CN112609213B - High-entropy alloy porous electrode and preparation method thereof - Google Patents

High-entropy alloy porous electrode and preparation method thereof Download PDF

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CN112609213B
CN112609213B CN202011452837.1A CN202011452837A CN112609213B CN 112609213 B CN112609213 B CN 112609213B CN 202011452837 A CN202011452837 A CN 202011452837A CN 112609213 B CN112609213 B CN 112609213B
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entropy alloy
electrode
conductive substrate
hydrogen
ions
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CN112609213A (en
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李松
秦高梧
王雨楠
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Northeastern University China
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    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/56—Electroplating: Baths therefor from solutions of alloys
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
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    • C25B1/04—Hydrogen or oxygen by electrolysis of water
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/003—Electroplating using gases, e.g. pressure influence
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis

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Abstract

The invention discloses a high-entropy alloy porous electrode and a preparation method thereof, wherein the preparation method of the high-entropy alloy porous electrode comprises the following steps: step S10: preparing a mixed solution containing a plurality of metal ions and hydrogen ions; step S30: and (3) taking the mixed solution obtained in the step (S10) as an electrolyte, taking a conductive substrate as a cathode, and carrying out electrodeposition under a negative potential, wherein the negative potential is lower than the reduction potential of the hydrogen ions, and when the plurality of metal ions are reduced and deposited on the conductive substrate, the hydrogen ions are synchronously reduced on the surface of the conductive substrate to form hydrogen bubbles so as to obtain the high-entropy alloy electrode with a porous structure. The electrode prepared by the method is a high-entropy alloy electrode with a porous structure, is simple and efficient, can be used for large-scale preparation, and has universality. The electrode has a large specific surface area and shows high-efficiency electrocatalysis performance in the hydrogen production reaction by water electrolysis.

Description

High-entropy alloy porous electrode and preparation method thereof
Technical Field
The invention relates to the technical field of electrode materials, in particular to a high-entropy alloy porous electrode and a preparation method thereof.
Background
Theoretical calculation and experiments prove that the activity of the catalyst in the electrocatalysis process is directly related to the adsorption strength of the surface of the catalyst on key reactants. For the transition metal catalyst, the d-charge electronic structure directly determines the adsorption strength of intermediate species, and further determines the quality of the catalytic performance of the transition metal catalyst. In recent years, alloying has become an effective means for controlling electronic structures. Most of the existing transition metal alloy catalysts are based on one main element, and the high-entropy alloy is composed of four or more metal elements with little difference in content. Due to the unique high entropy effect, a plurality of metal atoms are randomly arranged, the chemical atom environment around the active center is completely different from that of the traditional alloy material, and high activity and selectivity are possible to obtain. In addition, the different atom sizes among various atoms often bring larger lattice distortion, so that a larger strain effect is generated, and the electronic structure of the electronic structure is further regulated and controlled. Therefore, the high-entropy alloy is expected to become a high-efficiency electrocatalyst.
However, the traditional high-entropy alloy is mainly prepared by an alloy smelting method, and the obtained high-entropy alloy has a small specific surface area, is not beneficial to playing a catalytic function and limits the application of the high-entropy alloy in the field of electrocatalysis. In the existing synthesis method, the dealloying method is easy to cause the damage of the material structure, and the fast heating synthesis method has extremely high requirements on equipment and operation conditions and is not beneficial to large-scale production.
Disclosure of Invention
The main object of the present invention is to provide a high entropy alloy porous electrode and a method for preparing the same, in order to overcome the above problems or at least partially solve the above problems.
