A self-assembled CoSe2 / NiSe2 composite nano-heterostructure electrocatalyst material, a preparation method and application thereof

Abstract

The application belongs to the field of oxygen evolution electrocatalytic materials, and particularly relates to a self-assembled CoSe2 / NiSe2 composite nano-heterostructure electrocatalyst material and a preparation method and application thereof. The application obtains a mixed solution by dissolving cobalt acetate, trisodium citrate and a surfactant in a mixed solvent of water and DMSO, adds an aqueous solution of K2[Ni(CN)4] into the mixed solution, stirs and ages for 4 hours, extracts the precipitate with water and anhydrous ethanol, centrifugalizes, and air-dries to obtain a two-dimensional orthogonal self-assembled precursor CoNi(CN)4 nanosheet. The nanosheet is subjected to selenization heat treatment to obtain the CoSe2 / NiSe2 composite nano-heterostructure material. The application synthesizes the orthogonal self-assembled nanosheet precursor in one step by a liquid phase method, the nanosheet has a regular morphology and a small size, has a high specific surface area, a fast electron transmission path and a certain structural stability, is subjected to selenization heat treatment to obtain the CoSe2 / NiSe2 composite nano-heterostructure material, and retains the orthogonal self-assembled morphology, and has a wide application prospect in water electrolysis oxygen evolution reaction and material morphology design.

Description

Technical Field

[0001] This invention belongs to the field of oxygen evolution electrocatalytic materials, specifically relating to the preparation method and application of a two-dimensional orthogonal self-assembled cobalt diselenide / nickel diselenide nano-heterostructure material with high stability and high efficiency in electrocatalyzing oxygen evolution reaction. Background Technology

[0002] With continuous economic development, environmental and energy problems are becoming increasingly serious. To address the urgent need for clean and sustainable energy, water electrolysis for hydrogen production is a novel and environmentally friendly method for producing high-quality hydrogen. However, because the oxygen evolution reaction in water electrolysis is a slow electrochemical process involving the transfer of four electrons, water electrolysis for oxygen and hydrogen production often suffers from high energy consumption and low efficiency. Therefore, developing efficient and stable oxygen evolution electrocatalysts is crucial for reducing activation barriers, accelerating the reaction, and thus improving energy conversion efficiency and lifespan.

[0003] According to research reports, noble metal-based materials such as RuO2 and IrO2 generally possess excellent electrocatalytic performance, but their widespread application is often limited by resource reserves and cost. Therefore, it is essential to design a highly active and low-cost electrocatalyst from the perspective of structure-activity relationship and heterostructure. It has been reported that due to the stronger conductivity of Se atoms, a large number of metal selenides can serve as electrocatalysts for the oxygen evolution reaction, such as CoSe2 and NiSe2, which exhibit excellent electrocatalytic activity. This invention utilizes the layered structure of Hoffmann-type materials and employs a novel method of interlayer solvent extraction to prepare precursors with different morphologies. Then, through selenization heat treatment, metal selenide electrocatalysts that largely retain the morphology of the precursors can be obtained. This invention provides a new approach for the subsequent rational design and derivation of transition metal-based composite nano-heterostructure electrocatalysts. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of the prior art and provide a novel, efficient and inexpensive oxygen evolution electrocatalyst with a two-dimensional orthogonal self-assembled CoSe2 / NiSe2 composite nano-heterostructure, its preparation method and application, and also introduces a novel method for controlling the morphology of material self-assembly.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] This invention provides a method for preparing an orthogonally self-assembled cobalt diselenide / nickel diselenide composite nano-heterostructure electrocatalyst, comprising the following steps:

