Preparation method of platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst with high activity and wide pH water electrolysis hydrogen production performance

Abstract

The invention discloses a preparation method of a platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst with high activity and wide pH water electrolysis hydrogen production performance, and belongs to the technical field of new energy materials. A metal-organic compound is used as a precursor, a platinum / tungsten nitride heterostructure is synthesized through a one-step pyrolysis method, and the platinum / tungsten nitride heterostructure is uniformly embedded into the surface of a nanosheet layer of a conductive carbon nanoflower matrix. The Pt-W2N (at) C has excellent electro-catalytic hydrogen evolution performance, shows ultralow overpotential in acidic, alkaline and neutral electrolytes, even has the electrochemical performance obviously superior to that of a commercial platinum-carbon catalyst under high current density, and shows good durability in a long-time stability test; and a new thought is provided for design and development of the low-platinum-loaded HER electrocatalyst.

Description

Technical Field

[0001] The present invention belongs to the technical field of new materials, and more specifically relates to a preparation method of a platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst with high activity and wide pH electrocatalytic hydrogen production performance. Background Art

[0002] With the progress of human science and technology, energy and environmental problems are becoming increasingly severe. Hydrogen, characterized by zero carbon emissions (weight energy density of 143 MJ / kg), and renewable compatibility, has become a strategic solution for achieving carbon neutrality. Electrochemical water splitting, especially when combined with renewable energy, provides an environmentally friendly approach for hydrogen production. However, industrial electrolysis faces inherent limitations, including high ohmic losses and a large overpotential for the hydrogen evolution reaction (HER), mainly due to slow reaction kinetics.

[0003] Platinum and platinum-based nanomaterials are considered the most advanced HER electrocatalysts, with exceptional activity (Tafel slope ≈ 30 mV·dec -1 ) and durability, as well as an optimal hydrogen adsorption free energy close to the thermodynamic potential (ΔG H* ≈ 0 eV). However, the high cost ($38 per gram) and low abundance of Pt-based catalysts severely limit the large-scale application of industrial water electrolysis. Therefore, reducing the usage of precious metals and developing nanomaterials with high catalytic activity per unit mass are of profound significance for promoting a breakthrough in the hydrogen energy industry.

[0004] In recent years, researchers have continued to strive to develop low-Pt-loaded multiphase catalysts to combine economic efficiency, high activity, and stability. The construction of heterointerfaces provides unique advantages for energy storage and conversion, mainly because heterostructures containing different materials can maximize the advantages of each component and make up for its disadvantages. Previous work has shown that interface engineering can significantly promote charge transfer in heterojunctions, highly protect exposed active centers, change the charge density, thereby affecting the adsorption / desorption between active centers and reactants / intermediates, achieving efficient, multifunctional, and diverse electrocatalytic technologies, and having excellent activity in media with a wide pH range.

[0005] Among numerous candidate matrices, transition metal nitrides (TMNs) stand out with their excellent activity and long-term durability. Recently, breakthroughs in Pt-TMN heterostructure design have successfully reconciled the trade-off between high activity and stability. For example, Yang et al. demonstrated an ultralow platinum (0.07 wt.%) electrocatalyst (Pt-Ni@NiMoN) anchored on nickel molybdenum nitride, which exhibits high activity at industrially relevant current densities (400 mA·cm -2) exhibits excellent HER performance under the following conditions, with a minimum overpotential and excellent durability. This achievement is attributed to the strong anchoring effect between Pt and TMN, as well as the optimized ΔG at the heterojunction interface. H* . In particular, tungsten-based nitrides have been widely studied due to their good chemical stability, Pt-like d electron configuration, and excellent electrical conductivity. Therefore, constructing a heterostructure of Pt and tungsten-based nitrides to promote the synergistic effect between the two is expected to improve the performance of electrocatalytic materials while reducing the Pt loading. Summary of the Invention

