A heteroatomized honeycomb carbon anchored cobalt / cobalt oxide heterostructure nanocomposite and a preparation method thereof

Abstract

The application provides a kind of heteroatomized honeycomb carbon anchoring cobalt / cobalt oxide heterostructure nanocomposite and a preparation method thereof.The above preparation method comprises the following steps: step S1, mixed dissolution of citrate and nitrogen-containing small molecules, through evaporation, calcination, etching, to obtain heteroatomized honeycomb carbon;Step S2, mix cobalt salt and heteroatomized honeycomb carbon in a solvent, then add organic ligand to react, after reaction, to obtain metal organic framework / heteroatomized honeycomb carbon nanocomposite;Step S3, place the metal organic framework / heteroatomized honeycomb carbon nanocomposite in a porcelain boat, transfer to a tube furnace for calcination under a preset gas atmosphere, to obtain a heteroatomized honeycomb carbon anchoring high-exposure cobalt / cobalt oxide heterostructure nanocomposite.The above heteroatomized honeycomb carbon anchoring cobalt / cobalt oxide heterostructure nanocomposite has a typical honeycomb morphology and high-exposure cobalt / cobalt oxide heterostructure, and can be used as a high-performance catalytic material.

Description

Technical Field

[0001] This invention belongs to the field of nanocomposite materials, specifically relating to a heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material and its preparation method. Background Technology

[0002] Energy and the environment are crucial foundations and key guarantees for human survival and social development. The massive consumption of traditional fossil fuels (coal, oil, natural gas, etc.) has not only exacerbated the energy crisis but also caused a series of problems such as climate warming and environmental pollution. Faced with the dual challenges of energy shortages and environmental pollution, developing new clean and sustainable energy systems has become crucial for the long-term stable development of human society. Therefore, the development of low-cost, high-energy, and environmentally friendly energy technologies is extremely important. Among these, proton exchange membrane fuel cells and metal-air batteries, represented by zinc-air batteries, have received significant attention due to their environmental friendliness, high energy density, safety, and stability. The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) occurring at the cathodes of fuel cells and metal-air batteries are important processes in the conversion of chemical energy into electrical energy. The ORR and OER reactions are reciprocal processes involving the transfer of multiple electrons and protons, with very slow kinetics and a heavy reliance on the use of precious metals such as Pt, Ir, and Ru. Although noble metal-based catalysts exhibit high catalytic activity, their high cost, scarcity, and poor stability limit their further development and application in novel clean energy devices such as fuel cells and metal-air batteries. Excellent ORR and OER catalysts are crucial for improving the overall performance and efficiency of fuel cells and metal-air battery energy conversion devices. Therefore, developing inexpensive, efficient, and stable non-noble metal catalysts is currently a research hotspot and a key technical challenge.

[0003] Highly exposed active metals supported on porous carbon are a promising type of supported catalyst. Common strategies for preparing porous carbon include hard-template or soft-template methods. These processes often require the pre-preparation of well-defined hard templates (silicon spheres, polystyrene spheres, mesoporous silica, etc.), followed by a series of cumbersome steps such as cross-linking reactions, vacuum infusion, high-temperature carbonization, and acid-base etching to obtain ordered porous carbon. Furthermore, metal-organic frameworks (MOFs) offer abundant metal-organic ligand nodes that can provide numerous metal active sites. However, a key challenge is that the deep embedding of these metal active sites within the carbon framework leads to reduced metal atom utilization and sluggish reaction kinetics. Summary of the Invention

[0004] This invention is made to solve the above-mentioned problems, and aims to provide a heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material and its preparation method.

[0005] This invention provides a method for preparing heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposites, characterized by the following steps:

[0006] Step S1: Citrate and nitrogen-containing small molecules are mixed and dissolved, and then evaporated, calcined and etched to obtain heteroatomized honeycomb carbon;

[0007] Step S2: Cobalt salt and heteroatomized honeycomb carbon are mixed in a solvent, and then an organic ligand is added to react. After the reaction, a metal-organic framework / heteroatomized honeycomb carbon nanocomposite material is obtained.

