Preparation method and application of transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure

Abstract

The invention is applicable to the technical field of materials, and provides a preparation method and application of a transition metal selenide / metal-phase molybdenum disulfide in-plane heterostructure, a metal-phase molybdenum disulfide nanosheet is used as a main body, a 2-5nm transition metal selenide nanocluster is embedded into the metal-phase molybdenum disulfide nanosheet, and the transition metal selenide / metal-phase molybdenum disulfide in-plane heterostructure is prepared. And the two are in the same plane. The preparation method comprises the following specific steps: by taking a transition metal sulfide in-plane heterostructure prepared by a two-step hydrothermal method as a precursor, converting in-plane transition metal sulfide into selenide thereof by a gas-phase selenylation method on the premise of reserving metal-phase molybdenum disulfide, so as to obtain the transition metal selenide / metal-phase molybdenum disulfide in-plane heterostructure. And the prepared transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure powder and a self-supporting electrode are used as a water electrolysis hydrogen evolution catalyst. The material is simple in preparation process, low in price, green and environment-friendly, and has ultrahigh catalytic activity as a water electrolysis hydrogen evolution catalyst.

Description

Technical Field

[0001] The invention belongs to the field of materials, and in particular relates to a preparation method and application of a transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure. Background Art

[0002] Currently, the electrochemical hydrogen evolution reaction (HER) is considered a key technology for green energy storage and utilization, but its scalability is limited by the reserves and costs of precious metal-based catalysts. 2 ) shows great application prospects as a cost-effective and efficient electrocatalytic hydrogen evolution catalyst. Both theoretical and experimental studies have shown that MoS 2 The few active sites in the molybdenum disulfide are located at the edges and defects, while the basal plane with a large number of active sites is catalytically inert, which seriously limits its overall catalytic activity. In nature, molybdenum disulfide exists in three main forms: 1T-MoS 2 , 2H-MoS 2 and 3R-MoS 2 Among the three, the metallic phase molybdenum disulfide (1T-MoS 2 ) and the semiconductor phase MoS2 (2H-MoS 2 ) due to its good metallic conductivity, its charge transfer resistance is significantly reduced, showing excellent electrocatalytic hydrogen evolution activity.

[0003] Studies have shown that heterostructures can activate the basal plane of MoS2 through various effects, including the creation of new catalytic sites, enhanced conductivity, and improved reaction kinetics, thereby improving catalytic activity. 2 Most of the heterostructures based on 1T-MoS are out-of-plane heterostructures, i.e. 2 The nanosheets are bonded to the second phase through chemical bonds or through weak bonding forces such as out-of-plane van der Waals interactions, such as the second phase deposited on 1T-MoS 2 The structure on the nanosheet substrate, or vice versa, 1T-MoS 2 The nanosheets are laterally deposited on the second phase. Such an out-of-plane heterostructure is not only easy to cause the heterogeneous interface to be shielded, but also easy to cause 1T-MoS 2 The basal active sites are shielded and cannot fully contact the electrolyte, thus limiting its hydrogen evolution catalytic activity.

[0004] MoS2 is very prone to phase transition under high temperature conditions, resulting in a transition from a metallic phase to a semiconductor phase. Transition metal selenides can often be prepared by high-temperature vapor phase selenization, which makes the heterostructure of metallic phase MoS2-based transition metal selenides rarely reported.

[0005] At present, the construction of out-of-plane heterostructures based on metallic phase MoS2 has limited regulation and activation of its basal plane sulfur atoms, which seriously restricts its electrocatalytic hydrogen evolution activity. At the same time, the insufficient stability of metallic phase MoS2 at high temperature also limits its construction of heterostructures with transition metal selenides. Summary of the invention

[0006] The present invention aims to provide a method for preparing a transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure and its application, aiming to solve the problems raised in the above-mentioned background technology.

[0007] The present invention is achieved in this way: a transition metal selenide / metal phase molybdenum disulfide in-plane heterogeneous structure is used. The structure uses basic carbonate as a structural template and metal phase molybdenum disulfide nanosheets as a main body. Transition metal selenide nanoclusters are uniformly embedded in the metal phase molybdenum disulfide nanosheets and are in the same plane as the metal phase molybdenum disulfide. The size of the nanoclusters is 2-5nm; the content of metal phase molybdenum disulfide in the molybdenum disulfide is 60-75%, and the metal phase molybdenum disulfide in the structure has thermal stability.

