A method for preparing and applying high-entropy NiFeCuCoRu hydroxide
By employing a two-step preparation strategy involving solvothermal method and electrochemical reduction, the complex preparation process of high-entropy hydroxides was solved, enabling the simplified preparation of high-entropy NiFeCuCoRu hydroxides. This improved the stability and catalytic performance of the materials and optimized the activity and efficiency of the electrocatalytic reaction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- OCEAN UNIV OF CHINA
- Filing Date
- 2026-02-04
- Publication Date
- 2026-05-26
AI Technical Summary
Existing processes for preparing high-entropy hydroxides often involve harsh conditions and complex procedures, resulting in insufficient material stability and poor reproducibility of catalytic performance, making it difficult to meet the requirements of high-performance electrocatalysis.
A two-step preparation strategy combining solvothermal method and electrochemical reduction was adopted. Nickel salt, iron salt, copper salt, cobalt salt and ruthenium salt were used as metal sources and terephthalic acid was used as ligand. High-entropy NiFeCuCoRu hydroxide was prepared by ultrasonic treatment, solvothermal reaction, solid-liquid separation and electrochemical reduction, so as to ensure uniform distribution of metal elements and optimized electrocatalytic performance.
A simplified preparation of high-entropy NiFeCuCoRu hydroxide was achieved, ensuring the structural stability and enhanced catalytic activity of the material. The d-band center and charge transfer efficiency of the catalyst were optimized, exhibiting low overpotential and fast electrocatalytic reaction kinetics.
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Figure CN122079261A_ABST
Abstract
Description
[0001] This invention belongs to the field of water electrolysis oxygen evolution reaction technology, and particularly relates to a high-entropy NiFeCuCoRu hydroxide, its preparation method and application. Background Technology
[0003] Against the backdrop of a worsening global energy crisis, electrochemical water splitting technology is considered one of the most promising pathways for green hydrogen production. However, the oxygen evolution reaction (OER) at the anodic stage of these technologies suffers from a significant energy loss due to its inherently high activation energy barrier, resulting in a large overpotential. This has become a key factor limiting the efficiency of water splitting. Therefore, developing efficient, stable, and low-cost OER catalysts is currently a research hotspot.
[0004] Traditional single-metal or bimetallic hydroxide catalysts often suffer from insufficient active sites and poor electronic conductivity, making it difficult to meet the demands of high-performance electrocatalysis. In recent years, high-entropy materials (HEMs) have gradually become an important platform for oxygen evolution reaction research due to their unique structural characteristics and the advantages of diversified component regulation.
[0005] High-entropy materials, with their synergistic effects of multi-metal components, unique lattice distortion, and electronic structure modulation advantages, offer a new direction for overcoming the performance bottlenecks of traditional catalysts. High-entropy hydroxides, through the atomic-level uniform distribution of multiple metal elements, can optimize the d-band centers of the catalyst, enrich the number of active sites, and enhance charge transfer efficiency. Simultaneously, their stable solid solution structure effectively resists structural damage and component loss during the reaction process. However, existing high-entropy hydroxide preparation processes often suffer from harsh conditions and complex procedures, making it difficult for the prepared materials to fully utilize their inherent structural advantages, resulting in insufficient stability and poor reproducibility of catalytic performance. Therefore, developing a high-entropy hydroxide material with a simple, green, and controllable preparation process, possessing both excellent oxygen evolution reaction catalytic activity and structural stability, has become a pressing technical challenge in the field of electrocatalytic materials. Summary of the Invention
[0007] This invention employs a two-step preparation strategy combining solvothermal and electrochemical reduction. Using nickel, iron, copper, cobalt, and ruthenium salts as metal sources, terephthalic acid (H₂BDC) as a ligand, and a mixture of N,N-dimethylformamide (DMF) and sodium hydroxide (NaOH) as a solvent, high-entropy NiFeCuCoRu hydroxide is prepared through ultrasonic treatment, solvothermal reaction, solid-liquid separation, vacuum drying, and electrochemical reduction. This preparation method is simple, mild, and easily scalable. Ultrasonic dispersion ensures uniform complexation of metal ions and ligands, effectively avoiding the component segregation problem in multi-metal systems and guaranteeing atomic-level uniform distribution of metal elements in the product. Subsequent electrochemical reduction further modulates the phase structure and electronic states of the product, endowing the material with superior electrocatalytic reaction sites and charge transfer efficiency.
