Ru-based water electrolysis catalyst composite material, and preparation method and application thereof

Abstract

The application belongs to the technical field of water electrolysis catalysts, and relates to a Ru-based water electrolysis catalyst composite material and a preparation method and application thereof. The composite material takes ZIF-8 derived iron and nitrogen atom doped FeNC nanoparticles as an active carrier, loads sub-nano RuFe alloy particles and Fe elemental nanoparticles, and forms a three-active-site uniformly dispersed multi-level composite structure. Through twice dispersion and calcination, the Fe precursor is dispersed in the ZIF-8 skeleton in situ, the Fe atom and the elemental Fe are uniformly dispersed to construct the Fe / FeNC matrix through the first carbonization, the Ru precursor is adsorbed in the pores of the Fe / FeNC matrix, and the RuFe alloy is constructed and dispersed through the second carbonization, and finally the RuFe / Fe / FeNC composite material is obtained. The composite material provided by the application has high efficient hydrogen evolution and oxygen evolution performance, and has full water splitting industrial application potential in a laboratory electrolytic cell and a commercial PEM electrolytic cell.

Description

Technical Field

[0001] This invention belongs to the field of water electrolysis catalyst technology, specifically relating to a Ru-based water electrolysis catalyst composite material, its preparation method, and its application. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Water electrolysis, as a sustainable hydrogen production method, relies heavily on the performance of catalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Currently, commercial water electrolysis devices mostly use Pt / C as highly efficient HER catalysts, while Ru / Ir-based noble metal catalysts are commonly used for OER catalysis. However, these noble metal catalysts have inherent drawbacks: First, the high cost of noble metals such as Pt and Ir limits their large-scale application; second, while Ru is less expensive in HER, its intrinsic catalytic activity is lower than that of Pt, and the weak bonding between Pt and the carbon support in Pt / C leads to platinum particle aggregation and detachment, affecting stability; third, while Ir exhibits excellent stability in OER, it is expensive, and although Ru's activity is comparable to Ir and its cost is lower, it suffers from insufficient stability. Therefore, developing electrocatalysts that combine high activity, high stability, and low cost has become a key research focus in the field of water electrolysis. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a Ru-based water electrolysis catalyst composite material, its preparation method, and its application.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing a Ru-based water electrolysis catalyst composite material, comprising the following steps:

[0007] Prepare a mixed solution A of zinc acetate and ferric acetylacetone;

[0008] Prepare a mixed solution B of 2-methylimidazole and CTAB;

[0009] Mixed solution A and mixed solution B were mixed under stirring, and the reaction was carried out by stirring for 1-3 hours. After the reaction was completed, Fe-doped ZIF-8 precursor was obtained.

[0010] After washing and drying the obtained Fe-doped ZIF-8 precursor, it was calcined for the first time in an inert atmosphere to obtain Fe nanoparticles and Fe-doped Fe / FeNC intermediates.

[0011] The Fe / FeNC intermediate was added to water, ultrasonically dispersed, and Ru was added.3+ Salt is stirred for a set time, then filtered, washed, and dried, and then calcined a second time in an inert atmosphere to obtain the final product.

[0012] Secondly, the present invention provides a Ru-based water electrolysis catalyst composite material, which is prepared by the aforementioned preparation method.

[0013] Thirdly, the present invention provides the application of the Ru-based water electrolysis catalyst composite material in catalytic water electrolysis.

[0014] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:

[0015] The water electrolysis catalyst composite material of the present invention uses iron and nitrogen atom doped FeNC nanoparticles (particle size of 100-200 nm) derived from ZIF-8 as active carriers, and loads sub-nanometer RuFe alloy particles (particle size of 1-10 nm) and Fe elemental nanoparticles (particle size of 1-10 nm) to form a multi-level composite structure with uniformly dispersed three active sites.

