Molybdenum sulfide / copper sulfide composite catalyst, working electrode and preparation method thereof

Abstract

The application provides a molybdenum sulfide / copper sulfide composite catalyst, a working electrode and a preparation method thereof, and belongs to the technical field of electrocatalytic materials.The preparation method comprises the following steps: dissolving copper sulfate and sodium citrate in deionized water to obtain a solution A; adding a sodium hydroxide solution into the solution A to obtain a solution B; adding an ascorbic acid solution dropwise into the solution B, and aging at room temperature to form a brick red precipitate; separating the brick red precipitate to obtain cuprous oxide in a cubic shape; mixing the cuprous oxide in the cubic shape with deionized water to obtain a mixed solution, and then adding ammonium molybdate and thiourea to obtain a solution C; transferring the solution C into a reaction kettle, cooling to room temperature after heating reaction, and obtaining the molybdenum sulfide / copper sulfide composite catalyst.The molybdenum sulfide / copper sulfide composite catalyst provided by the application has the advantages of low cost, simple preparation process, short preparation period, excellent electrocatalytic hydrogen evolution performance, non-toxicity and harmlessness, and good application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalytic materials, and in particular to a molybdenum sulfide / copper sulfide composite catalyst, a working electrode and a preparation method thereof. Background Art

[0002] The excessive use of traditional fossil fuels can lead to problems such as the greenhouse effect, ecological damage, and energy depletion. Therefore, the development of efficient, clean, and renewable energy has become a trend. Among them, hydrogen, which has the characteristics of high energy density, zero carbon content, non-toxicity, and pollution-free combustion, has broad prospects in replacing traditional fossil fuels as a renewable clean energy. The electrolysis of water to produce hydrogen reaction (HER) has the advantages of a wide range of raw materials, high efficiency, only hydrogen and oxygen as products, no other by-products, and the electricity used can be converted from wind energy, solar energy, and other renewable energy sources. However, the electrolysis of water to produce hydrogen reaction has a large overpotential, that is, the electricity consumption is large, which limits the practical application of large-scale electrolysis of water to produce hydrogen.

[0003] To reduce the energy consumption of the hydrogen evolution reaction (HER) from water electrolysis, catalysts can be used to lower the activation energy barrier of the water-splitting reaction, thereby improving the reaction's energy efficiency. Currently, the precious metal platinum (Pt) and Pt-based composites are the most efficient electrocatalysts for HERR. However, the low Earth reserves and high cost of Pt severely limit its practical application as an electrocatalyst. Summary of the Invention

[0004] The problem solved by the present invention is to provide a method for preparing an electrocatalyst with low cost and excellent electrocatalytic hydrogen evolution performance.

[0005] To solve the above problems, the present invention provides a method for preparing a molybdenum sulfide / copper sulfide composite catalyst, comprising the following steps:

[0006] Step S1, dissolving copper sulfate and sodium citrate in deionized water to obtain solution A;

[0007] Step S2, adding sodium hydroxide solution to the solution A under stirring to obtain solution B;

[0008] Step S3, adding ascorbic acid solution dropwise to the solution B, stirring and mixing, and aging at room temperature to form a brick-red precipitate;

[0009] Step S4, separating the brick-red precipitate, washing, drying, and grinding to obtain cubic cuprous oxide;

[0010] Step S5, mixing the cubic cuprous oxide with deionized water to obtain a mixed solution, and then adding ammonium molybdate and thiourea to form a brick-red solution to obtain solution C;

[0011] Step S6: transferring the solution C to a reactor, heating for reaction, cooling to room temperature, washing, and drying to obtain a molybdenum sulfide / copper sulfide composite catalyst.

[0012] Preferably, in step S1, the molar ratio of the copper sulfate to the sodium citrate is 15:1-5:9.

[0013] Preferably, in step S2, the concentration of the sodium hydroxide solution is 0.5-2 mol / L.

[0014] Preferably, in step S3, the concentration of the ascorbic acid solution is 0.01-0.3 mol / L, the dropping speed is 5 mL / min, and the aging time is 1-5 h.

[0015] Preferably, in step S5, the ammonium molybdate is ammonium heptamolybdate tetrahydrate, and the mass ratio of the cubic cuprous oxide, the ammonium heptamolybdate tetrahydrate and the thiourea is (1.1-1.3):(20-30):(8-106).