[0008] In a further technical solution, the transition metal selenide includes but is not limited to cobalt selenide, nickel selenide, iron selenide, and zinc selenide, and the thermal stability of molybdenum disulfide means that the metal phase molybdenum disulfide in the precursor transition metal sulfide metal phase molybdenum disulfide in-plane heterogeneous structure is not converted into semiconductor phase molybdenum disulfide after a high-temperature gas phase selenization reaction at 350°C. The transition metal selenide / metal phase molybdenum disulfide in-plane heterogeneous structure can effectively improve the basal activity of the metal phase molybdenum disulfide, thereby reducing the overpotential of the electrocatalytic hydrogen evolution reaction, and ultimately achieving efficient hydrogen production by electrolysis of water.

[0009] Another object of the present invention is to provide a method for preparing a transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure, comprising the following steps:

[0010] Step 1: Prepare a transition metal basic carbonate precursor, specifically dissolving a transition metal salt and an appropriate amount of a nucleating agent in a mixed solution of water and ethanol, loading the mixture into a closed reactor, and preparing the basic carbonate by a hydrothermal method. The hydrothermal reaction temperature is 90-140° C., and the reaction time is 5-12 hours.

[0011] Step 2: Prepare a transition metal sulfide metal phase molybdenum disulfide in-plane heterostructure, specifically, take the transition metal basic carbonate prepared in step 1, add molybdenum trioxide (as a molybdenum source), a sulfur source, and an appropriate amount of a reducing agent in proportion, and add an appropriate amount of water to mix evenly, place the mixed solution in a closed reactor for hydrothermal reaction, the reaction temperature is 180-240°C, and the reaction time is 8-24h.

[0012] Step three: prepare a transition metal selenide / metallic phase molybdenum disulfide in-plane heterostructure, specifically placing the transition metal sulfide / metallic phase molybdenum disulfide in-plane heterostructure obtained in step two in a selenium vapor atmosphere for a vapor phase selenization reaction, wherein the reaction temperature of the vapor phase selenization reaction is 300-400°C and the reaction time is 1-3h.

[0013] Step 4: The transition metal selenide / metal phase molybdenum disulfide powder obtained by the gas phase selenization reaction in step 3 is washed with carbon disulfide, ethanol and deionized water respectively and dried to obtain a product transition metal selenide / metal phase molybdenum disulfide in-plane heterogeneous structure.

[0014] According to a further technical solution, in step one, the transition metal salt mainly includes cobalt nitrate, iron nitrate, nickel nitrate and zinc nitrate, and the nucleating agent includes urea and ammonium fluoride.

[0015] The sulfur source in step 2 is selected from one or more of thioacetamide or sodium sulfide, and the reducing agent is selected from any one or more of urea or hydrazine hydrate.

[0016] In step 1, the ratio of water to ethanol is 1:1;

[0017] In the step 2, the ratio of the number of molybdenum atoms in the molybdenum trioxide to the number of sulfur atoms in the sulfur source is 1:5-40.

[0018] According to a further technical solution, in step 3, the selenium vapor atmosphere is formed by decomposing selenium powder at high temperature in an inert atmosphere, the inert atmosphere includes pure nitrogen and argon, and the atmosphere should be higher than atmospheric pressure during the reaction;

[0019] The mass ratio of the selenium powder to the transition metal sulfide metal phase molybdenum disulfide in-plane heterogeneous structure powder is 40-100:1.

[0020] A further technical solution is that in the step three, the temperature of the gas phase selenization reaction is 350°C, at which temperature the transition metal sulfide in the surface undergoes a selenization reaction in the atmosphere of selenium vapor to be converted into a transition metal selenide; while the metal phase molybdenum disulfide will neither undergo a selenization reaction to be molybdenum selenide nor undergo a phase transition to a semiconductor phase.

[0021] Another object of the present invention is to provide a self-supporting electrode, based on the transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure prepared by the above-mentioned transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure method, wherein the self-supporting electrode is formed by growing a transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure nanosheet array on a conductive substrate;

[0022] The method for preparing the self-supporting electrode comprises the following specific steps:

[0023] Step 1: Preparation of transition metal basic carbonate precursor, specifically dissolving transition metal salt and appropriate amount of nucleating agent in a mixed solution of water and ethanol, loading into a closed reactor, adding a conductive substrate to the mixed solution, and preparing basic carbonate grown on the conductive substrate by a hydrothermal method. The conductive substrate includes pretreated carbon cloth, titanium sheet and nickel foam; the hydrothermal reaction temperature is 90-140°C, and the reaction time is 5-12h.

