High-entropy alloy electrode and preparation method and application thereof

Abstract

The application discloses a high-entropy alloy electrode and a preparation method and application thereof. The preparation method of the high-entropy alloy electrode comprises the following steps: step A, providing a soluble metal salt solution containing at least five metal elements, a reducing agent solution and a porous conductive carrier; step B, applying the soluble metal salt solution to the surface of the porous conductive carrier, and allowing the soluble metal salt solution to enter the interior of the porous conductive carrier under suction filtration conditions; step C, continuously maintaining the suction filtration conditions, applying the reducing agent solution to the surface of the porous conductive carrier, and allowing the reducing agent solution to enter the interior of the porous conductive carrier; and step D, repeating steps B to C for several times to obtain the high-entropy alloy electrode. The preparation method provided by the application is simple in operation, low in cost, safe, and free of an acidic plating solution, and is beneficial to large-scale production. In addition, the high-entropy alloy electrode prepared by the method has a very large specific surface area, small high-entropy alloy grains, a stable and uniform plating layer, and can be applied as an electrolytic water anode.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-entropy alloys, in particular to a high-entropy alloy electrode and a preparation method and application thereof. BACKGROUND

[0002] A high-entropy alloy is an alloy formed by five or more than five metals, wherein the atomic fraction of each main element is between 5% and 35%. The high-entropy alloy also has the structural characteristics of occupation disorder and lattice order, which provides a new concept and idea for the design and exploration of new materials. Based on the classic theory of the catalytic field, the Sabatier principle, that is, the adsorption energy of the catalyst surface to the reactant molecules and the key intermediates can be used as the characteristic descriptor of activity, too strong or too weak adsorption energy will lead to the reduction of activity. The unique high-entropy effect of the high-entropy alloy makes the metal composition have a wide range of regulation, which makes it possible to obtain a nearly continuous distribution of adsorption energy curves, so that the adsorption strength of the key intermediates can be optimized by fine-tuning the metal components, thereby achieving the optimization of catalytic activity. In addition, its inherent complex surface also means more active sites. Finally, the "cocktail effect" caused by the uniform mixing of multiple components can effectively enhance the mechanical strength, corrosion resistance and thermal stability of the alloy, providing a guarantee for the catalytic test under severe conditions, and having a wide application prospect in the catalytic field.

[0003] High-temperature smelting is the main method for preparing high-entropy alloys in the industry at present. It mainly involves mixing metal blocks and heating them to a predetermined temperature, keeping them at the temperature to achieve phase equilibrium, and then annealing them to obtain a high-entropy sample. The highest temperature reaches several thousand K, which is a method for many metals to form a high-entropy state. The specific surface area of the high-entropy alloy catalyst or high-entropy alloy electrode prepared by the above method is usually very small (less than 1 m 2 / g), which cannot achieve a better catalytic effect, and the preparation cost is high. The specific surface area of the high-entropy alloy porous electrode is larger, which can achieve a better catalytic effect, but the existing high-entropy alloy porous electrode is usually prepared by electroplating (or electrodeposition) method, which is complex to operate, needs to be powered, has a high cost, and the electroplating solution is an acidic solution, which is not safe and is not conducive to operation. The high-entropy alloy porous electrode prepared by the method has large high-entropy alloy grains.

[0004] Therefore, the prior art still needs to be improved and developed. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a high-entropy alloy electrode and a preparation method and application thereof, aiming to solve the problems of complex operation, high cost and the need for acidic electroplating solution in the existing method for preparing high-entropy alloy electrodes.

[0006] The technical scheme of the present application is as follows:

[0007] In a first aspect, the present application provides a method for preparing a high-entropy alloy electrode, comprising:

[0008] Step A, providing a solution of soluble metal salt containing at least five metal elements, a solution of reducing agent, a porous conductive carrier;

[0009] Step B, applying the solution of soluble metal salt to the surface of the porous conductive carrier, and allowing the solution of soluble metal salt to enter the interior of the porous conductive carrier under suction filtration conditions;

[0010] Step C, continuing to maintain the suction filtration conditions, and applying the solution of reducing agent to the surface of the porous conductive carrier, so that the solution of reducing agent enters the interior of the porous conductive carrier;

[0011] Step D, repeating steps B to C for several times to obtain the high-entropy alloy electrode.

