Foamed Ni-high-entropy alloy catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the field of new energy and water electrolysis hydrogen production, and relates to a foamed Ni-high-entropy alloy catalyst and a preparation method and application thereof. The foam Ni-high-entropy alloy catalyst comprises foam Ni, a high-entropy alloy and metal Ni, wherein the high-entropy alloy and the metal Ni are loaded on the surface of the foam Ni, and according to the foam Ni-high-entropy alloy catalyst, the foam Ni and the high-entropy alloy are integrated through the metal Ni. The preparation method comprises the following steps that high-entropy alloy metal powder and Ni metal powder are added into a wet mixing agent A to be subjected to first-time ball-milling mixing, and a mixture A is obtained; adding a wet mixing agent B into the mixture A, mixing, carrying out secondary ball-milling mixing to obtain a mixture B, filtering the mixture B, and reserving a liquid part to obtain an impregnation liquid; soaking foamed nickel in the steeping liquor, and then drying and sintering to obtain the foamed nickel-high-entropy alloy catalyst. The preparation method provided by the invention is simple to operate, and saves time and economic cost.

Description

Technical Field

[0001] The present invention belongs to the fields of new energy and hydrogen production by electrolyzing water, and relates to a foam Ni-high entropy alloy catalyst, a preparation method thereof and an application thereof. Background Art

[0002] Hydrogen energy is an indispensable part of the blueprint for the sustainable development of the future energy environment. How to efficiently produce and use hydrogen has become a key issue. Designing active, stable and low-cost catalysts is the key to the next-generation energy storage technology.

[0003] The hydrogen production process by electrolyzing water mainly consists of two half-reactions: the hydrogen evolution reaction at the cathode and the oxygen evolution reaction at the anode. Among them, the oxygen evolution reaction has a kinetic lag due to the four-electron transfer process, which greatly increases the overpotential of electrolyzing water. Therefore, researchers are committed to developing efficient electrocatalysts to reduce the overpotential of the oxygen evolution reaction and promote the progress of this reaction. Among them, noble metal Ir-based and Ru-based catalysts show excellent performance in catalyzing the oxygen evolution reaction due to their inherent high activity, but the high price and scarcity limit the widespread industrial application of such noble metals. At present, nickel foam is a commonly used non-noble metal oxygen evolution reaction catalyst, which has a low cost but insufficient catalytic activity. High entropy alloys composed of non-noble metals have excellent properties and low costs, and have received extensive attention in the application of oxygen evolution reaction (OER) catalysts due to their many advantages. However, such catalysts have problems of low utilization rate and limited activity. Summary of the Invention

[0004] In view of this, the present invention provides a foam Ni-high entropy alloy catalyst, a preparation method thereof and an application thereof, combining nickel foam and high entropy alloy, and utilizing the advantages of both to overcome the low activity problem of existing nickel foam as an oxygen evolution catalyst.

[0005] The present invention combines low-cost nickel foam and high entropy alloy composed of non-noble metals, and high-entropizes on the basis of nickel foam to obtain porous high entropy alloy, fully utilizing the pore structure of nickel foam to improve the catalytic activity of nickel foam, and at the same time improving the activity and catalytic performance of high entropy alloy composed of non-noble metals.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions.

[0007] According to the first aspect of the present invention, there is provided a foam Ni-high entropy alloy catalyst, the foam Ni-high entropy alloy catalyst comprising nickel foam, high entropy alloy and metallic Ni; wherein, the high entropy alloy and metallic Ni are loaded on the surface of nickel foam, and the foam Ni-high entropy alloy catalyst integrates nickel foam and high entropy alloy through metallic Ni.

[0008] For the above-mentioned Ni foam-high entropy alloy catalyst, the mass fraction of metallic Ni supported on the surface of Ni foam is 20-40%.

[0009] For the above-mentioned Ni foam-high entropy alloy catalyst, the high entropy alloy includes FeCoNiCrM, where M includes at least one of Mn and Mo.

[0010] For the above-mentioned Ni foam-high entropy alloy catalyst, in the high entropy alloy, the molar ratio of Fe, Co, Cr, and M is 1:1:1:1.

[0011] For the above-mentioned Ni foam-high entropy alloy catalyst, in the high entropy alloy, the molar ratio of Fe, Co, Ni, Cr, and M is 3:3:8:3:3.

[0012] According to the second aspect of the present invention, there is provided a method for preparing the above-mentioned Ni foam-high entropy alloy catalyst, including the following steps:

[0013] 1) Prepare wet mixture A;

[0014] 2) Add high entropy alloy metal powder and Ni metal powder to wet mixture A for the first ball milling and mixing to obtain mixture A;

[0015] 3) Add wet mixture B to mixture A, mix and then perform the second ball milling and mixing to obtain mixture B, and filter mixture B to retain the liquid part to obtain the impregnation solution;

[0016] 4) Immerse Ni foam in the impregnation solution obtained in step 3), then dry it, and sinter it to obtain the Ni foam-high entropy alloy catalyst.