[0016] Preferably, in step S6, the solution C is transferred to a reactor and reacted at a temperature of 160-230° C. for 12-30 hours.

[0017] The present invention uses copper sulfate, sodium citrate, sodium hydroxide solution and ascorbic acid solution as raw materials to prepare cuprous oxide, a precursor of copper sulfide, through a solution process. Due to the presence of sodium citrate, copper ions form a complex with citrate during the reaction, which helps to slow down the generation rate of cuprous oxide and make the cuprous oxide grow at a uniform rate, thereby obtaining cuprous oxide with good morphology. The cuprous oxide is in the shape of a cube. The cube-shaped cuprous oxide is then reacted with ammonium molybdate and thiourea through a one-step hydrothermal process to form cubic flower-shaped molybdenum sulfide / copper sulfide. The molybdenum sulfide is rich in 1T phase. The built-in electric field at the interface of the 1T phase molybdenum sulfide and the molybdenum sulfide / copper sulfide heterostructure can improve the conductivity and carrier transport capacity of the composite catalyst, thereby improving its electrocatalytic performance. The molybdenum sulfide / copper sulfide composite catalyst provided by the present invention has low cost, simple preparation process, short preparation cycle, excellent electrocatalytic hydrogen evolution performance, is non-toxic and harmless, and has good application prospects.

[0018] The present invention also provides a molybdenum sulfide / copper sulfide composite catalyst, which is prepared by the above-mentioned preparation method of the molybdenum sulfide / copper sulfide composite catalyst.

[0019] Preferably, the molybdenum sulfide / copper sulfide is in the shape of a cubic flower ball, and the molybdenum sulfide / copper sulfide comprises 1T phase molybdenum sulfide.

[0020] The beneficial effects of the molybdenum sulfide / copper sulfide composite catalyst provided by the present invention compared with the prior art are the same as the preparation method of the molybdenum sulfide / copper sulfide composite catalyst, which will not be repeated here.

[0021] The present invention also provides a working electrode for electrocatalytic hydrogen evolution reaction, which is prepared using the above-mentioned molybdenum sulfide / copper sulfide composite catalyst.

[0022] The beneficial effects of the working electrode for electrocatalytic hydrogen evolution reaction provided by the present invention over the prior art are the same as the preparation method of the molybdenum sulfide / copper sulfide composite catalyst, which will not be described in detail here.

[0023] The present invention also provides a method for preparing a working electrode for an electrocatalytic hydrogen evolution reaction, which is used to prepare the working electrode for the electrocatalytic hydrogen evolution reaction as described above, comprising the following steps:

[0024] Step T1, mixing 20 mg of the molybdenum sulfide / copper sulfide composite catalyst and 10 mg of carbon black, grinding the mixture, washing, drying, and grinding the mixture again to obtain a pretreated catalyst;

[0025] Step T2, adding 5 mg of the pretreated catalyst to a mixed solution of ethanol and water, and ultrasonically dispersing the mixture to form a catalyst solution;

[0026] Step T3: drop 5 μL of the catalyst solution onto the surface of the glassy carbon electrode, add 5 μL of naphthol after drying, and dry again to obtain a working electrode for the electrocatalytic hydrogen evolution reaction.

[0027] The method for preparing the working electrode for the electrocatalytic hydrogen evolution reaction provided by the present invention has the same beneficial effects as the method for preparing the molybdenum sulfide / copper sulfide composite catalyst compared to the prior art, and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the process for preparing a molybdenum sulfide / copper sulfide composite catalyst according to an embodiment of the present invention;

[0029] Figure 2 Schematic diagram of a process for preparing a working electrode for electrocatalytic hydrogen evolution reaction according to an embodiment of the present invention;

[0030] Figure 3 is the X-ray diffraction pattern of the molybdenum sulfide / copper sulfide composite catalyst in Example 1 of the present invention;

[0031] Figure 4 This is a scanning electron microscope image of the molybdenum sulfide / copper sulfide composite catalyst in Example 1 of the present invention;

[0032] Figure 5 This is a transmission electron micrograph of the molybdenum sulfide / copper sulfide composite catalyst in Example 1 of the present invention;

[0033] Figure 6 Comparison of polarization curves of samples prepared in Example 1 and Comparative Example 1 in 0.5M H2SO4 electrolyte;

[0034] Figure 7 A comparison of Tafel curves of the samples prepared in Example 1 and Comparative Example 1 in 0.5M H2SO4 electrolyte;

[0035] Figure 8 Polarization curve analysis diagram of the samples prepared in Example 1 and Example 2 of the present invention in 0.5M H2SO4 electrolyte;

[0036] Figure 9 This is a Tafel plot analysis diagram of the samples prepared in Example 1 and Example 2 of the present invention in 0.5M H2SO4 electrolyte. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below.

