Preparation method of ruthenium-manganese alloy catalytic material and ruthenium-manganese alloy catalytic material

Abstract

The invention discloses a preparation method of a ruthenium-manganese alloy catalytic material, which comprises the following steps: adding ruthenium chloride, manganese acetate and cetyltrimethylammonium bromide into a polyacrylonitrile solution with the mass fraction of 10-12% (the solvent is N, N-dimethylformamide), the mass ratio of ruthenium chloride to polyacrylonitrile is 1: 15, and the mass ratio of manganese acetate to ruthenium chloride is (1-5): 1; the self-supporting RuMn alloy catalyst (C (at) RuMn / CNFs) is prepared by utilizing electrostatic spinning and high-temperature carbonization, and the RuMn alloy particles are wrapped by a plurality of carbon layers, so that the method has the advantages of no need of adopting a binder, no covering of catalytic active sites and no shedding of the RuMn catalyst.

Description

Technical Field

[0001] The invention relates to the technical field of catalytic hydrogen production by water electrolysis, and in particular to a preparation method of a ruthenium-manganese alloy catalytic material and the ruthenium-manganese alloy catalytic material. Background Art

[0002] As the ideal final energy source at this stage, hydrogen energy is expected to solve energy and environmental problems. At present, researchers have developed a variety of hydrogen production technologies for the production of hydrogen energy, such as water electrolysis, biological hydrogen production, and photolysis of water. Electrolysis of water to produce hydrogen is a hydrogen production technology with great development potential due to its simple technology and green environmental protection. However, due to the solution resistance and electrode resistance, the actual voltage required for water electrolysis is much greater than the theoretical value of 1.23V. Therefore, catalysts play an important role in water electrolysis. At present, Pt / C is the most excellent commercial hydrogen evolution catalyst. However, the high price of Pt limits its large-scale application. It is imperative to develop low-cost catalysts.

[0003] Ru has a similar hydrogen intermediate binding energy to Pt, but its price is lower than that of Pt. Therefore, it is a precious metal catalyst with great application prospects. Among the various valence states of Ru, metallic Ru (0) is a relatively stable state and has the best catalytic activity. In the process of preparing metallic Ru-based catalysts, high-temperature heat treatment technology is usually required to thermally reduce the Ru element to metallic Ru. In this process, metallic Ru inevitably aggregates. This is not conducive to maximizing the utilization of the active sites of the Ru element. In this regard, researchers usually use some carriers, such as metals, oxides, carbon substrates, etc., to load the Ru element. This effectively avoids the transition aggregation of the Ru element, making the Ru element more evenly dispersed on the carrier, maximizing the catalytic activity of the metallic Ru. For example, examples 1-2. In the HER process, because the precious metal Ru has good antioxidant properties, it is not easily oxidized and maintains good catalytic activity. However, the metal carrier is prone to redox reaction denaturation, covering the active sites of the metallic Ru. In contrast, in addition to excellent conductivity, the carbon carrier also has good mechanical and electrochemical stability, because carbon hardly participates in the water decomposition reaction, or requires considerable energy to participate.

[0004] Moreover, for non-self-supporting electrodes, organic binders are required without exception, which can easily cause the catalyst to fall off due to unstable adhesion, or reduce the utilization rate of active sites due to the binder covering the catalyst. Self-supporting electrodes do not require the use of binders and can be directly used as electrodes for reactions.

[0005] Disadvantages of current non-self-supporting water electrolysis catalysts:

[0006] 1. Commercial Pt / C catalysts are expensive;

[0007] 2. Most catalysts are in the form of powders, which need to be coated on substrates such as carbon cloth, carbon paper, and nickel foam using organic binders. However, organic binders have poor conductivity and can also cover catalytic active sites.

[0008] 3. After the catalyst is coated on the substrate and catalysis begins, the impact force of the generated bubbles will cause the catalyst to fall off. Summary of the invention

[0009] The purpose of the present invention is to solve the problems in the prior art and to provide a preparation method of a ruthenium-manganese alloy catalyst material and a ruthenium-manganese alloy catalyst material.

