High-entropy alloy catalyst for producing formic acid based on biomass as well as preparation method and application of high-entropy alloy catalyst

Abstract

The invention discloses a high-entropy alloy catalyst for producing formic acid based on biomass and a preparation method and application thereof, and belongs to the technical field of catalytic materials, the general formula of the high-entropy alloy catalyst is MnFeCoNiCu, and the high-entropy alloy catalyst has a face-centered cubic crystal structure. The preparation method of the high-entropy alloy catalyst comprises the following steps: loading a thiourea solution on a substrate, drying, and carrying out first Joule heating treatment; and loading a mixed solution containing a manganese salt, an iron salt, a cobalt salt, a nickel salt and a copper salt on the substrate subjected to the first Joule heating treatment, drying, and carrying out second Joule heating treatment to obtain the high-entropy alloy catalyst. The high-entropy alloy catalyst shows high catalytic activity and formic acid selectivity on various biomass sugars such as glucose, arabinose, xylose and fructose, also has excellent catalytic performance on waste straw hydrolysate, and can efficiently promote formic acid generation.

Description

Technical Field

[0001] This invention relates to the field of catalytic materials technology, specifically a high-entropy alloy catalyst based on biomass formic acid production, its preparation method, and its application. Background Technology

[0002] The continued consumption of fossil fuels has triggered severe environmental challenges and an energy crisis. Against this backdrop, biomass, as the world's fourth largest energy source after coal, oil, and natural gas, represents an extremely abundant "zero-carbon" resource reserve. Through catalytic conversion, biomass-derived platform compounds can be efficiently transformed into various high-value-added products. Formic acid, a non-corrosive and non-toxic chemical reagent, is highly versatile and can be widely used in the chemical and energy fields. As a convenient source of carbon monoxide or hydrogen, formic acid, with its strong reducing properties, can be used as a hydrogen donor for in-situ hydrogen production. Furthermore, formic acid contains only C, H, and O elements, giving it an advantage over inorganic acids in biomass pretreatment because it does not produce inorganic residues. Simultaneously, formic acid is also a key platform chemical for the synthesis of textiles, pharmaceuticals, leather, and elastomers.

[0003] However, the efficient conversion of biomass into formic acid typically involves the selective breaking of multiple C-C bonds, resulting in a complex reaction pathway and low formic acid yield. Single or bimetallic catalysts suffer from high cost, limited active sites, and poor selectivity and stability. Therefore, developing catalysts that combine low cost, high activity, high selectivity, and excellent durability is a core challenge for achieving the high-value utilization of biomass resources.

[0004] In recent years, high-entropy catalysts have demonstrated outstanding catalytic performance due to their unique high-entropy effect, lattice distortion effect, slow diffusion effect, and cocktail synergistic effect, providing new opportunities for the high-value utilization of biomass to produce formic acid. Therefore, utilizing high-entropy alloy catalysts to promote the high-value utilization of biomass to produce formic acid is a promising strategy. Summary of the Invention

[0005] The purpose of this invention is to provide a high-entropy alloy catalyst for the production of formic acid from biomass, its preparation method, and its application, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A high-entropy alloy catalyst for the production of formic acid from biomass, with the general formula MnFeCoNiCu, has a face-centered cubic crystal structure.

[0007] Another object of the present invention is to provide a method for preparing the above-mentioned high-entropy alloy catalyst based on biomass formic acid production, comprising the following steps: Thiourea solution was loaded onto a substrate, dried, and then subjected to a first Joule heating treatment. A mixed solution containing manganese, iron, cobalt, nickel, and copper salts was loaded onto a substrate that had undergone a first Joule heating treatment. After drying, a second Joule heating treatment was performed to obtain a high-entropy alloy catalyst.

[0008] Furthermore, the substrate is pretreated carbon cloth.

[0009] Furthermore, the pretreatment method for the carbon cloth is as follows: the carbon cloth is soaked in acetone and washed with ultrapure water.

[0010] Furthermore, the thiourea solution is prepared by dissolving thiourea in anhydrous ethanol, and the concentration of thiourea is 0.05-0.15 mol / L.

[0011] Furthermore, the method for the first Joule heating treatment is as follows: heating to 1400-1600K in a vacuum environment and holding at that temperature for 0.3-0.8s.

[0012] Furthermore, the manganese salt, iron salt, cobalt salt, nickel salt, and copper salt are all chloride salts, and their molar concentrations are all equal.

[0013] Furthermore, the method for the second Joule heating treatment is as follows: heating to 900-1500K in a vacuum environment and holding at that temperature for 0.0-1.0s.

[0014] Another objective of this invention is to provide the application of the above-mentioned high-entropy alloy catalyst based on biomass formic acid production in the electrocatalytic conversion of biomass to formic acid.