[0006] An object of the present invention is to provide a method for preparing a platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst with high activity and wide pH electrolytic water hydrogen production performance. The present invention constructs a platinum / tungsten nitride heterostructure with strong interaction by means of Pt-O-W interfacial bonding, and disperses and anchors it on a conductive carrier with a high specific surface area. Through the strong coupling of metallic platinum and tungsten nitride and the synergistic electron interaction at the heterojunction interface, excellent stability and electrocatalytic hydrogen evolution reaction performance in a wide pH range are achieved.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] One of the technical solutions of the present invention: provide a platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst with high activity and wide pH electrolytic water hydrogen production performance, wherein the platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst comprises a carbon nanoflower-shaped conductive carrier and platinum / tungsten nitride heterojunction nanoparticles uniformly loaded on the conductive carrier.

[0009] Another technical solution of the present invention: provide a method for preparing a platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst with high activity and wide pH electrolytic water hydrogen production performance. This method synthesizes a W-PDA precursor through the in-situ coordination polymerization reaction of WO4 2- with DA-HCl; by means of the adsorption impregnation method, an appropriate amount of Pt 2+ substance is accurately anchored on the W-PDA substrate by means of Pt-O-W interfacial bonding; using a one-step pyrolysis method for high-temperature treatment in an argon atmosphere at 800 °C, the inorganic-organic framework is transformed into a nitrogen-doped carbon matrix, and at the same time, the tungsten species are converted into W2N through nitridation, and finally a Pt-W2N@C heterostructure with uniform dispersion and a clear metal-nitride interface is obtained.

[0010] Further, the preparation method includes the following steps:

[0011] Step 1: Synthesis of W-Polydopamine (W-PDA) Precursor: Dissolve 540 mg of dopamine hydrochloride (DA-HCl) in 288 mL of absolute ethanol and stir mechanically or sonicate until completely dissolved. Meanwhile, dissolve 1010 mg of sodium tungstate dihydrate (Na2WO4·2H2O) in 144 mL of deionized water, add 5 mL of ammonia water (NH4OH), and sonicate until completely dissolved. Subsequently, quickly mix the two solutions and magnetically stir at room temperature for 1 hour to allow the polymerization reaction to proceed. Centrifuge the resulting suspension, wash it twice with ethanol, and then dry it in a vacuum oven at 60 °C to obtain dark brown W-PDA powder.

[0012] Step 2: Synthesis of Pt-(W-PDA): Take 100 mg of the above W-PDA powder and disperse it evenly in 100 mL of absolute ethanol, and sonicate for 10 minutes to ensure uniform dispersion. Then, add 4 mL of a 2 μmol / mL ethanol solution of platinum acetylacetonate (C 10 H 14 O4Pt) to the suspension and sonicate for 10 minutes to promote polymerization. Finally, use a rotary evaporator to remove the solvent in a 50 °C water bath to obtain the Pt-(W-PDA) precursor.

[0013] Step 3: Synthesis of Pt-W2N@C Catalyst: Place the synthesized Pt-(W-PDA) powder in a vacuum tube furnace, heat it to 800 °C at a heating rate of 5 °C / min under an Ar protective atmosphere, hold for 2 hours, and then cool naturally to room temperature to finally obtain the Pt-W2N@C catalyst.

[0014] Furthermore, the W-PDA precursor is prepared by the polymerization reaction of sodium tungstate dihydrate and dopamine hydrochloride, and the polymerization time is 0.5 - 1.5 hours.

[0015] Furthermore, the molar ratio of sodium tungstate dihydrate to dopamine hydrochloride is 1:5 - 1:8, and the addition amount of ammonia water is 1 - 3% of the total volume of the mixed solution.

[0016] Furthermore, the Pt-(W-PDA) material is prepared by introducing platinum acetylacetonate into the W-PDA precursor through the adsorption impregnation method. The concentration of the ethanol solution of platinum acetylacetonate is 1 - 3 μmol / mL, and the molar ratio of platinum to tungsten is 1:20 - 1:30, and the ultrasonic polymerization time is 10 - 15 minutes.