[0010] In order to achieve the above object, the technical solution of the present invention is:

[0011] A method for preparing a ruthenium-manganese alloy catalyst material comprises the following steps:

[0012] S1. adding ruthenium chloride, manganese acetate and cetyltrimethylammonium bromide (CTAB) to a 10-12% polyacrylonitrile solution (solvent is N,N-dimethylformamide), wherein the mass ratio of cetyltrimethylammonium bromide to polyacrylonitrile is 1:8, the mass ratio of ruthenium chloride to polyacrylonitrile is 1:15, and the mass ratio of manganese acetate to ruthenium chloride is 1-5:1;

[0013] S2. Stir the above solution for at least 3 hours until the solution is uniform;

[0014] S3. Pour the prepared solution into a syringe and perform electrospinning in an electrospinning machine at a voltage of 15-20 kV to obtain a RuMn / PAN precursor fiber membrane;

[0015] S4. The prepared RuMn / PAN precursor fiber membrane is pre-oxidized in a tube furnace, the temperature is raised to 200-300°C, and kept warm for at least 1h;

[0016] S5. Raise the temperature to 800-1100°C at a rate of 5°C / min and keep it warm for at least 1h under inert gas conditions. After cooling to room temperature, C@RuMn / CNFs are obtained.

[0017] Preferably, the voltage of the electrospinning machine in step S3 is 18 kV.

[0018] Preferably, the temperature of the tube furnace in step S4 is 230°C.

[0019] Preferably, the inert gas in step S5 is argon or nitrogen.

[0020] A ruthenium-manganese alloy catalytic material is prepared by the above method.

[0021] The beneficial effects of the present invention are:

[0022] The present invention discloses a method for preparing a ruthenium-manganese alloy catalyst material. The self-supporting RuMn alloy catalyst (C@RuMn / CNFs) is prepared by electrospinning and high-temperature carbonization, and the RuMn alloy particles are wrapped with multiple carbon layers. The method has the advantages of not requiring the use of a binder, not covering the catalytic active sites, and not causing the RuMn catalyst to fall off. Compared with commercial Pt / C catalysts, the catalytic activity and catalytic stability are better. At 100 mA / cm 2 At a current density of 1.5 Å, the overpotential of RuMn / CNFs was as low as 80 mV, while that of Pt / C electrode was 100 mV. In the stability test, the catalytic stability of Pt / C electrode dropped sharply within 2 h, with a potential change of up to 330 mV, while the potential change of RuMn / CNFs was only 100 mV after 100 h of continuous operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a scanning electron microscope image of the ruthenium-manganese alloy catalyst material of the present invention;

[0024] Figure 2 To invent the XRD diagram of the crystal structure of ruthenium-manganese alloy catalyst material;

[0025] Figure 3 (a) EDS mapping image and (b) EDS line scan of C@RuMn / CNFs (recording the area indicated by the red line in the inset);

[0026] Figure 4 The voltage-current density diagram of the ruthenium-manganese alloy catalyst material and the Pt / C electrode of the present invention;

[0027] Figure 5 The voltage-current density diagram of ruthenium-manganese alloy catalyst materials prepared with different ratios of Ru to Mn;

[0028] Figure 6 It is a time-voltage diagram of the ruthenium-manganese alloy catalyst material and the Pt / C electrode under a constant voltage. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0030] Example 1

[0031] Preparation method of C@RuMn / CNFs: 0.5mmol ruthenium chloride, 0.5mmol manganese acetate, 0.12g hexadecyltrimethylammonium bromide (CTAB) and 1.5g polyacrylonitrile (PAN) were added to 13.5g N,N-dimethylformamide (DMF) and stirred for 12h. Then, electrospinning was performed at a spinning rate of 0.5mL / h under 18kV voltage in an electrospinning machine. After 20h of spinning, RuMn / PAN precursor fiber membrane was obtained. Next, the prepared RuMn / PAN was pre-oxidized in a tubular furnace, and the temperature was raised to 230℃ and maintained for 3h. Then, the temperature was raised to 1000℃ at a rate of 5℃ / min and kept warm for 3h under argon conditions. After cooling to room temperature, C@RuMn / CNFs were obtained.

