A method for preparing CuS@C / MoS2 composite material

Abstract

This invention provides a method for preparing CuS@C / MoS2 composite materials. The method includes: dissolving copper sulfate and sodium citrate in deionized water to obtain solution A; adding sodium hydroxide solution and ascorbic acid solution sequentially to solution A, stirring for a period of time, and aging to obtain cuprous oxide; mixing cuprous oxide-methanol solution and dopamine-methanol solution to obtain solution D, and obtaining polydopamine-coated cuprous oxide (Cu2O@PDA) by centrifugation, washing, and drying; placing Cu2O@PDA powder in a tube furnace under an argon atmosphere to obtain Cu2O@C powder; adding ammonium molybdate and thiourea to Cu2O@C aqueous solution to obtain solution E; transferring solution E to a reaction vessel for hydrothermal reaction, cooling, centrifuging, washing, and drying to obtain CuS@C / MoS2 composite materials. The method for preparing CuS@C / MoS2 composite materials provided by this invention has good electrical conductivity and catalytic activity, and is low in cost, simple in process, and has excellent hydrogen evolution performance.

Description

Technical Field

[0001] This invention relates to the field of electrocatalytic materials technology, and more specifically, to a method for preparing CuS@C / MoS2 composite materials. Background Technology

[0002] The escalating global energy crisis and environmental pollution necessitate the pursuit of economical, sustainable, and efficient energy sources. Hydrogen energy possesses a high calorific value (1.4 × 10⁻⁶). 8 With its high yield (J / kg) and environmentally friendly characteristics, hydrogen evolution reaction (Hg) is considered one of the most promising renewable green energy sources. In hydrogen production technology, the electrocatalytic hydrogen evolution reaction (ECH) has attracted significant attention due to its ability to produce high-purity hydrogen and drive green energy. The catalyst is the core of the electrocatalytic hydrogen production process, lowering the energy barrier of the electrocatalytic water splitting reaction. It is generally believed that an efficient catalyst should possess a near-thermally neutral H* absorption Gibbs free energy (i.e., ΔG). H* (≈0). Most catalysts designed for electrocatalytic water splitting to produce hydrogen are based on noble metals, such as platinum compounds, but their high cost and near-absence limit their widespread use. Therefore, it is imperative to research a low-cost, high-efficiency catalyst for the electrocatalytic hydrogen evolution reaction.

[0003] This invention provides a CuS@C / MoS2 composite material. A Cu2O@PDA precursor is prepared at room temperature using a simple method, followed by tube furnace heat treatment to transform the PDA into a carbon shell uniformly coating the cuprous oxide surface (Cu2O@C). Finally, molybdenum sulfide is grown on the Cu2O@C surface via a hydrothermal reaction to obtain the CuS@C / MoS2 composite material. The prepared composite catalyst exhibits good electrical conductivity and catalytic activity, and is low in cost, simple in preparation process, and short in production cycle, showing good application potential in the field of electrocatalytic hydrogen production. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing an electrocatalyst that has low cost and excellent electrocatalytic hydrogen evolution performance.

[0005] To achieve the above objectives, the present invention provides a method for preparing CuS@C / MoS2 composite materials, comprising the following steps:

[0006] Step S1: Dissolve copper sulfate and sodium citrate in a certain amount of deionized water to obtain solution A; add sodium hydroxide solution of a certain concentration dropwise to solution A while stirring to obtain solution B.

[0007] Step S2: After stirring solution B for a certain period of time, ascorbic acid solution of a certain concentration is added dropwise under the stirring condition of solution B to obtain solution C. After stirring and aging at room temperature for a certain period of time, the product is collected by centrifugation, washed several times with water and ethanol, and dried to obtain cuprous oxide.

[0008] Step S3: Disperse cuprous oxide in a certain amount of methanol to obtain a cuprous oxide-methanol solution. Add a certain concentration of dopamine (DA)-methanol solution dropwise to the cuprous oxide-methanol solution under stirring to obtain solution D. Stir solution D at an appropriate temperature for a certain time, centrifuge to collect the product, wash it several times with ethanol, and dry it to obtain polydopamine-coated cuprous oxide (Cu2O@PDA).

[0009] Step S4: Place Cu2O@PDA powder in a tube furnace and heat it in flowing argon (Ar) gas to obtain Cu2O@C powder;

[0010] Step S5: Dissolve Cu2O@C powder in a certain amount of deionized water to prepare Cu2O@C aqueous solution. Add a certain amount of ammonium molybdate and thiourea to the Cu2O@C aqueous solution to obtain solution E, and stir for a certain time. Transfer solution E to a reaction vessel, carry out hydrothermal reaction at a certain temperature for a period of time, cool to room temperature, collect the product by centrifugation, wash several times with ethanol and water, and dry to obtain CuS@C / MoS2 composite material.