[0017] In the present invention, adding high entropy alloy metal powder and Ni metal powder to wet mixture A for the first ball milling and mixing aims to create a concentration difference between the spherical particles of different metal powders, so that atomic exchange can occur during subsequent sintering to integrate them into one body.

[0018] In the present invention, a binder is used to bond metal particles to the surface of Ni foam, and then the organic matter is removed by sintering, so that the metal particles and Ni foam are combined into one body, and finally the Ni foam-high entropy alloy catalyst is formed.

[0019] In the method for preparing the above-mentioned Ni foam-high entropy alloy catalyst, in step 1), wet mixture A includes ethanol, ethyl acetate, and triethanolamine.

[0020] In the method for preparing the above-mentioned Ni foam-high entropy alloy catalyst, in step 1), in wet mixture A, the mass ratio of ethanol, ethyl acetate, and triethanolamine is 4.8-5.2:2.8-3.2:1.

[0021] In the present invention, ethanol and ethyl acetate are miscible and can volatilize together in this proportion, serving as the basic components of the solvent; triethanolamine is used as a dispersant, enabling metal particles insoluble in ethanol and ethyl acetate to be uniformly dispersed in the solvent.

[0022] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 2), the mass ratio of the high entropy alloy to the Ni metal powder is 3.8 - 4.2:1.

[0023] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 2), the high entropy alloy includes FeCoNiCrM, where M includes at least one of Mn and Mo.

[0024] The present invention uses a high entropy alloy:Ni powder ratio of 3.8 - 4.2:1, preferably 4:1, which is beneficial for the surface composition of the obtained catalyst to be Fe:Co:Ni:Cr:M = 15:15:40:15:15 (i.e., 3:3:8:3:3), thereby forming a high entropy alloy. When the proportion of Ni powder decreases, it may lead to uneven mixing during the mixing process and result in an uneven catalyst.

[0025] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 2), the particle size of the metal powder of the high entropy alloy is < 20 μm.

[0026] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 2), the particle size of the Ni metal powder is < 20 μm.

[0027] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 2), the rotation speed of the first ball milling and mixing is 100 - 500 r / min.

[0028] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 2), the time of the first ball milling and mixing is 20 - 50 h.

[0029] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 2), the particle size of the ball milling beads used in the first ball milling and mixing is 0.5 cm - 3 cm.

[0030] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 2), the ball milling beads in the first milling and mixing include zirconia ceramic balls.

[0031] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 3), the wet mixing agent B includes polyvinyl butyral (PVB), polyethylene glycol, ethanol, and ethyl acetate.

[0032] In the present invention, polyvinyl butyral (PVB) is a solid powder, which acts as a binder to assist in binding metal particles together. Polyethylene glycol is a plasticizer that acts together with PVB. Ethanol and ethyl acetate are used to adjust the consistency. The purpose of adding them here is to enable the various components after mixing to adhere uniformly to the surface of nickel foam in a solid state after drying.

[0033] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 3), in the wet mixer B, the mass ratio of PVB, polyethylene glycol, ethanol and ethyl acetate is 4.8 - 5.2:1:2.3 - 2.7:2.3 - 2.7.

[0034] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 3), adding the wet mixer B to the mixture A specifically includes adding the components in the wet mixer B to the ball-milled mixture A in batches separately.

[0035] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 3), the rotation speed of the second ball milling and mixing is 100 - 500 r / min.

[0036] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 3), the time of the second ball milling and mixing is 20 - 50 h.

[0037] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 4), the nickel foam is pretreated before soaking, and the pretreatment includes degreasing with acetone, washing with water, and soaking and washing with 3M hydrochloric acid.

[0038] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 4), the soaking time of the nickel foam in the impregnation solution is 1 - 10 min.

[0039] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 4), the drying temperature is 45 - 60 °C.

[0040] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 4), the sintering temperature is 900 - 1100 °C.

[0041] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 4), the sintering time is 1 - 5 h.

[0042] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 4), the sintering is carried out in a nitrogen-hydrogen mixed gas.

[0043] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 4), the sintering is carried out in a mixed gas of N2-5% H2.

[0044] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 4), the sintering adopts a multi-stage heating mode.

[0045] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 4), the multi-stage heating mode of the sintering includes: the first-stage heating, the second-stage heating, the third-stage heating, the fourth-stage heating, and the fifth-stage heating.

[0046] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 4), in the sintering, the heating rate of the first-stage heating is greater than the heating rates of the second-stage heating, the third-stage heating, the fourth-stage heating, and the fifth-stage heating.

[0047] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 4), in the sintering, the heating rates of the second-stage heating and the third-stage heating may be the same or different.

[0048] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 4), in the sintering, the heating rates of the fourth-stage heating and the fifth-stage heating may be the same or different.