[0038] It should be noted that, unless otherwise specified, the features of the embodiments of the present invention may be combined with each other. The terms "comprising," "including," "containing," and "having" are non-restrictive and may include other steps and other components that do not affect the results. The above terms encompass the terms "consisting of" and "consisting essentially of." Unless otherwise specified, materials, equipment, and reagents were commercially available.

[0039] The present invention provides a method for preparing a molybdenum sulfide / copper sulfide composite catalyst. Figure 1 As shown, the following steps are included:

[0040] Step S1, dissolving copper sulfate and sodium citrate in deionized water to obtain solution A;

[0041] Step S2, adding sodium hydroxide solution to the solution A under stirring to obtain solution B;

[0042] Step S3, adding ascorbic acid solution dropwise to the solution B, stirring and mixing, and aging at room temperature to form a brick-red precipitate;

[0043] Step S4, separating the brick-red precipitate, washing, drying, and grinding to obtain cubic cuprous oxide;

[0044] Step S5, mixing the cubic cuprous oxide with deionized water to obtain a mixed solution, and then adding ammonium molybdate and thiourea to form a brick-red solution to obtain solution C;

[0045] Step S6: transferring the solution C to a reactor, heating for reaction, cooling to room temperature, washing, and drying to obtain a molybdenum sulfide / copper sulfide composite catalyst.

[0046] The embodiment of the present invention uses copper sulfate, sodium citrate, sodium hydroxide solution and ascorbic acid solution as raw materials to prepare cuprous oxide, a precursor of copper sulfide, by a solution method. Due to the presence of sodium citrate, copper ions form a complex with citrate during the reaction, which helps to slow down the generation rate of cuprous oxide and make cuprous oxide grow at a uniform rate, thereby obtaining cuprous oxide with good morphology. The cuprous oxide is in the shape of a cube. The cubic cuprous oxide is then reacted with ammonium molybdate and thiourea by a one-step hydrothermal method to form a cubic flower-shaped molybdenum sulfide / copper sulfide, which is rich in 1T phase molybdenum sulfide. The built-in electric field at the interface of the 1T phase molybdenum sulfide and molybdenum sulfide / copper sulfide heterostructure can improve the conductivity and carrier transport capacity of the composite catalyst, thereby improving its electrocatalytic performance. The molybdenum sulfide / copper sulfide composite catalyst provided by the embodiment of the present invention has low cost, simple preparation process, short preparation cycle, excellent electrocatalytic hydrogen evolution performance, is non-toxic and harmless, and has good application prospects.

[0047] In step S1, the molar ratio of the copper sulfate to the sodium citrate is 15:1-5:9. The presence of sodium citrate in solution A can narrow the particle size distribution of cuprous oxide (Cu2O), thereby forming cuprous oxide with regular morphology. This is mainly due to the fact that in the subsequent reaction process, Cu 2+ It can form a complex with citrate ions to slow down the growth rate of Cu2O, so that the Cu2O crystals grow at a uniform rate, thus obtaining Cu2O with good morphology.

[0048] Here, the molar ratio refers to the molar ratio.

[0049] For example, the copper sulfate is anhydrous copper sulfate, and 0.5-3 mmol and 0.2-0.9 mmol of sodium citrate are dissolved in 80 mL of deionized water, and stirred for 15 minutes to fully mix to obtain a solution A containing copper sulfate and sodium citrate.

[0050] In step S2, the concentration of the sodium hydroxide solution is 0.5-2 mol / L. After the sodium hydroxide solution is mixed with solution A, the sodium hydroxide can react with copper sulfate to generate copper hydroxide. Due to the presence of sodium citrate, the reaction rate is slow.

[0051] For example, 20 mL of a sodium hydroxide solution having a concentration of 0.5-2 mol / L is mixed with the aforementioned solution A to form solution B.

[0052] In step S3, the concentration of the ascorbic acid solution is 0.01-0.3 mol / L, the dropping speed is 5 mL / min, and the aging time is 1-5 h.

