Biomass-derived N and O-containing biochar-encapsulated high-entropy alloy catalyst as well as preparation method and application of biomass-derived N and O-containing biochar-encapsulated high-entropy alloy catalyst

Abstract

The invention belongs to the field of electro-catalytic materials, and discloses a biomass-derived N and O-containing biochar encapsulated Fe-Co-Ni-Cu high-entropy alloy catalyst and a preparation method and application thereof, the catalyst is especially suitable for efficient alkaline oxygen evolution reaction (OER), and the method comprises the following steps: biomass pretreatment; preparing a high-entropy alloy precursor solution; dipping and drying; and calcining and alloying. The high-entropy alloy (HEAs) biomass charcoal formed by transition metals Fe, Co, Ni and Cu loaded on the biomass charcoal is prepared by adopting a simple impregnation-pyrolysis strategy and serves as a renewable carbon source, and the biomass charcoal not only has a rich pore structure and a high specific surface area, but also has good electrical conductivity and thermal stability, and can be used as a renewable carbon source. A good substrate is provided for loading of transition metal, uniform distribution and efficient utilization of metal particles are facilitated, and excellent OER performance and long-term stability are achieved.

Description

Technical Field

[0001] The present invention belongs to but is not limited to the field of electrocatalytic materials, and specifically relates to a biomass-derived N, O-containing biochar encapsulated iron-cobalt-nickel-copper high-entropy alloy catalyst and a preparation method and application thereof, which is particularly suitable for efficient alkaline oxygen evolution reaction (OER). Background Art

[0002] With the continuous growth of fossil fuel consumption, environmental pollution problems are becoming more and more serious, and the demand for sustainable green energy has become more and more urgent. Electrocatalytic water splitting technology has attracted much attention because it can convert water resources into clean energy hydrogen. In the past few decades, researchers have conducted in-depth research on electrocatalytic water splitting technology and made significant progress. Among them, the oxygen evolution reaction (OER), as the core half-reaction in the electrocatalytic water splitting process, is a key step in achieving water splitting to produce hydrogen energy. However, the OER process involves complex kinetic mechanisms and usually requires a large overpotential to achieve the required current density, which undoubtedly increases the difficulty and cost in practical applications. At present, commercial OER electrocatalysts mainly rely on precious metals, such as ruthenium (Ru) and iridium (Ir). Although these precious metal electrocatalysts have excellent performance in terms of activity, their high cost, scarcity of resources and instability under operating conditions have severely limited their widespread application.

[0003] As a new type of material, high entropy alloys (HEAs) have shown great potential in the field of electrocatalysis due to their unique composition and structural characteristics. High entropy alloy catalysts are composed of multiple metal elements and have high entropy characteristics. They can break the property limitations of a single element and show excellent catalytic performance. However, the preparation method of existing high entropy alloy catalysts is complicated, and the combination with the carrier is not tight enough, which affects its practical application effect. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention adopts a simple impregnation-pyrolysis strategy to prepare high entropy alloys (HEAs) formed by transition metals Fe, Co, Ni, and Cu loaded on biochar. As a renewable carbon source, biochar not only has a rich pore structure and a high specific surface area, but also has good electrical conductivity and thermal stability, providing a good substrate for the loading of transition metals, which is conducive to the uniform distribution and efficient utilization of metal particles, and has excellent OER performance and long-term stability.

[0005] The present invention is achieved by providing a biomass-derived high entropy alloy catalyst encapsulated with N and O biochar and a preparation method thereof, the method comprising:

[0006] S1: providing a biomass raw material and pre-treating it, wherein the pre-treating step comprises: using a cutter to remove the outer thick skin and impurities of the biomass material (such as grapefruit peel), washing it with distilled water for multiple times, drying it at 60-100° C. for 8-12 hours, and then grinding the dried biomass into a uniform powder using a pulverizer to ensure that the impurity content is low in the subsequent carbonization process and the N and O functional groups are retained;

[0007] S2: preparing a high entropy alloy precursor solution, characterized in that Fe(NO 3 ) 2 9H 2 O、Co(NO 3 ) 2 6H 2 O.Ni(NO 3 ) 2 6H 2 O, Cu(NO 3 ) 2 ·3H 2 O is dissolved in a specified volume of water (e.g., 40.0 mL) in an equimolar ratio, stirred to form a uniform solution, and the concentration of the solution is adjusted to ensure that the metal ions are fully present;

[0008] S3: The biomass powder obtained in step S1 is appropriately carbonized under an inert atmosphere to prepare biochar containing N and O functional groups, and then the biochar is fully impregnated with the high entropy alloy precursor solution prepared in step S2 to ensure that the biochar fully adsorbs the metal ions, and then the impregnated mixture is dried to remove the solvent and fix the precursor in the biochar pores;

[0009] S4: The dried sample obtained in step S3 is heated under Ar / H 2 The mixture is heated to 600-1000°C at a heating rate of 5°C / min under a mixed atmosphere and kept at this temperature for 1.5-2.5 hours, so that the metal ions generate high-entropy alloy nanoparticles in the reduction reaction, and under the encapsulation effect of the biochar, a uniformly dispersed high-entropy alloy catalyst with controlled particle size is formed.