[0016] This invention involves two dispersion and calcination processes. First, the Fe precursor is dispersed in situ in the ZIF-8 framework, and the Fe / FeNC matrix with uniform dispersion of Fe atoms and elemental substances is constructed by the first carbonization. Then, the Ru precursor is adsorbed into the pores of the Fe / FeNC matrix, and the RuFe alloy is constructed and dispersed by the second carbonization, finally obtaining the RuFe / Fe / FeNC composite material.

[0017] This ZIF-derived porous carbon material effectively improves the mass transfer efficiency in the catalytic process; at the same time, the electronic interaction between the Ru active site and the Fe auxiliary site significantly enhances the catalytic activity and stability of Ru.

[0018] This composite material, as a HER / OER bifunctional catalyst, exhibits superior performance compared to commercial Pt / C (cathode)||RuO2 (anode) combined catalysts in laboratory low-current alkaline water electrolysis systems. As a HER catalyst, its performance also surpasses that of Pt / C (cathode)||IrO2 (anode) combined catalysts in industrial high-current proton exchange membrane (PEM) water electrolysis systems, providing a new strategy for reducing the cost of water electrolysis. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0020] Figure 1The images shown are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of RuFe / Fe / FeNC-3 prepared in Example 3 of this invention. Among them, (a) is the SEM image, (b) is the TEM image, (c) is the selected area electron diffraction pattern, (d) is the crystal structure diagram, (e) is the fast Fourier transform diagram of RuFe(100), (f) is the fast Fourier transform diagram of Fe(111) lattice, and (g) is the high-angle annular dark-field elemental mapping diagram.

[0021] Figure 2 In the figure, (a) is the X-ray diffraction pattern of the composite materials prepared in Examples 1 to 5 of the present invention; (b) is the X-ray diffraction pattern of the composite materials of Example 3 and Comparative Examples 1, 2 and 4.

[0022] Figure 3 The above are X-ray diffraction XPS data of Example 3 and Comparative Example 1 of the present invention, wherein (a) is the full spectrum, (b) is the N1s spectrum, (c) is the Fe 2p spectrum, and (d) is the Ru 3p spectrum.

[0023] Figure 4 In the figure, (a) shows the OER linear sweep voltammetry (LSV) polarization curves of Examples 1-5, (b) shows the OER linear sweep voltammetry (LSV) polarization curves of Example 3, Comparative Examples 1-3 and commercial RuO2, and (c) shows the comparison of OER cycle stability results of Example 3 and commercial RuO2.

[0024] Figure 5 In the figure, (a) shows the HER linear sweep voltammetry (LSV) polarization curves of Examples 1-5, (b) shows the HER linear sweep voltammetry (LSV) polarization curves of Examples 3, Comparative Examples 1-3, and Commercial Pt / C, and (c) shows a comparison of the HER cycle stability results of Examples 3 and Commercial Pt / C.

[0025] Figure 6 The comparison diagram (a) shows the laboratory-scale total water splitting performance of Example 3 of the present invention and the commercial combination Pt / C‖RuO2 in alkaline KOH electrolyte, and the performance at 10 mA·cm⁻¹. -2 Figure (b) shows the current density stability test results.

[0026] Figure 7 In the figure, (a) shows the HER polarization curves of Example 3 and the commercial combination Pt / C‖IrO2 in acidic H2SO4 electrolyte, (b) shows the voltage curve of the PEM electrolyzer, and (c) shows the results of the constant current stability test. Detailed Implementation

[0027] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0028] In a first aspect, the present invention provides a method for preparing a Ru-based water electrolysis catalyst composite material, comprising the following steps:

[0029] Prepare a mixed solution A of zinc acetate and ferric acetylacetone;

[0030] Prepare a mixed solution B of 2-methylimidazole and CTAB;

[0031] Mixed solution A and mixed solution B were mixed under stirring, and the reaction was carried out by stirring for 1-3 hours. After the reaction was completed, Fe-doped ZIF-8 precursor was obtained.

[0032] After washing and drying the obtained solid, it was calcined for the first time in an inert atmosphere to obtain Fe nanoparticles and Fe-doped Fe / FeNC intermediates.

