Intermetallic nanocatalyst for efficient hydrogen evolution and preparation method thereof

Abstract

The application discloses an intermetallic nanocatalyst for efficient hydrogen evolution and a preparation method thereof. The preparation method comprises the following steps: preparing a Ru@ZIF-8 precursor; introducing a proper proportion of cobalt salt, zinc salt and dimethyl imidazole by taking the Ru@ZIF-8 precursor as a crystal nucleus structure, and growing Co-ZIF-8 on the crystal nucleus structure in an epitaxial mode to form a Co-ZIF-8 / Ru@ZIF-8 precursor with a core-shell structure; and constructing an intermetallic nanocatalyst RuCo@NC in situ by using the Co-ZIF-8 / Ru@ZIF-8 precursor. In the RuCo@NC composite material prepared by the application, transition metal cobalt quantum dots are uniformly dispersed and active sites are fully exposed; the RuCo@NC composite material has a core-shell structure and a large specific surface area, so that the application of the RuCo@NC composite material in electrocatalysis can maintain high catalytic activity, excellent stability and excellent conductivity.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to an intermetallic nanocatalyst for efficient hydrogen evolution and its preparation method. Background Technology

[0002] Hydrogen energy, as a clean and sustainable new energy source, holds promise as a means to address excessive carbon dioxide emissions and the shortage of fossil fuels. Currently, countries worldwide are actively developing hydrogen energy, with Japan leading the way and making it a national policy. With increasing environmental pollution pressures, the demand for large-scale use of clean new energy sources is becoming more urgent. One important pathway for developing high-purity hydrogen is electrocatalytic water splitting to produce hydrogen; however, the efficiency of the hydrogen evolution reaction (HER) still needs improvement. Therefore, more stringent requirements are placed on the cost, catalytic activity, and catalytic stability of HER catalysts. Currently, carbon-supported platinum (Pt / C) catalysts are the most ideal and commercially available catalyst materials. However, the rarity and high cost of platinum significantly limit the widespread commercialization of hydrogen evolution from water electrolysis.

[0003] Over the past decade, non-precious metal catalysts have seen extensive and in-depth development due to their superior performance, and are considered the most promising alternatives to platinum-based catalysts. However, in harsh real-world environments, the catalytic performance of transition metal electrocatalysts still falls far short of requirements, and their stability remains the biggest bottleneck. Therefore, there is an urgent need to develop efficient, stable, inexpensive, and abundant electrocatalysts to replace precious metal catalysts. Electrolytic water-splitting catalysts capable of catalyzing the hydrogen evolution reaction can achieve a more efficient complete water splitting reaction, significantly reducing electrode preparation costs and hydrogen production costs, and simplifying production processes, thus possessing broader application prospects. However, designing and preparing highly active, stable, inexpensive, and readily available hydrogen evolution catalytic materials remains a challenging research problem in this field. Researchers have developed numerous non-precious metal hydrogen evolution catalytic materials to reduce system overpotential, lower energy consumption, and simultaneously improve electrode catalytic stability.

[0004] Intermetallic compounds are typical hydrogen evolution catalysts, but their strong adsorption of hydrogen limits their performance in hydrogen evolution. Traditional methods involve anion or cation doping of intermetallic compounds to optimize their hydrogen evolution performance; however, controlling the doping amount and dispersion remains challenging. Metal-organic frameworks (MOFs), due to their poor electrical conductivity, are not ideal for direct electrocatalytic hydrogen evolution and are therefore often used as precursors for the synthesis of various transition metal catalysts. However, high-temperature processes can easily damage the structure of MOFs and cause aggregation of active sites. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides an intermetallic nanocatalyst for efficient hydrogen evolution and its preparation method.

[0006] This invention provides a method for preparing an efficient intermetallic nanocatalyst for hydrogen evolution, comprising:

[0007] S1: Preparation of Ru@ZIF-8 precursor;

[0008] S2: Using the Ru@ZIF-8 precursor as the crystal nucleus structure, introduce appropriate proportions of cobalt salt, zinc salt and dimethylimidazole to epitaxially grow Co-ZIF-8 on the crystal nucleus structure to form a core-shell structured Co-ZIF-8 / Ru@ZIF-8 precursor.

[0009] S3: In-situ construction of intermetallic nanocatalyst RuCo@NC using the Co-ZIF-8 / Ru@ZIF-8 precursor.

[0010] In one embodiment of the present invention, S1 includes:

[0011] S1.1: Utilizing the coordination of Zn ions with dimethylimidazole, a ZIF-8 precursor with a dodecahedral structure of transition metal is formed;

[0012] S1.2: Utilizing the porous structure of the precursor ZIF-8 to adsorb Ru 3+ To prepare Ru@ZIF-8 precursor.

[0013] In one embodiment of the present invention, S1.1 includes:

[0014] Weigh out an appropriate amount of Zn(NO3)2·6H2O and dissolve it in a methanol solution to form solution A;

[0015] Weigh out an appropriate amount of dimethylimidazole and dissolve it in methanol solution to form solution B;

[0016] Add solution A dropwise to solution B and stir thoroughly at room temperature to obtain the first suspension.

[0017] The first suspension was centrifuged and washed multiple times with methanol. The washed first product was then placed in a drying oven for constant temperature drying to obtain the ZIF-8 precursor.

