A heusler alloy fiber oer catalyst, and a preparation method and application thereof

Abstract

A Heusler alloy fiber OER catalyst and a preparation method and application thereof.The present application belongs to the field of OER catalysts.The present application is directed to the technical problems of low catalytic efficiency, high preparation cost and difficulty in recycling of the existing oxygen evolution reaction catalysts. The present application innovatively selects a nickel-manganese-tin-cobalt alloy free of noble metals and toxic elements as the catalyst, the alloy block is prepared by an induction melting method, and then the Taylor wire drawing method is used to prepare the block into a micron fiber form, so as to increase the specific surface area, and then the micron fiber is sealed in a quartz tube together with manganese sheets and titanium wires and is subjected to heat treatment at a high temperature, so as to improve the composition uniformity of the micron fiber. The present application utilizes the green economic characteristics of the nickel-manganese-tin-cobalt, increases the specific surface area while maintaining the advantage of easy recycling, and thus makes the nickel-manganese-tin-cobalt fiber show a broad application prospect in the field of electrocatalytic water splitting.

Description

Technical Field

[0001] This invention belongs to the field of OER catalysts, specifically relating to a Heusler alloy fiber OER catalyst, its preparation method, and its application. Background Technology

[0002] Hydrogen energy is a clean, zero-carbon secondary energy source with high calorific value and abundant resources, making it the most promising alternative to fossil fuels. Electrocatalytic water splitting (ECWS) technology is currently the most common technology for producing hydrogen energy, but its inherent defects make it difficult to achieve the goal of using hydrogen energy as the primary energy source in the short term. (1) Low efficiency: ECWS is actually divided into two half-reactions: oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The OER reaction is a four-electron transfer process, which greatly limits the overall efficiency of ECWS and is a major rate-determining step in the ECWS process. (2) High cost and low stability of electrocatalysts: The most effective and commercially available electrolytic water catalysts currently contain a large amount of precious metals such as Ir, Ru, and Pt. Therefore, realizing an industrially feasible hydrogen production process based on non-precious metal efficient OER catalysts is an important topic for basic research and industrial application. Summary of the Invention

[0003] This invention addresses the technical problems of low catalytic efficiency, high preparation cost, and difficulty in recycling of existing oxygen evolution reaction (OER) catalysts. This invention provides a Heusler alloy fiber OER catalyst, its preparation method, and its application.

[0004] The technical solution of the present invention is as follows:

[0005] One objective of this invention is to provide a Heusler alloy fiber OER catalyst, wherein the Heusler alloy fiber OER catalyst is composed of Ni. w Mn x Sn y Co z The alloy has the following properties: 41≤w≤43, 42≤x≤44, 9≤y≤11, 4≤z≤6, and w+x+y+z=100. The fiber length is 10-30mm and the diameter is 250-450μm.

[0006] Preferably, the Heusler alloy fiber OER catalyst is composed of Ni. 42 Mn 43 Sn 10 Co5 alloy.

[0007] Preferably, the fiber length is 20 mm and the diameter is 350 μm.

[0008] The second objective of this invention is to provide a method for preparing a Heusler alloy fiber OER catalyst, the method comprising the following steps:

[0009] Ni w Mn x Sn y Co z The alloy ingot was sealed in a Pyrex glass tube and then drawn into fibers using the Taylor drawing method. After heat treatment, the glass was peeled off to obtain the Heusler alloy fiber OER catalyst.

[0010] Preferably, the Taylor wire drawing process parameters are as follows: the high-frequency induction heating temperature is 1073-1373K, the output power is 10-20KW, and when both the alloy ingot and the glass tube reach the molten state, a tungsten rod with a tip is used to draw out the nickel-manganese-tin-cobalt Heusler alloy fiber with glass coating from the bottom of the softened Pyrex glass tube at a speed of 1-2m / s.

[0011] More preferably, the high-frequency induction heating time is 1-3 minutes.

[0012] Preferably, the heat treatment is carried out in a sealed and vacuum-sealed quartz tube.

[0013] More preferably, the vacuum-sealed quartz tube also contains titanium wire and manganese sheet.

