A platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite, a preparation method and application thereof

Abstract

The application discloses a platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite material, a preparation method and application. The application first uses a metal molybdenum salt and a complexing agent as raw materials to prepare a Mo2C / MoO2 base material containing a heterojunction, then loads PtNi on the Mo2C / MoO2 base material to prepare the platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite material. The MoO2 / Mo2C nanomaterial carrier well anchors the PtNi alloy, further improves the catalytic stability of the material, and the electronic coupling and interface synergistic effect provided by the heterojunction can enhance the reactivity of the active sites, so as to maximize the catalytic performance of the material, and further reduce the hydrogen production application cost under an acid condition. Experimental results show that the platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite material has the advantages of high catalytic activity, excellent stability and the like as a hydrogen production electrocatalyst of an acid electrolyte, and therefore has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrocatalytic hydrogen evolution catalyst materials, and particularly relates to a platinum-nickel supported molybdenum carbide / molybdenum dioxide nanocomposite, a preparation method and application. BACKGROUND

[0002] Hydrogen (H2) is widely concerned due to its environmental protection, high heat value and power density. The raw material source for water electrolysis to produce hydrogen is abundant, and high-purity hydrogen is produced by using electricity generated by renewable energy, which is simple, efficient and easy to popularize, and is a sustainable and green approach. The hydrogen evolution reaction (HER) is an important step for preparing high-purity hydrogen, however, high energy consumption and slow kinetics hinder its development. It is important to design efficient electrocatalysts to improve the kinetics of catalytic reactions, and most of the currently developed HER catalysts perform well in alkaline conditions, but perform poorly in acidic conditions, especially long-term durability.

[0003] As the most advanced HER catalysts, Pt-based noble metal materials cannot be used on a large scale due to the shortage of Pt reserves and high price. Therefore, it is of great significance to develop low-Pt supported electrocatalysts with high intrinsic catalytic activity.

[0004] Loading Pt on a suitable support is an ideal way to reduce costs, which not only can effectively reduce the content of Pt, but also can avoid the agglomeration of Pt nanoparticles. The properties of the support play an important role in the activity and stability of the catalyst. Therefore, it is crucial to choose a suitable support. Studies have found that transition metal oxides and carbides (such as MoO2 and Mo2C) have their unique electronic structure, and have superior activity and stability for HER. However, the low catalytic efficiency or poor stability leads to unsatisfactory hydrogen evolution performance of single-phase MoO2 and Mo2C. By using a heterostructure coupling strategy, the intrinsic catalytic performance can be enhanced by optimizing the electronic structure of the active sites. The heterojunction formed between the two components can optimize the electronic structure, and the electronic coupling and interface synergistic effect can enhance the reactivity of the active sites. Although such catalysts have excellent catalytic activity, their activity is not sufficient for industrial applications, especially the stability under large current density in acidic conditions. Therefore, it is necessary to find a simple and low-cost process to obtain a small amount of Pt-loaded heterojunction material and apply it to catalyze water electrolysis to produce hydrogen under large current density in acidic conditions, which will provide more scientific basis and technical support for the development and application of the process of water electrolysis to produce hydrogen. SUMMARY

[0005] In view of the problems in the background art, the present application aims to provide a platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite material, a preparation method and application, wherein the raw materials used in the preparation method are inexpensive, the process and equipment are simple, the production cost is low, and the large-scale production is easy to realize, and the obtained platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite material has excellent electrocatalytic performance.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] The first aspect of the present application provides a preparation method of a platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite material, comprising the following steps:

[0008] S1, preparation of a Mo2C / MoO2 base material containing a heterojunction:

[0009] S11, dissolving a metal molybdenum salt and a complexing agent in deionized water, adjusting the pH to 4-5, reacting at a certain temperature, purifying, and drying;

[0010] S12, pyrolysis treatment of the dried reaction product to obtain a Mo2C / MoO2 base material containing a heterojunction as a carrier;

[0011] S2, preparation of a platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite material:

[0012] dissolving the Mo2C / MoO2 base material containing the heterojunction in water, adding a platinum source, a nickel source, a surfactant, a reducing solvent and an acid, mixing, and reacting to obtain a platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite material, which is hereinafter abbreviated as PtNi-Mo2C / MoO2 composite material.

[0013] Preferably, in step S11, the amount ratio of the metal molybdenum salt, the complexing agent and the deionized water is 2-5 g:1-3 mL:25-40 mL.