[0018] In one embodiment of the present invention, the mass ratio of Zn(NO3)2·6H2O to dimethylimidazole is (1:2) to (1:3).

[0019] In one embodiment of the present invention, S1.2 includes:

[0020] Weigh out an appropriate amount of RuCl₃·xH₂O and dissolve it in a deionized aqueous solution to form solution C;

[0021] Weigh an appropriate amount of the ZIF-8 precursor, dissolve it in a deionized aqueous solution, and ultrasonically disperse it evenly to form solution D;

[0022] Add the C solution dropwise to the D solution and stir thoroughly at room temperature to obtain a second suspension.

[0023] The resulting second suspension was centrifuged and washed multiple times with a mixture of ethanol and deionized water. The washed second product was then placed in a drying oven and dried at a constant temperature to obtain the Ru@ZIF-8 precursor.

[0024] In one embodiment of the present invention, the mass ratio of RuCl₃·xH₂O to the ZIF-8 precursor is (1:50) to (1:25).

[0025] In one embodiment of the present invention, S2 includes:

[0026] Weigh an appropriate amount of the Ru@ZIF-8 precursor and dissolve it in a methanol solution to form solution E;

[0027] Weigh out appropriate amounts of Zn(NO3)2·6H2O and Co(NO3)2·6H2O and dissolve them in methanol solution to form solution F;

[0028] The F solution was added dropwise to the E solution and stirred thoroughly at room temperature. Then, an appropriate amount of dimethylimidazole methanol solution was added dropwise and stirred thoroughly at room temperature to obtain a third suspension.

[0029] The resulting third suspension was centrifuged and washed multiple times with ethanol. Finally, the washed third product was placed in a drying oven and dried at a constant temperature to obtain the Co-ZIF-8 / Ru@ZIF-8 precursor.

[0030] In one embodiment of the present invention, the mass ratio of Zn(NO3)2·6H2O, Co(NO3)2·6H2O and dimethylimidazole is (4:1:1.4) to (2:1:0.8).

[0031] In one embodiment of the present invention, S3 includes:

[0032] The freeze-dried Co-ZIF-8 / Ru@ZIF-8 precursor was placed in a horizontal tube furnace and heated to 900-1000℃ at a rate of 5-10℃ / min under an inert atmosphere and held for 3-6 hours to obtain the RuCo@NC composite material.

[0033] Another aspect of the present invention provides an intermetallic nanocatalyst for efficient hydrogen evolution, prepared using the preparation method described in any one of the above embodiments.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] 1. This invention provides a RuCo@NC intermetallic nanocatalyst for efficient hydrogen evolution and its preparation method. The RuCo@NC is a composite material in which cobalt quantum dots of transition metal are uniformly dispersed, fully exposing active sites. The RuCo@NC composite material has a core-shell structure and a large specific surface area, enabling it to maintain high catalytic activity, excellent stability, and superior conductivity in electrocatalysis applications. The raw materials involved in the preparation only involve commonly used reagents such as zinc nitrate hexahydrate, cobalt nitrate hexahydrate, dimethylimidazole, methanol, and ethanol, as well as trace amounts of precious metals. The cost is low, the product purity is high, the preparation process is simple, and it is easy to industrialize. Furthermore, the preparation process of this invention can be extended to the preparation of other transition metal composite electrocatalysts.

[0036] 2. This invention uses the metal-organic framework (MOF) precursor Ru@ZIF-8 and introduces a very small amount of noble metal Ru. By controlling the spatial distance between metal sites through parameters such as reaction time, reaction temperature, and raw material ratio, the aggregation of metal atoms at high temperature is effectively avoided during the thermal decomposition process, thus preparing an ultrafine intermetallic nanocomposite catalyst supported on porous carbon.

[0037] 3. The preparation method of this invention can prepare composite materials with unique three-dimensional core-shell structure and high specific surface area, effectively suppressing the aggregation of metal nanoparticles and fully exposing active sites; in-situ pyrolysis at high temperature yields porous carbon-coated intermetallic nanoparticles, improving the conductivity of the composite material and facilitating the acceleration of proton and ion transport during the reaction; innovatively, a very small amount of noble metal Ru is doped into the transition metal matrix composite material, which greatly improves the reactivity and lowers the reaction energy barrier, enabling the composite material to exhibit excellent electrocatalytic properties when used as a catalyst for the hydrogen evolution reaction.

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a method for preparing an efficient intermetallic nanocatalyst for hydrogen evolution provided in an embodiment of the present invention;

[0040] Figure 2 This is a scanning electron microscope (SEM) image of the RuCo@NC composite material prepared in Example 2 of the present invention;

[0041] Figure 3 This is a transmission electron microscope (TEM) image of the RuCo@NC composite material prepared in Example 2 of the present invention;

[0042] Figure 4 This is the X-ray diffraction energy spectrum (XRD) analysis pattern of the RuCo@NC composite material prepared in Example 2 of the present invention;

[0043] Figure 5 The image shows the HER linear scan voltammetry curve of the RuCo@NC composite material prepared in Example 2 of this invention, with a scan rate of 5 mV / s in a 1.0 mol / L potassium hydroxide electrolyte. Detailed Implementation

[0044] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following, in conjunction with the accompanying drawings and specific embodiments, provides a detailed description of an intermetallic nanocatalyst for efficient hydrogen evolution and its preparation method based on the present invention.