[0011] Preferably, in step S1, the copper sulfate is copper sulfate pentahydrate, the molar ratio of copper sulfate to sodium citrate is 3:1-10:3, the deionization volume is 50-100 mL, the concentration of the sodium hydroxide solution is 0.15-2.4 mol / L, the dropping rate is 5-15 mL / min, and the stirring time is 5-30 min.

[0012] Preferably, in step S2, the concentration of the ascorbic acid solution is 0.01-0.1 mol / L, the dropping rate is 5-15 mL / min, and the aging time is 30-90 min.

[0013] Preferably, in step S3, the concentration of the dopamine (DA)-methanol solution is 0.01-0.05 mol / L, the dropping rate is 5-15 mL / min, the mass of the cuprous oxide is 200-400 mg, the volume of the methanol is 350-450 mL, the heating temperature is 55-65℃, and the heating time is 6-9 h.

[0014] Preferably, in step S4, the heating temperature is 600-900℃, the heating time is 1-3h, and the heating rate is 4-7℃ / min.

[0015] Preferably, in step S5, the ammonium molybdate is ammonium heptamolybdate tetrahydrate, the mass ratio of Cu2O@C, ammonium heptamolybdate tetrahydrate, and thiourea is (1.1-1.3):(20-30):(8-106), the hydrothermal temperature is 160-220℃, and the reaction time is 12-32h.

[0016] Preferably, in step S5, the CuS@C / MoS2 composite material is spherical in shape, and its surface includes 1T phase molybdenum sulfide and 2H phase molybdenum sulfide.

[0017] This invention uses copper sulfate, sodium citrate, methanol, sodium hydroxide solution, DA solution, and ascorbic acid solution as raw materials to prepare the precursor Cu₂O@PDA via a solution method. The presence of sodium citrate facilitates the formation of a complex between copper ions and citrate ions during the reaction, helping to control the formation rate of cuprous oxide and thus obtaining uniformly sized cubic cuprous oxide. A coordination-polymerization mechanism allows the catechol groups of dopamine to react with the Cu in Cu₂O. 1+ Coordination leads to strong adhesion of dopamine, resulting in its formation on the Cu2O surface. The alkaline nature of the methanol solvent, combined with increased temperature, triggers the polymerization of dopamine to yield polydopamine (PDA). The synthesized PDA contains catechol groups, which can further react with the Cu2O surface. 1+ Coordination further promotes the polymerization of polydopamine on Cu2O, resulting in the Cu2O@PDA sample. Calcination of Cu2O@PDA under an argon atmosphere yields carbon-shell-coated cuprous oxide (Cu2O@C), protecting the cuprous oxide, improving its durability and stability, and forming conductive channels with it to promote electron flow and increase current density. Using Cu2O@C as a precursor, ammonium molybdate and thiourea are synthesized via a one-step hydrothermal method to form elongated sheet-like molybdenum sulfide on spheres, rich in 1T-phase and 2H-phase molybdenum sulfide. The built-in electric field at the interface between the 1T-phase and 2H-phase molybdenum sulfide heterostructures enhances the conductivity and carrier transport capacity of the composite catalyst. By controlling the interlayer distance and reaction temperature during molybdenum sulfide synthesis, the directional transformation from 2H-phase to 1T-phase molybdenum sulfide can be better achieved, significantly increasing active sites and conductivity, accelerating hydrogen adsorption-dissociation, and obtaining better electrocatalytic hydrogen production performance. The CuS@C / MoS2 composite material provided by this invention has low cost, simple preparation process, short preparation cycle, and excellent electrocatalytic hydrogen evolution performance. It is non-toxic and harmless, and has good application prospects.

[0018] The present invention also provides a CuS@C / MoS2 composite material, which is prepared by the CuS@C / MoS2 composite material preparation method described above. Attached Figure Description

[0019] Figure 1 This is a schematic flowchart illustrating the preparation method of CuS@C / MoS2 composite material in an embodiment of the present invention.

[0020] Figure 2The X-ray diffraction patterns of the CuS@C / MoS2 composite material in Example 1, the molybdenum sulfide in Comparative Example 1, the copper sulfide / molybdenum sulfide composite catalyst in Comparative Example 2, and the CuS@PDA / MoS2 composite material in Comparative Example 3 are shown below.

[0021] Figure 3 The image shows the Raman spectrum of the CuS@C / MoS2 composite material in Example 1 of this invention.

[0022] Figure 4 shows scanning electron microscope images of the CuS@C / MoS2 composite material in Example 1 and the molybdenum sulfide catalyst in Comparative Example 1.

