Preparation method of alloy film loaded noble metal electrode for alkaline hydrogen evolution

Abstract

The invention belongs to the technical field of material preparation, and discloses a preparation method of an alloy film loaded noble metal electrode for alkaline hydrogen evolution, and the preparation method comprises the following steps: firstly growing a nickel-iron alloy film on foamed nickel through constant-current deposition, then dipping in a ruthenium trichloride aqueous solution, reducing trivalent ruthenium ions into metal ruthenium under the action of the foamed nickel, and finally obtaining the metal electrode loaded with noble metal. The sample is anchored on the alloy film in the form of ruthenium nano-particle clusters, and the sample has ultralow ruthenium loading capacity. The obtained alloy film is smooth and uniform, uniform distribution of active sites is facilitated, electron transfer is accelerated, meanwhile, the ruthenium nanocluster with the proper size is loaded by controlling the dipping condition, the hydrogen evolution reaction is promoted, the hydrogen adsorption process is optimized through the synergistic effect between the ruthenium nanocluster and the nickel-iron alloy, and the hydrogen adsorption efficiency is improved. And the hydrogen evolution reaction kinetics of the material is improved. The obtained self-supporting catalyst has excellent performance which is superior to that of a Pt / C catalyst, still keeps excellent stability under industrial-grade large current density, and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of material preparation and relates to a method for preparing an alloy film-loaded noble metal electrode for alkaline hydrogen evolution. Background Art

[0002] The over-reliance of traditional energy systems on fossil fuels has caused two major global problems: the depletion of non-renewable energy and the deterioration of the ecological environment. In this context, the development of clean and renewable energy is of vital importance. Hydrogen energy has high energy density, zero carbon emissions and storability, and is a potential candidate for future low-carbon energy systems. Compared with methods such as natural gas / fossil fuel reforming to produce hydrogen, electrochemical water splitting technology uses renewable electricity to electrocatalyze water decomposition, which can achieve the sustainable preparation of green hydrogen and has the dual advantages of environmental friendliness and economy. It is worth noting that alkaline water electrolysis systems have more industrial application prospects because they avoid corrosion and safety risks in acidic media, have low cost and high stability. The hydrogen evolution reaction is a key half-reaction in water electrolysis. There are kinetic barriers in the actual water dissociation process, and under alkaline conditions, *H is obtained by the dissociation of initial water (H2O+e – →*H+OH – ), which will introduce additional energy barriers. Therefore, it is necessary to develop electrocatalysts with high activity, stability and cost-effectiveness to improve the reaction kinetics and energy conversion efficiency of alkaline hydrogen evolution reaction.

[0003] Platinum-based catalysts are classic materials for hydrogen evolution reaction, but they have inherent defects in large-scale applications: high cost, scarce reserves and poor stability. In contrast, ruthenium has great potential to replace platinum-based catalysts in alkaline hydrogen evolution reaction because of its similar hydrogen bonding energy to platinum and more significant cost advantages. Studies have confirmed that ruthenium nanoparticles anchored on carriers such as carbon materials, metals, and semi-metallic materials show excellent hydrogen evolution performance, such as the nitrogen-doped carbon-supported ruthenium ultra-small nanoparticle hydrogen evolution electrocatalyst (Ru / NC) obtained by a one-step thermal sintering method disclosed in CN118910647A. The catalyst has a hydrogen evolution rate of 10 mA cm in 1 M KOH solution. -2 The overpotential at the current density is 27mV, which is comparable to the performance of Pt / C (26mV). However, the preparation of the catalyst relies on long-term high-temperature treatment, which consumes a lot of energy. In addition, the ruthenium nanoparticles on the carbon-based material are easily detached from the carrier surface under continuous high potential, resulting in activity decay, which restricts its large-scale application under industrial high current density. CN118996494A discloses a hydrogen evolution electrocatalyst (Ru@TiC) in which ruthenium nanoparticles are loaded on titanium carbide nanofibers by electrospinning and rapid Joule heat treatment. With the help of the high specific surface area carrier and the metal-carrier interaction between ruthenium and carbide, the uniform loading of ruthenium nanoparticles and the current density exceeding 500mA cm are achieved. -2Stable hydrogen evolution performance under current density. However, the synthesis process of titanium carbide nanofibers is complex and costly, requiring the combination of multiple processes such as electrospinning and carbonization, involving high-temperature treatment and inert atmosphere control, and has high requirements for equipment. At the same time, the loading amount of ruthenium in the sample material is 0.5-30%wt., which greatly increases the cost of the catalyst. In view of the problems existing in the process of loading ruthenium nanoparticles on most carbon-based carriers, the present invention in situ grows active components on a conductive, porous three-dimensional substrate to construct a self-supporting electrode. The preparation process is simple, the traditional high-temperature treatment process is abandoned, the equipment requirements are low, the carrier and the active component are closely combined, which is conducive to the contact of electrolyte / electrocatalyst, accelerates charge transfer and maintains structural stability under high current density. By introducing iron elements to construct a nickel-iron alloy carrier, it is conducive to the uniform distribution of ruthenium nanoparticles, and adjusts the electronic structure of the nickel site, promotes the generation of hydrogen, and at the same time improves the conductivity of the material and accelerates charge transfer. In addition, the present invention reduces the loading amount of precious metals, and still maintains excellent catalytic activity under the premise of reducing the cost of the catalyst, and has both economic and large-scale application potential.