[0045] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a more in-depth and concrete understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the technical solutions of the present invention.

[0046] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that an article or apparatus comprising a list of elements includes not only those elements but also other elements not expressly listed. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or apparatus that includes said element.

[0047] Example 1

[0048] Please see Figure 1 , Figure 1 This is a schematic flowchart of a method for preparing an efficient intermetallic nanocatalyst for hydrogen evolution according to an embodiment of the present invention. The preparation method specifically includes the following steps:

[0049] S1: Preparation of Ru@ZIF-8 precursor.

[0050] Step S1 in this embodiment includes:

[0051] S1.1: Utilizing the coordination of Zn ions with dimethylimidazole, a ZIF-8 precursor with a dodecahedral structure of transition metal is formed.

[0052] A suitable amount of Zn(NO3)2·6H2O was weighed and dissolved in methanol to form solution A; a suitable amount of dimethylimidazole was weighed and dissolved in methanol to form solution B; solution A was added dropwise to solution B, and the mixture was stirred thoroughly at room temperature to obtain a first suspension; the first suspension was centrifuged and washed several times with methanol, and then the washed first product was placed in a drying oven for constant temperature drying to obtain the ZIF-8 precursor. The mass ratio of Zn(NO3)2·6H2O to dimethylimidazole was (1:2) to (1:3), preferably 1:2.4.

[0053] Specifically, 800–1000 mg of Zn(NO3)2·6H2O was weighed and dissolved in 25 mL of methanol solution, denoted as solution A; 2–3 g of dimethylimidazole was weighed and dissolved in 25 mL of methanol solution, denoted as solution B; solution A was slowly added dropwise to solution B, and the mixture was stirred at room temperature for 4–8 hours to obtain a suspension. The resulting suspension was centrifuged and washed 3–4 times with methanol. Finally, the product was placed in a drying oven at 60–100 °C and dried for 8 hours to obtain the ZIF-8 precursor.

[0054] S1.2: Utilizing the porous structure of the precursor ZIF-8 to adsorb Ru 3+ To prepare Ru@ZIF-8 precursor.

[0055] A suitable amount of RuCl₃·xH₂O was weighed and dissolved in a deionized aqueous solution to form solution C; a suitable amount of the ZIF-8 precursor was weighed and dissolved in a deionized aqueous solution and ultrasonically dispersed to form solution D; solution C was added dropwise to solution D, and the mixture was stirred thoroughly at room temperature to obtain a second suspension; the obtained second suspension was centrifuged and washed multiple times with a mixed solution of ethanol and deionized water, and then the washed second product was placed in a drying oven and dried at a constant temperature to obtain the Ru@ZIF-8 precursor. The mass ratio of RuCl₃·xH₂O to the ZIF-8 precursor was (1:50) to (1:25).

[0056] Specifically, 1–4 mg of RuCl₃·xH₂O (ruthenium trichloride hydrate) was weighed and dissolved in 5 mL of deionized water, denoted as solution C. 80–110 mg of ZIF-8 was weighed and dissolved in 5 mL of deionized water and ultrasonically dispersed, denoted as solution D. Solution C was slowly added dropwise to solution D, and the mixture was stirred at room temperature for 40–50 min to obtain a second suspension. The second suspension was centrifuged and washed 3–4 times with a mixture of ethanol and deionized water. Finally, the washed second product was placed in a drying oven at 60–100 °C and dried for 6–10 h to obtain the precursor Ru@ZIF-8.

[0057] It should be noted that the morphology, phase composition, and dodecahedral size of Ru@ZIF-8 can be controlled by adjusting the amount of RuCl3·xH2O and ZIF-8 precursor and adding surfactants.

[0058] S2: Using the Ru@ZIF-8 precursor as the crystal nucleus structure, introduce appropriate proportions of cobalt salt, zinc salt and dimethylimidazole to epitaxially grow Co-ZIF-8 on the crystal nucleus structure to form a core-shell structured Co-ZIF-8 / Ru@ZIF-8 precursor.

[0059] A suitable amount of the Ru@ZIF-8 precursor was weighed and dissolved in methanol solution to form solution E; suitable amounts of Zn(NO3)2·6H2O and Co(NO3)2·6H2O were weighed and dissolved in methanol solution to form solution F; solution F was added dropwise to solution E, and stirred thoroughly at room temperature, followed by the addition of a suitable amount of dimethylimidazole methanol solution, and stirred thoroughly at room temperature to obtain a third suspension; the obtained third suspension was centrifuged and washed several times with ethanol, and finally the washed third product was placed in a drying oven and dried at a constant temperature to obtain the Co-ZIF-8 / Ru@ZIF-8 precursor. The mass ratio of Zn(NO3)2·6H2O, Co(NO3)2·6H2O and dimethylimidazole was (4:1:1.4) to (2:1:0.8).

