Graphene / ruthenium-platinum alloy composite material, preparation method and application thereof

Abstract

The application belongs to the technical field of graphene materials, and particularly relates to a graphene / ruthenium-platinum alloy composite material, a magnetic field assisted electrodeposition preparation method thereof and application of the composite material to hydrogen evolution catalytic electrodes. The graphene / ruthenium-platinum alloy composite material is prepared by using a liquid phase reduction method to first deposit nickel nanoparticles on the surface of graphene, then using a magnetic field assisted method to electrodeposition ruthenium-platinum alloy nanoparticles on the surface of graphene, and finally corroding the nickel nanoparticles. Electrochemical measurement results show that the obtained composite material has high electrocatalytic activity and stability for hydrogen evolution reaction in alkaline and acidic electrolytes, and the electrocatalytic activity for hydrogen evolution reaction is higher than that of a commercial platinum-carbon catalyst.

Description

Technical Field

[0001] This invention belongs to the field of graphene material technology, specifically relating to a graphene / ruthenium-platinum alloy composite material, its magnetic field-assisted electrodeposition preparation method, and the application of the composite material in an electrocatalyst for hydrogen evolution reaction. Background Technology

[0002] The electrocatalyst for hydrogen evolution reaction (HEER) directly determines the hydrogen production performance of alkaline, proton exchange membrane, and anion exchange membrane water electrolyzers, thus it has numerous applications in the field of water electrolysis for hydrogen production. However, currently commercially available HEER electrocatalysts are mainly composed of noble metals (platinum, iridium, and ruthenium). Due to the high cost of noble metals, designing and preparing high-activity yet low-cost HEER electrocatalysts is of great significance. In recent years, graphene-supported ruthenium-platinum alloys have been widely studied for use as HEER electrocatalysts because graphene possesses advantages such as high conductivity, low density, and high specific surface area, and can produce a synergistic effect with ruthenium-platinum alloys. Furthermore, ruthenium is much cheaper than platinum, and its alloying with platinum can further enhance the electrocatalytic activity of the HEER. Currently, the preparation methods for graphene / ruthenium-platinum alloy composites mainly include laser ablation, hydrothermal methods, and high-temperature annealing methods. However, laser ablation requires expensive lasers, while hydrothermal methods and high-temperature annealing require high-temperature and high-pressure environments, thus posing safety risks.

[0003] In conclusion, researching a simple, low-cost, and safe process for preparing graphene-supported ruthenium-platinum alloys will be of significant technical importance. Summary of the Invention

[0004] To overcome the problems existing in the prior art, one objective of this invention is to provide a magnetic field-assisted electrodeposition method for preparing graphene / ruthenium-platinum alloy composite materials. This method utilizes a liquid-phase reduction method to first deposit nickel on the graphene surface, then uses a magnetic field-assisted method to electrodeposit ruthenium-platinum alloy nanoparticles on the graphene surface, and finally etches away the nickel nanoparticles to prepare the graphene / ruthenium-platinum composite material. This composite material exhibits high electrocatalytic activity and stability for the hydrogen evolution reaction, with its electrocatalytic activity for the hydrogen evolution reaction exceeding that of commercial iridium oxide catalysts.

[0005] To achieve the above objectives, the present invention employs the following technical solution: a magnetic field-assisted electrodeposition method for preparing graphene / ruthenium-platinum alloy composite materials, comprising the following steps:

[0006] S1. Nickel nanoparticles were first deposited on the surface of graphene using a liquid-phase reduction method to prepare a graphene / nickel composite material.

[0007] S2. After uniformly coating the graphene / nickel composite material onto the surface of nickel foam, place it in an electrodeposition solution. Place a magnet at one end of the container near the nickel foam. Under the action of the magnetic field, the graphene / nickel composite powder firmly adheres to the nickel foam. Then, ruthenium-platinum alloy nanoparticles are electrodeposited on the surface of the graphene / nickel composite powder on the nickel foam. The nickel nanoparticles are removed by chemical etching to obtain the graphene / ruthenium-platinum alloy composite material.