[0014] More preferably, the heat treatment parameters are: heating to 1173K at a rate of 10K / min, and then holding at that temperature for 8-10 hours.

[0015] The third objective of this invention is to provide an application of Heusler alloy fiber OER catalyst as a working electrode in OER.

[0016] The advantages of this invention compared to the prior art are:

[0017] This invention innovatively selects a nickel-manganese-tin-cobalt alloy free of precious metals and toxic elements as a catalyst. After preparing the alloy bulk using induction melting, the bulk is then processed into micron-fibers using the Taylor wire drawing method, thereby increasing its specific surface area. These fibers are then sealed together with manganese sheets and titanium wires in a quartz tube and heat-treated at high temperature to improve the uniformity of the micron-fiber composition. This invention utilizes the green and economical characteristics of nickel-manganese-tin-cobalt, increasing the specific surface area while maintaining the advantage of easy recycling, thus demonstrating broad application prospects for nickel-manganese-tin-cobalt fibers in electrocatalytic water splitting. Attached Figure Description

[0018] Figure 1The macroscopic and microscopic morphologies of the nickel-manganese-tin-cobalt Heusler alloy ingot and fiber obtained in the embodiments of the present invention are shown; (a) - macroscopic morphology of the ingot, (b) - macroscopic morphology of the fiber, (c) - microscopic morphology of the fiber, (dg) surface distribution diagram of nickel, manganese, tin and cobalt elements in the fiber;

[0019] Figure 2 The X-ray diffraction pattern of the nickel-manganese-tin-cobalt Heusler alloy fiber obtained in the embodiments of the present invention at room temperature;

[0020] Figure 3 The oxygen evolution catalytic curve of the nickel-manganese-tin-cobalt Heusler alloy fiber obtained in the embodiments of the present invention;

[0021] Figure 4 The slope of the Tafel catalyst for oxygen evolution catalysis obtained from the nickel-manganese-tin-cobalt Heusler alloy fiber in the embodiments of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0024] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used in the following embodiments, are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such a composition, step, method, article, or apparatus.

[0025] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range. In this specification and claims, range definitions may be combined and / or interchanged, unless otherwise stated, these ranges include all sub-ranges contained therein.

[0026] The indefinite articles “a” and “an” preceding an element or component of this invention do not impose any limitation on the quantity (i.e., number of times) of the element or component. Therefore, “an” or “a” should be interpreted as including one or at least one, and the singular form of an element or component also includes the plural form, unless the quantity clearly refers only to the singular form.

[0027] Example

[0028] (1) Preparation of alloy ingots:

[0029] First, clean the 99.98% high-purity nickel sheet in aqua regia (a mixture of concentrated hydrochloric acid and concentrated nitric acid in a volume ratio of 3:1) for 30 seconds, then transfer it to distilled water for ultrasonic cleaning for 3 minutes, and finally dry it with a hair dryer on cold air for later use.

[0030] Wash 99.95% high-purity manganese metal sheets in a 10% dilute nitric acid solution for 30 seconds, then transfer them to distilled water for ultrasonic cleaning for 3 minutes. After removing them, repeat the process of washing them in a 10% dilute nitric acid solution for 30 seconds, then transferring them to distilled water for ultrasonic cleaning for 3 minutes, then transferring them to anhydrous alcohol for ultrasonic cleaning for 3 minutes, and finally drying them with a hair dryer on cold air for later use.

[0031] The 99.90% high-purity tin block was cleaned in a 10% nitric acid solution for 2 minutes, then transferred to distilled water for ultrasonic cleaning for 3 minutes, and finally dried with a hair dryer on cold air for later use.

[0032] The 99.95% high-purity cobalt metal block was washed in a 30% dilute nitric acid solution for 2 minutes, then transferred to distilled water for ultrasonic cleaning for 3 minutes, and finally dried with a hair dryer in cold air for later use.