[0033] The Fe / FeNC intermediate was added to water, ultrasonically dispersed, and Ru was added. 3+ Salt is stirred for a set time, then filtered, washed, and dried, and then calcined a second time in an inert atmosphere to obtain the final product.

[0034] A stepwise calcination combined with solution adsorption method can achieve uniform dispersion of Ru particles on a Fe / FeNC matrix. The first solution synthesis promotes Fe dispersion in ZIF-8, while the first calcination promotes the formation of Fe nanoparticles. 3+ The addition of Ru to the second solution allows for uniform diffusion of Ru within the Fe / FeNC matrix. The second calcination then allows Ru to fuse with the Fe nanoparticles in the Fe / FeNC matrix, forming a RuFe alloy. This secondary high-temperature treatment strengthens the electronic interactions between Ru and Fe, prevents individual Ru and Fe nucleation, promotes alloy formation, and optimizes the structure of the catalytic active sites.

[0035] ZIF-8 is a metal-organic framework material composed of zinc ions and 2-methylimidazole linkages, serving as a carrier and template for subsequent processes. High-temperature inert atmosphere treatment transforms the ZIF-8 precursor into nitrogen-doped porous carbon (NC) material, where the metal elements are reduced to nanoparticles. Other metals are then added to the NC, uniformly dispersing them within the pores. Further calcination under an inert atmosphere reduces the added metal elements to nanoparticles or forms alloys with the previously added metal particles, resulting in a uniform distribution within the carbon matrix.

[0036] ZIF-8 has a regular microporous structure. During the subsequent calcination process, the zinc metal volatilizes (which has a low boiling point), leaving abundant pores, which effectively increases the specific surface area of ​​the material, provides channels for the transport of reactants and products, and exposes more active sites.

[0037] Adding iron acetylacetone during the synthesis of ZIF-8 allows iron ions to partially replace zinc ions in the framework, achieving atomic-level Fe doping. Iron acetylacetone exhibits good solubility in organic solvents, and its decomposition and reaction rates match those of zinc acetate and 2-methylimidazole, which is beneficial for forming a uniformly doped precursor. Using water-soluble iron salts (such as ferric sulfate) may result in excessively rapid reaction, leading to phase separation or precipitation and hindering uniform doping.

[0038] Fe acts as an auxiliary site, and through its electronic interaction with Ru, it modulates the electronic structure of Ru metal, making its adsorption energy for reaction intermediates closer to the optimal value, thereby significantly improving the catalytic activity and stability of Ru.

[0039] CTAB is a cationic surfactant that adsorbs onto specific crystal faces during the synthesis of ZIF-8, altering the growth rate of different crystal faces and thus controlling the size and morphology of the final product. Without CTAB, ZIF-8 tends to form large, non-uniform rhombic dodecahedrons. Adding CTAB results in smaller, more uniform particles. By controlling the formation of smaller, more uniform particles, CTAB indirectly increases the specific surface area of ​​the material, thereby improving its catalytic performance. Furthermore, CTAB can, to some extent, prevent the aggregation of nanoparticles during synthesis, effectively improving the uniform distribution of active sites, which in turn contributes to enhanced catalytic activity and catalyst stability.

[0040] In this invention, a mixed solution A of zinc acetate and ferric acetylacetone and a mixed solution B of 2-methylimidazole and CTAB are prepared separately. The two solutions are then mixed and reacted. In solution A, zinc acetate and ferric acetylacetone are already uniformly mixed at the molecular level. When mixed with solution B, zinc and iron ions compete to coordinate with 2-methylimidazole. This competitive coordination occurs instantaneously during solution mixing, allowing iron atoms to randomly and uniformly replace some zinc atoms in the ZIF-8 framework at the atomic level, forming a true doped solid solution. If zinc salt and 2-methylimidazole are mixed first, the ZIF-8 framework may have already been initially formed. Adding iron salt after this initial mixing makes it difficult for iron ions to penetrate the already formed crystal; they can only adhere to the surface or form a separate phase, resulting in uneven doping and failing to achieve the desired electronic synergistic effect.