[0008] Further improvements to the magnetic field-assisted electrodeposition method for preparing graphene / ruthenium-platinum alloy composites:

[0009] Preferably, the specific steps of the liquid-phase reduction method in step S1 are as follows:

[0010] S11. Take an aqueous solution containing sodium citrate and nickel chloride, add graphene, stir until homogeneous to obtain a mixed solution, heat to 60-90℃ and maintain this temperature;

[0011] S12. Add hydrazine hydrate and 3M sodium hydroxide solution to the mixed solution, keep the reaction at 60-90℃ for 0.5-1.5h, wash and dry the product to obtain graphene / nickel composite powder.

[0012] Preferably, the aqueous solution in step S11 contains 0.01-0.03M sodium citrate and 0.01-0.05M nickel chloride, and the amount of graphene added to the aqueous solution is 1.0-1.5 mg / ml.

[0013] Preferably, in step S12, the volume ratio of the mixed solution, hydrazine hydrate and sodium hydroxide solution is (160-200):(2-5):(5-7.5).

[0014] Preferably, in step S2, the graphene / nickel composite material is uniformly coated onto the nickel foam, with a coating amount of 8-12 mg / cm² per unit area. 2 .

[0015] Preferably, in step S2, the graphene / nickel composite material with ruthenium-platinum alloy nanoparticles deposited on its surface is immersed in concentrated hydrochloric acid to chemically remove the nickel nanoparticles.

[0016] Preferably, in step S2, the electrodeposition solution contains 0.001-0.005M ruthenium acetate, 0.0012-0.0025M chloroplatinic acid, and 0.05-0.15M sodium citrate.

[0017] Preferably, in step S2, the current intensity of electrodeposition is 300-500mA and the electrodeposition time is 8-12min.

[0018] The second objective of this invention is to provide a graphene / ruthenium-platinum alloy composite material prepared by magnetic field-assisted electrodeposition method according to any one of the above-mentioned methods.

[0019] The third objective of this invention is to provide an application of the above-mentioned graphene / ruthenium-platinum alloy composite material in an electrocatalyst for hydrogen evolution reaction.

[0020] The advantages of this invention compared to the prior art are as follows:

[0021] This invention enables the preparation of graphene / ruthenium-platinum composite materials using an electrodeposition method. The composite material exhibits high electrocatalytic activity and stability for hydrogen evolution reactions in both alkaline and acidic electrolytes. This invention facilitates the low-cost and safe preparation of graphene / ruthenium-platinum composite materials. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the preparation process of the graphene / ruthenium platinum composite material of this invention.

[0023] Figure 2 This is a schematic diagram of the magnetic field-assisted electrodeposition process for preparing graphene / ruthenium-platinum composite materials according to the present invention.

[0024] Figure 3 This is an electron microscope image of the graphene / ruthenium platinum composite material prepared in Example 1.

[0025] Figure 4 This is an elemental mapping image of the graphene / ruthenium platinum composite material prepared in Example 1.

[0026] Figure 5 XPS spectrum of the graphene / ruthenium platinum composite material prepared in Example 1.

[0027] Figure 6 The image shows the XRD pattern of the graphene / ruthenium platinum composite material prepared in Example 1.

[0028] Figure 7 The results show the electrocatalytic performance of the graphene / ruthenium platinum composite material prepared in Example 1 in 1M KOH solution for hydrogen evolution reaction.

[0029] Figure 8 In the middle (a)-(c), the cyclic voltammetry curves of raw graphene, graphene / ruthenium prepared in Comparative Example 1, and graphene / ruthenium-platinum composite material prepared in Example 1 are respectively in 1M KOH solution at different scan rates.

[0030] Figure 9 The chronoamperometry curve of the graphene / ruthenium platinum composite material prepared in Example 1 in 1M KOH solution is shown.

[0031] Figure 10The results show the electrocatalytic performance of the graphene / ruthenium platinum composite material prepared in Example 1 in the hydrogen evolution reaction in 0.5M H2SO4 solution.

[0032] Figure 11 In the middle (a)-(c), the cyclic voltammetry curves of graphene, the graphene / ruthenium composite material prepared in Comparative Example 1, and the graphene / ruthenium-platinum composite material prepared in Example 1 are respectively in 0.5M H2SO4 solution at different scan rates.

