Preparation method and application of organic ligand modified Ru atom doped NiFe-LDH material

Abstract

The invention relates to a preparation method and application of an organic ligand modified Ru atom doped NiFe-LDH material. The preparation method comprises the following steps: firstly, uniformly growing a NiFe-LDH nanosheet array on a foamed nickel substrate by adopting a hydrothermal method, and uniformly dispersing Ru atoms in a NiFe-LDH structure through an ion exchange strategy; and then, an organic ligand is introduced by a solvothermal method for modification, so that the NiFe-LDH-coated Ru-BDT composite electro-catalytic material is obtained. The organic ligand effectively inhibits dissolution of Ru atoms under high voltage through coordination, and compared with the prior art, the bifunctional catalytic activity and stability of the catalyst under high current density can be remarkably improved. The preparation method disclosed by the invention is simple in process and good in repeatability, can efficiently utilize noble metal materials and reduce the cost, and has the application potential of industrial hydrogen production by water electrolysis.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen production by water electrolysis, and particularly relates to a preparation method of an organic ligand modified Ru atom doped NiFe-LDH material and application thereof in water electrolysis. BACKGROUND

[0002] Hydrogen energy has advantages such as high energy density and zero carbon dioxide emission, and can become a solution to promote low-carbon development in multiple industries. Water electrolysis for hydrogen production has developed into one of the most promising sustainable hydrogen production technologies due to its characteristics such as few side reactions and green economy.

[0003] NiFe-LDH materials are considered as a kind of electrocatalyst with great potential due to their unique layered structure. In order to meet the needs of actual industrial application, the catalytic performance and stability thereof still need to be further optimized and improved.

[0004] The introduction of noble metals (such as Ru, Pt, Ir) can improve the activity of NiFe-LDH materials. However, the traditional heteroatom doping method will cause the agglomeration of noble metal particles, and the utilization rate is low. Moreover, the noble metal will gradually dissolve at high voltage, resulting in poor stability, and it is difficult to realize industrial application. Therefore, reducing the noble metal loading, and improving the bifunctional activity and stability of the noble metal doped NiFe-LDH are key scientific problems to be solved for industrial water electrolysis. SUMMARY

[0005] In view of the above problems, the application provides a preparation method of an organic ligand modified Ru atom doped NiFe-LDH material. NiFe-LDH nanosheets are uniformly grown on a foam nickel substrate by a hydrothermal method. Ru atoms are uniformly dispersed in the LDH structure by an ion exchange strategy, and a thiol organic ligand is introduced for modification, so as to obtain a NiFe-LDH@Ru-BDT composite material with bifunctional catalytic activity and excellent stability. In order to achieve the above purpose, the following technical solutions are adopted.

[0006] The preparation method of the organic ligand modified Ru atom doped NiFe-LDH material comprises the following steps:

[0007] (1) Pretreatment of the foam nickel substrate, the foam nickel substrate is cut and cleaned, and the surface oxide layer and organic matter are removed by ultrasonic treatment with hydrochloric acid, deionized water and anhydrous ethanol. After pretreatment, the foam nickel substrate is dried for standby use;

[0008] (2) Dissolve the nickel salt, iron salt, ammonium fluoride and urea in deionized water under ultrasonic stirring, put the uniformly mixed solution into a high-pressure reaction kettle, and add the foam nickel dried after pretreatment in step (1), seal and perform solvothermal reaction, after reaction at a certain temperature for a certain time, naturally cool to room temperature, and then wash and dry the extracted foam nickel with deionized water and ethanol in sequence to obtain regular NiFe-LDH nanosheet arrays grown on the foam nickel;

[0009] (3) Add ruthenium chloride to a mixed solvent of deionized water and anhydrous ethanol, form a uniformly mixed solution by ultrasonic stirring for 5 minutes, transfer to a reaction kettle, and immerse the foam nickel on which NiFe-LDH is grown obtained in step 2 in the mixed solution of this step, place in an oven for constant temperature heating to perform ion exchange, after reaction, wash the sample with deionized water and anhydrous ethanol for multiple times, and dry to obtain a NiFe-LDH@Ru electrocatalyst;

[0010] (4) Dissolve benzene-1,2-dithiol (BDT) organic ligand in N,N-dimethylformamide (DMF) organic solvent under ultrasonic stirring, put the uniformly mixed solution into a high-pressure reaction kettle, and add the NiFe-LDH@Ru dried after treatment in step 3, seal and perform solvothermal reaction, after reaction at a certain temperature for a certain time, naturally cool to room temperature, and then wash the material with ethanol and deionized water for multiple times to obtain a NiFe-LDH@Ru-BDT nanocomposite material;

[0011] In step 3, the mass of ruthenium chloride is 18-20 mg; in step 4, the mass of benzene-1,2-dithiol is 7-8 mg.