[0007] (1) Cobalt acetate, trisodium citrate, and surfactant are dissolved in a solvent, wherein the solvent is a mixture of water and DMSO, to obtain a mixed solution; K2[Ni(CN)4] is dissolved in water to obtain a K2[Ni(CN)4] solution; the K2[Ni(CN)4] solution is added to the aforementioned mixed solution, stirred, and aged at room temperature for 4 hours. The growth time of nanomaterials affects the morphology. If the time is too long, they may become thicker or larger, or some may dissolve and become hollow. The precipitate obtained after aging is washed and extracted with pure water and anhydrous ethanol, centrifuged, and air-dried to obtain two-dimensional orthogonal self-assembled precursor CoNi(CN)4 nanosheets;

[0008] The surfactant is preferably polyvinylpyrrolidone (PVP);

[0009] In the mixed solution, the volume ratio of water to DMSO is preferably 2:1;

[0010] In the mixed solution, the concentration of cobalt acetate is preferably 0.01–0.05 mmol / mL, the concentration of trisodium citrate is preferably 0.03–0.07 mmol / mL, the concentration of surfactant is preferably 0.01–0.04 g / mL, and the water is preferably deionized water;

[0011] The concentration of the K2[Ni(CN)4] solution is preferably 0.05–0.1 mmol / mL, and the solvent is preferably deionized water;

[0012] The preferred volume ratio of the K2[Ni(CN)4] solution to the mixed solution is 20:45;

[0013] In this invention, the solvent is a mixture of water and DMSO, which causes the morphology to transform into tetragonal shapes. Using pure water for interlayer extraction can produce orthogonal self-assembled morphologies. Anhydrous ethanol is used to further wash away excess water and facilitate drying.

[0014] The preferred room temperature is 15℃-40℃;

[0015] (2) Selenium powder and precursor CoNi(CN)4 nanosheet material were placed in the upper and lower vents of an atmosphere tube furnace, respectively, and heated to 350℃~500℃ at a rate of 1~10℃ / min under a protective atmosphere. The temperature was then maintained for calcination for 2~5h to obtain the CoSe2 / NiSe2 composite nanoheterostructure material.

[0016] The protective atmosphere during calcination is preferably one or a combination of nitrogen and argon in any proportion.

[0017] The preferred mass ratio of selenium powder to precursor CoNi(CN)4 material is 1 to 8:1.

[0018] The preparation method provided by this invention can prepare two-dimensional orthogonally self-assembled CoSe2 / NiSe2 composite nano-heterostructure electrocatalyst materials, and at the same time provides a novel morphology design method that can be realized in some Hoffmann-type materials, which further broadens the research ideas and directions in this field.

[0019] The present invention also provides a two-dimensional orthogonal self-assembled CoSe2 / NiSe2 composite nano-heterostructure electrocatalyst material prepared by any of the above preparation methods.

[0020] The two-dimensional orthogonal self-packed cobalt diselenide / nickel diselenide composite nano-heterostructure electrocatalyst material prepared by the above preparation method of the present invention can be used in the oxygen evolution reaction of water electrolysis.

[0021] The CoSe2 / NiSe2 material with a two-dimensional orthogonal self-assembled morphology prepared by this invention has the following advantages compared with existing materials and technologies:

[0022] (1) This invention enables the one-step synthesis of orthogonally self-assembled nanosheet precursors via a simple liquid-phase method. The orthogonally assembled two-dimensional material has a regular morphology and small size, consisting of small hexagonal sheets approximately 900 nm long and 300 nm wide that self-assemble into square sheets approximately 5 μm long (see Appendix for details). Figure 1 CoSe2, with its high specific surface area, fast electron transport path, and certain structural stability, serves as a good precursor template. After subsequent selenization heat treatment, CoSe2 / NiSe2 composite nano-heterostructure materials can be obtained. The orthogonal self-assembly morphology of the precursor is preserved through heat treatment under appropriate conditions. In the OER process, the high specific surface area and heterostructure provide more and more effective active sites, accelerating the rate of ion diffusion and electron conduction, thereby accelerating the reaction kinetics of electrocatalytic oxygen evolution.