[0010] Through the above steps, the present method not only realizes a basic process similar to the catalyst preparation method disclosed in the existing public documents, but also refines and optimizes the pretreatment, impregnation, drying and calcination process parameters, thereby ensuring that the prepared high entropy alloy catalyst has outstanding catalytic activity and stability in composition and structure, which is different from the technical solutions in the comparative documents that only involve single or partial metal element loading.

[0011] Further, the S1 specifically includes:

[0012] Before using the grapefruit peel, remove the thick outer skin with a knife and wash it three times with distilled water to remove any impurities; then, dry the obtained grapefruit peel at 60-100°C for 8-12 hours and crush it with a grinder for later use.

[0013] Further, the S2 specifically comprises: Fe(NO 3 ) 2 9H 2 O,Co(NO 3 ) 2 6H 2 O,Ni(NO 3 ) 2 6H 2 O, Cu(NO 3 ) 2 ·3H 2 O was dissolved in 40.0 mL of aqueous solution in an equimolar ratio to form a uniform high entropy alloy precursor solution.

[0014] Further, the S3 specifically includes:

[0015] The N and O-containing biochar is immersed in a high entropy alloy precursor solution to allow it to fully adsorb metal ions, and then taken out and dried.

[0016] Further, the S4 specifically includes:

[0017] The dried biochar containing metal ions was heated in an Ar / H 2 The mixture was calcined at a heating rate of 5°C / min for 1.5 to 2.5 h under a carbon atmosphere. During the calcination, the metal ions underwent a reduction reaction and combined with the carbon element in the biochar to form high entropy alloy nanoparticles, which were encapsulated by the biochar shell.

[0018] Another object of the present invention is to provide a biomass-derived N, O-containing biochar-encapsulated high entropy alloy catalyst and a preparation system thereof based on the biomass-derived N, O-containing biochar-encapsulated high entropy alloy catalyst and a preparation method thereof, the system specifically comprising:

[0019] In the biomass pretreatment module, before using the grapefruit peel, the thick outer skin is removed with a knife and washed three times with distilled water to remove any impurities; then, the obtained grapefruit peel is dried at 60-100°C for 8-12h and then crushed with a grinder for later use.

[0020] The high entropy alloy precursor solution preparation module is connected to the biomass pretreatment module to convert Fe(NO 3 ) 2 9H 2 O,Co(NO 3 ) 2 6H 2 O,Ni(NO3 ) 2 6H 2 O, Cu(NO 3 ) 2 ·3H 2 O was dissolved in 40.0 mL of aqueous solution in an equimolar ratio to form a uniform high entropy alloy precursor solution;

[0021] The impregnation and drying module is connected to the high entropy alloy precursor solution preparation module, and the biochar containing N and O is impregnated in the high entropy alloy precursor solution to allow it to fully adsorb metal ions, and then taken out for drying;

[0022] The calcination and alloying module is connected to the impregnation and drying module to immerse the dried biochar containing metal ions in an Ar / H 2 The mixture was calcined at a heating rate of 5°C / min for 1.5 to 2.5 h under a carbon atmosphere. During the calcination, the metal ions underwent a reduction reaction and combined with the carbon element in the biochar to form high entropy alloy nanoparticles, which were encapsulated by the biochar shell.

[0023] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0024] First, biochar has a rich pore structure and a large specific surface area. This feature enables it to provide a good adsorption and penetration environment for alloy elements in the process of preparing high entropy alloy catalysts, thereby achieving uniform distribution and comprehensive contact of alloy elements and ensuring the uniformity of alloying effects. At the same time, biochar has a wide range of sources and can be prepared using biomass resources such as agricultural waste and wood processing residues. It not only effectively utilizes renewable resources, but also reduces the pollution of waste to the environment, and has significant economic and social benefits.

[0025] Carbon materials themselves exhibit excellent thermal and chemical stability, allowing biochar to maintain its structural integrity under high temperature and corrosive conditions. In the manufacturing process of high-entropy alloys, this stability can effectively resist the deformation and damage caused by high-temperature calcination, ensuring the structural support of biochar as a template, thereby ensuring the high quality and performance stability of the final catalyst.

[0026] In the synthesis process of high entropy alloys, biochar, as a green and efficient reducing agent, significantly improves the purity and uniformity of the alloy. Compared with traditional methods, the reduction process of biochar is milder and can minimize the risk of volatilization and oxidation of metal elements at high temperatures, ensuring the fine distribution of alloy components. At the same time, this benign reduction process also makes the preparation process more environmentally friendly, further improving the sustainability of the preparation technology.

