Composite material, method for its production and use as electrocatalytic material

Abstract

This application discloses a composite material, its preparation method, and its application as an electrocatalytic material. The composite material includes a support and an active component; the active component is ruthenium; it is loaded on the surface of the support in the form of nanoclusters; the size of the nanoclusters is 1-2 nm; the content of ruthenium in the composite material is 20-40 wt%; the ruthenium / graphene composite nanomaterial has the characteristics of high loading and high dispersion, and exhibits excellent hydrogen evolution performance in water electrolysis.

Description

Technical Field

[0001] This application relates to a composite material, its preparation method, and its application as an electrocatalytic material, belonging to the field of electrocatalytic materials. Background Technology

[0002] Given the severe pollution and limited resources of traditional fossil fuels, the development of small-molecule clean fuels such as H2, C2H4, and CH3OH plays a crucial role in reducing carbon emissions. In light, heat, and electrochemical conversion, electrocatalysis is the core of various energy conversion devices and a vital pathway for the rapid development of energy storage and conversion technologies. These include CO2 reduction to small organic molecules such as ethylene, nitrogen reduction to synthesize NH3, and water electrolysis for hydrogen production. Electrocatalysts play a key role in these energy conversion technologies, effectively reducing reaction activation energy and improving the rate, efficiency, and selectivity of chemical conversion.

[0003] In energy systems, hydrogen energy, with its high calorific value, light weight, pollution-free nature, and wide applicability, is considered the best alternative to fossil fuels. Hydrogen production through water electrolysis, which allows for hydrogen production under mild conditions, has attracted widespread attention as the most efficient method currently available. Furthermore, alkaline water electrolysis technology is relatively mature and has been industrialized. However, compared to acidic media, the conversion efficiency of alkaline water electrolysis is 2-3 orders of magnitude lower. Therefore, developing highly efficient and stable HER catalysts in alkaline media is a crucial step in the industrialization of water electrolysis hydrogen production technology and has become a hot research topic in this field.

[0004] To date, platinum has been widely used as a catalyst for hydrogen evolution reaction (HER) in water electrolysis due to its optimal binding affinity with hydrogen, resulting in advantages such as low overpotential, small Tafel slope, and high AC density. However, platinum's scarcity, high cost, and poor stability limit its application in HER. Therefore, exploring high-performance non-platinum noble metal (ruthenium, rhodium, iridium, and palladium) based catalysts for basic HER is currently a hot topic in materials research, including alloys, oxides, and single-atom and heteroatom-doped carbon materials. Among these, ruthenium-based nanomaterials have become an attractive HER catalyst due to their excellent catalytic activity, stability, and cost-effectiveness as a replacement for platinum-based catalysts. Summary of the Invention

[0005] Taking into account various factors, this application aims to overcome the problems of low activity, cumbersome preparation methods, and unsuitability for large-scale application of existing alkaline HER catalysts, and provides a graphene-supported ruthenium nanoclusters composite electrocatalytic material and its preparation method.

[0006] According to one aspect of this application, a composite material is provided, comprising a carrier and an active component;

[0007] The active component is ruthenium;

[0008] The active components are loaded onto the surface of the carrier in the form of nanoclusters;

[0009] The size of the nanoclusters is 1–2 nm;

[0010] The ruthenium content in the composite material is 20–40 wt%. The upper limit is selected from 40 wt%, 35 wt%, 30 wt%, and 25 wt%; the lower limit is selected from 20 wt%, 25 wt%, 30 wt%, and 35 wt%.

[0011] The carrier is graphene oxide;

[0012] The thickness of the carrier is 1–5 nm;

[0013] The support has a two-dimensional regular structure, is prepared by the Hummers method, exhibits a high oxidation state and has a regular structure, can expose more adsorption sites, and provide catalytic active centers.

[0014] Ruthenium exhibits characteristics of high loading and high dispersion.

[0015] According to another aspect of this application, a method for preparing the above-mentioned composite material is provided, comprising at least the following steps:

[0016] A solution containing ruthenium precursor raw material is mixed with a dispersion containing a carrier to obtain a mixed solution, which is then freeze-dried and annealed to obtain the composite material.

[0017] The ruthenium precursor is selected from ruthenium trichloride;

[0018] In the solution containing ruthenium precursor raw material, the concentration of ruthenium precursor is 10-100 g / L, and the remainder is water; the upper limit of the concentration of ruthenium precursor is selected from 100 g / L, 90 g / L, 80 g / L, 70 g / L, 60 g / L, 50 g / L, 40 g / L, 30 g / L, and 20 g / L; the lower limit is selected from 10 g / L, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, and 90 g / L.