[0023] (2) The material of the present invention belongs to non-precious metal electrocatalysts. While reducing costs, it has high catalytic activity and stability for oxygen evolution reaction. It also provides a special morphology design method, which has broad application prospects in water electrolysis oxygen evolution reaction and material morphology design. Attached Figure Description

[0024] Figure 1 These are a) SEM, b) XRD, and c) EDS images of the CoNi(CN)4 nanosheets prepared in Example 1.

[0025] Figure 2 The images shown are a) SEM, b) XRD, and c) EDS images of the CoSe2 / NiSe2 composite nanoheterostructure material prepared in Example 1.

[0026] Figure 3This is an HRTEM image of the CoSe2 / NiSe2 composite nanoheterostructure material prepared in Example 1.

[0027] Figure 4 These are the XRD patterns of CoSe2 / NiSe2 composite nano-heterostructure materials prepared at different heat treatment temperatures in Examples 1-4: a) 350℃, b) 400℃, c) 450℃, d) 500℃.

[0028] Figure 5 The images show the LSV diagrams of the precursors in Examples 1-4 and the CoSe2 / NiSe2 composite nano-heterostructures prepared at different heat treatment temperatures; a) CoNi(CN)4 precursor, b) 500℃, c) 400℃, d) 350℃, e) 450℃.

[0029] Figure 6 These are SEM images of the precursor material CoNi(CN)4 obtained after different washing and extraction methods in Examples 5-7; a) Precursor of Example 5, b) Precursor of Example 6 was washed and extracted with pure water and ethanol was used to wash away residual water, c) Precursor of Example 7 was first extracted with pure water and then extracted with DMSO.

[0030] Figure 7 The images show the XRD patterns of the precursor materials CoNi(CN)4 obtained by different washing and extraction methods in Examples 5-7; a) the precursor of Example 5, b) the precursor of Example 6 was washed and extracted with pure water and ethanol was used to wash away residual water, c) the precursor of Example 7 was first extracted with pure water and then extracted with DMSO.

[0031] Figure 8 These are FTIR images of the precursor material CoNi(CN)4 obtained after different washing and extraction methods in Examples 5-7; a) DMSO solvent, b) Precursor of Example 5, c) Precursor of Example 6 was washed and extracted with pure water and anhydrous ethanol was used to remove residual water, d) Precursor of Example 7 was first extracted with pure water and then extracted with DMSO. Detailed Implementation

[0032] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings, but the scope of protection of the present invention is not limited thereto.

[0033] Example 1

[0034] 1.5 mmol cobalt acetate, 2.3 mmol trisodium citrate, and 1.0 g PVP (molecular weight 40000) were dissolved in a mixed solvent of 30 ml water and 15 ml DMSO, and the solution was magnetically stirred to form a transparent solution A. K2[Ni(CN)4] was dissolved in 20 ml deionized water to obtain solution B. Solution B was then slowly poured into solution A over 5 seconds, and the mixture was stirred for 3 minutes. The mixture was then aged at room temperature for 4 hours. The resulting precipitate was washed twice with pure water, and finally washed with anhydrous ethanol to remove residual water. After centrifugation and air drying at room temperature, a cube about 5 μm long was obtained, which was the precursor CoNi(CN)4 powder, formed by the orthogonal self-assembly of small hexagonal sheets about 900 nm long and 300 nm wide. 20 mg of CoNi(CN)4 powder was weighed into a ceramic boat and placed in a small atmosphere tube furnace (HF-Kejing). The lower vent of OTF-1200X-S (hereinafter the same) and 120mg selenium powder in another ceramic boat were placed in the upper vent of an atmosphere tube furnace. The furnace was heated to 450℃ at a rate of 2℃ / min under an argon atmosphere and held for 4h to obtain the target product CoSe2 / NiSe2 with a size and morphology basically consistent with the precursor.

