Preparation method of carbon dot doped fe-ni3s2@nf electrocatalyst and application to hydrogen production by decomposing urea
By loading carbon dots onto Fe-Ni3S2 nanosheets to form a unique nanosheet structure, the kinetics of the urea oxidation reaction are solved, the catalytic performance of the electrocatalyst is improved, and efficient urea decomposition and environmental purification are achieved, making it suitable for urea fuel cells.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGSU UNIV
- Filing Date
- 2023-03-20
- Publication Date
- 2026-05-12
AI Technical Summary
In the prior art, the urea oxidation reaction (UOR) is a complex six-electron transfer process with slow kinetics, which limits the catalytic performance. Furthermore, the regulatory effect of carbon materials on nanocomposite materials has not been fully utilized, resulting in low efficiency of electrocatalysts in decomposing urea to produce hydrogen.
A carbon dot-doped Fe-Ni3S2@NF electrocatalyst was adopted. By loading 2D Fe-Ni3S2 nanosheets onto nickel foam and combining them with 0D carbon dots, a unique nanosheet structure was formed, which enhanced the specific surface area and reaction sites of the electrocatalyst and promoted the adsorption, decomposition and charge transfer of urea.
This method improves the efficiency of electrocatalysts in decomposing urea to produce hydrogen, reduces reaction energy consumption, achieves high-efficiency electrocatalytic performance, and solves the problem of urea pollution in the environment. It is suitable for the application of high-efficiency catalysts in urea fuel cells.
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Figure CN116463670B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nanocomposite materials technology, and relates to electrocatalysts, particularly to a method for preparing a carbon dot-doped Fe-Ni3S2@NF electrocatalyst and its application in the electrocatalytic decomposition of urea to produce hydrogen. Background Technology
[0002] Hydrogen energy, as a clean and renewable energy source, has attracted widespread attention due to its green and pollution-free advantages in addressing energy and environmental issues. Electrolysis of water to produce hydrogen is considered a simple, convenient, and promising new energy technology. However, the oxygen evolution reaction (OER), as a half-reaction at the anode in a water electrolysis system, is affected by 4e⁻. - The transfer process involves a considerably high overpotential, which significantly limits the energy efficiency of hydrogen production. Theoretically, replacing the slow oxygen evolution reaction (OER) with other thermodynamically favorable small-molecule electro-oxidation reactions could significantly improve H2 production efficiency. Currently, urea electro-oxidation is considered a promising anodic reaction for H2 production, with a theoretical voltage of 0.37V (relative to the reversible hydrogen electrode (vs. RHE)), which is better than the traditional OER (1.23V vs. RHE). Furthermore, urea electrolysis can not only lower the potential required for H2 production but also purify urea-rich wastewater. The urea oxidation reaction is also crucial in urea fuel cells; reducing the overpotential during the reaction can greatly improve the efficiency of urea fuel cells.
[0003] However, the anodic oxidation reaction of urea (UOR)(CO(NH2)2+6OH) - = N2 + 5H2O + CO2 + 6e - Urea oxidation is a complex six-electron transfer process, and its slow kinetics limit its catalytic performance. Therefore, to improve the catalytic performance of urea oxidation catalysts, researchers have continuously strived to design various types of nanocomposite materials. These mainly include vacancy introduction, atomic doping, and the construction of heterostructures. Among these, Fe atomic doping can alter the coordination environment of Ni in Ni3S2, optimize the binding strength of intermediates in the urea oxidation reaction at the Ni3S2 active sites, accelerate electron transport, improve conductivity, expose more active sites, and promote reaction kinetics. However, few studies have emphasized the role of carbon nanomaterials in regulating the morphology of atomically doped Ni3S2 electrocatalysts. Carbon dots (CDs) possess abundant surface functional groups, unique electron storage capabilities, and highly efficient and stable reactive centers, making them a highly attractive new material in the field of catalysis. Therefore, proposing a carbon doped Fe-Ni3S2 electrocatalyst supported on nickel foam is very challenging.
[0004] Based on the above considerations, the inventors incorporated carbon dots into 2D Fe-Ni3S2 nanosheets loaded on nickel foam to enhance the electrocatalytic decomposition of urea for hydrogen production. This unique 0D-2D nanosheet structure design not only provides a larger specific surface area and abundant reaction sites in the electrocatalytic reaction, but also ensures sufficient contact between Fe-Ni3S2 and carbon dots, effectively promoting the adsorption and decomposition of urea and charge transfer during the reaction. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing carbon doped Fe-Ni3S2@NF (Fe-Ni3S2 / CDs@NF) electrocatalysts.