[0014] Preferably, in step S11, the reaction temperature is 30-80℃, and the reaction time is 2-3h.

[0015] Preferably, in step S11, the purification includes: vacuum suction filtration of the reaction product, and washing treatment, wherein the washing is performed by sequentially rinsing with water and ethanol.

[0016] Preferably, in step S11, the drying temperature is 30-100℃.

[0017] Preferably, in step S12, the pyrolysis treatment is at 600-650℃, and the pyrolysis time is 1-2h.

[0018] Preferably, in step S2, the reaction temperature is 50-90℃, and the reaction time is 5-10h.

[0019] Preferably, in step S2, the amount of the platinum source, the nickel source, the surfactant, the Mo2C / MoO2 substrate material containing a heterojunction, the reducing solvent, the acid and the deionized water is 5-35mg: 5-35mg; 30-50mg: 100mg: 10μL: 25μL: 20mL.

[0020] Preferably, in step S1, the acid used for adjusting pH is any one of dilute hydrochloric acid, dilute sulfuric acid and acetic acid, and is further preferably dilute hydrochloric acid with a concentration of 1-5mol / L.

[0021] Preferably, in step S1, the metal molybdenum salt is ammonium heptamolybdate tetrahydrate, and the complexing agent is ethylenediamine.

[0022] Preferably, in step S2, the platinum source is potassium chloroplatinate, the acid is hydrochloric acid with a concentration of 6-10mol / L, the nickel source is nickel chloride hexahydrate, the surfactant is polyoxyethylene polyoxypropylene ether, and the reducing solvent is ethanol.

[0023] The second aspect of the present application provides a platinum-nickel supported Mo2C / MoO2 nanocomposite prepared by the above preparation method.

[0024] Preferably, the Mo2C / MoO2 substrate material containing a heterojunction is in a nanorod structure.

[0025] Preferably, the platinum-nickel supported Mo2C / MoO2 nanocomposite is in a nanorod structure.

[0026] Preferably, the platinum-nickel supported Mo2C / MoO2 nanocomposite is a nanorod with a diameter of 100-200nm, and the platinum-nickel alloy particles with an average size of 3-10nm are uniformly distributed on the Mo2C / MoO2 nanorod.

[0027] Preferably, the content of Pt in the platinum-nickel supported Mo2C / MoO2 nanocomposite is less than 1wt%.

[0028] The third aspect of the present application provides an application of the above platinum-nickel supported Mo2C / MoO2 nanocomposite as a catalyst in catalytic hydrogen evolution in water electrolysis.

[0029] The present application has the following beneficial effects:

[0030] (1) The application first uses a metal molybdenum salt and a complexing agent as raw materials to prepare a Mo2C / MoO2 base material containing a heterojunction, and then loads PtNi on the Mo2C / MoO2 base material to prepare a platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite. Among them, the MoO2 / Mo2C base material can well anchor the PtNi alloy as a carrier, which can further improve the catalytic stability of the material, and the generation of the heterojunction in the molybdenum carbide / molybdenum dioxide (Mo2C / MoO2) base material can enhance the reactivity of the active sites through the electronic coupling and interface synergistic effect provided by the heterojunction interface, which is conducive to maximizing the performance of the material, while reducing the cost, and further reducing the application cost of hydrogen production under acidic conditions. The experimental results show that the use of the platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite can maximize the use amount of the noble metal Pt, and exhibits excellent electrocatalytic hydrogen evolution performance and stability under acidic (0.5M H2SO4) conditions.

[0031] (2) The preparation method has the characteristics of low cost of raw materials, simple process and equipment, low production cost, easy realization of large-scale industrial production, etc., and therefore has good application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0033] Figure 1 XRD pattern of the PtNi-Mo2C / MoO2 composite material prepared in Example 1 and the Mo2C / MoO2 base material containing a heterojunction;

[0034] Figure 2 SEM images of different regions of the Mo2C / MoO2 base material containing a heterojunction: (a) scale is 1 μm; (b) scale is 1 μm;

[0035] Figure 3 SEM images of different regions of the PtNi-Mo2C / MoO2 composite material prepared in Example 1: (a) scale is 1 μm, (b) scale is 1 μm;

