Honeycomb porous C14 type Laves high-entropy alloy catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the field of application of high-entropy alloy in catalytic materials, and particularly relates to a honeycomb porous C14 type Laves phase high-entropy alloy catalyst as well as a preparation method and application thereof. The chemical formula of the alloy catalyst is Ti < 0.8 > Zr < 0.2 > V < 0.2 > Mn < x > Cr < 1.8-x >, x is equal to 0.8-1.0, a high-entropy alloy with a C14 Laves phase structure is obtained through electric arc melting, the high-entropy alloy and Mg powder are mechanically mixed and pressed into a sheet after being ground, and a composite material of Mg-Ti < 0.8 > Zr < 0.2 > V < 0.2 > Mn < x > Cr < 1.8-x > is obtained through sintering; and crushing the composite material, carrying out ball milling and refining, and etching in a citric acid solution to remove an Mg phase, thereby obtaining the C14 Laves phase high-entropy alloy catalyst with a honeycomb porous structure. The high-entropy alloy catalyst disclosed by the invention is uniform in component and large in specific surface area, has the advantages of porous morphology and C14 Laves phase structure, and shows excellent electrocatalytic oxygen evolution performance and excellent stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalytic materials, and in particular relates to a honeycomb porous C14 type Laves phase high entropy alloy catalyst and a preparation method thereof, as well as application of the catalyst in water deoxygenation reaction. Background Art

[0002] An electrolytic cell for water electrolysis typically consists of an external power source, a proton exchange membrane, an electrolyte, a cathode, and an anode. The oxygen evolution reaction (OER) occurs at the anode to produce oxygen, while the hydrogen evolution reaction (HER) occurs at the cathode to produce hydrogen. The OER, due to its complex four-electron transfer process, has a high kinetic barrier and slow reaction rate, making it a key factor limiting the improvement of overall water splitting efficiency. Therefore, efficient catalysts that can accelerate the OER process have become a research focus. Ruthenium dioxide (RuO2) and iridium dioxide (IrO2) are currently widely used catalyst materials in the field of OER catalysis due to their excellent catalytic performance. However, since both ruthenium and iridium are precious metals, their high price and scarce reserves have greatly restricted the large-scale application of related technologies. Therefore, the development of low-cost, high-availability, and highly efficient non-precious metal catalysts has become a key breakthrough in the industry. High-entropy alloys (HEAs) are attracting increasing attention due to their unique effects and high stability. They are expected to break away from the dependence on precious metal catalysts and provide new insights into the research of efficient OER catalysts.

[0003] High-entropy alloys (HEAs) are composed of five or more elements, and their unique "four major effects" are high entropy, hysteretic diffusion, lattice distortion, and cocktail effects. The high entropy effect can cause the system to tend to form an ideal single-phase solid solution, enhancing the thermodynamic stability of the catalyst; the hysteresis effect can make it difficult for atoms to diffuse across the lattice, thereby enhancing the catalyst's dynamic stability; the differences in atomic radius among the numerous elements can cause severe lattice distortion, which can enhance the strength of the HEAs and, to a certain extent, improve structural stability and prevent structural collapse during catalysis; and the "cocktail" effect, resulting from the random combination of elements in the alloy, can enhance the adsorption of HEAs by altering the electron distribution structure of the atoms within the elements, thereby affecting the chemical activity and selectivity of electrocatalytic reactions. By combining the inherent effects of HEAs with the selection of elements and the regulation of their proportions, it is hoped that HEAs with high catalytic performance can be developed, making them potential alternatives to precious metals in electrocatalytic materials.

[0004] In recent years, high-entropy alloys (HCAs) have continued to attract increasing attention in the field of electrocatalysis due to their excellent catalytic efficiency and durability. Currently reported high-entropy electrocatalyst phase structures are mainly BCC and FCC structures. However, these phase-structured catalysts are prone to intergranular corrosion in strongly oxidizing environments, leading to structural failure. In addition, most of these alloys are solid solution alloy structures, with atoms randomly occupying lattice sites, making it difficult to precisely control the active sites. In contrast, the HCP structure exhibits remarkable structural stability due to its hexagonal symmetry and low grain boundary energy. The Laves phase (such as the C14 type) is a long-range ordered intermetallic compound with a regular atomic arrangement, and the active sites can be precisely designed. Therefore, high-entropy alloys that combine the characteristics of the HCP structure and the Laves phase are expected to become more promising electrocatalysts.