[0049] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 4), in the sintering, the heating rates of the fourth-stage heating and the fifth-stage heating are greater than the heating rates of the second-stage heating and the third-stage heating.

[0050] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 4), the first-stage heating is carried out at a heating rate of 0.9-1.3 °C / min to 90-110 °C, and then kept warm for 80-120 min.

[0051] In the preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, in step 4), the second-stage heating is carried out at a heating rate of 0.3-0.5 °C / min to 180-220 °C, and kept warm for 300-400 min.

[0052] In some specific embodiments of the second aspect of the present invention, in step 4), the third-stage heating is carried out at a heating rate of 0.3-0.5 °C / min to 280-300 °C.

[0053] In some specific embodiments of the second aspect of the present invention, in step 4), the temperature is raised in the fourth stage at a heating rate of 0.45 to 0.7 °C / min to 580 to 620 °C and held for 600 to 700 min.

[0054] In some specific embodiments of the second aspect of the present invention, in step 4), the temperature is raised in the fourth stage at a heating rate of 0.45 to 0.7 °C / min (for example, 0.50 °C / min, 0.55 °C / min, 0.60 °C / min or 0.65 °C / min) to 880 to 1000 °C and held for 750 to 900 min.

[0055] The purpose of the stepwise temperature increase in the present invention is to obtain the following sample surface: a sample surface in which a mixture of various organic substances and two metal powders is attached to nickel foam. Among them, the temperature increase below 300 °C is to decompose various components and blow them away with the airflow; the temperature after subsequent heating is relatively high, but this temperature still does not reach the melting point of the high-entropy alloy, and its purpose is to make the metal powders fuse with each other at high temperature.

[0056] The purpose of the present invention is to provide a method for preparing high-entropy nickel foam and its application in electrolytic water hydrogen production, so as to obtain an oxygen evolution catalyst with simple preparation and high catalytic activity.

[0057] In the present invention, by uniformly mixing high-entropy alloy metal powder and Ni metal powder in an organic solvent, soaking nickel foam in it and then sintering, an integrated nickel foam-high entropy alloy catalyst is obtained. Among them, since both the high-entropy alloy and Ni metal are loaded in the nickel foam after soaking, and the high-entropy alloy such as FeCoNiCrMn or FeCoNiCrMo contains metal Ni element, during the high-temperature sintering process, the presence of Ni metal powder enables the high-entropy alloy and nickel foam to be easily combined together and can enhance the bonding strength between the two, thus realizing the integration of the nickel foam-high entropy alloy catalyst.

[0058] According to the third aspect of the present invention, there is provided an application of the above-mentioned foam Ni-high entropy alloy catalyst as an oxygen evolution reaction catalyst or an oxygen evolution reaction electrode in the field of electrolytic water hydrogen production.

[0059] In the above application, when the foam Ni-high entropy alloy catalyst is in a 1 mol / L KOH alkaline solution and the current density is 10 mA / cm -2 ², the overpotential of the oxygen evolution reaction can be reduced to 238 mV.

[0060] In the present invention, without conflict, the above technical features can be freely combined to form new technical solutions.

[0061] The above technical solution provided by the embodiments of the present invention has the following advantages compared with the prior art:

[0062] (1) The preparation method of the foam Ni-high entropy alloy catalyst according to the present invention is simple in operation, greatly saving time and economic costs;

[0063] (2) By adopting different high entropy alloy composition designs (such as FeCoNiCrMn or FeCoNiCrMo, etc.) in the present invention, the overpotential of the oxygen evolution reaction is greatly reduced, and the oxygen evolution activity of the catalyst is improved;

[0064] (3) The technical solution of the present invention provides a research direction for further developing catalysts combining foam substrate materials and high entropy alloys in the future. For example, high entropy alloys with various other different compositions can be loaded on nickel foam and iron foam. Description of the Drawings

[0065] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with the present invention and used together with the specification to explain the principles of the present invention.

[0066] Figure 1 SEM image of the foam Ni-high entropy alloy catalyst prepared in Example 1 of the present invention.

[0067] Figure 2 SEM image of the foam Ni-high entropy alloy catalyst prepared in Example 2 of the present invention.

[0068] Figure 3 Linear sweep voltammetry (LSV) curve of the foam Ni-high entropy alloy catalysts prepared in Examples 1-2 of the present invention and the foam Ni in Comparative Example 1.

[0069] Figure 4 Linear sweep voltammetry (LSV) curve of the foam Ni-high entropy alloy catalyst prepared in Example 3 of the present invention.

[0070] Figure 5 SEM image of the foam Ni-high entropy alloy catalyst prepared in Comparative Example 2 of the present invention. Detailed Embodiments

[0071] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0072] Some embodiments according to the first aspect of the present invention provide a foamed Ni-high entropy alloy catalyst, which includes foamed Ni, high entropy alloy, and metallic Ni; wherein, the high entropy alloy and metallic Ni are loaded on the surface of the foamed Ni, and the foamed Ni-high entropy alloy catalyst integrates the foamed Ni and the high entropy alloy through the metallic Ni.

