Method for preparing porous nickel particles by hydrothermal-etching method

Abstract

The invention provides a method for preparing porous nickel particles by utilizing a hydrothermal-etching method. The method comprises the following steps: 1, preparing nickel salt and aluminum salt into a mixed solution according to a certain proportion; 2, putting the mixed solution into a high-pressure reaction kettle, adding a reducing agent to reduce Ni < 2 + > into N , converting aluminum ions into Al (OH) 3, and putting seed crystals into the solution to enable N and Al (OH) 3 to grow on the seed crystals in an attached manner to obtain Ni-Al (OH) 3; 3, taking out the grown Ni-coated Al (OH) 3, placing the Ni-coated Al (OH) 3 in a strong alkaline solution, and dissolving Al (OH) 3 to obtain porous nickel particles; and 4, washing and drying the porous nickel particles. A new thought is provided for preparing the porous nickel particles, the prepared porous nickel particles are stable in pore, the specific surface area is remarkably increased compared with traditional porous nickel, the process is short, conversion loss is low, meanwhile, the prepared product is in the nanoscale and has more active sites, and the catalytic performance of the porous nickel particles is more excellent compared with a traditional nickel-based catalyst.

Description

Technical Field

[0001] This invention belongs to the field of nanoporous catalytic materials, specifically a method for preparing porous nickel particles using a hydrothermal-etching method. Background Technology

[0002] Porous nickel nanoparticles, as a novel functional material possessing metallic conductivity, high specific surface area, and controllable pore structure, have shown significant application value in catalysis, energy storage, sensors, and filtration separation. Their preparation primarily involves forming nanoscale porous networks through processes such as dealloying, electrodeposition, or powder metallurgy, thereby endowing the material with unique physicochemical properties. However, existing preparation techniques still have significant limitations, restricting their industrial application.

[0003] Dealloying is a method for preparing nanoporous metallic materials by selectively etching specific components in an alloy. Traditional dealloying methods require the selective etching of alloy precursors using highly corrosive solutions such as hydrofluoric acid, which presents problems such as cumbersome process steps and difficult waste treatment. Qin Chunling et al. used Ni-Mn alloy acid etching to prepare nanoporous nickel bulk materials in their patent "Preparation Method of Nanoporous Nickel Bulk" (Patent Publication No.: CN103938130A), but the conditions for preparing precursor alloys using this method are still quite harsh, energy-intensive, and cause significant pollution on a large scale. Powder metallurgy is an advanced process technology for preparing metallic materials and products through forming and sintering of metal powders or mixtures of metal and non-metal powders. Powder metallurgy requires the addition of pore-forming agents (such as PMMA) and relies on high-temperature sintering, resulting in low porosity (usually <30%), poor pore connectivity, and residual pore-forming agents affecting material stability. While the method disclosed by Zou Gaohuai et al. in "A Porous Nickel and Its Preparation Method" (Patent Publication No.: CN119566305A) improves production efficiency through continuous extrusion molding, the resulting porous nickel exhibits insufficient pore uniformity, and its mechanical strength is insufficient to meet the requirements of high-temperature and high-pressure applications. Nanoporous nickel electrode materials also have wide applications in the field of supercapacitors, but often face problems such as low active material loading and poor conductivity. Qin Chunling et al. in "A Nanoporous Nickel / Nickel Oxide Supercapacitor Electrode Material and Its Preparation Method" (Patent Publication No.: CN107240507A) used a dealloying combined with oxidation soaking-heat treatment method to prepare NiO / Ni composite electrodes, but the uncontrollable crystal structure of nickel oxide easily leads to insufficient cycle stability. Existing technical solutions mostly focus on laboratory-scale preparation and lack continuous production equipment design. Kang Jianli et al., in their paper "A Method for Preparing High-Strength Nanoporous Nickel Films" (Patent Publication No.: CN103774149A), used a powder metallurgy-dealloying method to prepare high-strength nanoporous nickel films. However, this free corrosion method requires prolonged immersion (12-48 hours), and the product size is relatively limited, failing to meet the demands of industrial-grade large-area film materials. Therefore, developing a simple, environmentally friendly, and scalable nanoporous nickel preparation technology, while simultaneously achieving controllable pore structure, excellent mechanical properties, and improved adaptability for functional applications, has become a pressing technical challenge in this field. This invention, through innovative process design, overcomes the aforementioned technical bottlenecks, providing a new approach for the efficient preparation and industrial application of porous nickel particles. Summary of the Invention

[0004] A method for preparing porous nickel particles using a hydrothermal-etching method includes the following steps:

[0005] Step 1: Prepare the mixed solution;

[0006] A mixed solution is prepared by mixing nickel salt and aluminum salt in a certain proportion;