[0005] In addition, significant progress has been made in the study of introducing porous structures into high-entropy alloys to improve catalytic performance. For example, a porous AlCoCrFeNi high-entropy alloy with a BCC structure was obtained by dissolving the Al-containing phase through a selective dissolution method. The overpotential was 260 mV in a 1 mol / L KOH solution at a current density of 10 mA / cm², but stability tests showed that it could only be maintained for 10 h, and there was a problem of residual Al phase [Wang W, Lu YZ, Lu X. Rare Metals, 2023, 42(7): 2174-2181.]; In addition, some researchers prepared a sheet-like porous high-entropy alloy by removing NaCl from the FeCoNiMg / NaCl system. Compared with FeCoNiMg alloy nanoparticles, the overpotential was reduced from 287 mV to 220 mV at a current density of 10 mA / cm² [CN 115491712 A]. This shows that designing a high-entropy alloy catalyst with a porous structure may exhibit better catalytic performance.

[0006] In view of this, combining the Laves phase and porosity of the HCP structure, a porous C14-type Laves phase high entropy alloy for water desorption oxygen reaction was designed and prepared, which has important practical application value. Summary of the Invention

[0007] The purpose of the present invention is to overcome the problems existing in traditional technologies, and to design a honeycomb porous C14 type Laves high entropy alloy catalyst, and at the same time develop a corresponding preparation method, and apply the catalyst to the water deoxygenation reaction.

[0008] The present invention provides a honeycomb porous C14 type Laves phase high entropy alloy catalyst, which has a C14 type Laves single-phase structure. The alloy components are all non-precious metal elements. According to the atomic molar ratio, the chemical formula of the porous high entropy alloy catalyst is Ti 0.8 Zr0.2 V 0.2 Mn x Cr 1.8-x ,in x = 0.8 ~ 1.0, and the alloy surface is covered with honeycomb-like pore structures with a specific surface area of ​​36.91 m 2 / g.

[0009] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions: Another object of the present invention is to provide a method for preparing a honeycomb porous C14 type Laves high entropy alloy catalyst, the preparation steps being as follows: (1) Weigh titanium blocks, zirconium blocks, manganese sheets, chromium blocks, and vanadium blocks according to the molecular formula ratio of the alloy catalyst; (2) In an argon atmosphere, the above metal raw materials are placed in a crucible from bottom to top according to the melting point from low to high, and a vacuum arc furnace is used to heat the crucible at (0.3 ~ 1.0) × 10 -2 The alloy is completely melted and cooled to form an alloy ingot. The alloy ingot is turned over and repeatedly melted 3 to 4 times to obtain a master alloy ingot with uniform composition. (3) In a glove box, the obtained alloy ingot was mechanically crushed into 200-300 mesh alloy precursor powder using a stainless steel mortar; (4) Weigh the desired alloy precursor powder and Mg powder in a glove box at a molar ratio of 3:7, place them in a ball mill, and mix them evenly; (5) Weigh the mixed sample using an analytical balance in a glove box and press it into tablets with a diameter of 10-15 mm using a powder tablet press; (6) Place the pressed pellet in a stainless steel sealed container in a glove box and fill it with argon gas at a pressure of 0.2-0.4 MPa; then place it in a muffle furnace for sintering. After sintering, cool it to room temperature and take it out to obtain a composite sample of Mg and alloy; (7) In a glove box, the obtained composite sample was mechanically crushed into 200-300 mesh powder using a stainless steel mortar and pestle, and then loaded into a ball mill for ball milling; (8) The ball-milled composite sample is subjected to weak acid etching, washed repeatedly, and vacuum dried to obtain a high entropy alloy catalyst.

[0010] Furthermore, in step (1), the purity of the titanium block is ≥99.9%, the purity of the zirconium block is ≥99.7%, the purity of the chromium block is ≥99.9%, the purity of the vanadium block is ≥99.9%, and the purity of the manganese sheet is ≥99.5%.