[0024] Step 2: Prepare a transition metal sulfide / metal phase molybdenum disulfide in-plane heterostructure, specifically using molybdenum trioxide (as a molybdenum source), a sulfur source, and an appropriate amount of a reducing agent, and adding an appropriate amount of water to mix evenly, while placing the conductive substrate containing the basic carbonate nanowire array prepared in step 1 in the mixed solution, placing the mixed solution in a closed reactor for hydrothermal reaction to obtain a transition metal sulfide / metal phase molybdenum disulfide in-plane heterostructure grown on the conductive substrate, the reaction temperature is 180-240°C, and the reaction time is 8-24h.

[0025] Step three: prepare a transition metal selenide / metallic phase molybdenum disulfide in-plane heterostructure, specifically placing the conductive substrate with the nanosheet array grown with the transition metal sulfide / metallic phase molybdenum disulfide in-plane heterostructure obtained in step two in a selenium vapor atmosphere for a vapor phase selenization reaction, wherein the reaction temperature of the vapor phase selenization reaction is 300-400°C and the reaction time is 1-3h.

[0026] Step 4: The conductive substrate sample obtained after the gas phase selenization reaction is washed with carbon disulfide, ethanol and deionized water respectively and dried to obtain the self-supporting electrode of the transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure.

[0027] Another object of the present invention is to provide an application of a self-supporting electrode, and the application of the transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure self-supporting electrode in the direction of electrocatalytic hydrogen evolution.

[0028] The present invention provides a method for preparing a transition metal selenide / metal phase molybdenum disulfide in-plane heterogeneous structure self-supporting electrode. The method uses a basic carbonate grown on a conductive substrate as a template, adds a molybdenum source and a sulfur source for further hydrothermal reaction, and rapidly sulfides, by utilizing the difference in the dissolution rate of the transition metal and the molybdenum source during the reaction and the defects on the metal phase molybdenum disulfide basal surface prepared by hydrothermal synthesis. During the dissolution process, cobalt ions may attach to these defect sites and contact with the sulfur source in the solution to generate transition metal sulfides, and successfully prepare a transition metal sulfide metal phase molybdenum disulfide in-plane heterogeneous structure self-supporting electrode grown on a conductive substrate. The control of the selenization temperature utilizes the difference in the selenization temperature of the transition metal (iron, cobalt, nickel, zinc, etc.) and molybdenum, so as to selectively selenize the transition metal nanoclusters, while the metal phase molybdenum disulfide is retained. The synthesis process method is simple and easy to operate, the product is easy to obtain, and has broad prospects.

[0029] In particular, the self-supporting electrode of the cobalt diselenide / metallic phase molybdenum disulfide in-plane heterostructure showed excellent hydrogen evolution performance when used as the negative electrode for electrocatalytic hydrogen evolution. In 1.0 M potassium hydroxide electrolyte, the current density was 10 mA / cm 2 It shows an overpotential of 48 mV, which exceeds that of most molybdenum disulfide-based hydrogen evolution catalysts reported so far. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a scanning electron microscope (SEM) image of a self-supporting electrode of a cobalt diselenide / metallic phase molybdenum disulfide in-plane heterostructure;

[0031] Figure 2 This is a high-resolution transmission electron microscopy (HRTEM) image of the cobalt diselenide / metallic phase molybdenum disulfide in-plane heterostructure;

[0032] Figure 3 Linear voltammetric curves of cobalt diselenide / metallic molybdenum disulfide in-plane heterostructure catalyst and comparative example in 1.0 M potassium hydroxide.

[0033] Figure 4 Tafel images of the cobalt diselenide / metal phase molybdenum disulfide in-plane heterostructure catalyst and comparative example. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0035] The following specific embodiments describe the specific implementation of the present invention in detail.

[0036] An embodiment of the present invention provides a transition metal selenide / metal phase molybdenum disulfide in-plane heterogeneous structure, which uses basic carbonate as a structural template, and uniformly embeds transition metal selenide nanoclusters in the metal phase molybdenum disulfide surface, which is in the same plane as the metal phase molybdenum disulfide, wherein the content of the metal phase in the molybdenum disulfide is 60-75%; the metal phase molybdenum disulfide in the structure has thermal stability.

[0037] As a preferred embodiment of the present invention, the transition metal selenide refers to cobalt selenide, nickel selenide, iron selenide and zinc selenide; the thermal stability of the metal phase molybdenum disulfide in the structure specifically refers to that the metal phase molybdenum disulfide in the precursor transition metal sulfide metal phase molybdenum disulfide in-plane heterostructure has undergone a 350°C gas phase selenization reaction, and the metal phase molybdenum disulfide therein has not transformed into a semiconductor phase. The transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure can effectively enhance the hydrogen adsorption capacity of the sulfur atoms on the basal plane of the metal phase molybdenum disulfide, thereby reducing the overpotential required for the hydrogen evolution reaction, and then achieving efficient electrochemical hydrogen production.