[0007] Step 2: Preparation of Ni@Al(OH)3 under alkaline conditions;

[0008] The mixed solution and seed crystals were placed in a reaction vessel and a reducing agent was added. The pH was then adjusted to alkaline to allow Ni to react. 2+ Ni and aluminum ions are reduced to Al(OH)3, and Ni and Al(OH)3 are attached to the seed crystal to grow Ni@Al(OH)3; the high-temperature reactor consists of (1) a motor, (2) a heating layer, (3) a temperature measuring port / pressure measuring port, (4) a stirring blade, and (5) a feed port / discharge port;

[0009] Step 3: Dissolve Al(OH)3 to obtain porous nickel nanoparticles;

[0010] The grown Ni@Al(OH)3 was removed and placed in a strongly alkaline solution to dissolve Al(OH)3, thereby obtaining porous nickel nanoparticles.

[0011] Step 4: Cleaning and drying the prepared porous nickel nanoparticles

[0012] The porous nickel particles are washed by first washing with deionized water 3 to 5 times, then washing with anhydrous ethanol 3 to 5 times, and then drying.

[0013] Principle of this invention

[0014] During the reduction process, because the solution is weakly alkaline, the reducing agent hydrazine (N2H4) can reduce Ni in an alkaline environment. 2+ Reduced to Ni, while aluminum ions (Al) are produced in a weakly alkaline environment. 3+ It will react with hydroxide ions (OH-) - The reduced nickel is then coated with aluminum hydroxide to form Ni@Al(OH)3. To accelerate the reaction rate, nano-nickel seed crystals are added to the reactor as growth sites for Ni@Al(OH)3. Due to the seed effect, Ni@Al(OH)3 particles adhere to the nano-nickel seed crystals and grow into a nano-Ni@Al(OH)3 composite. The reactions that occur during the reduction process are shown in (1) to (2).

[0015] 2Ni 2+ +N₂H₄+4OH - =2Ni + N2↑ + 4H2O (1)

[0016] 3OH - +Al 3+ =Al(OH)3 (2)

[0017] The prepared nano-Ni@Al(OH)3 composite was placed in a strongly alkaline solution. Since Al(OH)3 is an amphoteric hydroxide, its unique two-phase solubility allows it to dissolve in both acidic and alkaline environments. Nickel, as a metal, can only be dissolved in acid and not in alkaline conditions. This allows for the targeted removal of Al(OH)3 from the nano-Ni@Al(OH)3 composite, creating pores and obtaining a porous nano-nickel structure. A reaction (3) occurs during this process.

[0018] Al(OH)3+OH - =[Al(OH)4] - (3) Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the invention or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of a high-temperature reactor used to prepare porous nickel particles in Example 1 of the present invention;

[0021] Figure 2 This is a scanning electron microscope image of the porous nickel particle material prepared in Example 1 of the present invention;

[0022] Figure 3 The XRD pattern of the porous nickel particle material prepared in Example 1 of this invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] It should be understood that the step numbers used in the text are for ease of description only and are not intended to limit the order in which the steps are performed.

[0025] It should be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0026] The terms “comprising” and “including” indicate the presence of the described feature, whole, step, operation, element and / or component, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0027] The term “and / or” refers to any combination of one or more of the associated listed items, as well as all possible combinations, and includes these combinations.

[0028] Example 1

[0029] A solution was prepared by mixing nickel sulfate and aluminum sulfate in a 1:1 ratio (molar ratio of nickel to aluminum) and placed in a high-temperature reactor. Nano-sized nickel seed crystals were added to the reactor as a growth source, and hydrazine, a reducing agent, was added to adjust the pH to a weakly alkaline state. After sealing, the reactor was reacted at 150°C for 1 hour to obtain Ni@Al(OH)3 conjugates. The Ni@Al(OH)3 conjugates were dissolved in 1M NaOH solution for 0.5 hours and then removed. They were washed 5 times with deionized water and then 5 times with anhydrous ethanol. Finally, they were dried in a vacuum drying oven at 60°C for 8 hours to obtain porous nickel particles with stable pore structure.

[0030] Example 2

[0031] A solution was prepared by mixing nickel sulfate and aluminum sulfate in a 1:1 ratio (molar ratio of nickel to aluminum) and placed in a high-temperature reactor. Nano-sized nickel crystals were added to the reactor as a growth source, and hydrazine, a reducing agent, was added to adjust the pH to a weakly alkaline state. After sealing, the reactor was reacted at 125°C for 2 hours to obtain Ni@Al(OH)3 conjugates. The Ni@Al(OH)3 conjugates were dissolved in 0.1M NaOH solution for 2 hours and then removed. They were washed three times with deionized water and then three times with anhydrous ethanol. Finally, they were dried in a vacuum drying oven at 70°C for 6 hours to obtain porous nickel particles with stable pore structure.

