A low-Pt high-entropy alloy water electrolysis catalyst and its preparation method and application

Abstract

The present invention belongs to the technical field of electrolytic water catalysts and relates to a low-Pt high-entropy alloy electrolytic water catalyst, a preparation method, and an application thereof. Five metal elements, namely, Mn, Ni, Cu, Pt, and any one of La, Mo, Co, V, and Ti, are selected and combined to prepare an efficient and stable high-entropy alloy catalyst. No pH adjustment is required during the process, and the process is simple, easy to operate, and the preparation cost is low, thus enabling industrial production. The MnNiCuPt (La, Mo, Co, V, Ti) high-entropy alloy catalyst prepared by the present invention exhibits excellent electrolytic water performance, thereby reducing the catalyst cost and improving the catalytic performance.

Description

Technical Field

[0001] The present invention relates to the technical field of water electrolysis catalysts, and in particular to a low-Pt high-entropy alloy water electrolysis catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] The global challenges of energy depletion and severe pollution have led to increasing attention for hydrogen, a green energy source. The key to the development of a hydrogen economy lies in its production. Currently, there are many methods for producing hydrogen, the most important of which is obtaining large quantities of high-purity hydrogen through water electrolysis. Water electrolysis has become a promising method for hydrogen production due to its simplicity, low cost, zero greenhouse gas emissions, and high energy conversion efficiency. Water electrolysis primarily involves two reactions: oxygen production and hydrogen production. However, hydrogen produced by water electrolysis currently accounts for only approximately 4% of global production. This is due to the high overpotentials of the hydrogen evolution reaction (RE) and the oxygen evolution reaction (OER) in the electrode reactions involved in water electrolysis. The conversion efficiency of many electrocatalysts remains relatively low, requiring significant amounts of electrical energy. This increases the cost of water electrolysis and limits its large-scale application.

[0003] Among numerous catalysts, precious metal electrocatalysts are currently the most active catalysts for water electrolysis. Electrocatalysts are crucial for the entire hydrogen production reaction in water electrolysis. Ideal electrocatalysts should possess corrosion resistance, good specific surface area, porosity, catalytic activity, electrical conductivity, electrochemical stability, low cost, and environmental friendliness. Cathodic hydrogen evolution electrocatalysts operating in strongly acidic or alkaline environments are prone to corrosion, agglomeration, and wear. To ensure the performance and service life of electrolyzers, hydrogen evolution catalysts are primarily made from corrosion-resistant precious metals such as platinum and palladium, and their alloys. However, the high price and relatively small reserves of precious metal catalysts significantly limit their large-scale production and application. Therefore, to achieve efficient and industrialized hydrogen production from water electrolysis, it is imperative to identify low-cost hydrogen evolution catalysts with excellent hydrogen evolution performance. Currently reported high-performance water electrolysis catalysts are mostly monometallic or bimetallic, but most still require large overpotentials to achieve the desired current density in alkaline electrolytes. Therefore, the exploration of new multifunctional water electrolysis catalysts is urgently needed. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide a low-Pt high-entropy alloy water electrolysis catalyst and its preparation method and application.

[0005] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0006] A method for preparing a low-Pt high-entropy alloy water electrolysis catalyst, wherein the low-Pt high-entropy alloy is MnNiCuPt (La, Mo, Co, V, Ti), comprising the following steps:

[0007] S1. Prepare any one of La, Mo, Co, V, Ti and Mn, Ni, Cu, Pt as metal elements according to the high entropy alloy ratio, and perform surface pretreatment on the metal elements before use;

[0008] S2. Place metal elements Mn, Ni, Cu, and Pt in one water-cooled crucible, and place any one of metal elements La, Mo, Co, V, and Ti in another water-cooled crucible, and place both water-cooled crucibles in a vacuum arc melting furnace that has been evacuated and filled with an inert protective gas.

[0009] S3. Inert gas is continuously introduced during the arc melting process, and electromagnetic stirring is also performed during the arc melting process. After cooling, a sample is obtained, and then the sample is remelted multiple times. After the last remelting, it is cooled to obtain a MnNiCuPt (La, Mo, Co, V, Ti) high entropy alloy water electrolysis catalyst.

[0010] As a preferred embodiment of the method for preparing a low-Pt high-entropy alloy water electrolysis catalyst described in the present invention, in which: in the step S1, the surface pretreatment is to remove impurities and oxides on the surface of the metal element, and then use acetone as a cleaning solvent to vibrate and clean the metal element under the action of ultrasound for 4 to 6 minutes.