[0023] Figure 5 The polarization curves of the samples prepared in Example 1, Example 2, Comparative Example 1, Comparative Example 2 and Comparative Example 3 in 0.5M H2SO4 electrolyte are compared.

[0024] Figure 6 The image shows a comparison of the Tafel curves of the samples prepared in Example 1, Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3 in 0.5M H2SO4 electrolyte. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.

[0026] It should be noted that, unless otherwise specified, the features in the embodiments of this invention can be combined with each other. The terms "comprising," "including," "containing," and "having" are non-limiting, meaning that other steps and other components that do not affect the results can be added. The above terms cover the terms "composed of" and "substantially composed of." Unless otherwise specified, the materials, equipment, and reagents are commercially available.

[0027] This invention provides a method for preparing CuS@C / MoS2 composite materials, such as... Figure 1 As shown, it includes the following steps:

[0028] Step S1: Dissolve copper sulfate and sodium citrate together in a certain amount of deionized water to prepare the first mixed solution;

[0029] Step S1: Dissolve copper sulfate and sodium citrate in a certain amount of deionized water to obtain solution A; add sodium hydroxide solution of a certain concentration dropwise to solution A while stirring to obtain solution B.

[0030] Step S2: After stirring solution B for a certain period of time, ascorbic acid solution of a certain concentration is added dropwise under the stirring condition of solution B to obtain solution C. After stirring and aging at room temperature for a certain period of time, the product is collected by centrifugation, washed several times with water and ethanol, and dried to obtain cuprous oxide.

[0031] Step S3: Disperse cuprous oxide in a certain amount of methanol to obtain a cuprous oxide-methanol solution. Add a certain concentration of dopamine (DA)-methanol solution dropwise to the cuprous oxide-methanol solution under stirring to obtain solution D. Stir solution D at an appropriate temperature for a certain time, centrifuge to collect the product, wash it several times with ethanol, and dry it to obtain polydopamine-coated cuprous oxide (Cu2O@PDA).

[0032] Step S4: Place Cu2O@PDA powder in a tube furnace and heat it in flowing argon (Ar) gas to obtain Cu2O@C powder;

[0033] Step S5: Dissolve Cu2O@C powder in a certain amount of deionized water to prepare Cu2O@C aqueous solution. Add a certain amount of ammonium molybdate and thiourea to the Cu2O@C aqueous solution to obtain solution E, and stir for a certain time. Transfer solution E to a reaction vessel, carry out hydrothermal reaction at a certain temperature for a period of time, cool to room temperature, collect the product by centrifugation, wash several times with ethanol and water, and dry to obtain CuS@C / MoS2 composite material.

[0034] This invention uses copper sulfate, sodium citrate, methanol, sodium hydroxide solution, DA solution, and ascorbic acid solution as raw materials to prepare the precursor Cu₂O@PDA via a solution method. The presence of sodium citrate facilitates the formation of a complex between copper ions and citrate ions during the reaction, helping to control the formation rate of cuprous oxide and thus obtaining uniformly sized cubic cuprous oxide. A coordination-polymerization mechanism allows the catechol groups of dopamine to react with the Cu in Cu₂O. 1+ Coordination leads to strong adhesion of dopamine, resulting in its formation on the Cu2O surface. The alkaline nature of the methanol solvent, combined with increased temperature, triggers the polymerization of dopamine to yield polydopamine (PDA). The synthesized PDA contains catechol groups, which can further react with the Cu2O surface. 1+Coordination further promotes the polymerization of polydopamine on Cu2O, resulting in the Cu2O@PDA sample. Calcination of Cu2O@PDA under an argon atmosphere yields carbon-shell-coated cuprous oxide (Cu2O@C), protecting the cuprous oxide, improving its durability and stability, and forming conductive channels with it to promote electron flow and increase current density. Using Cu2O@C as a precursor, ammonium molybdate and thiourea are synthesized via a one-step hydrothermal method to form elongated sheet-like molybdenum sulfide on spheres, rich in 1T-phase and 2H-phase molybdenum sulfide. The built-in electric field at the interface between the 1T-phase and 2H-phase molybdenum sulfide heterostructures enhances the conductivity and carrier transport capacity of the composite catalyst. By controlling the interlayer distance and reaction temperature during molybdenum sulfide synthesis, the directional transformation from 2H-phase to 1T-phase molybdenum sulfide can be better achieved, significantly increasing active sites and conductivity, accelerating hydrogen adsorption-dissociation, and obtaining better HER performance. The CuS@C / MoS2 composite material provided by this invention has low cost, simple preparation process, short preparation cycle, and excellent electrocatalytic hydrogen evolution performance. It is non-toxic and harmless, and has good application prospects.