[0053] Ascorbic acid, as a reducing agent, can react with copper hydroxide in solution B to generate Cu2O, and can make Cu2O exist stably.

[0054] For example, after stirring solution B for 15 minutes, 50 mL of ascorbic acid solution with a concentration of 0.01-0.3 mol / L was added dropwise to solution B at a dropping rate of 5 mL / min. After stirring evenly, the solution was aged at room temperature for 1-5 hours to form a brick-red precipitate.

[0055] In step S4, the brick-red precipitate obtained in step S3 is separated, washed several times with ethanol and deionized water to remove impurities, dried in an oven at 60° C. for 12 h, and ground to obtain cubic Cu2O.

[0056] That is, in the embodiment of the present invention, copper sulfate, sodium citrate, sodium hydroxide solution and ascorbic acid solution are reacted to obtain Cu2O with a cubic morphology.

[0057] After obtaining the cubic Cu2O, in step S5, the cubic Cu2O is mixed with deionized water to obtain a mixed solution, and then ammonium molybdate and thiourea are added and stirred uniformly to obtain solution C.

[0058] In one embodiment, the ammonium molybdate is ammonium heptamolybdate tetrahydrate, and the mass ratio of the cubic Cu2O, the ammonium heptamolybdate tetrahydrate and the thiourea is (1.1-1.3):(20-30):(8-106).

[0059] For example, the ammonium molybdate is ammonium heptamolybdate tetrahydrate, and 1.1-1.3 parts of cubic Cu2O are mixed with 28-32 mL of deionized water to obtain a mixed reaction, and then 20-30 parts of ammonium heptamolybdate tetrahydrate and 8-50 parts of thiourea are stirred for 5-30 minutes until a brick red solution is formed, thereby obtaining solution C.

[0060] In step S6, the heating reaction temperature is 160-230° C., and the reaction time is 12-30 h.

[0061] By controlling the reaction temperature within the range of 160-230°C and the interlayer distance during the synthesis of molybdenum sulfide, the directional transformation of 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 HER performance.

[0062] Another embodiment of the present invention provides a molybdenum sulfide / copper sulfide composite catalyst, which is prepared using the above-mentioned method for preparing the molybdenum sulfide / copper sulfide composite catalyst.

[0063] The shape of the molybdenum sulfide / copper sulfide is a cubic flower ball, and the molybdenum sulfide / copper sulfide includes 1T phase molybdenum sulfide.

[0064] The beneficial effects of the molybdenum sulfide / copper sulfide composite catalyst provided in the embodiment of the present invention compared with the prior art are the same as the preparation method of the molybdenum sulfide / copper sulfide composite catalyst, which will not be repeated here.

[0065] Yet another embodiment of the present invention provides a working electrode for electrocatalytic hydrogen evolution reaction, which is prepared using the molybdenum sulfide / copper sulfide composite catalyst described above.

[0066] In addition, the embodiments of the present invention also provide a method for preparing the working electrode for the electrocatalytic hydrogen evolution reaction as described above, such as Figure 2 As shown, the following steps are included:

[0067] Step T1, mixing 20 mg of the molybdenum sulfide / copper sulfide composite catalyst and 10 mg of carbon black, grinding the mixture, washing, drying, and grinding the mixture again to obtain a pretreated catalyst;

[0068] Step T2, adding 5 mg of the pretreated catalyst to a mixed solution of ethanol and water, and ultrasonically dispersing the mixture to form a catalyst solution;

[0069] Step T3: drop 5 μL of the catalyst solution onto the surface of the glassy carbon electrode, add 5 μL of naphthol after drying, and dry again to obtain a working electrode for the electrocatalytic hydrogen evolution reaction.

[0070] The beneficial effects of the working electrode for the electrocatalytic hydrogen evolution reaction provided by the embodiment of the present invention compared with the prior art are the same as the preparation method of the molybdenum sulfide / copper sulfide composite catalyst, which will not be repeated here.

[0071] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. The experimental methods in the following examples where specific conditions are not specified are generally based on the conditions recommended by the manufacturer.

[0072] Example 1

[0073] 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.

[0074] 1.2. Add 20 mL of 1.25 M NaOH solution to solution A under stirring and stir for 15 minutes to obtain solution B.

