO4, and the scan rate for the linear cyclic voltammogram (LSV) measurement was 5 mV / s.

[0109] Table 1 shows the overpotentials for hydrogen production of Example 1 and Comparative Examples 1-6 under 0.5 M H2SO4 electrolysis

[0110]

[0111] Table 1 and Figure 5 The results show that Ru@Ni / Zn-NC synthesized on carbon cloth has the smallest overpotential under the same conditions, with overpotentials of 173.3 mV and 215.3 mV at 10 mA.cm -2 and 100 mA.cm -2 respectively. Compared with others, it shows that Ru@Ni / Zn-NC has good electrochemical activity as a self-supported material. Similarly Figure 6 For Ru@Ni / Zn-NC obtained on carbon cloth in Example 1, it is the chronoamperometry test chart in 0.5 M H2SO4 solution. The results show that the prepared Ru@Ni / Zn-NC self-supported material can still maintain high stability after 24 hours of long-term electrolysis test.

[0112] In Example 1, Ru serves as an efficient catalytic center, and the dual-metal doping of Ni and Zn forms a synergistic effect, optimizing the electronic structure and reducing the energy barrier of HER. The nitrogen-doped carbon (NC) support further enhances the electron conductivity and the dispersion of active sites. In contrast, the lack of a similar structure in the comparative examples leads to a reduction in active sites and a decline in catalytic efficiency. For example, in Comparative Examples 2, 3, 5, etc., as the content of Ni metal increases, the catalytic activity decreases significantly. It may be that Ni enhances the adsorption of intermediates and slows down the generation of H2. In Comparative Example 7, without adding Ru, its overpotential increases significantly. Comparative Example 4 may be a single metal, only Ru / NC, lacking the interfacial synergistic effect of the core-shell structure, resulting in insufficient exposure of active sites and slower reaction kinetics. Using carbon cloth as a self-supporting carrier avoids the use of adhesives and improves the material conductivity and mechanical stability. The high specific surface area and defective structure of nitrogen-doped carbon (NC) promote the anchoring and mass transfer of active substances. The formation of a core-shell structure through controllable synthesis effectively prevents the agglomeration of active components and exposes more active sites. The uniform loading of carbon cloth further optimizes the three-phase interface reaction.

[0113] The present invention uses an in-situ preparation method to stepwise synthesize a self-supporting material Ru@Ni / Zn-NC on carbon cloth. First, a polyhedral MOF is in-situ grown on the carbon cloth through coordination self-assembly. The ruthenium ions enter the inner and outer surfaces of the MOF in the form of host-guest through a secondary hydrothermal method. Then, high-temperature pyrolysis treatment is carried out to evaporate a large amount of zinc ions to form vacancies, enabling Ru to bind more tightly to the carbon nanospheres. Among them, the small-sized carbon nanospheres are uniformly dispersed on the surface of carbon fibers, which can effectively inhibit the agglomeration of materials and improve the performance of the materials. The self-supporting material synthesized in-situ in the present invention can be directly used as an electrode material without adding any adhesives, effectively ensuring electron conduction and transportation.

[0114] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. Those skilled in the art can obviously make various modifications to these embodiments easily and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A preparation method of an N-doped carbon nanosphere self-supporting material grown in-situ on carbon cloth, characterized in that, It includes the following steps: S1. Dissolve zinc salt, nickel salt and dimethylimidazole in an alcohol solvent, transfer it to a reaction kettle after uniform dispersion, then immerse the carbon-based substrate into it, heat for the first reaction, take it out, wash and dry; S2. Immerse the material obtained in S1 into an alcohol solution containing ruthenium salt, heat for the second reaction, take it out, wash and dry to obtain the self-supporting material A; S3. Perform high-temperature heat treatment on the self-supporting material A under a protective atmosphere to obtain the N-doped carbon nanosphere self-supporting material B, which is the target product.

2. The preparation method of an N-doped carbon nanosphere self-supporting material in-situ grown on carbon cloth according to claim 1, wherein, The zinc salt is zinc acetate, the nickel salt is nickel chloride, and the ruthenium salt is ruthenium chloride.

3. The preparation method of a self-supported N-doped carbon nanosphere material grown in-situ on carbon cloth according to claim 1, characterized in that, In S1, the addition ratio of zinc salt, nickel salt, dimethylimidazole and alcohol solvent is (0.8 - 1.2) mmol: 0.1 mmol: (2.5 - 3.5) mmol: (20 - 40) mL.

4. The preparation method of a self-supporting material of N-doped carbon nanospheres in-situ grown on carbon cloth according to claim 1, characterized in that, In S1, the temperature of the first reaction is 50 - 70 °C and the time is 6 - 8 h.

5. The preparation method of an N-doped carbon nanosphere self-supporting material in-situ grown on carbon cloth according to claim 1, characterized in that, The carbon-based substrate is carbon cloth, and the alcohol solvent is one or a mixture of two of methanol and ethanol.

6. The preparation method of an N-doped carbon nanosphere self-supporting material in-situ grown on carbon cloth according to claim 1, characterized in that, In S2, the ratio of ruthenium salt to nickel salt required for preparing the material obtained in S1 is (4 - 6) mg: 0.1 mmol.

7. The preparation method of an N-doped carbon nanosphere self-supporting material in-situ grown on carbon cloth according to claim 1, characterized in that, In S2, the temperature of the second reaction is 50 - 70 °C and the time is 2 - 4 h.

8. The preparation method of a self-supporting material of N-doped carbon nanospheres in-situ grown on carbon cloth according to claim 1, characterized in that, In S3, the protective atmosphere is argon; the temperature of the high-temperature heat treatment is 550 - 650 °C and the time is 1 - 3 h.

9. An N-doped carbon nanosphere self-supporting material, which is prepared by the preparation method according to any one of claims 1 - 8.

10. Application of an N-doped carbon nanosphere self-supporting material according to claim 9 as an electrode in acidic electrolytic water hydrogen production.

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