[0027] Using biochar as a template can significantly simplify the preparation process of high entropy alloy catalysts. Unlike traditional preparation methods that require complex equipment and cumbersome procedures, the application of biochar templates reduces unnecessary steps and improves preparation efficiency by optimizing the process. In addition, due to the economy and renewability of biochar templates, the overall preparation cost is greatly reduced, making this method more potential for industrial application.

[0028] Second, as auxiliary evidence of the inventiveness of the claims of the present invention, it is also reflected in the following important aspects:

[0029] (1) The expected benefits and commercial value of the technical solution of the present invention after transformation are:

[0030] Expected benefits include:

[0031] 1. The FeCoNiCu high entropy alloy catalyst can optimize the electronic structure and regulate the adsorption energy of reaction intermediates (such as HOO*) through the synergistic effect of multiple transition metals, achieving dual activation and stabilization, thereby reducing the reaction energy barrier and accelerating the kinetics of the oxygen evolution reaction. This high-performance catalyst can reduce the cost of hydrogen production by water electrolysis and improve energy conversion efficiency, thus bringing significant economic benefits.

[0032] 2. The high entropy alloy catalyst exhibits excellent long-term stability under alkaline conditions and can be used at a current density of 20 mA cm - Under the operating conditions of 2, the performance did not decline significantly after continuous operation for more than 60 hours. This stability reduces the frequency of catalyst replacement, reduces maintenance costs, and further improves economic benefits.

[0033] 3. The preparation cost of biochar is relatively low and its source is wide. Using biochar as a template can reduce the overall cost of the catalyst. Compared with traditional precious metal catalysts, this biochar-based high entropy alloy catalyst has obvious cost advantages in large-scale applications.

[0034] Business value includes:

[0035] 1. The high efficiency of high entropy alloy catalysts in alkaline oxygen evolution reaction makes them a key material in the field of water electrolysis hydrogen production. With the rapid development of renewable energy (such as solar energy and wind energy), water electrolysis hydrogen production has great market potential as an effective way to convert renewable energy into hydrogen energy. The transformation of this technical solution will help promote the development of water electrolysis hydrogen production technology and meet the market demand for clean energy.

[0036] 2. The use of biochar not only achieves efficient utilization of biomass resources, but also reduces the pollution of waste to the environment, which is in line with the concept of green manufacturing. This environmentally friendly technical solution has advantages in market competition, can meet the market demand for environmentally friendly products, and enhance the brand image of the enterprise.

[0037] 3. The application of high entropy alloy catalysts in fuel cells and energy storage devices also brings important commercial value. For example, in zinc-air batteries, high entropy alloy catalysts as anode materials can maintain efficient oxygen evolution reactions at high current densities and improve battery performance and stability. This will help promote the development of fuel cells and energy storage technologies and expand their applications in electric vehicles, distributed energy and other fields.

[0038] (2) The technical solution of the present invention fills the technical gap in the industry at home and abroad:

[0039] At present, the application research of high entropy alloys in alkaline oxygen evolution reaction is still in the development stage. Biochar, as a green and low-cost template material, has rich pore structure and good conductivity, and can provide an ideal carrier for the loading of high entropy alloys. This combination has not been widely reported in domestic and foreign research and is highly innovative. In addition, the successful implementation of this technical solution will also help promote scientific and technological progress and industrial development in related fields. On the one hand, it can promote the extension and development of the biochar industry chain and form a synergistic effect with the clean energy industry; on the other hand, it can also provide new ideas and methods for the preparation of catalysts in other fields, and promote the innovation and progress of related technologies.

[0040] (3) The technical solution of the present invention solves the technical problems that people have been eager to solve but have never been able to solve successfully:

[0041] The alkaline oxygen evolution reaction is a key step in clean energy technologies such as water electrolysis to produce hydrogen, but traditional catalysts often have problems such as insufficient activity and poor stability. By using biochar as a template to prepare a high-entropy alloy catalyst, the catalyst activity was significantly improved and the stability was enhanced, providing an efficient and stable catalyst material for the alkaline oxygen evolution reaction. At the same time, as a form of utilization of renewable resources, the application of biochar helps to reduce dependence on traditional energy and environmental pollution. This technical solution provides a more environmentally friendly solution for the development of clean energy technology by realizing the high-value utilization of biochar.

[0042] (4) The technical solution of the present invention overcomes technical prejudice:

[0043] Traditionally, the preparation of high entropy alloys often focuses on the design of alloy components and the optimization of synthesis processes, while the choice of supporting substrates is relatively limited. Using biochar as a template not only provides a unique loading platform for high entropy alloys, but also makes full use of the porous structure, high specific surface area and excellent electrical conductivity of biochar. These characteristics help to improve the catalytic activity and stability of high entropy alloys in alkaline oxygen evolution reactions. In addition, this technical solution also breaks through the previous limitations of knowledge about catalyst support materials. As a renewable resource, biochar is widely available, low-cost, and can have excellent catalytic support performance after proper treatment. This not only reduces the preparation cost of the catalyst, but also provides new possibilities for the industrial application of high entropy alloy catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a flow chart of a biomass-derived N, O-containing biochar-encapsulated high entropy alloy catalyst and a preparation method thereof provided by an example of the present invention;

