A self-supporting hydrogen evolution cathode of foam nickel loaded FeCoRu-MOF wrinkled nanoflower and a preparation method and application thereof

Abstract

The application provides a self-supporting hydrogen evolution cathode of FeCoRu-MOF wrinkled nanoflower loaded on nickel foam as well as a preparation method and application thereof. The self-supporting cathode takes nickel foam as a conductive framework, FeCo-MOF nanoflower precursors are first grown in situ on the surface of the nickel foam, then Ru species are introduced through secondary solvothermal treatment of a ruthenium-containing source, FeCo-MOF nanoflowers are further converted into FeCoRu-MOF nanoflower structures assembled by wrinkled nanosheet / petal units, and small-size Ru particles / clusters are formed on the nanoflower petals. In the structure, the nickel foam provides a continuous conductive path and open pores, the electronic interaction between metal centers such as Fe, Co, Ni and Ru is beneficial to adjusting the adsorption / desorption behavior of hydrogen evolution reaction intermediates, and the wrinkled nanoflower structure is beneficial to exposing active sites, promoting electrolyte infiltration and hydrogen bubble release. The application also provides application of the FeCoRu-MOF@NF self-supporting hydrogen evolution cathode in alkaline hydrogen evolution reaction and anion exchange membrane water electrolysis devices.

Description

Technical Field

[0001] This invention belongs to the fields of nanomaterial preparation, electrocatalytic hydrogen evolution, and anion exchange membrane water electrolysis for hydrogen production. Specifically, it relates to a nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode, its preparation method, and its application. Background Technology

[0002] Against the backdrop of global energy structure transformation and increasing demand for carbon emission reduction, green hydrogen energy is considered an important energy carrier connecting renewable energy with fields such as chemical engineering, metallurgy, and energy storage. Electrolysis of water to produce hydrogen has advantages such as a wide range of raw material sources, high product purity, and a clean and controllable process, making it a crucial technological route for achieving large-scale green hydrogen production.

[0003] Anion exchange membrane water electrolysis (AEMWE) combines the characteristics of alkaline water electrolysis and membrane water electrolysis, and has the potential to use non-precious metal or low-precious metal supported catalysts, has a compact system structure, and is suitable for high current density operation. Among them, the activity, conductivity, interfacial stability, and resistance to bubble impact of the cathode hydrogen evolution reaction (HER) catalyst directly affect the cell voltage and long-term operating life of the device.

[0004] Currently, traditional powdered hydrogen evolution catalysts typically require the addition of binders such as Nafion and PVDF, which are then coated onto the surface of the current collector. These electrodes are prone to problems under high current densities, including active sites being obscured by the binder, increased electron transport resistance, and catalyst layer detachment due to bubble erosion, making it difficult to meet the requirements for long-term stable operation at industrial current densities. Nickel foam, with its three-dimensional conductive framework, open channels, and good mechanical support, is an important substrate for constructing self-supporting hydrogen evolution cathodes.

[0005] Metal-organic frameworks (MOFs) possess advantages such as tunable metal nodes, designable organic ligands, and easily regulated morphology, making them suitable for constructing self-supporting electrocatalysts with abundant active sites. Nickel foam-supported FeCo-MOF nanoflowers can form open nanosheet / petal assembly structures and can be used as electrocatalytic electrodes or precursors for further functionalization. However, when FeCo-MOF nanoflowers are directly used in alkaline hydrogen evolution reactions, they still suffer from insufficient intrinsic HER kinetics, limited control over the electronic structure of the metal center, and insufficient bubble impact and structural stability under high-current hydrogen evolution conditions.

[0006] Ru species exhibit high reactivity in hydrogen evolution reaction (HER). If Ru can be effectively introduced into the FeCo-MOF nanoflower system and synergistically interact with Ni species at the Fe, Co, and nickel foam interfaces, it is expected to improve the adsorption / desorption behavior of water splitting and hydrogen-related intermediates, thereby enhancing the performance of alkaline HER. However, the catalytic layer structure formed after Ru is introduced into the FeCo-MOF nanoflower system, the distribution morphology of Ru species, the electronic interactions between the Fe / Co / Ni / Ru multimetallic centers, and whether this structure can remain stable under industrial-grade high-current-density HER conditions, still lack clear structural design and preparation schemes.