[0038] An embodiment of the present invention provides a method for preparing a transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure, comprising the following steps:

[0039] Step 1: Prepare a transition metal basic carbonate precursor, specifically dissolving a transition metal salt and an appropriate amount of a nucleating agent in a mixed solution of water and ethanol, loading the mixture into a closed reactor, and preparing the basic carbonate by a hydrothermal method. The hydrothermal reaction temperature is 90-140° C., and the reaction time is 5-12 hours.

[0040] Step 2: Prepare a transition metal sulfide / metal phase molybdenum disulfide in-plane heterostructure, specifically, take the transition metal basic carbonate prepared in step 1, add molybdenum trioxide (as a molybdenum source), a sulfur source, and an appropriate amount of a reducing agent in proportion, and add an appropriate amount of water to mix evenly, place the mixed solution in a closed reactor for hydrothermal reaction, the reaction temperature is 180-240°C, and the reaction time is 8-24h.

[0041] Step three: prepare a transition metal selenide / metallic phase molybdenum disulfide in-plane heterostructure, specifically placing the transition metal sulfide / metallic phase molybdenum disulfide in-plane heterostructure obtained in step two in a selenium vapor atmosphere for a vapor phase selenization reaction, wherein the reaction temperature of the vapor phase selenization reaction is 300-400°C and the reaction time is 1-3h.

[0042] Step 4: The transition metal selenide / metal phase molybdenum disulfide powder obtained by the gas phase selenization reaction in step 3 is washed with carbon disulfide, ethanol and deionized water respectively and dried to obtain a product transition metal selenide / metal phase molybdenum disulfide in-plane heterogeneous structure.

[0043] As a preferred embodiment of the present invention, in step 1, the transition metal salt mainly includes cobalt nitrate, nickel nitrate, iron nitrate, zinc nitrate, and the nucleating agent includes urea and ammonium fluoride; the sulfur source in step 2 is selected from one or more of thioacetamide or sodium sulfide, and the reducing agent comes from any one or more of urea or hydrazine hydrate. The ratio of water to ethanol is 1:1; the ratio of the number of molybdenum atoms in the molybdenum trioxide to the number of sulfur atoms in the sulfur source is 1:5-40.

[0044] As a preferred embodiment of the present invention, in step 3, the selenium vapor atmosphere is formed by decomposing selenium powder at high temperature in an inert atmosphere, the inert atmosphere includes pure nitrogen and argon, and the atmosphere should be higher than atmospheric pressure during the reaction;

[0045] The carbon disulfide is used to wash away the elemental selenium on the surface of the sample; the mass ratio of the selenium powder to the transition metal sulfide metal phase molybdenum disulfide in-plane heterogeneous structure powder is 40-100:1.

[0046] In a preferred embodiment of the present invention, in the step three, the temperature of the gas phase selenization reaction is 350°C, at which temperature the transition metal sulfide in the surface undergoes a selenization reaction in an atmosphere of selenium vapor to be converted into a transition metal selenide; while the metal phase molybdenum disulfide will neither undergo a selenization reaction to be molybdenum selenide nor undergo a phase transformation into a semiconductor phase.

[0047] A self-supporting electrode provided by an embodiment of the present invention is a transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure prepared by the above-mentioned transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure method, wherein the self-supporting electrode is formed by growing a transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure nanosheet array on a conductive substrate;

[0048] The method for preparing the self-supporting electrode comprises the following specific steps:

[0049] Step 1: Preparation of transition metal basic carbonate precursor, specifically dissolving transition metal salt and appropriate amount of nucleating agent in a mixed solution of water and ethanol, loading into a closed reactor, adding a conductive substrate to the mixed solution, and preparing basic carbonate grown on the conductive substrate by a hydrothermal method. The conductive substrate includes pretreated carbon cloth, titanium sheet and nickel foam; the hydrothermal reaction temperature is 90-140°C, and the reaction time is 5-12h.

[0050] Step 2: Prepare a transition metal sulfide / metal phase molybdenum disulfide in-plane heterostructure, specifically using molybdenum trioxide (as a molybdenum source), a sulfur source, and an appropriate amount of a reducing agent, and adding an appropriate amount of water to mix evenly, while placing the conductive substrate containing the basic carbonate nanowire array prepared in step 1 in the mixed solution, placing the mixed solution in a closed reactor for hydrothermal reaction to obtain a transition metal sulfide / metal phase molybdenum disulfide in-plane heterostructure grown on the conductive substrate, the reaction temperature is 180-240°C, and the reaction time is 8-24h.