[0045] Figure 2 This is a low-magnification transmission electron micrograph of a biomass-derived N and O-containing biochar encapsulated iron-cobalt-nickel-copper high-entropy alloy catalyst obtained in an example of the present invention;

[0046] Figure 3 It is a high-resolution transmission electron micrograph of a biomass-derived N and O-containing biochar encapsulated iron-cobalt-nickel-copper high-entropy alloy catalyst obtained in an example of the present invention;

[0047] Figure 4 It is an X-ray diffraction pattern of the biomass-derived N and O-containing biochar encapsulated iron-cobalt-nickel-copper high entropy alloy catalyst obtained in an example of the present invention;

[0048] Figure 5 It is an OER polarization curve diagram of the biomass-derived N and O-containing biochar encapsulated iron-cobalt-nickel-copper high entropy alloy catalyst obtained in an example of the present invention;

[0049] Figure 6 It is a cyclic stability curve diagram of the biomass-derived N, O-containing biochar encapsulated iron-cobalt-nickel-copper high-entropy alloy catalyst obtained in an example of the present invention. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0051] like Figure 1 As shown, an embodiment of the present invention provides a biomass-derived high entropy alloy catalyst encapsulated with N and O-containing biochar and a preparation method thereof, the method comprising:

[0052] S1: biomass pretreatment;

[0053] S2: preparation of high entropy alloy precursor solution;

[0054] S3: impregnation and drying;

[0055] S4: Calcination and alloying. The calcination temperature is 600℃~1000℃.

[0056] Biomass pretreatment is the basic step in the preparation of high entropy alloy catalysts. Biomass rich in C, N, and O elements (such as lignocellulose, algae, or waste plant residues) is selected for preliminary treatment. During the pretreatment process, the biomass is washed, dried, crushed, etc. to remove impurities and excess water, and granulated to give it a good adsorption performance on the surface, thereby providing a suitable carrier for the subsequent uniform impregnation of the high entropy alloy precursor solution.

[0057] The preparation of high entropy alloy precursor solution is to dissolve a variety of metal salts (such as iron salts, nickel salts, cobalt salts, manganese salts, copper salts, etc.) in water or appropriate solvents in a specific proportion to form a solution with uniform distribution of multi-metal ions. In order to improve the alloying effect, a chelating agent or cosolvent can be added to ensure the mutual uniformity and stability between metal ions. The metal ions in the solution will be closely combined with the biomass carrier in the subsequent process, and finally form high entropy alloy particles uniformly distributed in the biochar structure.

[0058] During the impregnation process, the biomass carrier is fully in contact with the high entropy alloy precursor solution, and the metal ions in the solution are adsorbed by the active sites on the biomass surface to achieve uniform loading. After the impregnation is completed, the impregnated biomass is placed in a drying device and slowly dried at a suitable temperature (such as 60-100°C) to ensure that the metal ions are evenly distributed and firmly bonded, while maintaining the structural integrity of the biomass, providing a stable precursor for the subsequent calcination step.

[0059] Calcination is a key step in the preparation process. The precursor after impregnation and drying is placed in a high-temperature inert atmosphere (such as argon and nitrogen) for calcination. During the calcination process, the biomass undergoes pyrolysis to generate porous biochar containing N and O elements; at the same time, the metal salts in the precursor decompose into metal oxides, and undergo reduction reactions and diffusion alloying at high temperatures to form high-entropy alloy particles with multiple metals evenly distributed. The high-entropy alloy particles have excellent thermal stability and catalytic activity through the encapsulation of biochar, and the N and O functional groups in the biochar can effectively enhance the electronic structure regulation ability of the catalyst.

[0060] The S1 specifically includes:

[0061] Before using the grapefruit peel, remove the thick outer skin with a knife and wash it three times with distilled water to remove any impurities; then, dry the obtained grapefruit peel at 60-100°C for 8-12 hours and crush it with a grinder for later use.

[0062] The S2 specifically comprises: Fe(NO 3 ) 2 9H 2 O,Co(NO 3 ) 2 6H 2 O,Ni(NO 3 ) 2 6H 2 O, Cu(NO 3 ) 2 ·3H 2 O was dissolved in 40.0 mL of aqueous solution in an equimolar ratio to form a uniform high entropy alloy precursor solution.

[0063] The S3 specifically includes:

[0064] The N and O-containing biochar is immersed in a high entropy alloy precursor solution to allow it to fully adsorb metal ions, and then taken out and dried.

[0065] The S4 specifically includes:

[0066] The dried biochar containing metal ions was heated in an Ar / H 2 The mixture was calcined at a heating rate of 5°C / min for 1.5 to 2.5 h under a carbon atmosphere. During the calcination, the metal ions underwent a reduction reaction and combined with the carbon element in the biochar to form high entropy alloy nanoparticles, which were encapsulated by the biochar shell.

