Iron-cobalt-nickel particle and carbon core-shell structure electrocatalyst, preparation method thereof and application of iron-cobalt-nickel particle and carbon core-shell structure electrocatalyst in electrocatalytic oxygen evolution reaction

Abstract

The invention discloses an iron-cobalt-nickel particle and carbon core-shell structure electrocatalyst, a preparation method thereof and application of the iron-cobalt-nickel particle and carbon core-shell structure electrocatalyst in an electrocatalytic oxygen evolution reaction, and belongs to the technical field of electrocatalysis. The preparation method of the electrocatalyst comprises the following steps: (1) dispersing hexadecyl trimethyl ammonium bromide, iron nitrate nonahydrate, cobalt nitrate hexahydrate and nickel acetate tetrahydrate in an oleic acid solvent, uniformly mixing, heating in an oil bath, and centrifuging to obtain black powder; (2) drying the black powder in a drying oven to obtain precursor powder; and (3) annealing the precursor to finally obtain the electrocatalyst with a core-shell structure. As an efficient oxygen evolution catalyst, the iron-cobalt-nickel particle-carbon core-shell structure prepared by the preparation method disclosed by the invention has excellent oxygen evolution performance. As an efficient oxygen evolution catalyst, the prepared iron-cobalt-nickel particle and carbon core-shell structure electrocatalyst has excellent oxygen evolution performance.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalysis, and in particular to an iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst and a preparation method thereof, and application thereof in an electrocatalytic oxygen evolution reaction. Background Art

[0002] At a time when renewable energy is booming, hydrogen production by water electrolysis has attracted a lot of attention due to its clean and efficient characteristics. Among them, the oxygen evolution reaction, as a key step in the anode of water electrolysis, involves four-electron transfer and has slow reaction kinetics, which greatly restricts the efficiency improvement and cost reduction of hydrogen production by water electrolysis, and has become one of the key obstacles to the development of this field. At the same time, as rechargeable metal-air batteries move towards large-scale application, efficient and stable oxygen evolution electrocatalysts are urgently needed to reduce the charging overpotential and thereby improve the battery's cycle performance and energy efficiency. Therefore, the research and development of high-performance and low-cost oxygen evolution electrocatalysts is of great practical significance at present.

[0003] Iron, cobalt, and nickel are transition metals that have similar electronic structures and similar chemical properties. The alloys they form show unique advantages in the electrocatalytic oxygen evolution reaction. On the one hand, iron-cobalt-nickel alloys usually have good electrical conductivity, which can speed up electron transmission and reduce resistance losses in the reaction; on the other hand, by adjusting the ratio of iron, cobalt, and nickel and using different preparation processes, the crystal structure, electronic structure, and surface properties of the alloy can be regulated, thereby exposing more active sites and enhancing the catalytic activity for the oxygen evolution reaction. In addition, compared with traditional precious metal oxygen evolution electrocatalysts, iron-cobalt-nickel alloys are abundant in reserves and low in cost, which makes them more economically advantageous in large-scale applications.

[0004] Although iron-cobalt-nickel alloys have shown many advantages and potentials in the field of electrocatalytic oxygen evolution, they still face some challenges and limitations at this stage. First, although there have been certain achievements in catalytic activity, compared with traditional precious metal catalysts, the ability of iron-cobalt-nickel alloys to achieve high current density at lower overpotentials needs to be improved, which may limit the efficiency of hydrogen production in actual water electrolysis hydrogen production applications. Secondly, stability is an important factor restricting its long-term application. During the long-term oxygen evolution reaction, the alloy may suffer from surface oxidation, corrosion or structural reconstruction. These changes will cause the catalytic activity to gradually decrease, thereby affecting the cycle stability and service life of the electrode. In addition, the structure-activity relationship between the alloy microstructure and catalytic performance, as well as the specific mechanism of the oxygen evolution reaction, are not yet fully understood, which to a certain extent hinders the rational design and optimization of high-performance catalysts. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide an iron-cobalt-nickel particle @ carbon core-shell structure electrocatalyst and its preparation method and application in electrocatalytic oxygen evolution reaction. The preparation method is simple, efficient, reproducible and low-cost. The prepared electrocatalyst improves the conductivity of the material, and there is a synergistic effect between the three metals of iron, cobalt and nickel, which reduces the energy barrier of the catalytic reaction and improves the activity of the oxygen evolution reaction.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0007] An iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst, wherein the catalyst is a core-shell structure, the core is an iron-cobalt-nickel particle, and the shell is a carbon layer.