[0011] As a preferred embodiment of the method for preparing a low-Pt high-entropy alloy water electrolysis catalyst according to the present invention, wherein: in step S1, the power density of the ultrasonic wave is 0.75-0.85 W / cm 2 , frequency is 30~35Hz.

[0012] As a preferred embodiment of the method for preparing a low-Pt high-entropy alloy water electrolysis catalyst according to the present invention, wherein: in step S2, the inert protective gas is introduced after vacuuming: when the vacuum reaches 2×10 -3 After reaching 5 Pa, argon protective gas was introduced.

[0013] As a preferred embodiment of the method for preparing a low-Pt high-entropy alloy water electrolysis catalyst described in the present invention, wherein: in the step S3, when the sample is remelted multiple times, the sample is turned over each time it is remelted, and is cooled after the remelting is completed to remove the surface oxide layer of the sample.

[0014] As a preferred embodiment of the method for preparing a low-Pt high-entropy alloy water electrolysis catalyst described in the present invention, wherein: in step S3, the arc melting current is 60-100A, and the arc melting time is 30 minutes.

[0015] As a preferred embodiment of the method for preparing a low-Pt high-entropy alloy water electrolysis catalyst described in the present invention, in step S3, the number of remelting is 3 to 5 times, and the time for each remelting to keep the alloy liquid in a molten state is 2 to 3 minutes.

[0016] To solve the above technical problems, according to another aspect of the present invention, the present invention provides the following technical solutions:

[0017] A low-Pt high-entropy alloy water electrolysis catalyst is prepared by the above method, wherein the low-Pt high-entropy alloy is MnNiCuPt (La, Mo, Co, V, Ti).

[0018] As a preferred embodiment of the low-Pt high-entropy alloy water electrolysis catalyst described in the present invention, the following components are present, in atomic percentage: Mn 20%, Ni 20%, Cu 20%, Pt 20%, and 20% of any one of La, Mo, Co, V, and Ti.

[0019] An application of the above-mentioned low-Pt high-entropy alloy water electrolysis catalyst in the field of water electrolysis.

[0020] The beneficial effects of the present invention are as follows:

[0021] The present invention provides a low-Pt high-entropy alloy water electrolysis catalyst, a preparation method, and an application thereof. Five metal elements, namely, Mn, Ni, Cu, Pt, and any one of La, Mo, Co, V, and Ti, are selected and combined to prepare an efficient and stable high-entropy alloy catalyst. No pH adjustment is required during the process, and the process is simple, easy to operate, and the preparation cost is low, thus enabling industrial production. The MnNiCuPt (La, Mo, Co, V, Ti) high-entropy alloy catalyst prepared by the present invention exhibits excellent water electrolysis performance, which not only reduces the catalyst cost but also improves the catalytic performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0023] Figure 1 : This is a scanning electron microscope (SEM) photograph of the MnNiCuPt (La, Mo, Co, V, Ti) high entropy alloy prepared in the example;

[0024] Figure 2The X-ray diffraction (XRD) pattern of the MnNiCuPt (La, Mo, Co, V, Ti) high entropy alloy prepared in Example;

[0025] Figure 3 Linear sweep voltammetry (LSV) curves and Tafel slope plots of the MnNiCuPt (La, Mo, Co, V, Ti) high entropy alloy prepared in Example 1 and the comparative example RuO2 when used as catalysts for oxygen evolution in water electrolysis;

[0026] Figure 4 Linear sweep voltammetry (LSV) curves and Tafel slope plots of the MnNiCuPt (La, Mo, Co, V, Ti) high entropy alloy prepared in Example 1 and Pt in Comparative Example 2 when used as catalysts for hydrogen evolution in water electrolysis;

[0027] Figure 5 When the MnNiCuPtMo high entropy alloy prepared in the embodiment is used as a catalyst for oxygen evolution in electrolysis of water, the 2 Vt diagram under constant current density.

[0028] Figure 6 When the MnNiCuPtMo high entropy alloy prepared in the embodiment is used as a catalyst for hydrogen evolution in water electrolysis, the 2 Vt diagram under constant current density.