[0033] Figure 12 The chronoamperometry curves of the graphene / ruthenium platinum composite material prepared in Example 1 in 0.5M H2SO4 solution are shown. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0035] Example 1

[0036] This embodiment provides a magnetic field-assisted electrodeposition method for preparing graphene / ruthenium-platinum alloy composite materials, specifically including the following steps:

[0037] S1. Using the liquid-phase reduction method, take 180 ml of an aqueous solution containing 0.02 M sodium citrate and 0.03 M nickel chloride, add 240 mg of graphene, stir until homogeneous to obtain a mixed solution, heat to 80 °C and maintain this temperature;

[0038] Add 3.6 ml of hydrazine hydrate and 6.6 ml of 3M sodium hydroxide solution to the mixed solution, keep the reaction at 80 °C for 1 h, wash and dry the product to obtain graphene / nickel composite powder.

[0039] S2. Apply 160 mg of graphene / nickel composite powder evenly to a 4x4 cm nickel foam, with a coating amount of 10 mg / cm². 2 The nickel foam is attached to the inner surface of the electrodeposition tank. A magnet is placed on the outside of the electrodeposition tank at a position corresponding to the electrodeposition surface of the nickel foam. Under the action of the magnetic field, the graphene / nickel composite powder is firmly attached to the nickel foam.

[0040] A mixed solution containing 0.003M ruthenium acetate, 0.0018M chloroplatinic acid, and 0.1M sodium citrate was added to the electrodeposition tank for electrodeposition. The current intensity was 400mA and the electrodeposition time was 10min. Ruthenium-platinum alloy nanoparticles were electrodeposited on the surface of graphene / nickel composite powder on nickel foam. Then, the electrodeposited product was immersed in concentrated hydrochloric acid to chemically etch away the nickel nanoparticles, thus obtaining the graphene / ruthenium-platinum alloy composite material 1.

[0041] Example 2

[0042] This embodiment provides a magnetic field-assisted electrodeposition method for preparing graphene / ruthenium-platinum alloy composite materials, specifically including the following steps:

[0043] S1. Using the liquid-phase reduction method, take 160 ml of an aqueous solution containing 0.01 M sodium citrate and 0.01 M nickel chloride, add 160 mg of graphene, stir evenly to obtain a mixed solution, heat to 60 °C and maintain this temperature.

[0044] 2 ml of hydrazine hydrate and 5 ml of 3M sodium hydroxide solution were added to the mixed solution, and the reaction was carried out at 60 °C for 0.5 h. The product was washed and dried to obtain graphene / nickel composite powder.

[0045] S2. 128 mg of graphene / nickel composite powder is uniformly coated onto a 4x4 cm nickel foam, with a coating amount of 8 mg / cm². 2 The nickel foam is attached to the inner surface of the electrodeposition tank. A magnet is placed on the outside of the electrodeposition tank at a position corresponding to the electrodeposition surface of the nickel foam. Under the action of the magnetic field, the graphene / nickel composite powder is firmly attached to the nickel foam.

[0046] A mixed solution containing 0.001M ruthenium acetate, 0.0012M chloroplatinic acid, and 0.05M sodium citrate was added to an electrodeposition tank for electrodeposition at a current intensity of 300mA for 8min. Ruthenium-platinum alloy nanoparticles were electrodeposited on the surface of graphene / nickel composite powder on nickel foam. The electrodeposited product was then immersed in concentrated hydrochloric acid to chemically remove the nickel nanoparticles, thus obtaining the graphene / ruthenium-platinum alloy composite material 2.

[0047] Example 3

[0048] This embodiment provides a magnetic field-assisted electrodeposition method for preparing graphene / ruthenium-platinum alloy composite materials, specifically including the following steps:

[0049] S1. Using the liquid-phase reduction method, take 200 ml of an aqueous solution containing 0.03 M sodium citrate and 0.05 M nickel chloride, add 300 mg of graphene, stir evenly to obtain a mixed solution, heat to 90 °C and maintain this temperature;

[0050] Add 5 ml of hydrazine hydrate and 7.5 ml of 3M sodium hydroxide solution to the mixed solution, keep the reaction at 90°C for 1.5 h, wash and dry the product to obtain graphene / nickel composite powder.

