Carbon-coated high-entropy alloy composite material as well as preparation method and application thereof

Abstract

The invention belongs to the field of application of high-entropy alloy in catalysis and hydrogen storage materials, and particularly relates to a carbon-coated high-entropy alloy composite material and a preparation method and application thereof.The molecular formula of the carbon-coated high-entropy alloy composite material is Ti < 0.5 > Zr < 0.5 > V < 0.2 > Mn < 0.2 > Cr < 0.4 > Fe < x > Ni < 1.2-x (at) C, x is equal to 0.2-1.0, and the specific surface area is 14.9064 m < 2 > / g. According to the composite material, precursor alloy obtained after electric arc melting is subjected to ball milling and refining into high-entropy powder, and the high-entropy powder is obtained. And then glucose is used as a carbon source, hydrothermal carbonization is carried out in a reaction kettle, calcination is carried out in an argon atmosphere, and the carbon-coated high-entropy alloy composite material can be obtained. According to the preparation method, a multi-element synergistic effect and Fe / Ni proportion regulation are combined with a carbon coating layer with a unique morphology to construct a multifunctional system integrating efficient electro-catalysis oxygen evolution and rapid hydrogen storage, so that the problems of element segregation and dissolution of an electro-catalysis material in a long-time reaction process are effectively inhibited while the alloy intrinsic performance of the alloy material is maintained, and the service life of the electro-catalysis material is prolonged. And meanwhile, the conductivity of the material is improved, the diffusion energy barrier of hydrogen in the Laves phase is reduced through the carbon defect on the surface layer, and the hydrogen storage dynamic performance can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalysis and hydrogen storage materials, and particularly relates to a carbon-coated high-entropy alloy composite material and a preparation method thereof, as well as the application of the alloy composite material with dual functions of oxygen evolution and hydrogen storage at room temperature. Background Art

[0002] In the field of hydrogen energy development, water electrolysis involves the decomposition of water (H2O) using electrical energy. The oxygen evolution reaction (OER) at the anode generates oxygen (O2), and the hydrogen evolution reaction (HER) at the cathode generates hydrogen (H2). To improve hydrogen production efficiency, high-efficiency catalysts are needed to lower the energy barrier of water decomposition. However, currently mainstream platinum-based electrocatalysts face challenges such as high cost, limited reserves, and insufficient long-term stability. Therefore, there is an urgent need to develop high-performance and cost-effective non-precious metal catalyst alternatives to break away from reliance on precious metal catalysts. Currently, three major hydrogen storage methods exist: high-pressure gas, low-temperature liquid, and solid-state. Solid-state storage holds the most promise due to its high capacity, safety, low cost, and ease of transportation. However, current mainstream hydrogen storage materials (such as AB5-type rare earth alloys and Mg-based hydrides) often suffer from insufficient hydrogen storage capacity, poor cycling stability, or excessive cost, necessitating the development of new, high-performance hydrogen storage material systems. In view of the above-mentioned problems of hydrogen preparation and storage, the development of materials with electrocatalytic and hydrogen storage applications has great application prospects, and the emergence of high-entropy alloys seems to provide a solution to this problem.

[0003] High-entropy alloys (HEAs), a new type of alloy composed of five or more elements, demonstrate significant application potential in electrocatalysis, hydrogen storage, and other fields due to their unique "four major effects." In electrocatalysis, the "high-entropy effect" effectively reduces the free energy of the system and improves catalyst stability. The "lattice distortion effect," derived from differences in atomic size, promotes the formation of abundant defects and strain sites on the alloy surface, providing a high density of active centers for catalytic reactions. The "slow diffusion effect" suppresses atomic migration, preventing compositional segregation caused by long-term reactions and extending catalyst life. The "cocktail effect" optimizes the adsorption / desorption behavior of reaction intermediates through the coordinated regulation of the electronic structures of multiple elements. In hydrogen storage, the "high-entropy effect" favors the formation of a single solid solution phase. The "lattice distortion effect" creates more interstitial sites, providing efficient diffusion channels for hydrogen atoms. The "slow diffusion effect" suppresses phase transformation and pulverization during hydrogen absorption and desorption. The "cocktail effect" allows alloys to break through the performance bottlenecks of single elements and achieve excellent composite properties.