[0017] Furthermore, use the Pt-(W-PDA) material to obtain a platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst through Step 3.

[0018] Furthermore, the preparation method obtains a conductive carbon-based transition metal nitride and platinum nanoparticle heterojunction nanomaterial for application in electrocatalytic hydrogen evolution.

[0019] Based on the present invention, the adsorption impregnation method is adopted to precisely regulate the loading of platinum metal species on the W-PDA precursor, and the strong interaction between platinum and tungsten nitride is realized through the Pt-O-W interfacial bond, avoiding the problems of random distribution and weak binding of metal particles in the traditional loading method. Through one-step pyrolysis treatment at high temperature in an inert atmosphere, the formation of the carbon matrix, the nitridation of tungsten species, and the construction of the Pt-W2N heterojunction interface are completed synchronously, simplifying the process flow and ensuring the structural uniformity and stability of the material.

[0020] Aiming at the problems of easy agglomeration of noble metal nanoparticles and weak binding force with the carrier, the present invention uses carbon nanoflowers with a high specific surface area as the conductive carrier. Its three-dimensional cross-nanosheet structure not only provides a large number of anchoring sites, but also effectively inhibits the migration and agglomeration of platinum and tungsten nitride nanoparticles during high-temperature treatment through a certain degree of spatial confinement effect, significantly improving the dispersion and utilization rate of active sites. Tungsten nitride, as a transition metal nitride, forms strong electron coupling with platinum nanoparticles due to its platinum-like d-electron characteristics, synergistically optimizing the hydrogen adsorption free energy (ΔG H* ), thus realizing an efficient hydrogen evolution reaction in a wide pH range. In addition, the high conductivity and mechanical stability of the carbon nanoflower matrix further enhance the durability of the catalyst under long-term high-current conditions, solving the problems of easy corrosion and activity decay of traditional catalysts in acidic or alkaline media.

[0021] By constructing a heterostructure and its synergistic effect with the carrier, the present invention not only reduces the platinum loading amount, but also realizes the high activity and high stability of the catalyst under wide pH conditions, providing an innovative solution for large-scale preparation of low-cost and high-performance electrolytic water hydrogen production catalysts.

[0022] The present invention provides a new strategy for synthesizing high-performance electrocatalytic hydrogen evolution catalyst materials, which has the following significant advantages: ① The Pt-W2N@C composite material formed by the synergistic regulation of platinum nanoparticles and tungsten nitride can construct an atomically dispersed Pt-W2N heterojunction interface, significantly increasing the density of active sites; ② The coupling of the nanosheets of the conductive carbon nanoflower matrix and the Pt-W2N heterostructure ensures the uniform dispersion of nanoparticles, effectively inhibiting the agglomeration phenomenon during high-temperature treatment, and at the same time enhancing the mechanical binding force between the material and the substrate, making it maintain a stable structure under long-term high-current conditions; ③ This method is based on one-step pyrolysis, with a simple process, high repeatability, and easy to scale up production, laying a foundation for large-scale preparation of low-platinum and high-efficiency catalysts.

[0023] Compared with the preparation methods of traditional supported catalysts, this strategy has two major breakthroughs: ① By a simple one-step pyrolysis method, a Pt-W2N heterostructure uniformly dispersed on the surface of conductive carbon nanoflower sheets is formed, which can significantly improve its HER electrocatalytic activity; ② The unique three-dimensional cross-nanosheet structure of the carbon nanoflower matrix not only provides a firm substrate structure and a high specific surface area, but also can stabilize the heterojunction nanoparticles through strong coupling at the interface, avoiding corrosion and activity decay in acidic / alkaline media. In summary, this method provides an innovative solution for the development of hydrogen evolution catalysts with wide pH applicability, high stability, and low cost, and has important practical value for promoting the large-scale production of green hydrogen.

[0024] The third technical solution of the present invention: Provide an application of the above platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst as an electrode modification material in the preparation of an electrocatalytic reaction electrode.