[0011] Furthermore, in step (1), considering that titanium blocks and manganese flakes may burn out during the arc melting process, 2 wt.% of titanium blocks and 5 wt.% of manganese flakes are additionally added. Since these additional additions are small, they are already burned out in the high temperature environment of the arc furnace, thus ensuring the formation of the C14 phase and thus having no impact on the catalyst performance.

[0012] Furthermore, in step (4), the Mg used is 200 mesh powder with a purity of ≥99.5%.

[0013] Furthermore, in step (4), 10 wt.% of Mg powder is additionally added to compensate for the burnout of Mg powder during the subsequent sintering process.

[0014] Furthermore, in step (4), no ball milling beads are added to the ball mill, the rotation speed is 200 r / min, and the time is 2 h.

[0015] Furthermore, in step (6), the sintering process is performed at a temperature of 550 to 650°C for 12 to 48 hours. This temperature range is set based on the melting point of Mg, which is 650°C. The bonding between Mg and the alloy depends on solid-state diffusion. When the temperature is below 550°C, the diffusion is slow. When the temperature is above 650°C, Mg becomes liquid, resulting in a large amount of Mg volatilization. During the sintering process, an oxide film is formed, which hinders diffusion.

[0016] Furthermore, in step (7), the protective atmosphere is argon, the ball-to-material ratio is 10:1, the rotation speed is 400 r / min, and the time is 20 h.

[0017] Furthermore, in step (8), the concentration of the weak acid is 0.3 to 0.5 mol / L, the pH is 1.8 to 2.0, the etching time is 5 to 12 h, and the etching temperature is 20 to 30°C.

[0018] In this step, the weak acid acts as an etchant, ensuring that Mg is removed while also ensuring that the matrix alloy is not corroded. Low concentrations may result in incomplete corrosion, while high concentrations may cause the elements in the high entropy to be corroded.

[0019] Furthermore, the weak acid includes but is not limited to one of citric acid, acetic acid or formic acid.

[0020] Furthermore, in step (8), the washing conditions are: the cleaning medium is deionized water and anhydrous ethanol.

[0021] Another object of the present invention is to provide the use of the above-mentioned honeycomb porous C14 type Laves high entropy alloy catalyst in the water desorption oxygen reaction, wherein in a 1 mol / L KOH solution, the overpotential at a current density of 10 mA / cm² is 300-331 mV and the electrochemical stability is maintained for 80 hours.

[0022] The principle of the present invention is to prepare a high-entropy alloy precursor with a C14-type Laves phase by arc melting. Then, after sintering it with Mg to form a composite sample, a honeycomb porous structure is etched on the refined alloy surface through ball milling and chemical dealloying. The improved oxygen evolution performance of the C14-type Laves phase high-entropy alloy of the present invention in water electrolysis can be attributed to the following reasons: on the one hand, Ti and Zr with larger atomic radii are selected as the A-side elements, and Mn, Cr, and V with smaller radii are selected as the B-side elements. This size difference induces lattice distortion, optimizes the electronic structure, and thus enhances the catalytic activity of the alloy. At the same time, the A-side (Ti, Zr) ensures the stability of the alloy during the electrocatalytic process due to its corrosion resistance, while the B-side (Mn, Cr, V) provides abundant active sites, showing higher catalytic activity. On the other hand, the larger interlayer spacing of the C14-type Laves phase structure significantly reduces the desorption activation energy of O2 compared to C15 and C36 types. Furthermore, the homogeneous hexagonal close-packed structure (high coordination number, low symmetry) exposes more active sites, promoting the rapid adsorption and desorption of *OOH intermediates. Furthermore, the C14-type Laves phase maintains its structural integrity during both dealloying (in an acidic environment) and electrocatalysis (in an alkaline environment), ensuring the formation of a porous structure and long-term catalysis. Furthermore, ball milling and the honeycomb porous structure increase the specific surface area of ​​the alloy, creating more active sites and significantly improving the material's oxygen evolution performance in water electrolysis.

[0023] Compared with the prior art, the present invention has the following beneficial effects: 1. Compared with traditional BCC / FCC phase high entropy alloy catalysts, the honeycomb porous C14 type Laves high entropy alloy catalyst of the present invention innovatively introduces C14 type Laves phase structure high entropy alloy into the field of electrocatalysis, making the catalyst both active and stable, and broadening the application boundaries of electrocatalysts.