[0051] S2. 192 mg of graphene / nickel composite powder is uniformly coated onto a 4x4 cm nickel foam, with a coating amount of 12 mg / cm². 2 The nickel foam is attached to the inner surface of the electrodeposition tank. A magnet is placed on the outside of the electrodeposition tank, at a position corresponding to the electrodeposition surface of the nickel foam. The magnitude of the magnetic field force is X. Under the action of the magnetic field force, the graphene / nickel composite powder is firmly attached to the nickel foam.

[0052] A mixed solution containing 0.005M ruthenium acetate, 0.0025M chloroplatinic acid, and 0.15M sodium citrate was added to an electrodeposition tank for electrodeposition at a current intensity of 500mA for 12min. Ruthenium-platinum alloy nanoparticles were electrodeposited on the surface of graphene / nickel composite powder on nickel foam. The electrodeposited product was then immersed in concentrated hydrochloric acid to chemically remove the nickel nanoparticles, thus obtaining the graphene / ruthenium-platinum alloy composite material 3.

[0053] Comparative Example 1

[0054] This comparative example provides a method for preparing a graphene / ruthenium composite material, specifically including the following steps:

[0055] S1. Using the liquid-phase reduction method, take 180 ml of an aqueous solution containing 0.02 M sodium citrate and 0.03 M nickel chloride, add 240 mg of graphene, stir until homogeneous to obtain a mixed solution, heat to 80 °C and maintain this temperature;

[0056] Add 3.6 ml of hydrazine hydrate and 6.6 ml of 3M sodium hydroxide solution to the mixed solution, keep the reaction at 80 °C for 1 h, wash and dry the product to obtain graphene / nickel composite powder.

[0057] S2. 160mg of graphene / nickel composite powder is evenly coated on a 4x4cm foam nickel, with a coating amount of 10mg / cm2 per unit area. The foam nickel is attached to the inner surface of the electrodeposition tank. A magnet is placed on the outside of the electrodeposition tank at a position corresponding to the electrodeposition surface of the foam nickel. Under the action of the magnetic field, the graphene / nickel composite powder is firmly attached to the foam nickel.

[0058] A mixed solution containing 0.003M ruthenium acetate and 0.1M sodium citrate was added to the electrodeposition tank for electrodeposition at a current intensity of 400mA for 10min. Ruthenium nanoparticles were electrodeposited on the surface of graphene / nickel composite powder on nickel foam. The electrodeposited product was then immersed in concentrated hydrochloric acid to chemically remove the nickel nanoparticles, thus obtaining the graphene / ruthenium composite material.

[0059] Electrochemical testing:

[0060] Electrochemical measurements were performed using a three-electrode system and a Chenhua electrochemical workstation (CHI 660E). A graphite sheet served as the counter electrode, and nickel foam with graphene / ruthenium-platinum composite material loaded on its surface served as the working electrode. For 1M KOH electrolyte, a mercury / mercury oxide electrode served as the reference electrode, and for 0.5M sulfuric acid electrolyte, a mercury / mercurous sulfate electrode served as the reference electrode.

[0061] Figure 1 This is a flowchart illustrating the preparation process of the graphene / ruthenium platinum composite material of the present invention.

[0062] Figure 2 This is a schematic diagram of the magnetic field-assisted electrodeposition process for preparing graphene / ruthenium platinum composite materials according to the present invention. The graphite sheet serves as the cathode, and the nickel foam on which the graphene / nickel composite material is loaded is the anode. A magnet is placed outside the electrolytic cell at a position corresponding to the nickel foam to firmly fix the graphene / nickel composite material onto the nickel foam. The electrolyte is a mixed solution of ruthenium acetate and chloroplatinic acid.

[0063] Figure 3 The images show electron microscope (TEM) images of the graphene / ruthenium-platinum composite material prepared in Example 1. (a) is a low-magnification TEM image of the graphene / ruthenium-platinum composite material, and (b) is a high-resolution TEM image. It can be seen that platinum-ruthenium alloy nanoparticles are loaded on the graphene surface.

[0064] Figure 4 This is an elemental mapping image of the graphene / ruthenium-platinum composite material prepared in Example 1. It can be seen that ruthenium and platinum elements are uniformly distributed on the graphene surface.

