Porous structure high-entropy alloy oxygen evolution catalyst and preparation method thereof
The porous high-entropy alloy catalyst composed of six elements, Al, Co, Fe, Ni, Mo and V, solves the problems of expensive precious metals and limited active sites of transition metals in existing OER catalysts, and achieves highly efficient water electrolysis catalytic performance, making it suitable for large-scale applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YANCHENG INST OF TECH
- Filing Date
- 2026-04-15
- Publication Date
- 2026-06-12
AI Technical Summary
Existing OER catalysts suffer from the high cost and poor stability of precious metals, and the limited active sites and poor conductivity of transition metal catalysts, resulting in low water electrolysis efficiency and making large-scale application difficult.
A porous high-entropy alloy catalyst composed of six elements, Al, Co, Fe, Ni, Mo and V, is formed into a three-dimensional porous structure through high-energy ball milling and dealloying treatment, which increases the active sites and specific surface area and optimizes the electronic structure to improve catalytic performance.
It significantly reduces overpotential, improves the mass transfer efficiency and catalytic activity of water electrolysis, is suitable for large-scale industrial applications, and has a simple and low-cost process.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of water electrolysis catalyst technology, and in particular to a porous high-entropy alloy oxygen evolution reaction catalyst and its preparation method. Background Technology
[0002] With the urgent global pursuit of sustainable energy and carbon neutrality, hydrogen energy, as a clean and efficient secondary energy source, has attracted much attention for its development and utilization. Among numerous hydrogen production technologies, water electrolysis is considered the most promising green hydrogen production route due to its advantages such as zero carbon emissions and high product purity. The water electrolysis process includes the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. The OER is a complex process involving four electron transfers, characterized by slow kinetics and high overpotential, becoming a bottleneck restricting the overall efficiency of water electrolysis. Therefore, developing efficient and stable OER catalysts is crucial to lowering the reaction energy barrier and improving energy conversion efficiency.
[0003] Noble metal-based catalysts such as IrO2 and RuO2 can significantly reduce the overpotential of the oxygen evolution reaction (OER). However, their high cost and poor long-term stability severely limit their prospects for large-scale industrial applications. Transition metal (such as Co, Ni, and Fe) oxides, hydroxides, phosphides, and sulfides are gradually gaining attention. For example, patent CN117643891 A discloses a boron-doped metal oxide / hydroxide OER catalyst and its preparation method, which prepares a catalyst composed of two phases: a bimetallic oxide and a layered bimetallic hydroxide, through co-precipitation and hydrothermal reaction. The overpotential at room temperature is 230-270 mV, and at 100 mA / cm²... 2 It exhibits good stability after operating at a current density of 10 mA / cm² for 300 h. Patent CN120060915 A discloses an oxygen evolution reaction electrocatalyst, its preparation method, and its application. A bimetallic phosphide composite carbon nanotube catalyst was prepared by chemical vapor deposition and electrodeposition. In a potassium hydroxide electrolyte solution, it exhibits good stability at a current density of 10 mA / cm². 2 At the given current density, the overpotential is 320 mV, the Tafel slope is 84.04 mV / dec, and the current density decays by 23%. Although transition metal-based catalysts are widely available and inexpensive, their intrinsic conductivity is poor and their active sites are limited, resulting in a significant gap in catalytic activity compared to noble metal catalysts.
