Monatomic monolithic electrode based on cobalt-nickel-iron ternary and preparation method and application thereof

Abstract

The invention belongs to the technical field of electrochemical materials, and particularly relates to a cobalt-nickel-iron ternary monatomic monolithic electrode and a preparation method and application thereof. The preparation method comprises the following steps: preparing cobalt-nickel-iron precursor solutions respectively, coating the cobalt-nickel-iron precursor solutions on the front and back surfaces of foamed nickel, and further performing high-temperature calcination in a hydrogen-argon mixed gas atmosphere to form a catalyst which is anchored on a three-dimensional porous foamed nickel substrate and has cobalt-nickel-iron ternary monatomic atoms, and the catalyst is used as an anode for hydrogen production by electrolysis of water for oxygen evolution (OER) reaction. According to the synthesis method, use of an insulating binder is avoided, excellent electron transmission capacity is ensured, electrolyte infiltration and rapid release of oxygen bubbles are greatly promoted through the three-dimensional porous structure, the synergistic electron effect of multi-element metal, the maximum atom utilization efficiency and an ideal mass transmission channel are combined, and the performance of the material is improved. And a solution with great application potential is provided for developing an efficient and low-cost water electrolysis hydrogen production anode.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electrochemical materials. More particularly, it relates to a cobalt-nickel-iron ternary monatomic monolithic electrode and a preparation method and application thereof. BACKGROUND

[0002] With the transformation of global energy structure and the promotion of the "double carbon" target, hydrogen energy, as a clean and efficient secondary energy, is receiving increasingly widespread attention. Electrolytic water hydrogen production is a multi-electron transfer reaction, which has slow kinetics and high overpotential, seriously restricting the conversion efficiency and economy. Therefore, developing electrode materials with high activity, high stability and low cost has become the core issue in the field of electrocatalysis.

[0003] OER is a complex process involving four electron transfers, with slow kinetics and high overpotential required to drive the reaction, which directly leads to a large amount of electrical energy loss. Therefore, developing efficient and stable OER catalysts to reduce the reaction energy barrier and overpotential is a key link to reduce the energy consumption of electrolytic water and improve the efficiency of hydrogen production. Noble metal-based catalysts (such as IrO2, RuO2) are considered as benchmark catalysts for OER, showing excellent activity. However, their high cost, extremely limited natural reserves and poor long-term stability seriously hinder their widespread application in large-scale industrial devices. Abundant and low-cost transition metal (such as Fe, Co, Ni) based materials have attracted the attention of researchers. Among them, nickel-iron (NiFe) and cobalt-iron (CoFe) based catalysts have shown excellent performance comparable to or even better than noble metal catalysts in alkaline environments, which is mainly due to the synergistic effect of the adjustment of the electronic structure between different metal elements, which optimizes the adsorption energy of the reaction intermediates.

[0004] However, traditional transition metal-based catalysts still face several severe challenges. First, the most common powder catalyst must use a polymer binder (such as Nafion) to fix it on the surface of the current collector (such as nickel foam, carbon paper) during electrode preparation. These insulating binders will block the active sites of the catalyst, increase the interface contact resistance, and cause the catalyst to fall off from the substrate after a long time of operation, thereby significantly deteriorating the conductivity and structural stability of the electrode. Second, although nanostructured catalysts provide a higher specific surface area, many atoms inside are not exposed on the surface to participate in the reaction, and the atom utilization rate is low. A large number of bulk atoms are wasted, making it difficult to achieve a leap in the overall mass activity of the catalyst.

[0005] To address these challenges, two frontiers have emerged: one is to construct self-supported electrodes, i.e., to grow active materials directly on conductive substrates to form integrated structures, thereby completely abandoning binders; the other is to develop single-atom catalysts, i.e., to anchor metal active sites on supports in the form of atomic dispersion, thereby achieving nearly 100% atom utilization and exhibiting unique electronic structures and extremely high intrinsic activity.