[0065] Figure 5 XPS spectra of the graphene / ruthenium-platinum composite material prepared in Example 1. (a) shows the XPS spectrum of the graphene / ruthenium-platinum composite material, revealing the presence of carbon, ruthenium, and platinum. (b) is a high-resolution XPS spectrum of C1s, showing the presence of C-C bonds, CO bonds, and COOH functional groups on the graphene surface. (c) is a high-resolution XPS spectrum of Ru3p, showing that ruthenium is predominantly in a zero-valence state, indicating that ruthenium is primarily in a metallic state. (d) is a high-resolution XPS spectrum of Pt4f, showing that platinum is also predominantly in a zero-valence state, indicating that platinum is also primarily in a metallic state.

[0066] Figure 6 The image shows the XRD pattern of the graphene / ruthenium-platinum composite material prepared in Example 1. As can be seen, the composite material is mainly composed of graphene and ruthenium-platinum alloy.

[0067] Figure 7 The electrocatalytic performance test results of the graphene / ruthenium platinum composite material prepared in Example 1 for the hydrogen evolution reaction in 1M KOH solution are shown. (a) is the linear sweep voltammetry curve. It can be seen that the electrocatalytic activity of the composite material for the hydrogen evolution reaction is higher than that of graphene, graphene / ruthenium, and commercial platinum carbon. This also proves that the electrocatalytic activity of the hydrogen evolution reaction can be significantly enhanced after loading ruthenium nanoparticles and ruthenium-platinum alloy nanoparticles onto the surface of graphene. Among them, graphene, graphene / ruthenium, graphene / ruthenium platinum composite material, and commercial platinum carbon exhibit electrocatalytic activity at 10 mA cm⁻¹. -2 The overpotentials corresponding to the current densities are >250mV, 60mV, 12mV, and 28mV, respectively. (b) shows the Tafel polarization curves. The Tafel slope of the graphene / ruthenium-platinum composite is 21mV dec. -1 It is significantly smaller than graphene / ruthenium (75mV dec) -1 ) and platinum carbon (34mV dec -1 This indicates that the graphene / ruthenium-platinum composite material exhibits more favorable catalytic kinetics for hydrogen evolution reaction compared to graphene / ruthenium and platinum-carbon composites. (c) shows the electrochemical impedance spectroscopy. The interfacial charge transfer resistance (0.75 Ω) of the graphene / ruthenium-platinum alloy composite material is lower than that of graphene / nickel (1.23 Ω) and graphene (38.6 Ω). This indicates that the composite material has faster electron transport characteristics than graphene / ruthenium and graphene.

[0068] Figure 8 Figures (a)-(c) show the cyclic voltammetry curves of graphene, the graphene / ruthenium composite material prepared in Comparative Example 1, and the graphene / ruthenium-platinum composite material prepared in Example 1, respectively, in 1M KOH solution at different scan rates. Figure (d) shows the electrochemical double-layer capacitance calculated from these cyclic voltammetry curves for graphene, graphene / ruthenium, and the graphene / ruthenium-platinum composite material. The electrochemical double-layer capacitance of the graphene / ruthenium-platinum composite material is 3.1 mF cm⁻¹. -2 It is significantly greater than that of graphene / ruthenium (2.0 mF cm⁻¹). -2 ) and graphene (1.2mF cm -2 Therefore, compared with graphene / ruthenium and graphene alone, graphene / ruthenium-platinum composites have a larger electrochemical surface area and more active sites.

[0069] Figure 9The figure shows the chronoamperometry curve of the graphene / ruthenium platinum composite material prepared in Example 1 in 1M KOH solution. It can be seen that after 24 hours, the current density of the composite material only decreases slightly, indicating that the composite material has good stability in the hydrogen evolution reaction.