[0004] However, the high-entropy alloys currently under development still face many bottlenecks, which restrict their practical applications in the fields of electrocatalysis and hydrogen storage. In the field of electrocatalysis, although the high surface activity of high-entropy alloys can improve catalytic efficiency, long-term exposure to air will lead to surface oxidation and inactivation; although powdered catalysts increase the density of active sites by increasing the specific surface area, they are prone to agglomeration and dissolution during long-term catalytic reactions, resulting in a significant attenuation of catalytic activity. In the field of hydrogen storage, the oxide layer on the surface of the alloy will hinder the diffusion of hydrogen atoms; at the same time, in the repeated absorption and desorption of hydrogen, element segregation or decomposition of the metastable phase is prone to occur, destroying the hydrogen storage active structure, thereby causing hydrogen storage capacity to decay. In addition, most high-entropy materials are only suitable for a single specific application scenario, and the research and development of high-entropy materials with cross-domain multifunctional applications is relatively scarce.

[0005] Based on the above analysis of the current status of high-entropy alloys, a high-entropy material with both electrocatalytic oxygen evolution and hydrogen storage properties was designed and prepared. While having excellent performance, it can also effectively inhibit the problems faced by high-entropy alloys during application, such as oxidation, agglomeration, segregation, and structural stability, and has important industrial application value. Summary of the Invention

[0006] The purpose of the present invention is to overcome the problems existing in traditional technologies, and to design a carbon-coated high-entropy alloy composite material with the dual functions of oxygen evolution and hydrogen storage, and at the same time develop a corresponding preparation method.

[0007] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions: The present invention provides a carbon-coated high entropy alloy composite material, the molecular formula of the alloy composite material is Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe x Ni 1.2-x @C, where x = 0.2~1.0, the specific surface area is 14.9064 m 2 / g.

[0008] The carbon-coated high-entropy alloy composite material of the present invention is designed based on thermodynamic calculations to design a precursor alloy with a C14-type Laves single-phase structure. By precisely controlling the Fe / Ni ratio in the alloy, the catalytic performance and hydrogen storage performance are balanced.

[0009] The present invention also provides a method for preparing the carbon-coated high-entropy alloy composite material, and the preparation steps are as follows: (1) Raw materials: according to Ti 0.5 Zr 0.5 V 0.2 Mn0.2 Cr 0.4 Fe x Ni 1.2-x @C alloy molecular formula titanium block, zirconium block, vanadium block, chromium block, iron block, nickel block and manganese sheet; (2) Alloy ingot smelting: In an argon atmosphere, the metal raw materials prepared in step (1) are placed in the crucible from bottom to top according to the melting point, and then -2 Arc vacuum melting is performed under a vacuum degree of Pa. After the alloy is completely melted and cooled, the formed alloy ingot is turned over and repeatedly melted 3 to 4 times to obtain a cast high entropy precursor alloy ingot. (3) In a glove box, crush the precursor alloy ingot in a stainless steel mortar and grind it into 200-300 mesh alloy powder; (4) In a glove box, weigh the precursor alloy powder and add it to a ball milling jar, and perform high-energy ball milling on a planetary ball mill; (5) Weigh the ball-milled precursor powder and glucose powder, add deionized water, stir thoroughly, and perform ultrasonic treatment; (6) Adding alkaline solution to the mixed solution to adjust the pH value; (7) The mixed solution is placed in a polytetrafluoroethylene reactor and hydrothermally carbonized in a drying oven. After the reaction is completed, the mixture is cooled to room temperature in the oven, taken out, centrifuged, washed, and vacuum dried. (8) The dried composite sample is placed in a tubular furnace and calcined under an argon atmosphere. After the calcination is completed, the sample is cooled to room temperature and then taken out to obtain a carbon-coated high-entropy alloy composite material; In the step (1), the purity of the titanium block is ≥99.9%, the purity of the zirconium block is ≥99.7%, the purity of the vanadium block is ≥99.9%, the purity of the chromium block is ≥99.9%, the purity of the iron block is ≥99.8%, the purity of the nickel block is ≥99.9%, and the purity of the manganese sheet is ≥99.5%.

[0010] In the step (1), considering that the titanium block and the manganese sheet may be burned during the arc melting process, 2 wt.% of the titanium block and 5 wt.% of the manganese sheet are additionally added.

[0011] In the step (4), the ball mill process has a ball-to-material ratio of 10-30:1 and a rotation speed of 350-450 r / min.

