A Co3S4 nanocatalyst rich in sulfur vacancies, its preparation method and application

Abstract

The present invention discloses a Co3S4 nanocatalyst rich in sulfur vacancies, its preparation method and application. Using cobalt chloride, ammonium fluoride, and urea as raw materials, the Co3S4 nanocatalyst is synthesized by a hydrothermal method. The raw material cost is low and the preparation method is simple. Then, a Co3S4 nanoflower with a spinel-type structure rich in sulfur vacancies is obtained through a reduction method. By controlling the reduction time, more active areas are increased and more active sites are exposed, showing good activity and product selectivity in electrocatalytic oxygen evolution and hydrogen evolution reactions.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalysis, and particularly relates to a Co3S4 nanocatalyst rich in sulfur vacancies, a preparation method thereof, and an application thereof. Background Art

[0002] Under the background of the increasingly severe energy crisis and environmental pollution, new energy development and conversion technologies such as water electrolysis will provide strong support for the implementation of the sustainable energy development strategy by all mankind in the future. However, there are many restrictive factors in the large-scale commercialization process of water electrolysis technology. The biggest restriction lies in the lack of efficient, inexpensive, and stable non-precious metal-based OER and HER electrocatalysts.

[0003] Thiospinel (AB2S4) has an exact structure and composition, rich electron configurations and valence states, and a unique electronic structure. It has catalytic activity comparable to that of noble metal-based catalysts and is considered to be one of the most promising non-precious metal catalysts. However, due to the limitations of its own structure, the active sites of the spinel are not fully exposed, and the poor mass transfer performance and conductivity result in the catalytic activity not being utilized to the maximum extent. In recent years, researchers have used means such as atomic doping, introducing vacancies, or constructing heterojunctions to regulate the electronic structure of spinels and improve catalytic activity, thereby expanding the application scope of spinels. Among them, introducing anion vacancies into the lattice structure can significantly improve the conductivity of the catalyst, while introducing vacancies into the spinel structure can accelerate charge transfer and electron transport, generate more active sites, thereby optimizing the structure and electronic properties of the catalyst, improving the activity and stability of the catalyst, and becoming one of the effective means to enhance the electrocatalytic performance of spinels.

[0004] Therefore, it is particularly urgent and challenging to develop and design a general strategy for synthesizing a spinel catalyst rich in sulfur vacancies with a simple synthesis method, inexpensive precursors, high efficiency, and stability. Summary of the Invention

[0005] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Simplifications or omissions may be made in this part, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this part, the abstract, and the title. However, such simplifications or omissions shall not be used to limit the scope of the present invention.

[0006] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a preparation method for a Co3S4 nanocatalyst rich in sulfur vacancies.

[0008] To solve the above technical problems, the present invention provides the following technical solutions: including,

[0009] Cobalt chloride, ammonium fluoride, and urea are dissolved in deionized water and stirred at room temperature to form a mixed solution;

[0010] The pretreated nickel foam and the mixed solution are used to prepare a Co precursor through a hydrothermal reaction;

[0011] The Co precursor is sulfided to obtain a Co3S4 nanocatalyst;

[0012] The Co3S4 is immersed in an aqueous NaBH4 solution for reduction;

[0013] After the reaction is completed and dried, a Co3S4 nanocatalyst rich in sulfur vacancies is obtained.

[0014] As a preferred embodiment of the preparation method of the Co3S4 nanocatalyst rich in sulfur vacancies of the present invention, wherein: the molar amount of cobalt chloride is 1-4 mmol, the molar amount of ammonium fluoride is 2-5 mmol, and the molar amount of urea is 3-6 mmol.

[0015] As a preferred embodiment of the preparation method of the Co3S4 nanocatalyst rich in sulfur vacancies of the present invention, wherein: the pretreatment of the nickel foam includes washing the nickel foam with acetone, ethanol, and ultrapure water respectively and then drying it in vacuum.

[0016] As a preferred embodiment of the preparation method of the Co3S4 nanocatalyst rich in sulfur vacancies of the present invention, wherein: for the hydrothermal reaction, the reaction temperature is 100-150 °C and the reaction time is 10-20 h.

