Preparation method and application of MnO-Ru / NFs catalyst
The preparation of MnO-Ru/NFs catalysts by electrospinning and high-temperature carbonization solves the problems of scarcity and high cost of traditional precious metal catalysts, realizes efficient and stable hydrogen production by water electrolysis, reduces production costs and improves catalytic activity.
Patent Information
- Application Number
- CN202510120555.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-25
- Publication Date
- 2025-11-11
- Estimated Expiration
- 2045-01-25
AI Technical Summary
The scarcity and high cost of precious metal catalysts in traditional water electrolysis hydrogen production technology limit its large-scale commercial application, and existing alternative materials are insufficient in terms of catalytic activity and stability.
MnO-Ru/NFs catalysts were prepared by electrospinning and high-temperature carbonization. By loading manganese and ruthenium onto carbon nanofibers, highly dispersed MnO-Ru nanoparticles were formed. The electronic structure of Ru was adjusted to optimize the adsorption energy of reaction intermediates, combined with the high specific surface area and electrical conductivity of carbon nanofibers.
The MnO-Ru/NFs catalyst significantly improves the activity and stability of the water electrolysis reaction and reduces the cost of the catalyst. Under alkaline conditions, the MnO-Ru/NFs catalyst exhibits excellent HER and OER catalytic performance, can operate stably at high current densities, and is inexpensive, making it suitable for large-scale production.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of water electrolysis catalysts; more specifically, it relates to a method for preparing a MnO-Ru / NFs catalyst and its application in the electrocatalytic water splitting reaction. Background Technology
[0002] Hydrogen energy, as a clean energy carrier, is primarily produced through the electrolysis of water. With the global energy structure transformation and the increasing demand for renewable energy, efficient and economical water electrolysis technology is becoming increasingly important. Traditional water electrolysis hydrogen production technologies mostly use precious metals such as platinum (Pt), ruthenium (Ru), and iridium (Ir) as electrocatalysts; however, the scarcity and high cost of these precious metals severely limit their widespread adoption in large-scale commercial applications.
[0003] To overcome these limitations, the search for more economical and sustainable alternative materials is imperative. Transition metal-based catalysts have become a research hotspot in this field due to their abundant reserves and low cost, especially manganese (Mn), which is not only inexpensive but also exhibits good catalytic activity. Furthermore, in terms of catalyst support selection, carbon nanofibers (CNFs) have become ideal support materials due to their high specific surface area, good electrical conductivity, and chemical stability. Loading active metal particles onto CNFs facilitates the exposure of catalytic active sites and rapid electron transfer, thereby improving the activity and stability of the catalyst. Summary of the Invention
[0004] To further develop the existing technology, the first aspect of the present invention provides a method for preparing a MnO-Ru / NFs catalyst, comprising the following steps:
[0005] Organic carbon source, manganese source and ruthenium source are dissolved in a mixed solvent of DMF and ethanol to obtain a precursor solution;
[0006] The precursor solution was electrospinned to prepare precursor nanofibers;
[0007] The precursor nanofibers are first pre-oxidized in an air atmosphere, and then carbonized and calcined in an inert atmosphere to obtain the MnO-Ru / NFs catalyst.
[0008] Furthermore, the pre-oxidation temperature is 150–300°C, and the time is 1–3 hours.
[0009] Furthermore, the carbonization and roasting temperature is 600–800°C, and the time is 2–5 hours.
[0010] Furthermore, the organic carbon source is PVP.
[0011] Furthermore, the manganese source is manganese acetylacetone, and the ruthenium source is ruthenium chloride.
[0012] Furthermore, the molar ratio of the manganese source to the ruthenium source is 5 to 15:1.
[0013] Furthermore, the volume ratio of DMF to ethanol in the mixed solvent is 1:1.
[0014] The second aspect of the present invention discloses the application of the MnO-Ru / NFs catalyst obtained by the aforementioned preparation method in the electrocatalytic water splitting reaction under alkaline conditions.
[0015] The technical solution of the present invention has the following beneficial effects:
[0016] 1. This invention obtains a MnO-Ru / NFs catalyst through electrospinning and calcination carbonization, wherein MnO and Ru are highly dispersed on a carbon nanofiber support, and some Ru is incorporated into the MnO lattice, enabling MnO to more effectively regulate the electronic structure of Ru and optimize the adsorption energy of reaction intermediates, thereby improving the catalyst's activity for water electrolysis reaction, which helps to increase the hydrogen generation rate and overall energy efficiency.
[0017] 2. In this invention, after a high-temperature carbonization and calcination step, Ru and MnO nanoparticles maintain high dispersion while interacting strongly with the carbon nanofiber support, resulting in excellent structural stability of the catalyst.