[0073] According to some embodiments of the first aspect of the present invention, the mass fraction of the metallic Ni loaded on the surface of the foamed Ni is 20-40% (for example, 22%, 25%, 28%, 30%, 35% or 38%).

[0074] According to some embodiments of the first aspect of the present invention, the high entropy alloy includes FeCoNiCrM, wherein M includes at least one of Mn and Mo.

[0075] According to some embodiments of the first aspect of the present invention, in the high entropy alloy, the molar ratio of Fe, Co, Cr, and M is 1:1:1:1.

[0076] According to some embodiments of the first aspect of the present invention, in the high entropy alloy, the molar ratio of Fe, Co, Ni, Cr, and M is 3:3:8:3:3.

[0077] Some specific embodiments according to the second aspect of the present invention provide a preparation method of a foamed Ni-high entropy alloy catalyst, which includes the following steps:

[0078] 1) Prepare wet mixture A;

[0079] 2) Add the high entropy alloy metal powder and Ni metal powder into the wet mixture A for the first ball milling and mixing to obtain mixture A;

[0080] 3) Add wet mixture B into mixture A, mix and then perform the second ball milling and mixing to obtain mixture B, and filter mixture B to retain the liquid part to obtain the impregnation solution;

[0081] 4) Immerse the foamed nickel in the impregnation solution obtained in step 3), then dry it, and sinter it to obtain the foamed nickel-high entropy alloy catalyst.

[0082] In some specific embodiments according to the second aspect of the present invention, in step 1), the wet mixture A includes ethanol, ethyl acetate, and triethanolamine.

[0083] In some specific embodiments according to the second aspect of the present invention, in step 1), in the wet mixture A, the mass ratio of ethanol, ethyl acetate, and triethanolamine is 4.8-5.2:2.8-3.2:1 (for example, 5:3:1).

[0084] In some specific embodiments of the second aspect of the present invention, in step 2), the mass ratio of the high-entropy alloy to the Ni metal powder is 3.8 to 4.2:1 (for example, 4:1).

[0085] In some specific embodiments of the second aspect of the present invention, in step 2), the high-entropy alloy includes FeCoNiCrM, where M includes at least one of Mn and Mo.

[0086] In some specific embodiments of the second aspect of the present invention, in step 2), the particle size of the high-entropy alloy metal powder is <20 μm (for example, 15 μm, 10 μm, 5 μm or 2 μm).

[0087] In some specific embodiments of the second aspect of the present invention, in step 2), the particle size of the Ni metal powder is <20 μm (for example, 15 μm, 10 μm, 5 μm or 2 μm).

[0088] In some specific embodiments of the second aspect of the present invention, in step 2), the rotation speed of the first ball milling and mixing is 100 to 500 r / min (for example, 150 r / min, 180 r / min, 200 r / min, 300 r / min or 400 r / min).

[0089] In some specific embodiments of the second aspect of the present invention, in step 2), the time of the first ball milling and mixing is 20 to 50 h (for example, 25 h, 30 h, 35 h, 40 h, 45 h or 48 h).

[0090] In some specific embodiments of the second aspect of the present invention, in step 2), the particle size of the ball milling beads used in the first ball milling and mixing is 0.5 cm - 3 cm.

[0091] In some specific embodiments of the second aspect of the present invention, in step 2), in the first ball milling and mixing, the ball milling beads include zirconia ceramic balls.

[0092] In some specific embodiments of the second aspect of the present invention, in step 3), the wet mixing agent B includes PVB, polyethylene glycol, ethanol and ethyl acetate.

[0093] In some specific embodiments of the second aspect of the present invention, in step 3), in the wet mixing agent B, the mass ratio of PVB, polyethylene glycol, ethanol and ethyl acetate is 4.8 to 5.2:1:2.3 to 2.7:2.3 to 2.7 (for example, 5:1:2.5:2.5).

[0094] In some specific embodiments of the second aspect of the present invention, in step 3), the rotation speed of the second ball milling and mixing is 100 - 500 r / min (for example, 150 r / min, 180 r / min, 200 r / min, 300 r / min or 400 r / min).

[0095] In some specific embodiments of the second aspect of the present invention, in step 3), the time of the second ball milling and mixing is 20 - 50 h (for example, 25 h, 30 h, 35 h, 40 h, 45 h or 48 h).

[0096] In some specific embodiments of the second aspect of the present invention, in step 4), the nickel foam is pretreated before soaking, and the pretreatment includes degreasing with acetone, washing with water, and soaking and washing with 3M hydrochloric acid.

[0097] In some specific embodiments of the second aspect of the present invention, in step 4), the soaking time of the nickel foam in the impregnating solution is 1 - 10 min (for example, 2 min, 3 min, 5 min or 8 min).