[0067] The embodiment of the present invention provides a biomass-derived N, O-containing biochar-encapsulated high-entropy alloy catalyst and a preparation system thereof based on the biomass-derived N, O-containing biochar-encapsulated high-entropy alloy catalyst and a preparation method thereof, and the system specifically comprises:

[0068] In the biomass pretreatment module, before using the grapefruit peel, the thick outer skin is removed with a knife and washed three times with distilled water to remove any impurities; then, the obtained grapefruit peel is dried at 60-100°C for 8-12h and then crushed with a grinder for later use.

[0069] The high entropy alloy precursor solution preparation module is connected to the biomass pretreatment module to convert Fe(NO 3 ) 2 9H 2 O,Co(NO 3 ) 2 6H 2 O,Ni(NO 3 )2 6H 2 O, Cu(NO 3 ) 2 ·3H 2 O was dissolved in 40.0 mL of aqueous solution in an equimolar ratio to form a uniform high entropy alloy precursor solution;

[0070] The impregnation and drying module is connected to the high entropy alloy precursor solution preparation module, and the biochar containing N and O is impregnated in the high entropy alloy precursor solution to allow it to fully adsorb metal ions, and then taken out for drying;

[0071] The calcination and alloying module is connected to the impregnation and drying module to immerse the dried biochar containing metal ions in an Ar / H 2 The mixture was calcined at a heating rate of 5°C / min for 1.5 to 2.5 h under a carbon atmosphere. During the calcination, the metal ions underwent a reduction reaction and combined with the carbon element in the biochar to form high entropy alloy nanoparticles, which were encapsulated by the biochar shell.

[0072] This module is used to process grapefruit peel as a precursor to obtain biochar suitable for loading high entropy alloys. First, the outer peel is removed and the washing process is performed to remove impurities and water-soluble interfering components to ensure the purity of the biomass. Subsequently, it is dried at 60-100°C to completely evaporate the water inside the grapefruit peel and reduce the instability of gas release during its heat treatment. Finally, a grinder is used to crush the dried grapefruit peel into micron-sized particles to increase the specific surface area and provide a good carrier material for the subsequent adsorption and uniform dispersion of metal ions.

[0073] The core of this module is to prepare a uniformly distributed high entropy alloy metal precursor solution. 3 ) 2 9H 2 O,Co(NO 3 ) 2 6H 2 O,Ni(NO 3 ) 2 6H 2 O and Cu(NO 3 ) 2 ·3H 2 Metal precursors such as O are dissolved in water in an equimolar ratio to ensure that the atomic ratio of each metal element is consistent. Through continuous stirring or ultrasonic treatment, the metal salts are evenly dispersed to avoid precipitation or precipitation, thereby obtaining a stable metal precursor solution. In the subsequent steps, the metal ions in the solution will be evenly adsorbed on the surface of biochar, laying the foundation for the subsequent alloying process.

[0074] In this module, N and O-containing biochar is completely immersed in the high entropy alloy precursor solution. The adsorption is enhanced by static adsorption or stirring, so that the metal ions evenly penetrate into the pores of the biochar and complex with the functional groups on its surface (such as carbonyl, hydroxyl, amino, etc.) to increase the metal loading capacity. After adsorption saturation, the biochar is taken out and dried at 100°C to evaporate the water and further fix the metal ions on the surface of the biochar to ensure uniform alloying during the subsequent calcination process.

[0075] This module is the key part of the whole system, which realizes the formation of high entropy alloy nanoparticles through high temperature reduction calcination. 2 In an inert gas / reducing gas atmosphere, the temperature is raised to 600-1000°C at a rate of 5°C / min and maintained for 1.5-2.5h. In this process, the metal ions are replaced by H 2 Reduced to zero-valent metals, they diffuse and crystallize each other under high temperature conditions to form high-entropy alloy nanoparticles. At the same time, the carbon structure of biochar is partially graphitized, which enhances the conductivity of the material and forms a porous structure, so that the high-entropy alloy particles are evenly encapsulated by the biochar shell, thereby improving the stability and durability of the catalyst.

[0076] Figure 2 This is a low-magnification transmission electron microscope image of the FeCoNiCu / NOC sample. Figure 3 This is a high-resolution transmission electron microscopy image of the FeCoNiCu / NOC sample. Figure 2 The distribution of metal nanoparticles on the graphite carbon layer is shown. It can be seen from the figure that after the confinement effect of the nitrogen-doped ordered mesoporous carbon template, the catalyst nanoparticles are evenly dispersed on the biomass carbon carrier, and the nanoparticles do not have serious agglomeration phenomenon, which shows that the metal particles and graphitized carbon work together, and the strong interaction between them fixes the metal nanoparticles on the corresponding carbon base, avoiding the agglomeration of particles. At the same time, it can be observed that part of the metal is wrapped by the self-doped N graphitized carbon layer with a thickness of about 5 layers. This is attributed to the fact that during the carbonization process, this thin graphene shell not only prevents the further oxidation of the metal nanoparticles, but also promotes the transfer of electrons from the inside to the shell, thereby improving the surface activity of the electrocatalyst.