[0007] Especially in anion exchange membrane water electrolysis devices, the cathode needs to withstand high current surges, rapid hydrogen evolution, bubble desorption disturbances, and long-term alkaline electrolysis environment. Therefore, it is necessary to develop a FeCoRu-MOF self-supporting hydrogen evolution cathode with nickel foam-supported FeCo-MOF nanoflowers as the structural precursor and Ru species regulation to achieve a synergistic improvement in high activity, high stability, and device adaptability. Summary of the Invention

[0008] To address the aforementioned issues, this invention proposes a nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode. This electrode uses nickel foam-supported FeCo-MOF nanoflowers as a precursor, introducing Ru species through a secondary solvothermal treatment in an ethanol solution containing a ruthenium source. This further transforms the original nanoflowers into a wrinkled nanoflower-like FeCoRu-MOF catalytic layer, and small Ru particles / clusters are formed on the nanopetals.

[0009] The resulting FeCoRu-MOF@NF self-supporting cathode differs from the FeCo-MOF@NF basic anode in its application and protection focus: FeCo-MOF@NF is mainly used as an oxygen evolution anode, while the FeCoRu-MOF@NF of this invention is mainly used as a hydrogen evolution cathode. This cathode can be directly used in alkaline HER and AEMWE devices without a binder. The wrinkled nanoflower structure helps to increase the electrolyte contact area, expose metal active sites, and promote the release of hydrogen bubbles. The electronic interactions between Ru particles / clusters and metal centers such as Fe, Co, and Ni can optimize the hydrogen evolution reaction kinetics, thereby reducing the hydrogen evolution overpotential under high current density and improving long-term operational stability.

[0010] The self-supporting hydrogen evolution cathode supported on nickel foam and FeCoRu-MOF wrinkled nanoflower-like structure provided by the present invention includes a nickel foam conductive substrate and an FeCoRu-MOF catalytic layer in situ supported on the surface of the nickel foam conductive substrate; The FeCoRu-MOF catalytic layer has a wrinkled nanoflower-like structure, which is assembled from nanosheet / petal-like units, and Ru particles / clusters are distributed on the surface or near the surface of the nanopetals.

[0011] In the nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode structure of this invention, the nickel foam provides a continuous conductive path and three-dimensional open channels; the FeCoRu-MOF wrinkled nanoflowers are assembled from nanosheet / petal-shaped units, possessing a large electrolyte contact area and abundant exposure sites; Ru particles / clusters are distributed on the nanopetals, which can interact electronically with metal centers such as Fe, Co, and Ni, modulating the electronic structure of metal sites and improving the kinetics of alkaline HER reaction. Compared with FeCo-MOF@NF, FeCoRu-MOF@NF has further limitations and distinctions in morphology, composition, electronic structure, and application direction.

[0012] In the nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode structure, the FeCoRu-MOF catalytic layer is formed by heat treatment of the FeCo-MOF nanoflower precursor with a ruthenium source.

[0013] The FeCo-MOF@NF was prepared by a method comprising the following steps: 1) Pretreatment of nickel foam; 2) The pretreated nickel foam is placed in a solvent containing an iron source, a cobalt source, and an organic ligand for a solvothermal reaction; 3) After the reaction is complete, the anode is washed and dried to obtain FeCo-MOF@NF nanoflower-like self-supporting oxygen evolution anode.

[0014] In step 2), the iron source is ferric nitrate nonahydrate. The cobalt source is cobalt chloride hexahydrate; The organic ligand is 2,5-dihydroxyterephthalic acid; The solvent is N,N-dimethylformamide; The ratio of ferric nitrate nonahydrate, cobalt chloride hexahydrate, 2,5-dihydroxyterephthalic acid and N,N-dimethylformamide is as follows: 100-300 mg: 100-300 mg: 50-150 mg: 20-40 mL. In step 2), the temperature of the solvothermal reaction is 100-160℃ and the time is 6-18 h.