[0035] Example 2

[0036] 1.5 mmol cobalt acetate, 2.3 mmol trisodium citrate, and 1.0 g PVP (molecular weight 40000) were dissolved in a mixed solvent of 30 ml water and 15 ml DMSO, and the solution was magnetically stirred to form a transparent solution A. K2[Ni(CN)4] was dissolved in 20 ml deionized water to obtain solution B. Solution B was then slowly poured into solution A over 5 seconds, and the mixture was stirred for 3 minutes. The mixture was then aged at room temperature for 4 hours. The precipitate was washed twice with pure water and extracted. Finally, residual water was washed away with anhydrous ethanol, centrifuged, and air-dried at room temperature to obtain the two-dimensional orthogonal self-assembled precursor CoNi(CN)4 powder. 20 mg of CoNi(CN)4 powder was weighed into a ceramic boat and placed in a small atmosphere tube furnace (HF-Kejing). The lower vent of OTF-1200X-S (hereinafter the same) and 120mg selenium powder in another ceramic boat were placed in the upper vent of an atmosphere tube furnace. The furnace was heated to 350℃ at a rate of 2℃ / min under an argon atmosphere and held for 4h to obtain the target product CoSe2 / NiSe2.

[0037] Example 3

[0038] 1.5 mmol cobalt acetate, 2.3 mmol trisodium citrate, and 1.0 g PVP (molecular weight 40000) were dissolved in a mixed solvent of 30 ml water and 15 ml DMSO, and the solution was magnetically stirred to form a transparent solution A. K2[Ni(CN)4] was dissolved in 20 ml deionized water to obtain solution B. Solution B was then slowly poured into solution A over 5 seconds, and the mixture was stirred for 3 minutes. The mixture was then aged at room temperature for 4 hours. The precipitate was washed twice with pure water and extracted. Finally, residual water was washed away with anhydrous ethanol, centrifuged, and air-dried at room temperature to obtain the two-dimensional orthogonal self-assembled precursor CoNi(CN)4 powder. 20 mg of CoNi(CN)4 powder was weighed into a ceramic boat and placed in a small atmosphere tube furnace (HF-Kejing). The lower vent of OTF-1200X-S (hereinafter the same) and 120mg selenium powder in another ceramic boat were placed in the upper vent of an atmosphere tube furnace. The furnace was heated to 400℃ at a rate of 2℃ / min under an argon atmosphere and held for 4h to obtain the target product CoSe2 / NiSe2.

[0039] Example 4

[0040] 1.5 mmol cobalt acetate, 2.3 mmol trisodium citrate, and 1.0 g PVP (molecular weight 40000) were dissolved in a mixed solvent of 30 ml water and 15 ml DMSO, and the solution was magnetically stirred to form a transparent solution A. K2[Ni(CN)4] was dissolved in 20 ml deionized water to obtain solution B. Solution B was then slowly poured into solution A over 5 seconds, and the mixture was stirred for 3 minutes. The mixture was then aged at room temperature for 4 hours. The precipitate was washed twice with pure water and extracted. Finally, residual water was washed away with anhydrous ethanol, centrifuged, and air-dried at room temperature to obtain the two-dimensional orthogonal self-assembled precursor CoNi(CN)4 powder. 20 mg of CoNi(CN)4 powder was weighed into a ceramic boat and placed in a small atmosphere tube furnace (HF-Kejing). The lower vent of OTF-1200X-S (hereinafter the same) and 120mg selenium powder in another ceramic boat were placed in the upper vent of an atmosphere tube furnace. The furnace was heated to 500℃ at a rate of 2℃ / min under an argon atmosphere and held for 4h to obtain the target product CoSe2 / NiSe2.

[0041] Example 5

[0042] 1.5 mmol cobalt acetate, 2.3 mmol trisodium citrate, and 1.0 g PVP (molecular weight 40000) were dissolved in a mixed solvent of 30 ml water and 15 ml DMSO and magnetically stirred to form a transparent solution A. K2[Ni(CN)4] was dissolved in 20 ml deionized water to obtain solution B. Solution B was then slowly poured into solution A over 5 seconds and stirred for 3 minutes. The mixed solution was then aged at room temperature for 4 hours. The resulting precipitate was not washed, but centrifuged and air-dried at room temperature to obtain the two-dimensional orthogonal self-assembled precursor CoNi(CN)4 powder.