[0012] In the step (5), the mass ratio of the precursor alloy powder to the glucose powder is 2:1, the volume of the mixed solution is 30-40 ml, and the ultrasonic time is 30-60 min.

[0013] In the step (6), the alkaline solution is a sodium hydroxide solution, which is adjusted to a solution pH of 8-9.

[0014] In step (7), the hydrothermal reaction process is performed at a temperature of 160-180° C. for 5-12 hours.

[0015] In the step (8), the calcination process is performed at a temperature of 400-600° C. for 2-3 hours.

[0016] Another object of the present invention is to provide an application of the carbon-coated high-entropy alloy composite material in oxygen evolution. The composite material is drop-coated on carbon paper and used as a working electrode to perform electrolytic oxygen evolution in an alkaline electrolytic cell. In a 1 mol / L KOH solution, the overpotential at a current density of 10 mA / cm² is 267-283 mV, the charge transfer resistance is 0.989-1.476 Ω, and excellent electrochemical stability is exhibited within 98 hours.

[0017] Another object of the present invention is to provide an application of the carbon-coated high-entropy alloy composite material in hydrogen storage. Before the hydrogen storage function of the composite material is realized, after three cycles of hydrogen absorption and desorption at 300°C and 4MPa pressure, the hydrogen storage capacity reaches 1.17-1.21wt.%, and complete hydrogen absorption can be achieved within 100s and complete hydrogen desorption can be achieved within 150s at room temperature.

[0018] The principle of the present invention is: a high-entropy precursor alloy with a C14-type Laves phase (AB2 structure) is prepared by arc melting, which is then refined into a powdered high-entropy alloy using a ball milling process. Then, glucose is used as a carbon source, and hydrothermal carbonization and calcination are performed to construct a uniform carbon coating layer, ultimately obtaining a high-entropy composite material with both oxygen evolution and hydrogen storage functions.

[0019] The alloy composite material of the present invention has excellent performance in oxygen evolution by electrolysis of water due to the following reasons: (1) In this AB2-type Laves phase, the high-valent metal (Ti, Zr) introduced on the A side regulates the electron distribution of the transition metal (V, Mn, Cr, Fe, Ni) on the B side through electron transfer, thereby reducing the adsorption energy barrier of the reaction intermediate and enhancing the charge transfer efficiency of the active site. At the same time, the transition metal (V, Mn, Cr, Fe, Ni) elements on the B side synergistically optimize the adsorption energy of the oxygen intermediate and improve the intrinsic activity of the material; (2) The uniform carbon layer on the surface of the material gives it excellent electrical conductivity, effectively reduces the interfacial resistance of the material, and further accelerates the charge transfer rate; (3) At the same time, the electronic interaction between the high-entropy alloy surface and the carbon layer optimizes the electronic structure of the active site, accelerates the adsorption / desorption behavior of the intermediate product (*OOH), and thus reduces the overpotential of the oxygen evolution reaction; the carbon layer inhibits the agglomeration of powder particles through confinement, and at the same time reduces the dissolution of the highly active components (Fe, Ni) during the long-term reaction process, thereby extending the life of the material.

[0020] The excellent performance of the alloy composite material of the present invention in hydrogen storage is due to the following reasons: (1) Compared with the traditional BCC phase high entropy alloy, the tetrahedral and octahedral interstitial sites of the Laves phase high entropy alloy are densely distributed, providing more abundant chemical adsorption sites for hydrogen atoms, and the carbon layer reduces the diffusion energy barrier of hydrogen atoms in the lattice through interfacial action, thereby accelerating the rate of hydrogen absorption / desorption; (2) The confinement effect of the carbon layer inhibits the element segregation during the hydrogen absorption / desorption process and maintains the integrity of the Laves phase structure; (3) The strong interaction between the carbon layer and the metal interface weakens the lattice distortion caused by the hydrogen absorption and desorption process, maintaining the stability of the hydrogen storage active phase; (4) The defect sites in the carbon layer catalyze the dissociation of hydrogen molecules (H2) and the adsorption of hydrogen atoms (H), reducing the activation energy and improving the hydrogen absorption rate.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The alloy composite material of the present invention, through phase structure design, element selection and content control, combined with a hydrothermal carbon coating process, enables the composite material to integrate the multi-element synergistic effect of high-entropy alloys, the advantages of the C14-Laves phase structure, and the interface control effect of the carbon coating layer, innovatively constructing a dual-functional material system of efficient electrocatalytic oxygen evolution and rapid hydrogen storage, providing an efficient and low-cost solution for hydrogen production and storage.