[0032] Example 2

[0033] Preparation method of C@RuMn / CNFs: 0.5mmol ruthenium chloride, 1.5mmol manganese acetate, 0.12g hexadecyltrimethylammonium bromide (CTAB) and 1.5g polyacrylonitrile (PAN) were added to 13.5g N,N-dimethylformamide (DMF) and stirred for 12h. Then, electrospinning was performed at a spinning rate of 0.5mL / h under a voltage of 18kV in an electrospinning machine. After 20h of spinning, RuMn / PAN precursor fiber membrane was obtained. Next, the prepared RuMn / PAN was pre-oxidized in a tubular furnace, and the temperature was raised to 230℃ and maintained for 3h. Then, the temperature was raised to 1000℃ at a rate of 5℃ / min and kept warm for 3h under argon conditions. After cooling to room temperature, C@RuMn / CNFs were obtained.

[0034] Example 3

[0035] Preparation method of C@RuMn / CNFs: 0.5mmol ruthenium chloride, 2.5mmol manganese acetate, 0.12g hexadecyltrimethylammonium bromide (CTAB) and 1.5g polyacrylonitrile (PAN) were added to 13.5g N,N-dimethylformamide (DMF) and stirred for 12h. Then, electrospinning was performed at a spinning rate of 0.5mL / h under a voltage of 18kV in an electrospinning machine. After 20h of spinning, RuMn / PAN precursor fiber membrane was obtained. Next, the prepared RuMn / PAN was pre-oxidized in a tubular furnace, and the temperature was raised to 230℃ and maintained for 3h. Then, the temperature was raised to 1000℃ at a rate of 5℃ / min and kept warm for 3h under argon conditions. After cooling to room temperature, C@RuMn / CNFs were obtained.

[0036] Example 4

[0037] Preparation method of C@RuMn / CNFs: 0.5mmol ruthenium chloride, 1.5mmol manganese acetate, 0.12g hexadecyltrimethylammonium bromide (CTAB) and 1.5g polyacrylonitrile (PAN) were added to 13.5g N,N-dimethylformamide (DMF) and stirred for 12h. Then, electrospinning was performed at a spinning rate of 0.5mL / h under a voltage of 15kV in an electrospinning machine. After 20h of spinning, RuMn / PAN precursor fiber membrane was obtained. Next, the prepared RuMn / PAN was pre-oxidized in a tubular furnace, and the temperature was raised to 200℃ and maintained for 3h. Then, the temperature was raised to 800℃ at a rate of 5℃ / min and kept warm for 3h under argon. After cooling to room temperature, C@RuMn / CNFs were obtained.

[0038] Example 5

[0039] Preparation method of C@RuMn / CNFs: 0.5mmol ruthenium chloride, 1.5mmol manganese acetate, 0.12g hexadecyltrimethylammonium bromide (CTAB) and 1.5g polyacrylonitrile (PAN) were added to 13.5g N,N-dimethylformamide (DMF) and stirred for 12h. Then, electrospinning was performed at a spinning rate of 0.5mL / h at a voltage of 20kV in an electrospinning machine. After 20h of spinning, RuMn / PAN precursor fiber membrane was obtained. Next, the prepared RuMn / PAN was pre-oxidized in a tubular furnace, and the temperature was raised to 300℃ and maintained for 3h. Then, the temperature was raised to 1100℃ at a rate of 5℃ / min and kept warm for 3h under nitrogen conditions. After cooling to room temperature, C@RuMn / CNFs were obtained.

[0040] Comparative Example

[0041] Preparation of Pt / C electrode: 3 mg of commercial Pt / C powder was added to 1 mL of mixed solution (40 μL Nafion solution, 750 μL isopropanol, 210 μL deionized water). Ultrasonic dispersion was performed for 30 min. Subsequently, 100 μL of the suspension was added to a 1×1 cm 2 carbon paper substrate and allowed to dry naturally for 24 hours.

[0042] Take the C@RuMn / CNFs sample prepared in Example 2 as an example.

[0043] like Figure 1 As shown, the prepared C@RuMn / CNFs is a structure in which uniform particles are loaded on carbon nanofibers.

[0044] in Figure 2 The XRD pattern of the material shows that the material contains the metal peak of Ru and the peak of graphite carbon. This confirms that the fiber is a carbon nanofiber.

[0045] In addition, the element distribution on the random nanoparticles on the carbon fiber was further characterized, such as Figure 3 As shown, the EDS results on the entire surface of the particles and the line scan-EDS results on the particles show that the distribution of Ru and Mn elements on the surface of the nanoparticles is uniform. Therefore, combined with the XRD results, it can be confirmed that the nanoparticles are RuMn alloys with Ru metal phase as the main component.