[0017] As a preferred embodiment of the preparation method of the Co3S4 nanocatalyst rich in sulfur vacancies of the present invention, wherein: for the sulfidation treatment, the treatment temperature is 150-200 °C and the treatment time is 10-20 h.

[0018] As a preferred embodiment of the preparation method of the Co3S4 nanocatalyst rich in sulfur vacancies of the present invention, wherein: the Co3S4 is immersed in an aqueous NaBH4 solution for reduction, wherein the concentration of NaBH4 is 0.1-0.5 mol / L and the reduction time is 5-30 min.

[0019] Another object of the present invention is to overcome the deficiencies in the prior art and provide a spinel-type Co3S4 nanocatalyst prepared by the preparation method of the Co3S4 nanocatalyst rich in sulfur vacancies.

[0020] Another object of the present invention is to overcome the deficiencies in the prior art and provide an application of the Co3S4 nanocatalyst rich in sulfur vacancies.

[0021] As a preferred embodiment of the preparation method of the sulfur vacancy-rich Co3S4 nanocatalyst of the present invention, wherein: the application includes using it as an electrocatalyst in water electrolysis.

[0022] As a preferred embodiment of the preparation method of the sulfur vacancy-rich Co3S4 nanocatalyst of the present invention, wherein: the Co3S4 nanocatalyst serves as a working electrode in a three-electrode system, where, at a current density of 100 mA / cm -2 , the overpotential of the oxygen evolution reaction (OER) is only 245 mV; at a current density of 10 mA / cm -2 , the overpotential of the hydrogen evolution reaction (HER) is only 45 mV.

[0023] As a preferred embodiment of the preparation method of the sulfur vacancy-rich Co3S4 nanocatalyst of the present invention, wherein: the Co3S4 nanocatalyst serves as the cathode and anode in a two-electrode system. When applied to overall water splitting, only 1.53 V is required to reach a current density of 20 mA / cm -2 .

[0024] Advantages of the present invention:

[0025] (1) The present invention synthesizes the Co3S4 nanocatalyst using cobalt chloride, ammonium fluoride, and urea as raw materials. The raw materials used have low costs and the preparation method is simple, having obvious advantages in practical applications.

[0026] (2) The present invention reduces the Co3S4 nanocatalyst through NaBH4 to construct a spinel-type Co3S4 nanocatalyst rich in sulfur vacancies. No additional equipment is required during the process, and the reduction is achieved under normal temperature conditions. The method is simple and effective, solving the deficiencies of other complex synthesis methods in the prior art that are difficult to prepare on a large scale.

[0027] (3) The electrocatalyst prepared by the method of the present invention has excellent performance. By controlling the reduction time to control the active area of the catalyst, the catalyst exhibits the best catalytic activity and product selectivity in the electrocatalytic oxygen evolution and hydrogen evolution reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings. Among them:

[0029] Figure 1 is the XRD pattern of the V s -Co3S4@NF electrocatalyst prepared in Example 1 of the present invention.

[0030] Figure 2 V prepared in Example 1 of the present invention s HRTEM image of the V-Co3S4@NF electrocatalyst

[0031] Figure 3 V prepared in Example 1 of the present invention s LSV graph of the OER performance of V-Co3S4@NF in a three-electrode system

[0032] Figure 4 V prepared in Example 1 of the present invention s LSV graph of the HER performance of V-Co3S4@NF in a three-electrode system

[0033] Figure 5 V prepared in Example 1 of the present invention s LSV graph of the overall water splitting performance of V-Co3S4@NF in a two-electrode system

[0034] Figure 6 Comparison graph of the OER performance of the products prepared in Examples 1 to 7 and Comparative Examples 1 and 2 of the present invention in a three-electrode system

[0035] Figure 7 Comparison graph of the HER performance of the products prepared in Examples 1 to 7 and Comparative Examples 1 and 2 of the present invention in a three-electrode system

[0036] Figure 8 Comparison graph of the overall water splitting performance of the products prepared in Examples 1 to 7 and Comparative Examples 1 and 2 of the present invention in a two-electrode system Detailed implementation manners

[0037] To make the above objects, features and advantages of the present invention more obvious and understandable, the following describes the detailed implementation manners of the present invention in conjunction with the embodiments of the specification.