[0024] 2. The elements in the alloy catalyst of the present invention are all non-precious metal elements, which significantly reduces the cost of the alloy.

[0025] 3. The catalyst of the present invention uses high-entropy powder and Mg powder to press and sinter, achieving sintering under low-temperature conditions. This not only effectively reduces the loss of the volatile element Mn, but also significantly improves the removal efficiency of Mg during the dealloying process. Moreover, using Mg as the dealloying element can well form a honeycomb porous structure on the alloy surface, and Mg can be completely removed under weak acid conditions, thereby ensuring the stability of the matrix alloy phase structure.

[0026] 4. The specific surface area of ​​the catalyst of the present invention reaches 36.91 m 2 / g, with the advantages of simple pore-forming process and environmental friendliness, in alkaline environment, 10 mA / cm -2 The required overpotential at the current density is only 300-331mV, and it shows excellent stability within 80 hours, effectively reducing energy costs and showing great potential value and development prospects in industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 As-cast Ti 0.8 Zr 0.2 V 0.2 Mn x Cr 1.8-x Alloy, Mg-Ti 0.8 Zr 0.2 V 0.2 Mn x Cr 1.8-x Composite samples and Ti dealloyed after ball milling 0.8 Zr 0.2 V 0.2 Mn x Cr 1.8-x ( x = 0.8, 0.9, 1.0) high entropy alloy samples.

[0028] Figure 2 Ti de-alloyed before and after ball milling 0.8 Zr 0.2 V 0.2 Mn 0.8 Scanning electron microscope image of Cr high entropy alloy.

[0029] Figure 3 Ti de-alloyed before and after ball milling 0.8 Zr 0.2 V 0.2 Mn 0.9 Cr 0.9 Scanning electron microscope image of a high-entropy alloy.

[0030] Figure 4 Ti de-alloyed before and after ball milling0.8 Zr 0.2 V 0.2 MnCr 0.8 Scanning electron microscope image of a high-entropy alloy.

[0031] Figure 5 Ti is dealloyed after ball milling 0.8 Zr 0.2 V 0.2 MnCr 0.8 Figure 2 shows nitrogen adsorption and desorption of high entropy alloys.

[0032] Figure 6 Ti is dealloyed after ball milling 0.8 Zr 0.2 V 0.2 Mn x Cr 1.8-x ( x = 0.8, 0.9, 1.0) linear sweep voltammograms of oxygen evolution reaction of high entropy alloys in 1 mol / L KOH electrolyte.

[0033] Figure 7 Ti prepared at sintering temperatures of 550℃, 600℃, and 650℃ 0.8 Zr 0.2 V 0.2 MnCr 0.8 Linear sweep voltammogram of the oxygen evolution reaction of a high-entropy alloy in 1 mol / L KOH electrolyte.

[0034] Figure 8 Ti prepared when the weak acid concentrations were 0.3 mol / L, 0.4 mol / L, and 0.5 mol / L 0.8 Zr 0.2 V 0.2 MnCr 0.8 Linear sweep voltammogram of the oxygen evolution reaction of a high-entropy alloy in 1 mol / L KOH electrolyte.

[0035] Figure 9 Ti is dealloyed after ball milling 0.8 Zr 0.2 V 0.2 MnCr 0.8 High entropy alloy in 1 mol / L KOH electrolyte, 10mV / cm 2 Stability diagram at different current densities. DETAILED DESCRIPTION

[0036] The technical solution of the present invention will be further described below in conjunction with specific embodiments. The following embodiments are merely exemplary illustrations of the present invention, and those skilled in the art may, without departing from the core concept of the present invention, implement equivalent variations of the technical solution through equivalent replacement or adaptive modification, and these improved solutions shall be deemed to be within the scope of protection of the present invention.