[0035] In step S1, the copper sulfate is copper sulfate pentahydrate, the molar ratio of copper sulfate to sodium citrate is 3:1-10:3, the deionization volume is 50-100 mL, the concentration of the sodium hydroxide solution is 0.15-2.4 mol / L, the dropping rate is 5-15 mL / min, and the stirring time is 5-30 min.

[0036] For example, anhydrous copper sulfate is used. Sodium citrate (10-13):1 mmol is dissolved in 50-100 mL of deionized water and stirred for 5-30 min to obtain solution A. Sodium hydroxide solution with a concentration of 0.15-2.4 mol / L is added dropwise to obtain solution B while solution A is being stirred.

[0037] In step S2, the concentration of the ascorbic acid solution is 0.01-0.1 mol / L, the dropping rate is 5 mL / min, the stirring time is 3-5 min, and the aging time is 30-90 min.

[0038] For example, after stirring solution B for 5-30 min, ascorbic acid solution with a concentration of 0.01-0.1 mol / L is added dropwise to solution B to obtain solution C at a dropping rate of 5 mL / min. After stirring for 3-5 min, the solution is aged at room temperature for 30-90 min. The precipitate is then separated, washed several times with ethanol and deionized water to remove impurities, and dried in an oven at 60℃ for 12 h. After grinding, cuprous oxide is obtained.

[0039] In step S3, the mass of cuprous oxide is 200-400 mg, the volume of methanol is 350-450 mL, the concentration of dopamine (DA)-methanol solution is 0.01-0.05 mol / L, the dropping rate is 5-15 mL / min, the heating temperature is 55-65℃, and the heating time is 6-9 h.

[0040] For example, 200-400 mg of cuprous oxide was dispersed in 350-450 mL of methanol, and then a dopamine (DA)-methanol solution with a concentration of 0.01-0.05 mol / L was added dropwise to obtain solution D. Solution D was stirred at 60 °C for 7 h. The product was collected by centrifugation for 3 min (10000 rpm), washed several times with methanol, and dried at 65 °C for 8 h to obtain polydopamine-coated cuprous oxide (Cu2O@PDA).

[0041] In step S4, the heating temperature is 600-900℃, the heating time is 1-3h, and the heating rate is 4-7℃ / min.

[0042] For example, Cu2O@PDA powder is placed in a tube furnace and heated to 600-900°C for 1-3 hours in flowing Ar at a heating rate of 4-7°C / min to prepare Cu2O@C, thereby obtaining the Cu2O@C precursor.

[0043] In step S5, the ammonium molybdate is ammonium heptamolybdate tetrahydrate, the mass ratio of Cu2O@C, ammonium heptamolybdate tetrahydrate, and thiourea is (1.1-1.3):(20-30):(8-106), the hydrothermal temperature is 160-220℃, and the reaction time is 12-32h.

[0044] For example, ammonium molybdate is ammonium heptamolybdate tetrahydrate. A mixed reaction is obtained by mixing 1.1-1.3 parts of Cu₂O@C catalyst with 28-32 mL of deionized water, followed by 20-30 parts of ammonium heptamolybdate tetrahydrate and 8-50 parts of thiourea. The mixture is stirred for 5-30 min to obtain solution E. Solution E is then transferred to a reaction vessel and reacted at 160-220°C for 12-32 h.

[0045] By controlling the reaction temperature within the range of 160-220℃ and controlling the interlayer distance during the synthesis of molybdenum sulfide, the directional transformation from 2H phase molybdenum sulfide to 1T phase molybdenum sulfide can be better achieved, thereby significantly increasing the active sites and conductivity, accelerating the adsorption-dissociation of hydrogen, and obtaining better electrocatalytic hydrogen production performance.

[0046] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed according to the conditions recommended by the manufacturer.

[0047] Example 1

[0048] 1.1 Dissolve 1.5 mmol of anhydrous copper sulfate and 0.5 mmol of sodium citrate in 80 mL of deionized water and stir for 15 min to obtain solution A. Under stirring conditions, add 20 mL of 1.25 M NaOH solution dropwise to solution A and stir for 15 min to obtain solution B.

[0049] 1.2 Add 50 mL of 0.03 M ascorbic acid solution to solution B, stir for 3 min to obtain solution C, and then age at room temperature for 1 h to form a brick red precipitate. Collect the brick red precipitate, wash it repeatedly with water and ethanol, dry it, and grind it to obtain cubic cuprous oxide.

[0050] 1.3. Disperse 300 mg of cuprous oxide in 375 mL of methanol, then add 75 mL of 20 mM DA methanol solution to obtain solution D. Stir solution D at 60 °C for 7 h. Collect the product by centrifugation for 3 min (10000 rpm), wash several times with ethanol, and dry at 65 °C for 8 h to obtain polydopamine-coated cuprous oxide (Cu2O@PDA).