[0038] Many specific details are set forth in the following description in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar promotions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0039] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure or characteristic that can be included in at least one implementation manner of the present invention. The appearances of "in one embodiment" in different places in this specification do not all refer to the same embodiment, nor are they separate or alternative embodiments that exclude each other with other embodiments.

[0040] Unless otherwise specified, the raw materials used in the present invention are all commercially available.

[0041] The corresponding relationship between the names and chemical formulas of the raw materials used in the present invention is shown in Table 1.

[0042] Table 1 Corresponding Table of Chemical Names

[0043] Cobalt chloride <![CDATA[CoCl2·6H2O]]> Ammonium fluoride <![CDATA[NH4F]]> Urea <![CDATA[CO(NH2)2]]> Sodium sulfide <![CDATA[Na2S]]>

[0044] Example 1

[0045] The nickel foam was cut into small pieces of 12 cm 2 and ultrasonically treated in acetone, ethanol, and ultrapure water for 30 min respectively, and then dried in vacuum at 60 °C. The product was denoted as NF;

[0046] 1 mmol of cobalt chloride, 2 mmol of urea, and 3 mmol of ammonium fluoride were respectively dissolved in 30 mL of deionized water and stirred at room temperature to form a mixed solution;

[0047] NF was immersed in the mixed solution for hydrothermal reaction. The reaction temperature was 120 °C and the reaction time was 15 h. After the reaction, it was dried in vacuum at 60 °C for 6 h to obtain the Co precursor, and the product was denoted as Co-P@NF;

[0048] 0.2 mmol of sodium sulfide was dissolved in 30 mL of ultrapure water and stirred for 10 min to obtain a sodium sulfide solution. Co-P@NF was placed in the solution for sulfidation treatment. The treatment temperature was 160 °C and the treatment time was 15 h. After the reaction, it was rinsed with ethanol and ultrapure water respectively, and dried in vacuum at 60 °C for 6 h to obtain the Co3S4 nanocatalyst, denoted as Co3S4@NF;

[0049] Co3S4@NF was immersed in an aqueous solution of NaBH4 with a concentration of 0.2 mol / L for 10 min for reduction reaction. After the reaction, the product was rinsed with ultrapure water and dried in vacuum at 60 °C for 6 h to obtain the sulfur vacancy-rich Co3S4 nanocatalyst, denoted as Vs-Co3S4@NF.

[0050] Figure 1 、 Figure 2 are the XRD pattern and HR TEM pattern of the V s -Co3S4@NF electrocatalyst prepared in this example. It can be clearly seen from the figure the lattice fringes of the V s -Co3S4@NF electrocatalyst, corresponding to the (220) crystal plane of Co3S4. At the same time, it can be observed that there is partial lattice disorder, indicating that sulfur vacancies are successfully introduced into the Co3S4 electrocatalyst, demonstrating the successful preparation of the V s -Co3S4@NF electrocatalyst.

[0051] Example 2

[0052] Cut the nickel foam into small pieces of 12 cm 2 , ultrasonically treat them in acetone, ethanol, and ultrapure water for 30 min respectively, and then dry them in vacuum at 60 °C. The product is denoted as NF;

[0053] Weigh 1 mmol of cobalt chloride, 2 mmol of urea, and 3 mmol of ammonium fluoride successively and dissolve them in 30 mL of deionized water, and stir at room temperature to form a mixed solution;

[0054] Immerse NF in the mixed solution for hydrothermal reaction. The reaction temperature is 120 °C and the reaction time is 15 h. After the reaction, dry it in vacuum at 60 °C for 6 h to obtain the Co precursor, and the product is denoted as Co-P@NF;

[0055] Weigh 0.2 mmol of sodium sulfide and dissolve it in 30 mL of ultrapure water, stir for 10 min to obtain a sodium sulfide solution. Place Co-P@NF in the solution for sulfidation treatment. The treatment temperature is 160 °C and the treatment time is 15 h. After the reaction, wash it with ethanol and ultrapure water respectively, and dry it in vacuum at 60 °C for 6 h to obtain the Co3S4 nanocatalyst, denoted as Co3S4@NF;

[0056] Immerse Co3S4@NF in an aqueous solution of NaBH4 with a concentration of 0.2 mol / L for 5 min for reduction reaction. After the reaction, wash the product with ultrapure water and dry it in vacuum at 60 °C for 6 h to obtain the sulfur vacancy-rich Co3S4 nanocatalyst, denoted as Vs-Co3S4@NF.