[0098] In some specific embodiments of the second aspect of the present invention, in step 4), the drying temperature is 45 - 60 °C (for example, 50 °C).

[0099] In some specific embodiments of the second aspect of the present invention, in step 4), the sintering temperature is 900 - 1100 °C (for example, 920 °C, 950 °C, 980 °C, 1000 °C or 1050 °C).

[0100] In some specific embodiments of the second aspect of the present invention, in step 4), the sintering time is 1 - 5 h (for example, 1.5 h, 2 h, 2.5 h, 3 h or 4 h).

[0101] In some specific embodiments of the second aspect of the present invention, in step 4), the sintering is carried out in a nitrogen - hydrogen mixed gas.

[0102] In some specific embodiments of the second aspect of the present invention, in step 4), the sintering is carried out in a mixed gas of N2 - 5% H2.

[0103] In some specific embodiments of the second aspect of the present invention, in step 4), the sintering adopts a multi - stage heating mode.

[0104] In some specific embodiments of the second aspect of the present invention, in step 4), the multi - stage heating mode of the sintering includes: the first - stage heating, the second - stage heating, the third - stage heating, the fourth - stage heating, and the fifth - stage heating.

[0105] In some specific embodiments of the second aspect of the present invention, in step 4), during the sintering, the heating rate of the first-stage heating is greater than the heating rates of the second-stage heating, the third-stage heating, the fourth-stage heating, and the fifth-stage heating.

[0106] In some specific embodiments of the second aspect of the present invention, in step 4), during the sintering, the heating rates of the second-stage heating and the third-stage heating may be the same or different.

[0107] In some specific embodiments of the second aspect of the present invention, in step 4), during the sintering, the heating rates of the fourth-stage heating and the fifth-stage heating may be the same or different.

[0108] In some specific embodiments of the second aspect of the present invention, in step 4), during the sintering, the heating rates of the fourth-stage heating and the fifth-stage heating are greater than the heating rates of the second-stage heating and the third-stage heating.

[0109] In some specific embodiments of the second aspect of the present invention, in step 4), during the first-stage heating, it is heated to 90-110 °C (for example, 100 °C) at a heating rate of 0.9-1.3 °C / min (for example, 1.0 °C / min, 1.1 °C / min, or 1.2 °C / min), and then held for 80-120 min (for example, 90 min, 100 min, or 110 min).

[0110] In some specific embodiments of the second aspect of the present invention, in step 4), during the second-stage heating, it is heated to 180-220 °C (for example, 190 °C, 200 °C, or 210 °C) at a heating rate of 0.3-0.5 °C / min (for example, 0.35 °C / min, 0.4 °C / min, or 0.45 °C / min), and held for 300-400 min (for example, 320 min, 340 min, 360 min, or 380 min).

[0111] In some specific embodiments of the second aspect of the present invention, in step 4), during the third-stage heating, it is heated to 280-320 °C (for example, 290 °C, 300 °C, or 310 °C) at a heating rate of 0.3-0.5 °C / min (for example, 0.35 °C / min, 0.4 °C / min, or 0.45 °C / min).

[0112] In some specific embodiments of the second aspect of the present invention, in step 4), the temperature is raised in the fourth stage at a heating rate of 0.45 to 0.7 °C / min (for example, 0.50 °C / min, 0.55 °C / min, 0.60 °C / min, or 0.65 °C / min) to 580 to 620 °C (for example, 590 °C, 600 °C, or 610 °C), and held for 600 to 700 min (for example, 620 min, 640 min, 660 min, or 680 min).

[0113] In some specific embodiments of the second aspect of the present invention, in step 4), the temperature is raised in the fourth stage at a heating rate of 0.45 to 0.7 °C / min (for example, 0.50 °C / min, 0.55 °C / min, 0.60 °C / min, or 0.65 °C / min) to 880 to 1000 °C (for example, 890 °C, 900 °C, 920 °C, 950 °C, 980 °C, or 990 °C), and held for 750 to 900 min (for example, 780 °C, 800 °C, 820 min, 840 min, 860 min, or 880 min).

[0114] Example 1

[0115] A preparation method of a foam Ni-high entropy alloy catalyst (FeCoNiCrMn-NF), the high entropy alloy is FeCoNiCrMn high entropy alloy, wherein in terms of molar ratio, Fe:Co:Ni:Cr:Mn = 15:15:40:15:15 (i.e., 3:3:8:3:3), and the preparation method includes the following steps:

[0116] Mix 15 g of ethanol, 9 g of ethyl acetate, and 3 g of triethanolamine, add them to a mixing bottle to obtain a mixed solution; take 40 g of high entropy alloy metal powder (particle size < 20 μm) and 10 g of Ni metal powder (particle size < 20 μm) according to the molar ratio Fe:Co:Ni:Cr:Mn = 1:1:1:1:1, and add them to the mixed solution; add 150 g of zirconia ceramic balls (diameter 0.5 cm - 3 cm) to the mixing bottle; after shaking and mixing evenly, place it on a ball mill, rotate at a speed of 180 r / min, and mix for 12 h;