[0029] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0030] The following will be a clear and complete description of the technical solutions in the embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0031] This invention proposes a low-Pt high-entropy alloy water electrolysis catalyst, its preparation method, and its application. High-entropy alloys (HEAs) have come into the public eye due to their complex functional properties. HEAs are a new type of multi-component material composed of multiple elements in equal or near-equal molar ratios, breaking with traditional material design concepts. Their unique crystal structure exhibits many structural and performance characteristics that differ from traditional materials. Currently, a variety of high-entropy materials have been developed both domestically and internationally. These materials possess unique advantages in mechanical, physical, and chemical properties, and have enormous application potential in many fields. They have become a major research hotspot in the international materials science community.

[0032] According to one aspect of the present invention, the present invention provides the following technical solutions:

[0033] A method for preparing a low-Pt high-entropy alloy water electrolysis catalyst, wherein the low-Pt high-entropy alloy is MnNiCuPt (La, Mo, Co, V, Ti), comprising the following steps:

[0034] S1. Prepare any one of La, Mo, Co, V, Ti and Mn, Ni, Cu, Pt as metal elements according to the high entropy alloy ratio, and perform surface pretreatment on the metal elements before use;

[0035] S2. Place metal elements Mn, Ni, Cu, and Pt in one water-cooled crucible, and place any one of metal elements La, Mo, Co, V, and Ti in another water-cooled crucible, and place both water-cooled crucibles in a vacuum arc melting furnace that has been evacuated and filled with an inert protective gas.

[0036] S3. Inert gas is continuously introduced during the arc melting process, and electromagnetic stirring is also performed during the arc melting process. After cooling, a sample is obtained, and then the sample is remelted multiple times. After the last remelting, it is cooled to obtain a MnNiCuPt (La, Mo, Co, V, Ti) high entropy alloy water electrolysis catalyst.

[0037] Preferably, in step S1, the surface pretreatment is to remove impurities and oxides on the surface of the metal element, and then use acetone as a cleaning solvent to vibrate and clean the metal element under the action of ultrasound for 4 to 6 minutes. Specifically, the time for vibrating and cleaning the metal element under the action of ultrasound can be, for example but not limited to, any one of 4 minutes, 4.5 minutes, 5 minutes, 5.5 minutes, and 6 minutes, or a range between any two thereof; the power density of the ultrasound is 0.75 to 0.85 W / cm 2 , with a frequency of 30 to 35 Hz. Specifically, the power density of the ultrasound can be, for example but not limited to, 0.75 W / cm 2 , 0.76W / cm 2 , 0.77W / cm 2 , 0.78W / cm 2 , 0.79W / cm 2 , 0.80W / cm 2 , 0.81W / cm 2 , 0.82W / cm 2 , 0.83W / cm 2 , 0.84W / cm 2 , 0.85W / cm 2any one of or a range between any two of; the frequency may be, for example but not limited to, any one of 30 Hz, 31 Hz, 32 Hz, 33 Hz, 34 Hz, 35 Hz or a range between any two of;

[0038] Preferably, in step S2, the inert protective gas is introduced after vacuuming: when the vacuum reaches 2×10 -3 After reaching 5 Pa, argon protective gas was introduced.

[0039] Preferably, in step S3, when the sample is remelted multiple times, the sample is turned over each time it is remelted, and is cooled after the remelting is completed to remove the surface oxide layer of the sample.

[0040] Preferably, in step S3, the arc melting current is 60-100A, and the arc melting time is 30 minutes. Specifically, the arc melting current can be, for example but not limited to, any one of 60A, 70A, 80A, 90A, 100A, or a range between any two thereof;

[0041] Preferably, in step S3, the number of remelting is 3 to 5 times, and the time for maintaining the alloy liquid in a molten state during each remelting is 20 to 30 minutes. The number of remelting times can be, for example but not limited to, any one of 3, 4, 5 times, or a range between any two of them;

[0042] According to another aspect of the present invention, the present invention provides the following technical solutions:

[0043] A low-Pt high-entropy alloy water electrolysis catalyst is prepared by the above method, wherein the low-Pt high-entropy alloy is MnNiCuPt (La, Mo, Co, V, Ti).

[0044] As a preferred embodiment of the low-Pt high-entropy alloy water electrolysis catalyst described in the present invention, the following comprises, in atomic percentage, 20% Mn, 20% Ni, 20% Cu, 20% Pt, and 20% of any one of La, Mo, Co, V, and Ti.