[0037] Example 1 Preparation of Ti 0.8 Zr 0.2 V 0.2 Mn 0.8 Cr high entropy alloy According to the chemical formula Ti 0.8 Zr 0.2 V 0.2 Mn 0.8 CrWeigh titanium block, zirconium block, manganese sheet, chromium block and vanadium block respectively, the total weight of raw materials is 15g; The weighed metal raw materials were added into the crucible in the order of melting point from low to high and from bottom to top. The alloy was smelted by arc melting in an argon atmosphere. The vacuum degree in the furnace was 3×10 -3 Pa, when the current rises to 300 A, the alloy is completely melted, then the heating is stopped, the temperature is kept for 5 minutes, and then the alloy is cooled. The alloy ingot is turned over and the melting is repeated 4 times to obtain Ti with uniform composition. 0.8 Zr 0.2 V 0.2 Mn 0.8 Cr alloy ingot (see Figure 1 :Cast Ti 0.8 Zr 0.2 V 0.2 Mn 0.8 X-ray diffraction (XRD) test spectrum of Cr high entropy alloy); (3) In a glove box, the obtained alloy ingot was mechanically crushed into 200-mesh powder using a stainless steel mortar; (4) According to the molar ratio of 3:7, the crushed Ti was weighed using an analytical balance in a glove box. 0.8 Zr 0.2 V 0.2 Mn 0.8 5 g of Cr alloy powder and Mg powder (200 mesh) were placed in a ball mill without ball milling beads filled with argon and mixed on a ball mill at a speed of 200 r / min for 2 h.

[0038] (5) In a glove box, 3 g of the mixed sample was weighed using an analytical balance, placed in a tableting device, and pressed into tablets with a diameter of 13 mm using a powder tablet press; (6) In a glove box, the pressed tablets were wrapped with high-melting-point tantalum sheets, placed in a sealed stainless steel container, and filled with argon at a pressure of 0.4 MPa. The filled stainless steel container was placed in a muffle furnace for sintering at 600 °C for 24 h, and then taken out after cooling to room temperature to obtain Mg-Ti 0.8 Zr 0.2 V 0.2 Mn 0.8 Cr composite specimen (see Figure 1 :Mg-Ti 0.8 Zr 0.2 V 0.2 Mn 0.8 X-ray diffraction (XRD) test spectrum of Cr composite sample); (7) In a glove box, the composite sample was crushed and ground into 200-mesh alloy powder in a stainless steel mortar, and then placed in a ball mill filled with argon for ball milling. The ball milling time was 20 h, the ball-to-material ratio was 10:1, the rotation speed was 400 r / min, and the ball milling time was 5 min after every 30 min. (8) The ball-milled composite sample was etched in 0.4 mol / L citric acid solution for 4 h at room temperature. After etching, it was repeatedly washed with deionized water and anhydrous ethanol until the solution was neutral. After vacuum drying, honeycomb porous Ti was obtained. 0.8 Zr 0.2 V 0.2 Mn 0.8 Cr high entropy alloy catalyst (see Figure 1 :Ti dealloyed after ball milling 0.8 Zr 0.2 V 0.2 Mn 0.8 X-ray diffraction (XRD) test spectrum of Cr high entropy alloy).

[0039] Honeycomb porous Ti 0.8 Zr 0.2 V 0.2 Mn 0.8 The phase structure of Cr high entropy alloy is a single C14 type Laves phase (see Figure 2 :Ti dealloyed after ball milling 0.8 Zr 0.2 V 0.2 Mn 0.8 Scanning electron microscope image of Cr high entropy alloy), the electrocatalytic oxygen evolution performance test results at room temperature show that in 1 mol / L KOH solution, 10 mA / cm 2 At this current density, the overpotential reaches 331 mV (see Figure 6 :Ti dealloyed after ball milling 0.8 Zr 0.2 V 0.2 Mn0.8 Linear sweep voltammogram of oxygen evolution reaction of Cr high entropy alloy in 1 mol / L KOH electrolyte), which shows that the catalyst has excellent oxygen evolution performance.