[0006] A method for preparing a carbon dot-doped Fe-Ni3S2@NF (Fe-Ni3S2 / CDs@NF) electrocatalyst includes: weighing sodium sulfide and dissolving it in deionized water, adding carbon dots and stirring evenly, placing Fe-Ni(OH)2 (Fe-Ni(OH)2@NF) grown on nickel foam into the mixture, transferring it to a reaction vessel and reacting hydrothermally at 110-180℃ for 4-10 hours, preferably at 120℃ for 6 hours, cooling to room temperature, washing three times with ethanol and water, and drying to obtain the catalyst. The solid-liquid ratio of sodium sulfide, carbon dots and deionized water is 480mg:0.5-4mg:30mL, preferably 480mg:2mg:30mL.
[0007] In a preferred embodiment of the present invention, the Fe-Ni(OH)2 (Fe-Ni(OH)2@NF) grown on nickel foam is prepared by: weighing nickel nitrate, ferric nitrate, urea, and ammonium fluoride, dissolving them in water and ultrasonically stirring, placing them in a reaction vessel, adding the treated nickel foam, and hydrothermally reacting them in a high-pressure vessel at 110-180°C for 4-10 hours, preferably at 120°C for 8 hours, cooling to room temperature, washing three times with ethanol and water, and drying to obtain Fe-Ni(OH)2. The solid-liquid ratio of nickel nitrate, ferric nitrate, urea, ammonium fluoride, and deionized water is 0.5815g:0.0897-0.808g:0.36g:0.15g:3ml, preferably 0.5815g:0.134g:0.36g:0.15g:3ml.
[0008] The foamed nickel has a clean surface and is free of impurities after pretreatment.
[0009] In a preferred embodiment of the present invention, the carbon dots are prepared in-house. A method for preparing carbon dots is disclosed below: citric acid and ethylenediamine are dissolved and dispersed evenly in deionized water, transferred to a reaction vessel, and subjected to hydrothermal reaction at 100–200°C for 4–1 hour, preferably at 180°C for 5 hours. The mixture is then naturally cooled to room temperature and dialyzed to obtain carbon dots. The solid-liquid ratio of citric acid:ethylenediamine:deionized water is 0.5–2 g:0.1–0.5 mL:5–20 mL, preferably 1.05 g:0.335 mL:10 mL.
[0010] Another objective of this invention is to use the Fe-Ni3S2 / CDs@NF prepared according to the above method as a non-precious metal electrocatalyst in urea fuel cells for the decomposition of urea to produce hydrogen. Simultaneously, electrocatalysis can also be used to address urea pollution in the environment and to reduce the overpotential of urea fuel cells.
[0011] The room-temperature electrochemical performance of the synthesized catalyst was tested on a CH760d electrochemical workstation (CH Instruments, Inc.). Graphite rods and Hg / HgO were used as the counter and reference electrodes, respectively. All polarization curves for all samples were collected by linear sweep voltammetry (LSV) at a scan rate of 5 mV / s, and the results were analyzed according to the Nernst equation E. RHE =E Hg / HgO The obtained LSV curve was calibrated to RHE by adding +0.0592×pH+0.098 to evaluate the catalytic activity of the electrocatalyst.
[0012] The morphology of the Fe-Ni3S2 / CDs@NF composite electrocatalyst prepared in this invention was determined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and its structure was determined by X-ray diffraction (XRD). Electrocatalytic experiments were conducted using a mixed solution of 1 M KOH + 0.3 M urea as the electrolyte, and the results, as detected by an electrochemical workstation, showed excellent electrocatalytic activity.