[0004] High-entropy alloys composed of multiple principal metals have broad application prospects in the field of electrocatalytic water splitting due to their adjustable composition, electronic structure, and good durability in corrosive electrolytes. For example, patent CN 119897125 A discloses a high-entropy alloy oxide catalyst and its preparation method and application, which selects three metal elements and mixes them with Ru and Co elements, and obtains the high-entropy alloy oxide catalyst through casting, ball milling, and calcination processes. Patent CN 115449693 A discloses a preparation method and application of a framework-structured high-entropy alloy oxygen evolution catalyst, which uses Fe, Co, Ni, Cu, Mg, Mn metal salts and nickel foam to prepare a metal salt framework structure, and then reduces it with sodium borohydride to obtain a framework-structured high-entropy alloy catalyst. How to simultaneously improve intrinsic activity and specific surface area through reasonable element selection and ingenious structural design is the current challenge facing the research and development of high-entropy alloy catalysts. Summary of the Invention
[0005] To address the problems existing in current catalyst systems and preparation techniques, this invention provides a porous high-entropy alloy oxygen evolution catalyst and its preparation method. The porous structure of this invention provides abundant catalytic active sites, and the catalyst exhibits excellent oxygen evolution reaction performance in potassium hydroxide.
[0006] One object of the present invention is to provide a multi-element synergistic hexa-element high-entropy alloy oxygen evolution catalyst with a porous structure.
[0007] This invention selects six elements—Al, Co, Fe, Ni, Mo, and V—to construct a high-entropy alloy system. The atomic percentages of Co, Fe, Mo, Ni, and V are 1:1:1:1:1. Co, Fe, and Ni are recognized as active elements for OER (Organic Ergonomic Reduction). The introduction of Mo and V can further regulate the electronic structure of the alloy, while Al not only greatly promotes the formation of the hexa-element high-entropy alloy solid solution but is also cleverly designed as a "sacrificial template" for subsequent construction of porous structures. In some preferred embodiments, the mass percentage of Al is 30-40%.
[0008] Another object of the present invention is to provide a method for preparing the above-mentioned high-entropy alloy oxygen evolution catalyst.
[0009] In some embodiments, the preparation method includes the following steps:
[0010] (1) Mix the raw materials cobalt powder, iron powder, molybdenum powder, nickel powder and vanadium powder evenly, and then perform high-energy ball milling to obtain pentagonal high-entropy alloy powder;
[0011] (2) Add aluminum powder of different contents to the pentagonal high-entropy alloy powder and perform secondary ball milling to obtain hexaagonal high-entropy alloy powder;
[0012] (3) The hexa-element high-entropy alloy powder is laid on the pretreated nickel foam and pressed into tablets using a powder tablet press.
[0013] (4) The above electrodes are subjected to dealloying treatment to obtain a porous high-entropy alloy catalyst.
[0014] In step (1), the metal powders are mixed in equal atomic ratios.
[0015] In step (1), the high-energy ball milling process parameters are: a ball-to-material ratio of 20:1-40:1, a diameter of zirconia ceramic balls of 2-12 mm, a rotation speed of 300-450 rpm, and a milling time of 10-54 h. In some more preferred embodiments, the milling speed is 450 rpm and the milling time is 54 h.
[0016] In step (2), the mass percentage of Al added is 30-40%.
[0017] In step (2), the process parameters for the secondary ball milling are: ball-to-material ratio of 15:1, ball milling speed of 300-450 rpm, and ball milling time of 4-16 h.
[0018] In step (3), the pretreatment process for the nickel foam is as follows: ultrasonic cleaning in acetone and deionized water for 5-10 min each; ultrasonic cleaning in 1-2 M hydrochloric acid solution for 20-40 min; then rinsing repeatedly with deionized water and anhydrous ethanol, and then air-drying naturally.
[0019] In step (3), the pressure of the electrode prepared by the powder press is 10-20 MPa.
[0020] In step (4), the dealloying process is as follows: the electrode is dealloyed using a 0.5-2 M sodium hydroxide solution at room temperature.
[0021] In step (4), the hexa-element high-entropy alloy after dealloying has a single body-centered cubic structure.
[0022] In step (4), a three-dimensional porous structure is formed in situ inside the electrode material after dealloying.