[0012] Further, in step (1), the foam nickel is sequentially placed in 2M dilute hydrochloric acid solution, deionized water and anhydrous ethanol, and ultrasonically cleaned for 10-15 minutes to remove the surface oxide layer and organic impurities.

[0013] Further, in step (2), the nickel salt is one of nickel chloride or nickel nitrate, and the iron salt is one of iron chloride or iron nitrate.

[0014] Preferably, in step (2), the molar ratio of the nickel salt to the iron salt is 8:3-10:3, and is further specifically selected as 8:3, 9:3 or 10:3.

[0015] Further, in step (2), the molar ratio of ammonium fluoride to urea is 5:2-5:3.

[0016] Further, in step (2), the solvothermal reaction temperature is 100-120℃, and is further specifically selected as 100℃, 110℃ or 120℃; the reaction time is 10-12h, and is further specifically selected as 10h, 11h or 12h.

[0017] Further, the solvent in step (3) is a mixture of deionized water and anhydrous ethanol 20-40ml, and further preferably 30ml.

[0018] Preferably, the mass of ruthenium chloride in step (3) is 18-20mg, and further specifically selected as 18mg, 19mg or 20mg; the volume ratio of deionized water to anhydrous ethanol in the solvent is 1:1, and specifically, the volume of deionized water is 15ml, and the volume of anhydrous ethanol is 15ml.

[0019] The ion exchange temperature in step (3) is 80-100℃, and further specifically selected as 80℃, 90℃ or 100℃; the reaction time is 8-12h, and further specifically selected as 8h, 10h or 12h.

[0020] Further, the volume of the solvent DMF in step 4 is 20-40ml.

[0021] Further, the hydrothermal reaction temperature in step 4 is 100-120℃, and further specifically selected as 100℃, 110℃ and 120℃; the reaction time is 10-12 hours, and further specifically selected as 8h, 10h or 12h.

[0022] The application also provides a use of the NiFe-LDH@Ru-BDT electrocatalyst in electrolytic water.

[0023] The application has the beneficial technical effects:

[0024] The NiFe-LDH@Ru-BDT composite material provided by the application has a simple preparation process and good reproducibility, and is easy to mass industrial production; the Ru atom is ingeniously introduced to reshape the electron arrangement of NiFe-LDH, and the electron cloud density and energy level distribution of the active site are precisely controlled, so that the activation energy barrier of the catalytic reaction is significantly reduced; at the same time, through the strong interaction between the mercaptan ligand and the metal atom, the dissolution and agglomeration of Ru atoms in the industrial high current density environment are effectively inhibited, effectively solving the stability problem of noble metal catalysts in industrialization; the traditional preparation process is abandoned in technology, and a composite process of hydrothermal method combined with ion exchange and solvothermal modification is adopted, which greatly improves the atomic utilization rate of noble metals. In terms of performance, it exhibits excellent bifunctional electrocatalytic performance under high current density; corresponding to 500mA·cm -2The HER overpotential is as low as -150 mV and the OER overpotential is as low as 270 mV at a current density, which is far superior to mainstream commercial noble metal catalysts Pt / C and RuO2; in long-time large-current density tests, it also shows significant stability, which provides solid technical support for industrial large-scale electrolytic water hydrogen production. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The scanning electron microscope images of the NiFe-LDH@Ru-BDT, NiFe-LDH@Ru and NiFe-LDH prepared in Example 1 of the application.

[0026] Figure 2 The powder diffraction images of the NiFe-LDH@Ru-BDT, NiFe-LDH@Ru and NiFe-LDH prepared in Example 1 of the application.

[0027] Figure 3 The atomic force microscope images of the NiFe-LDH prepared in Example 1 of the application.

[0028] Figure 4 The transmission electron microscope images of the NiFe-LDH@Ru-BDT prepared in Example 1 of the application.

[0029] Figure 5 The polarization curve images of the NiFe-LDH@Ru-BDT prepared in Example 1 of the application as a HER working electrode, and the long-time stability test images of the NiFe-LDH@Ru-BDT catalytic hydrogen evolution.