[0018] 3. The MnO-Ru / NFs catalyst prepared in this invention exhibits excellent HER (hydrogen evolution reaction) and OER (oxygen evolution reaction) catalytic performance under alkaline conditions, and at 100 mA cm⁻¹ -2 It can operate stably for at least 250 hours at current density. When used as a bifunctional catalyst for overall water splitting, the electrolyzer operates at 500 mA cm⁻¹. -2 It requires only a 1.88V tank voltage at industrial-grade current density.
[0019] 4. By using lower-cost manganese and a relatively small amount of ruthenium instead of traditional precious metals such as platinum or iridium, this invention significantly reduces the total cost of the catalyst, making large-scale production and application of the catalyst economically feasible.
[0020] To more clearly illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description
[0021] Figure 1 These are the XRD patterns of the catalysts in the examples and comparative examples;
[0022] Figure 2In the figures: a is the Ru 3p XPS spectrum of the MnO-Ru / NFs catalyst of Example 1 and Comparative Example 1 Ru / NFs catalyst; b is the Mn 2p XPS spectrum of the MnO / NFs catalyst of Example 2 and Comparative Example 2 MnO / NFs catalyst; c is the O1s XPS spectrum of the catalyst of Example 1; d is the N1s XPS spectrum of the catalyst of Example 2.
[0023] Figure 3 In the middle: a is a SEM image of the MnO-Ru / NFs catalyst in the example, and b, c and d are its TEM images;
[0024] Figure 4 In the image: a) is a comparison graph of the HER linear sweep voltammetry (LSV) curves of the examples, comparative examples, and commercial Pt / C catalysts; b) is a comparison graph of their Tafel slopes; c) is a comparison graph of their double-layer capacitance (C0). dl (Comparison chart, d is the HER chronovoltage curve (CP) of the MnO-Ru / NFs catalyst in the example;)
[0025] Figure 5 In the image: a) is a comparison graph of the OER linear sweep voltammetry (LSV) curves of the examples, comparative examples, and commercial RuO2 catalysts; b) is a comparison graph of their Tafel slopes; c) is a comparison graph of their double-layer capacitance (C0). dl (Comparison chart, d is the OER chronovoltage curve (CP) of the MnO-Ru / NFs catalyst in the example;)
[0026] Figure 6 In the middle: a is a comparison of the total water splitting LSV of the MnO-Ru / NFs catalyst in the example and the commercial catalyst; b is the Faraday efficiency (FE) of the MnO-Ru / NFs catalyst in the example, which was obtained by testing and calculation through the hydrogen production efficiency testing system.
[0027] Figure 7 This is a chronovoltage curve (CP) of the total water splitting of the MnO-Ru / NFs catalyst in the example. Detailed Implementation
[0028] This invention discloses a method for preparing MnO-Ru / NFs catalysts by combining electrospinning and high-temperature carbonization, comprising the following steps:
[0029] An organic carbon source, such as PVP (polyvinylpyrrolidone), a manganese source, such as manganese acetylacetonate, and a ruthenium source, such as ruthenium chloride, are dissolved in a mixed solvent of DMF (N,N-dimethylformamide) and ethanol in a predetermined ratio to obtain a precursor solution. For example, the degree of polymerization of PVP is ~1,300,000, the volume ratio of DMF to ethanol is 1:1, and the molar ratio of manganese acetylacetonate to ruthenium chloride is 10:1.
[0030] Precursor nanofibers were prepared by electrospinning the precursor solution.
[0031] The precursor nanofibers were first pre-oxidized in an air atmosphere, and then carbonized and calcined in an inert atmosphere to obtain the MnO-Ru / NFs catalyst.
[0032] The pre-oxidation temperature can be 150–300℃ (e.g., 200℃) and the time can be 1–3h (e.g., 2h); the carbonization roasting temperature can be 600–800℃ (e.g., 700℃) and the time can be 2–5h (e.g., 2h).
[0033] The present invention will now be described in more detail with reference to specific embodiments and comparative examples.
[0034] Example: Preparation of MnO-Ru / NFs catalyst
[0035] (1) Dissolve 0.5g PVP in a mixed solvent of 3mL DMF and 3mL ethanol, and stir magnetically for 12h to obtain a transparent solution.
[0036] (2) Dissolve 0.5 mmol manganese acetylacetone and 0.05 mmol ruthenium chloride in the above transparent solution to obtain the precursor solution.
[0037] (3) The precursor solution was used to prepare precursor nanofibers by electrospinning. The electrospinning voltage was 17 kV, and the syringe injection speed was 0.8 mL / h. -1 The syringe needle is size 21, and the distance between the syringe and the receiver is 16cm.
[0038] (4) The precursor nanofibers were pre-oxidized in air at 200°C for 2 hours; then, the temperature was raised to 700°C in nitrogen atmosphere and calcined for 2 hours to obtain the MnO-Ru / NFs catalyst.