[0023] Compared with the prior art, the present invention has the following beneficial effects:
[0024] (1) The hexa-element high-entropy alloy catalyst obtained in this invention exhibits synergistic effects of multiple elements and demonstrates excellent oxygen evolution reaction performance. The three-dimensional porous structure designed in this invention greatly increases the specific surface area of the high-entropy alloy catalyst, providing more active sites. The abundant pores facilitate the penetration of electrolyte and the rapid escape of bubbles during the reaction, significantly improving the mass transfer efficiency.
[0025] (2) This invention obtains a single-phase body-centered cubic hexa-element high-entropy alloy catalyst through a unique "two-step ball milling + dealloying" preparation method. Compared with the methods of preparing high-entropy alloy powder by melting + atomization or melting + ball milling + calcination, the process is simpler, less expensive, and easier to scale up.
[0026] (3) When the porous high-entropy alloy catalyst preferred in this invention is used for the oxygen evolution reaction of water electrolysis, it exhibits excellent water electrolysis performance. Under high current density, the higher the aluminum content, the better the OER performance of the high-entropy alloy in this system. The addition of aluminum significantly reduces the overpotential and increases the active sites. Attached Figure Description
[0027] Figure 1 These are the XRD patterns of the high-entropy alloy powders in Examples 1-3 and the comparative examples;
[0028] Figure 2 This is the XRD pattern of the high-entropy alloy powder compact after dealloying treatment in Example 2;
[0029] Figure 3 This is the SEM surface scan image of the high-entropy alloy powder compact after dealloying treatment in Example 3;
[0030] Figure 4 shows the linear sweep (LSV) curves and Tafel slope plots of the high-entropy alloy catalysts in Examples 1-3 and the comparative examples.
[0031] Figure 5 The double-layer capacitance (C) of the high-entropy alloy catalysts in Examples 1-3 and the comparative examples is... dl (Line graph) Detailed Implementation
[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is further described in detail below with reference to specific embodiments. The following embodiments are merely for illustrating the invention in detail and do not limit the scope of the invention in any way. Experimental methods not specifically described in the embodiments are generally performed under conventional conditions and as described in the manual. Unless otherwise specified, the equipment, materials, reagents, etc., used are commercially available.
[0033] Example 1
[0034] A method for preparing a porous CoFeMoNiV-30Al high-entropy alloy oxygen evolution catalyst is as follows:
[0035] Step 1: Cobalt powder, iron powder, molybdenum powder, nickel powder, and vanadium powder with a purity of 99.5% and a particle size less than 300 mesh were mixed in an equiatomic ratio and placed in a planetary ball mill for high-energy ball milling under argon protection to obtain a pentagonal high-entropy alloy powder. The ball-to-powder ratio was 20:1, and the mass ratio of zirconia ceramic balls of different diameters was Φ12 mm:Φ8 mm:Φ4 mm:Φ2 mm = 1:1:1:1. The ball milling time was 54 h, and the rotation speed was 450 rpm. After ball milling, the prepared powder was taken out and dried in a vacuum drying oven at 80℃ for 2 h.
[0036] Step 2: Add 99.5% pure aluminum powder with a particle size of 200 mesh to the pentagonal high-entropy alloy powder obtained in Step 1 for secondary ball milling to obtain hexaagonal high-entropy alloy powder. The ball-to-powder ratio is 15:1, the ball milling time is 8 hours, and the rotation speed is 450 rpm.
[0037] Step 3: The hexa-element high-entropy alloy powder is laid on the pretreated nickel foam and pressed into tablets using a powder tablet press with a pressing force of 10 MPa. The electrode size is 1×1 cm. -2 ;
[0038] Step 4: The electrode was dealloyed using a 1 M sodium hydroxide solution. After the absence of obvious bubbles, the sample was removed, repeatedly washed with deionized water and anhydrous ethanol, and then dried to obtain a porous high-entropy alloy catalytic electrode.