[0057] Example 3

[0058] Cut the nickel foam into small pieces of 12 cm 2 , ultrasonically treat them in acetone, ethanol, and ultrapure water for 30 min respectively, and then dry them in vacuum at 60 °C. The product is denoted as NF;

[0059] Weigh 1 mmol of cobalt chloride, 2 mmol of urea, and 3 mmol of ammonium fluoride successively and dissolve them in 30 mL of deionized water, and stir at room temperature to form a mixed solution;

[0060] Immerse NF in the mixed solution for hydrothermal reaction. The reaction temperature is 120 °C and the reaction time is 15 h. After the reaction, dry it in vacuum at 60 °C for 6 h to obtain the Co precursor, and the product is denoted as Co-P@NF;

[0061] Weigh 0.2 mmol of sodium sulfide and dissolve it in 30 mL of ultrapure water. Stir for 10 min to obtain a sodium sulfide solution. Place Co-P@NF in the solution for sulfidation treatment. The treatment temperature is 160 °C and the treatment time is 15 h. After the reaction, wash it with ethanol and ultrapure water respectively, and dry it in vacuum at 60 °C for 6 h to obtain the Co3S4 nanocatalyst, denoted as Co3S4@NF;

[0062] Soak Co3S4@NF in an aqueous solution of NaBH4 with a concentration of 0.2 mol / L for 15 min for the reduction reaction. After the reaction, wash the product with ultrapure water and dry it in vacuum at 60 °C for 6 h to obtain the sulfur vacancy-rich Co3S4 nanocatalyst, denoted as Vs-Co3S4@NF.

[0063] Example 4

[0064] Cut the nickel foam into small pieces of 12 cm 2 and ultrasonically treat them in acetone, ethanol, and ultrapure water for 30 min respectively, then dry them in vacuum at 60 °C. The product is denoted as NF;

[0065] Weigh 1 mmol of cobalt chloride, 2 mmol of urea, and 3 mmol of ammonium fluoride and dissolve them in 30 mL of deionized water successively. Stir at room temperature to form a mixed solution;

[0066] Immerse NF in the mixed solution for hydrothermal reaction. The reaction temperature is 120 °C and the reaction time is 15 h. After the reaction, dry it in vacuum at 60 °C for 6 h to obtain the Co precursor, and the product is denoted as Co-P@NF;

[0067] Weigh 0.2 mmol of sodium sulfide and dissolve it in 30 mL of ultrapure water. Stir for 10 min to obtain a sodium sulfide solution. Place Co-P@NF in the solution for sulfidation treatment. The treatment temperature is 160 °C and the treatment time is 15 h. After the reaction, wash it with ethanol and ultrapure water respectively, and dry it in vacuum at 60 °C for 6 h to obtain the Co3S4 nanocatalyst, denoted as Co3S4@NF;

[0068] Soak Co3S4@NF in an aqueous solution of NaBH4 with a concentration of 0.2 mol / L for 20 min for the reduction reaction. After the reaction, wash the product with ultrapure water and dry it in vacuum at 60 °C for 6 h to obtain the sulfur vacancy-rich Co3S4 nanocatalyst, denoted as Vs-Co3S4@NF.

[0069] Example 5

[0070] Cut the nickel foam into small pieces of 12 cm 2 and ultrasonically treat them in acetone, ethanol, and ultrapure water for 30 min respectively, then dry them in vacuum at 60 °C. The product is denoted as NF;

[0071] Weigh 1 mmol of cobalt chloride, 2 mmol of urea, and 3 mmol of ammonium fluoride successively and dissolve them in 30 mL of deionized water. Stir at room temperature to form a mixed solution.

[0072] Immerse NF in the mixed solution for hydrothermal reaction. The reaction temperature is 120 °C and the reaction time is 15 h. After the reaction, dry it in vacuum at 60 °C for 6 h to obtain the Co precursor, and the product is denoted as Co-P@NF.