[0039] Comparative Example 1: Preparation of Ru / NFs catalyst
[0040] The difference between Comparative Example 1 and the Example is that in step (2), only 0.05 mmol of ruthenium chloride was added to the transparent solution.
[0041] Comparative Example 2: Preparation of MnO / NFs catalyst
[0042] The difference between Comparative Example 2 and the Example is that in step (2), only 0.5 mmol of manganese acetylacetone was added to the transparent solution.
[0043] Morphology and phase analysis of the examples and comparative examples
[0044] Figure 1The X-ray diffraction (XRD) patterns verified the crystal structure and composition of the catalyst prepared in Example 1. Figure 1 As can be seen from a, the XRD pattern of the MnO-Ru / NFs prepared in Example 1 shows no other impurity peaks, indicating that it does not contain any other impurities, and the diffraction peak positions correspond to those on the PDF card of standard MnO. From Figure 1 As can be seen from b, the peak of MnO-Ru / NFs shows a certain degree of negative shift relative to the peak of MnO / NFs, indicating that some Ru has been incorporated into the MnO lattice. No Ru peak was found in the spectrum, possibly due to the low Ru content and its incorporation into the MnO lattice.
[0045] Figure 2 These are the XPS spectra of the catalysts in the examples and comparative examples. Figure 2 a shows the Ru 3p XPS spectra of Examples 1 and Comparative Example 1. Two peaks are observed at 484.0 and 461.8 eV, corresponding to the 3p¹ / ² and 3p³ / ² orbitals of zero-valent Ru. Two other peaks at binding energies of 487.1 and 463.5 eV correspond to Ru... 4+ The 3p1 / 2 and 3p3 / 2 orbitals. Figure 2 b shows the Mn 2p XPS spectra of the catalysts of Example 1 and Comparative Example 2, with the peaks at binding energies of 653.4 and 641.7 eV corresponding to Mn. 2+ The 2p1 / 2 and 2p3 / 2 orbits, with the remaining peak belonging to the satellite peak. From Figure 2 The comparison between a and 2b shows that MnO-Ru / NFs... 2+ Peak relative to MnO / NFs 2+ The peak shifted negatively by approximately 0.41 eV, while Ru 0 The peak shifted positively by about 0.21 eV, indicating that some electrons were transferred from Ru to the Mn site. The decrease in electron density of Ru nanoparticles is conducive to H desorption and promotes the HER and OER reactions.
[0046] Figure 2 c shows the O1s XPS spectrum of the MnO-Ru / NFs catalyst, where the three peaks correspond to the MO bond, the chemisorbed hydroxyl group (-OH), and the carboxyl group (-COO). Figure 2 Figure d shows the N1s XPS spectrum of the MnO-Ru / NFs catalyst, where the peaks correspond to three N configurations: pyridine N (398.5 eV), pyrrole N (399.5 eV), and graphitic N (400.7 eV). The presence of multiple N and O species in MnO-Ru / NFs can create defects on the surface of carbon nanofibers, thereby enhancing their reactivity.
[0047] Figure 3a and b are field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM) images of the MnO-Ru / NFs catalyst in the example, which clearly show that the nanoparticles are very uniformly distributed on the carbon nanofiber morphology. Figure 3 Medium-resolution transmission electron microscopy (HRTEM) images c and d show two different lattice fringes with lattice spacings of 0.255 nm and 0.442 nm, respectively, corresponding to the (111) crystal plane of MnO and the (201) crystal plane of Ru.
[0048] Electrocatalytic performance tests of examples and comparative examples
[0049] The three-electrode system was tested in a 1 mol / L KOH solution saturated with N2; the reference electrode was an Ag / AgCl electrode, and the counter electrode was a Pt sheet electrode.
[0050] The water splitting test was conducted in a 1 mol / L KOH solution saturated with N2; the reference electrode and the counter electrode were both catalysts prepared in Example 1.
[0051] Figure 4 The performance comparison of HER using different catalysts is shown. Figure 4 The HER linear sweep voltammetry (LSV) curves of the MnO-Ru / NFs catalyst at 10 mA cm⁻¹ are shown. -2 The overpotential at a current density is only 16mV, and at 500mA cm⁻¹ -2 At a voltage of 216 mV, it exhibits the lowest overpotential and demonstrates significant activity in HER. For example... Figure 4 As shown in the Tafel slope plot of b, the Tafel slope of MnO-Ru / NFs is 27.5 mV dec. -1 This low value indicates its rapid kinetic characteristics in the HER reaction. Figure 4 c shows the bilayer capacitance (Cdl) that can be used to evaluate and compare the electrochemically active surface area (ECSA), with the Cdl of MnO-Ru / NFs reaching 502.3 mF cm⁻¹. -2 The concentration was significantly higher than that of other comparative samples, indicating that MnO-Ru / NFs can provide more active sites during the reaction process. Figure 4 The chronovoltage curve (CP) of d shows that at 100mA cm -2 At a constant current density, the MnO-Ru / NFs catalyst exhibited stability for more than 50 hours, with almost no decay in HER catalytic activity, demonstrating its excellent durability.