[0015] Specifically, the nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode provided by the present invention is prepared by a method comprising the following steps: 1) Pretreatment of nickel foam; 2) The pretreated nickel foam was added to a mixed solution containing an iron source, a cobalt source, 2,5-dihydroxyterephthalic acid and N,N-dimethylformamide, and the first solvothermal reaction was carried out in a reactor to obtain the nickel foam-supported FeCo-MOF nanoflower precursor, denoted as FeCo-MOF@NF; 3) After drying the obtained FeCo-MOF@NF precursor, it was added to an ethanol solution containing a ruthenium source and carried out a second solvothermal reaction in a reactor. After cooling, washing and drying, a nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode was obtained, denoted as FeCoRu-MOF@NF.

[0016] The self-supporting cathode of this invention is grown directly on the surface of a nickel foam substrate without the need for additional binders. This reduces interfacial resistance and enhances the bond between the catalyst layer and the conductive substrate, which helps to rapidly remove bubbles and stabilize the electrode structure during high current density hydrogen evolution.

[0017] This invention constructs a FeCoRu-MOF@NF self-supporting cathode using a two-step in-situ solvothermal strategy. First, FeCo-MOF nanoflower precursors are grown in situ in an N,N-dimethylformamide solution containing iron, cobalt, and 2,5-dihydroxyterephthalic acid, using nickel foam as a conductive framework. Second, the FeCo-MOF@NF precursors are subjected to a secondary solvothermal treatment in an ethanol solution containing ruthenium, introducing Ru species and further transforming ordinary nanoflowers into a wrinkled nanoflower-like FeCoRu-MOF catalytic layer.

[0018] In step 1) of the above method, the pretreatment operation is as follows: the nickel foam sample is immersed in hydrochloric acid, deionized water and ethanol in sequence, and ultrasonically treated respectively, and then placed in a vacuum oven for vacuum drying.

[0019] The concentration of hydrochloric acid can be 0.5-2M, specifically 1M; The duration of the ultrasonic treatment can be 10-30 minutes, specifically 15 minutes; The vacuum drying temperature can be 50-60℃.

[0020] In step 2) of the above method, the iron source is ferric nitrate nonahydrate; The cobalt source is cobalt chloride hexahydrate; The ratio of ferric nitrate nonahydrate, cobalt chloride hexahydrate, 2,5-dihydroxyterephthalic acid and N,N-dimethylformamide can be: 100-300 mg: 100-300 mg: 50-150 mg: 20-40 mL, preferably 210 mg: 210 mg: 90 mg: 30 mL; The concentration of ferric nitrate nonahydrate in the mixed solution can be 5-8 mg / mL; preferably, it can be 7 mg / mL. More specifically, the addition ratio of each substance and component is as follows: nickel foam 2 cm × 2 cm or 5 cm × 5 cm, 2,5-dihydroxyterephthalic acid 90 mg, Fe(NO3)3·9H2O 210 mg, CoCl2·6H2O 210 mg, DMF 30 mL.

[0021] The temperature of the first solvothermal reaction can be 100-160℃, and the time can be 6-18 h; preferably, the temperature is 120℃ and the time is 12 h.

[0022] Preferably, the inner liner of the reactor is made of polytetrafluoroethylene. Preferably, the reactor is directly heated to 120°C, and the heating rate is set to 2.5°C / min; Preferably, the temperature of the heat preservation reaction is 120°C and the time is 12 hours.

[0023] In step 3), the ruthenium source can be ruthenium trichloride; Specifically, RuCl3·xH2O was added to ethanol and then thoroughly dispersed by ultrasonication to completely dissolve it, thus obtaining an ethanol solution containing the ruthenium source. The concentration of ruthenium trichloride in ethanol can be 3-4 mg / mL; preferably, it can be 3.33 mg / mL.