According to one aspect of the invention, a preparation method of a high-entropy alloy porous alloy electrode is provided, which comprises the following steps: step S10: preparing a mixed solution containing a plurality of metal ions and hydrogen ions, wherein the plurality of metal ions comprise at least four metal ions; step S30: and (4) taking the mixed solution obtained in the step (S10) as an electrolyte, taking the conductive substrate as a cathode, and carrying out electrodeposition under a negative potential, wherein the negative potential is lower than the reduction potential of hydrogen ions, and when a plurality of metal ions are reduced and deposited on the conductive substrate, the hydrogen ions are synchronously reduced on the surface of the conductive substrate to form hydrogen bubbles so as to obtain the high-entropy alloy electrode with a porous structure.
In some embodiments, the plurality of metal ions includes at least five metal ions, such that the high entropy alloy electrode material is at least a quinary high entropy alloy electrode.
In some embodiments, in step S10, the hydrogen ion source and the plurality of metal sources are dissolved in water to form a mixed solution.
In some embodiments, in step S10, the hydrogen ion source is an acid solution.
In some embodiments, the acid solution comprises at least one of concentrated hydrochloric acid, concentrated nitric acid, and concentrated sulfuric acid.
In some embodiments, in step S10, the hydrogen ion concentration in the mixed solution is 0.01-2 mol/L.
In some embodiments, in step S10, the plurality of metal sources are a plurality of transition metal salts.
In some embodiments, the plurality of metal sources comprises at least five of a chromium salt, an iron salt, a nickel salt, a cobalt salt, a manganese salt, a zinc salt, a copper salt, or a platinum salt, such that the high entropy alloy electrode is at least a quinary high entropy alloy electrode.
In some embodiments, in step S30, the electrodeposition is direct current electrodeposition.
In some embodiments, in step S30, the electrodeposition current density is 0.8-10A/cm 2 The deposition time of the electrodeposition is at least 10 seconds.
In some embodiments, the conductive matrix comprises a carbon paper, copper mesh, or a foamed nickel matrix.
In some embodiments, the method further comprises step S20: pretreating the conductive substrate to remove surface contaminants; the sequence of step S10 and step S20 is not fixed.
In some embodiments, in step S30, the electrodeposition employs a graphite electrode as the counter electrode.
According to another aspect of the invention, a high-entropy alloy porous electrode is provided, and is prepared by the preparation method in the above embodiment.
According to the technical scheme, a high-entropy alloy electrode with a porous structure is prepared by a simple electrodeposition method, under the drive of a large enough reduction potential, various metal ions can be uniformly deposited on a conductive substrate without selection to form an alloy, meanwhile, hydrogen ions are reduced on the surface of the conductive substrate to form hydrogen bubbles, and the alloy can form a porous structure under the assistance of the hydrogen bubbles, so that the high-entropy alloy porous electrode is prepared; the electro-deposition method is simple and efficient, does not damage the structure of the high-entropy alloy electrode material like an alloy removing method, has universality, and is simple in required equipment and operation conditions and beneficial to large-scale preparation. The high-entropy alloy porous electrode has a large specific surface area, can be applied to the hydrogen production reaction by electrolyzing water, and shows excellent electrocatalysis performance.
Drawings
Other objects and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings, and may assist in a comprehensive understanding of the invention.