[0012] Optionally, the metals in the solution of soluble metal salt are selected from at least five of Ni, Fe, Co, Mo, Mn, V, Cu, Zn, Pt, Ir, Ru, Au, Ag, and Rh.

[0013] Optionally, the solution of soluble metal salt is selected from at least one of metal sulfate, metal chloride, and metal acetate.

[0014] Optionally, the reducing agent in the solution of reducing agent is selected from at least one of sodium borohydride and potassium borohydride.

[0015] Optionally, before step B, the method further comprises a step of:

[0016] providing a polar solvent;

[0017] applying the polar solvent to the surface of the porous conductive carrier, and allowing the polar solvent to enter the interior of the porous conductive carrier under suction filtration conditions, so as to wet the inner and outer surfaces of the porous conductive carrier.

[0018] Optionally, the polar solvent is selected from at least one of water, methanol, ethanol, propanol, and acetone.

[0019] Optionally, the porous conductive carrier is selected from one of foamed nickel and foamed copper.

[0020] In a second aspect, the present application provides a high-entropy alloy electrode prepared by the method as described above.

[0021] In a third aspect, the present application provides the use of the high-entropy alloy electrode as described above in electrolysis of water.

[0022] Optionally, the high-entropy alloy electrode is applied as an oxygen evolution anode for electrolysis of water.

[0023] Beneficial effects: The high-entropy alloy electrode (high-entropy alloy plated electrode) is prepared by direct chemical plating of a soluble metal salt solution and a reducing agent solution at room temperature, without heating. Unlike traditional chemical plating, the plating piece does not need to be continuously immersed in the plating solution, and unlike chemical plating, the surface is required to be rough, not smooth, so that the prepared high-entropy alloy electrode has a very large specific surface area, and does not need to use stabilizers and surfactants. Compared with existing electroplating methods, the preparation method provided by the present application is simple to operate, low in cost, safe, and conducive to large-scale production, and the prepared high-entropy alloy electrode has a very large specific surface area, small high-entropy alloy grains, a stable and uniform plating layer, and can be applied as an electrolysis water anode. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 FIG. 1 is a schematic diagram of the preparation process of the high-entropy alloy electrode in the embodiment of the present application.

[0025] Figure 2 FIG. 2 is an element distribution diagram of the high-entropy alloy powder, wherein (a) is a SEM diagram, (b) is a distribution diagram of the Ru element in the corresponding region of the SEM diagram in (a), (c) is a distribution diagram of the Ni element in the corresponding region of the SEM diagram in (a), (d) is a distribution diagram of the Ir element in the corresponding region of the SEM diagram in (a), (e) is a distribution diagram of the Co element in the corresponding region of the SEM diagram in (a), and (f) is a distribution diagram of the Fe element in the corresponding region of the SEM diagram.

[0026] Figure 3 FIG. 3 is a powder X-ray diffraction diagram of the high-entropy alloy powder.

[0027] Figure 4 FIG. 4 is a scanning electron microscope diagram of the high-entropy alloy electrode prepared in Example 1 of the present application.

[0028] Figure 5 FIG. 5 is a high-resolution transmission electron microscope diagram of the high-entropy alloy electrode prepared in Example 1 of the present application.

[0029] Figure 6 FIG. 6 is a linear voltammetry curve of the high-entropy alloy electrode prepared in Example 1 of the present application for electrolysis of 1M KOH solution.

[0030] Figure 7 FIG. 7 is a Tafel slope result diagram of the high-entropy alloy electrode prepared in Example 1 of the present application.

[0031] Figure 8 FIG. 8 is a stability test result diagram of the high-entropy alloy electrode prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0032] The present application provides a high-entropy alloy electrode and a preparation method and application thereof. To make the purpose, technical solutions and effects of the present application clearer and more explicit, the present application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application.