[0030] Figure 6 The polarization curve images of the NiFe-LDH@Ru-BDT prepared in Example 1 of the application as an OER working electrode, and the long-time stability test images of the NiFe-LDH@Ru-BDT catalytic oxygen evolution.

[0031] Figure 7 The scanning electron microscope images of the materials prepared in the comparative example of the application. DETAILED DESCRIPTION

[0032] The application will be further described in conjunction with the examples below, but the scope of protection of the application is not limited to the examples. Based on the examples in the application, all other examples obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the application.

[0033] Example 1:

[0034] A preparation method of an organic ligand modified Ru atom doped NiFe-LDH material, the method comprising the following steps:

[0035] (1) The foamed nickel (1.5 cm x 6 cm) was sequentially cleaned with 2M dilute hydrochloric acid solution, deionized water and anhydrous ethanol by ultrasonic cleaning for 15 minutes, and the surface oxide layer and organic impurities were removed. After drying, it was used as a substrate.

[0036] (2) 0.6543 g (2.25 mmol) of Ni(NO3)2·6H2O, 0.2727 g (0.675 mmol) of Fe(NO3)3·9H2O, 0.14816 g (4 mmol) of NH4F and 0.6004 g (10 mmol) of urea were dissolved in 40 mL of deionized water, and the mixed solution was transferred to a 50 mL reaction kettle and then to an autoclave. The pretreated foamed nickel in (1) was vertically added, and the solvothermal reaction was carried out at 120°C for 10 h. After the reaction, it was naturally cooled to room temperature, and the foamed nickel substrate with NiFe-LDH grown thereon was taken out and washed with deionized water and anhydrous ethanol several times to obtain the NiFe-LDH nanosheet array grown on the foamed nickel substrate. Figure 1 and Figure 2 The scanning electron microscope image and powder diffraction pattern of the NiFe-LDH grown on the surface of the foamed nickel prepared in this example 1 are shown in the accompanying drawings. As can be seen from the drawings, the NiFe-LDH nanosheets are regularly grown on the surface of the foamed nickel, showing a regular nanosheet morphology.

[0037] (3) 18 mg of ruthenium chloride was dispersed in 30 mL of a mixed solution of deionized water and anhydrous ethanol, and stirred for 10 min to form a uniform solution. The prepared NiFe-LDH was immersed in the above solution and transferred to a 50 mL reaction kettle, and heated at 80°C for 4 h. It was naturally cooled to room temperature and washed with deionized water and ethanol several times to obtain the NiFe-LDH@Ru nanomaterial. The scanning electron microscope image and powder diffraction pattern of the NiFe-LDH grown on the surface of the foamed nickel prepared in this example 1 are shown in the accompanying drawings. As can be seen from the drawings, the NiFe-LDH nanosheets are regularly grown on the surface of the foamed nickel, showing a regular nanosheet morphology. As can be seen from the drawings, the introduction of Ru slightly changes the original structure and morphology of the NiFe-LDH. Figure 1 and Figure 2 The scanning electron microscope image and powder diffraction pattern of the NiFe-LDH grown on the surface of the foamed nickel prepared in this example 1 are shown in the accompanying drawings. As can be seen from the drawings, the NiFe-LDH nanosheets are regularly grown on the surface of the foamed nickel, showing a regular nanosheet morphology. As can be seen from the drawings, the introduction of Ru slightly changes the original structure and morphology of the NiFe-LDH. Figure 3 The atomic force microscope image of the NiFe-LDH prepared in this example 1 is shown in the accompanying drawings. As can be seen from the drawings, the thickness of the NiFe-LDH@Ru nanosheet is about 4 nm. Figure 4 The transmission electron microscope image of the NiFe-LDH@Ru prepared in this example 1 is shown in the accompanying drawings. As can be seen from the drawings, the elements Ni, Fe, Ru and O are uniformly distributed on the surface of the nanosheet.

[0038] (4) 7 mg of benzene dithiol (0.05 mmol) was weighed and dispersed in 30 mL of DMF, and stirred for 10 min to form a uniform solution. The prepared NiFe-LDH@Ru was immersed in the above solution and transferred to a 50 mL reaction kettle, and heated at 120°C for 10 h. It was naturally cooled to room temperature, and washed with deionized water and ethanol several times to obtain the NiFe-LDH@Ru-BDT nanomaterial. Appendix Figure 1 and Appendix Figure 2 The scanning electron microscope image and powder diffraction pattern of the NiFe-LDH@Ru-BDT prepared in Example 1 are shown.