FIG. 1 is a flow chart of a method for preparing a high-entropy alloy porous electrode according to an embodiment of the invention;
FIG. 2 is a detailed flowchart of the step S10 in the preparation method of FIG. 1;
FIG. 3 is an electron microscope photograph of a high-entropy alloy porous electrode according to example 1 of the present invention, wherein FIG. 3(a) is a low-power scanning electron microscope photograph, FIG. 3(b) is a high-power scanning electron microscope photograph, and FIG. 3(c) is a high-resolution transmission electron microscope photograph;
FIG. 4 is a graph of the element content of the high-entropy alloy porous electrode according to example 1 of the present invention;
FIG. 5 is a polarization curve diagram of the high-entropy alloy porous electrode applied to the hydrogen production reaction by water electrolysis according to the embodiment 1 of the invention;
FIG. 6 is a Tafel plot of the high-entropy alloy porous electrode applied to a water electrolysis hydrogen production reaction according to example 1 of the invention;
FIG. 7 is an electron microscope photograph of a high-entropy alloy porous electrode according to example 2 of the present invention, wherein FIG. 7(a) is a low-power scanning electron microscope photograph, FIG. 7(b) is a high-power scanning electron microscope photograph, and FIG. 7(c) is a high-resolution transmission electron microscope photograph;
FIG. 8 is a graph of the element content of the high-entropy alloy porous electrode according to example 2 of the present invention;
FIG. 9 is a polarization curve diagram of the high-entropy alloy porous electrode applied to the water electrolysis hydrogen production reaction according to the embodiment 2 of the invention;
FIG. 10 is a Tafel plot of the application of the high-entropy alloy porous electrode in the hydrogen production reaction by water electrolysis according to example 2 of the present invention;
FIG. 11 is an electron microscope photograph of a high-entropy alloy porous electrode according to example 3 of the present invention, wherein FIG. 11(a) is a low-power scanning electron microscope photograph, FIG. 11(b) is a high-power scanning electron microscope photograph, and FIG. 11(c) is a high-resolution transmission electron microscope photograph;
FIG. 12 is a graph of the element content of the high-entropy alloy porous electrode according to example 3 of the present invention;
FIG. 13 is a polarization curve diagram of the high-entropy alloy porous electrode applied to the hydrogen production reaction by water electrolysis according to the embodiment 3 of the invention;
FIG. 14 is a Tafel plot of the high-entropy alloy porous electrode applied to a water electrolysis hydrogen production reaction according to the embodiment 3 of the invention.
It is noted that the drawings are not necessarily to scale and are merely illustrative in nature and not intended to obscure the reader.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention. It should be apparent that the described embodiment is one embodiment of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention.
Unless defined otherwise, technical or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
According to an embodiment of the present invention, there is provided a method for preparing a high-entropy alloy porous electrode, as shown in fig. 1, including steps S10 to S30, specifically as follows:
step S10: preparing a mixed solution containing a plurality of metal ions and hydrogen ions. In this embodiment, the plurality of metal ions includes at least four metal ions to prepare the high-entropy alloy electrode. It should be noted that the preparation method in this embodiment may also be applied to prepare other alloy materials, for example, the plurality of metal ions may include three metal ions, so as to obtain a ternary alloy electrode material. As shown in fig. 2, the step S10 of preparing the mixed solution includes:
step S11: fully dissolving a plurality of metal sources in water to form a metal ion aqueous solution;
step S12: and adding a hydrogen ion source into the aqueous solution of the metal ions to form a mixed solution.
The method of preparing the mixed solution is not limited to this, and a plurality of metal ion sources and a plurality of hydrogen ion sources may be dissolved in water to form a plurality of metal ions and hydrogen ions in the solution. For example, the source of hydrogen ions may be diluted with water and the various metal sources may be added to dissolve them sufficiently to form a mixed solution. It is understood that the water used to formulate the mixed solution is deionized water to prevent the introduction of other impurities.
In this embodiment, in step S10, the hydrogen ion source used in preparing the mixed solution is an acid solution including at least one of concentrated hydrochloric acid, concentrated nitric acid, and concentrated sulfuric acid. It is understood that in other embodiments, the species of the hydrogen ion source is not limited thereto, and may include other compounds capable of generating hydrogen ions in an aqueous solution, such as perchloric acid and the like.
In this embodiment, the metal source used in preparing the mixed solution is a transition metal salt, and the transition metal salt can be dissolved in the acid solution to generate metal ions. Specifically, the transition metal salt used in the present embodiment includes at least five of chromium trichloride hexahydrate, ferrous chloride tetrahydrate, nickel chloride hexahydrate, cobalt chloride hexahydrate, manganese chloride tetrahydrate, zinc chloride, copper chloride dihydrate and platinum tetrachloride, so that the resulting high-entropy alloy electrode is at least a quinary high-entropy alloy.