[0060] Specifically, 30–60 mg of Ru@ZIF-8 was weighed and dissolved in 10 mL of methanol solution, denoted as solution E. 230–300 mg of Zn(NO3)2·6H2O and 30–60 mg of Co(NO3)2·6H2O were weighed and dissolved in 10 mL of methanol solution, denoted as solution F. Solution F was slowly added dropwise to solution E, and the mixture was stirred at room temperature for 20–40 min. 70–100 mg of dimethylimidazole was dissolved in 10 mL of methanol solution and stirred at room temperature for 20–30 h, then slowly added dropwise to the mixture of solutions F and E. The resulting third suspension was centrifuged and washed 3–4 times with ethanol. Finally, the washed third product was placed in a drying oven at 60–100 °C and dried for 6–10 h to obtain the Co-ZIF-8 / Ru@ZIF-8 precursor.

[0061] It should be noted that by adjusting the ratio of zinc salt (Zn(NO3)2·6H2O) and cobalt salt (Co(NO3)2·6H2O), as well as the concentration of reactants such as dimethylimidazole and the addition of surfactants, the morphology, phase composition, core-shell thickness, etc. of the Co-ZIF-8 / Ru@ZIF-8 precursor can be controlled.

[0062] S3: In-situ construction of intermetallic nanocatalyst RuCo@NC using the Co-ZIF-8 / Ru@ZIF-8 precursor.

[0063] The freeze-dried Co-ZIF-8 / Ru@ZIF-8 precursor was placed in a horizontal tube furnace and heated to 900-1000°C at a rate of 5-10°C / min under an inert or reducing atmosphere. This temperature was maintained for 3-6 hours to obtain the RuCo@NC composite material. In this embodiment, the reducing atmosphere was a hydrogen-argon mixture. Cobalt and ruthenium in the Co-ZIF-8 / Ru@ZIF-8 precursor undergo an alloying reaction under a reducing atmosphere and at a certain temperature. During this process, the Co-ZIF-8 / Ru@ZIF-8 precursor retains its carbon skeleton, while metallic ruthenium and cobalt undergo an alloying reaction under high-temperature reducing conditions to form a ruthenium-cobalt nano-alloy. By changing experimental conditions and process parameters such as carrier gas atmosphere, gas flow rate, reaction temperature, and time, a carbon-coated intermetallic nanocomposite catalyst was constructed in situ. This study investigated the effects of different calcination atmospheres, gas flow rates, calcination temperatures, calcination times, precursor morphology, and compositions on the morphology, intermetallic composition, pore size distribution, N doping concentration, and crystal defects of RuCo@NC. In-situ pyrolysis at high temperatures yielded porous carbon-coated intermetallic nanoparticles, improving the conductivity of the composite material and facilitating the acceleration of proton and ion transport during the reaction process.

[0064] The RuCo@NC composite material prepared in this invention possesses a unique core-shell structure, a large specific surface area, and uniformly dispersed ruthenium-based quantum dots, which fully exposes the active sites of the catalyst. Furthermore, the RuCo@NC composite material is rich in nitrogen doping, which enables better synergistic effects. Therefore, when used as a functional electrocatalyst for the hydrogen evolution reaction (HER), the RuCo@NC composite material exhibits excellent electrocatalytic properties (HER overpotential in 1.0 mol / L KOH solution: η = 10 mA cm⁻¹). -2 =133mV), the RuCo@NC composite material prepared by this invention not only has strong conductivity, many active sites, and good electrocatalytic performance, but also uses low-cost raw materials, has a simple process, and low reaction energy consumption, which can realize large-scale preparation. It is a new method for preparing a highly efficient and economical water electrolysis catalyst.

[0065] When the RuCo@NC composite material prepared in this invention is used as a catalyst for water electrolysis, the specific steps are as follows: the prepared RuCo@NC composite material is loaded onto a glassy carbon electrode as the working electrode, a saturated calomel electrode is used as the reference electrode, and a carbon rod is used as the counter electrode. Its HER electrochemical performance is tested in a 1.0 mol / L KOH solution at room temperature and pressure.

[0066] This invention provides a RuCo@NC intermetallic nanocatalyst for efficient hydrogen evolution and its preparation method. The RuCo@NC is a composite material in which cobalt quantum dots are uniformly dispersed, fully exposing active sites. The RuCo@NC composite material possesses a core-shell structure and a large specific surface area, enabling it to maintain high catalytic activity, excellent stability, and superior conductivity in electrocatalysis applications. The raw materials used in its preparation only involve commonly used reagents such as zinc nitrate hexahydrate, cobalt nitrate hexahydrate, dimethylimidazole, methanol, and ethanol, as well as trace amounts of precious metals. This results in low cost, high product purity, a simple preparation process, and ease of industrial production. Furthermore, the preparation process of this invention can be extended to the preparation of other transition metal composite electrocatalysts.

[0067] Example 2

[0068] Based on Example 1, this example provides a core-shell metal-organic framework (MOF) derived intermetallic nanocatalyst for efficient hydrogen evolution and its preparation method, with the chemical formula RuCo@NC. The preparation method specifically includes the following steps:

[0069] Step 1: Preparation of Ru@ZIF-8, a MOF material anchored to noble metal ions.