[0051] 1.4. Cu2O@PDA powder was placed in a tube furnace and heated to 750℃ for 2 hours in flowing Ar at a heating rate of 5℃ / min to prepare Cu2O@C. This yielded a Cu2O@C catalyst prepared using Cu2O@C as a precursor.

[0052] 1.5. Mix 60 mg of Cu2O@C and 28 mL of deionized water to obtain a mixed aqueous solution. Then, add 1.02 g of ammonium heptamolybdate tetrahydrate and 0.4 g of thiourea to the mixed aqueous solution and stir to obtain solution E. Transfer solution E to a stainless steel reactor lined with Teflon and react at 220 °C for 27 h. After cooling to room temperature, wash three times each with ethanol and water, and vacuum dry at 60 °C for 12 h to obtain the CuS@C / MoS2 composite catalyst.

[0053] Example 2

[0054] 2.1 Dissolve 1.5 mmol of anhydrous copper sulfate and 0.5 mmol of sodium citrate in 80 mL of deionized water and stir for 15 min to obtain solution A. Under stirring conditions, add 20 mL of 1.25 M NaOH solution dropwise to solution A and stir for 15 min to obtain solution B.

[0055] 2.2 Add 50 mL of 0.03 M ascorbic acid solution to solution B, stir for 3 min to obtain solution C, and then age at room temperature for 1 h to form a brick red precipitate. Collect the brick red precipitate, wash it repeatedly with water and ethanol, dry it, and grind it to obtain cubic cuprous oxide.

[0056] 2.3. 300 mg of cuprous oxide was dispersed in 375 mL of methanol, and then 75 mL of 20 mM DDA methanol solution was added to obtain solution D. Solution D was stirred at 60 °C for 7 h. The product was collected by centrifugation for 3 min (10000 rpm), washed several times with ethanol, and dried at 65 °C for 8 h to obtain polydopamine-coated cuprous oxide (Cu2O@PDA).

[0057] 2.4. Cu2O@PDA powder was placed in a tube furnace and heated to 750℃ for 2 hours in flowing Ar at a heating rate of 5℃ / min to prepare Cu2O@C. This yielded a Cu2O@C catalyst prepared using Cu2O@C as a precursor.

[0058] 2.5. Mix 50 mg of Cu2O@C and 28 mL of deionized water to obtain a mixed aqueous solution. Then, add 1.02 g of ammonium heptamolybdate tetrahydrate and 0.4 g of thiourea to the mixed aqueous solution and stir to obtain solution E. Transfer solution E to a stainless steel reactor lined with Teflon and react at 220 °C for 27 h. After cooling to room temperature, wash three times each with ethanol and water, and vacuum dry at 60 °C for 12 h to obtain the CuS@C / MoS2 composite catalyst.

[0059] Example 3

[0060] 3.1 Dissolve 1.5 mmol of anhydrous copper sulfate and 0.5 mmol of sodium citrate in 80 mL of deionized water and stir for 15 min to obtain solution A. Under stirring conditions, add 20 mL of 1.25 M NaOH solution dropwise to solution A and stir for 15 min to obtain solution B.

[0061] 3.2 Add 50 mL of 0.03 M ascorbic acid solution to solution B, stir for 3 min to obtain solution C, and then age at room temperature for 1 h to form a brick red precipitate. Collect the brick red precipitate, wash it repeatedly with water and ethanol, dry it, and grind it to obtain cubic cuprous oxide.

[0062] 3.3. Disperse 300 mg of cuprous oxide in 375 mL of methanol, then add 75 mL of 40 mM DDA methanol solution to obtain solution D. Stir solution D at 60 °C for 7 h. Collect the product by centrifugation for 3 min (10000 rpm), wash several times with ethanol, and dry at 65 °C for 8 h to obtain polydopamine-coated cuprous oxide (Cu2O@PDA).

[0063] 3.4. Cu2O@PDA powder was placed in a tube furnace and heated to 750℃ for 2 hours in flowing Ar at a heating rate of 5℃ / min to prepare Cu2O@C. This yielded a Cu2O@C catalyst prepared using Cu2O@C as a precursor.

[0064] 3.5. Mix 60 mg of Cu2O@C and 28 mL of deionized water to obtain a mixed aqueous solution. Then, add 1.02 g of ammonium heptamolybdate tetrahydrate and 0.4 g of thiourea to the mixed aqueous solution and stir to obtain solution E. Transfer solution E to a stainless steel reactor lined with Teflon and react at 220 °C for 27 h. After cooling to room temperature, wash three times each with ethanol and water, and vacuum dry at 60 °C for 12 h to obtain the CuS@C / MoS2 composite catalyst.