[0008] Step S3: The metal-organic framework / heteroatomized honeycomb carbon nanocomposite material is placed in a ceramic boat and transferred to a tube furnace for calcination in a preset gas atmosphere to obtain a heteroatomized honeycomb carbon anchored high-exposure cobalt / cobalt oxide heterostructure nanocomposite material.

[0009] The method for preparing heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite materials provided by the present invention may also have the following characteristics: in step S1, the citrate is ammonium citrate, potassium citrate or sodium citrate, and the nitrogen-containing small molecule is urea, dihydrodiamine, melamine or hexamethylenetetramine; in step S1, the molar ratio of citrate to nitrogen-containing small molecule is 0.5 to 5.0.

[0010] The method for preparing heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite materials provided by this invention may also have the following characteristics: In step S1, during evaporation, the evaporation method is an oil bath, water bath, or sand bath, and the temperature is 60℃~150℃.

[0011] In step S1, during calcination, the gas atmosphere is air, nitrogen, or argon, the temperature is 500℃~1000℃, the heating rate is 2℃ / min~20℃ / min, and the calcination time is 0.5h~5h. In step S1, during etching, the acid solution used for etching is hydrochloric acid, sulfuric acid, or nitric acid, the temperature is 20℃~80℃, and the etching time is 10min~60min.

[0012] The method for preparing heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite materials provided by the present invention may also have the following characteristics: in step S2, the cobalt salt is cobalt sulfate heptahydrate, cobalt nitrate hexahydrate, cobalt chloride hexahydrate, cobalt acetate tetrahydrate, or cobalt acetylacetonate; the organic ligand is imidazole, 2-methylimidazolium, 2-ethylimidazolium, or terephthalic acid; and the solvent is deionized water, methanol, ethanol, or N,N-dimethylformamide.

[0013] The method for preparing heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite materials provided by the present invention may also have the following feature: in step S2, the amount of heteroatomized honeycomb carbon used is 10 mg to 200 mg.

[0014] The method for preparing heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite materials provided by the present invention may also have the following feature: in step S2, the molar ratio of cobalt salt to organic ligand is 0.1 to 1.0.

[0015] The method for preparing heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite materials provided by the present invention may also have the following characteristics: in step S2, the reaction temperature is 20℃~80℃ and the reaction time is 1h~8h.

[0016] The preparation method of heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material provided by the present invention may also have the following characteristics: in step S3, the preset gas atmosphere is air, nitrogen or argon atmosphere, the calcination temperature is 500℃~1000℃, the heating rate is 1℃ / min~15℃ / min, and the calcination time is 0.5h~5h.

[0017] The present invention also provides a heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material, which is prepared by the above-mentioned preparation method of the heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material.

[0018] The present invention also provides an application of the above-mentioned heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material as an electrocatalyst.

[0019] The role and effect of invention

[0020] According to the present invention, a method for preparing a heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material is firstly obtained by calcining citrate and nitrogen-containing small molecules using a self-sacrificial pyrolysis strategy, without the need for an additional template, thereby quickly and conveniently obtaining heteroatomized honeycomb carbon. Furthermore, by effectively controlling the size and uniform distribution of metal-organic frameworks on the heteroatomized honeycomb carbon, a highly exposed cobalt / cobalt oxide heterostructure is obtained, thus preparing a heteroatomized honeycomb carbon-anchored highly exposed cobalt / cobalt oxide heterostructure nanocomposite material.

[0021] The self-sacrificial pyrolysis strategy provided by the present invention is more convenient and faster than the traditional hard template or soft template methods. The process is simpler, and product handling is convenient and quicker, making it suitable for preparing non-noble metal (Fe, Ni, Cu, etc.) catalysts with highly exposed active sites. Furthermore, the present invention uses non-noble metal inorganic salts and small organic molecules as synthetic raw materials, which are abundant, resulting in low industrial costs and suitability for medium-scale industrial production.