[0070] Figure 10 The electrocatalytic performance test results of the graphene / ruthenium-platinum composite material prepared in Example 1 for the hydrogen evolution reaction in 0.5M H2SO4 solution are shown in (a). Linear sweep voltammetry curves are also presented. It can be seen that the electrocatalytic activity of the composite material for the hydrogen evolution reaction is higher than that of graphene, graphene / ruthenium, and commercial platinum carbon. This also proves that loading ruthenium nanoparticles and ruthenium-platinum alloy nanoparticles onto the surface of graphene can significantly enhance its electrocatalytic activity for the hydrogen evolution reaction in 0.5M H2SO4 solution. Specifically, the electrocatalytic activity of graphene, graphene / ruthenium, graphene / ruthenium-platinum composite material, and commercial platinum carbon with a 10 mA cm⁻¹ is shown. -2 The overpotentials corresponding to the current densities were >250mV, 63mV, 16mV, and 29mV, respectively. (b) shows the Tafel polarization curves. The Tafel slope of the graphene / ruthenium-platinum composite material was 19mV dec. -1 It is significantly smaller than graphene / ruthenium (65mV dec) -1 ) and platinum carbon (25mV dec -1 This indicates that, compared to graphene / ruthenium and platinum-carbon composites, the graphene / ruthenium-platinum composite exhibits more favorable catalytic kinetics for hydrogen evolution in 0.5 M H₂SO₄ solution. (c) shows the electrochemical impedance spectroscopy. The interfacial charge transfer resistance of the graphene / ruthenium-platinum alloy composite (0.56 Ω) is lower than that of graphene / ruthenium (2.1 Ω) and graphene (33.3 Ω). This indicates that the composite exhibits faster electron transport characteristics in 0.5 M H₂SO₄ solution than graphene / ruthenium and graphene.

[0071] Figure 11 (a)-(c) show the cyclic voltammetry curves of graphene, the graphene / ruthenium composite material prepared in Comparative Example 1, and the graphene / ruthenium-platinum composite material prepared in Example 1, respectively, in 0.5 M H₂SO₄ solution at different scan rates. (d) shows the electrochemical double-layer capacitance calculated from these cyclic voltammetry curves for graphene, graphene / ruthenium, and the graphene / ruthenium-platinum composite material. The electrochemical double-layer capacitance of the graphene / ruthenium-platinum composite material is 4.0 mF cm⁻¹. -2 It is significantly larger than graphene / ruthenium (1.8 mF cm⁻¹). -2 ) and graphene (0.5mF ​​cm -2 Therefore, compared with graphene / ruthenium and graphene alone, the graphene / ruthenium-platinum composite exhibits a larger electrochemical surface area and more active sites in 0.5M H2SO4 solution.

[0072] Figure 12 The figure shows the chronoamperometry curve of the graphene / ruthenium platinum composite material prepared in Example 1 in 0.5M H2SO4 solution. It can be seen that after 24 hours, the current density of the composite material still maintains more than 93% of the initial current density, indicating that the graphene / ruthenium platinum composite material also has good hydrogen evolution reaction stability in 0.5M H2SO4 solution.

[0073] Following the above testing methods, the electrocatalytic performance of the graphene / ruthenium-platinum composite material prepared in Example 2 was tested for hydrogen evolution reaction. The test results are as follows:

[0074] (I) Electrocatalytic performance of hydrogen evolution reaction in 1M KOH solution

[0075] Graphene / ruthenium platinum composite material and 10 mAcm -2 The overpotential corresponding to the current density was 25 mV, higher than that of graphene / ruthenium (83 mV), commercial platinum-carbon (28 mV), and graphene (>250 mV). This demonstrates that the electrocatalytic activity of hydrogen evolution reaction can be significantly enhanced after loading ruthenium-platinum alloy nanoparticles onto the graphene surface. The Tafel slope of the graphene / ruthenium-platinum composite material was 45 mVdec. -1 It is significantly smaller than graphene / ruthenium (105mV dec) -1 This indicates that the graphene / ruthenium-platinum composite material exhibits more favorable catalytic kinetics for hydrogen evolution reaction compared to graphene / ruthenium. The interfacial charge transfer resistance of the graphene / ruthenium-platinum composite material (0.95 Ω) is lower than that of graphene / ruthenium (1.53 Ω) and graphene (38.6 Ω). This suggests that the composite material possesses faster electron transport characteristics than graphene / ruthenium and graphene alone. Furthermore, the electrochemical double-layer capacitance of the graphene / ruthenium-platinum composite material is 2.7 mF cm⁻¹. -2 It is significantly larger than graphene / ruthenium (1.6 mF cm⁻¹). -2 ) and graphene (1.2mF cm -2 Furthermore, after 24 hours, the current density of the graphene / ruthenium platinum composite material only decreased slightly, indicating that the composite material has good stability.