[0075] 1.3. Add 50 mL of 0.03 M ascorbic acid solution to solution B and stir for 3 min to obtain a mixed solution. Then, age the solution at room temperature for 1 h to form a brick-red precipitate. Collect the brick-red precipitate, wash it with water and ethanol several times, dry it, and grind it to obtain cubic cuprous oxide.

[0076] 1.4. Mix 60 mg of cubic cuprous oxide and 28 mL of deionized water to obtain a mixed solution. Then, add 1.02 g of ammonium heptamolybdate tetrahydrate and 0.4 g of thiourea to the mixed solution and stir to form a brick-red solution, obtaining Solution C.

[0077] 1.5. Transfer solution C to a stainless steel reactor lined with Teflon, react at 180°C for 20 h, cool to room temperature, wash with ethanol and water three times each, and vacuum dry at 60°C for 12 h to obtain a molybdenum sulfide / copper sulfide composite catalyst.

[0078] Example 2

[0079] 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.

[0080] 2.2. Add 20 mL of 1.25 M NaOH solution to solution A under stirring and stir for 15 minutes to obtain solution B.

[0081] 2.3. Add 50 mL of 0.03 M ascorbic acid solution to solution B and stir for 3 min to obtain a mixed solution. Then, age the solution at room temperature for 1 h to form a brick-red precipitate. The brick-red precipitate is collected, washed with water and ethanol several times, dried, and ground to obtain cubic cuprous oxide.

[0082] 2.4. Mix 65 mg of cubic cuprous oxide and 28 mL of deionized water to obtain a mixed solution. Then, add 1.02 g of ammonium heptamolybdate tetrahydrate and 0.4 g of thiourea to the mixed solution and stir to form a brick-red solution, obtaining Solution C.

[0083] 2.5. Solution C was transferred to a stainless steel reactor lined with Teflon, reacted at 180°C for 20 h, cooled to room temperature, washed with ethanol and water three times each, and vacuum dried at 60°C for 12 h to obtain a molybdenum sulfide / copper sulfide composite catalyst.

[0084] 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.

[0086] 3.2. Add 20 mL of 1.25 M NaOH solution to Solution A under stirring and stir for 15 minutes to obtain Solution B.

[0087] 3.3. Add 50 mL of 0.03 M ascorbic acid solution to solution B and stir for 3 min to obtain a mixed solution. Then, age the solution at room temperature for 1 h to form a brick-red precipitate. The brick-red precipitate is collected, washed with water and ethanol several times, dried, and ground to obtain cubic cuprous oxide.

[0088] 3.4. Mix 55 mg of cubic cuprous oxide and 28 mL of deionized water to obtain a mixed solution. Then, add 1.24 g of ammonium heptamolybdate tetrahydrate and 2.28 g of thiourea to the mixed solution and stir to form a brick-red solution, obtaining Solution C.

[0089] 3.5. Transfer solution C to a stainless steel reactor lined with Teflon, react at 180°C for 20 h, cool to room temperature, wash with ethanol and water three times each, and vacuum dry at 60°C for 12 h to obtain a molybdenum sulfide / copper sulfide composite catalyst.

[0090] Example 4

[0091] 4.1. 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.

[0092] 4.2. Add 20 mL of 1.25 M NaOH solution to Solution A under stirring and stir for 15 minutes to obtain Solution B.

[0093] 4.3. Add 50 mL of 0.03 M ascorbic acid solution to solution B and stir for 3 min to obtain a mixed solution. Then, age the solution at room temperature for 1 h to form a brick-red precipitate. Collect the brick-red precipitate, wash it with water and ethanol several times, dry it, and grind it to obtain cubic cuprous oxide.

[0094] 4.4. Mix 60 mg of cubic cuprous oxide and 28 mL of deionized water to obtain a mixed solution. Then, add 1.5 g of ammonium heptamolybdate tetrahydrate and 5.3 g of thiourea to the mixed solution and stir to form a brick-red solution, obtaining Solution C.

[0095] 4.5. Transfer solution C to a Teflon-lined stainless steel reactor and react at 180°C for 20 h. Then, cool to room temperature, wash with ethanol and water three times each, and vacuum dry at 60°C for 12 h to obtain a molybdenum sulfide / copper sulfide composite catalyst.