[0034] At present, a high-entropy alloy porous electrode with a large specific surface area is generally prepared by electroplating (or electrodeposition), but this operation is complex, requires power supply, has high cost, and the electroplating solution is an acidic solution, which is not safe and is not conducive to operation. The high-entropy alloy porous electrode prepared has large high-entropy alloy grains. Based on this, the present application provides a preparation method of a high-entropy alloy electrode, which comprises:

[0035] Step A, providing a soluble metal salt solution containing at least five metal elements, a reducing agent solution, and a porous conductive carrier;

[0036] Step B, applying the soluble metal salt solution to the surface of the porous conductive carrier, and allowing the soluble metal salt solution to enter the interior of the porous conductive carrier under suction filtration conditions;

[0037] Step C, continuing to maintain the suction filtration conditions, and applying the reducing agent solution to the surface of the porous conductive carrier, so that the reducing agent solution enters the interior of the porous conductive carrier;

[0038] Step D, repeating steps B to C for several times to obtain the high-entropy alloy electrode.

[0039] The electroless plating method is to use a mixed plating solution of a strong reducing agent, a stabilizer and a surfactant to slowly reduce metal ions on the surface of a plating part to form a plating layer without electricity. However, the plating layer prepared by the above method is relatively slow, and the conventional plating layer requires to be flat and non-porous, so that a stable metal or P, B and the like plating layer can be obtained to change the surface properties of the plating part. The present application uses the filter-aided electroless plating technology to directly react the soluble metal salt solution and the reducing agent solution on the surface and inside of the porous conductive carrier at room temperature to deposit high-entropy alloy in situ without heating. Unlike the traditional electroless plating, the plating part does not need to be continuously immersed in the plating solution, and unlike the electroless plating, the surface does not need to be flat but rough (i.e. the preparation method of the high-entropy alloy is a reverse operation compared with the traditional electroless plating method), and no stabilizer and surfactant are used, so that a high-entropy alloy electrode with a very large surface area is obtained. Compared with the existing electroplating method, the preparation method provided by the present application is simple in operation, low in cost, safe, and conducive to large-scale production, and the prepared high-entropy alloy electrode has a very high specific surface area (up to 90 m 2 / g), small high-entropy alloy grain, stable and uniform plating layer, and can be applied as an electrolytic water anode.

[0040] Specifically, the soluble metal salt solution is applied to the surface of the porous conductive carrier, and the soluble metal salt solution enters the inside of the porous conductive carrier under the filter-aided condition; the filter-aided condition is continuously maintained, the reducing agent solution is applied to the surface of the porous conductive carrier, and the reducing agent solution enters the inside of the porous conductive carrier, reacts with the soluble metal salt solution in the process of entering the inside of the porous conductive carrier, releases gas, reduces metal ions, and quickly forms a black plating layer; then the soluble metal salt solution and the reducing agent solution are repeatedly applied alternately, and the two react until the porous conductive carrier is completely black.

[0041] In one embodiment of step A, the metal in the soluble metal salt is selected from at least five of Ni, Fe, Co, Mo, Mn, V, Cu, Zn, Pt, Ir, Ru, Au, Ag and Rh. For example, the metal in the soluble metal salt is selected from Ni, Fe, Co, Mo and Mn; the metal in the soluble metal salt is selected from Fe, Co, Mo, Mn, Zn and Cu; the metal in the soluble metal salt is selected from Ni, Co, Mo, Mn, V and Cu; the metal in the soluble metal salt is selected from Ni, Fe, Co, Mo, Ru, Au, Ag and Rh, etc.

[0042] In one embodiment, the soluble metal salt is selected from at least one of metal sulfate, metal chloride, metal acetate. As an example, when the metal in the soluble metal salt is selected from Ni, Fe, Co, Mo, Mn, the soluble metal salt in the soluble metal salt solution is selected from nickel sulfate, iron sulfate, cobalt sulfate, molybdenum sulfate, manganese sulfate, when the metal in the soluble metal salt is selected from Ni, Fe, Co, Mo, Mn, the soluble metal salt in the soluble metal salt solution is selected from nickel sulfate, iron chloride, cobalt sulfate, molybdenum sulfate, manganese sulfate, when the metal in the soluble metal salt is selected from Fe, Co, Mo, Mn, Zn, Cu, the soluble metal salt in the soluble metal salt solution is selected from iron chloride, cobalt acetate, molybdenum sulfate, manganese sulfate, zinc sulfate, copper acetate.