[0004] Therefore, the present invention adopts the two-step method of electrodeposition-impregnation, with nickel foam as substrate, firstly obtains a nickel-iron alloy film by electrodeposition on nickel foam, then is immersed in a ruthenium salt solution, and the nickel foam substrate reduces trivalent ruthenium ions to metallic ruthenium, and is loaded on the alloy film in the form of nanoparticle clusters, and successfully obtains an efficient hydrogen evolution electrocatalytic electrode with ultra-low ruthenium content. Wherein the smooth and uniform nickel-iron alloy film is conducive to the uniform distribution of active sites, promotes electron transfer, and the ruthenium nanoclusters with suitable sizes also have excellent hydrogen evolution performance, and the synergistic effect between ruthenium and nickel-iron alloy optimizes the hydrogen adsorption process, further improving the hydrogen evolution performance of the material. The method adopted by the present invention is simple, and reduces the cost of hydrogen evolution reaction catalyst in alkaline medium, and at an industrial current density (>500mA cm -2 ) also exhibits excellent catalytic activity and long-term stability, and has broad prospects for industrial application. Summary of the invention

[0005] The present invention aims to solve the problems that platinum-based catalysts have high costs and are difficult to maintain stability under high current density and in long-term electrocatalytic operation. The present invention provides a method for preparing an alloy film-loaded noble metal electrode for alkaline hydrogen evolution. The prepared catalytic electrode can maintain stable performance under high current density (>500mA cm -2 ) also has excellent catalytic performance and can operate stably for 50 hours.

[0006] The technical solution of the present invention:

[0007] A method for preparing an alloy film loaded with a noble metal electrode for alkaline hydrogen evolution, comprising the following steps:

[0008] (1) cutting the nickel foam, and ultrasonically cleaning in dilute hydrochloric acid, anhydrous ethanol, and deionized water in sequence to remove organic pollutants and oxides on the surface, and drying to obtain clean nickel foam;

[0009] (2) using a three-electrode system, placing clean nickel foam into an electroplating solution, and using a constant current IT method to electrodeposit a nickel-iron alloy. After completion, the nickel foam is taken out, rinsed with anhydrous ethanol and deionized water, and dried;

[0010] (3) Soaking the dried nickel foam in a ruthenium salt solution for a period of time, taking it out, rinsing it with anhydrous ethanol and deionized water, and drying it to obtain a nickel-iron alloy film loaded with precious metal electrodes.

[0011] In step (1), the molar concentration of the dilute hydrochloric acid is 1 to 6M.

[0012] In step (2), the electroplating solution is obtained by uniformly mixing deionized water, nickel salt, iron salt and sodium citrate; wherein the nickel salt is nickel chloride, nickel sulfate or nickel nitrate, and the molar concentration is 0.05-0.5M; the iron salt is ferric chloride, ferric sulfate or ferric nitrate, and the molar concentration is 5-100mM; and the molar concentration of sodium citrate is 0.05-0.5M.

[0013] In step (2), the three-electrode system uses clean nickel foam as the working electrode, a graphite rod as the counter electrode, and a saturated calomel electrode as the reference electrode, and the current density is -60 to -140 mA cm -2 , the electrodeposition time is 180 to 600 s.

[0014] In step (3), the ruthenium salt is ruthenium chloride, ruthenium nitrate or ruthenium acetate, wherein the solution concentration is 0.5 to 5 mg mL -1 ; The immersion time is 1 to 5 hours.