[0077] The FeCoNiCu / NOC sample obtained in this example was subjected to X-ray diffraction ( Figure 4 ) analysis shows that since the transition metals used all belong to the FCC face-centered cubic structure, the prepared high entropy alloy also follows the FCC structure. It can be seen that the FeCoNiCu / NOC sample produces obvious metal diffraction characteristic peaks at 2θ=43.7°, 51.2° and 75.9°, which correspond to the (111), (200), and (220) crystal planes of the Fm-3m FCC structure, respectively, proving that a single-phase Fe-Co-Nickel-Cu HEAs material has been formed.

[0078] Furthermore, the FeCoNiCu / NOC sample obtained in this example was tested for its oxygen production performance by water electrolysis. Figure 5 Linear sweep voltammetry (LSV) curve of FeCoNiCu / NOC HEAs catalyst at a scan rate of 5 mV s -1 , the current density is 10 mA cm -2 When the OER is carried out, the overpotential of the FeCoNiCu / NOC catalyst is 300mV. The catalyst exhibits excellent OER performance, which may be due to its unique composition and structure. When OER is carried out, the synergistic effect of multiple metal elements enables its surface to form a variety of metal oxygen-containing active centers during the electrocatalytic process. Figure 6 This is the cyclic stability test curve of FeCoNiCu / NOC sample. In 1M KOH solution, 20mA cm -2 The catalytic activity of the sample remained almost unchanged after cycling for 60 h at the current density, indicating that the prepared FeCoNiCu / NOC catalyst has good cycling stability.

[0079] Example 1: Preparation method of FeCoNiCu high entropy alloy catalyst encapsulated by N and O biochar derived from grapefruit peel

[0080] 1. Biomass pretreatment (S1)

[0081] Select fresh grapefruit peel, remove the skin with a knife, and then wash it three times with distilled water.

[0082] Place the cleaned grapefruit peel in an oven at 60-100°C and dry for 8-12 hours until it is completely dehydrated.

[0083] The dried grapefruit peel was crushed into powder using a grinder and passed through an 80-mesh sieve to obtain a uniform biomass precursor powder.

[0084] 2. Preparation of high entropy alloy precursor solution (S2)

[0085] Prepare metal precursor solution and mix Fe(NO 3 ) 2 9H 2 O,Co(NO 3 ) 2 6H 2 O,Ni(NO 3 ) 2 6H 2 O, Cu(NO 3 ) 2 ·3H 2 O was weighed in an appropriate amount according to an equimolar ratio and dissolved in 40.0 mL of deionized water.

[0086] Ultrasonic stirring was performed at 25° C. for 30 min to uniformly disperse the solution and completely dissolve the solution to obtain a high entropy alloy precursor solution.

[0087] 3. Impregnation and drying (S3)

[0088] Take 3-6 g of biomass powder (grapefruit peel powder) and put it into a beaker, add the high entropy alloy precursor solution, keep stirring at room temperature for 12 hours, so that the metal ions can be fully impregnated into the biomass.

[0089] The impregnated biomass powder was taken out and dried in an oven at 100°C for 6 h to ensure complete removal of moisture.

[0090] 4. Calcination and alloying (S4)

[0091] Ar / H2 was introduced into the tube furnace. 2 The dried sample was heated to 600-1000°C at a heating rate of 5°C / min and calcined for 1.5-2.5h.

[0092] During the calcination process, metal ions are reduced and react with the carbon element in the biochar to form nanoscale high-entropy alloy particles, which are encapsulated in the biochar carrier.

[0093] The mixture was naturally cooled to room temperature, and the catalyst powder was taken out to obtain the FeCoNiCu high entropy alloy catalyst encapsulated by the pomelo peel-derived N and O-containing biochar.

[0094] 5. Product Characterization

[0095] X-ray diffraction (XRD) was used to analyze the alloy crystal structure.

[0096] The size and distribution of the nanoparticles were observed by transmission electron microscopy (TEM).

[0097] X-ray photoelectron spectroscopy (XPS) was used to analyze the element content and chemical state on the catalyst surface.

[0098] Example 2: Preparation of FeCoNiCuZn high entropy alloy catalyst encapsulated by pine needle-derived N and O-containing biochar

[0099] 1. Biomass pretreatment (S1)

[0100] Natural pine needles and leaves were selected, cut into pieces, and washed three times with deionized water to remove surface dust and impurities.

[0101] Place the cleaned pine needles in an oven at 100°C and dry for 12 hours.

[0102] The dried pine needles were ground using a ball mill and passed through a 100-mesh sieve to prepare uniform pine needle biomass powder.

[0103] 2. Preparation of high entropy alloy precursor solution (S2)

[0104] Prepare metal precursor solution and mix Fe(NO 3 ) 2 9H 2 O,Co(NO 3 ) 2 6H 2 O,Ni(NO 3 ) 2 6H 2 O, Cu(NO 3 ) 2 ·3H 2 O, Zn(NO 3 ) 2 6H 2 O was weighed in an appropriate amount according to an equimolar ratio and dissolved in 40.0 mL of deionized water.