[0025] Furthermore, the electrocatalytic reaction includes water electrolysis for hydrogen production.

[0026] The fourth technical solution of the present invention: Provide an electrode for water electrolysis for hydrogen production, and the active component of the electrode includes the above platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst.

[0027] The fifth technical solution of the present invention: Provide a method for water electrolysis for hydrogen production, and the method uses the above electrode as a working electrode.

[0028] The present invention discloses the following technical effects:

[0029] The platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst prepared by the present invention exhibits excellent water electrolysis hydrogen evolution performance and broad electrocatalytic application prospects. Specifically, by precisely constructing a Pt-W2N heterointerface and anchoring it on a highly conductive carbon nanoflower support, strong electronic synergistic effects between platinum and tungsten nitride are achieved, significantly enhancing the catalytic activity and stability.

[0030] Using tungsten nitride as a unique transition metal nitride matrix, its platinum-like d-band electron characteristics form a tight electronic coupling with platinum nanoparticles, synergistically optimizing the hydrogen adsorption free energy (ΔG H* ), so that excellent hydrogen evolution performance is exhibited in a wide pH range. During the nano reaction process, the high specific surface area and three-dimensional cross structure of the carbon nanoflower support not only effectively inhibit the aggregation of platinum and tungsten nitride nanoparticles, but also provide abundant active sites and efficient mass transfer channels, further enhancing the catalytic efficiency.

[0031] The Pt-W2N@C catalyst prepared by the method of the present invention achieves hydrogen evolution performance exceeding that of commercial platinum-carbon catalysts (20 wt.% Pt / C) at an extremely low platinum loading. For example, at 100 mA·cm -2At a current density of, its overpotential is significantly lower than that of traditional platinum-carbon catalysts, and at the same time, it exhibits excellent long-term stability (almost no attenuation after stable operation for 50 hours in 0.5 M H2SO4 and 1.0 M KOH). The catalyst shows high activity in a wide pH range, breaking through the bottleneck of limited performance of traditional platinum-based catalysts in non-acidic environments. The material prepared by the method of the present invention provides a new idea for the development of supported high-activity hydrogen evolution catalysts based on heterojunctions and has important industrial application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The advantages of the above and additional aspects of the present invention will become apparent and be readily understood from the following description of the embodiments in conjunction with the accompanying drawings, wherein:

[0033] Figure 1 is a SEM photograph obtained using Pt-W2N@C according to an embodiment of the present invention;

[0034] Figure 2 is a TEM photograph obtained using Pt-W2N@C according to an embodiment of the present invention and its grain size and element distribution map;

[0035] Figure 3 is a high-resolution transmission electron microscope (HRTEM) photograph obtained using Pt-W2N@C according to an embodiment of the present invention and its partial enlarged photograph;

[0036] Figure 4 is an XRD spectrum obtained using Pt-W2N@C according to an embodiment of the present invention and a JCPDS standard spectrum;

[0037] Figure 5 is a scanning electron microscope (SEM) photograph obtained using W-PDA according to a comparative example of the present invention;

[0038] Figure 6 is a transmission electron microscope (TEM) photograph and element distribution map obtained using Pt-(W-PDA) according to a comparative example of the present invention;

[0039] Figure 7 is a TEM photograph obtained using W2N@C according to a comparative example of the present invention;

[0040] Figure 8 is a comparative performance graph of hydrogen evolution by electrolysis of water obtained using working electrodes modified with different catalysts according to a test example of the present invention;

[0041] Figure 9 is a stability curve of hydrogen evolution by electrolysis of water obtained using a working electrode modified with Pt-W2N@C according to a test example of the present invention; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] The detailed description of the technical solution of the present invention aims to provide various exemplary embodiments. This description should be regarded as a supplementary explanation of the technical features of the present invention, rather than a limitation of its protection scope. It should be particularly noted that the terms used in this document are only for accurately describing specific embodiments and do not constitute any limitation to the present invention. For the expression of numerical ranges, it should be understood that all possible intermediate values and their sub-intervals within the range are clearly included. Specifically, any given numerical value or intermediate value within a numerical range, as well as the smaller intervals composed of these intermediate values, all fall within the protection scope of the present invention. The upper and lower limits of these sub-intervals can be independently included or excluded from the protection scope.