[0041] CTAB is already uniformly dispersed in solution B. At the moment of mixing, CTAB molecules can immediately and uniformly adsorb onto all specific crystal faces of the newly formed ZIF-8 crystal nuclei. This uniform adsorption effectively regulates the growth rate of different crystal faces, thereby precisely controlling the morphology and size of the final product. If CTAB is added later, it cannot effectively interfere with the already started crystal growth process, and its morphology control effect will be weakened.

[0042] In some embodiments, the stirring rate when mixing solution A and solution B is 200-500 r / min.

[0043] Preferably, the stirring rate when mixing solution A and solution B is 200-400 r / min, and more preferably 250-350 r / min.

[0044] When solutions A and B are mixed, a vigorous chemical reaction occurs between them (zinc / iron ions coordinate with 2-methylimidazole), instantly generating a large number of crystal nuclei. The core function of stirring is to accelerate the interdiffusion between solutions A and B, allowing the entire reaction system to reach a molecular-level homogeneous state in the shortest possible time.

[0045] When the stirring rate is too slow, solutions A and B cannot be dispersed quickly and evenly, resulting in areas with high concentrations in certain regions. This has an adverse effect on particle size uniformity, particle morphology, and the uniformity of iron doping.

[0046] In some embodiments, mixed solution A and mixed solution B are mixed and stirred continuously for 1.5-2.5 hours.

[0047] In some embodiments, the Ru 3+ The salts are RuCl3, Ru2(SO4)3, or Ru(NO3)3.

[0048] In some embodiments, the Fe / FeNC intermediate and Ru 3+ The mass ratio of salt is 2~20:1.

[0049] In some embodiments, the molar ratio of zinc acetate, ferric acetylacetone, 2-methylimidazole and CTAB is 120:1~100:400~1500:0.1~0.5.

[0050] In some embodiments, the first calcination conditions are as follows: under an inert atmosphere, the temperature is increased to 800-1000℃ at a rate of 5-10℃ / min, and held for 2-4 h to obtain an Fe / FeNC intermediate after carbonization.

[0051] Preferably, the temperature of the first calcination is 850~950 °C, and the calcination time is 2.5~3.5h.

[0052] In some embodiments, Ru is added 3+ After salting, the Ru in the system 3+ The salt concentration is 0.01~0.1 mol·L⁻¹ -1 .

[0053] Preferably, Ru is added. 3+ After salting, stir for 1-3 hours.

[0054] In some embodiments, the conditions for the second calcination are: 2~5℃·min -1 Heat to 300~600℃ and keep warm for 1~2 hours.

[0055] Preferably, the temperature of the second calcination is 450-550℃, and the calcination time is 1.5-2.5h.

[0056] Further preferably, the temperature of the second calcination is 470-520℃, and the calcination time is 1.7-2.2h.

[0057] Secondly, the present invention provides a Ru-based water electrolysis catalyst composite material, which is prepared by the aforementioned preparation method.

[0058] Thirdly, the present invention provides the application of the Ru-based water electrolysis catalyst composite material in catalytic water electrolysis.

[0059] The present invention will be further described below with reference to the embodiments.

[0060] Example 1

[0061] The preparation method of RuFe / Fe / FeNC-1 includes the following steps:

[0062] Step 1: Preparation of Fe-doped ZIF-8 precursor: Dissolve 430 mg zinc acetate (2.4 mmol) and 692 mg ferric acetylacetone (2.0 mmol) in 10 mL of deionized water and stir magnetically for 5 minutes until completely dissolved to obtain solution A;

[0063] Meanwhile, 2.2 g of 2-methylimidazole (27 mmol) and 2 mg of cetyltrimethylammonium bromide (CTAB) (0.0055 mmol) were dissolved in 10 mL of deionized water and stirred for 10 minutes until clear and transparent to obtain solution B;

[0064] Under magnetic stirring at 300 r / min, solution B was quickly poured into solution A, and stirring was continued for 2 hours to form a milky white precipitate;

[0065] After the reaction was completed, the precipitate was collected by centrifugation at 8000 r / min for 10 minutes, washed three times with deionized water, and dried overnight in a vacuum drying oven at 60℃ to obtain the Fe-doped ZIF-8 precursor. Then, it was calcined at 900℃ for 2 h in a nitrogen atmosphere to obtain the carbonized intermediate, named Fe / FeNC.