[0022] Furthermore, the heteroatomic honeycomb carbon-anchored high-exposure cobalt / cobalt oxide heterostructure nanocomposite material prepared by this invention has a typical honeycomb morphology and a high-exposure cobalt / cobalt oxide heterostructure, which can be used as a high-performance catalytic material with excellent performance and good stability. It has broad development prospects and application space in the catalytic conversion of energy and environment. Attached Figure Description

[0023] Figure 1 This is a scanning electron microscope image of the heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material in Example 1 of the present invention;

[0024] Figure 2 This is a transmission electron microscope image of the heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material in Example 1 of the present invention;

[0025] Figure 3 This is a selected area electron diffraction pattern of the heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material in Example 1 of the present invention;

[0026] Figure 4 This is an X-ray diffraction pattern of the heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material in Example 1 of the present invention;

[0027] Figure 5 This is the EDS spectrum of the heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material in Example 1 of the present invention;

[0028] Figure 6 This is the X-ray photoelectron spectrum of the heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material in Example 1 of the present invention;

[0029] Figure 7 This is a graph showing the performance test data of the heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material in Example 1 of the present invention. Detailed Implementation

[0030] To make the technical means, creative features, objectives and effects of the present invention easy to understand, the following embodiments, in conjunction with the accompanying drawings, specifically illustrate the heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material and its preparation method.

[0031] <Example 1>

[0032] This embodiment describes a method for preparing a heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material, comprising the following steps:

[0033] Step S1 involves dissolving citrate and nitrogen-containing small molecules, followed by evaporation, calcination, and etching to obtain heteroatomized honeycomb carbon. The specific process is as follows:

[0034] 30 mmol sodium citrate and 15 mmol urea were mixed and dissolved in 30 mL of water. The solvent was evaporated at 110 °C in an oil bath. The mixture was then ground to obtain a white powder. The white powder was placed in a tube furnace under a nitrogen atmosphere and calcined at 800 °C for 1 h. Excess product was then removed by etching with dilute hydrochloric acid. After filtration, washing with water, and drying, heteroatomized honeycomb carbon was obtained.

[0035] Step S2 involves mixing cobalt salt and heteroatomized honeycomb carbon in a solvent, then adding an organic ligand to react, resulting in a metal-organic framework / heteroatomized honeycomb carbon nanocomposite material. The specific process is as follows:

[0036] 1.0 mmol of cobalt nitrate hexahydrate and 50 mg of heteroatomized honeycomb carbon obtained in step S1 were ultrasonically dispersed in 20 mL of methanol and stirred until uniform. Then, 20 mL of methanol solution containing 4.0 mmol of 2-methylimidazole was added. After reacting at room temperature for 6 h, the mixture was centrifuged and washed with methanol to obtain metal-organic framework / heteroatomized honeycomb carbon nanocomposite material.

[0037] Step S3: The metal-organic framework / heteroatomized honeycomb carbon nanocomposite material is placed in a ceramic boat and transferred to a tube furnace for calcination under a preset gas atmosphere to obtain a heteroatomized honeycomb carbon-anchored high-exposure cobalt / cobalt oxide heterostructure nanocomposite material. The specific process is as follows:

[0038] The metal-organic framework / heteroatomized honeycomb carbon nanocomposite obtained in step S2 was placed in a ceramic boat and transferred to a tube furnace. The heating rate was 2℃ / min, and the mixture was calcined at 700℃ for 2h in a nitrogen atmosphere to obtain a heteroatomized honeycomb carbon anchored high-exposure cobalt / cobalt oxide heterostructure nanocomposite.

[0039] Figure 1 This is a scanning electron microscope image of the heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material in Example 1 of the present invention. Figure 1In the image, (a) is a scanning electron microscope image at 10K magnification, and (b) is a scanning electron microscope image at 50K magnification.

[0040] like Figure 1 As shown, the heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material prepared in this embodiment has a typical honeycomb morphology and a highly exposed cobalt / cobalt oxide heterostructure.

[0041] Figure 2 This is a transmission electron microscope (TEM) image of the heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material in Example 1 of the present invention. Figure 2 (a) is a low-magnification transmission electron microscope (TEM) image, and (b) is a high-resolution TEM image.

[0042] like Figure 2 As shown, the heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material prepared in this embodiment has a distinct cobalt / cobalt oxide heterostructure interface and is uniformly distributed in the form of particles on the heteroatomized honeycomb carbon.

[0043] Figure 3 This is a selected area electron diffraction pattern of the heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material in Example 1 of the present invention.

[0044] like Figure 3 As shown, the heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material prepared in this embodiment has a diffraction crystal form with two phases, cobalt and cobalt oxide.