[0039] Example 2
[0040] A method for preparing a porous CoFeMoNiV-35Al high-entropy alloy oxygen evolution catalyst is as follows:
[0041] Step 1: Cobalt powder, iron powder, molybdenum powder, nickel powder, and vanadium powder with a purity of 99.5% and a particle size less than 300 mesh were mixed in an equiatomic ratio and placed in a planetary ball mill for high-energy ball milling under argon protection to obtain a pentagonal high-entropy alloy powder. The ball-to-powder ratio was 20:1, and the mass ratio of zirconia ceramic balls of different diameters was Φ12 mm:Φ8 mm:Φ4 mm:Φ2 mm = 1:1:1:1. The ball milling time was 54 h, and the rotation speed was 450 rpm. After ball milling, the prepared powder was taken out and dried in a vacuum drying oven at 80℃ for 2 h.
[0042] Step 2: Add 99.5% pure aluminum powder with a particle size of 200 mesh to the pentagonal high-entropy alloy powder obtained in Step 1 for secondary ball milling to obtain hexaagonal high-entropy alloy powder. The ball-to-powder ratio is 15:1, the ball milling time is 12 hours, and the rotation speed is 450 rpm.
[0043] Step 3: The above-mentioned hexa-element high-entropy alloy powder is spread on the pretreated nickel foam and pressed into tablets using a powder tablet press with a pressing force of 10 MPa and an electrode size of 1×1 cm.-2 ;
[0044] Step 4: The electrode was dealloyed using a 1 M sodium hydroxide solution. After the absence of obvious bubbles, the sample was removed, repeatedly washed with deionized water and anhydrous ethanol, and then dried to obtain a porous high-entropy alloy catalytic electrode.
[0045] Example 3
[0046] A method for preparing a porous CoFeMoNiV-40Al high-entropy alloy oxygen evolution catalyst is as follows:
[0047] Step 1: Cobalt powder, iron powder, molybdenum powder, nickel powder, and vanadium powder with a purity of 99.5% and a particle size less than 300 mesh were mixed in an equiatomic ratio and placed in a planetary ball mill for high-energy ball milling under argon protection to obtain a pentagonal high-entropy alloy powder. The ball-to-powder ratio was 20:1, and the mass ratio of zirconia ceramic balls of different diameters was Φ12 mm:Φ8 mm:Φ4 mm:Φ2 mm = 1:1:1:1. The ball milling time was 54 h, and the rotation speed was 450 rpm. After ball milling, the prepared powder was taken out and dried in a vacuum drying oven at 80℃ for 2 h.
[0048] Step 2: Add 99.5% pure aluminum powder with a particle size of 200 mesh to the pentagonal high-entropy alloy powder obtained in Step 1 for secondary ball milling to obtain hexaagonal high-entropy alloy powder. The ball-to-powder ratio is 15:1, the ball milling time is 8 hours, and the rotation speed is 450 rpm.
[0049] Step 3: The above-mentioned hexa-element high-entropy alloy powder is spread on the pretreated nickel foam and pressed into tablets using a powder tablet press with a pressing force of 10 MPa and an electrode size of 1×1 cm. -2 ;
[0050] Step 4: The electrode was dealloyed using a 1 M sodium hydroxide solution. After the absence of obvious bubbles, the sample was removed, repeatedly washed with deionized water and anhydrous ethanol, and then dried to obtain a porous high-entropy alloy catalytic electrode.
[0051] Comparative Example
[0052] The preparation method of CoFeMoNiV pentagonal high-entropy alloy oxygen evolution catalyst is as follows:
[0053] Step 1: Cobalt powder, iron powder, molybdenum powder, nickel powder, and vanadium powder with a purity of 99.5% and a particle size less than 300 mesh were mixed in an equiatomic ratio and placed in a planetary ball mill for high-energy ball milling under argon protection to obtain a pentagonal high-entropy alloy powder. The ball-to-powder ratio was 20:1, and the mass ratio of zirconia ceramic balls of different diameters was Φ12 mm:Φ8 mm:Φ4 mm:Φ2 mm = 1:1:1:1. The ball milling time was 54 h, and the rotation speed was 450 rpm. After ball milling, the prepared powder was taken out and dried in a vacuum drying oven at 80℃ for 2 h.