[0076] (II) Electrocatalytic performance of hydrogen evolution reaction in 0.5M H2SO4 solution

[0077] Graphene / ruthenium platinum composite material and 10 mAcm -2 The overpotential corresponding to the current density was 30 mV, higher than that of graphene / ruthenium (86 mV), commercial platinum-carbon (29 mV), and graphene (>250 mV). This demonstrates that the electrocatalytic activity of hydrogen evolution reaction can be significantly enhanced after loading ruthenium-platinum alloy nanoparticles onto the graphene surface. The Tafel slope of the graphene / ruthenium-platinum composite material was 45 mVdec. -1It is significantly smaller than graphene / ruthenium (98mV dec) -1 This indicates that the graphene / ruthenium-platinum composite material exhibits more favorable catalytic kinetics for hydrogen evolution reaction compared to graphene / ruthenium. The interfacial charge transfer resistance of the graphene / ruthenium-platinum composite material (0.8 Ω) is lower than that of graphene / ruthenium (2.46 Ω) and graphene (33.3 Ω). This suggests that the composite material possesses faster electron transport characteristics than graphene / ruthenium and graphene alone. Furthermore, the electrochemical double-layer capacitance of the graphene / ruthenium-platinum composite material is 3.5 mF cm⁻¹. -2 It is significantly larger than graphene / ruthenium (1.3 mF cm⁻¹). -2 ) and graphene (0.5mF ​​cm -2 Furthermore, after 24 hours, the current density of the composite material still remained at about 90% of the initial current density, indicating that the composite material has good stability.

[0078] Following the above testing methods, the electrocatalytic performance of the graphene / ruthenium-platinum composite material prepared in Example 3 was tested for hydrogen evolution reaction. The test results are as follows:

[0079] (I) Electrocatalytic performance of hydrogen evolution reaction in 1M KOH solution

[0080] Graphene / ruthenium platinum composite material and 10 mAcm -2 The overpotential corresponding to the current density was 18 mV, higher than that of graphene / ruthenium (70 mV), commercial platinum-carbon (28 mV), and graphene (>250 mV). This demonstrates that the electrocatalytic activity of hydrogen evolution reaction can be significantly enhanced after loading ruthenium-platinum alloy nanoparticles onto the graphene surface. The Tafel slope of the graphene / ruthenium-platinum composite material was 32 mVdec. -1 Smaller than graphene / ruthenium (90mV dec) -1 ) and platinum carbon (34mV dec -1 This indicates that the graphene / ruthenium-platinum composite exhibits more favorable catalytic kinetics for hydrogen evolution reaction compared to graphene / ruthenium and platinum-carbon composites. The interfacial charge transfer resistance of the graphene / ruthenium-platinum composite (0.85 Ω) is lower than that of graphene / ruthenium (1.4 Ω) and graphene (38.6 Ω). This suggests that the composite exhibits faster electron transport characteristics than graphene / ruthenium and graphene alone. Furthermore, the electrochemical double-layer capacitance of the graphene / ruthenium-platinum composite is 2.9 mF cm⁻¹. -2 It is significantly larger than graphene / ruthenium (1.8 mF cm⁻¹). -2 ) and graphene (1.2mF cm -2 Furthermore, after 24 hours, the current density of the graphene / ruthenium platinum composite material only decreased slightly, indicating that the composite material has good stability.

[0081] (II) Electrocatalytic performance of hydrogen evolution reaction in 0.5M H2SO4 solution

[0082] Graphene / ruthenium platinum composite material and 10 mAcm -2 The overpotential corresponding to the current density was 23 mV, higher than that of graphene / ruthenium (75 mV), commercial platinum-carbon (29 mV), and graphene (>250 mV). This demonstrates that the electrocatalytic activity of hydrogen evolution reaction can be significantly enhanced after loading ruthenium-platinum alloy nanoparticles onto the graphene surface. The Tafel slope of the graphene / ruthenium-platinum composite material is 30 mVdec. -1 It is significantly smaller than graphene / ruthenium (82mV dec) -1 This indicates that the graphene / ruthenium-platinum composite material exhibits more favorable catalytic kinetics for hydrogen evolution reaction compared to graphene / ruthenium. The interfacial charge transfer resistance of the graphene / ruthenium-platinum composite material (0.68 Ω) is lower than that of graphene / ruthenium (2.26 Ω) and graphene (33.3 Ω). This suggests that the composite material possesses faster electron transport characteristics than graphene / ruthenium and graphene alone. Furthermore, the electrochemical double-layer capacitance of the graphene / ruthenium-platinum composite material is 3.7 mF cm⁻¹. -2 It is significantly larger than graphene / ruthenium (1.6 mF cm⁻¹). -2 ) and graphene (0.5mF ​​cm -2 Furthermore, after 24 hours, the current density of the composite material still remained at more than 91% of the initial current density, indicating that the composite material has good stability.