[0066] Step 2: Weigh 50 mg of Fe / FeNC matrix, add 20 mL of deionized water and sonicate for 1 hour, add 5 mg of RuCl3 and stir for 2 hours, then filter, wash and dry, and calcine at 500 °C for 2 hours in a nitrogen atmosphere to finally obtain the black sample RuFe / Fe / FeNC-1.

[0067] Example 2

[0068] The preparation method of RuFe / Fe / FeNC-2 differs from that in Example 1 in that the mass of iron acetylacetone added is 140 mg (0.4 mmol).

[0069] Example 3

[0070] The preparation method of RuFe / Fe / FeNC-3 differs from that in Example 1 in that the mass of iron acetylacetone added is 66 mg (0.2 mmol).

[0071] Example 4

[0072] The preparation method of RuFe / Fe / FeNC-4 differs from that in Example 1 in that the mass of iron acetylacetone added is 14 mg (0.04 mmol).

[0073] Example 5

[0074] The preparation method of RuFe / Fe / FeNC-5 differs from that in Example 1 in that the mass of iron acetylacetone added is 6.9 mg (0.02 mmol).

[0075] Comparative Example 1

[0076] The preparation method of Ru / NC differs from that in Example 3 in that iron acetylacetone is not added.

[0077] Comparative Example 2

[0078] The preparation method of Fe / FeNC differs from that in Example 3 in that it only has a first step and no second step.

[0079] Comparative Example 3

[0080] The preparation method of NC differs from that of Example 3 in that there is only a first step and no second step, and acetylacetone iron is not added in the first step.

[0081] Comparative Example 4

[0082] The method for preparing FeNC differs from that in Example 5 in that it only has a first step and no second step.

[0083] Results and Discussion:

[0084] SEM image of RuFe / Fe / FeNC-3 prepared in Example 3 is shown below. Figure 1 As shown in Figure a, after two high-temperature calcination treatments, the material exhibits a uniformly dispersed nanoparticle morphology with a particle size of 100-200 nm and no obvious agglomeration. This morphological feature can increase the specific surface area of ​​the material, providing sufficient exposure space for active sites in OER and HER reactions, which is beneficial to improving the contact efficiency of catalytic reactions.

[0085] Figure 1 Figure b shows the HRTEM image of RuFe / Fe / FeNC-3. The image clearly shows that the metal nanoparticles are uniformly dispersed on the carbon matrix without significant aggregation. The particle size is uniform and controlled within the range of 1–10 nm. This uniform dispersion avoids the loss of active sites caused by Ru and Fe particle agglomeration, while simultaneously strengthening the electronic interactions between Ru, Fe, and the Fe / NC matrix. The dual active sites lay the structural foundation for the synergistic enhancement of catalytic performance.

[0086] Figure 1 In the diagram, c represents the selected area electron diffraction pattern of RuFe / Fe / FeNC-3, and correspondingly, Figure 1 In Figures d, e, and f, we see the lattice diagrams of RuFe / Fe / FeNC. Two different lattice sizes are present. The lattice fringe spacing in figure e is measured to be 0.230 nm, which is lower than the standard lattice spacing of the Ru(100) crystal plane (0.234 nm), indicating the possible incorporation of smaller atoms. Figure 1 f is the inverse Fourier transform diagram of the Fe(111) lattice. The lattice fringe spacing was measured to be 0.211 nm, which is consistent with the standard lattice parameters of the Fe(111) crystal plane.