[0036] Figure 4TEM and elemental mapping of the PtNi-Mo2C / MoO2 composite prepared in Example 1: (a) TEM image with a scale bar of 100 nm, (b) TEM image with a scale bar of 20 nm, (c) TEM image with a scale bar of 5 nm, and (d-h) elemental mapping with a scale bar of 50 nm;

[0037] Figure 5 XPS of the PtNi-Mo2C / MoO2 composite prepared in Example 1;

[0038] Figure 6 Electrochemical performance of the PtNi-Mo2C / MoO2 composite prepared in Example 1, and the Mo2C / MoO2 substrate material containing a heterojunction in 0.5 M H2SO4: (a) LSV of the PtNi-Mo2C / MoO2 composite, the Mo2C / MoO2 substrate material in 0.5 M H2SO4; (b) overpotential and Tafel slope of the PtNi-Mo2C / MoO2 composite, the Mo2C / MoO2 substrate material in 0.5 M H2SO4;

[0039] Figure 7 Electrochemical performance of the PtNi-Mo2C / MoO2 composite, the Pt-Mo2C / MoO2 composite, and the Ni-Mo2C / MoO2 composite prepared in Example 1 and Comparative Examples 1-2 in 0.5 M H2SO4: (a) LSV of the PtNi-Mo2C / MoO2 composite, the Pt-Mo2C / MoO2 composite, and the Ni-Mo2C / MoO2 composite in 0.5 M H2SO4; (b) overpotential and Tafel slope of the PtNi-Mo2C / MoO2 composite in 0.5 M H2SO4 at 1 A cm -2 Long-term stability test at a current density;

[0040] Figure 8 Comparison of current density and mass activity of the PtNi-Mo2C / MoO2 composite prepared in Example 1 and a commercial Pt / C in 0.5 M H2SO4. DETAILED DESCRIPTION

[0041] In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular architectures, technologies, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application can be practiced in other embodiments that depart from these specific details.

[0042] Example 1

[0043] A method for preparing a platinum-nickel supported molybdenum carbide / molybdenum dioxide nanocomposite, comprising the following steps:

[0044] (1) Preparation of Mo2C / MoO2 substrate material containing heterojunction as carrier: 2.48 g of ammonium heptamolybdate tetrahydrate and 1778 μL of ethylenediamine were dissolved in 30 mL of distilled water, and then 1 mol / L hydrochloric acid was added dropwise to the solution under stirring to adjust the pH value to 4, and a white precipitate gradually separated out during the adjustment process. Then, the adjusted solution was placed in a water bath at 50°C and slowly stirred for 2 h, and then the white precipitate product of the reaction was washed by vacuum filtration. During the washing process, 500 mL of distilled water was used for flushing, and then 100 mL of ethanol was used for flushing. Subsequently, the obtained white precipitate product was dried in an oven at 70°C for 3 h, and finally the dried white precipitate product was placed in a tube furnace, and the temperature was raised to 650°C at a rate of 5°C / min under the flow of argon / hydrogen (hydrogen accounts for 10%) at 20 mL / min, and was kept for 2 h, and then was naturally cooled to obtain the Mo2C / MoO2 substrate material containing heterojunction.

[0045] (2) Preparation of platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite: First, 0.015 mmol of potassium chloroplatinate, 0.03 mmol of nickel chloride hexahydrate and 30 mg of polyoxyethylene polyoxypropylene ether were dissolved in 20 mL of deionized water, and then 25 μL of 6M hydrochloric acid, 10 μL of ethanol and 85 mg of Mo2C / MoO2 were added, and ultrasonic dispersion was performed for 30 min, and then the mixture was placed in a 50°C water bath and stirred vigorously for 6 h. After centrifugation, the precipitate was washed with deionized water and anhydrous ethanol for several times, and was dried at 70°C for 10 h to obtain the platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite, which is denoted as PtNi-Mo2C / MoO2 composite material.

[0046] Example 2

[0047] A method for preparing a platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite, comprising the following steps:

[0048] (1) Preparation of Mo2C / MoO2 substrate material containing heterojunction as carrier: 2.48 g of ammonium heptamolybdate tetrahydrate and 1778 μL of ethylenediamine were dissolved in 30 mL of distilled water, and then 2 mol / L hydrochloric acid was added dropwise to the solution under stirring to adjust the pH value to 5, and a white precipitate gradually separated out during the adjustment process. Then, the adjusted solution was placed in a 30 °C water bath for slow stirring reaction for 2 h, and then the white precipitate product of the reaction was cleaned by vacuum filtration, and during the washing process, 500 mL of distilled water was used for washing, and then 100 mL of ethanol was used for washing, and then the obtained white precipitate product was dried in an oven at 30 °C for 3 h, and finally the dried white precipitate product was placed in a tube furnace, and under the flow of argon / hydrogen (hydrogen accounts for 10%) of 20 mL / min, the temperature was raised at a rate of 5 °C / min to 650 °C and kept for 2 h, and then naturally cooled to obtain the Mo2C / MoO2 substrate material containing heterojunction.