[0051] Step three: prepare a transition metal selenide / metallic phase molybdenum disulfide in-plane heterostructure, specifically placing the conductive substrate with the nanosheet array grown with the transition metal sulfide / metallic phase molybdenum disulfide in-plane heterostructure obtained in step two in a selenium vapor atmosphere for a vapor phase selenization reaction, wherein the reaction temperature of the vapor phase selenization reaction is 300-400°C and the reaction time is 1-3h.

[0052] Step 4: The conductive substrate sample obtained after the gas phase selenization reaction is washed with carbon disulfide, ethanol and deionized water respectively and dried to obtain the self-supporting electrode of the transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure.

[0053] In an embodiment of the present invention, the conductive substrate is subjected to ultrasonic treatment with an acid solution and an organic solvent to remove impurities and organic residues, and the hydrophobic surface is converted into a hydrophilic surface, and finally washed with deionized water. Note that after the short-time ultrasonic treatment is completed, the conductive substrate is stored in deionized water for standby use to avoid corrosion; the acid solution is a hydrochloric acid and nitric acid solution with a concentration of 3 mol / L; the organic solvent is acetone and ethanol.

[0054] An embodiment of the present invention provides an application of a self-supporting electrode, wherein the transition metal selenide metal phase molybdenum disulfide in-plane heterostructure self-supporting electrode is applied in the direction of electrocatalytic hydrogen evolution.

[0055] The following is a specific example to verify the effect of this method:

[0056] Embodiment 1: A method for preparing a cobalt diselenide metal phase molybdenum disulfide in-plane heterostructure, comprising the following steps:

[0057] Step 1: Weigh 0.56 g of hexahydrate and cobalt nitrate, 0.78 g of urea, dissolve them in 12 ml of deionized water, add 12 ml of anhydrous ethanol to the solution, place it in an oven at 95° C. for hydrothermal reaction for 6 hours to obtain basic cobalt carbonate nanowire arrays.

[0058] Step 2: Weigh 0.1 g of basic cobalt carbonate, use basic cobalt carbonate as a template, weigh 90 mg of molybdenum trioxide, 1.5 g of sodium sulfide, 0.45 mg of thioacetamide, and 1.8 g of urea, dissolve them in 25 ml of deionized water and stir evenly to form a uniform solution, place the solution in a 50 ml reactor, and place it in an oven at 200°C for 12 hours.

[0059] Step 3: After the hydrothermal reaction is completed, the product is naturally cooled to room temperature, and the solid product is separated and centrifuged, washed several times with deionized water and ethanol, respectively, and the solid product is collected and vacuum dried to obtain a powder of cobalt sulfide metal phase molybdenum disulfide / in-plane heterogeneous structure;

[0060] Step 4: Place the obtained powder in a porcelain boat, and place 200 mg of selenium powder in another porcelain boat and place them together in a tube furnace. Note that the porcelain boat containing the sample is located downstream of the air flow. Heat at 350°C in an inert atmosphere (Ar) for 90 minutes.

[0061] Step 5: After washing the powder obtained by the gas phase selenization reaction with carbon disulfide, ethanol and deionized water respectively and drying, the obtained powder is a powder of a cobalt diselenide metal phase molybdenum disulfide-based in-plane heterogeneous structure.

[0062] Embodiment 2: A method for preparing a zinc diselenide metal phase molybdenum disulfide in-plane heterostructure, comprising the following steps:

[0063] Compared with Example 1, zinc nitrate was used to replace cobalt nitrate, and the rest was the same as Example 1.

[0064] Embodiment 3: A method for preparing an iron diselenide metal phase molybdenum disulfide in-plane heterostructure, comprising the following steps:

[0065] Compared with Example 1, cobalt nitrate was replaced by iron nitrate, and the rest was the same as Example 1.

[0066] Embodiment 4: A method for preparing a nickel diselenide metal phase molybdenum disulfide in-plane heterostructure, comprising the following steps:

[0067] Compared with Example 1, cobalt nitrate is replaced by nickel nitrate, and the rest is the same as Example 1.

[0068] Embodiment 5: A method for preparing a cobalt diselenide metal phase molybdenum disulfide in-plane heterostructure self-supporting electrode, comprising the following steps:

[0069] Step 1: Weigh 0.56g of hexahydrate and cobalt nitrate, 0.78g of urea, dissolve in 12ml of deionized water, add 12ml of anhydrous ethanol to the solution, and then add the conductive substrate - carbon cloth (2*2cm 2), the conductive substrate solution was placed in a 50 ml reactor, and placed in an oven for hydrothermal reaction at 95° C. for 6 h to obtain a basic cobalt carbonate nanowire array grown on the carbon cloth.