[0043] Unless otherwise clearly stated, all professional terms used in this specification have the technical meanings commonly understood by those skilled in the art. Although only the preferred implementation methods and materials are described in detail herein, in actual application or testing, any methods and materials equivalent to the technical solutions described in this document can be used alternatively.

[0044] Those skilled in the art can understand that without departing from the technical concept and protection scope of the present invention, various adjustments and improvements can be made to the specific implementation methods. Based on the technical solutions disclosed in this specification, other feasible implementation methods can be obviously deduced by relevant professionals. It should be emphasized that the embodiments provided in this specification are only for exemplary illustration and should not be understood as a limitation to the present invention.

[0045] It should be particularly noted that the expressions such as "comprising", "including", "having", "containing" used herein are all open descriptions, and their meanings are "including but not limited to".

[0046] It should be pointed out that the technical details not described in detail in this specification are all conventional technical means in the art and are not the core technical points of the present invention. In the specific implementation process, unless otherwise specified, the experimental environment is an ambient temperature of 20 to 30 °C.

[0047] All raw materials and reagents used in the embodiments of the present invention are commercially available standard products.

[0048] Examples

[0049] The preparation steps of the platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst with high activity and wide pH electrolytic water hydrogen production performance include:

[0050] Step 1: Synthesis of W-Polydopamine (PDA) precursor: Dissolve 540 mg of dopamine hydrochloride (DA-HCl) in 288 mL of absolute ethanol, and stir mechanically or sonicate until completely dissolved. Meanwhile, dissolve 1010 mg of sodium tungstate dihydrate (Na2WO4·2H2O) in 144 mL of deionized water, add 5 mL of ammonia water (NH4OH), and sonicate until completely dissolved. Subsequently, quickly mix the two solutions and magnetically stir at room temperature for 1 hour to allow the polymerization reaction to proceed. Centrifuge the resulting suspension, wash it twice with ethanol, and then dry it in a vacuum oven at 60 °C to obtain dark brown W-PDA powder.

[0051] Step 2: Synthesis of Pt-(W-PDA): Take 100 mg of the above W-PDA powder, disperse it evenly in 100 mL of absolute ethanol, and sonicate for 10 minutes to ensure uniform dispersion. Then, add 4 mL of a 2 μmol / mL ethanol solution of platinum acetylacetonate (C 10 H 14 O4Pt) to the suspension and sonicate for 10 minutes to promote polymerization. Finally, use a rotary evaporator to remove the solvent in a 50 °C water bath to obtain dark brown Pt-(W-PDA) powder.

[0052] Step 3: Synthesis of Pt-W2N@C catalyst: Place the synthesized Pt-(W-PDA) powder in a vacuum tube furnace, heat it to 800 °C at a heating rate of 5 °C / min under an Ar protective atmosphere, keep it at this temperature for 2 hours, and then naturally cool to room temperature to finally obtain the Pt-W2N@C catalyst.

[0053] Among them, Figure 1 : The SEM photograph obtained using Pt-W2N@C in the example shows that the conductive carbon nanoflower structure remains intact, and the results show that the size of the synthesized Pt-W2N@C is about 1 μm.

[0054] Among them, Figure 2 : The TEM photograph, grain size, and elemental distribution map obtained using Pt-W2N@C in the example show the uniform distribution of Pt-W2N heterojunction nanoparticles on the surface of the nanosheets, with an average particle size of about 3.13 nm and uniform distribution of each element.