[0049] (2) Preparation of platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite by loading platinum-nickel alloy on the Mo2C / MoO2 substrate material containing heterojunction: First, 0.015 mmol of potassium chloroplatinate, 0.03 mmol of nickel chloride hexahydrate and 30 mg of polyoxyethylene polyoxypropylene ether were dissolved in 20 mL of deionized water, and then 25 μL of 7M hydrochloric acid, 10 μL of ethanol and 85 mg of Mo2C / MoO2 substrate material containing heterojunction were added, and ultrasonic dispersion was performed for 30 min, and then the mixture was placed in a 50 °C water bath for vigorous stirring reaction for 8 h, and then centrifugation was performed to obtain a precipitate, which was washed with deionized water and anhydrous ethanol for several times, and then dried at 70 °C for 10 h to obtain the platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite, which is denoted as PtNi-Mo2C / MoO2 composite material.

[0050] Example 3

[0051] A method for preparing a platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite, comprising the following steps:

[0052] (1) Preparation of Mo2C / MoO2 substrate material containing heterojunction as carrier: 2.48 g of ammonium heptamolybdate tetrahydrate and 1778 μL of ethylenediamine were dissolved in 30 mL of distilled water, and then 3 mol / L hydrochloric acid was added dropwise to the solution under stirring to adjust the pH value to 4, and a white precipitate gradually separated out during the adjustment process. Then, the adjusted solution was placed in a water bath at 80°C and slowly stirred for 2 h, and then the white precipitate product of the reaction was cleaned by vacuum filtration. During the washing process, 500 mL of distilled water was used for washing, and then 100 mL of ethanol was used for washing. Subsequently, the obtained white precipitate product was dried in an oven at 50°C for 3 h, and finally the dried white precipitate product was placed in a tube furnace, and the temperature was raised to 650°C at a rate of 5°C / min under the flow of argon / hydrogen (hydrogen accounts for 10%) at 20 mL / min, and then kept for 1 h, and then naturally cooled to obtain the Mo2C / MoO2 substrate material containing heterojunction.

[0053] (2) Preparation of platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite: First, 0.015 mmol of potassium chloroplatinate, 0.03 mmol of nickel chloride hexahydrate and 30 mg of polyoxyethylene polyoxypropylene ether were dissolved in 20 mL of deionized water, and then 25 μL of 8M hydrochloric acid, 10 μL of ethanol and 85 mg of Mo2C / MoO2 were added, and ultrasonic dispersion was performed for 30 min, and then the mixture was placed in a 50°C water bath and stirred vigorously for 10 h. Centrifugation was performed to obtain a precipitate, which was washed with deionized water and anhydrous ethanol for several times, and then dried at 70°C for 10 h to obtain the platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite, which is denoted as PtNi-Mo2C / MoO2 composite material.

[0054] Example 4

[0055] A method for preparing a platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite, comprising the following steps:

[0056] (1) Preparation of Mo2C / MoO2 substrate material containing heterojunction as carrier: 2.48 g of ammonium heptamolybdate tetrahydrate and 1778 μL of ethylenediamine were dissolved in 30 mL of distilled water, and then 4 mol / L hydrochloric acid was added dropwise to the solution under stirring to adjust the pH value to 4, and a white precipitate gradually separated out during the adjustment process. Then, the adjusted solution was placed in a 50°C water bath for slow stirring reaction for 3 h, and then the white precipitate product of the reaction was cleaned by vacuum filtration, and during the washing process, 500 mL of distilled water was used for washing, and then 100 mL of ethanol was used for washing, and then the obtained white precipitate product was dried in an oven at 100°C for 3 h, and finally the dried white precipitate product was placed in a tube furnace, and under the flow of argon / hydrogen (hydrogen accounts for 10%) of 20 mL / min, the temperature was raised at a rate of 5°C / min to 650°C and kept for 2 h, and then naturally cooled to obtain the Mo2C / MoO2 substrate material containing heterojunction.