[0015] The alloy film loaded noble metal electrode of the present invention is used as a working electrode to form a three-electrode system for efficient hydrogen evolution reaction in an alkaline electrolyte.

[0016] Beneficial effects of the present invention:

[0017] (1) The present invention adopts a simple electrodeposition-impregnation preparation method to prepare a self-supporting electrode using a three-dimensional conductive material as a substrate, which promotes the contact between the electrolyte and the catalyst, and achieves a close combination of the active component and the substrate material through chemical bonding. The obtained electrode material has both high catalytic activity and good stability.

[0018] (2) The precious metal loading of the catalyst prepared by the present invention is less than 0.5% by weight, which reduces the amount of precious metal used and reduces the cost of the catalyst.

[0019] (3) The alloy film carrier formed on the surface of nickel foam in the present invention is smooth and uniform, which is conducive to the uniform dispersion of active sites. At the same time, the ruthenium nanoparticle clusters obtained by controlling the impregnation conditions have a suitable particle size, which accelerates the hydrogen evolution reaction. In addition, the synergistic effect between the ruthenium nanoclusters and the nickel-iron alloy optimizes the hydrogen adsorption process and further improves the performance of the material.

[0020] (4) The active components of the high-efficiency hydrogen evolution catalyst prepared by the present invention are tightly combined with the base material, so that it is not easy to fall off even at a high current density. Electrochemical tests were carried out in 1M KOH, 500mA cm -2 Only ultra-low overpotential (<150mV) is required at an industrial-grade current density, and the process can stably operate for 50 hours. The present invention provides new opportunities for hydrogen production by alkaline water electrolysis at high current density and has broad industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the preparation flow chart of the prepared Ru / NiFe / NF.

[0022] Figure 2 Scanning electron microscope images of the materials in Example 1, wherein (a) is a scanning electron microscope image of NF, (b) is a scanning electron microscope image of NiFe / NF, and (c) is a scanning electron microscope image of Ru / NiFe / NF.

[0023] Figure 3 This is a high-resolution transmission electron microscopy image of Ru / NiFe / NF prepared in Example 1.

[0024] Figure 4 (a) is the linear sweep voltammogram of Ru / NiFe / NF of Example 1, Ru / NiFe / NF-1 of Example 2, and Ru / NiFe / NF-2 of Example 3; (b) is the linear sweep voltammogram of Ru / NiFe / NF of Example 1, Ru / NiFe / NF-3 of Example 4, Ru / NiFe / NF-4 of Example 5, and Ru / NiFe / NF-5 of Example 6 in 1 M KOH solution at 25°C.

[0025] Figure 5 The linear sweep voltammograms of Ru / NiFe / NF of Example 1, Ru / NF of Comparative Example 1, Ru / Ni / NF of Comparative Example 2 and Pt / C of Comparative Example 3 in 1 M KOH solution at 25°C are shown.

[0026] Figure 6 The Tafel slope graphs of Ru / NiFe / NF of Example 1, Ru / NF of Comparative Example 1, Ru / Ni / NF of Comparative Example 2 and Pt / C of Comparative Example 3 in 1 M KOH solution at 25°C are shown.

[0027] Figure 7 The linear sweep voltammetry curve of Ru / NiFe / NF of Example 1 before and after 1000 CV scans.

[0028] Figure 8 The Ru / NiFe / NF of Example 1 was subjected to 1 M KOH solution at 25°C at -100 and -500 mA cm -2 Chronopotentiometry at current density of . DETAILED DESCRIPTION

[0029] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0030] Example 1

[0031] (1) Cut the nickel foam into 1 cm × 1.5 cm pieces and remove the surface oxides and oil stains by ultrasonic treatment in 3M HCl solution, anhydrous ethanol and deionized water for 20 min. Then, the cleaned NF was placed in a vacuum drying oven at 60 °C and dried for 6 h to obtain a clean nickel foam substrate.

[0032] (2) Dissolve 0.1 M nickel chloride, 0.01 M ferric chloride, and 0.1 M sodium citrate in 50 mL of deionized water and stir to form a uniform aqueous solution.