[0045] Figure 4 This is an X-ray diffraction pattern of the heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material in Example 1 of the present invention.

[0046] like Figure 4 As shown, the heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material prepared in this embodiment has three phase structures: graphite carbon, cobalt, and cobalt oxide.

[0047] Figure 5 This is the EDS spectrum of the heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material in Example 1 of the present invention.

[0048] like Figure 5 As shown, the heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material prepared in this embodiment mainly contains four elements: carbon, nitrogen, oxygen, and cobalt.

[0049] Figure 6 This is the X-ray photoelectron spectrum of the heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material in Example 1 of the present invention. Figure 6(a) is the full X-ray photoelectron spectrum, (b) is the fine X-ray photoelectron spectrum Co2p, (c) is the fine X-ray photoelectron spectrum C1s, (d) is the fine X-ray photoelectron spectrum N1s, and (e) is the fine X-ray photoelectron spectrum O1s.

[0050] like Figure 6 As shown, the heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material prepared in this embodiment mainly contains four elements: carbon, nitrogen, oxygen, and cobalt. Cobalt mainly exists in elemental form and divalent oxide form, corresponding to elemental cobalt and cobalt oxide phases, respectively.

[0051] Figure 7 This is a graph showing the performance test data of the heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material in Example 1 of the present invention. Figure 7 (a) shows the oxygen evolution performance test data, (b) shows the oxygen reduction performance test data, (c) shows the performance test data when applied to liquid zinc-air batteries, and (d) shows the performance test data when applied to flexible all-solid-state zinc-air batteries.

[0052] like Figure 7 As shown, the heteroatomic honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite material prepared in this embodiment has excellent oxygen evolution and oxygen reduction performance, and can also achieve excellent battery performance when used as an electrocatalyst in liquid zinc-air batteries and flexible all-solid-state zinc-air batteries.

[0053] In summary, the preparation method of the heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite of the present invention can successfully prepare heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposite with typical honeycomb morphology and high exposure of cobalt / cobalt oxide heterostructure. This composite material has excellent catalytic activity and stability and can be used as a highly efficient electrocatalyst for oxygen reduction, hydrogen evolution, oxygen evolution, and metal-air battery reactions.

[0054] <Example 2>

[0055] In this embodiment, based on the preparation conditions of Example 1, sodium citrate in step S1 is replaced with potassium citrate, and the other steps are the same as in Example 1, to prepare heteroatomized honeycomb carbon anchored high-exposure cobalt / cobalt oxide heterostructure nanocomposite material.

[0056] <Example 3>

[0057] In this embodiment, based on the preparation conditions of Example 1, urea in step S1 was replaced with melamine, and the other steps were the same as in Example 1, to prepare a heteroatomized honeycomb carbon-anchored high-exposure cobalt / cobalt oxide heterostructure nanocomposite material.

[0058] <Example 4>

[0059] In this embodiment, based on the preparation conditions of Example 1, 15 mmol of urea in step S1 was replaced with 10 mmol of urea, and the other steps were the same as in Example 1, so as to prepare heteroatomized honeycomb carbon anchored high-exposure cobalt / cobalt oxide heterostructure nanocomposite material.

[0060] <Example 5>

[0061] In this embodiment, based on the preparation conditions of Example 1, the dilute hydrochloric acid in step S1 was replaced with dilute sulfuric acid, and the other steps were the same as in Example 1, so as to prepare a heteroatomized honeycomb carbon anchored high-exposure cobalt / cobalt oxide heterostructure nanocomposite material.

[0062] <Example 6>

[0063] In this embodiment, based on the preparation conditions of Example 1, cobalt nitrate hexahydrate in step S2 is replaced with cobalt acetate tetrahydrate, and the other steps are the same as in Example 1, to prepare a heteroatomized honeycomb carbon anchored high-exposure cobalt / cobalt oxide heterostructure nanocomposite material.

[0064] <Example 7>

[0065] In this embodiment, based on the preparation conditions of Example 1, the 1.0 mmol of cobalt nitrate hexahydrate in step S2 was changed to 2.0 mmol of cobalt nitrate hexahydrate, and the other steps were the same as in Example 1, so as to prepare a heteroatomized honeycomb carbon anchored high-exposure cobalt / cobalt oxide heterostructure nanocomposite material.

