Preparation method and application of a self-supporting Ru / Ni-MOF electrocatalyst

Abstract

The application relates to a preparation method of a self-supporting Ru / Ni-MOF electrocatalyst and application thereof, and belongs to the electrocatalyst preparation technology used in the field of hydrogen production by water electrolysis. In the application, a solvent-thermal reaction is firstly adopted to uniformly grow Ni-MOF nanosheets on a conductive substrate, and then an ion exchange strategy is adopted to introduce atomically dispersed Ru into the Ni-MOF structure to obtain a self-supporting Ru / Ni-MOF electrode material. The atomically dispersed Ru can efficiently play a catalytic performance, improve the utilization efficiency of noble metals, and reduce the cost. Meanwhile, the synergistic effect of the Ni and Ru metal sites makes the self-supporting electrode exhibit excellent hydrogen evolution reaction activity, and the application has guiding significance for designing a noble metal and MOF high-performance composite catalytic material.

Description

Technical Field

[0001] This invention pertains to the preparation technology of electrocatalysts used in the field of hydrogen production by water electrolysis, specifically relating to the preparation and application of a self-supporting Ru / Ni-MOF electrocatalyst. Background Technology

[0002] Developing green and clean energy is crucial for alleviating the energy crisis and improving increasingly serious environmental problems. Hydrogen energy, as a zero-carbon, high-energy-density clean energy source, will occupy an important position in the future green energy structure. Water electrolysis for hydrogen production has advantages such as high hydrogen purity and pollution-free reaction, making it one of the most promising hydrogen production technologies. The hydrogen evolution reaction, as one of the half-reactions in water electrolysis for hydrogen production, requires a highly efficient electrocatalyst to lower the reaction energy barrier and reduce energy consumption. Currently, commercially available precious metal Pt-based catalysts are expensive, hindering industrial application. Therefore, it is necessary to seek inexpensive and highly active electrocatalysts to improve hydrogen production efficiency.

[0003] Metal-organic frameworks (MOFs) are a new class of porous crystalline materials with advantages such as tunable structure and large specific surface area. By selecting appropriate metal centers and organic ligand types, they have shown great application potential in energy storage and conversion. The noble metal Ru is relatively inexpensive compared to Pt, but Ru's metal-hydrogen bond strength is similar to Pt's. By atomically dispersing Ru into the MOF framework, the unique advantages of both can be fully utilized, enhancing the activity and stability of the hydrogen evolution reaction and achieving a two-atom synergistic catalysis effect. Simultaneously, atomically dispersed Ru can improve atom utilization efficiency and reduce catalyst production costs. In the electrode preparation process of traditional powder catalysts, the addition of binders can bury some active sites and easily detach from the electrode surface, affecting stability. Growing the catalyst in situ onto the substrate surface to construct a self-supporting electrode can fully expose the active sites, enhance catalyst stability, and is expected to achieve industrial applications. Therefore, uniformly dispersing atomically dispersed Ru in the MOF structure to construct a high-performance self-supporting hydrogen evolution electrode is of significant research importance for achieving high-efficiency hydrogen production. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to construct a self-supporting two-dimensional Ni-MOF nanosheet array and provide a preparation method that utilizes an ion exchange strategy to disperse atomic-level Ru into the MOF structure, thereby obtaining a self-supporting hydrogen evolution electrode with excellent activity and stability.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] A method for preparing a self-supporting Ru / Ni-MOF electrocatalyst, the method comprising the following steps: (1) Cleaning of the nickel foam substrate; (2) The nickel salt and carboxylic acid organic ligand were dissolved in N,N-dimethylformamide DMF and distilled water under stirring. The mixed solution was poured into a high-pressure reactor and the clean nickel foam from step (1) was added. After a certain time of solvothermal reaction under certain temperature conditions, the temperature was lowered to room temperature. The nickel foam on which MOF was grown was taken out, rinsed several times with distilled water and ethanol, and freeze-dried to obtain a two-dimensional Ni-MOF nanosheet array grown on a nickel foam substrate. (3) Ruthenium chloride was added to an alcohol solvent and ultrasonically stirred for 5 minutes to form a uniform solution. Then the solution was transferred to a high-pressure reactor and nickel foam with Ni-MOF growing was placed in it. The reactor was heated at a constant temperature in an oven to carry out ion exchange, so that atomic-level Ru was uniformly dispersed in the MOF structure. After the reaction, the reactor was rinsed multiple times with ethanol and distilled water, and then freeze-dried to obtain self-supporting Ru / Ni-MOF nanomaterials.