[0006] In summary, the cobalt-nickel-iron ternary single-atom monolithic electrode developed by the present application not only breaks through the bottleneck of traditional catalysts in terms of material design, but also provides a high-efficiency, stable and low-cost OER electrode preparation strategy from the perspective of engineering application, thereby providing a valuable reference path for promoting the industrialization process of water electrolysis hydrogen production technology. SUMMARY

[0007] The technical problem to be solved by the present application is to overcome the defects and deficiencies of high energy consumption, single active site and weak electrode construction strength in the prior art, and to provide a cobalt-nickel-iron ternary single-atom monolithic electrode, a preparation method and application thereof. The present application first prepares a cobalt-nickel-iron precursor solution, coats it on both sides of a nickel foam, and further forms a catalyst with cobalt-nickel-iron ternary single atoms anchored on a three-dimensional porous nickel foam substrate by high-temperature calcination in a hydrogen-argon mixed gas atmosphere, which is used as a water electrolysis hydrogen anode for oxygen evolution (OER) reaction. This synthesis method not only avoids the use of insulating binders, ensuring excellent electronic transmission capability, but also greatly promotes electrolyte infiltration and rapid release of oxygen bubbles due to the three-dimensional porous structure, thereby combining the synergistic electronic effect of multi-metal, maximum atom utilization efficiency and ideal mass transfer channel, and providing an extremely application-potential solution for developing a high-efficiency, low-cost water electrolysis hydrogen anode.

[0008] The present application aims to provide a preparation method of a cobalt-nickel-iron ternary single-atom monolithic electrode.

[0009] Another object of the present application is to provide a cobalt-nickel-iron ternary single-atom monolithic electrode.

[0010] Another object of the present application is to provide an application of a cobalt-nickel-iron ternary single-atom monolithic electrode as an anode for water electrolysis hydrogen production in an alkaline solution.

[0011] The above objects of the present application are achieved by the following technical solutions: A preparation method of a cobalt-nickel-iron ternary single-atom monolithic electrode, the preparation method comprising the following steps: 1) Dissolve cobalt salt, nickel salt and iron salt in a solvent to prepare a cobalt-nickel-iron precursor solution; 2) Uniformly coat the cobalt-nickel-iron precursor solution obtained in step 1) on both sides of a nickel foam, and place it in an oven for drying; 3) Place the nickel foam obtained in step 2) in a vacuum box furnace and anneal it at high temperature to obtain a ternary single-atom integral electrode of iron, cobalt and nickel.

[0012] Preferably, in step (1), the iron salt is at least one of ferric nitrate, ferric chloride, and ferric acetate; the cobalt salt is at least one of cobalt nitrate, cobalt chloride, and cobalt acetate; the nickel salt is at least one of nickel nitrate, nickel chloride, and nickel acetate; and the solvent is anhydrous ethanol.

[0013] Preferably, in step (1), the mass ratio of the cobalt salt, nickel salt, and iron salt is 1.5~2.5:0.5~1.5:1, and the total concentration of metal ions in the cobalt-nickel-iron precursor solution is 4 mg / mL. More preferably, in step (1), the mass ratio of the cobalt salt, nickel salt, and iron salt is 2:1:1.

[0014] Preferably, in step (2), the drying temperature is 50~70℃ and the drying time is 20~40 minutes.

[0015] Preferably, in step (2), the loading of nickel foam on both sides is 1.5~2.5 mg / cm². 2 .

[0016] Preferably, in step (3), the high-temperature annealing process is annealing at 350~450℃ for 2.5~3.5 hours, and the annealing atmosphere is a hydrogen-argon mixture, wherein the volume ratio of hydrogen to argon is 1:19.

[0017] Preferably, in step (1), the foamed nickel is cleaned as follows before use: the foamed nickel is first placed in 1 M hydrochloric acid and ultrasonically treated for 5-10 minutes, rinsed with ultrapure water, and then the commercial nickel felt is ultrasonically treated in acetone, anhydrous ethanol and ultrapure water for 5-10 minutes each, and finally taken out and air-dried.

[0018] The cobalt-nickel-iron ternary single-atom monolithic electrode was prepared based on the preparation method described above.

[0019] The cobalt-nickel-iron ternary single-atom monolithic electrode prepared as described above is used as an anode to achieve hydrogen production through water electrolysis in alkaline solution.