[0070] Step 2: Weigh 90 mg of molybdenum trioxide, 1.5 g of sodium sulfide, 0.45 g of thioacetamide, and 1.8 g of urea, dissolve them in 25 ml of deionized water and stir evenly to form a uniform solution, place the solution in a 50 ml reactor, place the basic cobalt carbonate nanowire array grown on the carbon cloth obtained in the first step in the reactor, and hydroheat in an oven at 200°C for 12 hours.

[0071] Step 3: After the hydrothermal reaction is completed, the carbon cloth is naturally cooled to room temperature, and the carbon cloth is taken out, washed several times with deionized water and ethanol respectively, and vacuum dried to obtain a cobalt sulfide metal phase molybdenum disulfide in-plane heterogeneous structure supported on the carbon cloth;

[0072] Step 4: Place the obtained carbon cloth sample in a porcelain boat, and place 200 mg of selenium powder in another porcelain boat and put them into a tube furnace together. Note that the porcelain boat containing the sample is located downstream of the air flow. Heat at 350°C in an inert atmosphere (Ar) for 90 minutes.

[0073] Step 5: The carbon cloth sample obtained by the gas phase selenization reaction is washed with carbon disulfide, ethanol and deionized water respectively and dried to obtain the self-supporting electrode of the cobalt diselenide metal phase molybdenum disulfide-based in-plane heterogeneous structure.

[0074] Embodiment 6: A method for preparing a zinc diselenide metal phase molybdenum disulfide in-plane heterostructure self-supporting electrode, comprising the following steps:

[0075] Compared with Example 5, zinc nitrate was used to replace cobalt nitrate, and the rest was the same as Example 5.

[0076] Embodiment 7: A method for preparing an iron diselenide metal phase molybdenum disulfide in-plane heterostructure, comprising the following steps:

[0077] Compared with Example 5, cobalt nitrate is replaced by iron nitrate, and the rest is the same as Example 5.

[0078] Embodiment 8: A method for preparing a nickel diselenide metal phase molybdenum disulfide in-plane heterostructure, comprising the following steps:

[0079] Compared with Example 5, cobalt nitrate is replaced by nickel nitrate, and the rest is the same as Example 5.

[0080] Comparative Example 1: A method for preparing a self-supporting electrode of cobalt selenide grown on carbon cloth, comprising the following steps:

[0081] Step 1: Weigh 0.56g of hexahydrate and cobalt nitrate, 0.78g of urea, dissolve in 12ml of deionized water, add 12ml of anhydrous ethanol to the solution, and then add the conductive substrate - carbon cloth (2*2cm 2 ), the conductive substrate solution was placed in a 50 ml reactor, and placed in an oven for hydrothermal reaction at 95° C. for 6 h to obtain a basic cobalt carbonate nanowire array grown on the carbon cloth.

[0082] Step 2: Weigh 1.5 g of sodium sulfide, 0.45 g of thioacetamide, and 1.8 mg of urea, dissolve them in 25 ml of deionized water and stir evenly to form a uniform solution, place the solution in a 50 ml reactor, place the basic cobalt carbonate nanowire array grown on the carbon cloth obtained in the first step in the reactor, and hydroheat in an oven at 200°C for 12 hours.

[0083] Step 3: After the hydrothermal reaction is completed, the carbon cloth is naturally cooled to room temperature, and the carbon cloth is taken out, washed several times with deionized water and ethanol respectively, and vacuum dried to obtain cobalt disulfide loaded on the carbon cloth;

[0084] Step 4: Place the obtained carbon cloth sample in a porcelain boat, and place 200 mg of selenium powder in another porcelain boat and put them into a tube furnace together. Note that the porcelain boat containing the sample is located downstream of the air flow. Heat at 350°C in an inert atmosphere (Ar) for 90 minutes.

[0085] Step 5: The carbon cloth sample obtained by the gas phase selenization reaction is washed with carbon disulfide, ethanol and deionized water respectively and dried to obtain the cobalt diselenide self-supporting electrode.

[0086] Comparative Example 2: A method for preparing a self-supporting electrode of metallic phase molybdenum disulfide grown on carbon cloth, comprising the following steps:

[0087] Step 1: Weigh 90 mg of molybdenum trioxide, 1.5 g of sodium sulfide, 0.45 g of thioacetamide, and 1.8 g of urea, dissolve them in 25 ml of deionized water and stir evenly to form a uniform solution, place the solution in a 50 ml reactor, place the basic cobalt carbonate nanowire array grown on the carbon cloth obtained in the first step in the reactor, and hydroheat in an oven at 200 ° C for 12 hours.