[0007] Furthermore, in step (1): the nickel foam is placed in 2M dilute hydrochloric acid solution, distilled water and ethanol respectively for ultrasonic cleaning for 5-10 minutes to remove the oxide layer and organic impurities on the substrate surface.

[0008] Furthermore, the nickel salt mentioned in step (2) is either nickel chloride or nickel nitrate, and the organic ligand is 2,6-naphthalenedicarboxylic acid.

[0009] Preferably, in step (2), the molar ratio of nickel salt to 2,6-naphthalenedicarboxylic acid ligand is 1:1 to 1:3; more specifically, it is 1:1, 1:2, or 1:3.

[0010] In step (2), the volume ratio of DMF to distilled water is 6:1-10:1, and more specifically, 6:1, 8:1 and 10:1.

[0011] The solvothermal reaction temperature in step (2) is 100-160°C, and more specifically 110°C, 130°C and 160°C; the reaction time is 8-16h, and more specifically 8h, 12h and 16h.

[0012] Furthermore, in step (3), the alcohol solvent is either methanol or ethanol.

[0013] Preferably, in step (3), the mass of ruthenium chloride is 0.02g-0.04g, and more specifically, it is 0.02g, 0.03g or 0.04g; the volume of ethanol is 20-40mL, and more specifically, it is 20mL, 30mL or 40mL.

[0014] In step (3), the ion exchange temperature is 60-100°C, and more specifically, it is 70°C, 80°C or 100°C; the reaction time is 10-16h, and more specifically, it is 10h, 12h or 16h.

[0015] This invention also provides an application of a self-supported Ru / Ni-MOF electrocatalyst in the hydrogen evolution reaction. The self-supported Ru / Ni-MOF electrode can be directly used as the working electrode for the hydrogen evolution reaction, exhibiting excellent catalytic activity and long-term stability.

[0016] Beneficial technical effects of the present invention: (1) Compared with the prior art, the preparation method of the present invention is easy to implement, has good reproducibility, and the obtained ultrathin two-dimensional MOF array can fully expose the active sites.

[0017] (2) Atomic Ru is dispersed into the Ni-MOF structure through an ion exchange strategy. This method is simple to operate and conducive to industrial production. In addition, the high dispersion of Ru atoms can improve the utilization efficiency of noble metal atoms and reduce costs.

[0018] (3) The Ru / Ni-MOF electrocatalyst constructed in this invention exhibits a significant improvement in hydrogen evolution catalytic performance due to the synergistic effect between Ni and Ru diatoms. The resulting Ru / Ni-MOF self-supporting nanoarray simplifies the electrode preparation process and can be directly used as the working electrode, avoiding the addition of binders that could bury active sites, thereby increasing long-term stability. Attached Figure Description

[0019] Figure 1 The diffraction patterns of Ni-MOF and Ru / Ni-MOF powders prepared in Example 1 of this invention are shown.

[0020] Figure 2 The images are scanning electron microscope (SEM) images of Ni-MOF and Ru / Ni-MOF prepared in Example 1 of this invention.

[0021] Figure 3 This is an atomic force microscope image of the Ru / Ni-MOF prepared in Example 1 of the present invention.

[0022] Figure 4 This is a transmission electron microscope image of the Ru / Ni-MOF prepared in Example 1 of the present invention.

[0023] Figure 5 The polarization curves of the self-supporting Ni-MOF and Ru / Ni-MOF prepared in Example 1 of this invention as working electrodes for the hydrogen evolution reaction are shown.