[0105] The mixture was stirred magnetically for 60 min at room temperature to form a uniform and transparent high entropy alloy precursor solution.

[0106] 3. Impregnation and drying (S3)

[0107] Take 3-6 g of pine needle biomass powder, add high entropy alloy precursor solution, and stir at room temperature for 12 h to promote the full adsorption of metal ions.

[0108] Take out the impregnated sample, put it into an oven, and dry it at 60-100°C for 8h.

[0109] 4. Calcination and alloying (S4)

[0110] In the tube furnace, N 2 / H 2 (90:10, volume ratio) protective atmosphere, heat the sample to 600-1000°C at a heating rate of 5°C / min and calcine for 1.5-2.5h.

[0111] During the reduction process, high entropy alloy nanoparticles precipitated in the biochar carrier and formed uniformly distributed catalytic active sites.

[0112] After calcination, the mixture was naturally cooled to room temperature and ground to obtain the pine needle-derived N and O-containing biochar-encapsulated FeCoNiCuZn high entropy alloy catalyst.

[0113] 5. Product Characterization

[0114] Scanning electron microscopy (SEM) was used to analyze the micromorphology of the catalyst.

[0115] The pore structure of the catalyst was analyzed by BET specific surface area method.

[0116] The electrochemical activity of the catalysts was tested by cyclic voltammetry (CV).

[0117] Example 1: Using grapefruit peel as a biomass precursor to prepare FeCoNiCu high entropy alloy catalyst, the calcination temperature is 600-1000°C, the atmosphere is Ar / H 2 .

[0118] Example 2: Using pine needles as biomass precursors to prepare FeCoNiCuZn high entropy alloy catalysts, the calcination temperature is 600-1000°C, the atmosphere is N 2 / H 2 .

[0119] The difference between the two methods is:

[0120] Different biomass sources (grapefruit peels vs. pine needles).

[0121] Different metal components (quaternary high entropy alloy vs. quinary high entropy alloy).

[0122] Different calcination temperatures and reducing atmospheres were used to optimize the formation and catalytic performance of different high-entropy alloy nanoparticles.

[0123] Example 3: Preparation method of FeCoNiCuMo high entropy alloy catalyst encapsulated by orange peel-derived N and O-containing biochar

[0124] 1. Biomass pretreatment (S1)

[0125] Select fresh grapefruit peel, remove the skin with a knife, and then wash it three times with distilled water.

[0126] Place the cleaned grapefruit peel in an oven at 60-100°C and dry for 8-12 hours until it is completely dehydrated.

[0127] The dried grapefruit peel was crushed into powder using a grinder and passed through an 80-mesh sieve to obtain a uniform biomass precursor powder.

[0128] 2. Preparation of high entropy alloy precursor solution (S2)

[0129] Prepare metal precursor solution and mix Fe(NO 3 ) 2 9H 2 O,Co(NO 3 ) 2 6H 2 O,Ni(NO 3 ) 2 6H2 O, Cu(NO 3 ) 2 ·3H 2 O,H 24 Mo 7 N 6 O 24 ·4H 2 O was weighed in an appropriate amount according to an equimolar ratio and dissolved in 40.0 mL of deionized water.

[0130] Ultrasonic stirring was performed at 25° C. for 30 min to uniformly disperse the solution and completely dissolve the solution to obtain a high entropy alloy precursor solution.

[0131] 3. Impregnation and drying (S3)

[0132] Take 3-6 g of biomass powder (orange peel powder) and put it into a beaker, add the high entropy alloy precursor solution, keep stirring at room temperature for 12 hours, so that the metal ions can be fully impregnated into the biomass.

[0133] The impregnated biomass powder was taken out and dried in an oven at 100°C for 6 h to ensure complete removal of moisture.

[0134] 4. Calcination and alloying (S4)

[0135] Ar / H2 was introduced into the tube furnace. 2 The dried sample was heated to 600-1000°C at a heating rate of 5°C / min and calcined for 1.5-2.5h.

[0136] During the calcination process, metal ions are reduced and react with the carbon element in the biochar to form nanoscale high-entropy alloy particles, which are encapsulated in the biochar carrier.

[0137] The mixture was naturally cooled to room temperature, and the catalyst powder was taken out to obtain the orange peel-derived N and O-containing biochar-encapsulated FeCoNiCu high entropy alloy catalyst.

[0138] 5. Product Characterization

[0139] X-ray diffraction (XRD) was used to analyze the alloy crystal structure.

[0140] The size and distribution of the nanoparticles were observed by transmission electron microscopy (TEM).

[0141] X-ray photoelectron spectroscopy (XPS) was used to analyze the element content and chemical state on the catalyst surface.

[0142] The above embodiments provide methods for preparing high entropy alloy catalysts from different biomass raw materials, and characterize and test them respectively, which can be used as a basis for industrial application or scientific research.