[0043] Example 6

[0044] 1.5 mmol cobalt acetate, 2.3 mmol trisodium citrate, and 1.0 g PVP (molecular weight 40000) were dissolved in a mixed solvent of 30 ml water and 15 ml DMSO and magnetically stirred to form a transparent solution A. K2[Ni(CN)4] was dissolved in 20 ml deionized water to obtain solution B. Solution B was then slowly poured into solution A over 5 seconds and stirred for 3 minutes. The mixed solution was then aged at room temperature for 4 hours. The resulting precipitate was washed and extracted twice with pure water. Finally, residual water was washed away with anhydrous ethanol, centrifuged, and air-dried at room temperature to obtain the two-dimensional orthogonal self-assembled precursor CoNi(CN)4 powder.

[0045] Example 7

[0046] 1.5 mmol cobalt acetate, 2.3 mmol trisodium citrate, and 1.0 g PVP (molecular weight 40000) were dissolved in a mixed solvent of 30 ml water and 15 ml DMSO and magnetically stirred to form a transparent solution A. K2[Ni(CN)4] was dissolved in 20 ml deionized water to obtain solution B. Solution B was then slowly poured into solution A over 5 seconds and stirred for 3 minutes. The mixed solution was then aged at room temperature for 4 hours. The precipitate was washed and extracted twice with pure water, then washed and extracted twice with DMSO, centrifuged, and air-dried at room temperature to obtain the two-dimensional orthogonal self-assembled precursor CoNi(CN)4 powder.

[0047] Experimental Example 1: Precursor Morphology Regulation

[0048] From the appendix Figure 6The SEM images show that morphology control can be achieved by extracting the interlayer molecules of the Hoffmann-type two-dimensional material using different solvents. Specifically: a) When the precursor is extracted without washing and centrifuged directly, the precursor is a smooth cubic plate. b) When the precursor is washed with pure water and then washed with anhydrous ethanol to remove residual water from the precursor surface, a cubic plate formed by orthogonal self-assembly of small hexagonal lamellae using the precursor cubic plate as a template is obtained. c) When the precursor is first washed with pure water and then extracted with DMSO, a cubic plate formed by self-assembly of small cubic lamellae using the precursor cubic plate as a template is obtained. (See attached image.) Figure 7 The XRD pattern shows that a significant phase transformation occurred in the material during the extraction of the precursor, combined with the attached... Figure 8 The FTIR spectra show that interlayer molecular exchange occurred during the extraction of the precursor. This demonstrates that H₂O and DSMO molecules can mutually extract from each other within the interlayer structure of Hoffmann-type materials, achieving guest molecule exchange and further initiating phase transitions, thus affecting the material's morphology. Therefore, this invention can control the entry and exit of interlayer molecules to regulate the generation of new phases, thereby enabling refined morphology design of materials. This has significant implications for the future refined morphology and structural design of nanomaterials.

[0049] Experiment Example 2 Performance Test

[0050] The precursor product CoNi(CN)4 in Example 1 and the subsequent products CoSe2 / NiSe2 from Examples 1-4, which were heat-treated at different temperatures, were used as working electrodes, Pt wire as counter electrodes, and Hg / HgO electrodes as reference electrodes. A three-electrode system was tested using a rotating disk electrode with a 1 mol / L potassium hydroxide (KOH) solution as the electrolyte and a rotation speed of 1600 rpm. The relevant performance tests, such as LSV, CV, EIS, and stability, were performed.