[0022] During the preparation of the alloy material of the present invention, the alloy surface is subjected to carbon coating treatment, which not only significantly improves the oxygen evolution performance and hydrogen storage kinetics performance, but also effectively inhibits the oxidation, dissolution, segregation and agglomeration of the alloy material during the reaction process.

[0023] 2. The composite material of the present invention uses a low-temperature one-step hydrothermal process combined with a medium-temperature calcination process to achieve effective bonding between the carbon layer and the alloy interface, avoiding the complexity of traditional multi-step coating processes, significantly reducing energy consumption, and effectively avoiding the obstruction of the mass transfer process by an excessively thick carbon layer and the destruction of the C14-Laves phase structure by high temperature. At the same time, it inhibits the dissolution and loss of active elements such as Fe and Ni, ensuring the stability of the material structure and intrinsic properties. In addition, by regulating the Fe / Ni element ratio, it provides more flexible options for regulating the electronic structure and optimizing the performance of high-entropy alloys.

[0024] 3. After hydrothermal treatment and calcination, the high-entropy composite material of the present invention forms amorphous carbon and graphitic carbon on its surface. The amorphous carbon, through its high defectivity, increases the density of surface active sites, enhancing the kinetics of electrocatalytic and hydrogen storage reactions. The graphitic carbon accelerates electron transfer, significantly enhancing the alloy's conductivity while mitigating degradation phenomena such as agglomeration and element precipitation during operation, thereby improving durability.

[0025] 4. The high-entropy composite material of the present invention introduces a high density of defects on the alloy surface after ball milling. These defect sites act as stress release centers during the subsequent calcination process, causing the carbon layer to curl and bulge, forming a unique "pine cone-shaped" surface. This morphology increases the effective surface area of ​​the material and improves the mass transfer efficiency during oxygen evolution and hydrogen storage.

[0026] 5. All elements in the alloy material of the present invention are non-precious metal elements, and the process is simple, the synthesis path is short, and the process is highly controllable, showing great potential value and development prospects in the field of energy applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 As-cast Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe x Ni 1.2-x ( x = 0.2, 1.0) alloy samples, Ti after ball milling 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe x Ni 1.2-x ( x = 0.2, 1.0) high entropy powder samples and Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe x Ni 1. 2-x @C( x = 0.2, 1.0) X-ray diffraction (XRD) patterns of the composite samples; Figure 2 Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe x Ni 1.2-x @C( x = 0.2, 1.0) scanning electron micrograph of the composite sample; Figure 3 Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe x Ni 1.2-x @C(x = 0.2, 1.0) Raman spectrum of the composite sample; Figure 4 Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.2 Ni 1.2 @C Nitrogen adsorption and desorption diagram of composite sample; Figure 5 Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe x Ni 1.2-x @C( x = 0.2, 1.0) linear sweep voltammetry curves of oxygen evolution reaction of the composite sample in 1 mol / L KOH electrolyte; Figure 6 Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe x Ni 1.2-x @C( x =0.2, 1.0) AC impedance diagram of the composite sample in 1 mol / L KOH electrolyte; Figure 7 Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.2 Ni 1.0 @C Constant current electrochemical stability test curve of the composite sample in 1 mol / L KOH electrolyte.

[0028] Figure 8 Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe x Ni 1.2-x @C( x =0.2, 1.0) hydrogen absorption and desorption kinetics curves of the composite sample at 298K. DETAILED DESCRIPTION

[0029] 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.

