A Preparation Method for Regulating the Order of Sulfidation and Alkaline Corrosion of Layered Double Hydroxide Heterostructure Electrocatalysts

Abstract

The present invention belongs to the technical field of material preparation, and particularly relates to a preparation method of a layered double hydroxide heterostructure electrocatalyst with regulated vulcanization and alkaline corrosion sequence, comprising the following steps: Dissolve CoCl2·6H2O, FelCl3·6H2O, AlCl3·6H2O, ammonium fluoride and urea in deionized water, stir to obtain solution A, and react at 100 °C; After naturally cooling to room temperature, take out the nickel foam and wash and dry it; Stir thiourea with water to form solution B, put the nickel foam into solution B, and react at 140 °C; Take out, wash, dry and then put it into a reaction kettle containing NaOH solution, and react at 120 °C to obtain the product. The present invention adopts a simple preparation method to carry out vulcanization and alkaline solution corrosion treatment on the Al-containing layered double hydroxide and optimize the process, and can prepare an electrocatalyst with high efficiency, low cost and high stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of material preparation, and specifically relates to a preparation method of a layered double hydroxide heterostructure electrocatalyst with regulated sulfurization and alkaline corrosion sequence. Background Art

[0002] Replacing traditional fossil fuels with green clean energy to reduce carbon emissions is an important means to achieve the "dual carbon" goals of carbon peak and carbon neutrality. As one of the green clean energies, hydrogen energy has the advantages of being pollution-free, zero carbon dioxide emission, high energy density, renewable, etc., and is most promising to become one of the next-generation clean energies. As one of the most effective ways to produce hydrogen energy, electrolytic water hydrogen production is restricted by the slow kinetic processes of the two half-reactions of hydrogen evolution and oxygen evolution during the electrocatalytic decomposition process, resulting in slow catalytic progress and low efficiency. Therefore, efficient electrocatalysts have become the first choice to improve catalytic performance.

[0003] Currently, catalysts based on noble metals exhibit excellent catalytic efficiency, but their high cost, low reserves, and instability limit their industrial application scope. Non-noble metal-based catalysts based on transition metal layered double hydroxides are expected to become substitutes for noble metal-based catalysts due to the high theoretical activity and rich reserves brought by their unique layered structure, electronic structure, and high specific surface area. However, in actual research, it is found that the interlayer conductivity of layered double hydroxides is low, they are prone to agglomeration, and the durability and stability of the catalysts are poor, making their catalytic properties far lower than the theoretical values. Therefore, modifying transition metal layered double hydroxides to increase the number of active sites, improve conductivity, and reduce agglomeration can greatly improve the electrocatalytic performance of layered double hydroxides.

[0004] It has been widely concerned that sulfurization can improve the performance of catalysts; there has also been some research on corroding Al-containing materials with alkaline solutions. However, there are extremely few reports on the research of the dual effects of sulfurization and alkaline corrosion and the influence of the sequence on the structure and performance of the catalysts. Therefore, using a simple preparation method to perform sulfurization and alkaline solution corrosion treatment on Al-containing layered double hydroxides and optimizing the process to prepare high-efficiency, low-cost, and high-stability electrocatalysts has certain application prospects in industry. Summary of the Invention

[0005] Aiming at the above problems existing in the existing layered double hydroxide catalytic materials, the purpose of the present invention is to provide a preparation method of a layered double hydroxide heterostructure electrocatalyst with regulated sulfurization and alkaline corrosion sequence.

[0006] To achieve the above technical purposes and reach the above technical effects, the present invention is realized through the following technical solutions:

[0007] A preparation method for regulating the order of sulfidation and alkaline corrosion of a layered double hydroxide heterostructure electrocatalyst, comprising the following steps:

[0008] S1. Dissolve CoCl 2 ·6H 2 O, FelCl 3 ·6H 2 O, AlCl 3 ·6H 2 O, ammonium fluoride, and urea in deionized water, and magnetically stir for a period of time to obtain solution A;

[0009] S2. Transfer solution A into a high-pressure hydrothermal reaction kettle, place nickel foam in it, then seal the reaction kettle and put it into an oven, and react at 100 °C for a period of time;

[0010] S3. After the reaction in the kettle is completed, stop heating, and let the reaction kettle cool naturally; after the reaction kettle cools naturally to room temperature, take out the nickel foam and wash it, then put the nickel foam into a vacuum drying oven and dry it at 60 °C for a period of time, and the obtained nickel foam is denoted as CoFeAl LDH;

