A synthesis method of a uniform, stable and efficient nickel-molybdenum felt cathode

Abstract

This invention belongs to the field of electrocatalytic reaction technology and relates to a method for synthesizing a uniform, stable, and efficient nickel-molybdenum felt cathode, comprising the following steps: Step 1, preparing a composite alloy blank by using a nickel-molybdenum alloy as the core and coating the core with a layer of nickel-molybdenum-aluminum alloy to form a composite alloy blank; Step 2, preparing composite alloy fibers by bundling, stretching, and heat-treating the alloy blank to generate composite alloy fibers; Step 3, preparing a composite nickel-molybdenum felt blank by cutting, stacking, and trimming the composite alloy fibers to obtain a composite nickel-molybdenum felt blank; Step 4, preparing a composite nickel-molybdenum felt by sintering, rolling, and heat-treating the composite nickel-molybdenum felt blank under vacuum or a reducing atmosphere to produce a composite nickel-molybdenum felt of suitable thickness; Step 5, preparing a nickel-molybdenum felt cathode by alkaline activation by washing the composite nickel-molybdenum felt with a strong alkaline solution. This invention balances the performance of the active phase and the mechanical strength of the nickel-molybdenum felt cathode.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic reaction technology and relates to a method for synthesizing a uniform, stable and efficient nickel-molybdenum felt cathode. Background Technology

[0002] In the field of electrocatalysis, nickel-molybdenum intermetallic compounds are commonly used cathode electrocatalysts in alkaline electrolyzers. Fabricating them into porous structures can significantly improve their catalytic performance. Current techniques commonly use concentrated sodium hydroxide solution to remove aluminum from nickel-molybdenum-aluminum alloys, where the aluminum-nickel ratio is as high as 1:1. However, nickel-molybdenum intermetallic compounds themselves possess a uniform, stable, and ordered structure. If aluminum is directly incorporated into these compounds in a high proportion using existing techniques, it may cause alloy composition segregation, further leading to a decrease in the material's structural stability and performance. In particular, after removing aluminum from these compounds with a strong alkali, the uneven distribution of aluminum within the compound leads to a decrease in the mechanical properties of the catalyst support material, affecting the catalyst's stability. Summary of the Invention

[0003] The purpose of this invention is to provide a method for synthesizing a uniform, stable and efficient nickel-molybdenum felt cathode, in order to solve the technical problem in the prior art where aluminum alloy is directly doped into nickel-molybdenum intermetallic compounds and then aluminum is removed with a strong alkaline solution, resulting in a decrease in the mechanical properties of the catalyst support material due to alloy composition segregation and uneven distribution of aluminum elements.

[0004] The method for synthesizing a uniform, stable, and efficient nickel-molybdenum felt cathode includes the following steps.

[0005] Step 1: Make a composite alloy billet. Use a nickel-molybdenum alloy as the core and coat the core with a layer of nickel-molybdenum-aluminum alloy to form a composite alloy billet.

[0006] Step 2: Prepare composite alloy fibers by bundling, stretching and heat treating the alloy billet to generate composite alloy fibers.

[0007] Step 3: Prepare composite nickel-molybdenum blank felt by cutting, stacking and trimming the composite alloy fibers to obtain composite nickel-molybdenum blank felt.

[0008] Step 4: Prepare composite nickel-molybdenum felt. Sinter, roll and heat treat the composite nickel-molybdenum blank felt under vacuum or reducing atmosphere to produce composite nickel-molybdenum felt of appropriate thickness.

[0009] Step 5: Alkali activation to prepare nickel-molybdenum felt cathode. The composite nickel-molybdenum felt is washed with strong alkali water to form a highly active phase with a porous structure on the surface of the nickel-molybdenum-aluminum fiber, thereby obtaining the nickel-molybdenum felt cathode.

[0010] Preferably, a nickel-molybdenum alloy forms a nickel-molybdenum alloy core, and a nickel-molybdenum-aluminum alloy forms a nickel-molybdenum-aluminum alloy shell. The ratio of the diameter of the nickel-molybdenum alloy core to the thickness of the nickel-molybdenum-aluminum alloy shell ranges from 1:1 to 10:1. In the alloy billet, the atomic ratio of Ni:Mo ranges from 1:1 to 5:1, and the atomic ratio of Ni:Al ranges from 1:1 to 3:1.

[0011] Preferably, the nickel-molybdenum alloy core is made of Ni4Mo alloy, and the nickel-molybdenum aluminum alloy shell is made of Ni4MoAl4 alloy.

[0012] Preferably, in step two, several alloy billets are bundled together and stretched, and then subjected to heat treatment. The heat treatment temperature range is 1000℃~1800℃, the heating rate is 10℃ / min, the heat treatment holding time is 1h~3h, and the diameter range of the composite alloy fibers is 10μm~200μm.