[0033] Then, press Ni 42 Mn 43 Sn 10The atomic ratio of Co5 was determined by weighing out nickel sheets, manganese sheets, tin blocks, and cobalt blocks, with a total mass of 35g. To compensate for elemental losses during atomization, high-purity manganese sheets, accounting for 3% of the total metal mass, were added. The raw materials were then placed in a crucible in the order of manganese, tin, nickel, and cobalt, and smelted using a high-frequency induction melting method under a vacuum of 10... -1 The alloy was melted at a power of 3 kW until completely melted. Argon gas was then introduced, and the power was increased to 3.68 kW and maintained for 3 minutes to ensure thorough and uniform mixing in the argon environment. The alloy was then cast, and the same ingot was melted three times. The resulting ingot was then cut into alloy cylindrical blocks with a diameter of 5 mm and a height of 6 mm using wire electrical discharge machining. These blocks were then ultrasonically cleaned in acetone solution for 5 minutes before use.

[0034] (2) Alloy fiber preparation:

[0035] First, the alloy cylindrical block is picked up with tweezers and placed into a sealed Pyrex glass (high borosilicate glass, softening temperature about 1100-1150K) tube that has been evacuated and backfilled with high-purity argon. Then, it is fixed onto a Taylor wire drawing device, so that the alloy cylindrical block is in a conical induction coil. It is heated continuously for 2 minutes at 1173K and an output power of 15KW. When both the alloy cylindrical block and the Pyrex glass tube reach the molten state, the nickel-manganese-tin-cobalt Heusler alloy fiber with glass coating is pulled out from the bottom of the softened Pyrex glass tube at a speed of 1.5m / s using a tungsten rod with a tip.

[0036] (3) Heat treatment:

[0037] First, glass-coated nickel-manganese-tin-cobalt Heusler alloy fibers are placed into a cleaned quartz tube. Then, high-purity titanium wire (as an oxygen remover) and manganese sheets (to prevent manganese volatilization) are added, and the sample is kept away from the manganese sheets and titanium wires to complete the pretreatment.

[0038] Then, the quartz tube was evacuated for 25 minutes to achieve a vacuum level of 10. -4 Below 0.02 MPa, backfill with 0.1 MPa of 99.999% high-purity argon gas, repeating the purging process twice. Finally, backfill with 0.02 MPa of 99.999% high-purity argon gas. Seal using an oxyacetylene flame.

[0039] Next, at room temperature, the vacuum-sealed quartz tube was placed in a high-temperature furnace and heated to 1173 K at a rate of 10 K / min, and held at that temperature for 8 hours. Afterward, the sample was removed from the high-temperature furnace and air-cooled to room temperature.

[0040] Finally, the heat-treated glass-coated nickel-manganese-tin-cobalt Heusler alloy fibers are crushed under a steel plate to obtain nickel-manganese-tin-cobalt Heusler alloy fibers.

[0041] Macroscopic morphology of alloy ingots as follows Figure 1 As shown in Figure a, the macroscopic and microscopic morphologies of the fiber after heat treatment are as follows: Figure 1 As shown in b and c, the alloy fibers have uniform diameter, relatively smooth surface, average length ~20 mm, and average diameter ~350 μm. Elemental distribution analysis of the alloy fibers yielded the following results: Figure 1 The elemental distribution diagram shown in (dg) indicates that the elements nickel, manganese, tin, and cobalt are relatively evenly distributed.

[0042] Figure 2 The image shows the X-ray diffraction pattern of nickel-manganese-tin-cobalt Heusler alloy fibers at room temperature. At room temperature, only peaks (200), (400), and (422) appear in the sample, indicating that only the L21 austenitic structure exists, suggesting that the martensitic phase transformation temperature of the sample is below room temperature.

[0043] Application example:

[0044] The application of the nickel-manganese-tin-cobalt Heusler alloy fiber prepared in the above embodiments of the present invention as a working electrode in OER is as follows:

[0045] A standard three-electrode system was connected to the CHI660E electrochemical workstation, and OER electrochemical tests were performed in 0.1M KOH electrolyte at room temperature. This three-electrode system consisted of a working electrode, a reference electrode, and a counter electrode, with the Hg / HgO electrode serving as the reference electrode and the carbon rod as the counter electrode.