[0033] (3) A three-electrode system was used, the solution prepared in step (2) was used as the electroplating solution, clean nickel foam was used as the working electrode, a stone mill rod was used as the counter electrode, and a saturated calomel electrode was used as the reference electrode. The reaction was carried out at 30°C and -80 mA cm -2 The film was deposited at a constant current for 360 s, then rinsed with anhydrous ethanol and deionized water, and dried in a vacuum drying oven at 60°C for 6 h to obtain NiFe / NF.

[0034] (4) Prepare 1.5 mg mL -1 A ruthenium trichloride aqueous solution was used as the impregnation solution. The dried NiFe / NF was immersed in the impregnation solution for 2 hours, and then taken out and rinsed with anhydrous ethanol and deionized water, and dried at 60°C under vacuum conditions for 6 hours to obtain Ru / NiFe / NF.

[0035] The Ru loading of the catalyst was 0.122 mg / cm 2 , with ultra-low Ru loading.

[0036] The obtained electrode was electrochemically tested in a three-electrode system, where the graphite rod was the counter electrode, Hg / HgO was the reference electrode, the electrolyte solution was 1M KOH, and the temperature was room temperature (25°C). The starting scanning potential of the linear sweep voltammetry test (LSV) was -0.924 V (vs. Hg / HgO), and the chronopotentiometry (CP) test was performed at -100 and -500 mA cm -2 The durability test was carried out for 50 h at a current density of .

[0037] The results are as follows: Figure 2 The SEM images show that a smooth and uniform nickel-iron alloy film is uniformly grown on the NF substrate, and the ruthenium spherical nanoparticle clusters are uniformly dispersed on the NiFe / NF surface. Figure 3 This is a high-resolution transmission electron microscope image of the Ru / NiFe / NF of Example 1. Clear lattice fringes with spacings of 0.211 nm, 0.204 nm, and 0.207 nm can be observed, corresponding to the (002) and (111) planes of Ru and the (111) plane of the NiFe alloy, respectively. Figure 4 is the LSV diagram of the samples prepared in Examples 1-6, Figure 5 The LSV diagrams of the samples prepared in Example 1 and Comparative Examples 1-3 show that the Ru / NiFe / NF prepared in Example 1 has the best hydrogen evolution performance, reaching 100 and 500 mA cm -2 The current density only requires low overpotentials of 67 and 147 mV. Figure 6 The Tafel slope diagram of the samples prepared in Example 1 and Comparative Examples 1-3 shows that the Ru / NiFe / NF prepared in Example 1 has the lowest Tafel slope of 65.0 mV dec. -1 , indicating that it has faster reaction kinetics and higher catalytic activity. Figure 7 The linear sweep voltammetry curve of Ru / NiFe / NF prepared in Example 1 before and after 1000 CV scans, Figure 8 For -100 and -500 mA cm -2 From the chronopotentiometry diagram for 50 h at a current density of , it can be seen that there is no significant difference in the LSV curve of the sample before and after 1000 CV scans. In the chronopotentiometry reaction, the potential only increases slightly as the reaction proceeds, indicating that the sample has excellent stability.

[0038] Example 2

[0039] The difference between this embodiment and embodiment 1 is that the immersion time in step (4) is 1 hour, and the other parameters and specific implementation steps are the same as those in embodiment 1, and Ru / NiFe / NF-1 is obtained.

[0040] The Ru loading of the catalyst was 0.062 mg / cm 2 .

[0041] This embodiment uses the same electrochemical test method as that of embodiment 1, except that the CP test is not performed.

[0042] The results are as follows: Figure 4 (a) The Ru / NiFe / NF-1 prepared in Example 2 can reach 100 and 500 mA cm -2 The current density required for the reaction is 97 and 194 mV respectively. Compared with Example 1, the performance is poorer, which may be due to the short immersion time, the small amount of Ru loaded, the reduced active sites and the low catalytic activity.

[0043] Example 3

[0044] The difference between this embodiment and embodiment 1 is that the immersion time in step (4) is 3 hours, and the other parameters and specific implementation steps are the same as those in embodiment 1, to obtain Ru / NiFe / NF-2.

[0045] The Ru loading of the catalyst was 0.201 mg / cm 2 .

[0046] This embodiment uses the same electrochemical test method as that of embodiment 1, except that the CP test is not performed.