[0040] Example 2 Preparation of Ti 0.8 Zr 0.2 V 0.2 Mn 0.9 Cr 0.9 High-entropy alloys According to the chemical formula Ti 0.8 Zr 0.2 V 0.2 Mn 0.9 Cr 0.9 Weigh titanium block, zirconium block, manganese sheet, chromium block and vanadium block respectively, with a total weight of 15 g; The weighed metal raw materials were added into the crucible in the order of melting point from low to high and from bottom to top. The alloy was smelted by arc melting in an argon atmosphere. The vacuum degree in the furnace was 3×10 -3 Pa, when the current rises to 300 A, the alloy is completely melted, then the heating is stopped, the temperature is kept for 5 minutes, and then the alloy is cooled. The alloy ingot is turned over and the melting is repeated 4 times to obtain Ti with uniform composition. 0.8 Zr 0.2 V 0.2 MnCr 0.8 Alloy ingot (see Figure 1 :Cast Ti 0.8 Zr 0.2 V 0.2 Mn 0.9 Cr 0.9 X-ray diffraction (XRD) test spectrum of high entropy alloy); (3) In a glove box, the obtained alloy ingot was mechanically crushed into 200-mesh powder using a stainless steel mortar; (4) According to the molar ratio of 3:7, the crushed Ti was weighed using an analytical balance in a glove box. 0.8 Zr 0.2 V 0.2 Mn 0.9 Cr 0.9 Alloy powder and Mg powder (200 mesh), totaling 5 g, were placed in a ball mill without ball milling beads filled with argon and mixed on a ball mill at a speed of 200 r / min for 2 h. (5) In a glove box, 3 g of the mixed sample was weighed using an analytical balance, placed in a tableting device, and pressed into tablets with a diameter of 13 mm using a powder tablet press; (6) In a glove box, the pressed tablets were wrapped with high-melting-point tantalum sheets, placed in a sealed stainless steel container, and filled with argon at a pressure of 0.4 MPa. The filled stainless steel container was placed in a muffle furnace for sintering at 600 °C for 24 h, and then taken out after cooling to room temperature to obtain Mg-Ti 0.8 Zr 0.2 V 0.2 MnCr 0.8 Composite specimens; (7) In a glove box, the composite sample was crushed and ground into 200-mesh alloy powder in a stainless steel mortar, and then placed in a ball mill filled with argon for ball milling. The ball milling time was 20 h, the ball-to-material ratio was 10:1, the rotation speed was 400 r / min, and the ball milling time was 5 min after every 30 min. (8) The ball-milled composite sample was etched in 0.4 mol / L citric acid solution for 4 h at room temperature. After etching, it was repeatedly washed with deionized water and anhydrous ethanol until the solution was neutral. After vacuum drying, honeycomb porous Ti was obtained. 0.8 Zr 0.2 V 0.2 Mn 0.9 Cr 0.9 High entropy alloy catalysts.

[0041] Honeycomb porous Ti 0.8 Zr 0.2 V 0.2 Mn 0.9 Cr 0.9 The phase structure of high entropy alloy is a single C14 type Laves phase (see Figure 3 :Ti dealloyed after ball milling 0.8 Zr 0.2 V 0.2 Mn 0.9 Cr 0.9 Scanning electron microscope image of high entropy alloy), the electrocatalytic oxygen evolution performance test results at room temperature show that in 1 mol / L KOH solution, 10 mA / cm 2 At this current density, the overpotential reaches 310 mV (see Figure 6 :Ti dealloyed after ball milling 0.8 Zr 0.2 V 0.2 Mn 0.9 Cr 0.9 Linear sweep voltammogram of oxygen evolution reaction of high entropy alloy in 1 mol / L KOH electrolyte), which shows that the catalyst has excellent oxygen evolution performance.