[0008] Furthermore, the catalyst is a nano-scale powder, wherein the size of the iron-cobalt-nickel particles is 10-50 nm and the shell thickness is 2-5 nm.

[0009] Furthermore, the carbon layer is graphite; the iron-cobalt-nickel particles contain non-zero iron, cobalt and nickel elements, and are specifically composed of one or more of iron-nickel alloy particles, iron-cobalt-nickel alloy particles and cobalt metal particles.

[0010] The method for preparing the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst comprises the following steps:

[0011] (1) adding hexadecyltrimethylammonium bromide, ferric nitrate nonahydrate, cobalt nitrate hexahydrate and nickel acetate tetrahydrate to an oleic acid solvent in sequence, and stirring to obtain a mixed solution;

[0012] (2) placing the mixed solution obtained in step (1) in an oil bath and heating it under stirring at a temperature of 200-245° C. for a heating time of 1-3 hours, cooling it and centrifuging it to obtain a black powder, washing it several times, placing it in an oven for drying, collecting the product, and grinding it to obtain a black precursor powder;

[0013] (3) The precursor powder obtained in step (2) is subjected to high temperature annealing treatment in a tubular furnace under a nitrogen atmosphere, the high temperature annealing temperature is 860-930° C., and the annealing time is 1-3 hours. The annealed product is washed and dried to obtain a magnetic black powder, which is the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst.

[0014] Furthermore, in the raw materials of step (1), the ratio of hexadecyltrimethylammonium bromide, ferric nitrate nonahydrate, cobalt nitrate hexahydrate, nickel acetate tetrahydrate, and oleic acid is (0.1-0.5) g: (0.04-0.1) g: (0.02-0.08) g: (0.02-0.08) g: (10-40) mL; the stirring time of step (1) is 0.2-1 hour;

[0015] Furthermore, the black powder obtained by centrifugation in step (2) is washed by washing with anhydrous ethanol, deionized water and anhydrous ethanol in sequence.

[0016] Furthermore, in step (2), the drying temperature is 100° C. and the drying time is 12-24 hours.

[0017] Furthermore, during the annealing treatment in step (3), the heating rate of the tubular furnace is 3-6°C / min, the cooling rate is 3-6°C / min, and the temperature is reduced to 300°C and then naturally cooled.

[0018] Furthermore, in step (3), the product (black powder) obtained after annealing is centrifugally washed with deionized water and anhydrous ethanol in sequence, and the centrifugal product is dried in a drying oven at 50-80° C. for 10-15 hours to obtain the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst.

[0019] Furthermore, the electrocatalyst is used in the electrocatalytic oxygen evolution reaction in water electrolysis or rechargeable metal-air batteries.

[0020] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0021] 1. The present invention prepares the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst by directly annealing the precursor powder. The preparation process is simple, reproducible and low-cost, and provides a feasible preparation method for the application of non-precious metal composite materials in oxygen evolution reaction.

[0022] 2. The iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst prepared by the present invention is a core-shell structure in which a carbon layer is coated on the surface of the iron-cobalt-nickel particle. The nanocomposite material of this structure has good electrical conductivity, synergy and catalytic performance. The three elements of iron, cobalt and nickel in the iron-cobalt-nickel particle show a significant synergistic effect, which effectively reduces the energy barrier in the reaction process. At the same time, the presence of the carbon layer not only improves the conductivity of the material, but also enhances the structural stability of the catalyst, thereby significantly improving the activity of the oxygen evolution reaction.