[0020] The present invention has the following beneficial effects: The method of this invention is simple to prepare a self-supporting monolithic electrode with cobalt-nickel-iron ternary single atoms anchored on a three-dimensional porous nickel foam substrate, and is suitable for industrial production. The monolithic cobalt-nickel-iron ternary single-atom electrode prepared by the method of the present invention loads atomically dispersed cobalt, nickel, and iron single atoms, and utilizes their multi-element synergistic effect to further optimize the electronic structure and form multiple active sites; The method of this invention utilizes the excellent three-dimensional conductive network and macroscopic porous structure of nickel foam to ensure high-speed electron transport, full wetting of electrolyte, and rapid escape of oxygen bubbles from the reaction product, thus solving the problems of mass transfer and conductivity. The method of this invention constructs atomically dispersed active sites by etching the surface of nickel foam and calcining it at high temperature in a reducing atmosphere, thereby maximizing the utilization of metal atoms. The method of this invention allows for the mass production of self-supporting monolithic electrodes made of cobalt, nickel, and iron ternary single atoms, which can be directly integrated into existing water electrolysis hydrogen production systems and used as highly efficient oxygen evolution anodes. Attached Figure Description

[0021] Figure 1 This is a comparison chart of the OER reaction performance of the cobalt-nickel-iron ternary single-atom monolithic electrode prepared in Example 1 with that of Comparative Examples 1, 2, and 3. Figure 2 This is the OER reaction stability diagram of the cobalt-nickel-iron ternary single-atom monolithic electrode prepared in Example 1; Figure 3 This is a diagram showing the total water splitting performance of Example 1 as the anode and commercial Pt / C as the cathode; Figure 4 This is a stability performance diagram of the anion exchange membrane water electrolysis device assembled with Example 1 as the anode. Detailed Implementation

[0022] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0023] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0024] Example 1 A method for preparing a ternary single-atom monolithic electrode based on iron, cobalt, and nickel, the method comprising the following steps: (1) Nickel foam (specific surface area of ​​500 m²) 2 / g, thickness of 1 mm, porosity of 97%) Before use, the following cleaning treatment should be performed: First, place the nickel foam in 1 mol / L hydrochloric acid and sonicate for 10 minutes. After rinsing with ultrapure water, sonicate the nickel foam in acetone, anhydrous ethanol and ultrapure water for 5 minutes each. Take it out and let it air dry. Cut it into 1 cm * 1.5 cm pieces of nickel foam. (2) Weigh cobalt chloride, nickel nitrate and ferric sulfate respectively and dissolve them in 1.5 ml of anhydrous ethanol at a mass ratio of 2:1:1 to obtain a total ion concentration of 4 mg / mL. Sonicate until the solution is homogeneous and clear to obtain a cobalt-nickel-iron precursor solution. (3) The cobalt-nickel-iron precursor solution obtained in step (2) is uniformly coated on both sides of the nickel foam obtained in step (1), with the metal atom loading on both sides being 2 mg / cm³. 2 Place it in a hot air dryer and dry it at 60°C for 30 minutes; (4) Place the nickel foam obtained in step (3) in a vacuum box furnace, introduce a hydrogen-argon mixture (volume ratio of hydrogen to argon 1:19) into the vacuum box furnace for 30 minutes to ensure that the furnace is filled with the hydrogen-argon mixture, raise the temperature to 400°C at a rate of 5°C / min and hold for 3 hours, and wait for the reaction to cool to room temperature to obtain the cobalt-iron-nickel ternary single-atom catalyst self-supporting electrode material.

[0025] Comparative Example 1 Comparative Example 1 is the catalyst prepared in Example 1 through steps 1), 2), and 3). In step (2), the cobalt, nickel, and iron precursor solution is adjusted to a cobalt and nickel precursor solution with a mass ratio of 2:1. The loading on both sides is the same as in Example 1.

[0026] Comparative Example 2 Comparative Example 2 is the catalyst prepared in Example 1 through steps 1), 2), and 3). In step 1), the cobalt, nickel, and iron precursor solution was adjusted to a cobalt and iron precursor solution with a mass ratio of 2:1. The loading on both sides was the same as in Example 1.

[0027] Comparative Example 3 Comparative Example 3 is the catalyst prepared in Example 1 through steps 1), 2), and 3). In step 1), the cobalt, nickel, and iron precursor solution was adjusted to a nickel and iron precursor solution with a mass ratio of 1:1, and the loading on both sides was the same as in Example 1.

[0028] Test methods OER performance tests were conducted on Examples 1, 1, 2, and 3 respectively. An electrolytic cell was selected as the container, the test sample as the working electrode, a platinum wire as the auxiliary electrode, an Ag / AgCl electrode as the reference electrode, and a 1 M KOH solution as the electrolyte. The tests were performed using an electrochemical workstation. All voltage ranges mentioned in this article are relative to the reversible hydrogen electrode (RHE).