[0030] Example 1: Preparation of Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 1.0 Ni 0.2 High entropy alloy composites (1) According to the chemical formula Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 1.0 Ni 0.2 , weigh titanium block, zirconium block, vanadium block, chromium block, manganese sheet, iron block and nickel block respectively, the total weight of raw materials is 15g; (2) 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 300A, the alloy is completely melted, then stop heating, keep warm for 5 minutes, then cool the alloy, turn the alloy ingot over, repeat the smelting 4 times, and you can get a uniform composition of Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 1.0 Ni 0.2 Precursor alloy ingot (see Figure 1 :Cast Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0. 4Fe 1.0 Ni 0.2 X-ray diffraction (XRD) test spectrum of high entropy alloy); (3) In a glove box, the obtained precursor alloy ingot was mechanically crushed into 200 mesh powder using a stainless steel mortar; (4) Weigh the crushed Ti using an analytical balance in a glove box. 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 1.0 Ni0.2 5 g of alloy powder was placed in a ball mill at a ball-to-material ratio of 10:1 and subjected to high-energy ball milling at a speed of 400 r / min for 5 h. (5) Weigh the ball-milled Ti according to a mass ratio of 2:1 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 1.0 Ni 0.2 Add 30 ml of deionized water to the alloy powder and glucose powder, stir to dissolve, and ultrasonically mix for 1 hour; (6) Gradually add 0.02 mol / L NaOH solution to the mixed solution after ultrasonication and test with a pH meter until the solution pH reaches 9.0; (7) Place the mixed solution in a 50 ml polytetrafluoroethylene hydrothermal reactor and perform hydrothermal carbonization in a drying oven for 12 h at a temperature of 180 °C. After the reaction is completed, cool the mixture to room temperature in the oven, remove the mixture, centrifuge, wash, and vacuum dry. (7) The dried sample was placed in a tube furnace and calcined in an argon atmosphere with a gas flow rate of 100 ml / min at a temperature of 600 ° C for 2 h. After cooling to room temperature, the sample was taken out to obtain Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 1.0 Ni 0.2 @C composite specimen (see Figure 1 :Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 1.0 Ni 0.2 @C X-ray diffraction (XRD) test spectrum of the composite sample).

[0031] Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 1.0 Ni 0.2 After the high entropy alloy is carbon coated, a uniform carbon layer is formed on the surface (see Figure 2 :Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 1.0 Ni0.2 @C scanning electron microscope image of the composite sample). At the same time, the D and G peaks in the Raman spectrum confirm the presence of graphitic carbon and a certain amount of defective carbon in the coating layer. This carbon layer structure can improve both conductivity and catalytic activity (see Figure 3 :Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 1.0 Ni 0.2 @C Raman spectrum of the composite sample). 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 this current density, the overpotential reaches 283 mV (see Figure 5 :Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 1.0 Ni 0.2 Linear sweep voltammetry curve of oxygen evolution reaction of @C composite sample in 1 mol / L KOH electrolyte).

[0032] In addition, the charge transfer resistance is only 1.476Ω (see Figure 6 :Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 1.0 Ni 0.2 @C composite sample in 1mol / L KOH electrolyte AC impedance diagram). The results of hydrogen absorption and desorption kinetics test show that Ti 0.5 Zr 0. 5V 0.2 Mn 0.2 Cr 0.4 Fe 1.0 Ni 0.2 The @C composite sample can absorb 1.17 wt.% of hydrogen at room temperature and release hydrogen almost completely at room temperature (see Figure 8 :Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 1.0 Ni 0.2 @C composite sample hydrogen absorption and desorption kinetics curve at 298K), which shows that the composite material has excellent oxygen evolution and hydrogen storage properties.

[0033] Example 2: Preparation of Ti0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.6 Ni 0.6 High entropy alloy composites (1) According to the chemical formula Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.6 Ni 0.6 Weigh titanium, zirconium, vanadium, chromium, manganese, iron, and nickel blocks, respectively, with a total weight of 15 g. (2) 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 300A, the alloy is completely melted, then stop heating, keep warm for 5 minutes, then cool the alloy, turn the alloy ingot over, repeat the smelting 4 times, and you can get a uniform composition of Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.6 Ni 0.6 Precursor alloy ingot (see Figure 1 :Cast Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0. 4Fe 0.6 Ni 0.6 X-ray diffraction (XRD) test spectrum of high entropy alloy); (3) In a glove box, the obtained precursor alloy ingot was mechanically crushed into 200 mesh powder using a stainless steel mortar; (4) Weigh the crushed Ti using an analytical balance in a glove box. 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.6 Ni 0.6 5 g of alloy powder was placed in a ball mill at a ball-to-material ratio of 10:1 and subjected to high-energy ball milling at a speed of 400 r / min for 5 h. (5) Weigh the ball-milled Ti according to a mass ratio of 2:1 0.5 Zr 0.5 V 0.2 Mn0.2 Cr 0.4 Fe 0.6 Ni 0.6 Add 30 ml of deionized water to the alloy powder and glucose powder, stir to dissolve, and ultrasonically mix for 1 hour; (6) Gradually add 0.02 mol / L NaOH solution to the mixed solution after ultrasonication and test with a pH meter until the solution pH reaches 9.0; (7) Place the mixed solution in a 50 ml polytetrafluoroethylene hydrothermal reactor and perform hydrothermal carbonization in a drying oven for 12 h at a temperature of 180 °C. After the reaction is completed, cool the mixture to room temperature in the oven, remove the mixture, centrifuge, wash, and vacuum dry. (8) The dried sample was placed in a tube furnace and calcined in an argon atmosphere with a gas flow rate of 100 ml / min at a temperature of 600 ° C for 2 h. After cooling to room temperature, the sample was taken out to obtain Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.6 Ni 0.6 @C composite specimen (see Figure 1 :Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.6 Ni 0.6 @C X-ray diffraction (XRD) test spectrum of the composite sample).