[0054] Step 2: The above-mentioned pentagonal high-entropy alloy powder is laid on the pretreated nickel foam and pressed into tablets using a powder tablet press with a pressing force of 10 MPa and an electrode size of 1×1 cm. -2 ;
[0055] Step 3: The electrode was dealloyed using a 1 M sodium hydroxide solution. After the absence of obvious bubbles, the sample was removed, repeatedly washed with deionized water and anhydrous ethanol, and then dried to obtain a porous high-entropy alloy catalytic electrode.
[0056] The high-entropy alloys produced by high-energy ball milling and dealloying were characterized structurally and tested for catalytic performance.
[0057] Experimental Example 1: Phase Analysis of High-Entropy Alloy Powder After High-Energy Ball Milling
[0058] Figure 1 The XRD patterns of CoFeMoNiV-xAl (x=0, 30, 35, 40 wt%) high-entropy alloy powders after high-energy ball milling in Examples 1-3 and the comparative example are shown. The study indicates that during ball milling, low-melting-point elements gradually dissolve into the high-melting-point Mo element. After ball milling for 54 h (comparative example), only the Mo solid solution phase and the five-element high-entropy alloy phase were observed in the pentagonal system. After secondary ball milling with different contents of Al (Examples 1-3), Al significantly promoted the formation of a single-phase BCC structure hexa-element high-entropy alloy. Small amounts of Al, Mo, and Al2O3 also existed in the alloy system. 86 Fe 14 AlNi3 substances.
[0059] Experimental Example 2: Phase Analysis of High-Entropy Alloy Powder Briques After Dealloying
[0060] Figure 2 The figure shows the XRD pattern of the CoFeMoNiV-40Al high-entropy alloy powder after dealloying treatment in Example 3. As can be seen from the figure, the phase of the hexa-element high-entropy alloy after dealloying is a single-phase BCC solid solution. The Al components in the elemental Al and AlNi3 phases were selectively etched away in 1 M sodium hydroxide solution. In addition, a small amount of Al remains. 86 Fe 14 Phase residue.
[0061] Experimental Example 3 SEM-EDS Analysis of the High-Entropy Alloy Powder Compacts after Dealloying
[0062] Figure 3 The SEM surface scan pattern of the CoFeMoNiV-40Al high-entropy alloy powder compact after dealloying treatment in Example 3 is shown. It can be seen from the EDS element distribution map that the composition of the six-element high-entropy alloy is evenly distributed without obvious segregation. Except for inevitable surface oxidation, the six-element high-entropy alloy mainly exists in the metallic state.
[0063] Experimental Example 4 Oxygen Evolution Reaction Performance of High-Entropy Alloys
[0064] The electrochemical tests were carried out in a three-electrode system. The working electrode was the prepared high-entropy alloy electrode, the counter electrode was a carbon rod, the reference electrode was a Hg / HgO electrode, and the electrolyte was 1 M KOH solution saturated with O2. All potentials were converted to the potential relative to the reversible hydrogen electrode, and no iR compensation was performed.
[0065] Figure 4a The LSV curves of CoFeMoNiV-xAl (x = 0, 30, 35, 40 wt%) high-entropy alloys are shown. It can be seen that the six-element high-entropy alloys with Al addition (Examples 1 - 3) all exhibit better OER performance than the five-element alloy without Al addition (comparative example). At a current density of 100 mA·cm -2 , the overpotential relationship of each catalyst is CoFeMoNiV-40Al < CoFeMoNiV-35Al < CoFeMoNiV-30Al < CoFeMoNiV. The CoFeMoNiV-40Al high-entropy alloy catalyst in Example 3 exhibits the best OER performance, indicating that the addition of aluminum element significantly improves the OER performance of the alloys in this system.