[0023] 3. The iron-cobalt-nickel particle @ carbon core-shell structure electrocatalyst provided by the present invention is applied to the electrocatalytic oxygen evolution reaction, which reduces the oxygen evolution overpotential and exhibits excellent electrocatalytic oxygen evolution performance, providing a new idea for the design of the application of electrocatalytic oxygen evolution reaction in water electrolysis to produce hydrogen and rechargeable metal-air batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The X-ray diffraction pattern of the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst prepared in Example 1;

[0025] Figure 2This is a transmission electron microscopy image of the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst prepared in Example 1;

[0026] Figure 3 The oxygen evolution LSV performance diagram of the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst prepared in Example 1 and Comparative Examples 1-2;

[0027] Figure 4 This is the IT stability performance diagram of the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst prepared in Example 1. DETAILED DESCRIPTION

[0028] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0029] Embodiment 1:

[0030] The process of preparing the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst in this embodiment is as follows:

[0031] 1. Using 10 ml of oleic acid as solvent, add 0.2 g of hexadecyltrimethylammonium bromide, 0.08 g of ferric nitrate nonahydrate, 0.05 g of cobalt nitrate hexahydrate, and 0.05 g of nickel acetate tetrahydrate to the oleic acid in sequence, and stir for 0.5 hour to obtain a mixed solution.

[0032] 2. Preparation of precursor powder: Place the obtained mixed solution in an oil bath, heat it to 220°C, keep it warm and stir it for 2 hours, cool it and centrifuge it to obtain a black powder, wash it with anhydrous ethanol, deionized water and anhydrous ethanol in turn, and then dry it in an oven at 100°C for 20 hours. After drying, collect the product and grind it to obtain a black precursor powder.

[0033] 3. Annealing: The black precursor powder was subjected to high-temperature annealing in a tube furnace under a nitrogen atmosphere. The high-temperature annealing was maintained at 900°C for 2 hours. The heating rate in the tube furnace was 5°C / min. After the annealing was completed, the temperature was lowered to 300°C at a cooling rate of 5°C per minute and then cooled naturally. The obtained product was washed with deionized water and anhydrous ethanol in turn, and then dried in an oven at 60°C for 12 hours to obtain a magnetic black powder, which was an iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst.

[0034] Figure 1 From the X-ray diffraction pattern of the catalyst prepared in this example, it can be seen that the synthesized product is consistent with the standard PDF cards of graphite, iron-nickel alloy, and cobalt metal.

[0035] Figure 2 The transmission electron microscope image of the catalyst prepared in this example shows that the morphology is iron-cobalt-nickel particles wrapped with a carbon layer (graphite). The iron-cobalt-nickel particles (composite of iron-nickel alloy and cobalt metal) are 10-50nm in size, and the carbon layer thickness ranges from 2-5nm.

[0036] Comparative Example 1

[0037] The process of preparing the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst in this example is different from that in Example 1 in that the temperature of the annealing treatment in step 3 is 800° C., and a black powder having magnetic properties is finally obtained.

[0038] Comparative Example 2

[0039] The process of preparing the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst in this example is different from that in Example 1 in that the temperature of the annealing treatment in step 3 is 1000° C., and a magnetic black powder is finally obtained.

[0040] Application performance analysis:

[0041] The main difference between Example 1 and Comparative Examples 1 and 2 is that the sintering temperatures in step 3 are different.

[0042] The electrocatalysts prepared in Example 1 and Comparative Examples 1-2 were prepared into electrode liquids, which were drop-coated on a glassy carbon electrode with a diameter of 3 mm. After drying, the electrochemical performance was tested in an electrochemical workstation using a three-electrode system, and the oxygen evolution overpotentials shown in Table 1 were obtained:

[0043] Table 1 Comparison of oxygen evolution performance of catalysts in Example 1 and Comparative Examples 1-2

[0044] Sintering temperature <![CDATA[Overpotential / 10 mA / cm 2 > Example 1 900℃ 202mV Comparative Example 1 800℃ 343mV Comparative Example 2 1000℃ 327mV

[0045] It can be concluded from the data in Table 1 that when the sintering temperature is set to 900°C, the oxygen evolution overpotential is the smallest, which is 141 mV and 125 mV lower than the oxygen evolution overpotentials when the sintering temperatures are 800°C and 1000°C, respectively.