[0046] The hydrogen evolution performance of the C@RuMn / CNFs sample prepared in Example 2 was compared with that of the commercial Pt / C electrode in the comparative example. The test conditions are as follows: All electrochemical tests were carried out in an electrolytic cell with an electrolyte of 1M KOH using a CHI electrochemical workstation (CHI Instruments 660E, China). The electrolytic cell uses a standard three-electrode system, with the self-synthesized electrocatalyst as the working electrode, the Hg / HgO electrode as the reference electrode, and graphite rods as the counter electrode. In this experiment, all electrochemical test potentials were converted using a reversible hydrogen electrode (RHE) according to the Nernst equation: E(vs.RHE)=E(vs.Hg / HgO)+0.059×pH+0.098V. The polarization curve (LSV) was tested at a scan rate of 2mV / s. The material stability test results are recorded at a constant voltage, and the current density-time curve. The test results are as follows Figure 4 As shown, the drive is 100mA / cm 2 For the current density, the Pt / C electrode requires an overpotential of 140 mV, while the C@RuMn / CNFs only requires an overpotential of 80 mV.

[0047] Furthermore, in order to examine the effect of the ratio of Ru and Mn elements in C@RuMn / CNFs on the hydrogen evolution performance of C@RuMn / CNFs, we compared the performance of RuMn / CNFs prepared with different Ru:Mn ratios. Based on the C@RuMn / CNFs samples prepared in Examples 1-3, additional samples with Ru:Mn ratios of 1:2 and 1:4 were prepared; Figure 5 As shown, when the Ru:Mn ratio is 1:1, 1:2, 1:3, 1:4 and 1:5, the driving current is 100mA / cm 2 The overpotentials required for the current density are 141, 94, 80, 122, and >125 mV, respectively. Therefore, at a ratio of 1:3, C@RuMn / CNFs has the best hydrogen evolution catalytic performance.

[0048] The test conditions of the stability test were consistent with those of the hydrogen evolution performance test. The potential changes on the C@RuMn / CNFs or Pt / C electrodes were recorded at a constant current density, such as Figure 6As shown in the figure, the catalytic stability of the Pt / C electrode dropped sharply within 2 hours, with a potential change of up to 330 mV. However, the potential change of C@RuMn / CNFs was only 100 mV after 100 hours of continuous operation. This shows that compared with the Pt / C electrode, C@RuMn / CNFs has better catalytic activity and stability.

[0049] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a ruthenium-manganese alloy catalyst material, characterized in that: The following steps are included: S1. adding ruthenium chloride, manganese acetate and cetyltrimethylammonium bromide to a 10-12% polyacrylonitrile solution (solvent is N,N-dimethylformamide), wherein the mass ratio of cetyltrimethylammonium bromide to polyacrylonitrile is 1:8, the mass ratio of ruthenium chloride to polyacrylonitrile is 1:15, and the mass ratio of manganese acetate to ruthenium chloride is 1-5:1; S2. Stir the above solution for at least 3 hours until the solution is uniform; S3. Pour the prepared solution into a syringe and perform electrospinning in an electrospinning machine at a voltage of 15-20 kV to obtain a RuMn / PAN precursor fiber membrane; S4. The prepared RuMn / PAN precursor fiber membrane is pre-oxidized in a tube furnace, the temperature is raised to 200-300°C, and kept warm for at least 1h; S5. Raise the temperature to 800-1100°C at a rate of 5°C / min and keep it warm for at least 1h under inert gas conditions. After cooling to room temperature, C@RuMn / CNFs are obtained.

2. The method for preparing the ruthenium-manganese alloy catalyst material according to claim 1, characterized in that: The voltage of the electrospinning machine in step S3 is 18 kV.

3. The method for preparing the ruthenium-manganese alloy catalyst material according to claim 1, characterized in that: The temperature of the tube furnace in step S4 is 230°C.

4. The method for preparing the ruthenium-manganese alloy catalyst material according to claim 1, characterized in that: The inert gas in step S5 is argon or nitrogen.

5. A ruthenium-manganese alloy catalytic material, characterized in that: Prepared according to the method of claim 1.

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