[0008] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing high-entropy NiFeCuCoRu hydroxide, comprising the following steps:
[0009] S1. Take nickel salt, iron salt, copper salt, cobalt salt, ruthenium salt and terephthalic acid (H2BDC) and dissolve them in a mixed solvent of N,N-dimethylformamide (DMF) and sodium hydroxide (NaOH) in a predetermined ratio;
[0010] S2. The mixed solution in S1 is ultrasonically treated to ensure that all components are fully dissolved;
[0011] S3. After transferring the fully dissolved homogeneous solution to a high-pressure reactor and sealing it, place it in an oven for a solvothermal reaction at a preset temperature and time.
[0012] S4. After the reaction is complete, the resulting suspension is separated into solid and liquid by centrifugation, the precipitate is collected and dried in a vacuum drying oven.
[0013] S5. The dried product is subjected to electrochemical reduction treatment to obtain the target high-entropy NiFeCuCoRu hydroxide.
[0014] The high-entropy NiFeCuCoRu hydroxide prepared by the above method is used as a catalyst or electrode material for oxygen evolution at the anode in alkaline water electrolysis for hydrogen production.
[0015] Compared with related technologies, the beneficial effects of the present invention are as follows:
[0016] 1. The method for preparing high-entropy NiFeCuCoRu hydroxide provided by this invention is simple and operates under mild conditions. Ultrasonic dispersion ensures uniform complexation between the metal salt and ligands, effectively avoiding the component segregation problem common in multi-metal systems and guaranteeing atomic-level uniform distribution of the five metal elements in the high-entropy hydroxide. This provides a structural basis for the stability of subsequent catalytic performance.
[0017] 2. The high-entropy NiFeCuCoRu hydroxide obtained in this invention optimizes the adsorption energy of the d-band center and oxygen intermediate of the catalyst through the mutual modulation of the electronic structure of multiple metals. This makes the material exhibit superior intrinsic activity for the oxygen evolution reaction, achieving lower overpotential and faster reaction kinetics under alkaline conditions. Compared with traditional single-metal or bimetallic hydroxides, its catalytic activity is significantly improved, providing a highly efficient and stable catalytic material for the anodic oxygen evolution reaction in alkaline water electrolysis for hydrogen production. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. These drawings are incorporated in and constitute a part of this specification, illustrating embodiments consistent with the present invention, and together with the description, serve to explain the principles of the invention.
[0020] Figure 1 This is a flowchart illustrating the preparation process of the high-entropy NiFeCuCoRu hydroxide provided by the present invention.
[0021] Figure 2 These are the X-ray diffraction patterns of the transition metal hydroxides prepared in Example 1 and Comparative Examples 1-3 of this invention.
[0022] Figure 3 These are scanning electron microscope images of the materials prepared in Comparative Examples 1-3 and Example 1 of this invention before electrochemical reduction. (a) NiBDC; (b) NiFeBDC; (c) NiFeRuBDC; (d) NiFeCuCoRuBDC.
[0023] Figure 4 These are field emission electron microscope images of the materials prepared in Comparative Example 1 and Example 1 of the present invention, wherein (a) NiOOH; (b) NiFeCuCoRuOOH;
[0024] Figure 5 These are field emission electron microscope images and elemental distribution diagrams of nickel, iron, copper, cobalt, ruthenium, and oxygen of the material prepared in Example 1 of this invention.
[0025] Figure 6 These are the Raman spectra of the materials prepared in Comparative Example 1 and Example 1 of this invention.
[0026] Figure 7 This is a linear sweep voltammetric characteristic (LSV) curve of the oxygen evolution reaction in a single electrolytic cell for the materials prepared in Example 1 and Comparative Examples 1-3 of this invention.
[0027] Figure 8This is a linear sweep voltammetric characteristic (LSV) curve of the oxygen evolution reaction of the materials prepared in Example 1 and Comparative Examples 1-3 of the present invention in a fluid electrolytic cell. Detailed Implementation
[0029] The present invention will be further described below with reference to the accompanying drawings and examples:
[0030] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0032] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. The invention will be further described below with reference to the accompanying drawings and examples:
[0033] Combination Figure 1 As shown, this invention provides a method for preparing high-entropy NiFeCuCoRu hydroxide, comprising the following steps:
[0034] S1. Take nickel salt, iron salt, copper salt, cobalt salt, ruthenium salt and terephthalic acid (H2BDC) and dissolve them in a mixed solvent of N,N-dimethylformamide (DMF) and sodium hydroxide (NaOH) in a predetermined ratio;
[0035] S2. The mixed solution in S1 is ultrasonically treated to ensure that all components are fully dissolved;
[0036] S3. After transferring the fully dissolved homogeneous solution to a high-pressure reactor and sealing it, place it in an oven for a solvothermal reaction at a preset temperature and time.