[0011] S4. Then, put thiourea into deionized water and stir to form solution B. Take out the CoFeAl LDH obtained in step S3 at room temperature and put it into solution B, transfer it into a high-pressure hydrothermal reaction kettle, and react at 140 °C for a period of time; then take out the nickel foam and wash it with absolute ethanol, put it into a vacuum drying oven and dry it at 60 °C for a period of time;

[0012] S5. Put the nickel foam obtained in step S4 into a high-pressure hydrothermal reaction kettle containing NaOH solution, and react at 120 °C for a period of time, and the finally obtained product is denoted as CoFeAl-T-NaOH.

[0013] Further, in step S1, the molar ratio of CoCl 2 ·6H 2 O, FelCl 3 ·6H 2 O, AlCl 3 ·6H 2 O, ammonium fluoride, and urea is x:y:z:10z:70z, and (x + y):z = 2 - 4:1.

[0014] Further, in step S1, the magnetic stirring time is 20 - 40 minutes.

[0015] Further, in step S2, before using the nickel foam, ultrasonically clean it with deionized water and ethanol for 4 - 8 minutes.

[0016] Further, in step S3, the nickel foam taken out is washed 3 times each with deionized water and ethanol; in step S4, the nickel foam taken out is washed 1 - 3 times with absolute ethanol.

[0017] Further, in steps S3 and S4, the drying time of the vacuum drying oven is 6 - 24 h.

[0018] Further, in step S4, the molar ratio of thiourea to CoCl 2 ·6H 2 O in step S1 is 3:4.

[0019] Further, in step 5), the molar concentration of the NaOH solution is 5.0 mol / l.

[0020] The beneficial effects of the present invention are as follows:

[0021] The present invention uses a simple preparation method to carry out sulfidation and alkaline solution corrosion treatment on the Al-containing layered double hydroxide and optimizes the process, and can prepare an electrocatalyst with high efficiency, low cost and high stability.

[0022] Of course, it is not necessary for any product implementing the present invention to achieve all the above advantages simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0024] Figure 1 is the XRD pattern of some products;

[0025] Figure 2 is the SEM image of the product CoFeAl LDH;

[0026] Figure 3 is the SEM image of the product CoFeAl-T;

[0027] Figure 4 is the SEM image of the product CoFeAl-NaOH;

[0028] Figure 5 is the SEM image of the product CoFeAl-NaOH-T;

[0029] Figure 6 is the SEM image of the product CoFeAl-T-NaOH;

[0030] Figure 7Performance diagrams of electrocatalytic oxygen evolution, hydrogen evolution, and overall water splitting of partial products at room temperature in 1.0 M KOH;

[0031] Figure 8 Performance diagrams of electrocatalytic hydrogen evolution and oxygen evolution of the product CoAl-T-NaOH at room temperature in 1.0 M KOH;

[0032] Figure 9 Performance diagrams of electrocatalytic hydrogen evolution and oxygen evolution of the product FeAl-T-NaOH at room temperature in 1.0 M KOH. Detailed implementation manners

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0034] Example 1

[0035] Step 1): Dissolve 0.8 mmol CoCl 2 ·6H 2 O, 0.4 mmol FelCl 3 ·6H 2 O, 0.4 mmol AlCl 3 ·6H 2 O, 4 mmol ammonium fluoride, and 28 mmol urea in 40 ml of deionized water and stir magnetically for 30 minutes; then transfer the above solution into a 50 ml high-pressure hydrothermal reaction kettle, and place a nickel foam (1 cm × 2 cm) ultrasonically cleaned with deionized water and ethanol for 5 minutes each. After that, seal the reaction kettle and place it in an oven, and react at 100 °C for 6 hours. After naturally cooling to room temperature, take out the nickel foam and wash it 3 times with deionized water and ethanol each, and then place it in a vacuum drying oven and dry it at 60 °C for 12 hours. The obtained product is denoted as CoFeAl LDH.

[0036] Step 2): Put 0.6 mmol of thiourea into 40 ml of deionized water and stir for 10 minutes to form a solution. Take out the nickel foam obtained in step 1 at room temperature and put it into this solution, transfer it into a 50 ml high-pressure hydrothermal reaction kettle, react at 140 °C for 5 hours, then take it out and wash it with absolute ethanol, and place it in a vacuum drying oven and dry it at 60 °C for 12 hours.