[0057] (2) Preparation of platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite: First, 0.015 mmol of potassium chloroplatinate, 0.03 mmol of nickel chloride hexahydrate and 30 mg of polyoxyethylene polyoxypropylene ether were dissolved in 20 mL of deionized water, and then 25 μL of 9M hydrochloric acid, 10 μL of ethanol and 85 mg of Mo2C / MoO2 were added, and ultrasonic dispersion was performed for 30 min, and then it was placed in a 70°C water bath for vigorous stirring reaction for 6 h, and then centrifugation was performed to obtain the precipitate, which was washed with deionized water and anhydrous ethanol for several times, and then dried at 70°C for 10 h to obtain the platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite, which is denoted as PtNi-Mo2C / MoO2 composite material.

[0058] Example 5

[0059] A method for preparing a platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite, comprising the following steps:

[0060] (1) Preparation of Mo2C / MoO2 substrate material containing heterojunction as carrier: 2.48 g of ammonium heptamolybdate tetrahydrate and 1778 μL of ethylenediamine were dissolved in 30 mL of distilled water, and then 5 mol / L hydrochloric acid was added dropwise to the solution under stirring to adjust the pH value to 4, and a white precipitate gradually separated out during the adjustment process. Then, the adjusted solution was placed in a 50°C water bath for slow stirring reaction for 2 h, and then the white precipitate product of the reaction was cleaned by vacuum filtration, and during the washing process, it was first washed with 500 mL of distilled water, and then washed with 100 mL of ethanol, and then the obtained white precipitate product was dried in an oven at 50°C for 3 h, and finally the dried white precipitate product was placed in a tube furnace, and under the flow of argon / hydrogen (hydrogen accounts for 10%) of 20 mL / min, the temperature was raised at a rate of 5°C / min to 600°C and kept for 2 h, and then naturally cooled to obtain the Mo2C / MoO2 substrate material containing heterojunction.

[0061] (2) Preparation of platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite by loading platinum-nickel alloy on Mo2C / MoO2 substrate material containing heterojunction: First, 0.015 mmol of potassium chloroplatinate, 0.03 mmol of nickel chloride hexahydrate and 30 mg of polyoxyethylene polyoxypropylene ether were dissolved in 20 mL of deionized water, and then 25 μL of 10M hydrochloric acid, 10 μL of ethanol and 85 mg of Mo2C / MoO2 were added, and ultrasonic dispersion was carried out for 30 min, and then it was placed in a 90°C water bath for vigorous stirring reaction for 6 h, and then centrifugation was carried out to obtain the precipitate, which was washed with deionized water and anhydrous ethanol for several times, and then dried at 70°C for 10 h to obtain the platinum-nickel loaded molybdenum carbide / molybdenum dioxide nanocomposite, which is denoted as PtNi-Mo2C / MoO2 composite material.

[0062] Comparative Example 1

[0063] A method for preparing a platinum loaded molybdenum carbide / molybdenum dioxide nanocomposite, comprising the following steps:

[0064] (1) Preparation of Mo2C / MoO2 substrate material containing heterojunction as carrier: 2.48 g of ammonium heptamolybdate tetrahydrate and 1778 μL of ethylenediamine were dissolved in 30 mL of distilled water, and then 1 M hydrochloric acid was added dropwise to the solution under stirring to adjust the pH value of the solution to about 4-5, and a white precipitate gradually separated out during the adjustment. Then the adjusted solution was placed in a water bath at 50°C and slowly stirred for 2 h. Subsequently, the white precipitate product of the reaction was cleaned by vacuum filtration, and during the washing process, it was first washed with 500 mL of distilled water, then washed with 100 mL of ethanol, and then the obtained white precipitate product was dried in an oven at 70°C for 3 h. Finally, the dried white precipitate product was placed in a tube furnace, and under the flow of argon / hydrogen (hydrogen accounts for 10%) at 20 mL / min, the temperature was raised at a rate of 5°C / min to 650°C and maintained for 2 h, and then naturally cooled, to obtain the Mo2C / MoO2 substrate material containing heterojunction.