[0024] FeCo-MOF@NF precursor 2 cm×2 cm or 5 cm×5 cm, RuCl3·xH2O 90-120 mg (specifically 100 mg), ethanol 30 mL; The temperature of the second solvothermal reaction can be 110-150℃, and the time can be 1-3 h; preferably, the temperature is 130℃ and the time is 2 h.

[0025] Preferably, the inner liner of the reactor is made of Teflon material; Preferably, the reactor is directly heated to 130°C, and the heating rate is set to 2-3°C / min; Preferably, the temperature of the heat preservation reaction is 130°C and the time is 2 hours; Preferably, the mixture is cooled to room temperature.

[0026] Furthermore, after both solvothermal reactions, the following steps are also included: the obtained product is washed with ethanol to remove the unbonded active substances on the surface, and then vacuum dried in a vacuum oven at 50-60℃.

[0027] The application of the aforementioned nickel-fed FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode in water electrolysis for hydrogen production also falls within the scope of protection of this invention.

[0028] In the aforementioned application, the nickel-frozen FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode is used to electrolyze water to produce hydrogen at industrially relevant current densities.

[0029] In the aforementioned application, the nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode can be used for hydrogen evolution reaction (HER) in alkaline electrolytes, and exhibits low overpotential and good stability at high current densities.

[0030] In the three-electrode system, the FeCoRu-MOF@NF self-supporting hydrogen evolution cathode has hydrogen evolution overpotentials of 46.79 mV, 68.24 mV and 102.29 mV at current densities of -0.5 A / cm², -1 A / cm² and -2 A / cm², respectively, and can operate stably for 826 h at a current density of -2 A / cm².

[0031] The application of the aforementioned FeCoRu-MOF@NF self-supporting hydrogen evolution cathode as the cathode of an AEM anion exchange membrane water electrolysis device also falls within the protection scope of this invention.

[0032] The present invention also provides an anion exchange membrane water electrolysis device.

[0033] The cathode of the anion exchange membrane water electrolysis device is made using the aforementioned FeCoRu-MOF@NF self-supporting hydrogen evolution cathode.

[0034] The FeCoRu-MOF@NF self-supporting hydrogen evolution cathode can be assembled with the FeCo-MOF@NF self-supporting oxygen evolution anode and a commercial anion exchange membrane to form an AEMWE device with an effective area of ​​4 cm², and tested in 1 M KOH electrolyte. In this device, FeCoRu-MOF@NF serves as the cathode to be verified, and FeCo-MOF@NF serves as the matching anode. Under conditions of 60 °C and 2.0 A / cm², the device corresponds to a total current of 8 A and can operate stably for approximately 2200 h, indicating that the cathode of this invention has good device adaptability and long-term operating potential.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention constructs a nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode. This structure requires no binder, enhances the contact between the catalyst layer and the conductive substrate, reduces interfacial resistance, and improves structural stability during high current density hydrogen evolution processes.

[0036] 2. This invention uses FeCo-MOF nanoflowers as precursors and introduces Ru species through a secondary solvothermal treatment with a ruthenium source, further transforming the original nanoflowers into a wrinkled nanoflower morphology, and forming small Ru particles / clusters on the nanopetals. This technical approach retains the open structure of FeCo-MOF nanoflowers while endowing the material with Ru active sites suitable for HER and multimetallic electronic regulation characteristics.

[0037] 3. In this invention, there are obvious electronic interactions between metal centers such as Fe, Co, Ni, and Ru. After the introduction of Ru, FeCoRu-MOF@NF shows a significant shift in the XPS peaks related to Fe, Co, and Ni compared to FeCo-MOF@NF, indicating that the electronic structure of the metal centers is regulated, which is beneficial to improving the water decomposition and hydrogen-related intermediate adsorption / desorption behavior during alkaline hydrogen evolution.