[0037] Step 3): Put the nickel foam obtained in step 2 into a high-pressure hydrothermal reaction kettle containing 30 ml of NaOH (5.0 mol / l) and react at 120 °C for 12 hours. The obtained product is denoted as CoFeAl-T-NaOH.

[0038] Comparative Example 1

[0039] Step 1): Dissolve 0.8 mmol of CoCl 2 ·6H 2 O, 0.4 mmol of FelCl 3 ·6H 2 O, 0.4 mmol of AlCl 3 ·6H 2 O, 4 mmol of ammonium fluoride, and 28 mmol of urea in 40 ml of deionized water and stir magnetically for 30 minutes; then transfer the above solution into a 50 ml high-pressure hydrothermal reactor, and place a nickel foam (1 cm × 2 cm) that has been ultrasonically cleaned with deionized water and ethanol for 5 minutes each. After that, seal the reactor and place it in an oven, and react at 100 °C for 6 hours. After naturally cooling to room temperature, take out the nickel foam and wash it 3 times with deionized water and ethanol each, and then place it in a vacuum drying oven and dry it at 60 °C for 12 hours. The obtained product is denoted as CoFeAl LDH.

[0040] Step 2): Place the nickel foam obtained in Step 1 into a 50 ml high-pressure hydrothermal reactor containing 30 ml of NaOH (5.0 mol / l) and react at 120 °C for 12 hours.

[0041] Step 3): Dissolve 0.6 mmol of thiourea in 40 ml of deionized water and stir for 10 minutes to form a solution. After taking out the nickel foam obtained in Step 2 at room temperature, place it into this solution, transfer it into a 50 ml high-pressure hydrothermal reactor, react at 140 °C for 5 hours, then take it out and wash it with absolute ethanol, and place it in a vacuum drying oven and dry it at 60 °C for 12 hours. The obtained product is denoted as CoFeAl-NaOH-T.

[0042] Comparative Example 2

[0043] Step 1): Dissolve 0.8 mmol of CoCl 2 ·6H 2 O, 0.4 mmol of FelCl 3 ·6H 2 O, 0.4 mmol of AlCl 3 ·6H 20.8 mmol CoCl

[0044] Step 2): Dissolve 0.6 mmol of thiourea in 40 ml of deionized water and stir for 10 minutes to form a solution. After taking out the nickel foam obtained in Step 1) at room temperature, put it into this solution, transfer it into a 50 ml high-pressure hydrothermal reactor, react at 140 °C for 5 hours, then take it out, wash it with absolute ethanol, and put it into a vacuum drying oven to dry at 60 °C for 12 hours. The obtained product is denoted as CoFeAl-T.

[0045] Comparative Example 3

[0046] Step 1): Dissolve 0.8 mmol CoCl 2 ·6H 2 O, 0.4 mmol FelCl 3 ·6H 2 O, 0.4 mmol AlCl 3 ·6H 2 O, 4 mmol of ammonium fluoride and 28 mmol of urea are dissolved in 40 ml of deionized water and stirred magnetically for 30 minutes; then the above solution is transferred into a 50 ml high-pressure hydrothermal reactor, and nickel foam (1 cm × 2 cm) ultrasonically cleaned with deionized water and ethanol for 5 minutes each is put in. After that, the reactor is sealed and put into an oven, and reacted at 100 °C for 6 hours. After naturally cooling to room temperature, take out the nickel foam and wash it 3 times with deionized water and ethanol each, then put it into a vacuum drying oven and dry at 60 °C for 12 hours. The obtained product is denoted as CoFeAl LDH.

[0047] Step 2): Put the nickel foam obtained in Step 1) into a high-pressure hydrothermal reactor containing 30 ml of NaOH (5.0 mol / l) and react at 120 °C for 12 hours. The obtained product is denoted as CoFeAl-NaOH.

[0048] Comparative Example 4

[0049] Step 1): Dissolve 0.8 mmol CoCl 2 ·6H 2 O, 0.4 mmol AlCl 3 ·6H 20.8 mmol FelCl

[0050] Step 2): Dissolve 0.6 mmol of thiourea in 40 ml of deionized water and stir for 10 minutes to form a solution. Take out the nickel foam obtained in Step 1) at room temperature and put it into this solution. Transfer it into a 50 ml high-pressure hydrothermal reactor and react at 140 °C for 5 hours. Then take it out, wash it with absolute ethanol, and put it into a vacuum drying oven to dry at 60 °C for 12 hours.