It should be noted that the various metal sources used in this embodiment are all metal hydrochlorides, and since the anions in the electrolyte do not affect the electrodeposition process of the metal ions, in other embodiments, other types of salts of metals, such as copper sulfate, zinc nitrate, etc., may be used. In addition, the multiple metal sources used in the embodiment comprise at least five of chromium salts, iron salts, nickel salts, cobalt salts, manganese salts, zinc salts, copper salts or platinum salts, and in other embodiments, the multiple metal sources used can comprise metal salts of other metals, so that the electrodeposition method in the invention has universality for preparing the high-entropy alloy electrode, and can synthesize different quaternary, quinary, hexahydric or even seven-element high-entropy alloy electrodes. Of course, the plurality of metal sources may also include three of the above-described metal salts to synthesize a ternary alloy electrode material.
In the embodiment, the concentration of the hydrogen ions in the mixed solution prepared in step S10 is 0.01-2 mol/L, so that in the subsequent electrodeposition process, the hydrogen ions can be reduced on the surface of the cathode to form a large number of hydrogen bubbles and occupy a certain space on the surface of the cathode, so that the obtained high-entropy alloy presents a porous structure. The hydrogen ion concentration of the mixed solution may include other concentrations, for example, more than 2mol/L, as long as hydrogen bubbles can be reduced and formed during electrodeposition.
Step S20: the conductive substrate is pretreated to remove contaminants from the surface of the conductive substrate. Wherein, the step of pretreatment is to use dilute hydrochloric acid, deionized water and absolute ethyl alcohol to carry out ultrasonic cleaning on the conductive matrix in sequence, and the cleaning time is at least 15 minutes.
The order of step S10 and step S20 is not fixed. The conductive substrate is pretreated to remove contaminants on the surface thereof, but in other embodiments, other treatment methods capable of removing contaminants may be used. Of course, in the case where cleanliness of the conductive substrate is not required or the conductive substrate itself is free from contaminants, the conductive substrate may not be subjected to pretreatment, and in this case, step S20 may not be performed.
Step S30: and (4) taking the mixed solution obtained in the step (S10) as an electrolyte, taking the conductive substrate as a cathode, and carrying out electrodeposition under a negative potential, wherein the negative potential is lower than the reduction potential of hydrogen ions, and when a plurality of metal ions are reduced and deposited on the conductive substrate, the hydrogen ions are synchronously reduced on the surface of the conductive substrate to form hydrogen bubbles so as to obtain the high-entropy alloy electrode with a porous structure.
In this example, a carbon paper, a copper mesh, or a nickel foam substrate was used as a conductive substrate of the cathode, a graphite electrode was used as a counter electrode, and the mixed solution obtained in step S10 was used as an electrolyte to perform dc electrodeposition. Of course, in other embodiments, other conductive substrates may be used as the cathode, such as carbon cloth; other electrodes, such as platinum electrodes, may also be used as counter electrodes.
In order to reduce all metal ions and hydrogen ions in the electrolyte, in this example, a deposition electrode was usedThe flow density is 0.8-10A/cm 2 And electrodeposition is carried out using a sufficiently large negative potential. Since hydrogen ions are generally more difficult to reduce than metal ions, the negative potential is lower than the potential capable of reducing the hydrogen ions, so that the negative potential is large enough to drive all the metal ions to be indiscriminately and rapidly deposited on the surface of the cathode conductive substrate, and meanwhile, the hydrogen ions are reduced on the surface of the cathode conductive substrate to form hydrogen bubbles, so that the high-entropy alloy electrode material with a porous structure is formed. In other embodiments, the electrodeposition process may be optimized, for example, the deposition current density may be at 1A/cm 2 Above, the reduction and deposition of hydrogen ions and metal ions are made easier.
In the present embodiment, the deposition time of the electrodeposition is 10 to 600 seconds. In other embodiments, the deposition time of the electrodeposition may be adjusted, for example, over 600 seconds, depending on the size of the cathode conductive matrix or the quality requirements of the resulting electrode material.