[0037] S4. After the reaction is complete, the resulting suspension is separated into solid and liquid by centrifugation, the precipitate is collected and dried in a vacuum drying oven.
[0038] S5. The dried product is subjected to electrochemical reduction treatment to obtain the target high-entropy NiFeCuCoRu hydroxide.
[0039] Based on the above technical solution, the total molar amount of nickel salt, iron salt, copper salt, cobalt salt and ruthenium salt in S1 is 1 mmol, the molar amount of terephthalic acid is 1~4 mmol, the volume of N,N-dimethylformamide in S1 is 1~5 mL, and the concentration of sodium hydroxide solution is 0.4 mol / L, with a volume of 1~5 mL.
[0040] Based on the above technical solution, the nickel salt, iron salt, copper salt, cobalt salt, and ruthenium salt in S1 are nickel chloride hexahydrate, ferric chloride hexahydrate, copper chloride, cobalt chloride, and ruthenium chloride, respectively, and their molar ratio is 8.5:1:0.1:0.1:0.3.
[0041] Based on the above technical solution, in step S2, the ultrasonic power is 200~400 watts and the ultrasonic time is 5~60 minutes.
[0042] Based on the above technical solution, the heating rate in S3 is 1~10℃ / min, the oven setting temperature is 100~150℃, and the solvothermal reaction time is 12~24 hours.
[0043] Based on the above technical solution, in step S4, the centrifugation speed is 6000~10000 rpm, the centrifugation time is 5~15 minutes, the washing solvent is N,N-dimethylformamide or ethanol, the number of washings is 3~6, the vacuum drying temperature is 60~100℃, and the time is 6~24h.
[0044] Based on the above technical solution, in step S5, a Chenhua electrochemical workstation is used to perform electrochemical reduction and activation by cyclic voltammetry to obtain the target high-entropy NiFeCuCoRu hydroxide.
[0045] Secondly, the present invention provides a method for preparing high-entropy NiFeCuCoRu hydroxide, which is prepared according to the method for preparing high-entropy NiFeCuCoRu hydroxide described in any of the above embodiments.
[0046] Thirdly, the present invention provides a method for preparing high-entropy NiFeCuCoRu hydroxide, and the application of the high-entropy NiFeCuCoRu hydroxide obtained by this invention as a catalyst or electrode material for oxygen evolution at the anode in alkaline water electrolysis for hydrogen production.
[0047] This invention utilizes nickel-based metal-organic frameworks (MOFs) as precursors to successfully construct high-entropy hydroxide materials with heritable morphology and highly tunable composition via a simple hydrothermal method. This method leverages chemical etching and reconstruction mechanisms to achieve the conversion from MOFs to high-entropy hydroxides under mild conditions, avoiding the energy consumption and agglomeration problems associated with high-temperature calcination. The resulting material combines the stability of MOFs with the electronic structure advantages of high-entropy materials, exhibiting low overpotential, rapid kinetics, and an ultra-long lifespan in the electrocatalytic oxygen evolution reaction (OER). This preparation strategy offers advantages such as simple operation, good reproducibility, and ease of scale-up production, providing a practical new approach for the development of high-performance, low-cost OER catalysts.
[0048] Example 1
[0049] This embodiment provides a method for preparing high-entropy NiFeCuCoRu hydroxide, including the following steps:
[0050] S1. Take 1 mmol of nickel chloride hexahydrate, ferric chloride hexahydrate, copper chloride, cobalt chloride and ruthenium chloride in a molar ratio of 8.5:1:0.1:0.1:0.3 and dissolve 1 mmol of terephthalic acid in a mixed solvent of 6.5 mL of N,N-dimethylformamide and 1 mL of sodium hydroxide with a concentration of 0.4 mol / L.
[0051] S2. Sonicate the mixed solution in S1 for 10 minutes to fully dissolve each component;
[0052] S3. After transferring the fully dissolved homogeneous solution to the high-pressure reactor and sealing it, the preset heating rate is 5℃ / min, the oven temperature is set to 120℃, and the solvothermal reaction time is 15 hours.
[0053] S4. After the reaction is complete, the resulting suspension is separated into solid and liquid by centrifugation at a speed of 10,000 rpm for 10 minutes. The washing solvent is N,N-dimethylformamide, and the washing is performed 3 times. The vacuum drying temperature is 80℃ and the time is 12 hours.
[0054] S5. The dried product was electrochemically reduced and activated using a Chenhua electrochemical workstation via cyclic voltammetry to obtain the target high-entropy NiFeCuCoRu hydroxide: NiFeCuCoRuOOH.