[0013] Beneficial effects
[0014] This invention first synthesizes Fe-Ni(OH)₂@NF nanosheets and carbon dots using a simple hydrothermal synthesis method. Then, during the sulfidation process of the Fe-Ni(OH)₂@NF nanosheets, surface-modified carbon dots are used to construct a Fe-Ni₃S₂ / CDs@NF nanocomposite electrocatalyst to enhance the electrocatalytic decomposition of urea for hydrogen production. This catalyst can also be used for electrolyzing urea in waste liquid and as a highly efficient catalyst in urea fuel cells. The process of this invention is very simple, inexpensive, and readily available, with low cost and short reaction time. Utilizing electrical energy to convert to hydrogen energy reduces energy consumption and reaction costs, facilitates mass production, is non-toxic and harmless, and meets the requirements of sustainable development. Attached Figure Description
[0015] Figure 1 XRD pattern of the Fe-Ni3S2 / CDs@NF electrocatalyst prepared in Example 1;
[0016] Figure 2 SEM image of the Fe-Ni3S2 / CDs@NF electrocatalyst prepared in Example 1;
[0017] Figure 3 TEM (a) and HRTEM (b) images of the Fe-Ni3S2 / CDs@NF electrocatalyst prepared in Example 1;
[0018] Figure 4 HER polarization curves (a) and UOR polarization curves (b) of Fe-Ni3S2 electrodes with different iron contents loaded on nickel foam and carbon doped on nickel foam, prepared in Example 1; HER polarization curves (c) and UOR polarization curves (d) of Fe-Ni3S2 electrodes with different carbon doping amounts loaded on nickel foam.
[0019] Figure 5 HER polarization curves (a) and UOR polarization curves (b) of the different composite materials prepared in Example 1.
[0020] Figure 6 LSV polarization curves (a) and HER and UOR polarization curves (b) of the different composite materials prepared in Example 1 for the fully decomposed urea. Detailed Implementation
[0021] The present invention will be described in detail below with reference to embodiments, so that those skilled in the art can better understand the present invention, but the present invention is not limited to the following embodiments.
[0022] Example 1
[0023] A method for preparing a carbon dot-doped Fe-Ni3S2@NF (Fe-Ni3S2 / CDs@NF) electrocatalyst includes the following steps:
[0024] (1) Dissolve 480 mg of sodium sulfide in 30 mL of deionized water, add a certain amount (0.5-4 mg) of carbon dot solution and stir for 1 h until the solution is evenly dispersed, then add Fe-Ni(OH)2 loaded on nickel foam.
[0025] (2) The mixed solution was transferred to a high-pressure reactor and kept at 120°C for 6 hours. After cooling to room temperature, it was washed three times with ethanol / water and dried to obtain Fe-Ni3S2 / CDs@NF.
[0026] The prepared Fe-Ni3S2 / CDs@NF, at 10 mA cm⁻¹ -2At the current density, the electromotive force of HER is 54mV, and the electromotive force of UOR is 1.34V.
[0027] Preparation of Fe-Ni(OH)2 loaded on nickel foam: Weigh 0.5815g nickel nitrate, 0.1347g ferric nitrate, 0.36g urea, and 0.15g ammonium fluoride, dissolve them in 30mL deionized water, stir until uniformly dispersed, add the treated nickel foam, and hydrothermally react in an autoclave at 120℃ for 8h. Cool to room temperature, wash three times with ethanol and water, and dry to obtain the final product.
[0028] Preparation of the carbon dots: Citric acid (1.05 g) and ethylenediamine (335 μ L) were dissolved in 10 mL of deionized water, transferred to a 20 mL reaction vessel, heated at 180 °C for 5 h, cooled to room temperature, and a brownish-black product was obtained. Carbon dots were obtained after dialysis.
[0029] Example 2
[0030] A method for preparing a carbon dot-doped Fe-Ni3S2@NF (Fe-Ni3S2 / CDs@NF) electrocatalyst includes the following steps:
[0031] (1) Dissolve 480 mg of sodium sulfide in 30 mL of deionized water, add 0.5 mg of carbon dot solution and stir for h until the solution is evenly dispersed, then add Fe-Ni(OH)2 loaded on nickel foam.
[0032] (2) The mixed solution was transferred to a high-pressure reactor and kept at 120°C for 6 hours. After cooling to room temperature, it was washed three times with ethanol / water and dried to obtain Fe-Ni3S2 / CDs@NF.
[0033] The prepared Fe-Ni3S2 / CDs@NF, at 10 mA cm⁻¹ -2 At the current density, the electromotive force of HER is 109 mV, and the electromotive force of UOR is 1.38 V.
[0034] Preparation of Fe-Ni(OH)2 loaded on nickel foam: Weigh 0.5815g nickel nitrate, 0.1347g ferric nitrate, 0.36g urea, and 0.15g ammonium fluoride, dissolve them in 30mL deionized water, stir until uniformly dispersed, add the treated nickel foam, and hydrothermally react in an autoclave at 120℃ for 8h. Cool to room temperature, wash three times with ethanol and water, and dry to obtain the final product.