[0066] From Figure 4b the Tafel slope of the high-entropy alloys, it can be seen that with the increase of aluminum content, the Tafel slope of the high-entropy alloy catalyst decreases. The CoFeMoNiV-40Al high-entropy alloy in Example 3 has the lowest Tafel slope of 92.3 mV / dec, further proving its optimal OER catalytic performance.
[0067] To analyze the intrinsic activity of the high-entropy alloys, the double-layer capacitance C dl measured by cyclic voltammetry was used to evaluate the electrochemically active surface area of the electrode. It can be seen from Figure 5 that the C dlThe values were 10.31, 9.45, 8.47, and 5.08 mF / cm, respectively. 2 Among them, CoFeMoNiV-40Al has the largest surface area, indicating that the porous CoFeMoNiV-40Al electrode has the largest electrochemical active surface area, which is twice that of CoFeMoNiV. Figure 5 The results show that with the increase of aluminum content, the number of active sites in the hexa-porous high-entropy alloy catalyst increases, which is consistent with its electrocatalytic oxygen evolution performance.
[0068] The above embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.
Claims
1. A porous high-entropy alloy oxygen evolution catalyst, characterized in that, The high-entropy alloy catalyst is composed of Al, Co, Fe, Mo, Ni, and V; the atomic percentages of Co, Fe, Mo, Ni, and V are 1:1:1:1:1, and the mass percentage of Al is 30-40%.
2. The preparation method of the porous high-entropy alloy oxygen evolution catalyst according to claim 1, characterized in that, Includes the following steps: (1) Prepare five-element high-entropy alloy powder by mixing cobalt powder, iron powder, molybdenum powder, nickel powder and vanadium powder in equal atomic ratio and ball milling for different times. (2) Add aluminum powder of different contents and perform secondary ball milling to obtain hexa-element high-entropy alloy powder; (3) The hexa-element high-entropy alloy powder is laid on the pretreated nickel foam and pressed into tablets using a powder tablet press. (4) The electrodes were dealloyed with sodium hydroxide solution to prepare a porous high-entropy alloy catalyst.
3. The method for preparing the porous high-entropy alloy catalyst according to claim 2, characterized in that, In step (1), the process parameters of the high-energy ball mill are: ball-to-material ratio of 20:1-40:1, diameter of zirconia ceramic balls of 2-12 mm, rotation speed of 300-450 rpm, and ball milling time of 10-54 h.
4. The method for preparing the porous high-entropy alloy catalyst according to claim 2, characterized in that, In step (2), the process parameters for the secondary ball milling are: ball-to-material ratio of 15:1, ball milling speed of 300-450 rpm, and ball milling time of 4-16 h.
5. The method for preparing the porous high-entropy alloy catalyst according to claim 2, characterized in that, In step (2), the hexa-element high-entropy alloy is a single-phase solid solution with a BCC structure.
6. The method for preparing the porous high-entropy alloy catalyst according to claim 2, characterized in that, In step (3), the pretreatment process of the nickel foam is as follows: ultrasonic cleaning in acetone and deionized water for 5-10 min each; ultrasonic cleaning in 1-2 M hydrochloric acid solution for 20-40 min; then rinsing repeatedly with deionized water and anhydrous ethanol several times, and then air-drying naturally.
7. The method for preparing the porous high-entropy alloy catalyst according to claim 2, characterized in that, In step (3), the pressure for preparing the electrode using a powder press is 10-20 MPa.
8. The method for preparing the porous high-entropy alloy catalyst according to claim 2, characterized in that, In step (4), the dealloying process is as follows: the electrode is dealloyed using a 0.5-2 M sodium hydroxide solution at room temperature.
9. The method for preparing the porous high-entropy alloy catalyst according to claim 2, characterized in that, In step (4), after the dealloying treatment, a single BCC phase high-entropy alloy oxygen evolution catalyst with a three-dimensional porous structure is obtained.