[0032] Example 3

[0033] A solution was prepared by mixing nickel sulfate and aluminum sulfate in a 1:1 ratio (molar ratio of nickel to aluminum) and placed in a high-temperature reactor. Nano-sized nickel crystals were added to the reactor as a growth source, and hydrazine, a reducing agent, was added to adjust the pH to a weakly alkaline state. After sealing, the reactor was reacted at 100°C for 4 hours to obtain Ni@Al(OH)3 conjugates. The Ni@Al(OH)3 conjugates were dissolved in 1M NaOH solution for 0.5 hours and then removed. They were washed four times with deionized water and then four times with anhydrous ethanol. Finally, they were dried in a vacuum drying oven at 80°C for 3 hours to obtain porous nickel particles with stable pore structure.

[0034] The present invention has the following beneficial effects:

[0035] I. Compared with traditional porous nano-nickel processes, this invention has a shorter process, simpler equipment, and lower energy consumption, making it suitable for industrial production.

[0036] Second, the product chimera can be obtained in only one step in this invention, with high utilization and conversion rates of raw materials, which can significantly reduce preparation costs.

[0037] Third, the realization path from product chimera to final product in this invention can be achieved in an alkaline environment.

[0038] Fourth, the intermediate aluminum resource in this invention can be recycled, with no excess by-products, which is environmentally friendly. In addition, the hydrogen generated during the preparation process can also be collected to increase output value.

[0039] V. Compared with other methods for preparing porous nickel nanoparticles, the porous nickel particles prepared by this invention have a more stable structure, higher porosity, and more uniform distribution.

[0040] This invention provides a method for preparing porous nickel particles using a hydrothermal-etching method.

[0041] The above-described 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing porous nickel particles using a hydrothermal-etching method, characterized in that, Includes the following steps: Step 1: Prepare the mixed solution; A mixed solution is prepared by mixing nickel salt and aluminum salt in a certain proportion; Step 2: Preparation of Ni@Al(OH)3 under alkaline conditions; The mixed solution and seed crystals were placed in a reaction vessel and a reducing agent was added. The pH was then adjusted to alkaline to allow Ni to react. 2+ Ni and aluminum ions are reduced to Al(OH)3, and Ni and Al(OH)3 are attached to the seed crystal to grow Ni@Al(OH)3; the high-temperature reactor consists of (1) a motor, (2) a heating layer, (3) a temperature measuring port / pressure measuring port, (4) a stirring blade, and (5) a feed port / discharge port; Step 3: Dissolve Al(OH)3 to obtain porous nickel nanoparticles; The grown Ni@Al(OH)3 was removed and placed in a strongly alkaline solution to dissolve Al(OH)3, thereby obtaining porous nickel nanoparticles. Step 4: Cleaning and drying the prepared porous nickel nanoparticles The porous nickel particles are washed by first washing with deionized water 3 to 5 times, then washing with anhydrous ethanol 3 to 5 times, and then drying.

2. The method for preparing porous nickel particles using a hydrothermal-etching method according to claim 1, characterized in that, The nickel salt and aluminum salt in step one are NiSO4 and Al2(SO4)3, respectively, but are not limited to these. Other soluble nickel and aluminum compounds should also be included here.

3. The method for preparing porous nickel particles using a hydrothermal-etching method according to claim 1, characterized in that, The reducing agent in step two is hydrazine (N2H4), but it is not limited to this; other applicable reducing substances should also be included.

4. The method for preparing porous nickel particles using a hydrothermal-etching method according to claim 1, characterized in that, The pH adjustment range in step two is 6 to 8.

5. The method for preparing porous nickel particles using a hydrothermal-etching method according to claim 1, characterized in that, The seed crystals in step two can be nano-nickel seed crystals, but are not limited to them. Seed crystals that can stably grow nano-nickel and alumina should also be included here.

6. The method for preparing porous nickel particles using a hydrothermal-etching method according to claim 1, characterized in that, In step two, the reaction temperature inside the high-temperature reactor is 80–200°C, and the reaction time is 0.5–5 hours.

7. The method for preparing porous nickel particles using a hydrothermal-etching method according to claim 1, characterized in that, The strong alkaline solution in step three is a 1M NaOH solution with a pH of 14, but it is not limited to this; other strong alkaline solutions should also be included here.

8. The method for preparing porous nickel particles using a hydrothermal-etching method according to claim 1, characterized in that, In step four, the drying temperature is 60–80°C and the drying time is 3–10 hours. The drying should be carried out in a protective atmosphere or vacuum environment.

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