[0087] Figure 1Figure g shows the HADDF diagram of RuFe / Fe / FeNC-3 and the corresponding elemental mapping diagrams of Fe, Ru, and C. The elemental distribution diagrams show that Fe, Ru, and C are uniformly distributed in the material: C acts as the framework component of the FeNC matrix, forming a continuous conductive network; Ru is uniformly distributed in the form of nanoparticles around the C framework and Fe. Detailed comparison reveals that the large bright particles in the HADDF diagram (marked in yellow and red) are not entirely Ru or Fe, but a mixture of Ru and Fe, confirming that they form a RuFe alloy.

[0088] In summary, Fe exists in three forms: some Fe reacts with NC to form FeNC; some Fe is dispersed on FeNC as Fe nanoparticles; and some Fe is incorporated into Ru particles to form RuFe alloy nanoparticles, which are dispersed on FeNC.

[0089] X-ray diffraction (XRD) analysis is used to assess the phase composition of materials. Figure 2 Figure a shows the XRD patterns of Examples 1-5, and figure b shows the XRD patterns of Examples 1, Comparative Example 1, Comparative Example 2, and Comparative Example 4, compared with standard cards for Ru (PDF#06-0663), Fe (PDF#19-0629), and Fe (PDF#52-0513). Comparative analysis shows that the characteristic peak of Ru (PDF#06-0663) appeared in all Examples 1-5, and the characteristic peak of Ru in Example 5 showed a high-angle shift compared to that in Comparative Example 1, confirming that Fe doping and Ru formed a RuFe alloy.

[0090] Furthermore, when the Fe content was low (≤14mg), no obvious characteristic peaks of Fe metal appeared in Examples 4, 5, and Comparative Example 4, confirming that Fe was doped into the C substrate in atomic form and combined with N to form a FeNC substrate. When the Fe content was moderate (66mg), characteristic peaks of trace Fe elemental matter appeared in Examples 3 and Comparative Example 2 (PDF#52-0513), confirming the presence of a small amount of Fe elemental matter. However, when the amount of Fe added was high (≥140mg), additional Fe impurity peaks were formed (PDF#19-0629), indicating that excessive Fe addition would affect the purity of Fe elemental matter. XRD results analysis showed that Examples 1-3 contained three components: FeNC, Fe elemental matter, and RuFe alloy.

[0091] X-ray photoelectron spectroscopy (XPS) was used to test and analyze the surface chemical states and bonding of Example 3 and Comparative Example 1. Figure 3Figure a presents the XPS full spectra of Example 3 (RuFe / Fe / FeNC-3) and Comparative Example 1 (Ru / NC), showing that RuFe / Fe / FeNC-3 contains five elements: C, N, O, Ru, and Fe, while Ru / NC contains only four elements: C, N, O, and Ru. This is completely consistent with the previous structural analysis results of the materials. High-resolution spectra of the N 1s element (…) Figure 3 Analysis in section b) revealed that the N 1s phase of RuFe / Fe / FeNC-3 can be retrosynthesized to form TM-N bonds, confirming that some Fe exists in the form of Fe-N bonds. The Fe 2p peak (…) Figure 3 c) shows Fe 0 Price and Fe 2+ / Fe 2+ The peaks of Ru 3p are attributed to the metallic state and Fe-N bonds, as well as the oxidation state of some surfaces. Figure 3 In section d), most Ru exists in a zero-valent form, corresponding to Ru metal, and shows a positive shift of 0.8 eV relative to Ru / NC, which can be attributed to the formation of RuFe alloy. XPS results further validate the previous SEM and XRD results: the compositions in Examples 1-3 include RuFe alloy, elemental Fe, and FeNC substrate.

[0092] Regarding catalytic performance, the OER and HER electrochemical behavior of the samples from Examples 1-5 and Comparative Examples 1-3 in 1 M KOH were systematically evaluated.

[0093] The electrode preparation process is as follows: 2 mg of catalyst and 2 mg of acetylene black are mixed and ultrasonically dispersed in a mixture of 20 μL Nafion solution, 380 μL ethanol and 100 μL deionized water for 30 minutes to form a uniform catalyst ink.