[0042] Example 3 Preparation of Ti 0.8 Zr 0.2 V0.2 MnCr 0.8 High-entropy alloys According to the chemical formula Ti 0.8 Zr 0.2 V 0.2 MnCr 0.8 Weigh titanium block, zirconium block, manganese sheet, chromium block and vanadium block respectively, with a total weight of 15 g; The weighed metal raw materials were added into the crucible in the order of melting point from low to high and from bottom to top. The alloy was smelted by arc melting in an argon atmosphere. The vacuum degree in the furnace was 3×10 -3 Pa, when the current rises to 300 A, the alloy is completely melted, then the heating is stopped, the temperature is kept for 5 minutes, and then the alloy is cooled. The alloy ingot is turned over and the melting is repeated 4 times to obtain Ti with uniform composition. 0.8 Zr 0.2 V 0.2 MnCr 0.8 Alloy ingot (see Figure 1 :Cast Ti 0.8 Zr 0.2 V 0.2 Mn 0.8 X-ray diffraction (XRD) test spectrum of Cr high entropy alloy); (3) In a glove box, the obtained alloy ingot was mechanically crushed into 200-mesh powder using a stainless steel mortar; (4) According to the molar ratio of 3:7, the crushed Ti was weighed using an analytical balance in a glove box. 0.8 Zr 0.2 V 0.2 MnCr 0.8 Alloy powder and Mg powder (200 mesh), totaling 5 g, were placed in a ball mill without ball milling beads filled with argon and mixed on a ball mill at a speed of 200 r / min for 2 h. (5) In a glove box, 3 g of the mixed sample was weighed using an analytical balance, placed in a tableting device, and pressed into tablets with a diameter of 13 mm using a powder tablet press; (6) In a glove box, the pressed tablets were wrapped with high-melting-point tantalum sheets, placed in a sealed stainless steel container, and filled with argon at a pressure of 0.4 MPa. The filled stainless steel container was placed in a muffle furnace for sintering at 600 °C for 24 h, and then taken out after cooling to room temperature to obtain Mg-Ti 0.8 Zr 0.2 V 0.2 MnCr 0.8 Composite specimens; (7) In a glove box, the composite sample was crushed and ground into 200-mesh alloy powder in a stainless steel mortar, and then placed in a ball mill filled with argon for ball milling. The ball milling time was 20 h, the ball-to-material ratio was 10:1, the rotation speed was 400 r / min, and the ball milling time was 5 min after every 30 min. (8) The ball-milled composite sample was etched in 0.4 mol / L citric acid solution for 4 h at room temperature. After etching, it was repeatedly washed with deionized water and anhydrous ethanol until the solution was neutral. After vacuum drying, honeycomb porous Ti was obtained. 0.8 Zr 0.2 V 0.2 MnCr 0.8 High entropy alloy catalysts.

[0043] Honeycomb porous Ti 0.8 Zr 0.2 V 0.2 MnCr 0.8 The phase structure of high entropy alloy is a single C14 type Laves phase (see Figure 4 :Ti dealloyed after ball milling 0.8 Zr 0.2 V 0.2 MnCr 0.8 Scanning electron microscope image of high entropy alloy). Its specific surface area reaches 36.91 m 2 / g (see Figure 5 :Ti dealloyed after ball milling 0.8 Zr 0.2 V 0.2 MnCr 0.8 Nitrogen adsorption and desorption of high entropy alloys (see attached figure). The results of the electrocatalytic oxygen evolution performance test at room temperature show that in 1 mol / L KOH solution, 10 mA / cm 2 At current densities of 300 mV, the overpotential is Figure 9 :Ti dealloyed after ball milling 0.8 Zr 0.2 V 0.2 MnCr 0.8 Linear sweep voltammogram of the oxygen evolution reaction of the high-entropy alloy in 1 mol / L KOH electrolyte), while maintaining electrochemical stability for 80 h, indicating that the catalyst has excellent oxygen evolution performance and stability.

[0044] Example 4-Example 5 Compared with Example 1, the sintering temperature in Example 4 is 550°C, and the sintering temperature in Example 5 is 650°C. The high entropy alloys prepared in Examples 1, 4 and 5 are subjected to water electrolysis and oxygen evolution reaction in 1 mol / L KOH electrolyte. The reaction temperature is 10 mA / cm 2Under current density, as the sintering temperature increases, the overpotential decreases continuously, but the catalytic performance of the alloy does not change significantly, indicating that the catalytic performance of the alloy still maintains a good catalytic effect within this sintering temperature.

[0045] Example 6-Example 7 Compared with Example 1, the weak acid concentration in Example 6 is 0.3 mol / L, and the weak acid concentration in Example 7 is 0.5 mol / L. The high entropy alloys prepared in Examples 1, 6, and 7 are subjected to electrolysis and oxygen evolution reaction in 1 mol / L KOH electrolyte, 10 mA / cm 2 Under current density, as the weak acid concentration increases, its overpotential continues to decrease, but the catalytic performance of the alloy does not change significantly, indicating that the catalytic performance of the alloy still maintains a good catalytic effect within this weak acid concentration.

[0046] It should be noted that the embodiments shown above are merely illustrative, and their contents do not cover all possible implementation details, nor do they limit the scope of application of the present invention. Based on the technical inspiration of this specification, those skilled in the art can make various adaptive adjustments. The detailed description of specific embodiments is intended to help those skilled in the art understand the technical principles and implementation plans of the present invention. The scope of protection of the present invention is ultimately determined by the claims and their equivalent technical solutions.