[0034] Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.6 Ni 0.6 After the alloy is carbon coated, a uniform carbon layer is formed on the surface (see Figure 2 :Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.6 Ni 0.6 @C scanning electron microscope image of the composite sample). At the same time, the D and G peaks in the Raman spectrum confirm the presence of graphitic carbon and a certain amount of defective carbon in the coating layer. This carbon layer structure improves both conductivity and catalytic activity (see Figure 3 :Ti 0.5 Zr 0.5 V 0.2 Mn0.2 Cr 0.4 Fe 0.6 Ni 0.6 @C Raman spectrum of the composite sample).

[0035] The results of the electrocatalytic oxygen evolution performance test at room temperature showed that in 1 mol / L KOH solution, 10 mA / cm 2 At this current density, the overpotential reaches 272 mV (see Figure 5 :Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.6 Ni 0.6 @C composite sample oxygen evolution reaction linear sweep voltammetry curve in 1 mol / L KOH electrolyte). In addition, the charge transfer resistance is only 1.235Ω (see Figure 6 :Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.6 Ni 0.6 @C composite sample in 1mol / L KOH electrolyte AC impedance diagram). The results of hydrogen absorption and desorption kinetics test show that Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.6 Ni 0.6 The @C composite sample can absorb 1.20wt.% of hydrogen at room temperature and release hydrogen almost completely at room temperature (see Figure 8 :Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.6 Ni 0.6 @C composite sample hydrogen absorption and desorption kinetics curve at 298K), which shows that the composite material has excellent oxygen evolution and hydrogen storage properties.

[0036] Example 3: Preparation of Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.2 Ni 1.0 High-entropy alloys (1) According to the chemical formula Ti 0.5 Zr0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.2 Ni 1.0 Weigh titanium, zirconium, vanadium, chromium, manganese, iron, and nickel blocks, respectively, with a total weight of 15 g. (2) 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 300A, the alloy is completely melted, then stop heating, keep warm for 5 minutes, then cool the alloy, turn the alloy ingot over, repeat the smelting 4 times, and you can get a uniform composition of Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.2 Ni 1.0 Precursor alloy ingot (see Figure 1 :Cast Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0. 4Fe 0.2 Ni 1.0 X-ray diffraction (XRD) test spectrum of high entropy alloy); (3) In a glove box, the obtained precursor alloy ingot was mechanically crushed into 200 mesh powder using a stainless steel mortar; (4) Weigh the crushed Ti using an analytical balance in a glove box. 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.2 Ni 1.0 5 g of alloy powder was placed in a ball mill at a ball-to-material ratio of 10:1 and subjected to high-energy ball milling at a speed of 400 r / min for 5 h. (5) Weigh the ball-milled Ti according to a mass ratio of 2:1 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.2 Ni 1.0 Add 30 ml of deionized water to the alloy powder and glucose powder, stir to dissolve, and ultrasonically mix for 1 hour; (6) Gradually add 0.02 mol / L NaOH solution to the mixed solution after ultrasonication and test with a pH meter until the solution pH reaches 9.0; (7) Place the mixed solution in a 50 ml polytetrafluoroethylene hydrothermal reactor and perform hydrothermal carbonization in a drying oven for 12 h at a temperature of 180 °C. After the reaction is completed, cool the mixture to room temperature in the oven, remove the mixture, centrifuge, wash, and vacuum dry. (8) The dried sample was placed in a tube furnace and calcined in an argon atmosphere with a gas flow rate of 100 ml / min at a temperature of 600 ° C for 2 h. After cooling to room temperature, the sample was taken out to obtain Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.2 Ni 1.0 @C composite specimen (see Figure 1 :Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.2 Ni 1.0 @C X-ray diffraction (XRD) test spectrum of the composite sample).