By adopting the preparation method of the high-entropy alloy porous electrode provided by the embodiment of the invention, the high-entropy alloy porous electrode material can be directly synthesized by an electrodeposition method, a porous structure is formed without removing certain alloy, the structure of the material is not damaged, the method is simple, convenient and efficient, and has universality, the required equipment is simple, the requirement on operating conditions is not high, and the preparation method is beneficial to large-scale production. In the preparation process, electrodeposition is carried out under a large enough reduction potential, so that a sufficient driving force is provided for reduction of a plurality of metal ions and hydrogen ions in the electrolyte, the metal ions and the hydrogen ions are reduced on the cathode almost at the same time, wherein the metal ions are deposited on a conductive substrate of the cathode, and the hydrogen ions are reduced on the surface of the conductive substrate to form hydrogen bubbles, so that the high-entropy alloy porous electrode with uniformly distributed elements is obtained. The porous structure is beneficial to the permeation of electrolyte and the diffusion of ions and the like in the electrocatalysis reaction, and is beneficial to the improvement of the electrocatalysis performance. Meanwhile, the porous high-entropy alloy is directly deposited on the conductive substrate to form the self-supporting electrode, wherein the porous high-entropy alloy is used as an active substance of electrocatalytic reaction and is directly contacted with the conductive substrate.
The embodiment can provide the high-entropy alloy porous electrode prepared based on the preparation method. The electrode is a high-entropy alloy self-supporting electrode with a porous structure, and consists of a conductive substrate and a porous high-entropy alloy deposited on the conductive substrate, wherein the porous structure enables the electrode to have a larger specific surface area, and can be used as an electrocatalyst material to be applied to water electrolysis hydrogen production reaction. In the embodiment, the electrode material is a single-phase high-entropy alloy structure, and a plurality of elements are uniformly distributed in the material.
The embodiment also provides application of the high-entropy alloy porous electrode prepared by the preparation method. And (2) performing water electrolysis hydrogen production reaction by using a direct current electrolytic cell and the high-entropy alloy porous electrode as a working electrode and 0.1-1 mol/L potassium hydroxide solution as an electrolyte at a scanning speed of less than 10 mV/s.
The hydrogen production reaction by water electrolysis can also be carried out in an alkaline, acidic or neutral solution, and therefore, the electrolyte used for the hydrogen production reaction by water electrolysis is not limited to the potassium hydroxide solution, and an acidic solution, a neutral solution or other alkaline solutions, such as a sulfuric acid solution, a neutral phosphate buffer solution or a sodium hydroxide solution, can also be used. Of course, the concentration of the potassium hydroxide solution may be other than 0.1 to 1 mol/L. The high-entropy alloy porous electrode can show different catalytic performances of hydrogen production by electrolyzing water in different solutions.
The present invention will be described in further detail with reference to specific examples.
Example 1
The preparation process of the high-entropy alloy porous electrode comprises the following steps:
step S10: preparing a mixed solution containing a plurality of metal ions and hydrogen ions: weighing 0.597g of ferrous chloride tetrahydrate, 0.714g of cobalt chloride hexahydrate, 3.566g of nickel chloride hexahydrate, 1.199g of chromium trichloride hexahydrate and 0.359g of copper chloride dihydrate, adding into 150mL of deionized water, and stirring at a constant speed until the five metal sources are fully dissolved to form an aqueous solution of metal ions; 0.1mol of concentrated hydrochloric acid is added into the solution, and the mixture is evenly stirred for 20min to form a mixed solution.
Step S20; pretreating the conductive substrate: and (3) carrying out ultrasonic cleaning on the hydrophilic carbon paper for 15 minutes by sequentially using 3mol/L dilute hydrochloric acid, deionized water and absolute ethyl alcohol.