[0065] Example 4

[0066] 4.1 Dissolve 1.65 mmol of anhydrous copper sulfate and 0.4 mmol of sodium citrate in 100 mL of deionized water and stir for 15 min to obtain solution A. Under stirring conditions, add 20 mL of 1.05 M NaOH solution dropwise to solution A and stir for 15 min to obtain solution B.

[0067] 4.2 Add 40 mL of 0.05 M ascorbic acid solution to solution B, stir for 3 min to obtain solution C, and then age at room temperature for 1 h to form a brick red precipitate. Collect the brick red precipitate, wash it repeatedly with water and ethanol, dry it, and grind it to obtain cubic cuprous oxide.

[0068] 4.3. Disperse 300 mg of cuprous oxide in 400 mL of methanol, then add 75 mL of 20 mM DDA methanol solution to obtain solution D. Stir solution D at 65 °C for 7 h. Collect the product by centrifugation for 3 min (10000 rpm), wash several times with ethanol, and dry at 65 °C for 8 h to obtain polydopamine-coated cuprous oxide (Cu2O@PDA).

[0069] 4.4. Cu2O@PDA powder was placed in a tube furnace and heated to 850℃ for 2 hours in flowing Ar at a heating rate of 4℃ / min to prepare Cu2O@C. This yielded a Cu2O@C catalyst prepared using Cu2O@C as a precursor.

[0070] 4.5. Mix 70 mg of Cu2O@C and 28 mL of deionized water to obtain a mixed aqueous solution. Then, add 1.02 g of ammonium heptamolybdate tetrahydrate and 0.4 g of thiourea to the mixed aqueous solution and stir to obtain solution E. Transfer solution E to a stainless steel reactor lined with Teflon and react at 220 °C for 27 h. After cooling to room temperature, wash three times each with ethanol and water, and vacuum dry at 60 °C for 12 h to obtain the CuS@C / MoS2 composite catalyst.

[0071] Example 5

[0072] 5.1 Dissolve 1.65 mmol of anhydrous copper sulfate and 0.5 mmol of sodium citrate in 80 mL of deionized water and stir for 15 min to obtain solution A. Under stirring conditions, add 30 mL of 1.25 M NaOH solution dropwise to solution A and stir for 15 min to obtain solution B.

[0073] 5.2 Add 80 mL of 0.03 M ascorbic acid solution to solution B, stir for 3 min to obtain solution C, and then age at room temperature for 1 h to form a brick red precipitate. Collect the brick red precipitate, wash it repeatedly with water and ethanol, dry it, and grind it to obtain cubic cuprous oxide.

[0074] 5.3. 275 mg of cuprous oxide was dispersed in 350 mL of methanol, and then 100 mL of 20 mM DDA methanol solution was added to obtain solution D. Solution D was stirred at 65 °C for 7 h. The product was collected by centrifugation for 3 min (10000 rpm), washed several times with ethanol, and dried at 65 °C for 8 h to obtain polydopamine-coated cuprous oxide (Cu2O@PDA).

[0075] 5.4. Cu2O@PDA powder was placed in a tube furnace and heated to 750℃ for 2 hours in flowing Ar at a heating rate of 4℃ / min to prepare Cu2O@C. This yielded a Cu2O@C catalyst prepared using Cu2O@C as a precursor.

[0076] 5.5. Mix 60 mg of Cu2O@C and 28 mL of deionized water to obtain a mixed aqueous solution. Then, add 1.02 g of ammonium heptamolybdate tetrahydrate and 0.4 g of thiourea to the mixed aqueous solution and stir to obtain solution E. Transfer solution E to a stainless steel reactor lined with Teflon and react at 220 °C for 24 h. After cooling to room temperature, wash three times each with ethanol and water, and vacuum dry at 60 °C for 12 h to obtain the CuS@C / MoS2 composite catalyst.

[0077] Comparative Example 1

[0078] 1.1 Dissolve 1.02 g of ammonium heptamolybdate tetrahydrate in 28 mL of deionized water, then add 0.4 g of thiourea and stir until the solution is clear. Transfer the solution to a stainless steel reactor lined with Teflon and react at 220 °C for 27 h. Cool to room temperature, wash three times each with ethanol and water, and dry in a vacuum drying oven at 60 °C for 12 h to obtain flower-shaped molybdenum sulfide.

[0079] Comparative Example 2

[0080] 2.1 Dissolve 1.5 mmol of anhydrous copper sulfate and 0.5 mmol of sodium citrate in 80 mL of deionized water and stir for 15 min to obtain solution A. Under stirring conditions, add 20 mL of 1.25 M NaOH solution dropwise to solution A and stir for 15 min to obtain solution B.