[0047] The results are as follows: Figure 4 (a) The Ru / NiFe / NF-2 prepared in Example 3 can reach 100 and 500 mA cm -2 The current density required was 84 and 184 mV respectively. The performance was slightly worse than that of Example 1. The reason may be that the nanoparticle clusters began to aggregate after 3 hours of immersion. Since the large-size Ru clusters have a relatively low surface atomic ratio, there are fewer active sites on the surface that can be used to bind H atoms, and the adsorption capacity for H atoms is weak, which causes the performance of the catalyst to begin to decline.

[0048] Example 4

[0049] The difference between this embodiment and embodiment 1 is that the concentration of the ruthenium trichloride aqueous solution used in step (4) is 5.0 mg / mL -1 , other parameters and specific implementation steps are the same as those in Example 1, and Ru / NiFe / NF-3 is obtained.

[0050] The Ru loading of the catalyst was 0.241 mg / cm 2 .

[0051] This embodiment uses the same electrochemical test method as that of embodiment 1, except that the CP test is not performed.

[0052] The results are as follows: Figure 4 (b) The Ru / NiFe / NF-3 prepared in Example 4 can reach 100 and 500 mA cm -2 The current density required for the catalytic reaction is 94 and 184 mV respectively. The reason for the poor performance is that the concentration of the impregnation solution is high, and too much Ru is loaded, so that a large number of nanoparticles are aggregated together, the ability to adsorb H atoms is weak, and the catalytic activity is low.

[0053] Example 5

[0054] The difference between this embodiment and embodiment 1 is that the electrodeposition time in step (3) is 600 s, and the other parameters and specific implementation steps are the same as those in embodiment 1, to obtain Ru / NiFe / NF-4.

[0055] This embodiment uses the same electrochemical test method as that of embodiment 1, except that the CP test is not performed.

[0056] The results are as follows: Figure 4 (b) The Ru / NiFe / NF-4 prepared in Example 5 can reach 100 and 500 mA cm -2 The current density required is 92 and 170 mV respectively. The performance is slightly inferior to that of Example 1, which may be due to the fact that the alloy coating is thickened due to the long electrodeposition time, the interface resistance is increased, the electron transmission path is blocked, and the catalytic activity of the material is reduced.

[0057] Example 6

[0058] The difference between this embodiment and embodiment 1 is that the molar concentration of ferric chloride in step (2) is 0.1 M, and other parameters and specific implementation steps are the same as those in embodiment 1, to obtain Ru / NiFe / NF-5.

[0059] This embodiment uses the same electrochemical test method as that of embodiment 1, except that the CP test is not performed.

[0060] The results are as follows: Figure 4 (b) The Ru / NiFe / NF-5 prepared in Example 6 can reach 100 and 500 mA cm -2 The current density required is 119 and 226 mV respectively. The main reason for the poor performance of this sample is the excessive doping of iron. When the iron content is too high, it will change the electronic structure of the alloy, weaken the mechanical stability of the material and reduce the conductivity, eventually causing the catalytic performance to decay.

[0061] Comparative Example 1

[0062] The difference between this comparative example and Example 1 is that the dried NF is directly placed in a ruthenium trichloride impregnation solution and impregnated for 2 hours to obtain Ru / NF.

[0063] This comparative example uses the same electrochemical test method as Example 1, except that the CP test is not performed.

[0064] The results are as follows: Figure 5 The LSV diagrams of the samples prepared in Example 1 and Comparative Examples 1-3 show that the Ru / NF prepared in Comparative Example 1 has a maximum of 100 and 500 mA cm -2 The current densities required high overpotentials of 268 and 358 mV, respectively. Figure 6 The Tafel slope graphs of the samples prepared in Example 1 and Comparative Examples 1-3, where the Tafel slope of Ru / NF prepared in Comparative Example 1 is 156.8 mVdec -1 It can be seen that the performance of Comparative Example 1 is much worse than that of Example 1. The reason may be that there is a synergistic effect between ruthenium and the nickel-iron alloy in Example 1, which optimizes the hydrogen adsorption process, while there is no such interaction in Comparative Example 1, resulting in its poor hydrogen evolution performance.

[0065] Comparative Example 2

[0066] The difference between this comparative example and Example 1 is that in step (2), no ferric chloride is added to the electroplating solution to obtain Ru / Ni / NF.

[0067] This comparative example uses the same electrochemical test method as Example 1, except that the CP test is not performed.