[0073] Weigh 0.2 mmol of sodium sulfide and dissolve it in 30 mL of ultrapure water. Stir for 10 min to obtain a sodium sulfide solution. Place Co-P@NF in the solution for sulfidation treatment. The treatment temperature is 160 °C and the treatment time is 5 h. After the reaction, wash it with ethanol and ultrapure water respectively, and dry it in vacuum at 60 °C for 6 h to obtain the Co3S4 nanocatalyst, denoted as Co3S4@NF.

[0074] Immerse Co3S4@NF in an aqueous solution of NaBH4 with a concentration of 0.2 mol / L for 10 min for reduction reaction. After the reaction, wash the product with ultrapure water and dry it in vacuum at 60 °C for 6 h to obtain the sulfur vacancy-rich Co3S4 nanocatalyst, denoted as Vs-Co3S4@NF.

[0075] Example 6

[0076] Cut the nickel foam into small pieces of 12 cm 2 and ultrasonically treat them in acetone, ethanol, and ultrapure water for 30 min respectively, then dry them in vacuum at 60 °C. The product is denoted as NF.

[0077] Weigh 1 mmol of cobalt chloride, 2 mmol of urea, and 3 mmol of ammonium fluoride successively and dissolve them in 30 mL of deionized water. Stir at room temperature to form a mixed solution.

[0078] Immerse NF in the mixed solution for hydrothermal reaction. The reaction temperature is 120 °C and the reaction time is 15 h. After the reaction, dry it in vacuum at 60 °C for 6 h to obtain the Co precursor, and the product is denoted as Co-P@NF.

[0079] Weigh 0.2 mmol of sodium sulfide and dissolve it in 30 mL of ultrapure water. Stir for 10 min to obtain a sodium sulfide solution. Place Co-P@NF in the solution for sulfidation treatment. The treatment temperature is 160 °C and the treatment time is 10 h. After the reaction, wash it with ethanol and ultrapure water respectively, and dry it in vacuum at 60 °C for 6 h to obtain the Co3S4 nanocatalyst, denoted as Co3S4@NF.

[0080] The Co3S4@NF was immersed in an aqueous solution of NaBH4 with a concentration of 0.2 mol / L for 10 min for the reduction reaction. After the reaction, the product was rinsed with ultrapure water and dried in vacuo at 60 °C for 6 h, thus obtaining a sulfur vacancy-rich Co3S4 nanocatalyst, denoted as Vs-Co3S4@NF.

[0081] Example 7

[0082] The nickel foam was cut into small pieces of 12 cm 2 and ultrasonically treated in acetone, ethanol, and ultrapure water for 30 min respectively, and then dried in vacuo at 60 °C. The product was denoted as NF;

[0083] 1 mmol of cobalt chloride, 2 mmol of urea, and 3 mmol of ammonium fluoride were respectively dissolved in 30 mL of deionized water and stirred at room temperature to form a mixed solution;

[0084] NF was immersed in the mixed solution for hydrothermal reaction. The reaction temperature was 120 °C and the reaction time was 15 h. After the reaction, it was dried in vacuo at 60 °C for 6 h to obtain a Co precursor, and the product was denoted as Co-P@NF;

[0085] 0.2 mmol of sodium sulfide was weighed and dissolved in 30 mL of ultrapure water and stirred for 10 min to obtain a sodium sulfide solution. Co-P@NF was placed in the solution for sulfidation treatment. The treatment temperature was 160 °C and the treatment time was 20 h. After the reaction, it was rinsed with ethanol and ultrapure water respectively, and dried in vacuo at 60 °C for 6 h to obtain a Co3S4 nanocatalyst, denoted as Co3S4@NF;

[0086] The Co3S4@NF was immersed in an aqueous solution of NaBH4 with a concentration of 0.2 mol / L for 10 min for the reduction reaction. After the reaction, the product was rinsed with ultrapure water and dried in vacuo at 60 °C for 6 h, thus obtaining a sulfur vacancy-rich Co3S4 nanocatalyst, denoted as Vs-Co3S4@NF.

[0087] Comparative Example 1

[0088] The nickel foam was cut into small pieces of 12 cm 2 and ultrasonically treated in acetone, ethanol, and ultrapure water for 30 min respectively, and then dried in vacuo at 60 °C. The product was denoted as NF;

[0089] 1 mmol of cobalt chloride, 2 mmol of urea, and 3 mmol of ammonium fluoride were respectively dissolved in 30 mL of deionized water and stirred at room temperature to form a mixed solution;

[0090] NF was immersed in the mixed solution for hydrothermal reaction. The reaction temperature was 120 °C and the reaction time was 15 h. After the reaction, it was dried in vacuo at 60 °C for 6 h to obtain a Co precursor, and the product was denoted as Co-P@NF.