[0081] 2.2 Add 50 mL of 0.03 M ascorbic acid solution to solution B, stir for 3 min to obtain solution C, and then age at room temperature for 1 h to form a brick red precipitate. Collect the brick red precipitate, wash it repeatedly with water and ethanol, dry it, and grind it to obtain cubic cuprous oxide.

[0082] 2.3. Mix 60 mg of Cu2O and 28 mL of deionized water to obtain a mixed aqueous solution. Then add 1.02 g of ammonium heptamolybdate tetrahydrate and 0.4 g of thiourea to the mixed aqueous solution and stir to obtain solution D.

[0083] 2.5. The D solution was transferred to a stainless steel reactor lined with Teflon and reacted at 220°C for 27 h. After cooling to room temperature, the solution was washed three times each with ethanol and water and then vacuum dried at 60°C for 12 h to obtain the molybdenum sulfide / copper sulfide composite catalyst.

[0084] Comparative Example 3

[0085] 3.1 Dissolve 1.5 mmol of anhydrous copper sulfate and 0.5 mmol of sodium citrate in 80 mL of deionized water and stir for 15 min to obtain solution A. Under stirring conditions, add 20 mL of 1.25 M NaOH solution to solution A and stir for 15 min to obtain solution B.

[0086] 3.2 Add 50 mL of 0.03 M ascorbic acid solution to solution B, stir for 3 min to obtain solution C, and then age at room temperature for 1 h to form a brick red precipitate. Collect the brick red precipitate, wash it repeatedly with water and ethanol, dry it, and grind it to obtain cubic cuprous oxide.

[0087] 3.3. 300 mg of cuprous oxide was dispersed in 375 mL of methanol, and then 75 mL of 20 mM DDA methanol solution was added to obtain solution D. Solution D was then stirred at 60 °C for 7 h. The product was collected by centrifugation for 3 min (10000 rpm), washed several times with ethanol, and dried at 65 °C for 8 h to obtain polydopamine-coated cuprous oxide (Cu2O@PDA).

[0088] 3.4. Mix 60 mg of Cu2O@PDA and 28 mL of deionized water to obtain an aqueous solution of Cu2O@PDA. Then, add 1.02 g of ammonium heptamolybdate tetrahydrate and 0.4 g of thiourea to the Cu2O@PDA aqueous solution and stir to form a fifth mixed solution. Transfer the fifth mixed solution to a stainless steel reactor lined with Teflon and react at 220 °C for 27 h. After cooling to room temperature, wash three times each with ethanol and water, and vacuum dry at 60 °C for 12 h to obtain the CuS@PDA / MoS2 composite catalyst.

[0089] Experimental Example 1

[0090] The CuS@C / MoS2 composite catalyst obtained in Example 1 was subjected to X-ray diffraction analysis and observed by scanning electron microscopy.

[0091] Figure 2 The X-ray diffraction patterns are shown for the CuS@C / MoS2 composite catalyst in Example 1, the molybdenum sulfide catalyst in Comparative Example 1, the copper sulfide / molybdenum sulfide composite catalyst in Comparative Example 2, and the CuS@PDA / MoS2 composite catalyst in Comparative Example 3. Figure 2 It can be seen that the X-ray diffraction peaks appearing in Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 all correspond to the standard molybdenum sulfide diffraction peaks and standard copper sulfide diffraction peaks, indicating that the composite catalysts prepared in Example 1, Comparative Example 2 and Comparative Example 3 contain both molybdenum sulfide and copper sulfide.

[0092] Figure 3This is the Raman spectrum of the CuS@C / MoS2 composite material in Example 1 of the present invention. Figure 5 J1, J2, and E phases of 1T phase molybdenum sulfide can be observed. 1g The characteristic peaks of the J3 vibration mode.

[0093] Figure 4 is a scanning electron microscope image of the CuS@C / MoS2 composite catalyst in Example 1. Figure 3 It can be seen that its microscopic morphology is cubic flower ball-shaped.

[0094] Figure 4 shows scanning electron microscope (SEM) images of the CuS@C / MoS2 composite material in Example 1 and molybdenum sulfide in Comparative Example 1. Figure 3 (a) and Figure 3 (b) shows scanning electron microscope (SEM) images of molybdenum sulfide in Comparative Example 1 and the CuS@C / MoS2 composite material obtained in Example 1, respectively. Figure 3 Analysis revealed that, compared to molybdenum sulfide in Comparative Example 1, the molybdenum sulfide growth in the CuS@C / MoS2 composite material in Example 1 was more uniform and denser, with more active sites exposed at the edges of the molybdenum sulfide, thereby improving catalytic activity.