[0038] 4. The FeCoRu-MOF@NF self-supporting hydrogen evolution cathode described in this invention exhibits excellent HER activity in a three-electrode system, with overpotentials of 46.79 mV, 68.24 mV, and 102.29 mV at -0.5 A / cm², -1 A / cm², and -2 A / cm², respectively, which are superior to FeCo-MOF@NF and commercial 20 wt% Pt / C catalyst comparison samples, and can operate stably at -2 A / cm² for 826 h.

[0039] 5. The FeCoRu-MOF@NF self-supporting hydrogen evolution cathode described in this invention can be used in AEMWE devices. After being assembled with the FeCo-MOF@NF self-supporting oxygen evolution anode and a commercial anion exchange membrane in 1 M KOH, it can operate stably for about 2200 h under conditions of 4 cm² effective area, 60℃, and 2.0 A / cm², indicating that it has good device adaptability and promising prospects for hydrogen production applications with relevant industrial current densities. Attached Figure Description

[0040] Figure 1 SEM images of FeCoRu-MOF@NF and FeCo-MOF@NF prepared in the embodiments of the present invention. Among them, (af) is the SEM image of FeCoRu-MOF@NF at different magnifications, showing the morphology of wrinkled nanoflowers assembled from wrinkled nanosheets / petals; (gi) is the SEM image of FeCo-MOF@NF comparative example at different magnifications, showing the nanoflower morphology.

[0041] Figure 2 The SEM-mapping image of FeCoRu-MOF@NF prepared in this embodiment of the invention shows that C, O, Fe, Co, Ni and Ru elements are uniformly distributed in the catalyst region.

[0042] Figure 3 TEM and HRTEM images of FeCoRu-MOF@NF prepared in this embodiment of the invention show its nanopetal structure and Ru particles / clusters distributed on the petals.

[0043] Figure 4 The HRTEM-mapping image of FeCoRu-MOF@NF prepared in this embodiment of the invention shows that C, O, Fe, Co, Ni and Ru elements are uniformly distributed in the micro-region of a single nanoflower / nanofamber.

[0044] Figure 5 The high-resolution XPS spectrum of FeCoRu-MOF@NF prepared for this embodiment of the invention includes the C 1s, O 1s, Fe 2p, Co 2p, Ni 2p and Ru related spectral regions.

[0045] Figure 6 The XPS comparison images of Fe 2p, Co 2p and Ni 2p of FeCoRu-MOF@NF and FeCo-MOF@NF prepared in the embodiments of the present invention show that the electronic structure of the related metal centers of Fe, Co and Ni changes significantly after the introduction of Ru.

[0046] Figure 7 The figures show the HER performance of the FeCoRu-MOF@NF three-electrode system prepared in this embodiment of the invention. Among them, (a) shows the LSV polarization curve and the comparison of overpotential of different samples at high current density; (b) shows the stability test curve of FeCoRu-MOF@NF at a current density of -2 A / cm².

[0047] Figure 8 The image shows the performance of the AEMWE device assembled with FeCoRu-MOF@NF as the cathode and FeCo-MOF@NF as the anode in this embodiment of the invention, including polarization curves at different temperatures and long-term stability test curves under conditions of 60℃ and 2.0 A / cm². Detailed Implementation

[0048] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0049] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0050] Example: Preparation of a nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode 1. Preparation of FeCo-MOF74 nanoflower precursors The required nickel foam for synthesis underwent pretreatment: Nickel foam samples with dimensions of 2×2 cm or 5×5 cm were sequentially immersed in 1 M hydrochloric acid, deionized water, and ethanol, and ultrasonically treated for 15 min each, followed by vacuum drying at 50-60℃ in a vacuum oven. Subsequently, the required reaction mixture was prepared at room temperature: 90 mg of 2,5-dihydroxyterephthalic acid (H4DOT), 210 mg of ferric nitrate nonahydrate (Fe(NO3)3·9H2O), and 210 mg of cobalt chloride hexahydrate (CoCl2·6H2O) were weighed into a sealed container, and then 30 mL of N,N-dimethylformamide (DMF) was added and dissolved completely. This mixture was transferred to a 50 mL polytetrafluoroethylene-lined reactor, and the pretreated nickel foam was added for subsequent synthesis reactions.