[0039] Example 2:

[0040] A method for preparing an organic ligand modified Ru atom doped NiFe-LDH material, the method comprising the following steps:

[0041] (1) The foam nickel (1.5 cm x 6 cm) was sequentially cleaned with 2M dilute hydrochloric acid solution, deionized water and anhydrous ethanol for 15 minutes, and the surface oxide layer and organic impurities were removed. After drying, it was ready for use.

[0042] (2) 1.188 g of NiCl2·6H2O, 0.45 g of FeCl3·6H2O, 0.14816 g (4 mmol) of NH4F and 0.6004 g (10 mmol) of urea were dissolved in 40 mL of deionized water, and the mixed solution was filled and stirred ultrasonically. After ultrasonic treatment, it was loaded into a 50 mL reaction kettle and transferred to a high-pressure kettle. The pretreated foam nickel in (1) was vertically added, and the solvothermal reaction was carried out at 120°C for 10 h. After the reaction, it was naturally cooled to room temperature, and the foam nickel grown with NiFe-LDH was taken out and washed with deionized water and anhydrous ethanol several times to obtain a NiFe-LDH nanosheet array grown on a foam nickel substrate.

[0043] (3) 18 mg of ruthenium chloride was weighed and dispersed in 30 mL of a mixed solution of deionized water and anhydrous ethanol, and stirred for 10 min to form a uniform solution. The prepared NiFe-LDH was immersed in the above solution and transferred to a 50 mL reaction kettle, and heated at 80°C for 4 h. It was naturally cooled to room temperature, and washed with deionized water and ethanol several times to obtain the -NiFe-LDH@Ru nanomaterial.

[0044] (4) 7 mg of benzene dithiol (0.05 mmol) was weighed and dispersed in 30 mL of DMF, and stirred for 10 min to form a uniform solution. The prepared NiFe-LDH@Ru was immersed in the above solution and transferred to a 50 mL reaction kettle, and heated at 120°C for 10 h. It was naturally cooled to room temperature, and washed with deionized water and ethanol several times to obtain the NiFe-LDH@Ru-BDT nanomaterial.

[0045] Example 3:

[0046] A method for preparing an organic ligand modified Ru atom doped NiFe-LDH material, the method comprising the following steps:

[0047] (1) Foam nickel (1.5 cm x 6 cm) was sequentially cleaned with 2M dilute hydrochloric acid solution, deionized water and anhydrous ethanol for 15 minutes, and the surface oxide layer and organic impurities were removed. After drying, it was used as a substrate.

[0048] (2) Ni(NO3)2·6H2O 0.6543g (2.25mmol), Fe(NO3)3·9H2O 0.2727g (0.675mmol), NH4F 0.14816g (4mmol) and urea 0.6004g (10mmol) were dissolved in 40mL deionized water, and the mixed solution was filled with sufficient stirring and ultrasonic. After ultrasonic, it was transferred to a 50mL reaction kettle and transferred to a high pressure kettle. The pretreated foam nickel in (1) was vertically added, and the solvothermal reaction was carried out at 120℃ constant temperature for 10h. After reaction, it was naturally cooled to room temperature, and the foam nickel substrate with NiFe-LDH growth was taken out and washed with deionized water and anhydrous ethanol several times to obtain NiFe-LDH nanosheet array grown on the foam nickel substrate.

[0049] (3) 19mg of ruthenium chloride was dispersed in 30mL of a mixture of deionized water and anhydrous ethanol, and stirred for 10min to form a uniform solution. The prepared NiFe-LDH was immersed in the above solution and transferred to a 50mL reaction kettle, and heated at 80℃ constant temperature for 4h. Naturally cooled to room temperature, washed with deionized water and ethanol several times to obtain NiFe-LDH@Ru nanomaterial.

[0050] (4) 7mg of benzenedithiol (0.05mmol) was dispersed in 30mL of DMF, and stirred for 10min to form a uniform solution. The prepared NiFe-LDH@Ru was immersed in the above solution and transferred to a 50mL reaction kettle, and heated at 120℃ constant temperature for 10h. Naturally cooled to room temperature, washed with deionized water and ethanol several times to obtain NiFe-LDH@Ru-BDT nanomaterial.