[0037] Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.2 Ni 1.0 After the alloy is carbon coated, a uniform carbon layer is formed on the surface (see Figure 2 :Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.2 Ni 1.0 @C scanning electron microscope image of the composite sample). At the same time, the D and G peaks in the Raman spectrum confirm the presence of graphitic carbon and a certain amount of defective carbon in the coating layer. This carbon layer structure improves both conductivity and catalytic activity (see Figure 3 :Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.2 Ni 1.0 @C Raman spectrum of the composite sample).

[0038] The nitrogen adsorption and desorption diagram shows that there is a certain pore structure on the surface of the composite sample, which helps to expose more active sites and accelerate the hydrogen absorption and desorption rate. Its BET specific surface area is 4.48m 2 / g, and the BJH desorption cumulative specific surface area is 14.9064m 2 / g.

[0039] The results of the electrocatalytic oxygen evolution performance test at room temperature showed that in 1 mol / L KOH solution, 10 mA / cm 2 At this current density, the overpotential reaches 267mV (see Figure 5 :Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.2 Ni 1.0 @C composite sample oxygen evolution reaction linear sweep voltammetry curve in 1 mol / L KOH electrolyte). In addition, the charge transfer resistance is only 0.989Ω (see Figure 6 :Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.2 Ni 1.0 @C composite sample in 1mol / L KOH electrolyte AC impedance diagram). The results of hydrogen absorption and desorption kinetics test show that Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.2 Ni 1.0 The @C composite sample can absorb 1.21wt.% of hydrogen at room temperature and completely release hydrogen at room temperature (see Figure 8 :Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.2 Ni 1.0 @C composite sample hydrogen absorption and desorption kinetics curve at 298K), which shows that the composite material has excellent oxygen evolution and hydrogen storage properties.

[0040] Comparative Example 1: Preparation of Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 0.1 Ni 1.1 High entropy alloy composites The difference between Comparative Example 1 and Example 1 is that x=0.1. The electrocatalytic oxygen evolution performance test of the prepared alloy composite material is carried out. The results show that in 1 mol / L KOH solution, 10 mA / cm 2 The overpotential reached 288 mV at the current density. The results of hydrogen absorption and desorption kinetics tests showed that the material could absorb 1.10 wt.% of hydrogen at room temperature, but did not completely desorb hydrogen at room temperature, indicating that the oxygen evolution and hydrogen storage performance of the alloy composite material in this comparative example was not ideal.

[0041] Comparative Example 2: Preparation of Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 1.1 Ni 0.1 High entropy alloy composites The difference between Comparative Example 2 and Example 1 is that x=1.1. The electrocatalytic oxygen evolution performance test of the prepared alloy composite material is carried out. The results show that in 1 mol / L KOH solution, 10 mA / cm 2 The overpotential reached 311 mV at the current density. The results of hydrogen absorption and desorption kinetics tests showed that the material could absorb 1.0 wt.% of hydrogen at room temperature, but did not completely desorb hydrogen at room temperature, indicating that the oxygen evolution and hydrogen storage performance of the alloy composite material in this comparative example was not ideal.

[0042] Comparative Example 3: Preparation of Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Ni 1.2 High entropy alloy composites The difference between Comparative Example 3 and Example 1 is that x=0. The electrocatalytic oxygen evolution performance test of the prepared alloy composite material is carried out. The results show that in 1 mol / L KOH solution, 10 mA / cm 2 The overpotential reached 295mV at the current density. The results of hydrogen absorption and desorption kinetics test showed that it could absorb 1.04wt.% of hydrogen at room temperature, but did not fully desorb hydrogen at room temperature, indicating that the oxygen evolution and hydrogen storage performance of the alloy composite material in this comparative example was not ideal.

[0043] Comparative Example 4: Preparation of Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe 1.2 High entropy alloy composites Overpotential 311mV, hydrogen storage capacity 0.96wt.% The difference between Comparative Example 2 and Example 1 is that x=1.2. The electrocatalytic oxygen evolution performance test of the prepared alloy composite material is carried out. The results show that in 1 mol / L KOH solution, 10 mA / cm 2 The overpotential reached 320 mV at the current density. The results of hydrogen absorption and desorption kinetics test showed that it could absorb 0.93 wt.% of hydrogen at room temperature, but did not completely desorb hydrogen at room temperature, indicating that the oxygen evolution and hydrogen storage performance of the alloy composite material in this comparative example was not ideal.