[0070] The coordination of Zn ions with dimethylimidazole was utilized to form a transition metal dodecahedral structure (ZIF-8). Specifically, 961.4 mg of Zn(NO3)2·6H2O was dissolved in 25 mL of methanol solution (referred to as solution A), and 2.357 g of dimethylimidazole was dissolved in 25 mL of methanol solution (referred to as solution B). Solution A was slowly added dropwise to solution B, and the mixture was stirred at room temperature for 6 hours. The resulting first suspension was centrifuged and washed 3-4 times with methanol. Finally, the washed first product was placed in a drying oven at 80 °C and dried for 8 hours to obtain the ZIF-8 precursor.

[0071] Subsequently, Ru@ZIF-8 was prepared by adsorbing Ru3+ using the porous structure of the ZIF-8 precursor. Specifically, 2 mg of RuCl3·xH2O was dissolved in 5 mL of deionized water and labeled as solution C. 100 mg of the ZIF-8 precursor was dissolved in 5 mL of deionized water and ultrasonically dispersed and labeled as solution D. Solution C was slowly added dropwise to solution D, and the mixture was stirred at room temperature for 30 min to obtain a second suspension. The second suspension was centrifuged and washed 3-4 times with a mixture of ethanol and deionized water. Finally, the washed second product was placed in an 80℃ drying oven and dried for 8 h to obtain the Ru@ZIF-8 precursor.

[0072] Step 2: Construct the core-shell metal-based MOF precursor Co-ZIF-8 / Ru@ZIF-8 in situ using the Ru@ZIF-8 precursor.

[0073] Using Ru@ZIF-8 as the nucleus structure, Co-ZIF-8 was epitaxially grown on the nucleus by introducing appropriate proportions of cobalt salt, zinc salt, and dimethylimidazole, forming a core-shell structured metal-based MOF precursor, Co-ZIF-8 / Ru@ZIF-8. Specifically, 50 mg of the Ru@ZIF-8 precursor was dissolved in 10 mL of methanol solution (referred to as solution E), and 236.8 mg of Zn(NO3)2·6H2O and 59.2 mg of Co(NO3)2·6H2O were dissolved in 10 mL of methanol solution (referred to as solution F). Solution F was slowly added dropwise to solution E, and the mixture was stirred at room temperature for 30 min. Subsequently, 82 mg of dimethylimidazole was dissolved in 10 mL of methanol solution, stirred at room temperature for 24 h, and then slowly added dropwise to the mixture of solutions F and E. The resulting third suspension was centrifuged and washed 3-4 times with ethanol. Finally, the washed third product was placed in a drying oven at 80℃ and dried at a constant temperature for 8 hours to obtain the Co-ZIF-8 / Ru@ZIF-8 precursor.

[0074] Step 3: Construct the intermetallic nanocatalyst RuCo@NC in situ using the Co-ZIF-8 / Ru@ZIF-8 precursor.

[0075] The freeze-dried precursor was placed in a horizontal tube furnace and heated to 950°C at a rate of 5°C / min under an inert or reducing atmosphere. The mixture was then held at this temperature for 6 hours to obtain the RuCo@NC composite material.

[0076] Please see Figure 2 , Figure 2 This is a scanning electron microscope (SEM) image of the RuCo@NC composite material prepared in Example 2 of this invention. Figure 2 It can be seen that the RuCo@NC composite material after pyrolysis can still basically maintain the dodecahedral structure, indicating that it has well preserved the framework structure of the precursor.

[0077] Please see Figure 3 , Figure 3 This is a transmission electron microscope (TEM) image of the RuCo@NC composite material prepared in Example 2 of this invention. From... Figure 3 It can be seen that the RuCo@NC sample still maintains a porous dodecahedral core-shell structure. It can also be observed that the RuCo nano-metal particles covering the middle layer of the core-shell structure do not agglomerate and are uniformly distributed in the middle layer of the core-shell material.

[0078] Please see Figure 4 , Figure 4 This is the X-ray diffraction energy dispersive spectroscopy (XRD) pattern of the RuCo@NC composite material prepared in Example 2 of this invention. From... Figure 4 As can be seen, the characteristic peaks of Co were observed at 44.45° and 69.9° in the XRD diffraction peaks of the RuCo@NC sample. Since the characteristic peak of Ru is located at 44.0° and has a high intensity, it overlaps with the characteristic peak of Co, making it difficult to directly observe the peak of Ru in the XRD image.

[0079] Please see Figure 5 , Figure 5 The RuCo@NC composite material prepared in Example 2 of this invention is shown in the HER linear scan voltammetry curve in a 1.0 mol / L potassium hydroxide electrolyte at a scan rate of 5 mV / s. The current density is 10 mA / cm². -2 At that time, the overpotential of RuCo@NC was 154mV. In practical applications, the ultimate goal of electrocatalytic water splitting for hydrogen production is to reduce costs and increase efficiency. This embodiment uses an ultra-low amount of the noble metal Ru to assist in enhancing the intrinsic activity of the low-cost transition metal Co, effectively improving the catalytic performance of RuCo@NC electrocatalysis while significantly reducing costs.

[0080] Example 3

[0081] Based on the above embodiments, this embodiment provides another method for preparing and applying RuCo@NC (denoted as RuCo@NC-1), an intermetallic nanocatalyst for efficient hydrogen evolution. The specific preparation method is as follows:

[0082] Step 1: Preparation of Ru@ZIF-8, a MOF material anchored to noble metal ions.