[0029] OER performance test conditions: Temperature: room temperature; LSV scan rate: 10 mV / s; LSV test voltage range: 0 ~ 2.0V.

[0030] OER stability test conditions: Temperature: room temperature; Current density: 1 A / cm² 2 Test duration: 100 hours.

[0031] The comparison results after testing under the above methods and conditions are as follows: Figure 1 and Figure 2 As shown in the figure, the self-supported electrode of the cobalt-iron-nickel ternary single-atom catalyst exhibits excellent OER catalytic performance and stability at a current density of 1 A / cm². 2 The potential was 1.56 V, significantly better than the other comparative examples, and at a current density of 1 A / cm². 2 The electrode performance did not change significantly after 100 h of OER reaction.

[0032] Using Example 1 as the anode and commercial nickel felt loaded with commercial Pt / C as the cathode, an assembly was formed with an area of ​​1 cm². 2 In the water electrolysis device, at 1 A / cm 2 At a current density of 1 A / cm², the voltage is only 1.59 V, demonstrating excellent water electrolysis performance. 2 Even after operating at a high constant current density for more than 100 hours, the performance can still be maintained.

[0033] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a cobalt-nickel-iron ternary single-atom monolithic electrode, characterized in that, The preparation method includes the following steps: 1) Dissolve cobalt salt, nickel salt and iron salt in a solvent to prepare a cobalt-nickel-iron precursor solution; 2) Coat both sides of the nickel foam uniformly with the cobalt-nickel-iron precursor solution obtained in step 1), and place it in an oven to dry; 3) Place the nickel foam obtained in step 2) in a vacuum box furnace and anneal it at high temperature to obtain a ternary single-atom integral electrode of iron, cobalt and nickel.

2. The method for preparing the cobalt-nickel-iron ternary single-atom monolithic electrode according to claim 1, characterized in that: In step (1), the iron salt is at least one of ferric nitrate, ferric chloride, and ferric acetate; the cobalt salt is at least one of cobalt nitrate, cobalt chloride, and cobalt acetate; the nickel salt is at least one of nickel nitrate, nickel chloride, and nickel acetate; and the solvent is anhydrous ethanol.

3. The method for preparing the cobalt-nickel-iron ternary single-atom monolithic electrode according to claim 1, characterized in that, In step (1), the mass ratio of the cobalt salt, nickel salt and iron salt is 1.5~2.5:0.5~1.5:1, and the total concentration of metal ions in the cobalt-nickel-iron precursor solution is 4 mg / mL.

4. The method for preparing the cobalt-nickel-iron ternary single-atom monolithic electrode according to claim 1, characterized in that, In step (1), the mass ratio of the cobalt salt, nickel salt and iron salt is 2:1:

1.

5. The method for preparing the cobalt-nickel-iron ternary single-atom monolithic electrode according to claim 1, characterized in that, In step (2), the drying temperature is 50~70℃ and the drying time is 20~40 minutes.

6. The method for preparing the cobalt-nickel-iron ternary single-atom monolithic electrode according to claim 1, characterized in that, In step (2), the loading of nickel foam on both sides is 1.5~2.5 mg / cm². 2 .

7. The method for preparing the cobalt-nickel-iron ternary single-atom monolithic electrode according to claim 1, characterized in that, In step (3), the high-temperature annealing process is to anneal at 350~450℃ for 2.5~3.5 hours, and the annealing atmosphere is a hydrogen-argon mixture, wherein the volume ratio of hydrogen to argon is 1:

19.

8. The method for preparing the cobalt-nickel-iron ternary single-atom monolithic electrode according to claim 1, characterized in that, In step (1), the foamed nickel is cleaned as follows before use: the foamed nickel is first placed in 1 M hydrochloric acid and ultrasonically treated for 5-10 minutes, then rinsed with ultrapure water, and then the commercial nickel felt is ultrasonically treated in acetone, anhydrous ethanol and ultrapure water for 5-10 minutes each, and finally taken out and air-dried.

9. A cobalt-nickel-iron ternary single-atom monolithic electrode prepared by the preparation method according to any one of claims 1-8.

10. The cobalt-nickel-iron ternary single-atom monolithic electrode prepared according to claim 9 is used as an anode to achieve hydrogen production by water electrolysis in alkaline solution.

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