[0035] Preparation of the carbon dots: Citric acid (1.05 g) and ethylenediamine (335 μ L) were dissolved in 10 mL of deionized water, transferred to a 20 mL reaction vessel, heated at 180 °C for 5 h, cooled to room temperature, and a brownish-black product was obtained. Carbon dots were obtained after dialysis.
[0036] Example 3
[0037] A method for preparing a carbon dot-doped Fe-Ni3S2@NF (Fe-Ni3S2 / CDs@NF) electrocatalyst includes the following steps:
[0038] (1) Dissolve 480 mg of sodium sulfide in 30 mL of deionized water, add 1 mg of carbon dot solution and stir for 1 h until the solution is evenly dispersed, then add Fe-Ni(OH)2 loaded on nickel foam.
[0039] (2) The mixed solution was transferred to a high-pressure reactor and kept at 120°C for 6 hours. After cooling to room temperature, it was washed three times with ethanol / water and dried to obtain Fe-Ni3S2 / CDs@NF.
[0040] The prepared Fe-Ni3S2 / CDs@NF, at 10 mA cm⁻¹ -2 At the current density, the electromotive force of HER is 106 mV, and the electromotive force of UOR is 1.37 V.
[0041] The preparation of Fe-Ni(OH)2 loaded on nickel foam is as follows: 0.5815g of nickel nitrate, 0.1347g of ferric nitrate, 0.36g of urea, and 0.15g of ammonium fluoride are weighed and dissolved in 30mL of deionized water. The mixture is stirred until it is evenly dispersed and then the treated nickel foam is added. The mixture is then subjected to hydrothermal reaction in an autoclave at 120℃ for 8 hours. After cooling to room temperature, the mixture is washed three times with ethanol and water, and then dried to obtain the final product.
[0042] Preparation of the carbon dots: Citric acid (1.05 g) and ethylenediamine (335 μ L) were dissolved in 10 mL of deionized water, transferred to a 20 mL reaction vessel, heated at 180 °C for 5 h, cooled to room temperature, and a brownish-black product was obtained. Carbon dots were obtained after dialysis.
[0043] Example 4
[0044] A method for preparing a carbon dot-doped Fe-Ni3S2@NF (Fe-Ni3S2 / CDs@NF) electrocatalyst includes the following steps:
[0045] (1) Dissolve 480 mg of sodium sulfide in 30 mL of deionized water, add 0.5 mg of carbon dot solution and stir for 1 h until the solution is evenly dispersed, then add Fe-Ni(OH)2 loaded on nickel foam.
[0046] (2) The mixed solution was transferred to a high-pressure reactor and kept at 120°C for 6 hours. After cooling to room temperature, it was washed three times with ethanol / water and dried to obtain Fe-Ni3S2 / CDs@NF.
[0047] The prepared Fe-Ni3S2 / CDs@NF, at 10 mA cm⁻¹ -2 At the current density, the electromotive force of HER is 54mV, and the electromotive force of UOR is 1.34V.
[0048] The preparation of Fe-Ni(OH)2 loaded on nickel foam is as follows: 0.5815g of nickel nitrate, 0.1347g of ferric nitrate, 0.36g of urea, and 0.15g of ammonium fluoride are weighed and dissolved in 30mL of deionized water. The mixture is stirred until it is evenly dispersed and then the treated nickel foam is added. The mixture is then subjected to hydrothermal reaction in an autoclave at 120℃ for 8 hours. After cooling to room temperature, the mixture is washed three times with ethanol and water, and then dried to obtain the final product.
[0049] Preparation of the carbon dots: Citric acid (1.05 g) and ethylenediamine (335 μ L) were dissolved in 10 mL of deionized water, transferred to a 20 mL reaction vessel, heated at 180 °C for 5 h, cooled to room temperature, and a brownish-black product was obtained. Carbon dots were obtained after dialysis.
[0050] Example 5
[0051] A method for preparing a carbon dot-doped Fe-Ni3S2@NF (Fe-Ni3S2 / CDs@NF) electrocatalyst includes the following steps:
[0052] (1) Dissolve 480 mg of sodium sulfide in 30 m of deionized water, add 0.5 mg of carbon dot solution and stir for 1 h until the solution is evenly dispersed, then add Fe-Ni(OH)2 loaded on nickel foam.
[0053] (2) The mixed solution was transferred to a high-pressure reactor and kept at 120°C for 6 hours. After cooling to room temperature, it was washed three times with ethanol / water and dried to obtain Fe-Ni3S2 / CDs@NF.