[0096] Comparative Example 1

[0097] 1.02 g of ammonium heptamolybdate tetrahydrate was dissolved in 28 mL of deionized water, and 0.4 g of thiourea was added and stirred until the solution became clear. The above solution was transferred to a Teflon-lined stainless steel reactor and reacted at 180 ° C for 20 h. The mixture was cooled to room temperature, washed with ethanol and water three times each, and dried in a vacuum drying oven at 60 ° C for 12 h to obtain flower-shaped molybdenum sulfide.

[0098] Experimental Example 1

[0099] The molybdenum sulfide / copper sulfide composite catalyst obtained in Example 1 was subjected to X-ray diffraction analysis and observed using a scanning electron microscope and a transmission electron microscope.

[0100] Figure 3 is the X-ray diffraction pattern of the molybdenum sulfide / copper sulfide composite catalyst in Example 1, from Figure 3 It can be seen that the diffraction peaks appearing in the X-ray diffraction pattern of the molybdenum sulfide / copper sulfide composite catalyst in Example 1 correspond to the standard molybdenum sulfide diffraction peaks and the standard copper sulfide diffraction peaks, indicating that the molybdenum sulfide / copper sulfide composite catalyst prepared in Example 1 contains both molybdenum sulfide and copper sulfide.

[0101] Figure 4 The scanning electron microscope image of the molybdenum sulfide / copper sulfide composite catalyst in Example 1 is shown in FIG. Figure 4 It can be seen that its microscopic morphology is cubic flower ball.

[0102] Figure 5 is a transmission electron microscope image of the molybdenum sulfide / copper sulfide composite catalyst in Example 1, wherein Figure 5 (a) and Figure 5 Middle (b) are low and high magnification transmission electron microscopy images, Figure 5 (c) is Figure 5 The enlarged image of the left box area in (b) Figure 5 (d) is Figure 5 The lattice fringe spacing diagram in the right box of (b). Figure 5 , the molybdenum sulfide (100) crystal plane and the copper sulfide (103) crystal plane of the molybdenum sulfide / copper sulfide composite catalyst in Example 1 can be analyzed.

[0103] Experimental Example 2

[0104] The hydrogen evolution reaction performance of the samples prepared in Example 1, Example 2, and Comparative Example 1 was tested. The specific testing method was as follows: the materials prepared in Example 1, Example 2, and Comparative Example 1 were each made into a working electrode for the electrocatalytic hydrogen evolution reaction, a saturated calomel electrode was used as a reference electrode, and a platinum electrode was used as a counter electrode to form a three-electrode system. The system was connected to an electrochemical workstation and the electrocatalytic hydrogen evolution performance of the materials was tested in a 0.5 M H2SO4 electrolyte. The samples were subjected to HER polarization curve analysis at a scan rate of 50 mV / s.

[0105] The method for preparing the working electrode for the electrocatalytic hydrogen evolution reaction is as follows:

[0106] 20 mg of molybdenum sulfide / copper sulfide composite catalyst (or molybdenum sulfide catalyst) and 10 mg of carbon black were mixed and ground, washed, dried, and then ground again to obtain a pretreated catalyst;

[0107] 5 mg of the pretreated catalyst was added to a mixed solution of ethanol and water and dispersed by ultrasonication to form a catalyst solution;

[0108] 5 μL of catalyst solution was dropped onto the surface of the glassy carbon electrode, and after drying, 5 μL of naphthol was added dropwise, and after drying again, a working electrode for electrocatalytic hydrogen evolution reaction was obtained.

[0109] The test results are as follows Figure 6-Figure 9 shown.

[0110] Figure 6 The polarization curve comparison of the samples prepared in Example 1 and Comparative Example 1 in 0.5M H2SO4 electrolyte is shown in Figure 2. Figure 6 It can be seen that the molybdenum sulfide / copper sulfide composite catalyst prepared in Example 1 has a high current density of 10 mA·cm -2 The overpotential of the molybdenum sulfide prepared in Comparative Example 1 is 85mV at a current density of 10mA·cm -2 The overpotential is 350 mV, indicating that the molybdenum sulfide / copper sulfide composite catalyst prepared in Example 1 has a smaller overpotential and can effectively reduce the reaction activation energy.

[0111] Figure 7 The Tafel curve comparison of the samples prepared in Example 1 and Comparative Example 1 in 0.5M H2SO4 electrolyte is shown in FIG. Figure 7 It can be seen that Example 1 has a smaller Tafel slope, indicating that it can obtain a larger current when a smaller potential is applied. The molybdenum sulfide / copper sulfide composite catalyst prepared in Example 1 is more conducive to hydrogen evolution.