Claims

1. A honeycomb porous C14 type Laves phase high entropy alloy catalyst, characterized in that: According to the atomic molar ratio, the chemical formula of the porous high entropy alloy catalyst is Ti 0.8 Zr 0.2 V 0.2 Mn x Cr 1.8-x ,in x = 0.8 ~ 1.0, the alloy surface is covered with honeycomb-like pore structure, and the specific surface area is 36.91 m 2 / g.

2. The method for preparing the honeycomb porous C14 type Laves phase high entropy alloy catalyst according to claim 1, wherein: The preparation steps are as follows: (1) Weigh titanium blocks, zirconium blocks, manganese sheets, chromium blocks, and vanadium blocks according to the molecular formula ratio of the alloy catalyst; (2) In an argon atmosphere, the above metal raw materials are placed in a crucible from bottom to top according to the melting point from low to high, and a vacuum arc furnace is used to heat the crucible at (0.3 ~ 1.0) × 10 -2 The alloy is completely melted and cooled to form an alloy ingot. The alloy ingot is turned over and repeatedly melted 3 to 4 times to obtain a master alloy ingot with uniform composition. (3) In a glove box, the obtained alloy ingot was mechanically crushed into 200-300 mesh alloy precursor powder using a stainless steel mortar; (4) Weigh the desired alloy precursor powder and Mg powder in a glove box at a molar ratio of 3:7, place them in a ball mill, and mix them evenly; (5) Weigh the mixed sample using an analytical balance in a glove box and press it into tablets with a diameter of 10-15 mm using a powder tablet press; (6) Place the pressed pellet in a stainless steel sealed container in a glove box and fill it with argon gas at a pressure of 0.2-0.4 MPa; then place it in a muffle furnace for sintering. After sintering, cool it to room temperature and take it out to obtain a composite sample of Mg and alloy; (7) In a glove box, the obtained composite sample was mechanically crushed into 200-300 mesh powder using a stainless steel mortar and pestle, and then loaded into a ball mill for ball milling; (8) The ball-milled composite sample is subjected to weak acid etching, washed repeatedly, and vacuum dried to obtain a high entropy alloy catalyst.

3. The method for preparing the honeycomb porous C14 type Laves phase high entropy alloy catalyst according to claim 2, characterized in that: In the step (2), during the arc melting process, 2 wt.% of titanium blocks and 5 wt.% of manganese sheets are added.

4. The method for preparing the honeycomb porous C14 type Laves phase high entropy alloy catalyst according to claim 2, characterized in that: In the step (4), the mixing conditions are: argon environment, no ball milling beads, rotation speed of 200 r / min, and time of 2 h.

5. The method for preparing the honeycomb porous C14 type Laves phase high entropy alloy catalyst according to claim 2, characterized in that: In step (6), the sintering temperature of the sintering process is 550 ~ 650 ° C, and the sintering time is 12 ~ 48 hours.

6. The method for preparing the honeycomb porous C14 type Laves phase high entropy alloy catalyst according to claim 2, characterized in that: In the step (7), the ball milling conditions are as follows: the protective atmosphere is argon, the ball-to-material ratio is 10:1, the rotation speed is 400 r / min, and the time is 20 h.

7. The method for preparing a honeycomb porous C14 type Laves phase high entropy alloy catalyst according to claim 2, characterized in that: In step (8), the concentration of the weak acid is 0.3 to 0.5 mol / L, the pH is 1.8 to 2.0, the etching time is 5 to 12 hours, and the etching temperature is 20 to 30°C.

8. The method for preparing the honeycomb porous C14 type Laves phase high entropy alloy catalyst according to claim 7, characterized in that: The weak acid includes but is not limited to one of citric acid, acetic acid or formic acid.

9. The method for preparing a honeycomb porous C14 type Laves phase high entropy alloy catalyst according to claim 2, characterized in that: In the step (8), the washing conditions are: the cleaning medium is deionized water and anhydrous ethanol.

10. Use of the honeycomb high-entropy alloy catalyst having a C14 Laves phase as claimed in claim 1 in a water desorption oxygen reaction, wherein in a 1 mol / L KOH solution, the overpotential at a current density of 10 mA / cm² is 300-331 mV, and the electrochemical stability is maintained for 80 hours.

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