[0051] The performance test results are as follows:

[0052] Electrodes made from the precursor product CoNi(CN)4 in Example 1 and the subsequent product CoSe2 / NiSe2 from Examples 1-4, which were heat-treated at different temperatures, were subjected to LSV testing at a scan rate of 5 mV s⁻¹ and at 10 mA cm⁻¹. -2 The corresponding overpotentials at the given current densities are 395mV, 409mV, 429mV, and 450mV. However, the overpotentials of the precursor are much larger due to conductivity issues.

[0053] The material of this invention belongs to the category of transition metal-based electrocatalysts. While reducing costs, it has high electrocatalytic oxygen evolution reaction activity. Furthermore, the novel interlayer solvent extraction method can realize the morphology control and design of this series of materials. The preparation process is simple, so it has broad application prospects in the fields of electrocatalysis and micro / nano morphology control.

[0054] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Other variations and modifications may be made without departing from the technical solutions described in the claims.

Claims

1. A preparation method of a self-assembled CoSe2 / NiSe2 composite nano-heterostructure electrocatalyst material, characterized in that, The preparation method comprises the following steps: (1) dissolving cobalt acetate, trisodium citrate and a surfactant in a solvent, wherein the solvent is a mixed solvent of water and DMSO, to obtain a mixed solution, wherein the volume ratio of water to DMSO in the mixed solution is 2:1; dissolving K2[Ni(CN)4] in water to obtain a K2[Ni(CN)4] solution; adding the K2[Ni(CN)4] solution into the mixed solution, stirring and then aging at room temperature for 4 hours, washing and extracting the obtained precipitate with pure water and anhydrous ethanol, centrifuging, and air-drying to obtain a two-dimensional orthogonal self-assembled precursor CoNi(CN)4 nanosheet, wherein the washing and extracting process is specifically interlayer extraction with pure water to generate an orthogonal self-assembled morphology; The anhydrous ethanol is used to further wash away excess water; (2) placing selenium powder and the precursor CoNi(CN)4 nanosheet material at the upper and lower air vents of an atmospheric tube furnace, respectively, and heating at a rate of 1-10 ℃ / min to 350-500 ℃ under a protective atmosphere, and then performing heat treatment and calcination for 2-5 hours to obtain the CoSe2 / NiSe2 composite nano-heterostructure electrocatalyst material.

2. The method for preparing a self-assembled CoSe2 / NiSe2 composite nano-heterostructure electrocatalyst material according to claim 1, characterized in that, The surfactant is polyvinylpyrrolidone.

3. The method for preparing a self-assembled CoSe2 / NiSe2 composite nano-heterostructure electrocatalyst material according to claim 1, characterized in that, In the mixed solution, the concentration of cobalt acetate is 0.01-0.05 mmol / mL, the concentration of trisodium citrate is 0.03-0.07 mmol / mL, and the concentration of the surfactant is 0.01-0.04 g / mL.

4. The method for preparing a self-assembled CoSe2 / NiSe2 composite nano-heterostructure electrocatalyst material according to claim 1, characterized in that, The concentration of the K2[Ni(CN)4] solution is 0.05-0.1 mmol / mL.

5. The method for preparing a self-assembled CoSe2 / NiSe2 composite nano-heterostructure electrocatalyst material according to claim 1, characterized in that, The volume ratio of the K2[Ni(CN)4] solution to the mixed solution is 20:

45.

6. The method for preparing a self-assembled CoSe2 / NiSe2 composite nano-heterostructure electrocatalyst material according to claim 1, characterized in that, The mass ratio of the selenium powder to the precursor CoNi(CN)4 material is 1-8:

1.

7. The method for preparing a self-assembled CoSe2 / NiSe2 composite nano-heterostructure electrocatalyst material according to claim 1, characterized in that, The protective atmosphere is one of nitrogen and argon or a combination of the two in any ratio.

8. The self-assembled CoSe2 / NiSe2 composite nano-heterostructure electrocatalyst material prepared by the preparation method in any one of claims 1-7.

9. Application of the self-assembled CoSe2 / NiSe2 composite nano-heterostructure electrocatalyst material in claim 8 in an electrolytic water oxygen evolution reaction.

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