[0065] (2) Preparation of platinum-loaded molybdenum carbide / molybdenum dioxide nanocomposite on the Mo2C / MoO2 carrier containing heterojunction: First, 0.015 mmol of potassium chloroplatinate and 30 mg of polyoxyethylene polyoxypropylene ether were dissolved in 20 mL of deionized water, and then 25 μL of 6 M hydrochloric acid, 10 μL of ethanol and 85 mg of Mo2C / MoO2 were added and ultrasonically dispersed for 30 min. Then it was placed in a 50°C water bath and stirred vigorously for 6 hours, and then the precipitate was obtained by centrifugation, washed with deionized water and anhydrous ethanol for several times, and dried at 70°C for 10 h to obtain the platinum-loaded molybdenum carbide / molybdenum dioxide nanocomposite, denoted as Pt-Mo2C / MoO2.

[0066] Comparative Example 2

[0067] A method for preparing a nickel-loaded molybdenum carbide / molybdenum dioxide nanocomposite, comprising the following steps:

[0068] (1) Preparation of Mo2C / MoO2 matrix material containing heterojunction: 2.48 g of ammonium heptamolybdate tetrahydrate and 1778 μL of ethylenediamine were dissolved in 30 mL of distilled water. Then, 1 mol / L hydrochloric acid was added dropwise to the solution under stirring to adjust the pH value to about 4-5. During the adjustment process, a white precipitate gradually precipitated. The adjusted solution was then placed in a water bath at 50 °C and stirred slowly for 2 h. The white precipitate was then washed by vacuum filtration. During the washing process, the product was first rinsed with 500 mL of distilled water and then rinsed with 100 mL of ethanol. The resulting white precipitate was then dried in an oven at 70 °C for 3 h. Finally, the dried white precipitate was placed in a tube furnace and heated to 650 °C for 2 h under an argon / hydrogen (hydrogen accounting for 10%) gas flow at a rate of 5 °C / min. The temperature was then naturally cooled to obtain the Mo2C / MoO2 matrix material containing heterojunction.

[0069] (2) Nickel-loaded molybdenum carbide / molybdenum dioxide nanocomposite material was prepared on a Mo2C / MoO2 matrix material containing heterojunction: First, 0.015 mmol potassium chloroplatinate, 0.03 mmol nickel chloride hexahydrate and 30 mg polyoxyethylene polyoxypropylene ether were dissolved in 20 mL deionized water. Then, 25 μL 6M hydrochloric acid, 10 μL ethanol and 85 mg Mo2C / MoO2 were added and ultrasonically dispersed for 30 min. Then, it was placed in a 50 °C water bath and stirred vigorously for 6 hours. Subsequently, the precipitate was obtained by centrifugation, washed repeatedly with deionized water and anhydrous ethanol, and dried at 70 °C for 10 h to obtain nickel-loaded molybdenum carbide / molybdenum dioxide nanocomposite material, denoted as Ni-Mo2C / MoO2.

[0070] The PtNi-Mo2C / MoO2 composite material prepared in Example 1 and the Mo2C / MoO2 substrate material containing heterojunction were characterized by XRD. The characterization results are as follows: Figure 1 As shown.

[0071] Depend on Figure 1 The results showed obvious crystal diffraction peaks. The Mo2C / MoO2 substrate material containing the heterojunction corresponded to the diffraction peaks of Mo2C (JCPDS no. 15-0457) and MoO2 (JCPDS no. 32-0676). In the PtNi-Mo2C / MoO2 composite material obtained after loading the PtNi alloy, weak PtNi alloy diffraction peaks were observed, and the overall peak intensity was weak, which is due to the low Pt content. ICP testing revealed that the Pt content in the PtNi-Mo2C / MoO2 composite material prepared in Example 1 was 0.6 wt%, and no Ni diffraction peaks were observed. This result indicates that PtNi is loaded in the form of an alloy onto the Mo2C / MoO2 substrate material containing the heterojunction.

[0072] The PtNi-Mo2C / MoO2 composite material prepared in Example 1 and the Mo2C / MoO2 base material containing heterojunction were characterized to obtain SEM images, TEM images and XPS spectra, and the specific results are shown in Figures 2-5 .

[0073] From Figure 2 It can be observed that the Mo2C / MoO2 base material containing heterojunction has a nanorod structure as a whole, and the nanorod structure is formed by accumulation of nanoparticles.

[0074] From Figure 3 It can be observed that the PtNi-Mo2C / MoO2 composite material has a nanorod structure, and the overall gap between the nanorods after loading PtNi becomes smaller, which indicates that the PtNi alloy is loaded on the Mo2C / MoO2 base material containing heterojunction.