[0117] Add 5 g of PVB, 1 g of polyethylene glycol, 2.5 g of ethanol, and 2.5 g of ethyl acetate to the mixing bottle; after shaking and mixing evenly, place it on a ball mill, rotate at a speed of 180 r / min, and mix for 48 h;

[0118] Conventional treatment of foam nickel: degrease with acetone, wash with water, soak in 3M hydrochloric acid and wash with water;

[0119] Filter and pour out the mixed liquid in the mixing bottle, soak the foam nickel in it for 3 min and then take it out, and dry it at 50 °C for 30 min;

[0120] The soaked nickel foam was heated to 950 °C in a tube furnace and sintered for 2 h; the atmosphere during sintering was a mixed gas of N2-5% H2. The heating procedure was as follows: heating to 100 °C at a heating rate of 1.1 °C / min, then holding for 100 min; then heating to 200 °C at a heating rate of 0.41 °C / min and holding for 360 min; then heating to 300 °C at a heating rate of 0.40 °C / min (corresponding to heating to 300 °C within 270 minutes); then heating to 600 °C at a heating rate of 0.53 °C / min (corresponding to heating to 600 °C within 570 minutes), holding at this temperature for 630 min; then heating to 950 °C at a heating rate of 0.50 °C / min (corresponding to heating to 950 °C within 700 minutes), holding at this temperature for 820 min; finally, cooling to room temperature in the furnace to obtain an integrated nickel foam high-entropy alloy, abbreviated as FeCoNiCrMn-NF.

[0121] Example 2

[0122] A preparation method of a foam Ni-high entropy alloy catalyst (FeCoNiCrMn-NF), the high entropy alloy is FeCoNiCrMn high entropy alloy, wherein in terms of molar ratio, Fe:Co:Ni:Cr:Mn = 15:15:40:15:15 (i.e., 3:3:8:3:3), and the preparation method includes the following steps:

[0123] Mix 15 g of ethanol, 9 g of ethyl acetate, and 3 g of triethanolamine, and add them to a mixing bottle to obtain a mixed solution; take 40 g of FeCoNiCrMo high entropy alloy metal powder (particle size < 20 μm) and 10 g of Ni metal powder (particle size < 20 μm) according to the molar ratio Fe:Co:Ni:Cr:Mn = 1:1:1:1:1, and add them to the mixed solution; add 150 g of zirconia ceramic balls (diameter 0.5 cm - 3 cm) to the mixing bottle; after shaking and mixing evenly, place it on a ball mill, rotate at 180 r / min, and mix for 12 h;

[0124] Add 5 g of PVB, 1 g of polyethylene glycol, 2.5 g of ethanol, and 2.5 g of ethyl acetate to the mixing bottle; after shaking and mixing evenly, place it on a ball mill, rotate at 180 r / min, and mix for 48 h;

[0125] Conventional treatment of nickel foam: degrease with acetone, wash with water, soak in 3M hydrochloric acid and wash with water;

[0126] Filter the mixed liquid in the mixing bottle and pour it out, soak the nickel foam in it for 3 min and then take it out, and dry it at 50 °C for 30 min;

[0127] The soaked nickel foam is heated to 900 °C in a tube furnace and sintered for 2 h; the atmosphere during sintering is a mixed gas of N 2- 5% H2. The heating procedure is as follows: heat at a heating rate of 1.1 °C / min to 100 °C, then hold for 100 min; then heat at a heating rate of 0.41 °C / min to 200 °C and hold for 360 min; then heat at a heating rate of 0.40 °C / min to 300 °C (corresponding to heating to 300 °C within 270 minutes); then heat at a heating rate of 0.53 °C / min to 600 °C (corresponding to heating to 600 °C within 570 minutes), hold at this temperature for 630 min; then heat at a heating rate of 0.43 °C / min to 900 °C (corresponding to heating to 900 °C within 690 minutes), hold at this temperature for 810 min; finally, cool to room temperature in the furnace to obtain an integrated nickel foam high-entropy alloy, abbreviated as FeCoNiCrMn-NF.

[0128] Example 3

[0129] This example provides a preparation method of a foam Ni-high entropy alloy catalyst (FeCoNiCrMn-NF), which is different from Example 1 in that: the mixed liquid in the mixing bottle is filtered and poured out, the nickel foam is soaked in it for 10 min and then taken out, and dried at 50 °C for 30 min. Other preparation methods are the same as those in Example 1.

[0130] Comparative Example 1

[0131] Treat the nickel foam by a conventional method, that is, degrease with acetone, wash with water, and soak and wash with 3M hydrochloric acid.