[0019] The dispersion containing the carrier has a carrier concentration of 0.5–5 g / L, with the remainder being water. The upper limit of the carrier concentration is selected from 5 g / L, 4.5 g / L, 4 g / L, 3.5 g / L, 3 g / L, 2.5 g / L, 2 g / L, 1.5 g / L, and 1 g / L; the lower limit is selected from 0.5 g / L, 1 g / L, 1.5 g / L, 2 g / L, 2.5 g / L, 3 g / L, 3.5 g / L, 4 g / L, and 4.5 g / L.

[0020] In the mixed solution, the mass ratio of the ruthenium precursor to the carrier is 50-100 mg: 80-100 mg.

[0021] The mixing is performed by dropwise addition;

[0022] The land price process includes at least the following steps: adding the solution containing the ruthenium precursor raw material dropwise to a dispersion containing a carrier;

[0023] The dripping time is 5 to 20 minutes.

[0024] The pH of the mixed solution is 7–13.

[0025] The freeze-drying temperature is -100 to -25°C;

[0026] The pressure for freeze drying is 10–40 Pa;

[0027] The freeze-drying time is 1 to 5 days.

[0028] The annealing temperature is 200–500°C;

[0029] The annealing time is 2 to 10 hours;

[0030] The annealing atmosphere is a non-reactive gas atmosphere;

[0031] The inactive gas is selected from at least one of nitrogen, helium, or argon.

[0032] Specifically, including:

[0033] A precursor solution was prepared by uniformly mixing a ruthenium precursor with a graphene oxide dispersion. The pH of the precursor solution was adjusted to 7-13 using ammonia. The mixed solution was then dried, and the dried solid was annealed under inactive gas conditions to obtain the two-dimensional composite material.

[0034] The ruthenium precursor is selected from ruthenium trichloride, ruthenium trichloride hydrate, or ruthenium acetylacetone.

[0035] The solvent for the graphene oxide dispersion is water with a concentration of 0.5–5 g / L; the solvent for the solution containing the ruthenium precursor is water with a concentration of 10–100 g / L; and the concentration of ammonia is 2–8 mol / L.

[0036] The drying process is freeze drying, which is performed using liquid nitrogen in a freeze dryer.

[0037] The freeze-drying conditions are as follows: drying temperature is -100 to -25°C; drying pressure is 10 to 40 Pa; and drying time is 1 to 5 days.

[0038] The annealing temperature can be 200-500℃, and the holding time can be 2-10 hours. Annealing can make the ruthenium on the surface form stable nanoclusters, which improves the overall stability of the material.

[0039] The inert atmosphere is nitrogen or argon.

[0040] According to another aspect of this application, an electrocatalytic material is provided, comprising the composite material described above or the composite material prepared by the preparation method described above.

[0041] The electrocatalytic material was used in a 1 mol / L KOH electrolyte at a current density of 10 mA cm⁻¹. -2 The overpotential is 13mV, and the stable operating time is 30h.

[0042] The advantages of this application are:

[0043] The Ru / C composite material described in this application was prepared by ion adsorption using the abundant functional groups on the surface of graphene oxide to stabilize ruthenium nanoclusters. Graphene oxide is an excellent two-dimensional support, which is beneficial for the loading of ruthenium nanoclusters. A synergistic catalytic effect is formed between the ruthenium nanoclusters and the graphene oxide support, and the highly dispersed metal sites can effectively improve the activity and stability of the hydrogen evolution reaction. The composite material of this application exhibits a stability at 10 mA cm⁻¹. -2 The overpotential at the current density is only 13mV, which is superior to commercial Pt / C. More importantly, it exhibits excellent catalytic stability during long-term electrocatalysis of 30h. Its high catalytic activity and high stability are mainly due to the synergistic catalytic effect between ruthenium and graphene support.

[0044] The preparation method described in this application aims to further explore two-dimensional composite materials that are low-cost, simple to implement, and have excellent performance. First, a graphene oxide dispersion with a high degree of oxidation is synthesized using the Hummers method. This dispersion is then used as a carrier to adsorb ruthenium metal ions. The pH of the mixture is adjusted using ammonia water, and the precursor powder is obtained after freeze-drying. Finally, the precursor is annealed at 200–500 °C to obtain a highly loaded and highly dispersed ruthenium nanoclusters / graphene two-dimensional composite material. This material exhibits a smooth two-dimensional structure, a large specific surface area, and uniform distribution, making it an excellent two-dimensional electrocatalytic composite material.