[0083] The coordination of Zn ions with dimethylimidazole was utilized to form a transition metal dodecahedral structure (ZIF-8): 961.4 mg of Zn(NO3)2·6H2O was dissolved in 25 mL of methanol solution (solution A), and 2.357 g of dimethylimidazole was dissolved in 25 mL of methanol solution (solution B). Solution A was slowly added dropwise to solution B, and the mixture was stirred at room temperature for 6 hours. The resulting first suspension was centrifuged and washed 3-4 times with methanol. Finally, the washed first product was placed in an 80℃ drying oven and dried for 8 hours to obtain the ZIF-8 precursor.

[0084] Subsequently, Ru@ZIF-8 was prepared by adsorbing Ru3+ using the porous structure of the ZIF-8 precursor. Specifically, 2 mg of RuCl3·xH2O was dissolved in 5 mL of deionized water and labeled as solution C. 100 mg of the ZIF-8 precursor was dissolved in 5 mL of deionized water and ultrasonically dispersed and labeled as solution D. Solution C was slowly added dropwise to solution D, and the mixture was stirred at room temperature for 30 min to obtain a second suspension. The second suspension was centrifuged and washed 3-4 times with a mixture of ethanol and deionized water. Finally, the washed second product was placed in an 80℃ drying oven and dried for 8 h to obtain the Ru@ZIF-8 precursor.

[0085] Step 2: Construct the core-shell metal-based MOF precursor Co-ZIF-8 / Ru@ZIF-8 in situ using the Ru@ZIF-8 precursor.

[0086] Using Ru@ZIF-8 as the nucleus structure, Co-ZIF-8 was epitaxially grown on the nucleus by introducing appropriate proportions of cobalt salt, zinc salt, and dimethylimidazole, forming a core-shell structured metal-based MOF precursor, Co-ZIF-8 / Ru@ZIF-8. Specifically, 50 mg of the Ru@ZIF-8 precursor was dissolved in 10 mL of methanol solution (referred to as solution E), and 197.3 mg of Zn(NO3)2·6H2O and 98.67 mg of Co(NO3)2·6H2O were dissolved in 10 mL of methanol solution (referred to as solution F). Solution F was slowly added dropwise to solution E, and the mixture was stirred at room temperature for 30 min. Subsequently, 82 mg of dimethylimidazole was dissolved in 10 mL of methanol solution, stirred at room temperature for 24 h, and then slowly added dropwise to the mixture of solutions F and E. The resulting third suspension was centrifuged and washed 3-4 times with ethanol. Finally, the washed third product was placed in a drying oven at 80℃ and dried at a constant temperature for 8 hours to obtain the Co-ZIF-8 / Ru@ZIF-8 precursor.

[0087] Step 3: Construct the intermetallic nanocatalyst RuCo@NC in situ using the Co-ZIF-8 / Ru@ZIF-8 precursor.

[0088] The freeze-dried precursor was placed in a horizontal tube furnace and heated to 950°C at a rate of 5°C / min under an inert or reducing atmosphere. The mixture was then held at this temperature for 6 hours to obtain the RuCo@NC composite material.

[0089] Example 4

[0090] Based on the above embodiments, this embodiment provides another method for preparing and applying RuCo@NC (denoted as RuCo@NC-2), an intermetallic nanocatalyst for efficient hydrogen evolution. The specific preparation method is as follows:

[0091] Step 1: Preparation of Ru@ZIF-8, a MOF material anchored to noble metal ions.

[0092] The coordination of Zn ions with dimethylimidazole was utilized to form a transition metal dodecahedral structure (ZIF-8). Specifically, 961.4 mg of Zn(NO3)2·6H2O was dissolved in 25 mL of methanol solution (referred to as solution A), and 2.357 g of dimethylimidazole was dissolved in 25 mL of methanol solution (referred to as solution B). Solution A was slowly added dropwise to solution B, and the mixture was stirred at room temperature for 6 hours. The resulting first suspension was centrifuged and washed 3-4 times with methanol. Finally, the washed first product was placed in a drying oven at 80 °C and dried for 8 hours to obtain the ZIF-8 precursor.

[0093] Subsequently, Ru@ZIF-8 was prepared by adsorbing Ru3+ using the porous structure of the ZIF-8 precursor. 4 mg of RuCl3·xH2O was dissolved in 5 mL of deionized water (solution C), and 100 mg of the ZIF-8 precursor was dissolved in 5 mL of deionized water (solution D). The solution was then ultrasonically dispersed and labeled as solution D. Solution C was slowly added dropwise to solution D, and the mixture was stirred at room temperature for 30 min to obtain a second suspension. The second suspension was centrifuged and washed 3-4 times with a mixture of ethanol and deionized water. Finally, the washed second product was placed in an 80℃ drying oven and dried for 8 h to obtain the Ru@ZIF-8 precursor.

[0094] Step 2: Construct the core-shell metal-based MOF precursor Co-ZIF-8 / Ru@ZIF-8 in situ using the Ru@ZIF-8 precursor.