[0024] Figure 6This is a long-term stability test diagram of the self-supported Ru / Ni-MOF catalyzed hydrogen evolution reaction prepared in Example 1 of the present invention. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to embodiments, but the scope of protection of the present invention is not limited to the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Example 1

[0026] A method for preparing a self-supporting Ru / Ni-MOF electrocatalyst, the method comprising the following steps: (1) Place the nickel foam with a size of 1.5cm×3.5cm into 2M dilute hydrochloric acid solution, distilled water and ethanol respectively for ultrasonic cleaning for 5 minutes to remove the oxide layer and organic impurities on the surface, and dry it for later use.

[0027] (2) Weigh 0.214 g NiCl2·6H2O and 0.24 g 2,6-naphthalenedicarboxylic acid organic ligands and dissolve them in 24 mL LDM and 3 mL distilled water, then sonicate to dissolve. Place the above mixed solution into a 50 mL reaction vessel, add cleaned nickel foam, and carry out a solvothermal reaction at a constant temperature of 130°C for 12 h. After the reaction, allow it to cool naturally to room temperature. Remove the nickel foam from which the MOF is grown and rinse it several times with distilled water and ethanol to obtain a Ni-MOF nanosheet array grown on a nickel foam substrate. (Appendix) Figure 1 and attached Figure 2 (Figure a) shows the diffraction and scanning electron microscope images of the Ni-MOF powder grown on the surface of nickel foam prepared in Example 1. As can be seen from the figures, the Ni-MOF nanosheets are regularly grown on the surface of nickel foam, exhibiting a two-dimensional nanosheet morphology.

[0028] (3) Weigh 0.03 g of ruthenium chloride and disperse it in 30 mL of ethanol, stirring for 10 min to form a homogeneous solution. Immerse the prepared Ni-MOF in the above solution and transfer it to a 50 mL reaction vessel, heating at 80°C for 12 h. Allow it to cool naturally to room temperature, and wash it several times with distilled water and ethanol to obtain self-supporting Ru / Ni-MOF nanomaterials. (Appendix) Figure 1 and attached Figure 2 (Figure b) shows the powder diffraction and scanning electron microscope images of the self-supporting Ru / Ni-MOF prepared in Example 1, respectively. As can be seen from the figures, the introduction of atomically dispersed Ru did not alter the original structure and morphology of the Ni-MOF. (See attached figures.) Figure 3 This is an atomic force microscope image of the self-supporting Ru / Ni-MOF nanosheets prepared in Example 1. As shown in the figure, the thickness of the Ru / Ni-MOF nanosheets is approximately 4 nm. Figure 4The image shows a transmission electron microscope (TEM) image of the Ru / Ni-MOF prepared in Example 1. As can be seen from the figure, C, O, Ru, and Ni are uniformly distributed on the surface of the nanosheets. Example 2

[0029] A method for preparing a self-supporting Ru / Ni-MOF electrocatalyst, the method comprising the following steps: (1) Place the nickel foam with a size of 1.5cm×3.5cm into 2M dilute hydrochloric acid solution, distilled water and ethanol respectively for ultrasonic cleaning for 5 minutes to remove the oxide layer and organic impurities on the surface, and dry it for later use.

[0030] (2) Weigh 0.262 g Ni(NO3)2·6H2O and 0.24 g 2,6-naphthalenedicarboxylic acid organic ligands and dissolve them in 24 mL LDM and 3 mL distilled water, and sonicate to dissolve them. Put the above mixed solution into a 50 mL reaction vessel, add cleaned nickel foam, and carry out a solvothermal reaction at a constant temperature of 130°C for 12 h. After the reaction, let it cool naturally to room temperature, take out the nickel foam on which MOF is grown, and wash it several times with distilled water and ethanol to obtain a Ni-MOF nanosheet array grown on a nickel foam substrate.