[0045] Ruthenium / graphene composite materials synthesized using an ion adsorption-pyrolysis method are simple and easy to implement. The materials have advantages such as high loading capacity, small particle size, uniform distribution, regular structure, and large specific surface area, which are conducive to electron transport and mass diffusion. They exhibit excellent activity and stability, making them easy to promote and apply, and further promoting the industrialization of water electrolysis. Attached Figure Description

[0046] Figure 1 This is a flowchart illustrating the preparation process of the ruthenium / graphene composite material according to Example 1 of this application.

[0047] Figure 2 This is an X-ray diffraction pattern of the ruthenium / graphene composite material according to Example 1 of this application.

[0048] Figure 3 This is a scanning electron microscope image of the ruthenium / graphene composite material according to Example 1 of this application.

[0049] Figure 4 This is a transmission electron microscope (TEM) image of the ruthenium / graphene composite material according to Example 1 of this application.

[0050] Figure 5 This is an atomic force microscope image of the ruthenium / graphene composite material according to Example 1 of this application.

[0051] Figure 6 The graph shows the performance of the ruthenium / graphene composite material and commercial Pt / C in the electrocatalytic water splitting and hydrogen evolution according to Example 1 of this application. The electrolyte is a 1M KOH aqueous solution.

[0052] Figure 7 The stability curve of the ruthenium / graphene composite material according to Example 1 of this application after 30 hours of continuous operation is shown. Detailed Implementation

[0053] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0054] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased commercially. Ruthenium chloride and ruthenium trichloride hydrate were purchased from Tianjin Jinbolan Fine Chemical Co., Ltd.; graphene oxide was prepared by the Hummers process.

[0055] The analysis method in the embodiments of this application is as follows:

[0056] The X-ray diffraction pattern testing method is as follows: powder samples are tested using an X-ray diffractometer (model: Smatlab).

[0057] The method for testing two-dimensional material scanning electron microscopy images is as follows: powder samples are tested using a scanning electron microscope (model JSM-7900F).

[0058] The transmission electron microscopy (TEM) method is as follows: powder samples are tested using a TEM (model HT7700).

[0059] The atomic force microscopy testing method is as follows: using an atomic force microscope (model Dimension Icon), the sample is dispersed on a silicon wafer for testing.

[0060] The test method for electrocatalytic hydrogen evolution performance is as follows: powder sample testing is performed using an electrochemical workstation (model: CHI760E).

[0061] Example 1: Preparation method of ruthenium / graphene nanocomposite material

[0062] Figure 1 A flowchart illustrating the preparation process of ruthenium / graphene nanocomposites is shown. Figure 1 The process flow shown is used to prepare ruthenium / graphene two-dimensional materials. The specific operation steps are as follows:

[0063] (1) Prepare a 1 mg / mL graphene oxide solution using deionized water, 15 mL.

[0064] (2) Prepare a ruthenium trichloride hydrate solution with a concentration of 20 mg / mL using deionized water, 0.375 mL.

[0065] (3) Add the ruthenium trichloride hydrate solution dropwise into the graphene oxide solution over a period of 10 minutes. Stir at room temperature for 20 minutes to allow the ruthenium trichloride to be adsorbed onto the graphene oxide surface, thus obtaining a precursor mixed solution.

[0066] (4) Slowly add 4 mol / L ammonia solution dropwise into the precursor mixture, adjust the pH to 9, and stir at room temperature for 10 minutes.

[0067] (5) The mixed solution from step (4) was frozen into ice blocks using liquid nitrogen. The resulting ice blocks were then placed in a freeze dryer to remove moisture from the solid, yielding a solid ruthenium trichloride hydrate / graphene oxide two-dimensional material. The freeze dryer was set at -50°C and 23 Pa for 2 days.

[0068] (6) The ruthenium trichloride hydrate / graphene oxide two-dimensional material obtained in step (5) is placed in a tube furnace, protected with argon, annealed at 300°C for 4 hours, to obtain a ruthenium / graphene nanocomposite material. The mass ratio of graphene to ruthenium in the ruthenium / graphene composite material is 2:3.

[0069] The composite catalytic material prepared according to the above process has a two-dimensional structure, with nanosheets having a thickness of 1–5 nm and nanoclusters having a size of 1–2 nm. This material exhibits excellent electrocatalytic hydrogen evolution activity and good cycling and continuous operating stability in a N2-saturated 1M KOH solution.

[0070] Example 2: Preparation method of ruthenium / graphene nanocomposite material

[0071] (1) Prepare a 1 mg / mL graphene oxide solution using deionized water, 15 mL.