[0043] In one embodiment, the soluble metal salt solution is prepared by adding the soluble metal into the first solvent.

[0044] In further embodiments, the first solvent is selected from water, but not limited thereto.

[0045] In further embodiments, the first solvent is selected from deionized water.

[0046] In one embodiment, the reducing agent in the reducing agent solution is selected from at least one of sodium borohydride (NaBH4), potassium borohydride (KBH4), but not limited thereto.

[0047] In one embodiment, the reducing agent solution is prepared by adding the reducing agent into the second solvent.

[0048] In further embodiments, the second solvent is selected from water, but not limited thereto.

[0049] In further embodiments, the second solvent is selected from deionized water.

[0050] In one embodiment, the porous conductive carrier is selected from one of nickel foam, copper foam, but not limited thereto. The porous conductive carrier in this embodiment can be purchased directly, or can be prepared by etching a corresponding metal block to roughen and porous it.

[0051] In one embodiment, before the step B, further comprising a step of:

[0052] providing a polar solvent;

[0053] The polar solvent is applied to the surface of the porous conductive carrier, and under the condition of suction filtration, the polar solvent enters the interior of the porous conductive carrier, and the inner surface and the outer surface of the porous conductive carrier are wetted. The wetting of the porous conductive carrier is more conducive to the operation of subsequent steps C and D, and is more conducive to the preparation of the high-entropy alloy electrode.

[0054] In an implementation, the polar solvent is at least one selected from water, methanol, ethanol, propanol, and acetone, but is not limited thereto.

[0055] In step B, the soluble metal salt solution is applied to the surface of the porous conductive carrier, and under the condition of suction filtration, the soluble metal salt solution enters the interior of the porous conductive carrier. Specifically, the porous conductive carrier can be placed on a suction filtration device for suction filtration, and an organic filter membrane is placed between the porous carrier and the suction filtration device. The organic filter membrane includes, but is not limited to, a nylon microporous filter membrane, a vinylidene fluoride resin membrane, and a polyvinylidene fluoride membrane.

[0056] The embodiment of the present application also provides a high-entropy alloy electrode prepared by the preparation method of the present application as described above. In the embodiment, the high-entropy alloy electrode includes a porous conductive carrier and a high-entropy alloy loaded in the interior and on the surface of the porous conductive carrier.

[0057] The embodiment of the present application also provides an application of the high-entropy alloy electrode as described above in the electrolysis of water. In the embodiment, the high-entropy alloy electrode has a lower overpotential, a lower Tafel slope, and a higher stability.

[0058] In an implementation, the high-entropy alloy electrode is applied as an oxygen evolution anode for the electrolysis of water.

[0059] The following will be described in detail through specific embodiments.

[0060] Embodiment 1

[0061] The preparation method of the high-entropy alloy electrode, as shown in the formula (I), includes the following steps: Figure 1

[0062] (1) 800 mg of nickel acetate tetrahydrate, 800 mg of cobalt acetate hexahydrate, 400 mg of iridium chloride, 400 mg of ruthenium chloride, and 165 mg of ferrous acetate anhydrous are added to 50 mL of deionized water, mixed uniformly, and prepared into a nickel-cobalt-iridium-iron-ruthenium mixed solution A;

[0063] (2) 2968 mg of sodium borohydride is added to 80 mL of deionized water, mixed uniformly, and prepared into a sodium borohydride solution B;

[0064] ​(3) Take a piece of foam nickel with the size of 1 cm x 2 cm x 1 mm, clean it with acetone, deionized water and dilute hydrochloric acid in sequence until it is clean, then place it on the assembled filtration equipment, and pad a polyvinylidene fluoride film under the foam nickel;

[0065] (4) Under the filtration condition, add deionized water to the surface of the foam nickel to wet the inner and outer surfaces of the foam nickel;