[0046] For the preparation of the working electrode, a nickel-manganese-tin-cobalt Heusler alloy fiber prepared in the above embodiments of the present invention was placed in a platinum electrode clamp and clamped. The microfilament was then almost entirely immersed in the electrolyte (note that the platinum electrode clamp should not contact the electrolyte). Before the oxygen evolution test (OER), oxygen (O2) was introduced into the electrolyte to saturate it, and the electrolyte was continuously magnetically stirred at 300 rpm / min to prevent O2 bubbles from accumulating on the surface of the working electrode. Before collecting electrochemical data, the working electrode was activated by cycling 25 times at a scan rate of 100 mV / s within the range of 0.2-1.0 V vs Hg / HgO. In the test, the scan voltage for the linear sweep surface polarization curves (LSVs) was 0.2 to 1.0 V (vs Hg / HgO), and the scan rate was 5 mV / s. -1After the test, the microfilament was removed from the platinum electrode clamp, and its diameter was measured using a micrometer. The surface area of ​​the fiber was calculated using an approximate method for calculating the surface area of ​​a cylinder. Data was processed using data exported from the electrochemical workstation, along with the fiber's specific surface area, the pH of the electrolyte, and the standard potential of the reference electrode. All potentials were then converted to the reversible hydrogen electrode potential E according to the Nernst equation. RHE =E Hg / HgO +0.059*pH+0.098 where E RHE E is the reversible hydrogen electrode potential. Hg / HgO The experimental electrode potential was measured using Hg / HgO as the reference electrode.

[0047] The oxygen evolution catalytic curve is as follows: Figure 3 As shown in the figure, the overpotential is approximately 300 mV. This performance is close to that of commercially available iridium oxide (IrO2, 291 mV overpotential) and ruthenium oxide (RuO2, 292 mV overpotential), demonstrating excellent oxygen evolution catalytic performance.

[0048] In the oxygen evolution reaction (OER), a smaller Tafel slope indicates a faster increase in current density, suggesting faster catalyst kinetics and better catalytic activity. The Tafel slope can be calculated from the OER catalytic curve of nickel-manganese-tin-cobalt Heusler alloy fibers. Figure 4 As shown, its Tafel slope is 105 mV / dec, demonstrating good oxygen evolution catalytic performance.

[0049] The above description is merely a preferred embodiment of the present invention. These specific embodiments are different implementations based on the overall concept of the present invention, and the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A Heusler alloy fiber OER catalyst, characterized in that, Its composition is Ni w Mn x Sn y Co z The alloy has the following properties: 41≤w≤43, 42≤x≤44, 9≤y≤11, 4≤z≤6, and w+x+y+z=100. The fiber length is 10-30mm and the diameter is 250-450μm.

2. The OER catalyst according to claim 1, characterized in that, The component is Ni 42 Mn 43 Sn 10 Co5 alloy.

3. The OER catalyst according to claim 1, characterized in that, The fiber is 20mm long and 350μm in diameter.

4. The method for preparing the Heusler alloy fiber OER catalyst according to any one of claims 1-3, characterized in that, Follow these steps: Ni w Mn x Sn y Co z The alloy ingot was sealed in a Pyrex glass tube and then drawn into fibers using the Taylor drawing method. After heat treatment, the glass was peeled off to obtain the Heusler alloy fiber OER catalyst.

5. The method according to claim 4, characterized in that, Taylor wire drawing process parameters: high frequency induction heating temperature is 1073-1373K, output power is 10-20KW. When both the alloy ingot and the glass tube reach the molten state, a tungsten rod with a tip is used to draw out the nickel-manganese-tin-cobalt Heusler alloy fiber with glass coating from the bottom of the softened Pyrex glass tube at a speed of 1-2m / s.

6. The method according to claim 5, characterized in that, The high-frequency induction heating time is 1-3 minutes.

7. The method according to claim 4, characterized in that, The heat treatment was carried out in a sealed and vacuum-sealed quartz tube.

8. The method according to claim 7, characterized in that, The vacuum-sealed quartz tube also contains titanium wire and manganese sheet.

9. The method according to claim 7, characterized in that, Heat treatment parameters: Heat to 1173K at a rate of 10K / min, and then hold for 8-10 hours.

10. The application of the Heusler alloy fiber OER catalyst according to any one of claims 1-3 as a working electrode in OER.

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