[0091] Comparative Example 2

[0092] Cut the nickel foam into small pieces of 12 cm 2 , ultrasonically treat them in acetone, ethanol, and ultrapure water for 30 min respectively, and then dry them in vacuum at 60 °C. The product is denoted as NF;

[0093] Weigh 1 mmol of cobalt chloride, 2 mmol of urea, and 3 mmol of ammonium fluoride successively and dissolve them in 30 mL of deionized water, and stir at room temperature to form a mixed solution;

[0094] Immerse NF in the mixed solution for hydrothermal reaction. The reaction temperature is 120 °C, the reaction time is 15 h. After the reaction, dry it in vacuum at 60 °C for 6 h to obtain the Co precursor, and the product is denoted as Co-P@NF;

[0095] Weigh 0.2 mmol of sodium sulfide and dissolve it in 30 mL of ultrapure water, stir for 10 min to obtain a sodium sulfide solution. Place Co-P@NF in the solution for sulfidation treatment. The treatment temperature is 160 °C, the treatment time is 15 h. After the reaction, cool it to room temperature, wash it with ethanol and ultrapure water, and dry it in vacuum at 60 °C for 6 h to obtain the Co3S4 nanocatalyst, denoted as Co3S4@NF.

[0096] Use the products prepared in each example and comparative example of the present invention as catalysts in the electrocatalytic reaction.

[0097] In a three-electrode system, use the product catalyst as the working electrode, the Hg / HgO electrode and the carbon rod as the reference electrode and the counter electrode respectively. Then test its OER and HER performance in 1 M KOH. The LSV curve sweep rate is 5 mV / s, and the EIS range is 0.01 - 100 KHz;

[0098] In a two-electrode system, use the product catalyst as the anode and cathode respectively to assemble an electrolytic cell, and test its overall water splitting performance in 1 M KOH. The LSV curve sweep rate is 5 mV / s.

[0099] Figures 3 to 5 Respectively, the LSV diagram of the OER performance, the LSV diagram of the HER performance, and the LSV diagram of the overall water splitting performance in the two-electrode system of V s -Co3S4@NF prepared in Example 1 of the present invention.

[0100] As Figures 3 to 5 shown, at a current density of 100 mA / cm -2 in the three-electrode system, the OER overpotential is only 245 mV; at 10 mA / cm -2At a current density of, the HER overpotential is only 45 mV; in the overall water splitting performance test, only 1.53 V is required to reach a current density of 20 mA / cm². -2 of the current density.

[0101] The above test results show that the electrocatalyst prepared by the present invention has excellent OER, HER, and overall water splitting performance.

[0102] Figure 6 Figure 9 is a comparison chart of the OER performance of the product catalysts of Examples 1 to 7 and Comparative Examples 1 and 2 of the present invention in a three-electrode system. From left to right are Examples 1 to 7, Comparative Example 1, and Comparative Example 2. At a current density of 100 mA / cm² in the three-electrode system, the OER overpotentials of the product catalysts of each example are 245 mV, 300 mV, 259 mV, 380 mV, 358 mV, 302 mV, 289 mV, 500 mV, and 330 mV respectively; -2 of the current density, the OER overpotentials of the product catalysts of each example are 245 mV, 300 mV, 259 mV, 380 mV, 358 mV, 302 mV, 289 mV, 500 mV, and 330 mV respectively;

[0103] Figure 7 Figure 15 is a comparison chart of the HER performance of the product catalysts of Examples 1 to 7 and Comparative Examples 1 and 2 of the present invention in a three-electrode system. From left to right are Examples 1 to 7, Comparative Example 1, and Comparative Example 2. At a current density of 10 mA / cm² in the three-electrode system, the HER overpotentials of the product catalysts of each example are 45 mV, 156 mV, 101 mV, 201 mV, 263 mV, 226 mV, 189 mV, 306 mV, and 240 mV respectively; -2 of the current density, the HER overpotentials of the product catalysts of each example are 45 mV, 156 mV, 101 mV, 201 mV, 263 mV, 226 mV, 189 mV, 306 mV, and 240 mV respectively;