[0054] The prepared Fe-Ni3S2 / CDs@NF, at 10 mA cm⁻¹ -2 At the current density, the electromotive force of HER is 93mV, and the electromotive force of UOR is 1.37V.
[0055] The preparation of Fe-Ni(OH)2 loaded on nickel foam is as follows: 0.5815g of nickel nitrate, 0.1347g of ferric nitrate, 0.36g of urea, and 0.15g of ammonium fluoride are weighed and dissolved in 30mL of deionized water. The mixture is stirred until it is evenly dispersed and then the treated nickel foam is added. The mixture is then subjected to hydrothermal reaction in an autoclave at 120℃ for 8 hours. After cooling to room temperature, the mixture is washed three times with ethanol and water, and then dried to obtain the final product.
[0056] Preparation of the carbon dots: Citric acid (1.05 g) and ethylenediamine (335 μ L) were dissolved in 10 mL of deionized water, transferred to a 20 mL reaction vessel, heated at 180 °C for 5 h, cooled to room temperature, and a brownish-black product was obtained. Carbon dots were obtained after dialysis.
[0057] Electrocatalytic activity experiment of Fe-Ni3S2 / CDs@NF electrocatalyst
[0058] (1) Prepare an electrolyte solution with a concentration of 1M KOH + 0.3M urea;
[0059] (2) Fe-Ni3S2 / CDs@NF catalysts with different carbon doping contents were used as working electrodes, with a working electrode surface area of 1 cm². 2 ;
[0060] (3) Before testing, allow the working electrode to operate at 100 mV for s. -1 A 500-cycle test was performed to ensure complete polarization of the working electrode and to improve the accuracy of the test data. Graphite rods and Hg / HgO were used as the counter electrode and reference electrode, respectively. All polarization curves for all samples were collected using linear sweep voltammetry (LSV) at a scan rate of 5 mV / s, and the results were analyzed according to the Nernst equation E... RHE =E Hg / HgO The obtained LSV curve was calibrated to RHE by adding +0.0592*pH+0.098. The results were processed to obtain the cyclic voltammetry curve shown in Figure (5). The best catalytic performance was obtained when the nickel:iron content in Fe-Ni3S2 / CDs@NF was 6:1 and the carbon doping content was 2mg during the experiment. -2 At current density, the overpotential of HER is only 54mV, while the overpotential of UOR is 1.34V.
[0061] Characterization analysis of Fe-Ni3S2 / CDs@NF
[0062] like Figure 1 The XRD diffraction patterns of Fe-Ni3S2 / CDs@NF and Fe-Ni3S2@NF nanocomposites are shown. The XRD pattern of the Fe-Ni3S2 / CDs@NF composite is similar to that of Fe-Ni3S2@NF. A set of diffraction peaks at 22.1, 31.5, 38.2, 50.1, and 55.4 points to the cubic phases (101), (110), (003), (113), and (122) of the phase standard card (PDF#44-1418), indicating that the addition of Fe and CDs did not significantly change the crystal structure of Ni3S2, indicating that CDs were successfully introduced into the composite material.
[0063] like Figure 2As shown, in the Fe-Ni3S2 / CDs@NF composite material, the catalyst clearly exhibits a nanosheet structure. This vertical nanosheet structure can expose more active sites, thereby improving catalytic performance.
[0064] like Figure 3 As shown in Figure a, carbon dots are clearly found to be uniformly distributed on the surface of Fe-Ni3S2 nanosheets in the Fe-Ni3S2 / CDs@NF composite material, and the two exhibit a tight bond. Figure 3 b presents an HRTEM image of the Fe-Ni3S2 / CDs composite, showing that the 0.29 nm lattice spacing belongs to the (110) plane of Ni3S2, while the 0.42 nm and 0.22 nm lattice spacings are attributed to the (010) plane of Ni3S2 and the (101) plane of carbon dots, respectively, indicating that the carbon quantum dots are tightly adhered to the surface of Ni3S2 nanosheets. With the introduction of Fe and carbon dots, Ni3S2 can effectively change its internal electronic structure with the dual assistance of metallic iron and carbon dots, thereby improving its electrocatalytic activity.
[0065] like Figure 4 As shown in the figure, it can be clearly seen that when the nickel:iron ratio is 6:1 and the carbon doping amount during the experiment is 2mg, the Fe-Ni3S2 / CDs@NF composite electrocatalyst has the best electrocatalytic electromotive force.