[0055] Among them, Figure 3 : The high-resolution transmission electron microscope (HR-TEM) photograph and its partially enlarged picture obtained using Pt-W2N@C in the example clearly show the lattice fringes of various heterostructures, and an obvious Pt-W2N heterointerface can be observed, proving the successful synthesis of the Pt-W2N heterostructure at the nanoscale interface.

[0056] Among them, Figure 4: The XRD pattern obtained using Pt-W2N@C in the example and the JCPDS standard pattern. The prominent diffraction peaks of Pt and W2N in the test results indicate the successful synthesis of the Pt-W2N heterostructure embedded on the surface of the conductive carbon nanoflower flakes.

[0057] Comparative Example 1

[0058] Synthesis of W-poly(dopamine) (PDA) precursor: Dissolve 540 mg of dopamine hydrochloride (DA-HCl) in 288 mL of absolute ethanol and stir mechanically or sonicate until completely dissolved. Meanwhile, dissolve 1010 mg of sodium tungstate dihydrate (Na2WO4·2H2O) in 144 mL of deionized water, add 5 mL of ammonia water (NH4OH), and sonicate until completely dissolved. Subsequently, quickly mix the two solutions and stir magnetically at room temperature for 1 hour to allow the polymerization reaction to proceed. Centrifuge the resulting suspension, wash it twice with ethanol, and then dry it in a vacuum oven at 60 °C to obtain dark brown W-PDA powder.

[0059] Among them, Figure 5 : The scanning electron microscope (SEM) photograph obtained using W-PDA in Comparative Example 1 indicates the successful synthesis of the precursor of the conductive carbon nanoflower sphere structure formed by the cross-linking of multiple nanosheets.

[0060] Comparative Example 2

[0061] Synthesis of Pt-(W-PDA): Take 100 mg of the W-PDA powder described in Comparative Example 1 and disperse it uniformly in 100 mL of absolute ethanol, and sonicate for 10 minutes to ensure uniform dispersion. Then, add 4 mL of 2 μmol / mL platinum acetylacetonate (C 10 H 14 O4Pt) ethanol solution to the suspension and sonicate for 10 minutes to promote polymerization. Finally, use a rotary evaporator to remove the solvent in a 50 °C water bath to obtain dark brown Pt-(W-PDA) powder.

[0062] Among them, Figure 6 : The transmission electron microscope (TEM) photograph and elemental distribution map obtained using Pt-(W-PDA) in Comparative Example 2 indicate that the conductive carbon nanoflower structure remains intact after the introduction of Pt species, the Pt nanoparticles are uniformly dispersed on the surface of the nanosheets, and each element is evenly distributed, indicating the successful synthesis of Pt-(W-PDA).

[0063] Comparative Example 3

[0064] Synthesis of W2N@C: The W-PDA powder described in Comparative Example 1 was placed in a vacuum tube furnace and heated to 800 °C at a heating rate of 5 °C / min under an Ar protective atmosphere. After holding for 2 hours, it was naturally cooled to room temperature, and finally the W2N@C material was obtained.

[0065] Among them, Figure 7 : The TEM image obtained by using W2N@C in Comparative Example 3 shows the successful formation of the carbon nanoflower sphere structure, and the W2N nanoparticles are evenly distributed on the surface of the nanosheets.

[0066] Test Example

[0067] Weigh 5 mg of the catalyst powder, add isopropanol (900 μL) and Nafion membrane solution (100 μL), and ultrasonically treat for 10 minutes to form a uniform dispersion liquid, and then coat it on the electrode to be modified. The electrode to be modified can be carbon paper, glassy carbon electrode or membrane electrode, etc. Hereinafter, carbon paper will be further described.

[0068] Coat the above dispersion liquid on the surface of 1 cm 2 carbon paper, and the coating amount is 50 μL·cm -2 , and the mass loading is 0.25 mg·cm -2 . With the help of an infrared baking lamp, it is fully dried to make the catalyst particles evenly dispersed on the surface of the carbon paper.