[0052] Figure 5 The electrochemical performance of different catalysts in OER is demonstrated. For example... Figure 5The OER linear sweep voltammetry (LSV) curves of MnO-Ru / NFs catalyst at 10 mA cm⁻¹ are shown in the comparison figure. -2 The overpotential at current density is only 265mV, while at 500mA / cm -2 The overpotential was 396 mV, exhibiting the lowest overpotential among all samples, demonstrating superior OER catalytic activity compared to Ru / NFs, MnO / NFs, and commercial Ru₂O. Figure 5 As shown in the Tafel slope plot of b, the Tafel slope of the MnO-Ru / NFs catalyst is 48.1 mV dec. -1 This minimum value indicates that it has faster reaction kinetics in OER than other test samples. Figure 5 The electrochemically active surface area (ECSA) of each sample was evaluated by measuring the bilayer capacitance (Cdl). The Cdl value of MnO-Ru / NFs was 17.9 mF cm⁻¹. -2 The concentration was higher than that of other control samples, indicating that it can provide more active sites during the OER process. Figure 5 The chronovoltage curve (CP) of d shows that at 100mA cm -2 Long-term stability tests conducted at current density showed that the MnO-Ru / NFs catalyst exhibited almost no degradation in OER catalytic activity after more than 50 hours of continuous operation, demonstrating excellent durability.
[0053] Figure 6 The data in the example show a performance comparison between the MnO-Ru / NFs catalyst and a commercial catalyst in the total hydrolysis reaction. Figure 6 In a, at 10mA cm -2 and 500mAcm -2 In the current density tests, the MnO-Ru / NFs catalyst in the examples only required voltages of 1.53V and 1.84V to achieve these current densities, demonstrating performance far exceeding that of commercial catalysts. The Faraday efficiency (FE) of MnO-Ru / NFs was evaluated using a hydrogen production efficiency testing system, such as... Figure 6 As shown in b, by comparing the theoretical gas production with the measured gas production, the volume ratio of H2 to O2 is found to be 2:1. This result indicates that the Faraday efficiency of MnO-Ru / NFs in the overall water electrolysis process is close to 100%, demonstrating its excellent overall water electrolysis catalytic activity.
[0054] Figure 7 The chronovoltaic curve (CP) of the complete water splitting shows that at 100 mA cm⁻¹ -2At current densities of [value missing], the MnO-Ru / NFs catalyst exhibited continuous operation for over 250 hours with almost no decline in catalytic activity.
[0055] In summary, this invention combines electrospinning technology with a carbonization and calcination step to prepare a MnO-Ru / NFs catalyst. The use of electrospinning technology makes the catalyst production process easy to control and scale up, helping to meet the needs of large-scale industrial production. The tunability of this technology also allows for fine-tuning of the catalyst's performance to adapt to different application requirements. Furthermore, the preparation method of this invention can uniformly load Ru and MnO particles onto carbon nanofibers, significantly improving the efficiency of electrocatalytic water splitting through the synergistic effect of Mn and Ru. In addition, this catalyst exhibits high stability and excellent electrocatalytic performance, providing an effective technical solution to address the problems of high cost and resource constraints of traditional precious metal catalysts.
Claims
1. A method for preparing a MnO-Ru / NFs catalyst, comprising the following steps: Organic carbon source, manganese source and ruthenium source are dissolved in a mixed solvent of DMF and ethanol to obtain a precursor solution; The precursor solution was electrospinned to prepare precursor nanofibers; The precursor nanofibers are first pre-oxidized in an air atmosphere, and then carbonized and calcined in an inert atmosphere to obtain the MnO-Ru / NFs catalyst.
2. The preparation method according to claim 1; wherein, The pre-oxidation temperature is 150–300°C, and the time is 1–3 hours.
3. The preparation method according to claim 1; wherein, The carbonization roasting temperature is 600-800℃, and the time is 2-5 hours.
4. The preparation method according to claim 1; wherein, The organic carbon source is PVP.
5. The preparation method according to claim 1; wherein, The manganese source is manganese acetylacetone, and the ruthenium source is ruthenium chloride.
6. The preparation method according to claim 1; wherein, The molar ratio of the manganese source to the ruthenium source is 5 to 15:
1.
7. The preparation method according to claim 1; wherein, The volume ratio of DMF to ethanol in the mixed solvent is 1:
1.
8. The application of the MnO-Ru / NFs catalyst obtained by any one of claims 1 to 7 in the electrocatalytic water splitting reaction under alkaline conditions.