[0013] Preferably, in step three, the composite alloy fibers are cut to a suitable length, with the length distributed between 10 and 200 mm; then they are stacked into a felt, and after the felt is formed, it is trimmed to obtain a composite nickel-molybdenum blank felt. The composite alloy fibers of the same composition are divided into multiple categories with different diameters, and the mass fraction of each diameter fiber is equal.

[0014] Preferably, in step three, the felt is made by stacking from bottom to top in a manner from coarse to fine.

[0015] Preferably, in step three, the felt is made by layering the felt from bottom to top in a coarse-fine-coarse pattern.

[0016] Preferably, in step three, the felt is made by layering the felt from bottom to top in a fine-coarse-fine pattern.

[0017] Preferably, in step four, under a vacuum or reducing atmosphere, the composite alloy fibers in the composite nickel-molybdenum blank felt are fused together by sintering. During sintering, the heating rate is 10℃ / min, the sintering temperature range is 400℃~1000℃, and the sintering holding time is 2h~3h. Then, the composite nickel-molybdenum blank felt is rolled to achieve a suitable thickness, with an applied pressure range of 5MPa~20MPa. The thickness of the nickel-molybdenum felt obtained after rolling ranges from 0.5mm to 5mm. Finally, it is heat-treated for shaping, with a heating rate of 5℃ / min, a heat treatment temperature range of 800℃~1000℃, and a heat treatment holding time of 1h~2h.

[0018] Preferably, in step five, the nickel-molybdenum-aluminum alloy shell of the composite alloy fiber is washed with a strong alkaline solution, and the nickel-molybdenum-aluminum alloy shell forms a porous, highly active phase, while the internal nickel-molybdenum alloy core remains a dense, high-strength nickel-molybdenum alloy phase. The porosity of the nickel-molybdenum felt cathode ranges from 68% to 90%, and the pore size of the nickel-molybdenum felt cathode varies uniformly according to the fiber diameter distribution.

[0019] This invention has the following advantages: It involves coating a nickel-molybdenum-aluminum alloy core with a nickel-molybdenum alloy to form a nickel-molybdenum-aluminum alloy shell. The resulting alloy billet is then technically stretched to form composite alloy fibers. Following these composite alloy fibers, processes such as stacking, sintering, rolling, and heat treatment are performed to form a felt. Finally, a strong alkaline solution is used for washing, transforming the nickel-molybdenum-aluminum alloy shell into an active phase. Therefore, this method can achieve active phase coating on the surface of each nickel-molybdenum alloy core. As long as the stacking is uniform, the active phase can be evenly distributed throughout the material, ensuring a consistent ratio between the active phase and the nickel-molybdenum alloy core. Furthermore, the structural strength of the nickel-molybdenum alloy core itself is not affected by alkaline activation, thus guaranteeing the mechanical properties of the nickel-molybdenum felt cathode as a catalyst support material.

[0020] The synthesis method is simple to prepare and has high production efficiency. Since the active phase and the nickel-molybdenum alloy core have the same composition, it also avoids contact corrosion between the two, while taking into account both the performance of the active phase and the mechanical strength of the nickel-molybdenum felt cathode. Attached Figure Description

[0021] Figure 1 This is a schematic flowchart illustrating the synthesis method of a uniform, stable, and efficient nickel-molybdenum felt cathode according to the present invention.

[0022] Figure 2 This is a schematic diagram of the process of steps one to three in this invention. Detailed Implementation

[0023] The following detailed description of the embodiments, with reference to the accompanying drawings, will further illustrate the specific implementation of the present invention, in order to help those skilled in the art to have a more complete, accurate, and in-depth understanding of the inventive concept and technical solution of the present invention.

[0024] To meet the requirements of low hydrogen evolution overpotential, long operating time, high current density, resistance to bubble impact, and low resistance in hydrogen production electrodes, this invention utilizes alloy fibers containing two different components to create a high-strength composite nickel-molybdenum felt cathode. A nickel-molybdenum alloy core is formed, coated with a nickel-molybdenum-aluminum alloy of a certain thickness, and then heat-treated to form a composite fiber material. The nickel-molybdenum alloy fibers serve as a supporting framework material, enhancing the stability and conductivity of the fiber felt. The aluminum in the surface nickel-molybdenum-aluminum alloy can be removed using a strong alkaline solution such as concentrated sodium hydroxide solution, resulting in a high-performance fiber with a porous surface structure.

[0025] like Figure 1 and Figure 2 As shown, this invention provides a method for synthesizing a uniform, stable, and efficient nickel-molybdenum felt cathode, comprising the following steps:

[0026] Step 1: Fabrication of the composite alloy billet. A nickel-molybdenum alloy is used as the core, and a layer of nickel-molybdenum-aluminum alloy is coated on the outside of the nickel-molybdenum alloy core to form a composite alloy billet.