[0045] An application of the above-mentioned low-Pt high-entropy alloy water electrolysis catalyst in the field of water electrolysis.

[0046] The technical solution of the present invention is further described below with reference to specific embodiments.

[0047] Example 1

[0048] This embodiment provides a method for preparing a low-Pt high-entropy alloy water electrolysis catalyst, comprising the following steps:

[0049] S1. Prepare metal elements Mn 20%, Ni 20%, Cu 20%, Pt 20%, and La 20% according to atomic percentage.

[0050] Metal surface pretreatment: Use mechanical assistance such as grinding wheel or manual grinding to remove impurities and oxides on the surface of metal elements Mn, Ni, Cu, Pt, La, and then use acetone as a cleaning solvent to clean the metal elements Mn, Ni, Cu, Pt, La at a power density of 0.8W / cm 2 , clean in ultrasonic waves at a frequency of 33 Hz for 5 minutes and set aside;

[0051] S2, place the metal elements Mn, Ni, Cu, and Pt in one water-cooled crucible, and place La in another water-cooled crucible. Both of the water-cooled copper crucibles are placed in the furnace chamber of a non-consumable vacuum arc melting furnace, and evacuate to 2×10 -3 Pa and then backfill with inert gas argon to 5Pa;

[0052] S3. Arc melting of metal elements Mn, Ni, Cu, Pt, and La is performed under argon protection, with electromagnetic stirring during the arc melting process to increase the uniformity of alloy mixing. The arc melting current is 60 A and the melting time is 1 min. After arc melting, the thin slice sample is cooled to obtain a thin slice sample; the obtained thin slice sample is remelted four times, and the sample is turned over before each remelting, and the alloy liquid is kept in a molten state for 2 minutes during the remelting process; after multiple remelting, the thin slice is cooled to obtain a thin slice with a thickness of about 8 mm and a length and width of about 10 mm, and the surface oxide layer is further ground off by a grinder. After cooling, a MnNiCuPtLa high entropy alloy catalyst is obtained.

[0053] Example 2

[0054] This embodiment provides a method for preparing a low-Pt high-entropy alloy water electrolysis catalyst, comprising the following steps:

[0055] S1. Prepare metal elements Mn 20%, Ni 20%, Cu 20%, Pt 20%, and Mo 20% according to atomic percentage.

[0056] Metal surface pretreatment: Use mechanical assistance such as grinding wheel or manual grinding to remove impurities and oxides on the surface of metal elements Mn, Ni, Cu, Pt, Mo, and then use acetone as a cleaning solvent to clean the metal elements Mn, Ni, Cu, Pt, Mo at a power density of 0.8W / cm 2 , clean in ultrasonic waves at a frequency of 33 Hz for 5 minutes and set aside;

[0057] S2, place the metal elements Mn, Ni, Cu, and Pt in one water-cooled crucible, and place Mo in another water-cooled crucible. Both of the water-cooled copper crucibles are placed in the furnace chamber of a non-consumable vacuum arc melting furnace, and evacuate to 2×10 -3 Pa and then backfill with inert gas argon to 5Pa;

[0058] S3. Arc melting of metal elements Mn, Ni, Cu, Pt, and Mo is performed under argon protection, with electromagnetic stirring accompanying the arc melting to increase the uniformity of alloy mixing. The arc melting current is 60 A and the melting time is 1 min. After arc melting, the thin slice sample is cooled to obtain a thin slice sample. The obtained thin slice sample is remelted four times, and the sample is turned over before each remelting. The alloy liquid is kept in a molten state for 2 min during the remelting process. After multiple remeltings, the thin slice is cooled to obtain a thin slice with a thickness of about 8 mm and a length and width of about 10 mm. The surface oxide layer is further ground off by a grinder, and the MnNiCuPtMo high entropy alloy catalyst is obtained after cooling.

[0059] Example 3

[0060] This embodiment provides a method for preparing a low-Pt high-entropy alloy water electrolysis catalyst, comprising the following steps:

[0061] S1. Prepare metal elements Mn 20%, Ni 20%, Cu 20%, Pt 20%, and Co 20% according to atomic percentage.