[0051] The reactor was transferred to an oven, and a temperature control program was set to raise the temperature from room temperature to 120°C at a rate of approximately 2.5°C / min and maintain this temperature for 12 h. After the reactor cooled naturally to room temperature, the catalyst was removed and rinsed three times with ethanol. Subsequently, the catalyst was placed in a vacuum oven and vacuum dried at 55°C for 7 h to obtain the FeCo-MOF@NF nanoflower precursor.

[0052] 2. Preparation of FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode 100 mg of ruthenium trichloride (RuCl3·xH2O) was weighed and placed in a sealed container. 30 mL of ethanol was added, and a homogeneous ruthenium-containing ethanol solution was prepared by ultrasonic dispersion. This solution was then transferred to a 50 mL polytetrafluoroethylene (PTFE) liner, and dried FeCo-MOF@NF nanoflower precursors were added. The liner was sealed in a high-pressure reactor, which was then transferred to an oven. A temperature control program was set to raise the temperature from room temperature to 130 °C at a rate of approximately 2.5 °C / min and maintained for 2 h. After the reaction was complete, the reactor was allowed to cool naturally to room temperature. The catalyst was then removed and washed three times sequentially with water and ethanol. Subsequently, the catalyst was placed in a vacuum oven and dried under vacuum at 55-60 °C to obtain a FeCoRu-MOF@NF wrinkled nanoflower-shaped self-supporting hydrogen evolution cathode.

[0053] 3. Component assembly and performance testing In the three-electrode HER test, a FeCoRu-MOF@NF self-supporting cathode was used as the working electrode, an Hg / HgO electrode as the reference electrode, a carbon rod as the counter electrode, and 1 M KOH solution as the electrolyte. Hydrogen evolution activity was evaluated using linear sweep voltammetry (LSV), and constant current stability was tested at a current density of -2 A / cm². In the AEMWE device test, FeCoRu-MOF@NF was used as the cathode to be verified, FeCo-MOF@NF as the matching anode, and a commercial anion exchange membrane was used as the separator to assemble an anion exchange membrane water electrolysis device with an effective area of ​​4 cm². Testing was conducted in 1 M KOH. The commercial anion exchange membrane can be a Versogen A series anion exchange membrane.

[0054] The morphology and elemental distribution of the prepared FeCoRu-MOF@NF were characterized, and the results are as follows: Figure 1 and Figure 2 As shown. Figure 1 The results show that FeCoRu-MOF@NF forms a wrinkled nanoflower-like structure assembled from wrinkled nanosheets / petals on the surface of nickel foam. This structure has open channels and abundant surface wrinkles, which is beneficial for electrolyte wetting and hydrogen bubble release. Figure 1 In the example, gi represents FeCo-MOF@NF, which exhibits a typical nanoflower morphology. In contrast, FeCoRu-MOF@NF with Ru incorporation displays more pronounced wrinkled nanosheet assembly and surface undulation characteristics. Figure 2 SEM-mapping results showed that C, O, Fe, Co, Ni and Ru elements were uniformly distributed in the FeCoRu-MOF@NF catalyst region, indicating that Ru species were successfully introduced and the overall composition was uniformly distributed.

[0055] The microstructure of FeCoRu-MOF@NF was further characterized by TEM, HRTEM, and HRTEM-mapping, and the results are as follows: Figure 3 and Figure 4 As shown. Figure 3 The results show that FeCoRu-MOF@NF maintains the nanoflower / nanosheet assembly structure, and many small Ru particles / clusters can be observed on the nanopetals, indicating that the second solvothermal treatment with a ruthenium source can introduce Ru active species on the basis of FeCo-MOF nanoflowers and construct Ru-modified wrinkled nanoflower structures. Figure 4 The HRTEM-mapping results further demonstrate that C, O, Fe, Co, Ni, and Ru elements are uniformly distributed within the microscopic nanoflower region, indicating that FeCoRu-MOF@NF has a uniform multi-element composition and good structural integrity.