[0055] Comparative Example 1
[0056] The preparation method of this embodiment is the same as that of Example 1, and the same parts are omitted. The difference from Example 1 is that in the comparative example, the amount of nickel chloride hexahydrate used in S1 is 1 mmol, and no other metal salts are used, and the final result is Comparative Example 1: NiOOH.
[0057] Comparative Example 2
[0058] The preparation method of this embodiment is the same as that of Example 1, and the same parts are omitted. The difference from Example 1 is that in this embodiment, the total amount of nickel chloride hexahydrate and ferric chloride hexahydrate used in S1 is 1 mmol, and the molar ratio of nickel chloride hexahydrate and ferric chloride hexahydrate is 9:1, and finally Comparative Example 2: NiFeOOH is obtained.
[0059] Comparative Example 3
[0060] The preparation method of this embodiment is the same as that of Example 1, and the same parts are omitted. The difference from Example 1 is that in this embodiment, the total amount of nickel chloride hexahydrate, ferric chloride hexahydrate and ruthenium chloride used in S1 is 1 mmol, and the molar ratio of nickel chloride hexahydrate, ferric chloride hexahydrate and ruthenium chloride is 8.5:1:0.5, and finally Comparative Example 3: NiFeRuOOH is obtained.
[0061] The catalytic activity of the single-cell reactor was tested using a three-electrode system, with a carbon rod as the counter electrode and a saturated silver / silver chloride electrode as the reference electrode. The area of the electrode loaded with samples from Example 1 and Comparative Examples 1-3 was 0.5 cm². 2 Nickel foam (NF) was used as the working electrode, and 1 mol / L potassium hydroxide solution was used as the electrolyte. Electrochemical activation was performed using cyclic voltammetry, with the potential range during the test being 1.1–1.8 V (vs. RHE).
[0062] Electroreduction performance was tested in a flow electrolytic cell using a three-electrode system. Carbon paper loaded with samples from Examples 1 and 1-3 was used as the working electrode, a saturated silver / silver chloride electrode as the reference electrode, and nickel foam as the counter electrode. A 1 mol / L potassium hydroxide solution was used as the electrolyte. The electrodes were separated by a 110–150 μm thick FAA-3PK-130 anion exchange membrane, with a catalyst loading of approximately 1.5 mg / cm³. 2 The electrolyte was circulated through the anion exchange membrane electrolyzer at a flow rate of 30 mL / min in a serpentine channel, and the potential range during the test was 1.1–1.8 V (vs. RHE).
[0063] Figure 1 This is a flowchart of the preparation process of high-entropy NiFeCuCoRu hydroxide.
[0064] Figure 2These are the X-ray diffraction patterns of the materials prepared in Example 1 and Comparative Examples 1-3 of this invention before electrochemical reduction. The figures show that the diffraction peaks of the metal-organic framework after transition metal doping are identical to the characteristic (2,0,0) plane of NiBDC, indicating a similar crystal structure. Notably, NiFeCuCoRuBDC exhibits the sharpest and strongest diffraction peaks. This demonstrates that introducing multiple metals (Fe, Cu, Co, Ru) into the NiBDC framework not only preserves the crystallinity of the parent material but also enhances its structural order.
[0065] Figure 3 These are scanning electron microscope images of the materials prepared in Comparative Examples 1-3 and Example 1 before electrochemical reduction. Both Comparative Examples 1-3 and Example 1 exhibit a dense nanoflower structure.
[0066] Figure 4 These are scanning electron microscope images of the materials prepared in Comparative Example 1 and Example 1 of this invention. NiOOH and NiFeCuCoRuOOH retain a flower-like hierarchical structure, with NiFeCuCoRuOOH exhibiting typical short-range order characteristics of high-entropy materials. This structure helps to expose more active sites.
[0067] Figure 5 This is a field emission electron microscope image of the material prepared in Example 1 of the present invention, and an elemental distribution diagram of nickel, iron, copper, cobalt, ruthenium, and oxygen. NiFeCuCoRuOOH still retains a uniform lamellar structure, and the elements of nickel, iron, copper, cobalt, ruthenium, and oxygen are uniformly distributed.
[0068] Figure 6 These are the Raman spectra of the materials prepared in Comparative Example 1 and Example 1 of this invention before electrochemical reduction. Comparative analysis shows that at 516 cm⁻¹... -1 and 696 cm -1 The presence of two additional peaks, corresponding to Ru-O and Ru-O-Ni bonds respectively, confirms the successful incorporation of Ru and other transition metals.