[0069] Characterize and test the electrocatalytic hydrogen evolution performance of the above working electrode:

[0070] Use a Shanghai Chenhua electrochemical workstation (CHI760E). Test under a three-electrode system with 0.5 M H2SO4, 1.0 M KOH, and 1.0 M PBS solutions as electrolyte solutions. Electrochemical tests are all carried out with a reversible hydrogen electrode as the reference electrode, a graphite rod (in 0.5 M H2SO4 and 1.0 M PBS electrolytes) or a platinum sheet electrode (in 1.0 M KOH electrolyte) as the counter electrode, and the above-prepared electrode as the working electrode. To ensure the consistency of comparison, a commercial 20 wt.% Pt / C with the same amount and the same preparation procedure are used to prepare the 20 wt.% Pt / C working electrode.

[0071] Among them, Figure 8: Comparative performance graph of hydrogen evolution in electrolytic water obtained with working electrodes modified with different catalysts in the test examples. Different electrodes. The figure successively shows the linear sweep voltammograms of hydrogen evolution in electrolytic water in 0.5 M H2SO4, 1.0 M KOH, and 1.0 M PBS solution as electrolyte solutions. Pt-W2N@C is the carbon paper modified with the material of the example, and 20 wt.% Pt / C is the carbon paper modified with commercial 20 wt.% platinum-carbon. W2N@C is the carbon paper modified with the material of Comparative Example 3. As can be seen from the figure, the catalyst with a platinum / tungsten nitride heterojunction formed after high-temperature carbonization by introducing platinum has the best HER performance. At a current density corresponding to -2 100 mA·cm, the overpotential of the Pt-W2N@C catalyst is less than that of the commercial hydrogen evolution catalyst, indicating that this catalyst has high HER catalytic activity in a wide pH range.

[0072] Among them, Figure 9 : Stability curve of hydrogen evolution in electrolytic water obtained with the working electrode modified with Pt-W2N@C in the test example. The figure successively shows the chronoamperometry (i-t) curves of hydrogen evolution in electrolytic water in 0.5 M H2SO4 and 1.0 M KOH as electrolyte solutions. As can be seen from the figure, at a current density of -2 10 mA·cm, the Pt-W2N@C catalyst can stably operate for 50 h in both acidic and alkaline environments with basically no attenuation, demonstrating its excellent electrochemically stable hydrogen evolution performance.

[0073] The specific implementation manners of the present invention have been elaborated in detail above, aiming to provide a complete technical solution for those skilled in the art to implement and apply the present invention. For those skilled in the relevant art, various adjustments and improvements made to the embodiments based on the core principles of the present invention are within the obvious scope. It should be particularly noted that the technical principles disclosed by the present invention can be implemented through various embodiments without departing from its core idea and technical boundaries. Therefore, the protection scope of the present invention should not be limited to the specific embodiments listed in the specification, but should cover all implementation manners derived from the innovative principles and technical features of the present invention.

Claims

1. A platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst with high activity and wide pH performance for hydrogen production by electrolyzing water, characterized in that, The platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst has a carbon nanoflower-shaped conductive carrier and platinum / tungsten nitride heterojunction nanoparticles uniformly loaded on the conductive carrier.