[0083] In summary, the graphene / ruthenium platinum composite material prepared by this invention exhibits superior electrocatalytic activity and stability for hydrogen evolution reaction in both acidic and alkaline electrolytes.

[0084] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments. It should be noted that many modifications and improvements can be made by those skilled in the art, and all modifications or improvements not exceeding the scope of the claims should be considered within the protection scope of the present invention.

Claims

1. A method for preparing graphene / ruthenium-platinum alloy composite material by magnetic field-assisted electrodeposition, characterized in that, Includes the following steps: S1. Nickel nanoparticles were deposited on the surface of graphene using a liquid-phase reduction method to prepare a graphene / nickel composite material. S2. A graphene / nickel composite material is uniformly coated onto the surface of nickel foam, wherein the coating amount of the graphene / nickel composite material is 8-12 mg / cm³. 2 Then, the coated nickel foam is attached to the inner surface of the electrodeposition tank and placed in the electrodeposition solution, which contains 0.001-0.005 M ruthenium acetate, 0.0012-0.0025 M chloroplatinic acid, and 0.05-0.15 M sodium citrate. A magnet is placed outside the electrodeposition tank at a position corresponding to the electrodeposition surface of the nickel foam. Under the action of the magnetic field, the graphene / nickel composite material is firmly attached to the nickel foam. Ruthenium-platinum alloy nanoparticles are electrodeposited on the surface of the graphene / nickel composite material on the nickel foam. The current intensity of the electrodeposition is 300-500 mA and the electrodeposition time is 8-12 min. Chemical etching was used to remove nickel nanoparticles, resulting in a graphene / ruthenium-platinum alloy composite material.

2. The method for preparing graphene / ruthenium-platinum alloy composite material by magnetic field-assisted electrodeposition according to claim 1, characterized in that, The specific steps of the liquid-phase reduction method described in step S1 are as follows: S11. Take an aqueous solution containing sodium citrate and nickel chloride, add graphene, stir until homogeneous to obtain a mixed solution, heat to 60-90℃ and maintain this temperature; S12. Add hydrazine hydrate and 3 M sodium hydroxide solution to the mixed solution, and keep the reaction at 60-90℃ for 0.5-1.5 h. Wash and dry the product to obtain graphene / nickel composite material.

3. The method for preparing graphene / ruthenium-platinum alloy composite material by magnetic field-assisted electrodeposition according to claim 2, characterized in that, The aqueous solution in step S11 contains 0.01-0.03 M sodium citrate and 0.01-0.05 M nickel chloride, and the amount of graphene added to the aqueous solution is 1.0-1.5 mg / ml.

4. The method for preparing graphene / ruthenium-platinum alloy composite material by magnetic field-assisted electrodeposition according to claim 2, characterized in that, In step S12, the volume ratio of the mixed solution, hydrazine hydrate and sodium hydroxide solution is (160-200):(2-5):(5-7.5).

5. The method for preparing graphene / ruthenium-platinum alloy composite material by magnetic field-assisted electrodeposition according to claim 1, characterized in that, In step S2, the graphene / nickel composite material with ruthenium-platinum alloy nanoparticles deposited on its surface is immersed in concentrated hydrochloric acid to chemically remove the nickel nanoparticles.

6. A graphene / ruthenium-platinum alloy composite material prepared by magnetic field-assisted electrodeposition according to any one of claims 1-5.

7. The application of the graphene / ruthenium-platinum alloy composite material of claim 6 in an electrocatalyst for hydrogen evolution reaction in water electrolysis.

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