[0066] like Figure 5 As shown in the figure, it is clear that the catalytic performance of Fe-Ni3S2@NF without carbon dots is not as good as that of Fe-Ni3S2 / CDs@NF with carbon dots. With the dual assistance of Fe and carbon dots, the Fe-Ni3S2 / CDs@NF composite electrocatalyst has the best electrocatalytic electromotive force.
[0067] like Figure 6 As shown in the figure, it can be clearly seen that the introduction of carbon dots can improve the catalytic performance of Fe-Ni3S2@NF catalyst, and Fe-Ni3S2 / CDs@NF has the minimum electromotive force when it decomposes urea.
[0068] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.
Claims
1. A method for preparing a carbon dot-doped Fe-Ni3S2@NF electrocatalyst, characterized in that, The process includes: dissolving sodium sulfide in deionized water, adding carbon dots and stirring until homogeneous, placing Fe-Ni(OH)₂ grown on nickel foam into the solution, transferring the solution to a reactor, and reacting hydrothermally at 110–180°C for 4–10 hours. After cooling to room temperature, the solution is washed three times with ethanol and water, and then dried to obtain the final product. The Fe-Ni(OH)2 grown on nickel foam is prepared by dissolving nickel nitrate, ferric nitrate, urea, and ammonium fluoride in water and ultrasonically stirring. The solution is placed in a reaction vessel and the treated nickel foam is added. The mixture is then subjected to hydrothermal reaction in a high-pressure vessel at 110–180°C for 4–10 hours. After cooling to room temperature, the mixture is washed three times with ethanol and water, and then dried to obtain Fe-Ni(OH)2. The solid-liquid ratio of nickel nitrate, ferric nitrate, urea, ammonium fluoride, and deionized water is 0.5815 g: 0.0897–0.808 g: 0.36 g: 0.15 g: 3 ml. The carbon dots are prepared by dissolving citric acid and ethylenediamine in deionized water and dispersing them evenly, transferring them to a reaction vessel, and hydrothermally reacting them at 100-200°C for 4-1 hour. After naturally cooling to room temperature, they are dialyzed to obtain the carbon dots. The solid-liquid ratio of citric acid:ethylenediamine:deionized water is 0.5-2 g:0.1-0.5 mL:5-20 mL. The solid-liquid ratio of sodium sulfide, carbon dots, and deionized water is 480 mg: 0.5–4 mg: 30 mL.
2. The preparation method of the carbon dot-doped Fe-Ni3S2@NF electrocatalyst according to claim 1, characterized in that: The Fe-Ni(OH)2 grown on nickel foam is placed into it and then transferred to a reactor to react at 120°C for 6 hours.
3. The method for preparing the carbon dot-doped Fe-Ni3S2@NF electrocatalyst according to claim 1, characterized in that: The solid-liquid ratio of sodium sulfide, carbon dots, and deionized water is 480 mg: 2 mg: 30 ml.
4. The method for preparing the carbon dot-doped Fe-Ni3S2@NF electrocatalyst according to claim 1, characterized in that: The nickel nitrate, ferric nitrate, urea, and ammonium fluoride were weighed, dissolved in water, and ultrasonically stirred. The mixture was then placed in a reaction vessel, and the treated foamed nickel was added. The mixture was then subjected to a hydrothermal reaction at 120°C for 8 hours.
5. The method for preparing the carbon dot-doped Fe-Ni3S2@NF electrocatalyst according to claim 1, characterized in that: The solid-liquid ratio of nickel nitrate, ferric nitrate, urea, ammonium fluoride, and deionized water is 0.5815g:0.134g:0.36g:0.15g:3ml.
6. The method for preparing the carbon dot-doped Fe-Ni3S2@NF electrocatalyst according to claim 1, characterized in that: Citric acid and ethylenediamine were dissolved in deionized water and dispersed evenly. The mixture was then transferred to a reaction vessel and reacted at 180°C for 5 hours. After naturally cooling to room temperature, the mixture was dialyzed to obtain the final product.
7. The method for preparing the carbon dot-doped Fe-Ni3S2@NF electrocatalyst according to claim 1, characterized in that: The solid-liquid ratio of citric acid: ethylenediamine: deionized water is 1.05g: 0.335mL: 10mL.
8. The application of a carbon dot-doped Fe-Ni3S2@NF electrocatalyst prepared by any one of claims 1-7, characterized in that: The electrocatalyst is used for the electrocatalytic decomposition of urea to produce hydrogen.