[0051] Step 3): Put the nickel foam obtained in Step 2) into a high-pressure hydrothermal reactor containing 30 ml of NaOH (5.0 mol / l) and react at 120 °C for 12 hours. The obtained product is denoted as CoAl-T-NaOH.

[0052] Comparative Example 5

[0053] ·6H 3 ·6H 2 O, 0.4 mmol AlCl 3 ·6H 2 O, 4 mmol of ammonium fluoride, and 28 mmol of urea are dissolved in 40 ml of deionized water and stirred magnetically for 30 minutes; then transfer the above solution into a 50 ml high-pressure hydrothermal reactor, and put in nickel foam (1 cm × 2 cm) that has been ultrasonically cleaned with deionized water and ethanol for 5 minutes each. After that, seal the reactor and put it into an oven, and react at 100 °C for 6 hours. After naturally cooling to room temperature, take out the nickel foam and wash it 3 times with deionized water and ethanol each, and then put it into a vacuum drying oven to dry at 60 °C for 12 hours. The obtained product is denoted as CoFeAlLDH.

[0054] Step 2): Dissolve 0.6 mmol of thiourea in 40 ml of deionized water and stir for 10 minutes to form a solution. Take out the nickel foam obtained in Step 1) at room temperature and put it into this solution. Transfer it into a 50 ml high-pressure hydrothermal reactor and react at 140 °C for 5 hours. Then take it out, wash it with absolute ethanol, and put it into a vacuum drying oven to dry at 60 °C for 12 hours.

[0055] Step 3): Put the nickel foam obtained in Step 2) into a high-pressure hydrothermal reactor containing 30 ml of NaOH (5.0 mol / l) and react at 120 °C for 12 hours. The resulting product is denoted as FeAl-T-NaOH.

[0056] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification in order to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A preparation method for regulating the order of sulfidation and alkaline corrosion of a layered double hydroxide heterostructure electrocatalyst, characterized in that, it includes the following steps: S1. Dissolve CoCl 2 ·6H 2 O, FelCl 3 ·6H 2 O, AlCl 3 ·6H 2 O, ammonium fluoride, and urea in deionized water, and magnetically stir for a period of time to obtain solution A; wherein, the molar ratio of CoCl 2 ·6H 2 O, FelCl 3 ·6H 2 O, AlCl 3 ·6H 2 O, ammonium fluoride, and urea is x:y:z:10z:70z, and (x + y):z = 2 - 4:1; S2. Transfer solution A into a high-pressure hydrothermal reactor, put in nickel foam, then seal the reactor and place it in an oven, and react at 100 °C for a period of time; S3. After the reaction in the reactor is completed, stop heating, and let the reactor cool naturally; after the reactor cools naturally to room temperature, take out the nickel foam and wash it, then put the nickel foam into a vacuum drying oven and dry it at 60 °C for a period of time, and the obtained nickel foam is denoted as CoFeAlLDH; S4. Then, put thiourea into deionized water and stir to form solution B. The molar ratio of thiourea to CoCl 2 ·6H 2 O in step S1 is 3:4; After taking out the CoFeAl LDH obtained in step S3 at room temperature, put it into solution B, transfer it into a high-pressure hydrothermal reaction kettle, and react at 140 °C for a period of time; Then take out the nickel foam, wash it with absolute ethanol, put it into a vacuum drying oven and dry it at 60 °C for a period of time; S5. Put the nickel foam obtained in step S4 into a high-pressure hydrothermal reactor containing NaOH solution, and react at 120 °C for a period of time, and the final obtained product is denoted as CoFeAl-T-NaOH.

2. The preparation method according to claim 1, characterized in that: In step S1, the magnetic stirring time is 20 to 40 minutes.

3. The preparation method according to claim 1, characterized in that: In step S2, before using the nickel foam, ultrasonically clean it with deionized water and ethanol for 4 to 8 minutes in sequence.

4. The preparation method according to claim 1, characterized in that: In step S3, the taken-out nickel foam is washed 3 times with deionized water and ethanol respectively; in step S4, the taken-out nickel foam is washed 1 - 3 times with absolute ethanol.

5. The preparation method according to claim 1, characterized in that: In steps S3 and S4, the drying time of the vacuum drying oven is 6 to 24 h.

6. The preparation method according to claim 1, characterized in that: In step 5), the molar concentration of the NaOH solution is 5.0 mol / l.

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