Step S30: performing direct current electrodeposition by using the mixed solution obtained in the step S10 as an electrolyte, the hydrophilic carbon paper pretreated in the step S20 as a cathode and a graphite rod as an anode by using an electrochemical workstation, wherein the deposition current density is 1.5A/cm 2 And the deposition time is 20 seconds, and the FeCoNiCrCu five-element high-entropy alloy porous electrode is prepared.
It should be noted that, during the electrodeposition process, hydrogen bubbles formed by reducing hydrogen ions on the cathode surface at the beginning are uniform in size, about 10 microns in size, and as the deposition time is prolonged, the bubbles gradually aggregate and increase to about 30 microns, and at this time, the bubbles leave the cathode surface. The generated hydrogen bubbles occupy a certain space on the surface of the cathode, so that the prepared high-entropy alloy electrode material presents a porous structure, and the pore size is 10-30 microns.
An electron micrograph of the high-entropy alloy porous electrode prepared by the preparation method is shown in fig. 3. FIG. 3(a) shows that the electrode material is in a porous structure, and the pore size is 10-30 microns. As shown in FIG. 3(b), the prepared high-entropy alloy porous electrode material is dendritic and assembled by particles with the size of about 100nm, and the structure is favorable for expanding the specific surface area of the material. As shown in FIG. 3(c), the prepared high-entropy alloy porous electrode material is of a single-phase face-centered cubic structure. As shown in the element content diagram in fig. 4, the atomic ratios of Cr, Fe, Co, Ni, and Cu in the electrode material are 14.33, 22.42, 17.77, 17.61, and 27.87 at.%, respectively, and the atomic ratios of the components considered in the conventional high-entropy alloy are between 5 and 35 at.%. Therefore, the quinary high-entropy alloy self-supporting electrode with the porous structure is prepared by the preparation method.
The high-entropy alloy porous electrode is used as an electrocatalyst to be applied to hydrogen production reaction by water electrolysis. The application steps are as follows:
8.417g of potassium hydroxide is weighed and added into 150ml of deionized water, and the mixture is stirred until the potassium hydroxide is completely dissolved, so that 1mol/L potassium hydroxide electrolyte solution is formed;
Continuously introducing high-purity nitrogen into the electrolyte solution for 20min to remove oxygen in the electrolyte solution and form a nitrogen-saturated electrolyte solution;
and (3) performing hydrogen production reaction by electrolyzing water by using a direct current electrolytic cell and taking the FeCoNiCrCu five-element high-entropy alloy porous electrode as a working electrode. The polarization curve and Tafel curve of the hydrogen production reaction by electrolyzing water were obtained at a scanning speed of 5mV/s, and as shown in FIGS. 5 and 6, the current density was 10mA/cm 2 The overpotential is 94mV, and the Tafel slope is 68mV/dec, which shows that the quinary high-entropy alloy porous electrode has ultrahigh electrocatalytic hydrogen production performance and can be comparable with commercial noble metal catalysts.
Example 2
The preparation process of the high-entropy alloy porous electrode comprises the following steps:
step S10: preparing a mixed solution containing a plurality of metal ions and hydrogen ions: weighing 0.597g of ferrous chloride tetrahydrate, 0.714g of cobalt chloride hexahydrate, 3.566g of nickel chloride hexahydrate, 1.199g of chromium trichloride hexahydrate, 0.359g of copper chloride dihydrate and 0.205g of zinc chloride, adding the materials into 150mL of deionized water, and stirring at a constant speed until the six metal sources are fully dissolved to form an aqueous solution of metal ions; adding 0.1mol of concentrated hydrochloric acid into the solution, and uniformly stirring for 20min to form a mixed solution;
Step S20: pretreating the conductive substrate: sequentially using 3mol/L dilute hydrochloric acid, deionized water and absolute ethyl alcohol to ultrasonically clean the hydrophilic carbon paper for 15 minutes;
step S30: utilizing an electrochemical workstation, taking the mixed solution obtained in the step S10 as an electrolyte, taking hydrophilic carbon paper as a cathode and taking a graphite rod as an anode, and carrying out electrodeposition with the deposition current density of 1.5A/cm 2 And the deposition time is 20 seconds, and the FeCoNiCrCuZn six-element high-entropy alloy porous electrode is prepared.