[0031] (3) Weigh 0.03 g of ruthenium chloride and disperse it in 30 mL of ethanol. Stir for 10 min to form a homogeneous solution. Immerse the prepared Ni-MOF in the above solution and transfer it to a 50 mL reaction vessel. Heat at 80°C for 12 h. Cool naturally to room temperature and wash several times with distilled water and ethanol to obtain self-supporting Ru / Ni-MOF nanomaterials. Example 3

[0032] A method for preparing a self-supporting Ru / Ni-MOF electrocatalyst, the method comprising the following steps: (1) Place the nickel foam with a size of 1.5cm×3.5cm into 2M dilute hydrochloric acid solution, distilled water and ethanol respectively for ultrasonic cleaning for 5 minutes to remove the oxide layer and organic impurities on the surface, and dry it for later use.

[0033] (2) Weigh 0.214 g NiCl2·6H2O and 0.24 g 2,6-naphthalenedicarboxylic acid organic ligands and dissolve them in 30 mL LDM and 3 mL distilled water, and sonicate to dissolve them. Put the above mixed solution into a 50 mL reaction vessel, add cleaned nickel foam, and carry out a solvothermal reaction at a constant temperature of 130°C for 12 h. After the reaction, let it cool naturally to room temperature, take out the nickel foam on which MOF is grown, and wash it several times with distilled water and ethanol to obtain a Ni-MOF nanosheet array grown on a nickel foam substrate.

[0034] (3) Weigh 0.03 g of ruthenium chloride and disperse it in 30 mL of ethanol. Stir for 10 min to form a homogeneous solution. Immerse the prepared Ni-MOF in the above solution and transfer it to a 50 mL reaction vessel. Heat at 80°C for 12 h. Cool naturally to room temperature and wash several times with distilled water and ethanol to obtain self-supporting Ru / Ni-MOF nanomaterials. Example 4

[0035] A method for preparing a self-supporting Ru / Ni-MOF electrocatalyst, the method comprising the following steps: (1) Place the nickel foam with a size of 1.5cm×3.5cm into 2M dilute hydrochloric acid solution, distilled water and ethanol respectively for ultrasonic cleaning for 5 minutes to remove the oxide layer and organic impurities on the surface, and dry it for later use.

[0036] (2) Weigh 0.214 g NiCl2·6H2O and 0.24 g 2,6-naphthalenedicarboxylic acid organic ligands and dissolve them in 30 mL LDM and 3 mL distilled water, and sonicate to dissolve them. Put the above mixed solution into a 50 mL reaction vessel, add cleaned nickel foam, and carry out a solvothermal reaction at a constant temperature of 130°C for 12 h. After the reaction, let it cool naturally to room temperature, take out the nickel foam on which MOF is grown, and wash it several times with distilled water and ethanol to obtain a Ni-MOF nanosheet array grown on a nickel foam substrate.

[0037] (3) Weigh 0.03 g of ruthenium chloride and disperse it in 30 mL of methanol. Stir for 10 min to form a homogeneous solution. Immerse the prepared Ni-MOF in the above solution and transfer it to a 50 mL reaction vessel. Heat at 80°C for 12 h. Cool naturally to room temperature and wash several times with distilled water and ethanol to obtain self-supporting Ru / Ni-MOF nanomaterials. Example 5

[0038] A method for preparing a self-supporting Ru / Ni-MOF electrocatalyst, the method comprising the following steps: (1) Place the nickel foam with a size of 1.5cm×3.5cm into 2M dilute hydrochloric acid solution, distilled water and ethanol respectively for ultrasonic cleaning for 5 minutes to remove the oxide layer and organic impurities on the surface, and dry it for later use.

[0039] (2) Weigh 0.214 g NiCl2·6H2O and 0.24 g 2,6-naphthalenedicarboxylic acid organic ligands and dissolve them in 30 mL LDM and 3 mL distilled water, and sonicate to dissolve them. Put the above mixed solution into a 50 mL reaction vessel, add cleaned nickel foam, and carry out a solvothermal reaction at a constant temperature of 130°C for 12 h. After the reaction, let it cool naturally to room temperature, take out the nickel foam on which MOF is grown, and wash it several times with distilled water and ethanol to obtain a Ni-MOF nanosheet array grown on a nickel foam substrate.