[0095] Experiment Example 2

[0096] The electrolytic hydrogen evolution reaction performance of the samples prepared in Examples 1, 2, 3, Comparative Examples 1, 2, and 3 was tested. Specifically, the materials prepared in Examples 1, 2, 3, 1, 2, and 3 were used as working electrodes for the electrocatalytic hydrogen evolution reaction. A saturated calomel electrode was used as the reference electrode, and a platinum electrode as the counter electrode, forming a three-electrode system. This system was connected to an electrochemical workstation and tested in a 0.5 mol / L H₂SO₄ electrolyte. HER polarization curves were performed on the samples at a scan rate of 50 mV / s.

[0097] Test results are as follows Figure 5 and Figure 6 As shown.

[0098] Figure 5 This is a comparison of the polarization curves of the samples prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3 in 0.5 mol / L H2SO4 electrolyte. Figure 5 As can be seen from the data, the CuS@C / MoS2 composite material prepared in Example 1 exhibits good performance at a current density of 10 mA·cm⁻¹. -2 The overpotential of the sample was 39.5 mV, while that of the molybdenum sulfide prepared in Comparative Example 1 was 39.5 mV at a current density of 10 mA·cm⁻¹. -2The overpotential was 265.5 mV, indicating that the CuS@C / MoS2 composite material prepared in Example 1 has a smaller overpotential and can effectively reduce the activation energy of the reaction.

[0099] Figure 6 This is a comparison of Tafel curves in 0.5 mol / L H2SO4 electrolyte for samples prepared in Examples 1, 2, 3, Comparative Examples 1, 2, and 3. Figure 6 As can be seen, Example 1 has a smaller Tafel slope, indicating that it can obtain a larger current under a smaller potential. The CuS@C / MoS2 composite material prepared in Example 1 is more conducive to hydrogen evolution.

[0100] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for preparing CuS@C / MoS2 composite material, characterized in that, Includes the following steps: Step S1: Dissolve copper sulfate and sodium citrate in a certain amount of deionized water to obtain solution A; add sodium hydroxide solution of a certain concentration dropwise to solution A while stirring to obtain solution B. Step S2: After stirring solution B for a certain period of time, ascorbic acid solution of a certain concentration is added dropwise under the stirring condition of solution B to obtain solution C. After stirring and aging at room temperature for a certain period of time, the product is collected by centrifugation, washed several times with water and ethanol, and dried to obtain cuprous oxide. Step S3: Disperse 200-400 mg of cuprous oxide in 350-450 mL of methanol to obtain a cuprous oxide-methanol solution. Add a 0.01-0.05 mol / L dopamine DA-methanol solution to the cuprous oxide-methanol solution under stirring at a dropping rate of 5-15 mL / min to obtain solution D. After stirring the D solution at 55-65℃ for 6-9 hours, the product was collected by centrifugation, washed several times with ethanol, and dried to obtain polydopamine-coated cuprous oxide Cu2O@PDA. Step S4: Place Cu2O@PDA powder in a tube furnace and heat it in flowing argon gas at 600-900℃ with a heating rate of 4-7℃ / min for 1-3 hours to obtain Cu2O@C powder. Step S5: Dissolve Cu2O@C powder in a certain amount of deionized water to prepare Cu2O@C aqueous solution. Add a certain amount of ammonium heptamolybdate tetrahydrate and thiourea to the Cu2O@C aqueous solution to obtain solution E. The mass ratio of Cu2O@C, ammonium heptamolybdate tetrahydrate and thiourea is 1.1-1.3:20-30:8-106, and stir for a certain time. Transfer solution E to a reaction vessel and carry out hydrothermal reaction at 160-220℃ for 12-32 hours. After cooling to room temperature, collect the product by centrifugation, wash several times with ethanol and water, and dry to obtain CuS@C / MoS2 composite material.

2. The method for preparing the CuS@C / MoS2 composite material according to claim 1, characterized in that, In step S1, the copper sulfate is copper sulfate pentahydrate, the molar ratio of copper sulfate to sodium citrate is 3:1-10:3, the deionization volume is 50-100 mL, the concentration of the sodium hydroxide solution is 0.15-2.4 mol / L, the dropping rate is 5-15 mL / min, and the stirring time is 5-30 min.

3. The method for preparing the CuS@C / MoS2 composite material according to claim 1, characterized in that, In step S2, the concentration of the ascorbic acid solution is 0.01-0.1 mol / L, the dropping rate is 5-15 mL / min, the stirring time is 3-5 min, and the aging time is 30-90 min.

4. A CuS@C / MoS2 composite material, characterized in that, The CuS@C / MoS2 composite material was prepared using the method described in any one of claims 1-3.

5. The CuS@C / MoS2 composite material according to claim 4, characterized in that, The CuS@C / MoS2 composite material is spherical in shape, and its surface includes 1T phase molybdenum sulfide and 2H phase molybdenum sulfide.

Images