[0046] Figure 3 1 is the oxygen evolution LSV performance diagram of the catalysts prepared at different annealing temperatures in Example 1 and Comparative Examples 1-2. It can be seen that the catalyst material in Example 1 has excellent electrocatalytic oxygen evolution performance.

[0047] Figure 4 This is the IT stability performance diagram of the catalyst prepared in Example 1; it can be seen that the catalyst material in Example 1 has excellent stability.

[0048] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst, characterized in that: The electrocatalyst has a core-shell structure, with the core being iron-cobalt-nickel particles and the shell being a carbon layer.

2. The iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst according to claim 1, characterized in that: The catalyst is a nanometer-scale powder, wherein the size of the iron-cobalt-nickel particles is 10-50nm, and the shell thickness is 2-5nm.

3. The iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst according to claim 1, characterized in that: The carbon layer is graphite; the iron-cobalt-nickel particles contain non-zero iron, cobalt and nickel elements, and are specifically composed of one or more of iron-nickel alloy particles, iron-cobalt-nickel alloy particles and cobalt metal particles.

4. The method for preparing the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: (1) adding hexadecyltrimethylammonium bromide, ferric nitrate nonahydrate, cobalt nitrate hexahydrate and nickel acetate tetrahydrate to an oleic acid solvent in sequence, and stirring to obtain a mixed solution; (2) placing the mixed solution obtained in step (1) in an oil bath and heating it under stirring at a temperature of 200-245° C. for a heating time of 1-3 hours, cooling it and centrifuging it to obtain a black powder, washing it several times, placing it in an oven for drying, collecting the product, and grinding it to obtain a black precursor powder; (3) The precursor powder obtained in step (2) is subjected to high temperature annealing treatment in a tubular furnace under a nitrogen atmosphere, the high temperature annealing temperature is 860-930° C., and the annealing time is 1-3 hours. The annealed product is washed and dried to obtain a magnetic black powder, which is the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst.

5. The method for preparing the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst according to claim 4, characterized in that: In the raw materials of step (1), the ratio of hexadecyltrimethylammonium bromide, ferric nitrate nonahydrate, cobalt nitrate hexahydrate, nickel acetate tetrahydrate and oleic acid is (0.1-0.5) g:(0.04-0.1) g:(0.02-0.08) g:(0.02-0.08) g:(10-40) mL; the stirring time of step (1) is 0.2-1 hour (preferably 0.5 hour).

6. The method for preparing the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst according to claim 4, characterized in that: The black powder obtained by centrifugation in step (2) is washed by washing with anhydrous ethanol, deionized water and anhydrous ethanol in sequence.

7. The method for preparing the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst according to claim 4, characterized in that: In step (2), the drying temperature is 100° C. and the drying time is 12-24 hours.

8. The method for preparing the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst according to claim 4, characterized in that: During the annealing treatment in step (3), the heating rate of the tubular furnace is 3-6°C / min, the cooling rate is 3-6°C / min, and the temperature is reduced to 300°C and then naturally cooled.

9. The method for preparing the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst according to claim 4, characterized in that: In step (3), the product (black powder) obtained after annealing is centrifugally washed with deionized water and anhydrous ethanol in sequence, and the centrifugal product is dried in a drying oven at 50-80° C. for 10-15 hours to obtain the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst.

10. The use of the iron-cobalt-nickel particle@carbon core-shell structure electrocatalyst according to claim 1 in an electrocatalytic oxygen evolution reaction, characterized in that: The catalyst is used in the electrocatalytic oxygen evolution reaction in water electrolysis or rechargeable metal-air batteries.

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