[0040] (3) Weigh 0.04 g of ruthenium chloride and disperse it in 30 mL of ethanol. Stir for 10 min to form a homogeneous solution. Immerse the prepared Ni-MOF in the above solution and transfer it to a 50 mL reaction vessel. Heat at 80°C for 12 h. Cool naturally to room temperature and wash several times with distilled water and ethanol to obtain self-supporting Ru / Ni-MOF nanomaterials. Example 6

[0041] A method for preparing a self-supporting Ru / Ni-MOF electrocatalyst, the method comprising the following steps: (1) Place the nickel foam with a size of 1.5cm×3.5cm into 2M dilute hydrochloric acid solution, distilled water and ethanol respectively for ultrasonic cleaning for 10 minutes to remove the oxide layer and organic impurities on the surface, and dry it for later use.

[0042] (2) Weigh 0.214 g NiCl2·6H2O and 0.24 g 2,6-naphthalenedicarboxylic acid organic ligands and dissolve them in 18 mL LDM and 3 mL distilled water, and sonicate to dissolve them. Put the above mixed solution into a 50 mL reaction vessel, add cleaned nickel foam, and carry out a solvothermal reaction at a constant temperature of 160°C for 8 h. After the reaction, let it cool naturally to room temperature, take out the nickel foam on which MOF is grown, and wash it several times with distilled water and ethanol to obtain a Ni-MOF nanosheet array grown on a nickel foam substrate.

[0043] (3) Weigh 0.02 g of ruthenium chloride and disperse it in 40 mL of methanol. Stir for 10 min to form a homogeneous solution. Immerse the prepared Ni-MOF in the above solution and transfer it to a 50 mL reaction vessel. Heat at a constant temperature of 60°C for 16 h. Cool naturally to room temperature and wash several times with distilled water and ethanol to obtain self-supporting Ru / Ni-MOF nanomaterials. Example 7

[0044] A method for preparing a self-supporting Ru / Ni-MOF electrocatalyst, the method comprising the following steps: (1) Place the nickel foam with a size of 1.5cm×3.5cm into 2M dilute hydrochloric acid solution, distilled water and ethanol respectively for ultrasonic cleaning for 5 minutes to remove the oxide layer and organic impurities on the surface, and dry it for later use.

[0045] (2) Weigh 0.214 g NiCl2·6H2O and 0.24 g 2,6-naphthalenedicarboxylic acid organic ligands and dissolve them in 28 mL LDM and 3 mL distilled water, and sonicate to dissolve them. Put the above mixed solution into a 50 mL reaction vessel, add cleaned nickel foam, and carry out a solvothermal reaction at a constant temperature of 110°C for 10 h. After the reaction, let it cool naturally to room temperature, take out the nickel foam on which MOF is grown, and wash it several times with distilled water and ethanol to obtain a Ni-MOF nanosheet array grown on a nickel foam substrate.

[0046] (3) Weigh 0.03 g of ruthenium chloride and disperse it in 20 mL of methanol. Stir for 10 min to form a homogeneous solution. Immerse the prepared Ni-MOF in the above solution and transfer it to a 50 mL reaction vessel. Heat at 100°C for 10 h. Cool naturally to room temperature and wash several times with distilled water and ethanol to obtain self-supported Ru / Ni-MOF nanomaterials. Example 8

[0047] A method for preparing a self-supporting Ru / Ni-MOF electrocatalyst, the method comprising the following steps: (1) Place the nickel foam with a size of 1.5cm×3.5cm into 2M dilute hydrochloric acid solution, distilled water and ethanol respectively for ultrasonic cleaning for 8 minutes to remove the oxide layer and organic impurities on the surface, and dry it for later use.