[0062] Metal surface pretreatment: Use mechanical auxiliary methods such as grinding wheels or manual grinding to remove impurities and oxides on the surface of metal elements Mn, Ni, Cu, Pt, and Co. Then use acetone as a cleaning solvent to clean the metal elements Mn, Ni, Cu, Pt, and Co at a power density of 0.8W / cm 2 , clean in ultrasonic waves at a frequency of 33 Hz for 5 minutes and set aside;

[0063] S2, place the metal elements Mn, Ni, Cu, and Pt in one water-cooled crucible, and place Co in another water-cooled crucible. Both of the water-cooled copper crucibles are placed in the furnace chamber of a non-consumable vacuum arc melting furnace, and evacuate to 2×10 -3 Pa and then backfill with inert gas argon to 5Pa;

[0064] S3. Arc melting of metal elements Mn, Ni, Cu, Pt, and Co is performed under argon protection, with electromagnetic stirring during the arc melting process to increase the uniformity of alloy mixing. The arc melting current is 60 A and the melting time is 1 min. After arc melting, the thin slice sample is cooled to obtain a thin slice sample. The obtained thin slice sample is remelted four times, and the sample is turned over before each remelting. The alloy liquid is kept in a molten state for 2 minutes during the remelting process. After multiple remeltings, the thin slice is cooled to obtain a thin slice with a thickness of about 8 mm and a length and width of about 10 mm. The surface oxide layer is further ground off by a grinder, and the MnNiCuPtCo high entropy alloy catalyst is obtained after cooling.

[0065] Example 4

[0066] This embodiment provides a method for preparing a low-Pt high-entropy alloy water electrolysis catalyst, comprising the following steps:

[0067] S1. Prepare metal elements Mn 20%, Ni 20%, Cu 20%, Pt 20%, and V 20% according to atomic percentage.

[0068] Metal surface pretreatment: Use mechanical auxiliary methods such as grinding wheels or manual grinding to remove impurities and oxides on the surface of metal elements Mn, Ni, Cu, Pt, and V. Then use acetone as a cleaning solvent to clean the metal elements Mn, Ni, Cu, Pt, and V at a power density of 0.8W / cm 2 , clean in ultrasonic waves at a frequency of 33 Hz for 5 minutes and set aside;

[0069] S2, place the metal elements Mn, Ni, Cu, and Pt in a water-cooled crucible, and place V in another water-cooled crucible. Both of the water-cooled copper crucibles are placed in the furnace chamber of a non-consumable vacuum arc melting furnace, and evacuate to 2×10 -3 Pa and then backfill with inert gas argon to 5Pa;

[0070] S3. Arc melting of metal elements Mn, Ni, Cu, Pt, and V is performed under argon protection, with electromagnetic stirring during the arc melting process to increase the uniformity of alloy mixing. The arc melting current is 60A and the melting time is 1 min. After arc melting, the thin slice sample is cooled to obtain a thin slice sample. The obtained thin slice sample is remelted four times, and the sample is turned over before each remelting. The alloy liquid is kept in a molten state for 2 minutes during the remelting process. After multiple remeltings, the thin slice is cooled to obtain a thin slice with a thickness of about 8 mm and a length and width of about 10 mm. The surface oxide layer is further ground off by a grinder, and the MnNiCuPtV high entropy alloy catalyst is obtained after cooling.

[0071] Example 5

[0072] This embodiment provides a method for preparing a low-Pt high-entropy alloy water electrolysis catalyst, comprising the following steps:

[0073] S1. Prepare metal elements Mn 20%, Ni 20%, Cu 20%, Pt 20%, and Ti 20% according to atomic percentage.

[0074] Metal surface pretreatment: Use mechanical auxiliary methods such as grinding wheels or manual grinding to remove impurities and oxides on the surface of metal elements Mn, Ni, Cu, Pt, and Ti, and then use acetone as a cleaning solvent to clean the metal elements Mn, Ni, Cu, Pt, and Ti at a power density of 0.8W / cm 2 , clean in ultrasonic waves at a frequency of 33 Hz for 5 minutes and set aside;

[0075] S2, place the metal elements Mn, Ni, Cu, and Pt in one water-cooled crucible, place Ti in another water-cooled crucible, and place both water-cooled copper crucibles in the furnace chamber of a non-consumable vacuum arc melting furnace, and evacuate to 2×10 -3 Pa and then backfill with inert gas argon to 5Pa;

[0076] S3. Arc melting of metal elements Mn, Ni, Cu, Pt, and Ti is performed under argon protection, with electromagnetic stirring accompanying the arc melting to increase the uniformity of alloy mixing. The arc melting current is 60 A and the melting time is 1 min. After arc melting, the thin slice sample is cooled to obtain a thin slice sample. The obtained thin slice sample is remelted four times, and the sample is turned over before each remelting. The alloy liquid is kept in a molten state for 2 minutes during the remelting process. After multiple remeltings, the thin slice is cooled to obtain a thin slice with a thickness of about 8 mm and a length and width of about 10 mm. The surface oxide layer is further ground off by a grinder, and the MnNiCuPtTi high entropy alloy catalyst is obtained after cooling.