[0051] Example 4:

[0052] A method for preparing an organic ligand modified Ru atom doped NiFe-LDH material, the method comprising the following steps:

[0053] (1) Foam nickel (1.5 cm x 6 cm) was sequentially cleaned with 2M dilute hydrochloric acid solution, deionized water and anhydrous ethanol for 15 minutes, and the surface oxide layer and organic impurities were removed. After drying, it was used as a substrate.

[0054] (2) Weigh 0.6543 g (2.25 mmol) of Ni(NO3)2·6H2O, 0.2727 g (0.675 mmol) of Fe(NO3)3·9H2O, 0.14816 g (4 mmol) of NH4F and 0.6004 g (10 mmol) of urea into 40 mL of deionized water, and after ultrasonic stirring of the mixed solution, transfer it to a 50 mL reaction kettle and move it to a high-pressure kettle. Vertically add the pretreated foam nickel in (1) to the reaction kettle, and perform a solvothermal reaction at 120°C for 10 h under constant temperature conditions. After the reaction, naturally cool to room temperature, and take out the foam nickel with NiFe-LDH growth, and wash it with deionized water and anhydrous ethanol several times in sequence to obtain a NiFe-LDH nanosheet array grown on a foam nickel substrate.

[0055] (3) Weigh 20 mg of ruthenium chloride and disperse it into 30 mL of a mixed solution of deionized water and anhydrous ethanol, and stir for 10 min to form a uniform solution. Immerse the prepared NiFe-LDH into the above solution, and transfer it to a 50 mL reaction kettle, and heat it at a constant temperature of 80°C for 4 h. Naturally cool to room temperature, and wash it with deionized water and ethanol several times to obtain a -NiFe-LDH@Ru nanomaterial.

[0056] (4) Weigh 7 mg (0.05 mmol) of benzene dithiol and disperse it into 30 mL of DMF, and stir for 10 min to form a uniform solution. Immerse the prepared NiFe-LDH@Ru into the above solution, and transfer it to a 50 mL reaction kettle, and heat it at a constant temperature of 120°C for 10 h. Naturally cool to room temperature, and wash it with deionized water and ethanol several times to obtain a NiFe-LDH@Ru-BDT nanomaterial.

[0057] Example 5:

[0058] A method for preparing an organic ligand modified Ru atom doped NiFe-LDH material, the method comprising the following steps:

[0059] (1) Ultrasonically wash foam nickel (1.5 cm x 6 cm) with 2M dilute hydrochloric acid solution, deionized water and anhydrous ethanol for 15 min in sequence, remove the surface oxide layer and organic impurities, and dry for standby use.

[0060] (2) Take Ni(NO3)2·6H2O 0.6543g (2.25mmol), Fe(NO3)3·9H2O 0.2727g (0.675mmol), NH4F 0.14816g (4mmol) and urea 0.6004g (10mmol) dissolved in 40mL deionized water, after ultrasonic stirring, the mixed solution was loaded into a 50mL reactor and transferred to an autoclave, and the pretreated foam nickel in (1) was vertically added, and the solvothermal reaction was carried out at 120℃ for 10h. After reaction, natural cooling to room temperature, the foam nickel substrate with NiFe-LDH nanosheet array was taken out and washed with deionized water and anhydrous ethanol for several times.

[0061] (3) Take 18mg ruthenium chloride and disperse it in 30mL deionized water and anhydrous ethanol mixed solution, stir for 10min to form a uniform solution. The prepared NiFe-LDH was immersed in the above solution and transferred to a 50mL reactor, heated at 80℃ for 4h. Natural cooling to room temperature, washed with deionized water and ethanol for several times, obtained -NiFe-LDH@Ru nanomaterials.

[0062] (4) Take benzene dithiol 14mg (0.1mmol) and disperse it in 30mL DMF, stir for 10min to form a uniform solution. The prepared NiFe-LDH@Ru was immersed in the above solution and transferred to a 50mL reactor, heated at 120℃ for 10h. Natural cooling to room temperature, washed with deionized water and ethanol for several times, obtained NiFe-LDH@Ru-BDT nanomaterials.

[0063] Example 6:

[0064] Application of the NiFe-LDH@Ru-BDT material prepared in the above example 1 in electrolytic water.

[0065] Using a three-electrode system, the NiFe-LDH@Ru-BDT electrode prepared in example 1 was directly used as the working electrode for hydrogen evolution reaction and oxygen evolution reaction, and the electrochemical performance test was carried out. Figure 5 Linear voltammetry test and stability test showed that NiFe-LDH@Ru-BDT had excellent electrocatalytic hydrogen evolution activity and good long-term stability. Figure 6 Linear voltammetry test and stability test showed that NiFe-LDH@Ru-BDT had excellent electrocatalytic oxygen evolution activity and good long-term stability.