[0143] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a biomass-derived high entropy alloy catalyst encapsulated with N and O biochar, characterized in that: The method comprises the following steps: S1: providing a biomass raw material and pre-treating it, wherein the pre-treating step comprises: using a cutter to remove the outer thick skin and impurities of the biomass material (such as grapefruit peel), washing it with distilled water for multiple times, drying it at 60-100° C. for 8-12 hours, and then grinding the dried biomass into a uniform powder using a pulverizer to ensure that the impurity content is low and the N and O functional groups are retained in the subsequent carbonization process; S2: preparing a high entropy alloy precursor solution, characterized in that Fe(NO3)2·9H2O, Co(NO3)2·6H2O, Ni(NO3)2·6H2O, and Cu(NO3)2·3H2O are dissolved in a specified volume (e.g., 40.0 mL) of water in an equimolar ratio, stirred to form a uniform solution, and the concentration of the solution is adjusted to ensure that the metal ions are fully present; S3: The biomass powder obtained in step S1 is appropriately carbonized under an inert atmosphere to prepare biochar containing N and O functional groups, and then the biochar is fully impregnated with the high entropy alloy precursor solution prepared in step S2 to ensure that the biochar fully adsorbs the metal ions, and then the impregnated mixture is dried to remove the solvent and fix the precursor in the biochar pores; S4: The dried sample obtained in step S3 is heated to 600-1000°C in an Ar / H2 mixed atmosphere at a heating rate of 5°C / min, and kept at this temperature for 1.5-2.5 hours, so that the metal ions generate high entropy alloy nanoparticles in the reduction reaction, and under the encapsulation effect of the biochar, a uniformly dispersed high entropy alloy catalyst with controlled particle size is formed.

2. The method according to claim 1, characterized in that: The S1 specifically includes: Grapefruit peel was used as the biomass raw material, and the peel was removed and then washed with distilled water; The washed grapefruit peel was dried at 80°C for 10 h; The dried grapefruit peel was crushed with a grinder to obtain biomass powder.

3. The method according to claim 1, characterized in that The S2 specifically includes: Fe(NO3)2·9H2O, Co(NO3)2·6H2O, Ni(NO3)2·6H2O and Cu(NO3)2·3H2O were dissolved in water in equal molar ratios; The solution was ultrasonically stirred for 30 min to obtain a uniform high entropy alloy precursor solution.

4. The method according to claim 1, characterized in that The S3 specifically includes: The biochar powder was immersed in the high entropy alloy precursor solution and stirred for 12 h; The resulting solution was then placed in a forced air drying oven and dried at 100° C. for 6 h.

5. The method according to claim 1, characterized in that The S4 specifically includes: The precursor powder obtained in step S3 is placed in a tube furnace, heated to 800°C at a heating rate of 5°C / min in an Ar / H2 atmosphere and maintained for 2 hours, and then naturally cooled to room temperature to obtain a high entropy alloy catalyst.

6. The method according to claim 1, characterized in that In the S4 process, metal ions are reduced during the calcination stage and combined with carbon elements in the biochar to form nanoscale high entropy alloy particles that are encapsulated by the biochar shell.

7. A biomass-derived high entropy alloy catalyst encapsulated with N and O biochar, characterized in that: The catalyst includes: Biomass-derived N and O-containing biochar, which serves as a carrier to coat the catalyst and provide N and O element modification; High entropy alloy nanoparticles, wherein the high entropy alloy is composed of multiple metal elements such as Fe, Co, Ni, Cu, etc., and is generated by a thermal reduction reaction; The high entropy alloy nanoparticles are uniformly dispersed inside the biochar and encapsulated by the biochar shell, wherein the pore structure of the biochar is regulated by high-temperature calcination to enhance the stability and durability of the catalyst.

8. The biomass-derived N,O-containing biochar-encapsulated high entropy alloy catalyst according to claim 7, characterized in that: The preparation method of the high entropy alloy nanoparticles comprises: The biomass material (grapefruit peel) is dried and crushed to form a precursor; Fe(NO3)2·9H2O, Co(NO3)2·6H2O, Ni(NO3)2·6H2O and Cu(NO3)2·3H2O were dissolved in water in an equal molar ratio to prepare a high entropy alloy precursor solution; The N and O-containing biochar is immersed in a high entropy alloy precursor solution to fully adsorb metal ions and then dried; The precursor powder was calcined at high temperature for 2 h in an Ar / H2 atmosphere to reduce the metal ions to form high-entropy alloy nanoparticles, which were then in-situ coated with biochar.

9. The biomass-derived N,O-containing biochar encapsulated high entropy alloy catalyst according to claim 7, characterized in that: The catalyst is used in the field of catalytic reactions, including but not limited to: Electrocatalytic hydrogen evolution reaction (HER); Oxygen reduction reaction (ORR); Small organic molecules catalyze oxidation / reduction reactions; Pollutant degradation or environmental catalysis.

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