[0088] Step 2: After the hydrothermal reaction is completed, the carbon cloth is naturally cooled to room temperature, and the carbon cloth is taken out, washed several times with deionized water and ethanol respectively, and vacuum dried to obtain a metal phase molybdenum disulfide in-plane heterogeneous structure supported on the carbon cloth;

[0089] Comparative Example 3: A method for preparing a self-supporting electrode having an out-of-plane heterostructure of cobalt diselenide metal phase and molybdenum disulfide grown on carbon cloth, comprising the following steps:

[0090] Step 1: Repeat Comparative Example 2 to obtain a metal phase molybdenum disulfide self-supporting electrode;

[0091] Step 2: Cobalt hydroxide nanoparticles are deposited on metallic phase MoS2 nanosheets. In a standard three-electrode electrochemical cell, the cobalt hydroxide metallic phase MoS2 out-of-plane heterostructure grown on carbon cloth is obtained by chronoamperometry. The obtained metallic phase MoS2 self-supporting electrode, graphite rod and Ag / AgCl (saturated KCl solution) are used as working electrode, counter electrode and reference electrode respectively. A 0.1M aqueous solution of cobalt nitrate is used as the electrolyte. The reaction potential is -1.5V and the reaction time is 120s.

[0092] Step 3: After electrodeposition, the electrode was rinsed several times with deionized water and dried at 40 °C overnight;

[0093] Step 4: Place the carbon cloth sample in a porcelain boat, and place 200 mg of selenium powder in another porcelain boat and place them together in a tube furnace. Note that the porcelain boat containing the sample is located downstream of the air flow. Heat at 350°C in an inert atmosphere (Ar) for 90 minutes.

[0094] Step 5: The carbon cloth samples obtained by the gas phase selenization reaction are washed with carbon disulfide, ethanol and deionized water respectively and dried to obtain the self-supporting electrode of the cobalt diselenide metal phase molybdenum disulfide out-of-plane heterostructure.

[0095] Test results:

[0096] The self-supporting electrode of the cobalt diselenide metal phase molybdenum disulfide in-plane heterostructure prepared in Example 5 was characterized by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). Figure 1 SEM images of the self-supporting electrode with in-plane heterostructure of cobalt diselenide metal phase and molybdenum disulfide are shown at different magnifications. Figure 2 HRTEM image of the in-plane heterostructure of molybdenum disulfide corresponding to the cobalt diselenide metallic phase is shown.

[0097] The self-supporting electrode of the cobalt diselenide metal phase molybdenum disulfide in-plane heterostructure prepared in Example 5, the cobalt diselenide self-supporting electrode of Comparative Example 1, the metal phase molybdenum disulfide self-supporting electrode of Comparative Example 2, and the cobalt diselenide metal phase molybdenum disulfide out-of-plane heterostructure self-supporting electrode of Comparative Example 3 were used as working electrodes in a 1M KOH solution for electrochemical hydrogen evolution reaction. Figure 3 Corresponding to these self-supporting electrodes linear sweep voltammetry curves. Figure 3 It can be seen that the self-supporting electrode of the cobalt diselenide metal phase and molybdenum disulfide in-plane heterostructure exhibits excellent catalytic activity in alkaline solution, with a charge transfer rate of 10 mA / cm 2The overpotential corresponding to the current density is the evaluation parameter, and the overpotential corresponding to the self-supporting electrode of the cobalt diselenide metal phase molybdenum disulfide in-plane heterogeneous structure is 48mV. This performance is comparable to the performance of the currently reported advanced water electrolysis hydrogen evolution catalyst. 2 / CC、CoSe 2 / 1T-MoS 2 / CC、1T-MoS 2 / CC and CoSe 2 @1T-MoS 2 / CC are cobalt diselenide, cobalt diselenide / metallic phase MoS2 out-of-plane heterostructure, metal phase MoS2 and cobalt diselenide / metallic phase MoS2 in-plane heterostructure self-supporting electrodes, respectively.