2. A preparation method of a platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst with high activity and wide pH electrocatalytic hydrogen production performance as claimed in claim 1, characterized in that: A platinum-tungsten coordination precursor is designed and synthesized, and after high-temperature carbonization treatment, a Pt-W2N heterojunction electrocatalyst uniformly dispersed on a conductive carbon nanoflower matrix is obtained, and then the structure-activity relationship between the electronic structure and electrocatalytic hydrogen evolution performance of the catalyst is systematically studied; Among them, the platinum-tungsten coordination precursor is formed by the coordination reaction of a platinum source and a tungsten source mediated by dopamine, and the precise nano-scale construction of the Pt-W2N heterojunction can be realized by regulating the platinum / tungsten molar ratio and coordination environment; Through the compounding of the platinum-tungsten coordination precursor and the conductive carbon matrix, it uniformly crystallizes and grows on the surface of the conductive carbon-based nanoflower sheet layer, and a Pt-W2N heterojunction nanomaterial supported by a nitrogen-doped carbon matrix is formed during the high-temperature pyrolysis process, wherein the Pt nanoparticles and W2N form a synergistic catalytic active center through strong interfacial interaction. The specific preparation steps of the platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst with high activity and wide pH electrocatalytic hydrogen production performance are as follows: Step 1: Synthesis of the W-poly(dopamine) (PDA) precursor: Dissolve 540 mg of dopamine hydrochloride (DA-HCl) in 288 mL of absolute ethanol, and mechanically stir or ultrasonically treat until completely dissolved. At the same time, dissolve 1010 mg of sodium tungstate dihydrate (Na2WO4·2H2O) in 144 mL of deionized water, add 5 mL of ammonia water (NH4OH), and ultrasonically treat until completely dissolved. Subsequently, quickly mix the two solutions and magnetically stir at room temperature for 1 hour to carry out the polymerization reaction. Centrifuge the obtained suspension, wash it twice with ethanol, and then dry it in a 60 °C vacuum oven to obtain dark brown W-PDA powder. Step 2: Synthesis of Pt-(W-PDA): Take 100 mg of the above-mentioned W-PDA powder and disperse it evenly in 100 mL of absolute ethanol. Ultrasonically treat for 10 minutes to ensure uniform dispersion. Then, add 4 mL of a 2 μmol / mL ethanol solution of platinum acetylacetonate (C 10 H 14 O4Pt) to the suspension and ultrasonically treat for 10 minutes to promote polymerization. Finally, use a rotary evaporator to remove the solvent in a water bath at 50 °C to obtain dark brown Pt-(W-PDA) powder. Step 3: Synthesis of the Pt-W2N@C catalyst: Place the synthesized Pt-(W-PDA) powder in a vacuum tube furnace, heat it to 800 °C at a heating rate of 5 °C / min under an Ar protection atmosphere, keep it warm for 2 hours, and then naturally cool to room temperature to finally obtain the Pt-W2N@C catalyst.

3. The preparation method of the platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst with high activity and wide pH hydrogen production performance by electrolyzed water as claimed in claim 2, wherein: The W-PDA precursor is prepared by the polymerization reaction of sodium tungstate dihydrate and dopamine hydrochloride, and the polymerization time is 0.5 - 1.5 hours.

4. The preparation method of the platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst with high activity and wide pH hydrogen production performance by electrolyzed water as claimed in claim 2, wherein: The molar ratio of sodium tungstate dihydrate to dopamine hydrochloride is 1:5 - 1:8, and the ammonia water addition amount is 1 - 3% of the total volume of the mixed solution.

5. The preparation method of the platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst with high activity and wide pH electrolytic water hydrogen production performance as described in claim 2, characterized in that: The Pt-(W-PDA) material is prepared by introducing platinum acetylacetonate into the W-PDA precursor by the adsorption impregnation method. The concentration of the ethanol solution of platinum acetylacetonate is 1 - 3 μmol / mL, and the molar ratio of platinum to tungsten is 1:20 - 1:30, and the ultrasonic polymerization time is 10 - 15 minutes.

6. The preparation method of the platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst with high activity and wide pH hydrogen production performance by electrolyzed water as claimed in claim 2, wherein: The platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst is obtained by using the Pt-(W-PDA) material through step 3.

7. Application of the platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst with high activity and wide pH electrocatalytic water splitting hydrogen production performance described in claim 1 as an electrode modification material in the preparation of an electrocatalytic reaction electrode.

8. An electrode for hydrogen production by electrolyzing water, characterized in that, The active component of the electrode includes the platinum / tungsten nitride heterojunction carbon nanoflower electrocatalyst described in claim 1.

9. A method for producing hydrogen by electrolyzing water, characterized in that, The method uses the electrode described in claim 9 as the working electrode.

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