[0104] From Figure 6 , Figure 7 it can be seen that the sulfur vacancy-rich Co₃S₄ nanocatalyst provided by the present invention shows more excellent OER and HER performance compared to the un-sulfurized Co catalyst and the Co₃S₄ nanocatalyst without sulfur vacancies. At the same time, the method of the present invention controls the active area of the catalyst by controlling the reduction time, so that the catalyst shows the best catalytic activity in the electrocatalytic oxygen evolution and hydrogen evolution reactions.

[0105] Figure 8 Figure 28 is a comparison chart of the overall water splitting performance of the product catalysts of Examples 1 to 7 and Comparative Examples 1 and 2 of the present invention. Each example reaches a current density of 20 mA / cm² at 1.53 V, 1.95 V, 1.78 V, 1.89 V, 1.91 V, 1.79 V, 1.75 V, 2.05 V, and 1.61 V respectively. It can be seen that the catalyst prepared by the present invention still shows good performance when applied to overall water splitting. -2 of the current density. It can be seen that the catalyst prepared by the present invention still shows good performance when applied to overall water splitting.

[0106] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A preparation method of a Co3S4 nanocatalyst rich in sulfur vacancies, characterized in that: Including, Cobalt chloride, ammonium fluoride, and urea are dissolved in deionized water and stirred at room temperature to form a mixed solution; The pretreated nickel foam and the mixed solution are used to prepare a Co precursor through a hydrothermal reaction; The Co precursor is sulfided to obtain a Co3S4 nanocatalyst; The Co3S4 is immersed in an aqueous NaBH4 solution for reduction; After the reaction ends and it is dried, a Co3S4 nanocatalyst rich in sulfur vacancies is obtained; Among them, the time for the sulfidation treatment is 10 - 20 h, and the time for the reduction is 5 - 30 min.

2. The preparation method of the Co3S4 nanocatalyst rich in sulfur vacancies according to claim 1, characterized in that: The molar amount of the cobalt chloride is 1 - 4 mmol, the molar amount of the ammonium fluoride is 2 - 5 mmol, and the molar amount of the urea is 3 - 6 mmol.

3. The preparation method of the Co3S4 nanocatalyst rich in sulfur vacancies according to claim 1, characterized in that: The pretreatment of the nickel foam includes cleaning the nickel foam with acetone, ethanol, and ultrapure water respectively and then drying it in vacuum.

4. The preparation method of the Co3S4 nanocatalyst rich in sulfur vacancies according to claim 1, characterized in that: For the hydrothermal reaction, the reaction temperature is 100 - 150 °C and the reaction time is 10 - 20 h.

5. The preparation method of the Co3S4 nanocatalyst rich in sulfur vacancies according to claim 1, characterized in that: For the sulfidation treatment, the treatment temperature is 150 - 200 °C.

6. The preparation method of the Co3S4 nanocatalyst rich in sulfur vacancies according to claim 1, characterized in that: The Co3S4 is immersed in an aqueous NaBH4 solution for reduction, where the concentration of NaBH4 is 0.1 - 0.5 mol / L.

7. The Co3S4 nanocatalyst rich in sulfur vacancies prepared by the method according to any one of claims 1 to 6, characterized in that: The Co3S4 nanocatalyst is a spinel type rich in sulfur vacancies.

8. The application of the Co3S4 nanocatalyst rich in sulfur vacancies according to claim 7, characterized in that: The application includes being used as an electrocatalyst in water electrolysis.

9. The application of the Co3S4 nanocatalyst rich in sulfur vacancies according to claim 8, characterized in that: The Co3S4 nanocatalyst serves as a working electrode in a three-electrode system, where the OER overpotential is only 245 mV at a current density of 100 mA / cm -2 ; and the HER overpotential is only 45 mV at a current density of 10 mA / cm -2 .

10. The application of the Co3S4 nanocatalyst rich in sulfur vacancies according to claim 8, characterized in that: When the Co3S4 nanocatalyst is used as the cathode and anode in a two-electrode system for overall water splitting, only 1.53 V is required to achieve a current density of 20 mA / cm -2 .

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