[0056] pass Figure 5The elemental composition and chemical state of FeCoRu-MOF@NF were analyzed using high-resolution XPS spectra. The C1s spectrum can be attributed to CC / C=C, CO, and carboxyl-related carbon species in the MOF organic ligands; the O 1s spectrum can be attributed to metal-oxygen coordination, carboxyl / hydroxyl groups, and surface-adsorbed oxygen species; the Fe 2p and Co 2p spectra show that the Fe and Co metal centers exist in multiple valence states, accompanied by corresponding satellite peaks; the Ni 2p spectrum mainly originates from the nickel foam substrate and its surface coordination / oxide species; the Ru-related spectral region indicates that Ru species were successfully introduced into the FeCo-MOF@NF system, forming Ru particles / clusters or Ru-related coordination species. These results demonstrate that the FeCoRu-MOF@NF prepared in this invention simultaneously contains C, O, Fe, Co, Ni, and Ru elements, forming a multi-metal synergistic MOF-based self-supporting cathode structure.

[0057] Figure 6 The XPS diagrams for Fe 2p, Co 2p, and Ni 2p peaks are shown for FeCoRu-MOF@NF and FeCo-MOF@NF. Compared to FeCo-MOF@NF, FeCoRu-MOF@NF shows identifiable shifts in the Fe, Co, and Ni related peaks, indicating that the electronic environment of the FeCo-MOF matrix and the metal center at the nickel foam interface changes after Ru introduction. This electronic structure adjustment is beneficial for optimizing water decomposition and the adsorption / desorption behavior of hydrogen-related intermediates during alkaline hydrogen evolution, thereby improving the HER reaction kinetics. Since C 1s and O 1s mainly reflect the organic ligands, carboxyl / hydroxyl groups, and surface adsorbed species of MOF, this example mainly selects the Fe, Co, and Ni related spectral regions as the basis for comparing the changes in electronic structure before and after Ru introduction.

[0058] Figure 7 The results show the HER performance of FeCoRu-MOF@NF in a three-electrode system. Figure 7 As shown in Figure a, the overpotentials of FeCoRu-MOF@NF at current densities of -0.5 A / cm², -1 A / cm², and -2 A / cm² are 46.79 mV, 68.24 mV, and 102.29 mV, respectively, significantly lower than those of the FeCo-MOF@NF comparative sample (446.81 mV and 547.40 mV at -0.5 A / cm² and -1 A / cm², respectively), and also superior to those of the commercial 20% Pt / C comparative sample (155.05 mV, 242.78 mV, and 351.42 mV at -0.5 A / cm², -1 A / cm², and -2 A / cm², respectively). These results indicate that the FeCoRu-MOF@NF obtained by introducing Ru exhibits excellent alkaline hydrogen evolution activity at industrially relevant high current densities. Figure 7As shown in Figure b, FeCoRu-MOF@NF can operate stably for 826 h at a current density of -2 A / cm², indicating that it has good structural stability and durability under high current hydrogen evolution conditions.

[0059] FeCoRu-MOF@NF was used as the cathode to be verified, and FeCo-MOF@NF (the FeCo-MOF@NF nanoflower precursor in Example 1) was used as the matching anode. A commercial anion exchange membrane (Versogen A series anion exchange membrane) was used as the separator to assemble an AEMWE device with an effective area of ​​4 cm², and the results were tested in 1 M KOH. Figure 8 As shown, at 25°C, the cell voltages of the AEMWE device at current densities of 0.5 A / cm², 1.795 V, and 2.137 V are approximately 1.588 V, 1.795 V, and 2.137 V, respectively; at 60°C, the corresponding cell voltages are approximately 1.482 V, 1.644 V, and 1.915 V, respectively; and at 70°C, the corresponding cell voltages are approximately 1.446 V, 1.573 V, and 1.817 V, respectively. The cell voltages further decrease with increasing temperature, indicating that the FeCoRu-MOF@NF self-supporting hydrogen evolution cathode has good compatibility with the AEMWE device.