[0027] This process forms a nickel-molybdenum alloy core, with Ni4Mo alloy being the optimal material; and a nickel-molybdenum-aluminum alloy shell, with Ni4MoAl4 alloy being the optimal material. During this process, the diameter of the alloy billet and the ratio between the nickel-molybdenum alloy core and the nickel-molybdenum-aluminum alloy shell (primarily considering the proportion of aluminum in the nickel-molybdenum felt processing) are controlled according to the process requirements of the nickel-molybdenum felt cathode, thereby controlling the alloy composition in the nickel-molybdenum felt. Specifically, the ratio of the nickel-molybdenum alloy core diameter to the thickness of the nickel-molybdenum-aluminum alloy shell ranges from 1:1 to 10:1. In the corresponding alloy billet, the atomic ratio of Ni:Mo ranges from 1:1 to 5:1, and the atomic ratio of Ni:Al ranges from 1:1 to 3:1.

[0028] Step 2: Preparation of composite alloy fibers. The alloy billet is bundled, stretched, and heat-treated to generate composite alloy fibers.

[0029] This step involves bundling and stretching several alloy billets (e.g., four to six alloy billets), followed by heat treatment to alter the shape and microstructure of the billets, forming stable composite alloy fibers. The number of alloy billets in each composite alloy fiber and the heat treatment process are controlled according to the process requirements of nickel-molybdenum felt. The heat treatment temperature range is 1000℃~1800℃, the heating rate is 10℃ / min, and the heat treatment holding time is 1h~3h to ensure the structural strength of the composite alloy fibers. The diameter of the composite alloy fibers ranges from 10μm to 200μm.

[0030] Step 3: Preparation of composite nickel-molybdenum blank felt. The composite alloy fibers are cut, stacked, and trimmed to obtain the composite nickel-molybdenum blank felt.

[0031] This step involves cutting the composite alloy fibers to appropriate lengths, ranging from 10 to 200 mm; then layering them into felt. The layering process controls the thickness of the laminated felt based on the required thickness of the nickel-molybdenum felt, and after lamination, it is trimmed to obtain a composite nickel-molybdenum blank felt. Composite alloy fibers of the same composition are divided into several categories according to their diameter, with each diameter having an equal mass fraction. There are three layering methods in this step: the first is layering from bottom to top in a coarse-to-fine manner; the second is layering from bottom to top in a coarse-fine-coarse (or coarse-to-fine-to-coarse) pattern; and the third is layering from bottom to top in a fine-coarse-fine (or fine-to-coarse-to-fine) pattern.

[0032] Step 4: Preparation of composite nickel-molybdenum felt. The composite nickel-molybdenum blank felt is sintered, rolled, and heat-treated under vacuum or reducing atmosphere to produce composite nickel-molybdenum felt of suitable thickness.

[0033] This step involves sintering to fuse the composite alloy fibers in the composite nickel-molybdenum felt blank together, followed by rolling to achieve a suitable thickness, and finally heat treatment for shaping. All of the above processes are performed under vacuum or a reducing atmosphere. The process parameters for this embodiment are as follows: during sintering, the heating rate is 10℃ / min, the sintering temperature range is 400℃~1000℃, and the sintering holding time is 2h~3h; during rolling under vacuum or a reducing atmosphere, the applied pressure ranges from 5MPa to 20MPa, and the thickness of the resulting nickel-molybdenum felt ranges from 0.5mm to 5mm; during heat treatment under a reducing atmosphere, the heating rate is 5℃ / min, the heat treatment temperature range is 800℃~1000℃, and the heat treatment holding time is 1h~2h.

[0034] Step 5: Preparation of nickel-molybdenum felt cathode by alkaline activation. The composite nickel-molybdenum felt is washed with a strong alkaline solution to form a highly active phase with a porous structure on the surface of the nickel-molybdenum-aluminum fibers, thereby obtaining the nickel-molybdenum felt cathode.

[0035] During the alkaline activation process, the nickel-molybdenum-aluminum alloy shell of the composite alloy fiber undergoes the following reaction when washed with a strong alkaline solution (such as concentrated sodium hydroxide solution): 2Al + 2NaOH + 2H₂O = 2NaAlO₂ + 3H₂. Because the aluminum element is dissolved by the strong alkaline solution, the nickel-molybdenum-aluminum alloy shell forms a porous, highly active phase, while the internal nickel-molybdenum alloy core remains unaffected by the strong alkaline solution, retaining a dense, high-strength nickel-molybdenum alloy phase with a stable structure. The resulting nickel-molybdenum felt cathode exhibits a porosity ranging from 68% to 90%, and the pore size varies uniformly according to the fiber diameter distribution.