[0075] From Figure 4 It can be observed that the Mo2C / MoO2 base material containing heterojunction has an interlaced line structure Figure 4 a-c), and clear lattice fringes can be observed, indicating that the PtNi-Mo2C / MoO2 composite material prepared in Example 1 has good crystallinity. In addition, it can be seen from the Mapping images Figure 4 d-h) that the elements Pt, Ni, Mo and C are uniformly distributed, and the PtNi alloy mainly exists in the form of loading on the surface of the Mo2C / MoO2 base material.

[0076] From Figure 5 a, a peak at 71.6 eV can be observed, which is attributed to the metallic Pt of the PtNi-Mo2C / MoO2; a peak at 72.67 eV can be observed, which is attributed to the oxidized Pt; three obvious peaks in the Mo 2p region correspond to Mo3d 5 / 2 and Mo 3d 3 / 2 , respectively, located at 228.7, 229.5 and 231.9 eV, which are attributed to Mo-C Figure 4 b); located at 232.9 and 235.8 eV, which are attributed to Mo-O; three obvious peaks in the O 1s region correspond to Mo-O bond, O vacancy and C=O bond, respectively; due to the low content of Ni, no obvious spectrum peak is measured, which can also be confirmed by the Mapping images of TEM.

[0077] The above characterization data prove that the Mo2C / MoO2 base material containing heterojunction and the PtNi alloy loaded on the Mo2C / MoO2 containing heterojunction, i.e. the PtNi-Mo2C / MoO2 composite material, have been successfully prepared.

[0078] Experimental Example 1

[0079] The PtNi-Mo2C / MoO2 composite material prepared in Example 1, the Mo2C / MoO2 substrate material containing heterojunction, and the Pt-Mo2C / MoO2 prepared in Comparative Examples 1-2 were compared. 2、 Ni-Mo2C / MoO2 and commercially available Pt / C were used as electrocatalysts in water electrolysis for hydrogen production. The specific steps are as follows:

[0080] Preparation of working electrode: 4 mg of electrocatalyst and 80 μL of 5 wt% Nafion solution were dispersed in 1 mL of deionized water / ethanol mixed solution (V / V = 4 / 1) to form a uniform catalyst suspension; 5 μL of the suspension was dropped onto the surface of a glassy carbon electrode (3 mm in diameter), and the working electrode with supported electrocatalyst was prepared after drying at room temperature.

[0081] The electrocatalytic hydrogen evolution performance of the catalyst was tested in a standard three-electrode cell. A glassy carbon electrode (0.5 cm * 0.5 cm * 0.1 cm) loaded with the catalyst was used as the working electrode, a carbon rod as the counter electrode, and Hg / Hg₂SO₄ as the reference electrode. The electrocatalytic hydrogen evolution performance (LSV) was tested in a 0.5 M H₂SO₄ solution (as the electrolyte) at a scan rate of 2 mV·s. -1 The experimental test temperature was 22±2℃. See the detailed results below. Figures 6-8 .

[0082] Depend on Figure 6 a and Figure 6 Results b show that the acidic hydrogen evolution performance of the Mo2C / MoO2 substrate containing a heterojunction is greatly improved after loading the PtNi alloy. This is because the introduction of the Ni source helps to regulate the electronic structure of Pt, forming an electron-rich region of Pt, thereby effectively improving the catalytic hydrogen evolution activity. Furthermore, the interaction between the PtNi alloy and the heterojunction-containing Mo2C / MoO2 substrate as a support after loading helps to improve long-term stability under acidic conditions. Specifically, the stability reaches 10 mA cm⁻¹. -2 The overpotential of the current density decreased from 136mV to 67mV; the Tafel slope decreased from 145mV. -1 Reduced to 22mV dec -1 .