[0069] Figure 7 This is a linear sweep voltammetric (LSV) curve of the oxygen evolution reaction of the high-entropy NiFeCuCoRu hydroxides prepared in Example 1 and Comparative Examples 1-3 of this invention in a single electrolytic cell. Among them, NiFeCuCoRuOOH exhibits the smallest overpotential under the same driving current density.
[0070] Figure 8This is a linear sweep voltammetric (LSV) curve of the oxygen evolution reaction of the high-entropy NiFeCuCoRu hydroxides prepared in Example 1 and Comparative Examples 1-3 of this invention in a fluid electrolytic cell. Under the same driving current density, NiFeCuCoRuOOH exhibits the smallest overpotential, and the overpotential remains well maintained even at high current densities.
[0071] In summary, the high-entropy NiFeCuCoRu hydroxide prepared by this invention has a uniform composition and stable structure. The preparation process is mild, controllable, green, and environmentally friendly. Relying on the high-entropy synergistic effect, the electronic structure and adsorption energy of oxygen intermediates are optimized, resulting in excellent intrinsic OER catalytic activity and structural stability.
[0072] The present invention has been described above by way of example, but the present invention is not limited to the specific embodiments described above. Any modifications or variations made based on the present invention shall fall within the scope of protection claimed by the present invention.
Claims
1. A method for preparing high-entropy NiFeCuCoRu hydroxide, characterized in that, Includes the following steps: S1. Take nickel salt, iron salt, copper salt, cobalt salt, ruthenium salt and terephthalic acid (H2BDC) and dissolve them in a mixed solvent of N,N-dimethylformamide (DMF) and sodium hydroxide (NaOH) in a predetermined ratio; S2. The mixed solution in S1 is ultrasonically treated to ensure that all components are fully dissolved; S3. After transferring the fully dissolved homogeneous solution to a high-pressure reactor and sealing it, place it in an oven for a solvothermal reaction at a preset temperature and time. S4. After the reaction is complete, the resulting suspension is separated into solid and liquid by centrifugation, the precipitate is collected and dried in a vacuum drying oven. S5. The dried product is subjected to electrochemical reduction treatment to obtain the target high-entropy NiFeCuCoRu hydroxide.
2. The method for preparing high-entropy NiFeCuCoRu hydroxide according to claim 1, characterized in that, In S1, the total molar amount of the nickel salt, iron salt, copper salt, cobalt salt, and ruthenium salt is 1 mmol; the molar amount of the terephthalic acid is 1~4 mmol; the volume of the N,N-dimethylformamide is 1~5 mL; and the concentration of the sodium hydroxide solution is 0.4 mol / L, with a volume of 1~5 mL.
3. The method for preparing high-entropy NiFeCuCoRu hydroxide according to claim 1, characterized in that, In S1, the nickel salt, iron salt, copper salt, cobalt salt, and ruthenium salt are nickel chloride hexahydrate, ferric chloride hexahydrate, copper chloride, cobalt chloride, and ruthenium chloride, respectively, and their molar ratio is 8.5:1:0.1:0.1:0.
3.
4. The method for preparing high-entropy NiFeCuCoRu hydroxide according to claim 1, characterized in that, In S2, the ultrasonic power is 200-400 watts and the ultrasonic time is 5-60 minutes.
5. The method for preparing high-entropy NiFeCuCoRu hydroxide according to claim 1, characterized in that, In S3, the heating rate is 1~10℃ / min, the oven temperature is set to 100~150℃, and the solvothermal reaction time is 12~24 hours.
6. The method for preparing high-entropy NiFeCuCoRu hydroxide according to claim 1, characterized in that, In step S4, the centrifugation speed is 6000~10000 rpm, the centrifugation time is 5~15 minutes, the washing solvent is N,N-dimethylformamide or ethanol, the washing number is 3~6 times, the vacuum drying temperature is 60~100℃, and the time is 6~24h.
7. The method for preparing high-entropy NiFeCuCoRu hydroxide according to claim 1, characterized in that, In step S5, the Chenhua electrochemical workstation is used to perform electrochemical reduction and activation by cyclic voltammetry to obtain the target high-entropy NiFeCuCoRu hydroxide.
8. A high-entropy NiFeCuCoRu hydroxide, characterized in that, It is prepared by the method for preparing high-entropy NiFeCuCoRu hydroxide according to any one of claims 1-7.
9. The high-entropy NiFeCuCoRu hydroxide according to claim 8, characterized in that, The high-entropy NiFeCuCoRu hydroxide has a dense nanoflower structure.
10. The application of the high-entropy NiFeCuCoRu hydroxide according to claim 8 or 9 as a catalyst or electrode material for oxygen evolution at the anode in alkaline water electrolysis for hydrogen production.