[0068] The results are as follows: Figure 5 The Ru / Ni / NF prepared in Comparative Example 2 can reach 100 and 500 mA cm -2 The current densities required higher overpotentials of 175 and 310 mV, respectively. Figure 6 The Tafel slope of Ru / Ni / NF prepared in Comparative Example 2 is 137.7 mVdec -1 . It can be seen that although the performance of Comparative Example 2 is better than that of Comparative Example 1, it is also far worse than that of Example 1. The reason may be that the Fe element is added to Example 1, and there is a bimetallic effect between the nickel-iron alloy. And the addition of iron adjusts the electronic structure of the nickel site and promotes the generation of hydrogen. In addition, the addition of a small amount of iron can improve the conductivity of the sample, thereby effectively promoting the charge transfer dynamics at the electrode interface. In contrast, the Ru / Ni / NF prepared in Comparative Example 2 does not contain iron elements, and does not have the above advantages, resulting in the overall catalytic performance being restricted.

[0069] Comparative Example 3

[0070] (1) Cut a 1 cm × 1.5 cm carbon paper (CP) and perform ultrasonic treatment twice in a mixed solution of deionized water and anhydrous ethanol (V1:V2 = 1:1) for 20 min each time to remove surface oil. Then, rinse with deionized water and dry in a vacuum drying oven at 60 °C for 6 h to obtain a clean carbon paper.

[0071] (2) 5 mg of Pt / C powder was dispersed in a mixed solution containing 460 μL of anhydrous ethanol and 40 μL of 5 wt.% Nafion117. After 30 min of ultrasonic dispersion, a uniform ink-like liquid was obtained.

[0072] (3) Use a pipette to draw 200 μL of the liquid in step (2) and apply it on an area of ​​1 cm 2 The Pt / C working electrode was obtained by drying on clean carbon paper in a vacuum drying oven at 60°C overnight.

[0073] This comparative example uses the same electrochemical test method as Example 1, except that the CP test is not performed.

[0074] The results are as follows: Figure 5 The Pt / C prepared in Comparative Example 3 can reach 100 and 500 mA cm -2 The current densities required overpotentials of 76 and 232 mV, respectively. Figure 6 The Tafel slope of Pt / C prepared in Comparative Example 3 is 74.9 mV dec -1 It can be seen that the performance of Comparative Example 3 is lower than that of Example 1, that is, the Ru / NiFe / NF prepared in Example 1 has the best catalytic performance, which is better than the commercial Pt / C hydrogen evolution catalyst.

[0075] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent transformations made using the contents of the present invention specification under the premise of the concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing an alloy film-loaded noble metal electrode for alkaline hydrogen evolution, characterized in that: Here are the steps: (1) cutting the nickel foam, and ultrasonically cleaning in dilute hydrochloric acid, anhydrous ethanol and deionized water in sequence to remove organic pollutants and oxides on the surface, and drying to obtain clean nickel foam; (2) using a three-electrode system, placing clean nickel foam into an electroplating solution, and using a constant current IT method to electrodeposit a nickel-iron alloy. After completion, the nickel foam is taken out, rinsed with anhydrous ethanol and deionized water, and dried; (3) Soaking the dried nickel foam in a ruthenium salt solution for a period of time, taking it out, rinsing it with anhydrous ethanol and deionized water, and drying it to obtain a nickel-iron alloy film loaded with precious metal electrodes.

2. The preparation method according to claim 1, characterized in that: In step (1), the molar concentration of the dilute hydrochloric acid is 1 to 6M.

3. The preparation method according to claim 1, characterized in that: In step (2), the electroplating solution is obtained by uniformly mixing deionized water, nickel salt, iron salt and sodium citrate; wherein the nickel salt is nickel chloride, nickel sulfate or nickel nitrate, and the molar concentration is 0.05-0.5M; the iron salt is ferric chloride, ferric sulfate or ferric nitrate, and the molar concentration is 5-100mM; and the molar concentration of sodium citrate is 0.05-0.5M.

4. The preparation method according to claim 1, characterized in that: In step (2), the three-electrode system uses clean nickel foam as the working electrode, a graphite rod as the counter electrode, and a saturated calomel electrode as the reference electrode, and the current density is -60 to -140 mA cm -2 , the electrodeposition time is 180 to 600 s.

5. The preparation method according to claim 1, characterized in that: In step (3), the ruthenium salt is ruthenium chloride, ruthenium nitrate or ruthenium acetate, wherein the solution concentration is 0.5 to 5 mg mL -1 ; The immersion time is 1 to 5 hours.

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