[0036] Clearly, compared to simply doping aluminum into the nickel-molybdenum felt composition, this method achieves active phase coating on the surface of each nickel-molybdenum alloy core. As long as the layers are uniformly stacked, the active phase can be evenly distributed throughout, with a consistent ratio between the active phase and the nickel-molybdenum alloy core. Furthermore, the structural strength of the nickel-molybdenum alloy core itself is unaffected by alkaline activation, ensuring the mechanical properties of the nickel-molybdenum felt cathode as a catalyst support material. The tensile strength of the nickel-molybdenum felt cathode obtained in the example is approximately 19 N / cm². 2 .

[0037] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A method for synthesizing a uniform, stable, and efficient nickel-molybdenum felt cathode, characterized in that: Includes the following steps: Step 1: Make a composite alloy billet. Use a nickel-molybdenum alloy as the core and coat the nickel-molybdenum alloy core with a layer of nickel-molybdenum-aluminum alloy to form a composite alloy billet. The nickel-molybdenum alloy forms the nickel-molybdenum alloy core, and the nickel-molybdenum-aluminum alloy forms the nickel-molybdenum-aluminum alloy shell. The ratio of the diameter of the nickel-molybdenum alloy core to the thickness of the nickel-molybdenum-aluminum alloy shell is in the range of 1:1 to 10:

1. In the alloy billet, the atomic ratio of Ni:Mo ranges from 1:1 to 5:1, and the atomic ratio of Ni:Al ranges from 1:1 to 3:

1. The nickel-molybdenum alloy core is made of Ni4Mo alloy, and the nickel-molybdenum aluminum alloy shell is made of Ni4MoAl4 alloy. Step 2: Prepare composite alloy fibers by bundling, stretching and heat-treating the alloy billet to generate composite alloy fibers; Step 3: Prepare composite nickel-molybdenum blank felt by cutting, stacking and trimming the composite alloy fibers to obtain composite nickel-molybdenum blank felt; In step three, the composite alloy fibers are cut to a suitable length, with the length distributed between 10 and 200 mm; then they are stacked into a felt, and after the felt is formed, it is trimmed to obtain a composite nickel-molybdenum blank felt. The composite alloy fibers of the same composition are divided into several categories with different thicknesses according to their diameter, and the mass fraction of each diameter of fiber is equal. Step 4: Prepare composite nickel-molybdenum felt. Sinter, roll and heat treat the composite nickel-molybdenum blank felt under vacuum or reducing atmosphere to produce composite nickel-molybdenum felt of appropriate thickness. Step 5: Alkali activation to prepare nickel-molybdenum felt cathode. The composite nickel-molybdenum felt is washed with sodium hydroxide solution to form a porous, highly active phase on the surface of the nickel-molybdenum-aluminum fiber. The porosity of the nickel-molybdenum felt cathode ranges from 68% to 90%, thus obtaining the nickel-molybdenum felt cathode.

2. The method for synthesizing a uniform, stable, and efficient nickel-molybdenum felt cathode according to claim 1, characterized in that: In step two, several alloy billets are bundled together and stretched, and then subjected to heat treatment. The heat treatment temperature range is 1000℃~1800℃, the heating rate is 10℃ / min, the heat treatment holding time is 1h~3h, and the diameter range of the composite alloy fibers is 10μm~200μm.

3. The method for synthesizing a uniform, stable, and efficient nickel-molybdenum felt cathode according to claim 1, characterized in that: In step three, the felt is made by stacking from bottom to top in a manner from coarse to fine.

4. The method for synthesizing a uniform, stable, and efficient nickel-molybdenum felt cathode according to claim 1, characterized in that: In step three, the felt is made by layering the felt from bottom to top in a coarse-fine-coarse pattern.

5. The method for synthesizing a uniform, stable, and efficient nickel-molybdenum felt cathode according to claim 1, characterized in that: In step three, the felt is made by layering the felt from bottom to top according to the pattern of fine-coarse-fine.

6. The method for synthesizing a uniform, stable, and efficient nickel-molybdenum felt cathode according to claim 1, characterized in that: In step four, under vacuum or reducing atmosphere, the composite alloy fibers in the composite nickel-molybdenum blank felt are fused together by sintering. During sintering, the heating rate is 10℃ / min, the sintering temperature range is 400℃~1000℃, and the sintering holding time is 2h~3h. Then, the composite nickel-molybdenum blank felt is rolled to achieve a suitable thickness, with the applied pressure range being 5MPa~20MPa. The thickness of the nickel-molybdenum felt obtained after rolling is 0.5mm~5mm. Finally, it is heat-treated for shaping, with a heating rate of 5℃ / min, a heat treatment temperature range of 800℃~1000℃, and a heat treatment holding time of 1h~2h.

Images