[0072] (2) Prepare a ruthenium trichloride hydrate solution with a concentration of 20 mg / mL using deionized water, 0.375 mL.

[0073] (3) Add the ruthenium trichloride hydrate solution dropwise into the graphene oxide solution over a period of 10 minutes. Stir at room temperature for 20 minutes to allow the ruthenium trichloride to be adsorbed onto the graphene oxide surface, thus obtaining a precursor mixed solution.

[0074] (4) Slowly add 4 mol / L ammonia solution dropwise into the precursor mixture, adjust the pH to 7, and stir at room temperature for 10 minutes.

[0075] (5) The mixed solution from step (4) was frozen into ice blocks using liquid nitrogen. The resulting ice blocks were then placed in a freeze dryer to remove moisture from the solid, yielding a solid ruthenium trichloride hydrate / graphene oxide two-dimensional material. The freeze dryer was set at -50°C and 23 Pa for 2 days.

[0076] (6) The ruthenium trichloride hydrate / graphene oxide two-dimensional material obtained in step (5) is placed in a tube furnace, protected with argon, annealed at 200°C for 3 hours, to obtain a ruthenium / graphene nanocomposite material. The mass ratio of graphene to ruthenium in the ruthenium / graphene composite material is 2:3.

[0077] Example 3: Preparation method of ruthenium / graphene nanocomposite material

[0078] (1) Prepare a graphene oxide solution with a concentration of 6 mg / mL using deionized water, 10 mL.

[0079] (2) Prepare a ruthenium trichloride hydrate solution with a concentration of 50 mg / mL using deionized water, 0.6 mL.

[0080] (3) Add the ruthenium trichloride hydrate solution dropwise into the graphene oxide solution over a period of 10 minutes. Stir at room temperature for 20 minutes to allow the ruthenium trichloride to be adsorbed onto the graphene oxide surface, thus obtaining a precursor mixed solution.

[0081] (4) Slowly add 4 mol / L ammonia solution dropwise into the precursor mixture, adjust the pH to 12, and stir at room temperature for 10 minutes.

[0082] (5) The mixed solution from step (4) was frozen into ice blocks using liquid nitrogen. The resulting ice blocks were then placed in a freeze dryer to remove moisture from the solid, yielding a solid ruthenium trichloride hydrate / graphene oxide two-dimensional material. The freeze dryer was set at -50°C and 23 Pa for 2 days.

[0083] (6) The ruthenium trichloride hydrate / graphene oxide two-dimensional material obtained in step (5) is placed in a tube furnace, protected with nitrogen, annealed at 400°C for 10 hours, to obtain a ruthenium / graphene nanocomposite material. The mass ratio of graphene to ruthenium in the ruthenium / graphene composite material is 1:2.

[0084] Example 4: Preparation method of ruthenium / graphene nanocomposite material

[0085] (1) Prepare a graphene oxide solution with a concentration of 6 mg / mL using deionized water, 10 mL.

[0086] (2) Prepare a ruthenium trichloride hydrate solution with a concentration of 50 mg / mL using deionized water, 0.8 mL.

[0087] (3) Add the ruthenium trichloride hydrate solution dropwise into the graphene oxide solution over a period of 10 minutes. Stir at room temperature for 20 minutes to allow the ruthenium trichloride to be adsorbed onto the graphene oxide surface, thus obtaining a precursor mixed solution.

[0088] (4) Slowly add 4 mol / L ammonia solution dropwise into the precursor mixture, adjust the pH to 9, and stir at room temperature for 10 minutes.

[0089] (5) The mixed solution from step (4) was frozen into ice blocks using liquid nitrogen. The resulting ice blocks were then placed in a freeze dryer to remove moisture from the solid, yielding a solid ruthenium trichloride hydrate / graphene oxide two-dimensional material. The freeze dryer was set at -50°C and 23 Pa for 2 days.

[0090] (6) The ruthenium trichloride hydrate / graphene oxide two-dimensional material obtained in step (5) is placed in a tube furnace, protected with argon, annealed at 200°C for 10 hours, to obtain a ruthenium / graphene nanocomposite material. The mass ratio of graphene to ruthenium in the ruthenium / graphene composite material is 2:3.

[0091] Analysis example

[0092] The ruthenium / graphene composite material prepared in Example 1 was analyzed.

[0093] The ruthenium / graphene two-dimensional material prepared in Example 1 was analyzed using an X-ray diffractometer. The obtained X-ray diffraction pattern is shown below. Figure 2 As shown. Figure 2 Only carbon-graphite-carbon diffraction peaks are shown. According to the Scherrer equation, the small size of ruthenium nanoparticles leads to a wider band of metal diffraction spectrum.