[0077] Performance testing:

[0078] The MnNiCuPtLa, MnNiCuPtMo, MnNiCuPtCo, MnNiCuPtV, and MnNiCuPtTi water electrolysis catalysts prepared in Examples 1-5 of the present invention were tested for their oxygen evolution and hydrogen evolution properties. The catalytic performance of the prepared electrodes for water electrolysis oxygen evolution and hydrogen evolution was tested using an electrochemical workstation. A three-electrode system was adopted, in which the counter electrode was a platinum sheet electrode, the reference electrode was an Ag / AgCl electrode, and the electrolyte was a KOH aqueous solution with a concentration of 1 mol / L.

[0079] like Figure 1The SEM photos and energy spectrum of MnNiCuPtLa, MnNiCuPtMo, MnNiCuPtCo, MnNiCuPtV, and MnNiCuPtTi water electrolysis oxygen evolution catalysts prepared in Examples 1-5 are shown. It can be seen from the SEM photos that PtNiMnCuCo ( Figure 1 (d)), PtNiMnCuV( Figure 1 (e)), PtNiMnCuTi( Figure 1 The surface of the catalyst in (f) is relatively flat and dense, and the contact area with the electrolyte solution is relatively reduced during the catalytic process, which is not conducive to the catalytic reaction. Figure 1 For the catalyst (a), the surface before catalysis is relatively loose, and a discontinuous layered structure can be found on the surface by careful observation. Figure 1 The surface of the catalyst in (b) and (c) is relatively loose and presents an uneven distribution of small agglomerates. After magnification, it can be clearly observed that it has a hexagonal structure, which can increase the specific surface area of ​​the catalyst.

[0080] Figure 2 The XRD patterns revealed that PtNiMnCuTi, PtNiMnCuLa, PtNiMnCuMo, PtNiMnCuCo, and PtNiMnCuV were all crystalline. The XRD patterns of PtNiMnCuMo, PtNiMnCuCo, and PtNiMnCuV showed three visible peaks at 2θ = 43.5°, 49.8°, and 74.3°, which can be attributed to the FCC structures of (111), (200), and (220), indicating that PtNiMnCuCo and PtNiMnCuV were single-phase FCC structures. The XRD patterns of PtNiMnCuMo, PtNiMnCuTi, and PtNiMnCuLa showed two shoulder peaks at 2θ ≈ 42° and 74°, which were fitted to the Mo BCC PDF#42-1120 structure. Therefore, PtNiMnCuMo is a catalyst with a predominantly FCC structure and a small amount of BCC structure. Its main FCC lattice structure shows a slight shift in peak position relative to the standard peak of Fe FCC phase (PDF#52–0513), indicating that the difference in atomic diameters of the five elements leads to lattice distortion and increases the activation energy.

[0081] Figure 3 a) is the linear sweep voltammetry (LSV) curve of MnNiCuPtLa, MnNiCuPtMo, MnNiCuPtCo, MnNiCuPtV, and MnNiCuPtTi prepared in Examples 1-5 when used as catalysts for oxygen evolution by electrolysis of water. The OER performance is 10 mA / cm 2The order of places is as follows:

[0082] PtNiMnCuMo>PtNiMnCuCo>RuO2>PtNiMnCuV>PtNiMnCuTi>PtNiMnCuLa. Figure 3 b) Tafel slope data show that PtNiMnCuMo has the lowest Tafel slope, which indicates that this group of samples requires the smallest overpotential to reach the required current density and is more kinetically advantageous.