[0094] Ink was dropped onto the surface of the glassy carbon electrode, and the catalyst loading was controlled at 0.32 mg·cm⁻¹. -2 After drying, it is used as the working electrode, while a graphite rod is used as the counter electrode and Ag / AgCl is used as the reference electrode to construct a three-electrode testing system.

[0095] The catalytic performance of OER and HER was systematically evaluated in 1 M KOH electrolyte.

[0096] Basic OER polarization curve ( Figure 4 As shown in a), the OER performance of Examples 1-5 first improved and then deteriorated with increasing Fe content, reaching its optimal performance in Example 3 (RuFe / Fe / FeNC-3) at 10 mA·cm⁻¹. -The overpotential at the given current density was 282 mV, indicating that Fe plays a significant role in regulating the catalyst's performance. Furthermore, Figure 4 As shown in Figure b, the OER performance of Example 3 (RuFe / Fe / FeNC-3) was also significantly better than that of comparative samples 1-3, confirming that both the RuFe alloy and elemental Fe play important roles in improving HER performance. Stability test ( Figure 4 As shown in c), after 5000 cycles, the overpotential of Example 3 (RuFe / Fe / FeNC-3) decreased by only 6 mV. This excellent stability is attributed to the electronic interaction between the RuFe alloy, elemental Fe, and the FeNC matrix. The RuFe alloy is the main OER active site, while elemental Fe and FeNC sites assist the OER reaction steps, forming a synergistic catalytic mechanism.

[0097] alkaline HER performance such as Figure 5 As shown in Figure a, with the increase of Fe content, the HER performance of Examples 1 to 5 first improved and then deteriorated, reaching the optimal performance in Example 3 (RuFe / Fe / FeNC-3). Figure 5 As shown in Figure b, Example 3 (RuFe / Fe / FeNC-3) at 10 mA·cm -2 The overpotential was as low as 18 mV, significantly lower than that of Ru / NC (170 mV), Fe / NC (348 mV), and NC (386 mV). HER stability testing ( Figure 5 In c), the overpotential decay after 5000 cycles was only 7 mV, which is attributed to the strong interfacial bonding between the RuFe alloy and elemental Fe, as well as the porous structure of the FeNC matrix, which effectively suppressed particle agglomeration and shedding.

[0098] To further verify its practical application potential, Example 3 (RuFe / Fe / FeNC-3) was used as a bifunctional catalyst to construct a laboratory-scale alkaline water electrolysis device. The RuFe / Fe / FeNC-3 catalyst was modified onto the surfaces of two glassy carbon electrodes (preparation process as described in HER and OER tests), constructing a water electrolysis device that simultaneously uses RuFe / Fe / FeNC-3 as both the cathode (catalyzing HER) and anode (catalyzing OER). The control sample was a commercially available combination of Pt / C (catalyzing HER) || RuO2 (catalyzing OER), with all other preparation processes identical.

[0099] The test results show that ( Figure 6 (a) The device operates at 20 mA·cm⁻¹ -2 The cell voltage was 1.52 V, significantly lower than that of commercially available Pt / C||RuO2 catalyzed water electrolysis devices (1.75 V). Constant voltage stability test ( Figure 6In (b), the current density decay rate after 60 h is only 5.5%, highlighting its robustness.

[0100] To demonstrate its practical applicability, acidic HER performance was tested using an industrial PEM electrolyzer. Acidic HER performance was assessed in 0.5 M H₂SO₄ electrolyte, while other tests were conducted consistent with those for alkaline electrochemical performance.

[0101] The industrial PEM electrolyzer preparation process is as follows: When preparing the catalyst slurry, the cathode catalyst is first pre-wetted with ultrapure water, and then an alcohol solvent is added and ultrasonically dispersed in an ice-water bath for 120 minutes to form a primary suspension.