[0066] Comparative example 1:

[0067] This comparative example proposes a method for preparing a NiFe-LDH electrocatalyst. The steps are essentially the same as those in Example 1, except that the amount of ammonium fluoride is adjusted to explore its effect on the material morphology. The specific steps are as follows:

[0068] (1) Nickel foam (1.5 cm × 6 cm) was ultrasonically cleaned with 2 M dilute hydrochloric acid solution, deionized water, and anhydrous ethanol for 15 minutes in sequence to remove the surface oxide layer and organic impurities, and then dried for later use.

[0069] (2) Weigh 0.6543 g (2.25 mmol) of Ni(NO3)2·6H2O, 0.2727 g (0.675 mmol) of Fe(NO3)3·9H2O, 0.1111 g (3 mmol) of NH4F, and 0.6004 g (10 mmol) of urea and dissolve them in 40 mL of deionized water. After thorough stirring and ultrasonic treatment, the mixed solution is placed in a 50 mL reactor and transferred to an autoclave. The nickel foam pretreated in (1) is added vertically and the solvent thermal reaction is carried out at a constant temperature of 120°C for 10 h. After the reaction, the mixture is cooled naturally to room temperature. The nickel foam on which NiFe-LDH is grown is taken out and rinsed with deionized water and anhydrous ethanol several times in sequence to obtain a NiFe-LDH nanosheet array grown on the nickel foam substrate.

[0070] By scanning electron microscopy Figure 7 As shown in (a), the microstructure of the NiFe-LDH material prepared in this comparative example has changed significantly: unlike the regular nanosheet array in Example 1, the material forms a fibrous structure, the fibers are intertwined and entangled, showing a network-like morphology, and the active site electron cloud is unevenly distributed, resulting in poor electrochemical performance. This morphological difference indicates that the amount of ammonium fluoride has a key regulatory effect on the growth orientation and crystallization behavior of NiFe-LDH. The reduction in the amount of ammonium fluoride will destroy the layer growth dynamics of NiFe-LDH, resulting in the morphology changing from regular nanosheets to disordered fiber networks. This result further highlights the importance of optimizing process parameters such as the amount of ammonium fluoride on the material structure and performance in Example 1 of the present invention.

[0071] Comparative Example 2:

[0072] This comparative example proposes a method for preparing Ru-doped NiFe-LDH materials. The steps are basically the same as those in Example 1, but the amount of Ru introduced is increased to 25 mg to explore the effect of high Ru loading on the material structure. The specific steps are as follows:

[0073] (1) Nickel foam (1.5 cm × 6 cm) was ultrasonically cleaned with 2 M dilute hydrochloric acid solution, deionized water, and anhydrous ethanol for 15 minutes in sequence to remove the surface oxide layer and organic impurities, and then dried for later use.

[0074] (2) Weigh 0.6543 g (2.25 mmol) of Ni(NO3)2·6H2O, 0.2727 g (0.675 mmol) of Fe(NO3)3·9H2O, 0.14816 g (4 mmol) of NH4F, and 0.6004 g (10 mmol) of urea and dissolve them in 40 mL of deionized water. After thorough stirring and ultrasonication, the mixed solution is placed in a 50 mL reactor and transferred to an autoclave. The nickel foam pretreated in (1) is added vertically and the solvent thermal reaction is carried out at a constant temperature of 120°C for 10 h. After the reaction, the mixture is cooled naturally to room temperature. The nickel foam on which NiFe-LDH is grown is taken out and rinsed with deionized water and anhydrous ethanol several times in sequence to obtain a NiFe-LDH nanosheet array grown on the nickel foam substrate.

[0075] (3) Weigh 25 mg of ruthenium chloride and disperse it in a 30 mL mixture of deionized water and anhydrous ethanol. Stir for 10 min to form a uniform solution. Immerse the prepared NiFe-LDH in the above solution and transfer it to a 50 mL reactor. Heat it at 80°C for 4 h. Cool it naturally to room temperature and rinse it with deionized water and ethanol several times to obtain the NiFe-LDH@Ru nanomaterial.