[0066] (5) Then, add the nickel-cobalt-iridium-iron-ruthenium mixed solution A to the surface of the foam nickel at room temperature, so that the surface of the foam nickel is fully covered with the nickel-cobalt-iridium-iron-ruthenium mixed solution A, then perform filtration to make the nickel-cobalt-iridium-iron-ruthenium mixed solution A enter the inside of the foam nickel, and continue to maintain the filtration condition to add the sodium borohydride solution B to the surface of the foam nickel (the reaction is immediately carried out and hydrogen is released, and the formation of the black coating is observed), and perform filtration until there is no obvious droplet on the surface;

[0067] (6) At room temperature, repeat steps (4) to (5) to alternately add the nickel-cobalt-iridium-iron-ruthenium mixed solution A and the sodium borohydride solution B to the foam nickel until the foam nickel is completely plated to become black, wash it with deionized water, prepare the high-entropy alloy electrode, and then store the obtained high-entropy alloy electrode in acetone.

[0068] Based on the need for element distribution testing, the method of Example 1 is used, except that no foam nickel is added, and the high-entropy alloy powder is directly reduced to perform element distribution testing, and the results are shown in Figure 2 . Wherein (a) is a SEM image, (b) is a distribution map of the Ru element in the corresponding area of the SEM image, (c) is a distribution map of the Ni element in the corresponding area of the SEM image, (d) is a distribution map of the Ir element in the corresponding area of the SEM image, (e) is a distribution map of the Co element in the corresponding area of the SEM image, and (f) is a distribution map of the Fe element in the corresponding area of the SEM image. It can be seen that the particle size of the high-entropy alloy particles is less than 3 nm, and there are five elements of Ru, Ni, Ir, Co and Fe.

[0069] Based on the need for powder X-ray diffraction (XRD) testing, the method of Example 1 is used, except that no foam nickel is added, and the high-entropy alloy powder is directly reduced to perform XRD testing, and the results are shown in Figure 3 . It can be seen that the high-entropy alloy powder has a face-centered cubic (111) crystal plane.

[0070] The scanning electron microscope (SEM) image of the high-entropy alloy electrode prepared in Example 1 is shown in Figure 4 . It can be seen that it has a porous structure.

[0071] The high-resolution transmission electron microscope (HRTEM) image of the high-entropy alloy electrode prepared in Example 1 is shown in Figure 5As shown, lattice fringes can be clearly seen.

[0072] The high-entropy alloy electrode prepared in Example 1 was used as an anode working electrode, an Ag / AgCl electrode was used as a reference electrode, and a platinum metal sheet with a length x width x thickness of 1 cm x 2 cm x 0.1 mm was used as a cathode counter electrode. The electrocatalytic oxygen evolution reaction was carried out in a 1M KOH solution, and the linear voltammetry curve (scanning from high voltage to low voltage) is as shown in Figure 6 As shown, it can be seen that the 10mA / cm 2 has a lower overpotential of only 220mV. At the same time, the measured Tafel slope is as shown in Figure 7 The Tafel slope is 49mV / dec.

[0073] The high-entropy alloy electrode prepared in Example 1 was subjected to a simulated industrial catalytic (strong alkaline solution 1MKOH) stability test, and the results are as shown in Figure 8 As shown, the potential value remained unchanged for up to 100 hours, and the electrode had sufficient stability.

[0074] Example 2

[0075] The preparation method of the high-entropy alloy electrode comprises the following steps:

[0076] (1) 800mg of nickel acetate tetrahydrate, 800mg of copper acetate monohydrate, 400mg of iridium chloride, 400mg of ruthenium chloride and 165mg of ferrous acetate anhydrous were added to 50mL of deionized water, mixed uniformly to prepare a nickel-copper-iridium-iron-ruthenium mixed solution A;

[0077] (2) 2968mg of sodium borohydride was added to 80mL of deionized water, mixed uniformly to prepare a sodium borohydride solution B;

[0078] (3) A piece of foamed nickel with a length x width x thickness of 1cm x 2cm x 1mm was taken, and then cleaned with acetone, deionized water and dilute hydrochloric acid until clean. Then it was placed on the assembled filtration equipment, and a polyvinylidene fluoride film was placed under the foamed nickel;

[0079] (4) Under the condition of suction filtration, deionized water was added to the surface of the foamed nickel to wet the inner and outer surfaces of the foamed nickel;

[0080] (5) Then, the surface of the foamed nickel was added with the nickel-copper-iridium-iron-ruthenium mixed solution A at room temperature, so that the surface of the foamed nickel was fully covered with the nickel-copper-iridium-iron-ruthenium mixed solution A. Then, the nickel-copper-iridium-iron-ruthenium mixed solution A was allowed to enter the interior of the foamed nickel by suction filtration until there were no obvious droplets on the surface. The suction filtration condition was continued, and the sodium borohydride solution B was added to the surface of the foamed nickel (the reaction was immediately carried out and hydrogen was released, and the formation of the black plating layer was observed). The suction filtration was continued until there were no obvious droplets on the surface.