[0112] Figure 8 and Figure 9The polarization curves and Tafel plots of the samples prepared in Example 1 and Example 2 in 0.5M H2SO4 electrolyte are shown in FIG. Figure 8 and Figure 9 It can be seen that the molybdenum sulfide / copper sulfide composite catalysts prepared in Example 1 and Example 2 both have lower overpotentials and smaller Tafel slopes, indicating that the molybdenum sulfide / copper sulfide composite catalysts prepared in Example 1 and Example 2 of the present invention have excellent electrocatalytic hydrogen evolution reaction performance.

[0113] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for preparing a molybdenum sulfide / copper sulfide composite catalyst, characterized in that: The following steps are involved: Step S1, dissolving copper sulfate and sodium citrate in deionized water to obtain solution A; Step S2, adding sodium hydroxide solution to the solution A under stirring to obtain solution B; Step S3, adding ascorbic acid solution dropwise to the solution B, stirring and mixing, and aging at room temperature to form a brick-red precipitate; Step S4, separating the brick-red precipitate, washing, drying, and grinding to obtain cubic cuprous oxide; Step S5, mixing the cubic cuprous oxide with deionized water to obtain a mixed solution, and then adding ammonium molybdate and thiourea to form a brick-red solution to obtain solution C; Step S6: transferring the solution C to a reactor, heating for reaction, cooling to room temperature, washing, and drying to obtain a molybdenum sulfide / copper sulfide composite catalyst.

2. The method for preparing the molybdenum sulfide / copper sulfide composite catalyst according to claim 1, wherein In the step S1, the molar ratio of the copper sulfate to the sodium citrate is 15:1-5:

9.

3. The method for preparing the molybdenum sulfide / copper sulfide composite catalyst according to claim 1, wherein In step S2, the concentration of the sodium hydroxide solution is 0.5-2 mol / L.

4. The method for preparing the molybdenum sulfide / copper sulfide composite catalyst according to claim 1, wherein In step S3, the concentration of the ascorbic acid solution is 0.01-0.3 mol / L, the dropping speed is 5 mL / min, and the aging time is 1-5 h.

5. The method for preparing the molybdenum sulfide / copper sulfide composite catalyst according to claim 1, wherein In the step S5, the ammonium molybdate is ammonium heptamolybdate tetrahydrate, and the mass ratio of the cubic cuprous oxide, the ammonium heptamolybdate tetrahydrate and the thiourea is (1.1-1.3):(20-30):(8-106).

6. The method for preparing the molybdenum sulfide / copper sulfide composite catalyst according to claim 1, wherein In the step S6, the solution C is transferred to a reactor and reacted at a temperature of 160-230° C. for 12-30 hours.

7. A molybdenum sulfide / copper sulfide composite catalyst, characterized in that: The catalyst is prepared by the method for preparing the molybdenum sulfide / copper sulfide composite catalyst according to any one of claims 1 to 6.

8. The molybdenum sulfide / copper sulfide composite catalyst according to claim 7, characterized in that The molybdenum sulfide / copper sulfide has a cubic flower-shaped shape, and the molybdenum sulfide / copper sulfide includes 1T phase molybdenum sulfide.

9. A working electrode for electrocatalytic hydrogen evolution reaction, characterized in that It is prepared by using the molybdenum sulfide / copper sulfide composite catalyst according to any one of claims 7 to 8.

10. A method for preparing a working electrode for electrocatalytic hydrogen evolution reaction, for preparing the working electrode for electrocatalytic hydrogen evolution reaction according to claim 9, characterized in that: The following steps are involved: Step T1, mixing 20 mg of the molybdenum sulfide / copper sulfide composite catalyst and 10 mg of carbon black, grinding the mixture, washing, drying, and grinding the mixture again to obtain a pretreated catalyst; Step T2, adding 5 mg of the pretreated catalyst to a mixed solution of ethanol and water, and ultrasonically dispersing the mixture to form a catalyst solution; Step T3: drop 5 μL of the catalyst solution onto the surface of the glassy carbon electrode, add 5 μL of naphthol after drying, and dry again to obtain a working electrode for the electrocatalytic hydrogen evolution reaction.

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