[0095] Using Ru@ZIF-8 as the nucleus structure, Co-ZIF-8 was epitaxially grown on the nucleus by introducing appropriate proportions of cobalt salt, zinc salt, and dimethylimidazole, forming a core-shell structured metal-based MOF precursor, Co-ZIF-8 / Ru@ZIF-8. Specifically, 50 mg of the Ru@ZIF-8 precursor was dissolved in 10 mL of methanol solution (referred to as solution E), and 236.8 mg of Zn(NO3)2·6H2O and 59.2 mg of Co(NO3)2·6H2O were dissolved in 10 mL of methanol solution (referred to as solution F). Solution F was slowly added dropwise to solution E, and the mixture was stirred at room temperature for 30 min. Subsequently, 82 mg of dimethylimidazole was dissolved in 10 mL of methanol solution, stirred at room temperature for 24 h, and then slowly added dropwise to the mixture of solutions F and E. The resulting third suspension was centrifuged and washed 3-4 times with ethanol. Finally, the washed third product was placed in a drying oven at 80℃ and dried at a constant temperature for 8 hours to obtain the Co-ZIF-8 / Ru@ZIF-8 precursor.

[0096] Step 3: Construct the intermetallic nanocatalyst RuCo@NC in situ using the Co-ZIF-8 / Ru@ZIF-8 precursor.

[0097] The freeze-dried precursor was placed in a horizontal tube furnace and heated to 950°C at a rate of 5°C / min under an inert or reducing atmosphere. The mixture was then held at this temperature for 6 hours to obtain the RuCo@NC composite material.

[0098] Example 5

[0099] Based on the above embodiments, this embodiment provides another method for preparing and applying RuCo@NC (denoted as RuCo@NC-3), an intermetallic nanocatalyst for efficient hydrogen evolution. The specific preparation method is as follows:

[0100] Step 1: Preparation of Ru@ZIF-8, a MOF material anchored to noble metal ions.

[0101] The coordination of Zn ions with dimethylimidazole was utilized to form a transition metal dodecahedral structure (ZIF-8): 961.4 mg of Zn(NO3)2·6H2O was dissolved in 25 mL of methanol solution (solution A), and 2.357 g of dimethylimidazole was dissolved in 25 mL of methanol solution (solution B). Solution A was slowly added dropwise to solution B, and the mixture was stirred at room temperature for 6 hours. The resulting first suspension was centrifuged and washed 3-4 times with methanol. Finally, the washed first product was placed in an 80℃ drying oven and dried for 8 hours to obtain the ZIF-8 precursor.

[0102] Subsequently, Ru@ZIF-8 was prepared by adsorbing Ru3+ using the porous structure of the ZIF-8 precursor. 4 mg of RuCl3·xH2O was dissolved in 5 mL of deionized water and labeled as solution C. 100 mg of the ZIF-8 precursor was dissolved in 5 mL of deionized water and ultrasonically dispersed and labeled as solution D. Solution C was slowly added dropwise to solution D, and the mixture was stirred at room temperature for 30 min to obtain a second suspension. The second suspension was centrifuged and washed 3-4 times with a mixture of ethanol and deionized water. Finally, the washed second product was placed in an 80℃ drying oven and dried for 8 h to obtain the Ru@ZIF-8 precursor.

[0103] Step 2: Construct the core-shell metal-based MOF precursor Co-ZIF-8 / Ru@ZIF-8 in situ using the Ru@ZIF-8 precursor.

[0104] Using Ru@ZIF-8 as the nucleus structure, Co-ZIF-8 was epitaxially grown on the nucleus by introducing appropriate proportions of cobalt salt, zinc salt, and dimethylimidazole, forming a core-shell structured metal-based MOF precursor, Co-ZIF-8 / Ru@ZIF-8. Specifically, 50 mg of the Ru@ZIF-8 precursor was dissolved in 10 mL of methanol solution (referred to as solution E), and 197.3 mg of Zn(NO3)2·6H2O and 98.67 mg of Co(NO3)2·6H2O were dissolved in 10 mL of methanol solution (referred to as solution F). Solution F was slowly added dropwise to solution E, and the mixture was stirred at room temperature for 30 min. Subsequently, 82 mg of dimethylimidazole was dissolved in 10 mL of methanol solution, stirred at room temperature for 24 h, and then slowly added dropwise to the mixture of solutions F and E. The resulting third suspension was centrifuged and washed 3-4 times with ethanol. Finally, the washed third product was placed in a drying oven at 80℃ and dried at a constant temperature for 8 hours to obtain the Co-ZIF-8 / Ru@ZIF-8 precursor.

[0105] Step 3: Construct the intermetallic nanocatalyst RuCo@NC in situ using the Co-ZIF-8 / Ru@ZIF-8 precursor.

[0106] The freeze-dried precursor was placed in a horizontal tube furnace and heated to 950°C at a rate of 5°C / min under an inert or reducing atmosphere. The mixture was then held at this temperature for 6 hours to obtain the RuCo@NC composite material.

[0107] Another aspect of the present invention provides an intermetallic nanocatalyst for efficient hydrogen evolution, prepared using the preparation method described in any one of the above embodiments.