[0066] <Example 8>

[0067] In this embodiment, based on the preparation conditions of Example 1, 50 mg of heteroatomized honeycomb carbon in step S2 was replaced with 100 mg of heteroatomized honeycomb carbon, and the other steps were the same as in Example 1, so as to prepare a heteroatomized honeycomb carbon anchored high-exposure cobalt / cobalt oxide heterostructure nanocomposite material.

[0068] <Example 9>

[0069] In this embodiment, based on the preparation conditions of Example 1, the calcination at 700°C in step S3 was replaced with calcination at 800°C, and the other steps were the same as in Example 1, thus preparing a heteroatomized honeycomb carbon-anchored high-exposure cobalt / cobalt oxide heterostructure nanocomposite material.

[0070] <Example 10>

[0071] In this embodiment, based on the preparation conditions of Example 1, the heating rate of 2℃ / min in step S3 was replaced with 5℃ / min, and the other steps were the same as in Example 1, so as to prepare a heteroatomized honeycomb carbon anchored high-exposure cobalt / cobalt oxide heterostructure nanocomposite material.

[0072] The role and effect of the embodiments

[0073] As demonstrated in Examples 1-10, the method for preparing heteroatomized honeycomb carbon-anchored cobalt / cobalt oxide heterostructure nanocomposites of the present invention can conveniently and rapidly produce heteroatomized honeycomb carbon-anchored high-exposure cobalt / cobalt oxide heterostructure nanocomposites. This composite material possesses a typical honeycomb morphology and a highly exposed cobalt / cobalt oxide heterostructure, making it suitable as a high-performance catalytic material. It exhibits excellent performance and good stability, and has broad prospects and application potential in catalytic conversion in the energy and environmental fields.

[0074] The above embodiments are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention.

Claims

1. A method for the preparation of a heteroatomized honeycomb carbon anchored high exposure cobalt / cobalt oxide heterostructure nanocomposite, characterized in that, It comprises the following steps: Step S1, mixing and dissolving citrate and nitrogen-containing small molecules, and then evaporating, calcining and etching to obtain a heteroatomized honeycomb carbon, wherein the citrate is sodium, the nitrogen-containing small molecule is urea, and the molar ratio of the citrate to the nitrogen-containing small molecule is 0.5-5.0, When evaporating, the evaporation method is oil bath, water bath or sand bath, and the temperature is 60-150℃, When calcining, the gas atmosphere is air, nitrogen or argon atmosphere, the temperature is 500-1000℃, the heating rate is 2-20℃ / min, and the calcination time is 0.5-5h, When etching, the acid solution used for etching is hydrochloric acid, sulfuric acid or nitric acid, the temperature is 20-80℃, and the etching time is 10-60min; Step S2, mixing cobalt salt and the heteroatomized honeycomb carbon in a solvent, and then adding an organic ligand to react, and obtaining a metal organic framework / heteroatomized honeycomb carbon nanocomposite after reaction, wherein the cobalt salt is cobalt sulfate heptahydrate, the organic ligand is 2-methylimidazole, and the solvent is methanol, The molar ratio of the cobalt salt to the organic ligand is 0.1-1.0, When reacting, the reaction temperature is 20-80℃, and the reaction time is 1-8h; Step S3, placing the metal organic framework / heteroatomized honeycomb carbon nanocomposite in a porcelain boat, transferring to a tube furnace, and calcining under a preset gas atmosphere to obtain a heteroatomized honeycomb carbon anchored high-exposure cobalt / oxidized cobalt heterostructure nanocomposite, wherein the preset gas atmosphere is air, nitrogen or argon atmosphere, the temperature is 500-1000℃ when calcining, the heating rate is 1-15℃ / min, and the calcination time is 0.5-5h.

2. A heteroatomized honeycomb carbon anchored high exposure cobalt / cobalt oxide heterostructure nanocomposite, characterized in that, The heteroatomized honeycomb carbon anchored high-exposure cobalt / oxidized cobalt heterostructure is prepared by the preparation method of claim 1.

3. The heteroatomized honeycomb carbon anchored high-exposure cobalt / oxidized cobalt heterostructure nanocomposite of claim 2 as an electrocatalyst.

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