[0048] (2) Weigh 0.214 g NiCl2·6H2O and 0.24 g 2,6-naphthalenedicarboxylic acid organic ligands and dissolve them in 20 mL LDM and 3 mL distilled water, and sonicate to dissolve them. Put the above mixed solution into a 50 mL reaction vessel, add cleaned nickel foam, and carry out a solvothermal reaction at a constant temperature of 100°C for 16 h. After the reaction, let it cool naturally to room temperature, take out the nickel foam on which MOF is grown, and wash it several times with distilled water and ethanol to obtain a Ni-MOF nanosheet array grown on a nickel foam substrate.

[0049] (3) Weigh 0.04 g of ruthenium chloride and disperse it in 30 mL of ethanol. Stir for 10 min to form a homogeneous solution. Immerse the prepared Ni-MOF in the above solution and transfer it to a 50 mL reaction vessel. Heat at a constant temperature of 70°C for 14 h. Cool naturally to room temperature and wash several times with distilled water and ethanol to obtain self-supporting Ru / Ni-MOF nanomaterials. Example 9

[0050] Application of the self-supporting Ru / Ni-MOF nanomaterials prepared in Example 1 above in water electrolysis.

[0051] A three-electrode system was used, with the self-supporting Ru / Ni-MOF electrode prepared in Example 1 directly serving as the working electrode for the hydrogen evolution reaction, and its electrochemical performance was tested. Figure 5 Linear voltammetry tests showed that Ru / Ni-MOF possesses excellent electrocatalytic hydrogen evolution activity. (See attached image) Figure 6 This indicates that the catalyst has good long-term stability.

[0052] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a self-supporting Ru / Ni-MOF electrocatalyst, characterized in that, The method includes the following steps: Step 1: Cut and clean the nickel foam substrate; Step 2: Dissolve one of nickel chloride or nickel nitrate and the carboxylic acid organic ligand 2,6-naphthalenedicarboxylic acid in N,N-dimethylformamide (DMF) and distilled water under ultrasonic stirring. Place the well-mixed solution into a high-pressure reactor and add the cleaned and dried nickel foam from Step 1. Seal and carry out a solvothermal reaction. After reacting at a certain temperature for a set time, allow it to cool naturally to room temperature. Wash the removed nickel foam with distilled water and ethanol respectively, and freeze-dry to obtain a regular two-dimensional Ni-MOF nanosheet array grown on the nickel foam. Step 3: Add ruthenium chloride to the alcohol solvent and stir thoroughly to form a homogeneous solution. Then, transfer the solution to the reactor and immerse the nickel foam on which Ni-MOF is grown into the solution. Heat at a constant temperature to carry out ion exchange. After the reaction, wash the self-supporting composite material multiple times with ethanol and distilled water to obtain the self-supporting Ru / Ni-MOF electrocatalyst. In step 2, the molar ratio of nickel ions to organic ligands is 1:1 to 1:3; the solvothermal reaction temperature is 100-160 °C; and the reaction time is 8-16 h. In step 3, the mass of ruthenium chloride is 0.02 g-0.04 g, the volume of alcohol solvent is 20-40 mL, the ion exchange reaction temperature is 60-100 ℃, and the reaction time is 10-16 h.

2. The method for preparing the self-supporting Ru / Ni-MOF electrocatalyst according to claim 1, characterized in that, In step 1: The nickel foam is placed in 2 M dilute hydrochloric acid solution, distilled water and ethanol in turn for ultrasonic cleaning for 5-10 minutes each to remove the oxide layer and organic impurities on the surface.

3. The method for preparing the self-supporting Ru / Ni-MOF electrocatalyst according to claim 1, characterized in that, In step 2, the volume ratio of DMF to distilled water is 6:1-10:

1.

4. The method for preparing the self-supporting Ru / Ni-MOF electrocatalyst according to claim 1, characterized in that, In step 3, the alcohol solvent is either methanol or ethanol.

5. A self-supporting Ru / Ni-MOF electrocatalyst, characterized in that, It is prepared by the method described in any one of claims 1-4.

6. The application of the self-supporting Ru / Ni-MOF electrocatalyst according to claim 5 in the water electrolysis reaction.

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