[0083] Figure 4 In a), MnNiCuPtLa, MnNiCuPtMo, MnNiCuPtCo, MnNiCuPtV and MnNiCuPtTi prepared in Examples 1-5 are used as LSV curves of electrolytic water oxygen evolution catalysts. The overpotential (η) required for PtNiMnCuMo is 41 mV, which is much lower than that of PtNiMnCuCo (235 mV), PtNiMnCuV (180 mV) and PtNiMnCuTi (140 mV), indicating that PtNiMnCuMo has better HER catalytic activity. The Tafel slope diagram (such as Figure 4 As shown in (b), the Tafel slope of PtNiMnCuMo is 40 mV / dec, which is lower than that of PtNiMnCuLa (89.8 mV / dec) and Pt (116.3 mV / dec). This result indicates that PtNiMnCuMo has the fastest HER reaction kinetics, indicating the fastest increase in current density, indicating that PtNiMnCuMo has high catalytic activity, which is consistent with its lowest overpotential.

[0084] Figure 5 For the long-term OER stability test of Example PtNiMnCuMo, at 200mA / cm 2 The electrocatalytic stability of PtNiMnCuMo was tested at a high current density. The voltage drop was very small after 48h OER, indicating that the stability of PtNiMnCuMo catalysts in alkaline solutions was very excellent.

[0085] Figure 6 For the long-term HER stability test of Example PtNiMnCuMo, at 200mA / cm 2 The electrocatalytic stability of PtNiMnCuMo was tested at a high current density. After 48h HER, PtNiMnCuMo only showed a negligible overpotential drop of about 10mV, indicating that it has excellent durability, which can ensure the long-term and effective operation of the catalyst in alkaline environment. This shows that the PtNiMnCuMo high-entropy alloy electrocatalyst has excellent full water splitting performance and excellent stability.

[0086] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a low-Pt high-entropy alloy water electrolysis catalyst, characterized in that: The low-Pt high-entropy alloy is MnNiCuPt(La, Mo, V, Ti), which contains, in atomic percentage, 20% Mn, 20% Ni, 20% Cu, 20% Pt, and 20% of any one of La, Mo, V, and Ti; comprising the following steps: S1. Prepare any one of La, Mo, V, Ti and Mn, Ni, Cu, Pt as metal elements according to the high entropy alloy ratio, and perform surface pretreatment on the metal elements before use; S2. Place metal elements Mn, Ni, Cu, and Pt in one water-cooled crucible, and place any one of metal elements La, Mo, V, and Ti in another water-cooled crucible. Place both water-cooled crucibles in a vacuum arc melting furnace that has been evacuated and filled with an inert protective gas. S3. Inert gas is continuously introduced during the arc melting process, and electromagnetic stirring is also performed during the arc melting process. After cooling, a sample is obtained, and then the sample is remelted multiple times. After the last remelting, the sample is cooled to obtain a MnNiCuPt (La, Mo, V, Ti) high entropy alloy water electrolysis catalyst.

2. The method for preparing a low-Pt high-entropy alloy water electrolysis catalyst according to claim 1, wherein In step S1, the surface pretreatment is to remove impurities and oxides on the surface of the metal element, and then use acetone as a cleaning solvent to vibrate and clean the metal element under the action of ultrasound for 4 to 6 minutes.

3. The method for preparing a low-Pt high-entropy alloy water electrolysis catalyst according to claim 2, wherein: In step S1, the power density of the ultrasound is 0.75-0.85 W / cm 2 , frequency is 30~35 Hz.

4. The method for preparing a low-Pt high-entropy alloy water electrolysis catalyst according to claim 1, wherein: In step S2, the inert protective gas is introduced after vacuuming: 10 -3 After reaching 5 Pa, argon protective gas was introduced.

5. The method for preparing a low-Pt high-entropy alloy water electrolysis catalyst according to claim 1, wherein: In step S3, when the sample is remelted multiple times, the sample is turned over each time it is remelted, and is cooled after the remelting is completed to remove the surface oxide layer of the sample.

6. The method for preparing a low-Pt high-entropy alloy water electrolysis catalyst according to claim 1, wherein: In step S3, the arc melting current is 60-100 A, and the arc melting time is 30 min.

7. The method for preparing a low-Pt high-entropy alloy water electrolysis catalyst according to claim 5, wherein: In step S3, the number of remelting is 3 to 5 times, and the time for maintaining the alloy liquid in a molten state for each remelting is 2 to 3 minutes.

8. A low-Pt high-entropy alloy water electrolysis catalyst, characterized in that The preparation method is described in any one of claims 1 to 7.

9. Use of the low-Pt high-entropy alloy water electrolysis catalyst according to claim 8 in the field of water electrolysis.

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