[0132] Using the treated nickel foam as the working electrode, measure its OER overpotential in a 1 mol / L KOH alkaline solution under a three-electrode system.

[0133] Comparative Example 2

[0134] This example provides a preparation method of a foam Ni-high entropy alloy catalyst (FeCoNiCrMn-NF), which is different from Example 1 in that: 48 g of high-entropy alloy metal powder (particle size < 20 μm) with a molar ratio of Fe:Co:Ni:Cr:Mn = 1:1:1:1:1 and 8 g of Ni metal powder (particle size < 20 μm) are taken and added to the mixed solution; other preparation methods are the same as those in Example 1. That is, in this example, the mass ratio of Ni powder to high-entropy alloy metal powder is 1:6.

[0135] Comparative Example 3

[0136] This example provides a method for preparing a foam Ni-high entropy alloy catalyst (FeCoNiCrMn-NF), which is different from Example 1 in that: 40 g of high entropy alloy metal powder (particle size < 20 μm) is taken and added to a mixed solution; other preparation methods are the same as those in Example 1. That is, compared with Example 1, Ni metal powder is not added in this example.

[0137] Since Ni powder is not added in this example, uniform mixing of the high entropy alloy metal powder cannot be achieved during the mixing process, resulting in an uneven catalyst, and finally a foam Ni-high entropy alloy catalyst (FeCoNiCrMn-NF) is not prepared.

[0138] Structure and performance testing

[0139] Scanning electron microscopy was used to observe the microstructure of the foam nickel high entropy alloy prepared in Examples 1-2 and Comparative Example 2. Figure 1-2 The SEM images of the foam nickel high entropy alloy prepared in Examples 1-2 are respectively shown. Figure 5 The SEM image of the foam nickel high entropy alloy prepared in Comparative Example 2 is shown.

[0140] As can be seen from Figure 1-2 and 5, in the foam nickel high entropy alloy prepared in Examples 1-2, the foam nickel skeleton is completely covered by the loaded high entropy alloy. In Comparative Example 2, due to the relatively small Ni content used during ball milling mixing (Ni powder: high entropy alloy metal powder = 1:6), the prepared foam nickel high entropy alloy is uneven.

[0141] Taking the foam nickel high entropy alloy prepared in each example and comparative example as the working electrode, the Hg-HgO reference electrode as the reference electrode, and the platinum electrode as the counter electrode, the performance of the foam nickel high entropy alloy was tested by linear sweep voltammetry (LSV) in 1 mol / L KOH alkaline solution. Figure 3 The LSV diagrams of the foam nickel high entropy alloy prepared in Examples 1-2 and the foam nickel in Comparative Example 1 are shown. Figure 4 The LSV diagram of the foam nickel high entropy alloy prepared in Example 3 is shown.

[0142] As can be seen from Figure 3 it can be seen that the overpotential of the foam nickel high entropy alloy prepared in Example 1 is only 248 mV at a current density of 10 mA / cm 2 ². The overpotential of the foam nickel high entropy alloy prepared in Example 2 is only 238 mV at a current density of 10 mA / cm 2 ². The overpotential of the foam nickel in Comparative Example 1 is 338 mV at a current density of 10 mA / cm 2 ².

[0143] As can be seen fromFigure 4 It can be seen that the overpotential of the nickel foam high-entropy alloy prepared in Example 3 is 256 mV at a current density of 10 mA / cm 2 ².

Claims

1. A foam Ni-high entropy alloy catalyst, characterized in that, The foam Ni-high entropy alloy catalyst includes foam Ni, high entropy alloy, and metallic Ni; wherein, the high entropy alloy and metallic Ni are loaded on the surface of the foam Ni, and the foam Ni-high entropy alloy catalyst integrates the foam Ni and the high entropy alloy through the metallic Ni.

2. The preparation method of the foam Ni-high entropy alloy catalyst according to claim 1, characterized in that, The mass fraction of the metallic Ni loaded on the surface of the foam Ni is 20-40%.

3. The preparation method of the foam Ni-high entropy alloy catalyst according to claim 1, characterized in that, The high entropy alloy includes FeCoNiCrM, where M includes at least one of Mn and Mo; and / or, in the high entropy alloy, the molar ratio of Fe, Co, Cr, and M is 1:1:1:

1.

4. The preparation method of the foam Ni-high entropy alloy catalyst according to claim 1, characterized in that, In the high entropy alloy, the molar ratio of Fe, Co, Ni, Cr, and M is 3:3:8:3:

3.

5. A preparation method of the above-mentioned foam Ni-high entropy alloy catalyst, characterized in that, The preparation method includes the following steps: 1) Prepare wet mixture A; 2) Add the high entropy alloy metal powder and Ni metal powder into the wet mixture A and perform the first ball milling and mixing to obtain mixture A; 3) Add wet mixture B to mixture A, mix and then perform the second ball milling and mixing to obtain mixture B, and filter mixture B to retain the liquid part to obtain the impregnation solution; 4) Immerse the nickel foam in the impregnation solution obtained in step 3), then dry it, and sinter it to obtain the nickel foam-high entropy alloy catalyst.