[0076] Scanning electron microscopy as shown in the attached Figure 7 As shown in (b), the microstructure of the NiFe-LDH@Ru material prepared in this comparative example has undergone significant changes. Unlike the regular nanosheet array in Example 1, after increasing the Ru loading, the original layered structure of NiFe-LDH is completely destroyed, the nanosheet morphology disappears, and is replaced by a disordered aggregation state with severe surface corrosion and structural collapse; this indicates that the excess Ru has a strong etching effect on the NiFe-LDH skeleton during the ion exchange process, resulting in the loss of material structural stability and its electrochemical performance deteriorating accordingly; in contrast, the optimized Ru loading (18-20 mg) of the present invention works synergistically with the organic ligand modification, which can not only enhance the catalytic activity but also maintain the stability of the material structure, further verifying the scientific nature and superiority of the technical solution of the present invention.

[0077] Comparative Example 3:

[0078] This comparative example proposes a method for preparing Ru-doped NiFe-LDH materials modified with organic ligands. The steps are essentially the same as those in Example 1, but the amount of benzenedithiol (BDT) is increased from 0.05 mmol to 0.1 mmol to explore the effect of excess organic ligand on the material morphology. The specific steps are as follows:

[0079] (1) Nickel foam (1.5 cm × 6 cm) was ultrasonically cleaned with 2 M dilute hydrochloric acid solution, deionized water, and anhydrous ethanol for 15 minutes in sequence to remove the surface oxide layer and organic impurities, and then dried for later use.

[0080] (2) Weigh 0.6543 g (2.25 mmol) of Ni(NO3)2·6H2O, 0.2727 g (0.675 mmol) of Fe(NO3)3·9H2O, 0.14816 g (4 mmol) of NH4F, and 0.6004 g (10 mmol) of urea and dissolve them in 40 mL of deionized water. After thorough stirring and ultrasonication, the mixed solution is placed in a 50 mL reactor and transferred to an autoclave. The nickel foam pretreated in (1) is added vertically and the solvent thermal reaction is carried out at a constant temperature of 120°C for 10 h. After the reaction, the mixture is cooled naturally to room temperature. The nickel foam on which NiFe-LDH is grown is taken out and rinsed with deionized water and anhydrous ethanol several times in sequence to obtain a NiFe-LDH nanosheet array grown on the nickel foam substrate.

[0081] (3) Weigh 18 mg of ruthenium chloride and disperse it in a 30 mL mixed solution of deionized water and anhydrous ethanol, stir for 10 min to form a uniform solution. Immerse the prepared NiFe-LDH in the above solution and transfer it to a 50 mL reactor, and heat it at a constant temperature of 80 ° C for 4 h. Cool it naturally to room temperature, wash it with deionized water and ethanol several times, and obtain NiFe-LDH@Ru nanomaterials. (4) Weigh 14 mg (0.1 mmol) of benzenedithiol and disperse it in 30 mL of DMF, stir for 10 min to form a uniform solution. Immerse the prepared NiFe-LDH@Ru in the above solution and transfer it to a 50 mL reactor, and heat it at a constant temperature of 120 ° C for 10 h. Cool it naturally to room temperature, wash it with deionized water and ethanol several times, and obtain NiFe-LDH@Ru-BDT nanomaterials.

[0082] Scanning electron microscopy observations as shown in the attached Figure 7 As shown in (c), the microstructure of the NiFe-LDH@Ru-BDT material prepared in this comparative example has undergone significant changes. Unlike the regular nanosheet array in Example 1, after increasing the amount of BDT, a large amount of amorphous material appears on the surface of the material, the overall morphology becomes rough, and different regions show significantly different structural characteristics. The surface is covered with granular or flocculent amorphous materials; other regions show agglomerated or collapsed morphology. This indicates that the introduction of excessive BDT may interfere with the coordination equilibrium between Ru and NiFe-LDH, resulting in local supersaturation of organic ligands, making it impossible to form uniform modification, and instead reducing catalytic activity and stability. In contrast, the optimized BDT amount of 0.05mmol in Example 1 can achieve uniform and stable modification of Ru atoms, maintaining the structural integrity of the material while improving activity, further verifying the importance of parameter control in the technical solution of the present invention.

[0083] By comparing the examples and the comparative examples, the NiFe-LDH@Ru-BDT composite material of the present application exhibits significant performance advantages in the water electrolysis reaction. The doping of Ru atoms optimizes the electronic structure of the catalyst, improves the catalytic activity; the modification of the organic ligand stabilizes the Ru atoms through coordination, significantly enhances the stability of the catalyst; these improvements not only improve the performance of the catalyst, but also reduce the cost, making it have broad application prospects in industrial large-scale water electrolysis to produce hydrogen.