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure, characterized in that: The following steps are involved: Step 1: preparing a transition metal basic carbonate precursor, specifically dissolving a transition metal salt and an appropriate amount of a nucleating agent in a mixed solution of water and ethanol, loading the mixture into a closed reactor, and synthesizing the basic carbonate by a hydrothermal method; the hydrothermal reaction temperature is 90-140° C., and the reaction time is 5-12 hours; Step 2: preparing a transition metal sulfide / metal phase molybdenum disulfide in-plane heterostructure, specifically weighing the transition metal basic carbonate prepared in step 1, adding molybdenum trioxide, a sulfur source, and an appropriate amount of a reducing agent according to a proportion, and adding an appropriate amount of water to mix evenly, placing the mixed solution in a closed reactor for hydrothermal reaction, the reaction temperature is 180-240°C, and the reaction time is 8-24h; Step 3: preparing a transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure, specifically placing the transition metal sulfide / metal phase molybdenum disulfide in-plane heterostructure obtained in step 2 in a selenium vapor atmosphere for a vapor phase selenization reaction, wherein the reaction temperature of the vapor phase selenization reaction is 300-400° C. and the reaction time is 1-3 hours; Step 4: The transition metal selenide / metallic phase molybdenum disulfide powder obtained by the gas phase selenization reaction in step 3 is washed with carbon disulfide, ethanol and deionized water respectively and dried to obtain a sample of a transition metal selenide / metallic phase molybdenum disulfide in-plane heterostructure.

2. The method for preparing the transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure according to claim 1, characterized in that: In step 1, the transition metal basic carbonate precursor includes but is not limited to basic iron carbonate, basic cobalt carbonate, basic nickel carbonate, and basic zinc carbonate; The nucleating agent includes but is not limited to urea and ammonium fluoride; The sulfur source is selected from one or more of thioacetamide or sodium sulfide; The reducing agent is any one or more of urea or hydrazine hydrate; The ratio of water to ethanol is 1:1; The ratio of the number of molybdenum atoms in the molybdenum trioxide to the number of sulfur atoms in the sulfur source is 1:5-40.

3. The method for preparing the transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure according to claim 2, characterized in that: In the step 3, the selenium vapor atmosphere is formed by decomposing selenium powder at high temperature in an inert atmosphere, the inert atmosphere includes pure nitrogen and argon, and the atmosphere should be higher than atmospheric pressure during the reaction; The carbon disulfide is used to wash away the elemental selenium on the surface of the sample; the mass ratio of the selenium powder to the transition metal sulfide metal phase molybdenum disulfide in-plane heterogeneous structure powder is 40-100:

1.

4. The method for preparing the transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure according to claim 2, characterized in that: In the step three, the temperature of the gas phase selenization reaction is 350°C.

5. A self-supporting electrode, characterized in that: The transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure obtained by the preparation method of the transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure described in any one of claims 1 to 4 above, the self-supporting electrode is formed by growing an array of transition metal selenide metal phase molybdenum disulfide in-plane heterostructure nanosheets on a conductive substrate.

6. The self-supporting electrode according to claim 5, characterized in that: The method for preparing the self-supporting electrode comprises the following specific steps: Step 1: Preparation of transition metal basic carbonate precursor, specifically dissolving transition metal salt and an appropriate amount of nucleating agent in a mixed solution of water and ethanol, loading into a closed reactor, and adding a conductive substrate to the mixed solution, preparing basic carbonate grown on the conductive substrate by a hydrothermal method; the conductive substrate includes pretreated carbon cloth, titanium sheet and nickel foam; the hydrothermal reaction temperature is 90-140°C, and the reaction time is 5-12h; Step 2: preparing a transition metal sulfide / metal phase molybdenum disulfide in-plane heterostructure, specifically, molybdenum trioxide, a sulfur source, and an appropriate amount of a reducing agent, and adding an appropriate amount of water to mix evenly, and placing the conductive substrate containing the basic carbonate nanowire array prepared in step 1 in the mixed solution, and placing the mixed solution in a closed reactor for hydrothermal reaction to obtain a transition metal sulfide / metal phase molybdenum disulfide in-plane heterostructure grown on the conductive substrate, the reaction temperature is 180-240°C, and the reaction time is 8-24h; Step 3: preparing a transition metal selenide / metal phase MoS2 in-plane heterostructure, specifically placing the conductive substrate on which the transition metal sulfide / metal phase MoS2 in-plane heterostructure is grown obtained in step 2 under a selenium vapor atmosphere for a vapor phase selenization reaction, wherein the reaction temperature of the vapor phase selenization reaction is 300-400° C. and the reaction time is 1-3 hours; Step 4: The conductive substrate sample obtained after the gas phase selenization reaction is washed with carbon disulfide, ethanol and deionized water respectively and dried to obtain the self-supporting electrode of the transition metal selenide / metal phase molybdenum disulfide in-plane heterostructure.

7. An application of a self-supporting electrode, based on the self-supporting electrode according to claim 6, characterized in that: The application is to use the self-supporting electrode for electrocatalytic hydrogen evolution reaction.

Images