An electron microscope photograph of the high-entropy alloy porous electrode prepared by the preparation method is shown in fig. 7, and the electrode material has a porous structure, is dendritic and is a single-phase high-entropy alloy structure. As shown in fig. 8, the atomic ratios of Cr, Fe, Co, Ni, Cu, and Zn in the material were 11.85, 14.18, 12.42, 15.11, 31.01, and 15.43 at.%, respectively, and the contents of the six elements were not greatly different. Therefore, the six-element high-entropy alloy self-supporting electrode with the porous structure is successfully prepared by the preparation method.
The high-entropy alloy porous electrode is used as an electrocatalyst to be applied to hydrogen production reaction by water electrolysis. The difference from the example 1 is that the FeCoNiCrCuZn six-element high-entropy alloy porous electrode obtained in the example 2 is used as a working electrode, and a polarization curve and a Tafel curve of the hydrogen production reaction by electrolyzing water are obtained, as shown in fig. 9 and fig. 10, and the current density is 10mA/cm 2 When the electrode is used, the overpotential is 135mV, and the Tafel slope is 94mV/dec, which shows that the six-membered high-entropy alloy porous electrode has excellent electrocatalytic hydrogen production performance. In addition, other application steps of embodiment 2 are basically the same as those of embodiment 1, and are not described again here.
Example 3
The preparation process of the electrode material comprises the following steps:
step S10: preparing a mixed solution containing a plurality of metal ions and hydrogen ions: weighing 0.597g of ferrous chloride tetrahydrate, 0.714g of cobalt chloride hexahydrate, 3.566g of nickel chloride hexahydrate, 1.199g of chromium trichloride hexahydrate, 0.359g of copper chloride dihydrate, 0.205g of zinc chloride and 5.938g of manganese chloride tetrahydrate, adding into 150mL of deionized water, and stirring at a constant speed until seven metal sources are fully dissolved to form a metal ion aqueous solution; 0.1mol of concentrated hydrochloric acid is added into the solution, and the mixture is evenly stirred for 20min to form a mixed solution.
Step S30: utilizing an electrochemical workstation, taking the mixed solution obtained in the step S10 as an electrolyte, taking hydrophilic carbon paper as a cathode, taking a graphite rod as an anode, and carrying out electrodeposition with the deposition current density of 2A/cm 2 And the deposition time is 15 seconds, and the FeCoNiCrCuMnZn seven-element high-entropy alloy porous electrode is prepared.
An electron microscope photograph of the high-entropy alloy porous electrode prepared by the preparation method is shown in fig. 11, and the electrode material has a porous structure, is dendritic and is of a single-phase structure. And as can be seen from the element content diagram of the electrode material in fig. 12, the contents of seven elements in the material are not very different. Therefore, the seven-element high-entropy alloy self-supporting electrode with the porous structure is successfully prepared by the preparation method.
The high-entropy alloy porous electrode is used as an electrocatalyst to be applied to hydrogen production reaction by water electrolysis. The difference from example 1 is that the FeCoNiCrCuMnZn seven-element high entropy alloy porous electrode obtained in example 3 is used as a working electrode, and the polarization curve and Tafel curve of the hydrogen production reaction by electrolyzing water are shown in FIG. 13 and FIG. 14, and the current density is 10mA/cm 2 When the electrode is used, the overpotential is 118mV, and the Tafel slope is 74mV/dec, which shows that the seven-element high-entropy alloy porous electrode has excellent electrocatalytic hydrogen production performance. In addition, other application steps of embodiment 3 are basically the same as those of embodiment 1, and are not described again here.