[0081] (6) At room temperature, repeat steps (4) to (5) to alternately drop nickel-copper-iridium-iron-ruthenium mixed solution A and sodium borohydride solution B onto the foamed nickel until the foamed nickel is completely plated to become black, washed with deionized water to prepare a high-entropy alloy electrode, and then the obtained high-entropy alloy electrode is stored in acetone.

[0082] In summary, the present application provides a high-entropy alloy electrode and a preparation method and application thereof. The present application directly prepares a high-entropy alloy electrode (high-entropy alloy plated layer electrode) by using a soluble metal salt solution and a reducing agent solution at room temperature without heating. Unlike traditional chemical plating, the present application does not require the plating piece to be continuously immersed in the plating solution, and unlike chemical plating, the present application does not require a smooth surface, but requires a surface roughness, so that the prepared high-entropy alloy electrode has a very large specific surface area, and does not use stabilizers and surfactants. Compared with existing electroplating methods, the preparation method provided by the present application is simple to operate, low in cost, safe, and does not require an acidic plating solution, which is conducive to large-scale production. The prepared high-entropy alloy electrode has a very large specific surface area, small high-entropy alloy grains, a stable and uniform plating layer.

[0083] It should be understood that the application of the present application is not limited to the above examples, and those skilled in the art can make improvements or changes according to the above description, and all these improvements and changes shall belong to the protection scope of the appended claims of the present application.

Claims

1. A method for preparing a high-entropy alloy electrode, characterized by, Comprising: Step A, providing a solution of soluble metal salt containing at least five metal elements, a solution of reducing agent, a porous conductive carrier; Step B, applying the solution of soluble metal salt to the surface of the porous conductive carrier, allowing the solution of soluble metal salt to enter the interior of the porous conductive carrier under suction filtration conditions; Step C, continuing to maintain suction filtration conditions, applying the solution of reducing agent to the surface of the porous conductive carrier, allowing the solution of reducing agent to enter the interior of the porous conductive carrier; Step D, repeating steps B to C for several times to obtain the high-entropy alloy electrode; Before the step B, further comprising steps of: Providing a polar solvent; Applying the polar solvent to the surface of the porous conductive carrier, allowing the polar solvent to enter the interior of the porous conductive carrier under suction filtration conditions, wetting the inner and outer surfaces of the porous conductive carrier; The metal in the soluble metal salt is selected from at least five of Ni, Fe, Co, Mo, Mn, V, Cu, Zn, Pt, Ir, Ru, Au, Ag, and Rh.

2. The method of claim 1, wherein the high-entropy alloy electrode is prepared by a process comprising: The soluble metal salt is selected from at least one of metal sulfate, metal chloride, and metal acetate.

3. The method of claim 1, wherein the high-entropy alloy electrode is prepared by a process comprising: The reducing agent in the solution of reducing agent is selected from at least one of sodium borohydride and potassium borohydride.

4. The method of claim 1, wherein the high-entropy alloy electrode is prepared by a process comprising: The polar solvent is selected from at least one of water, methanol, ethanol, propanol, and acetone.

5. The method of claim 1, wherein the high-entropy alloy electrode is prepared by a process comprising: The porous conductive carrier is selected from one of foamed nickel and foamed copper.

6. A high-entropy alloy electrode, characterized by, Prepared by the preparation method of any one of claims 1-5.

7. The high-entropy alloy electrode of claim 6 for use in electrolysis of water.

8. Use according to claim 7, characterized in that, The high-entropy alloy electrode is used as an oxygen evolution anode for electrolysis of water.

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