[0060] Under conditions of 60℃, 1 M KOH, and 2.0 A / cm², the 4 cm² AEMWE device corresponds to a total current of 8 A and can operate stably for approximately 2200 h. This result demonstrates that the AEMWE device assembled using FeCoRu-MOF@NF as the cathode is suitable for long-term anion exchange membrane water electrolysis operation at industrially relevant current densities, further proving the promising practical application prospects of the self-supporting hydrogen evolution cathode of this invention.

[0061] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope, and without requiring unnecessary experiments. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including changes made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. A nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode, comprising: Nickel foam conductive substrate and FeCoRu-MOF catalyst layer in situ supported on the surface of said nickel foam conductive substrate.

2. The nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode according to claim 1, characterized in that, The FeCoRu-MOF catalytic layer has a wrinkled nanoflower-like structure, which is assembled from nanosheet / petal-like units, and Ru particles / clusters are distributed on the surface or near the surface of the nanopetals.

3. The nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode according to claim 1, characterized in that, In the nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode structure, the FeCoRu-MOF catalytic layer is formed by heat treatment of the FeCo-MOF nanoflower precursor with a ruthenium source.

4. A method for preparing a nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode according to any one of claims 1-3, comprising the following steps: 1) Pretreatment of nickel foam; 2) The pretreated nickel foam was added to a mixed solution containing an iron source, a cobalt source, 2,5-dihydroxyterephthalic acid and N,N-dimethylformamide, and the first solvothermal reaction was carried out in a reactor to obtain the nickel foam-supported FeCo-MOF nanoflower precursor, FeCo-MOF@NF; 3) After drying the obtained FeCo-MOF@NF precursor, it was added to an ethanol solution containing ruthenium source and carried out a second solvothermal reaction in a reactor. After cooling, washing and drying, a nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode, FeCoRu-MOF@NF, was obtained.

5. The method according to claim 4, characterized in that, In step 1), the pretreatment operation is as follows: the nickel foam sample is immersed in hydrochloric acid, deionized water and ethanol in sequence, and ultrasonically treated respectively, and then vacuum dried.

6. The method according to claim 4, characterized in that, In step 2), the iron source is ferric nitrate nonahydrate; The cobalt source is cobalt chloride hexahydrate; The ratio of ferric nitrate nonahydrate, cobalt chloride hexahydrate, 2,5-dihydroxyterephthalic acid and N,N-dimethylformamide is: 100-300 mg: 100-300 mg: 50-150 mg: 20-40 mL; The concentration of ferric nitrate nonahydrate in the mixed solution is 5-8 mg / mL; The temperature of the first solvothermal reaction is 100-160℃, and the time is 6-18 h.

7. The method according to claim 4, characterized in that, In step 3), the ruthenium source is ruthenium trichloride; RuCl3·xH2O was added to ethanol and then thoroughly dispersed by ultrasonication to completely dissolve it, resulting in an ethanol solution containing the ruthenium source. The concentration of ruthenium trichloride in ethanol is 3-4 mg / mL; FeCo-MOF@NF precursor 2 cm×2 cm or 5 cm×5 cm, RuCl3·xH2O 90-120 mg, ethanol 30 mL; The second solvothermal reaction is carried out at a temperature of 110-150℃ for 1-3 hours.

8. The application of the nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode according to any one of claims 1-3 in hydrogen production by water electrolysis; In the aforementioned application, the nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode is used to electrolyze water to produce hydrogen at industrially relevant current densities.

9. The application according to claim 8, characterized in that, In the aforementioned application, the nickel foam-supported FeCoRu-MOF wrinkled nanoflower-like self-supporting hydrogen evolution cathode is used for the hydrogen evolution reaction (HER) in alkaline electrolytes, and exhibits low overpotential and good stability at high current densities.

10. An anion exchange membrane water electrolysis device, wherein the cathode of the anion exchange membrane water electrolysis device is made of a nickel foam-supported FeCoRu-MOF pleated nanoflower-like self-supporting hydrogen evolution cathode as described in any one of claims 1-3.

Images