6. The preparation method of the foam Ni-high entropy alloy catalyst according to claim 5, characterized in that, In step 1), the wet mixture A includes ethanol, ethyl acetate, and triethanolamine; in the wet mixture A, the mass ratio of ethanol, ethyl acetate, and triethanolamine is 4.8-5.2:2.8-3.2:

1.

7. The preparation method of the foam Ni-high entropy alloy catalyst according to claim 5, characterized in that, In step 2), the mass ratio of the high entropy alloy to the Ni metal powder is 3.8-4.2:1; and / or, in step 2), the particle size of the metal powder of the high entropy alloy < 20 μm; the particle size of the Ni metal powder < 20 μm.

8. The preparation method of the foam Ni-high entropy alloy catalyst according to claim 5, characterized in that, In step 2), the rotation speed of the first ball milling and mixing is 100-500 r / min, and the time is 20-50 h.

9. The preparation method of the foam Ni-high entropy alloy catalyst according to claim 5, characterized in that, In step 3), the wet mixture B includes PVB, polyethylene glycol, ethanol, and ethyl acetate; in the wet mixture B, the mass ratio of PVB, polyethylene glycol, ethanol, and ethyl acetate is 4.8-5.2:1:2.3-2.7:2.3-2.

7.

10. The preparation method of the foam Ni-high entropy alloy catalyst according to claim 5, characterized in that, In step 3), the rotation speed of the second ball milling and mixing is 100-500 r / min, and the time is 20-50 h.

11. The preparation method of the foam Ni-high entropy alloy catalyst according to claim 5, characterized in that, In step 4), the nickel foam is pretreated before immersion, and the pretreatment includes degreasing with acetone, water washing, and soaking and washing with 3M hydrochloric acid.

12. The preparation method of the foam Ni-high entropy alloy catalyst according to claim 5, characterized in that, In step 4), the soaking time of the nickel foam in the impregnation solution is 1-10 min.

13. The preparation method of the foam Ni-high entropy alloy catalyst according to claim 5, characterized in that, In step 4), the sintering temperature is 880-1100 °C, and the time is 1-5 h.

14. The preparation method of the foam Ni-high entropy alloy catalyst according to claim 5, characterized in that, In step 4), the sintering is carried out in a nitrogen-hydrogen mixed gas.

15. The preparation method of the foam Ni-high entropy alloy catalyst according to claim 5, characterized in that, In step 4), the sintering adopts a multi-stage heating mode.

16. The preparation method of the foam Ni-high entropy alloy catalyst according to claim 15, wherein, In step 4), the multi-stage heating mode of the sintering includes: the first-stage heating, the second-stage heating, the third-stage heating, the fourth-stage heating, and the fifth-stage heating.

17. The preparation method of the foam Ni-high entropy alloy catalyst according to claim 16, wherein, In step 4), during the sintering, the heating rate of the first-stage heating is greater than those of the second-stage heating, the third-stage heating, the fourth-stage heating, and the fifth-stage heating; the heating rates of the second-stage heating and the third-stage heating may be the same or different; the heating rates of the fourth-stage heating and the fifth-stage heating may be the same or different; the heating rates of the fourth-stage heating and the fifth-stage heating are greater than those of the second-stage heating and the third-stage heating.

18. The preparation method of the foam Ni-high entropy alloy catalyst according to claim 16 or 17, characterized in that, In step 4), the first-stage heating is carried out at a heating rate of 0.9 - 1.3 °C / min to 90 - 110 °C, and then held for 80 - 120 min; the second-stage heating is carried out at a heating rate of 0.3 - 0.5 °C / min to 180 - 220 °C and held for 300 - 400 min; the third-stage heating is carried out at a heating rate of 0.3 - 0.5 °C / min to 280 - 320 °C; the fourth-stage heating is carried out at a heating rate of 0.45 - 0.7 °C / min to 580 - 620 °C and held for 600 - 700 min; the fifth-stage heating is carried out at a heating rate of 0.45 - 0.7 °C / min to 880 - 1100 °C and held for 750 - 900 min.

19. Application of a foam Ni-high entropy alloy catalyst as described in any one of claims 1 - 4 as an oxygen evolution reaction catalyst or an oxygen evolution reaction electrode in the field of electrolytic water hydrogen production.

20. Use of the foam Ni-high entropy alloy catalyst according to claim 19 as an oxygen evolution reaction catalyst or an oxygen evolution reaction electrode in the field of electrolytic water hydrogen production, characterized in that, The as-prepared Ni-HEA foam catalyst can reduce the overpotential of oxygen evolution reaction to 238 mV at a current density of 10 mA cm -2 in 1 mol / L KOH alkaline solution.

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