Example 4
The difference from example 1 is that, in step S10, 0.1g of platinum tetrachloride was added during the preparation of the mixed solution, and the mixture was stirred at a constant speed until the six metal sources were sufficiently dissolved to form an aqueous solution containing six metal ions. The electrode obtained by final electrodeposition is a FeCoNiCrCuPt six-membered high-entropy alloy porous electrode containing noble metal. In addition, other preparation steps of example 4 are basically the same as those of example 1, and are not repeated herein.
Example 5
The difference from example 1 is that in step S30, the deposition current density of electrodeposition was 0.8A/cm 2 . In addition, other preparation steps of the embodiment 5 are basically the same as those of the embodiment 1, and are not repeated herein.
Example 6
The difference from example 1 is that in step S30, the deposition current density of electrodeposition was 10A/cm 2 The deposition time was 10 seconds. In addition, the other preparation steps of example 6 are substantially the same as those of example 1, and are not repeated hereThe description is given.
It should also be noted that, in the case of the embodiments of the present invention, features of the embodiments and examples may be combined with each other to obtain a new embodiment without conflict.
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and the scope of the present invention is subject to the scope of the claims.

Claims (1)

1. A preparation method of a high-entropy alloy porous electrode is characterized by comprising the following steps:
step S10: preparing a mixed solution containing various metal ions and hydrogen ions, weighing 0.597g of ferrous chloride tetrahydrate, 0.714g of cobalt chloride hexahydrate, 3.566g of nickel chloride hexahydrate, 1.199g of chromium trichloride hexahydrate and 0.359g of copper chloride dihydrate, adding the mixture into 150mL of deionized water, and stirring at a constant speed until the mixture is fully dissolved to form a metal ion aqueous solution; adding 0.1mol of concentrated hydrochloric acid into the solution, and uniformly stirring for 20min to form a mixed solution;
Step S20: pretreating a conductive substrate, wherein the conductive substrate is hydrophilic carbon paper, and ultrasonically cleaning the hydrophilic carbon paper for 15 minutes by sequentially using 3mol/L hydrochloric acid, deionized water and absolute ethyl alcohol;
step S30: performing direct current deposition at a negative potential by using an electrochemical workstation and a graphite rod as an anode, the mixed solution obtained in the step S10 as an electrolyte and the hydrophilic carbon paper pretreated in the step S20 as a cathode, wherein the deposition current density is 1.5A/cm 2 The deposition time is 20 seconds; the negative potential is lower than the reduction potential of the hydrogen ions, the multiple metal ions and the hydrogen ions are indiscriminately and simultaneously reduced at the cathode, and when the multiple metal ions are indiscriminately and uniformly deposited on the conductive substrate, the hydrogen ions are synchronously reduced on the surface of the conductive substrate to form hydrogen bubbles, so that the FeCoNiCrCu quinary high-entropy alloy self-supporting electrode with a porous structure is prepared;
hydrogen bubbles formed by reducing hydrogen ions on the surface of a cathode at the beginning of electrodeposition are uniform in size and 10 microns in size, the bubbles gradually gather and increase to 30 microns and leave the surface of the cathode along with the extension of the deposition time, and the generated hydrogen bubbles occupy a certain space on the surface of the cathode, so that the prepared high-entropy alloy electrode material presents a porous structure, and the pore size is 10-30 microns;
The prepared high-entropy alloy porous electrode material is dendritic and is assembled by particles with the size of 100 nm; the FeCoNiCrCu quinary high-entropy alloy electrode consists of the conductive substrate and a high-entropy alloy porous electrode material which is indiscriminately and uniformly deposited on the conductive substrate, the high-entropy alloy porous electrode material is of a single-phase face-centered cubic structure, and the atomic proportions of Cr, Fe, Co, Ni and Cu in the electrode material are 14.33, 22.42, 17.77, 17.61 and 27.87 at.%, respectively.
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