[0084] The above examples and comparative examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the examples of the present application.

Claims

1. A method for preparing organic ligand-modified Ru atom-doped NiFe-LDH material, characterized in that: The method comprises the following steps: Step 1: cutting and cleaning the nickel foam substrate, removing the surface oxide layer and organic matter by ultrasonic treatment with hydrochloric acid, deionized water, and anhydrous ethanol, and drying after pretreatment; Step 2: fully dissolving nickel salt, iron salt, ammonium fluoride and urea in deionized water under ultrasonic stirring conditions, placing the mixed solution into a high-pressure reactor, adding the dried nickel foam pretreated in step 1, sealing and performing a solvent thermal reaction, reacting at a certain temperature for a set time, and naturally cooling to room temperature. The taken-out nickel foam is washed and dried with deionized water and anhydrous ethanol in turn to obtain a regular NiFe-LDH nanosheet array grown on the nickel foam; Step 3: Add ruthenium chloride to a mixed solvent of deionized water and anhydrous ethanol, stir thoroughly to form a uniform mixed solution, transfer it to a reactor, and immerse the nickel foam on which NiFe-LDH is grown obtained in step 2 in this mixed solution, place it in an oven and heat it at a constant temperature for ion exchange. After the reaction, rinse the sample with deionized water and anhydrous ethanol several times to obtain a NiFe-LDH@Ru electrocatalyst. Step 4: dissolving the benzenedithiol BDT organic ligand in N,N-dimethylformamide DMF organic solvent under ultrasonic stirring conditions, placing the mixed solution into a high-pressure reactor, and adding the dried NiFe-LDH@Ru treated in step 3, sealing and performing a solvent thermal reaction. After reacting at a certain temperature for a set time, the reaction is naturally cooled to room temperature. After the reaction, the material is rinsed with deionized water and anhydrous ethanol several times to obtain a NiFe-LDH@Ru-BDT electrocatalyst; Wherein, the mass of ruthenium chloride in step 3 is 18-20 mg; the mass of benzenedithiol in step 4 is 7-8 mg.

2. The method for preparing the organic ligand-modified Ru atom-doped NiFe-LDH material according to claim 1, characterized in that: In step 1: the nickel foam is sequentially placed in a 2M dilute hydrochloric acid solution, deionized water, and anhydrous ethanol and ultrasonically cleaned for 10-15 minutes to remove the surface oxide layer and organic impurities.

3. The method for preparing the organic ligand-modified Ru atom-doped NiFe-LDH material according to claim 1, characterized in that: In step 2, the nickel salt is one of nickel chloride or nickel nitrate, and the iron salt is one of ferric chloride or ferric nitrate.

4. The method for preparing the organic ligand-modified Ru atom-doped NiFe-LDH material according to claim 1, characterized in that: In step 2, the molar ratio of the nickel salt to the iron salt is 8:3-10:3, and the molar ratio of ammonium fluoride to urea is 5:2-5:3; the hydrothermal reaction temperature is 100-120° C., and the reaction time is 10-12 hours.

5. The method for preparing the organic ligand-modified Ru atom-doped NiFe-LDH material according to claim 1, characterized in that The ion exchange reaction temperature in step 3 is 80-100° C., and the reaction time is 8-12 hours.

6. The method for preparing the organic ligand-modified Ru atom-doped NiFe-LDH material according to claim 1, characterized in that: In step 3, the volume of the mixed solvent of deionized water and anhydrous ethanol is 20-40 ml, and the volume ratio of deionized water to anhydrous ethanol in the solvent is 1:

1.

7. The method for preparing organic ligand-modified Ru atom-doped NiFe-LDH material according to claim 1, characterized in that: The volume of DMF solvent in step 4 is 20-40 ml.

8. The method for preparing organic ligand-modified Ru atom-doped NiFe-LDH material according to claim 1, characterized in that: In step 4, the hydrothermal reaction temperature is 100-120° C., and the reaction time is 10-12 hours.

9. A NiFe-LDH@Ru-BDT electrocatalyst, characterized in that: The electrocatalyst material is prepared by the method according to any one of claims 1 to 8.

10. Use of the NiFe-LDH@Ru-BDT electrocatalyst material according to claim 9 in water electrolysis reaction.

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