[0102] Subsequently, a Nafion ionomer solution was added, and ball milling was performed to enhance binding. Using a high-precision peristaltic pump system with pulsation-suppressed continuous liquid supply, the slurry was sprayed onto the pretreated Nafion 115 proton exchange membrane (500 cm⁻¹) at a rate of 1 mL / min. 2 On the other side, IrO2 is sprayed as the anode.

[0103] After the membrane electrode and the diffusion layer are stacked, they are subjected to high temperature and high pressure in a hot press, and the pressure is released and maintained for cooling in stages, so that the catalyst layer is embedded in the proton membrane to form a continuous proton channel and reduce the interfacial resistance.

[0104] Finally, the membrane electrode assembly and bipolar plates are assembled to form a PEM electrolyzer.

[0105] This preparation and testing method ensures the controllability of the catalyst's structure and the reliability of its electrochemical performance, providing a theoretical basis and practical foundation for industrial applications.

[0106] In acidic environments, the HER performance of RuFe / Fe / FeNC-3 ( Figure 7 a) at 10 mA·cm -2 The overpotential is 13 mV, comparable to that of Pt / C. It was used as the cathode catalyst in a PEM electrolyzer (with IrO2 as the anode) under high current conditions (1.5 A·cm⁻¹). -2 The slot voltage is 1.79 V. Figure 7 (b), lower than Pt / C||IrO2 devices (1.88 V). After constant current testing for 4000 h ( Figure 7 (c) The current density decay rate is as low as 2.5 μV / h, confirming its long-term stability in a high-current PEM electrolyzer.

[0107] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of making a Ru-based water electrolysis catalyst composite material, characterized by: The method comprises the following steps: Preparation of mixed solution A of zinc acetate and iron acetylacetone; Preparation of mixed solution B of 2-methylimidazole and CTAB; Mixing mixed solution A and mixed solution B under stirring, and continuing stirring for 1-3 h to react, and obtaining Fe-doped ZIF-8 precursor after the reaction, wherein the molar ratio of zinc acetate, iron acetylacetone, 2-methylimidazole and CTAB is 120:10-100:400-1500:0.1-0.5; Washing and drying the obtained Fe-doped ZIF-8 precursor, and performing first calcination in an inert atmosphere to obtain Fe nanoparticles and Fe-doped Fe / FeNC intermediate; The Fe / FeNC intermediate was added to water, ultrasonically dispersed, and Ru was added 3+ The salt was stirred for the set time, then filtered, washed, dried, and subjected to a second calcination in an inert atmosphere.

2. The preparation method of the Ru-based water electrolysis catalyst composite material according to claim 1, characterized in that: The stirring speed during mixing mixed solution A and mixed solution B is 200-500 r / min.

3. The preparation method of the Ru-based water electrolysis catalyst composite material according to claim 2, characterized in that: The time for continuing stirring after mixing mixed solution A and mixed solution B is 1.5-2.5 h.

4. The method of claim 1, wherein: The Ru 3 + The salt is RuCl3, Ru2(SO4)3or Ru(NO3)3.

5. The method of claim 1, wherein: Fe-doped ZIF-8 precursors and Ru 3+ The mass ratio of the salt is 2-20:

1.

6. The method of claim 1, wherein: The first calcination condition is: heating to 800-1000 ℃ at 5-10 ℃ / min under an inert atmosphere, and keeping the temperature for 2-4 h, and obtaining Fe / FeNC intermediate after carbonization.

7. The method for preparing the Ru-based water electrolysis catalyst composite material according to claim 1, characterized in that: The second calcination condition is: heating to 300-600 ℃ at 2-5 ℃ / min, and keeping the temperature for 1-2 h.

8. The method for preparing the Ru-based water electrolysis catalyst composite material according to claim 7, characterized in that: The second calcination temperature is 450-550 ℃, and the calcination time is 1.5-2.5 h.

9. A Ru-based water electrolysis catalyst composite material, characterized by: Prepared by the preparation method in any one of claims 1-8.

10. Application of the Ru-based water electrolysis catalyst composite material in claim 9 in catalyzing water electrolysis.

Images