[0108] In summary, this invention utilizes the metal-organic framework (MOF) precursor Ru@ZIF-8, introduces a trace amount of the noble metal Ru, and controls the spatial distance between metal sites by adjusting parameters such as reaction time, reaction temperature, and raw material ratio. This effectively prevents the aggregation of metal atoms at high temperatures during thermal decomposition, thus preparing an ultrafine intermetallic nanocomposite catalyst supported on porous carbon. The preparation method of this invention can produce a composite material with a unique three-dimensional core-shell structure and high specific surface area, effectively inhibiting the aggregation of metal nanoparticles and fully exposing the active sites. In-situ decomposition at high temperatures yields porous carbon-coated intermetallic nanoparticles, improving the conductivity of the composite material and facilitating the transport of protons and ions during the reaction. The innovative approach of doping a trace amount of the noble metal Ru into a transition metal-based composite material significantly enhances the reactivity and lowers the reaction energy barrier, enabling the composite material to exhibit excellent electrocatalytic properties when used as a catalyst for the hydrogen evolution reaction.

[0109] In the several embodiments provided by this invention, it should be understood that the apparatus and methods disclosed in this invention can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For example, the division of modules is merely a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed.

[0110] Furthermore, the functional modules in the various embodiments of the present invention can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The integrated module can be implemented in hardware or in the form of hardware plus software functional modules.

[0111] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an intermetallic nanocatalyst for efficient hydrogen evolution, characterized in that, include: S1: Preparation of Ru@ZIF-8 precursor; S2: Using the Ru@ZIF-8 precursor as the crystal nucleus structure, introduce appropriate proportions of cobalt salt, zinc salt and dimethylimidazole to epitaxially grow Co-ZIF-8 on the crystal nucleus structure to form a core-shell structured Co-ZIF-8 / Ru@ZIF-8 precursor. S3: Constructing intermetallic nanocatalyst RuCo@NC in situ using the Co-ZIF-8 / Ru@ZIF-8 precursor; S1 includes: S1.1: Utilizing the coordination of Zn ions with dimethylimidazole, a ZIF-8 precursor with a dodecahedral structure of transition metal is formed; S1.2: Utilizing the porous structure of the precursor ZIF-8 to adsorb Ru 3+ Preparation of Ru@ZIF-8 precursor; S1.2 includes: Weigh out an appropriate amount of RuClз xH2O dissolves in a deionized aqueous solution to form solution C; Weigh an appropriate amount of the ZIF-8 precursor, dissolve it in a deionized aqueous solution, and ultrasonically disperse it evenly to form solution D; Add the C solution dropwise to the D solution and stir thoroughly at room temperature to obtain a second suspension. The resulting second suspension was centrifuged and washed multiple times with a mixture of ethanol and deionized water. The washed second product was then placed in a drying oven and dried at a constant temperature to obtain the Ru@ZIF-8 precursor. The RuClз The mass ratio of xH2O to the ZIF-8 precursor is (1:50) to (1:25); S2 includes: Weigh an appropriate amount of the Ru@ZIF-8 precursor and dissolve it in a methanol solution to form solution E; Weigh out appropriate amounts of Zn(NO3)2•6H2O and Co(NO3)2•6H2O and dissolve them in methanol solution to form solution F; The F solution was added dropwise to the E solution and stirred thoroughly at room temperature. Then, an appropriate amount of dimethylimidazole methanol solution was added dropwise and stirred thoroughly at room temperature to obtain a third suspension. The resulting third suspension was centrifuged and washed multiple times with ethanol. Finally, the washed third product was placed in a drying oven and dried at a constant temperature to obtain the Co-ZIF-8 / Ru@ZIF-8 precursor. By adjusting the ratio of Zn(NO3)2•6H2O and Co(NO3)2•6H2O, as well as the concentration of dimethylimidazole and the addition of surfactants, the morphology, phase composition, and core-shell thickness of the generated Co-ZIF-8 / Ru@ZIF-8 precursor can be controlled. S3 includes: The freeze-dried Co-ZIF-8 / Ru@ZIF-8 precursor was placed in a horizontal tube furnace and heated to 900-1000℃ at a rate of 5-10℃ / min under an inert or reducing atmosphere and held for 3-6 h to obtain RuCo@NC composite material.

2. The method for preparing the intermetallic nanocatalyst for efficient hydrogen evolution according to claim 1, characterized in that, S1.1 includes: Weigh out an appropriate amount of Zn(NO3)2•6H2O and dissolve it in a methanol solution to form solution A; Weigh out an appropriate amount of dimethylimidazole and dissolve it in methanol solution to form solution B; Add solution A dropwise to solution B and stir thoroughly at room temperature to obtain the first suspension. The first suspension was centrifuged and washed multiple times with methanol. The washed first product was then placed in a drying oven for constant temperature drying to obtain the ZIF-8 precursor.

3. The method for preparing the intermetallic nanocatalyst for efficient hydrogen evolution according to claim 2, characterized in that, The mass ratio of Zn(NO3)2•6H2O to dimethylimidazole is (1:2) to (1:3).

4. The method for preparing the intermetallic nanocatalyst for efficient hydrogen evolution according to claim 3, characterized in that, The mass ratio of Zn(NO3)2•6H2O, Co(NO3)2•6H2O and dimethylimidazole is (4:1:1.4) to (2:1:0.8).

5. A metal nanocatalyst for efficient hydrogen evolution, characterized in that, Prepared using the preparation method according to any one of claims 1 to 4.

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