[0044] 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 carbon-coated high-entropy alloy composite material, characterized in that: The alloy composite material has an alloy molecular formula of Ti according to the atomic molar ratio content. 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe x Ni 1.2-x @C, where x = 0.2~1.0, the specific surface area is 14.9064 m 2 / g.

2. A method for preparing the carbon-coated high-entropy alloy composite material according to claim 1, characterized in that: The specific steps are as follows: (1) According to the molecular formula of the alloy composite material Ti 0.5 Zr 0.5 V 0.2 Mn 0.2 Cr 0.4 Fe x Ni 1.2-x @C, weigh titanium block, zirconium block, vanadium block, chromium block, iron block, nickel block and manganese sheet; (2) In an argon atmosphere, place the prepared metal raw materials in the crucible from bottom to top according to their melting points, and then -2 Arc vacuum melting is performed under a vacuum degree of Pa. After the alloy is completely melted and cooled, the formed alloy ingot is turned over and repeatedly melted 3 to 4 times to obtain a cast high entropy precursor alloy ingot. (3) In a glove box, crush the precursor alloy ingot in a stainless steel mortar and grind it into 200-300 mesh alloy powder; (4) In a glove box, weigh the precursor alloy powder and add it to a ball milling jar, and perform high-energy ball milling on a planetary ball mill to obtain a refined precursor alloy powder sample; (5) Weigh the ball-milled precursor powder and glucose powder, add deionized water, stir thoroughly, and perform ultrasonic treatment; (6) Adding alkaline solution to the mixed liquid to adjust the pH value; (7) The mixed solution is placed in a polytetrafluoroethylene reactor and subjected to hydrothermal carbonization reaction in a drying oven. After the reaction is completed, the mixture is cooled to room temperature in the oven, taken out, centrifuged, washed, and vacuum dried. (8) The dried composite sample is placed in a tubular furnace and calcined under an argon atmosphere. After the calcination is completed, the sample is cooled to room temperature and then taken out to finally obtain a carbon-coated high-entropy alloy composite material.

3. The method for preparing the carbon-coated high-entropy alloy composite material according to claim 2, wherein: In the step (1), considering that the titanium block and the manganese sheet are burned during the arc melting process, 2 wt.% of the titanium block and 5 wt.% of the manganese sheet are additionally added.

4. The method for preparing the carbon-coated high-entropy alloy composite material according to claim 2, wherein: In the step (3), the ball mill process has a ball-to-material ratio of 10-30:1 and a rotation speed of 350-450 r / min.

5. The method for preparing the carbon-coated high-entropy alloy composite material according to claim 2, wherein: In step (4), the mass ratio of the precursor alloy powder to the glucose powder is 2:1, the volume of the mixed solution is 30-40 ml, and the ultrasonic time is 30-60 min.

6. The method for preparing the carbon-coated high-entropy alloy composite material according to claim 2, wherein: In the step (5), the pH is adjusted to 8-10, and the alkaline solution includes but is not limited to one of ammonia water and sodium hydroxide.

7. The method for preparing the carbon-coated high-entropy alloy composite material according to claim 2, wherein: In step (6), the hydrothermal carbonization reaction process is at a temperature of 160-180° C. and a time of 5-12 hours.

8. The method for preparing the carbon-coated high-entropy alloy composite material according to claim 2, wherein: In the step (7), the calcination process is performed at a temperature of 400-600° C. and a time of 2-3 hours.

9. Use of the carbon-coated high entropy alloy composite material in oxygen evolution according to claim 1, characterized in that: The composite material was drop-coated on carbon paper and used as a working electrode for oxygen electrolysis in an alkaline electrolyzer. In a 1 mol / L KOH solution, the overpotential at a current density of 10 mA / cm² was 267-283 mV, and the charge transfer resistance was 0.989-1.476 Ω, showing excellent electrochemical stability within 98 hours.

10. Use of the carbon-coated high entropy alloy composite material in hydrogen storage according to claim 1, characterized in that: Before the hydrogen storage function of this composite material was demonstrated, after three cycles of hydrogen absorption and desorption at 300°C and 4MPa pressure, the hydrogen storage capacity reached 1.17-1.21wt.%, and complete hydrogen absorption could be achieved within 100s and complete hydrogen desorption within 150s at room temperature.

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