[0094] The ruthenium / graphene composite material in Example 1 was characterized by scanning electron microscopy, and the results are shown in the figure. Figure 3 ,Depend on Figure 3It is known that the ruthenium / graphene composite material has a regular two-dimensional structure with nanosheets having a thickness of 1–5 nm.

[0095] The ruthenium / graphene composite material in Example 1 was characterized by transmission electron microscopy, and the results are shown in the figure. Figure 4 , Figure 4 This indicates that highly dispersed ruthenium nanoclusters are uniformly distributed on the surface of graphene oxide, with particle sizes ranging from 1 to 2 nm.

[0096] The ruthenium / graphene composite material in Example 1 was characterized by atomic force microscopy, and the results are shown in [Figure 1]. Figure 5 ,Depend on Figure 5 It can be seen that the ruthenium / graphene composite material has a regular two-dimensional structure with a thickness of 3 nm.

[0097] Test Example 1

[0098] The performance of the ruthenium / graphene composite material prepared in Example 1 was tested.

[0099] The electrocatalytic hydrogen evolution performance of the ruthenium / graphene composite material prepared in Example 1 was tested using a CHI760 electrochemical workstation. The electrolyte was a nitrogen-saturated 1M NaOH or 1M KOH alkaline solution. A standard three-electrode system was used, consisting of: a working electrode prepared by mixing 4 mg Ru / C powder with 0.5 ml water and 0.5 ml ethanol to a concentration of 4 mg / mL; 20 μL of the catalyst solution was coated onto a glassy carbon electrode as the working electrode; a graphite rod was used as the counter electrode; and Ag / AgCl was used as the reference electrode. Activity was tested using a linear sweep voltammetry method at a scan rate of 10 mV / s. Stability was tested using a chronoamperometry method at a voltage of 13 mV for 30 hours. The hydrogen evolution performance test results are as follows: Figure 6 , 7 As shown, Figure 6 The linear sweep voltammetry curves of ruthenium / graphene composite material and commercial platinum / carbon in alkaline solution show that ruthenium / graphene exhibits a higher exchange current density at the same voltage. Figure 7 This indicates that the ruthenium / graphene composite material can still maintain good cycle stability under 30h working conditions, achieving efficient and stable electrocatalytic hydrogen evolution in alkaline electrolyte.

[0100] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A composite material, characterized by, Includes carrier and active component; The active component is ruthenium atoms; The active component is loaded onto the surface of the carrier in the form of nanoclusters, and the size of the nanoclusters is 1~2 nm. The carrier is graphene; The thickness of the carrier is 1~5nm; The carrier has a two-dimensional regular structure. The method for preparing the composite material includes at least the following steps: A solution containing ruthenium precursor raw material is mixed with a dispersion containing a carrier to obtain a mixed solution, which is then freeze-dried and annealed to obtain the composite material. The pH of the mixed solution is 7-13, and the pH is adjusted using ammonia. The annealing temperature is 200~500℃; The annealing atmosphere is a non-reactive gas atmosphere.

2. The composite material according to claim 1, characterized in that, The ruthenium content in the composite material is 20-40 wt%.

3. The composite material according to claim 1, characterized in that, The ruthenium precursor is selected from ruthenium trichloride; In the solution containing ruthenium precursor raw material, the concentration of ruthenium precursor is 10~100 g / L, and the remainder is water; In the dispersion containing the carrier, the concentration of the carrier is 0.5~5 g / L, and the remainder is water; In the mixed solution, the mass ratio of the ruthenium precursor to the carrier is 50~100mg:80~100mg.

4. The composite material according to claim 1, characterized in that, The mixing is performed by dropwise addition; The dropwise addition process includes at least: adding the solution containing the ruthenium precursor raw material dropwise to the dispersion containing the carrier; The dripping time is 5-20 minutes.

5. The composite material according to claim 1, characterized in that, The freeze-drying temperature is -100~-25℃; The pressure for freeze drying is 10~40 Pa; The freeze-drying time is 1 to 5 days.

6. The composite material according to claim 1, characterized in that, The annealing time is 2-10 hours; The inactive gas is selected from at least one of nitrogen, helium, or argon.

7. An electrocatalytic material, characterized in that, Includes the composite material described in claim 1.

8. The electrocatalytic material according to claim 7, characterized in that, The overpotential of the electrocatalytic material is 13 mV when the current density is 10 mA cm -2 in 1 mol / L KOH electrolyte, and the stable working operation time is ≥30 h.

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