[0083] Depend on Figure 7The results show that the hydrogen evolution performance of Ni-Mo2C / MoO2 is poor, the hydrogen evolution performance of Pt-Mo2C / MoO2 is second, and the hydrogen evolution performance of PtNi-Mo2C / MoO2 is optimal, which is attributed to the strong electronic interaction between Pt and Mo, the addition of Ni can optimize the electronic structure of Pt, form the electron-rich region of Pt, which is beneficial to the reduction of protons and the desorption of intermediates, and the strong electronic interaction and the synergistic effect of the rich Pt electrons make PtNi-Mo2C have ultra-high mass activity and excellent long-term HER stability. Figure 7 The results show that the PtNi-Mo2C / MoO2 composite material prepared by the application can still maintain high stability after 650h of stability test under a large current density of 1A cm -2 The results show that the PtNi-Mo2C / MoO2 composite material prepared by the application can still maintain high stability after 650h of stability test under a large current density of 1A cm

[0084] The results show that the PtNi-Mo2C / MoO2 composite material prepared by the application can still maintain high stability after 650h of stability test under a large current density of 1A cm Figure 8 The results show that the PtNi-Mo2C / MoO2 composite material prepared by the application can still maintain high stability after 650h of stability test under a large current density of 1A cm Figure 8 The results show that the PtNi-Mo2C / MoO2 composite material prepared by the application can still maintain high stability after 650h of stability test under a large current density of 1A cm

[0085] The application is not limited to the above specific embodiments, and various modifications made by those skilled in the art without creative labor, all of which fall within the protection scope of the application.

Claims

1. A method for preparing platinum-nickel supported molybdenum carbide / molybdenum dioxide nanocomposite, characterized in that, The preparation method comprises the following steps: S1, preparation of Mo2C / MoO2 base material containing heterojunction: S11, dissolving metal molybdenum salt and complexing agent in deionized water, adjusting pH to 4-5, reacting at a certain temperature, purifying, and drying; S12, pyrolysis treatment of the dried reaction product to obtain Mo2C / MoO2 base material containing heterojunction; S2, preparation of platinum-nickel loaded Mo2C / MoO2 nanocomposite: Dissolve Mo2C / MoO2 base material containing heterojunction in water, add platinum source, nickel source, surfactant, reducing solvent and acid, mix, and react to obtain platinum-nickel loaded Mo2C / MoO2 nanocomposite.

2. The method for preparing platinum-nickel supported molybdenum carbide / molybdenum dioxide nanocomposite materials according to claim 1, characterized in that, In step S11, the ratio of the amount of metal molybdenum salt, complexing agent and deionized water is 2-5 g: 1-3 mL: 25-40 mL.

3. The method for preparing platinum-nickel supported molybdenum carbide / molybdenum dioxide nanocomposite materials according to claim 1, characterized in that, In step S11, the reaction temperature is 30-80℃, and the reaction time is 2-3 h; the drying temperature is 30-100℃.

4. The method of claim 1, wherein the platinum nickel supported molybdenum carbide / molybdenum dioxide nanocomposite is prepared by the steps of: In step S12, the pyrolysis temperature is 600-650℃, and the pyrolysis time is 1-2 h.

5. The method for preparing platinum-nickel supported molybdenum carbide / molybdenum dioxide nanocomposite materials according to claim 1, characterized in that, In step S2, the reaction temperature is 50-90℃, The reaction time is 5-10 h.

6. The method of claim 1, wherein the platinum nickel supported molybdenum carbide / molybdenum dioxide nanocomposite is prepared by the steps of: In step S2, the amount of platinum source, nickel source, surfactant, Mo2C / MoO2 base material containing heterojunction, reducing solvent, acid and water is 5-35 mg: 5-35 mg; 30-50 mg: 100 mg: 10 μL: 25 μL: 20 mL.

7. The method for preparing platinum-nickel supported molybdenum carbide / molybdenum dioxide nanocomposite materials according to claim 1, characterized in that, In step S11, the metal molybdenum salt is ammonium heptamolybdate tetrahydrate; the complexing agent is ethylenediamine; and the acid used to adjust pH is any one of dilute hydrochloric acid, dilute sulfuric acid and acetic acid.

8. The method of claim 1, wherein the platinum nickel supported molybdenum carbide / molybdenum dioxide nanocomposite is prepared by, In step S2, the platinum source is potassium chloroplatinate; the acid is hydrochloric acid with a concentration of 6-10 mol / L; the nickel source is nickel chloride hexahydrate; the surfactant is polyoxyethylene polyoxypropylene ether; and the reducing solvent is ethanol.

9. A platinum-nickel loaded Mo2C / MoO2 nanocomposite prepared by the preparation method of any one of claims 1-8.

10. Use of the platinum-nickel loaded Mo2C / MoO2 nanocomposite of claim 9 as an electrocatalyst for hydrogen production by electrolysis of water.

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