[0015] Furthermore, the biomass includes straw waste and biomass sugars; the biomass sugars include glucose, arabinose, xylose, and fructose.

[0016] This invention provides a high-entropy alloy catalyst for formic acid production from biomass. This catalyst exhibits high catalytic activity and formic acid selectivity for various biomass sugars, including glucose, arabinose, xylose, and fructose. It also demonstrates excellent catalytic performance on waste straw hydrolysate, efficiently promoting formic acid formation. Research indicates that utilizing high-entropy alloy catalysts to promote the high-value conversion of biomass resources into formic acid is a promising technology. Attached Figure Description

[0017] Figure 1 The X-ray diffraction pattern of the high-entropy alloy catalyst MnFeCoNiCu prepared in Example 1 is shown below. Figure 2 This is a scanning electron microscope image of the high-entropy alloy catalyst MnFeCoNiCu prepared in Example 1; Figure 3The image shows the catalytic effect of the high-entropy alloy catalyst prepared in Example 2 at different termination temperatures of 1000K, 1200K, and 1400K. Figure 4 The main products of straw hydrolysis in Example 3 are shown. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] In one embodiment of the present invention, a high-entropy alloy catalyst based on biomass formic acid production is provided, which has the general formula MnFeCoNiCu and has a face-centered cubic crystal structure.

[0020] Specifically, the preparation method of this high-entropy alloy catalyst includes the following steps: S1. Soak the carbon cloth in acetone and wash it with ultrapure water to remove impurities, and obtain the pretreated carbon cloth as a substrate. S2. Dissolve thiourea in anhydrous ethanol to prepare a thiourea solution with a concentration of 0.05-0.15 mol / L. Load the thiourea solution onto the substrate (e.g., by dropping, coating, etc.) and then place it in a vacuum oven at 50-70℃ to dry it to ensure complete removal of moisture. Subsequently, under vacuum, rapidly raise the temperature to 1400-1600K and hold it for 0.3-0.8s to perform the first Joule heating treatment. S3. A mixed solution containing manganese salt, iron salt, cobalt salt, nickel salt, and copper salt is loaded (e.g., dropped, coated) onto a substrate that has undergone the first Joule heating treatment. Then, it is placed in a vacuum oven at 50-70°C for drying to ensure complete removal of moisture. Subsequently, under vacuum, the temperature is rapidly raised to 900-1500K (preferably 1300-1500K) and held for 0.0-1.0s to perform a second Joule heating treatment, thereby obtaining a high-entropy alloy catalyst.

[0021] In practical applications, manganese, iron, cobalt, nickel, and copper salts can all be chlorides of the corresponding metals, and the molar concentrations are all equal. Specifically, equimolar amounts of manganese, iron, cobalt, nickel, and copper salts can be dissolved in a mixed solvent of water and anhydrous ethanol (1:1, v / v) to prepare a solution with a concentration of 0.1-0.02 mol / L for each metal salt. The thiourea solution and the metal salt mixture should be sonicated for at least 30 minutes to ensure thorough mixing.

[0022] The high-entropy alloy catalyst prepared above can be directly used in the electrocatalytic conversion of biomass to formic acid, wherein the biomass includes straw waste and biomass sugars, etc.; the biomass sugars include, but are not limited to, glucose, arabinose, xylose and fructose.

[0023] Compared with the prior art, the high-entropy alloy catalyst provided in this embodiment of the invention has the following advantages: (1) The five elements Mn, Fe, Co, Ni and Cu are mixed to form a face-centered cubic structure, which enhances the synergistic effect between metals and thus improves the activity of the catalyst. (2) The electronic structure regulation of different metal elements in the high-entropy alloy generates multiple active sites, which further improves the selectivity and yield of formic acid. (3) The high-entropy alloy catalyst exhibits excellent stability and its performance did not decay after 20 consecutive cycles of testing. (4) The preparation process is simple and efficient, which is conducive to large-scale production.

[0024] Unless otherwise specified, all raw materials used in the following embodiments are commercially available products and can be purchased through commercial channels. The invention will be described in detail below through specific embodiments in practical applications.

[0025] Example 1: This example provides a high-entropy alloy catalyst for the production of formic acid from biomass, which has the general formula MnFeCoNiCu and a face-centered cubic crystal structure.

[0026] Specifically, the preparation method of this high-entropy alloy catalyst includes the following steps: S1. Soak the carbon cloth in acetone for 30 minutes and wash it with ultrapure water to remove impurities, and obtain the pretreated carbon cloth as a substrate. S2. Dissolve 1.903g of thiourea in 250mL of anhydrous ethanol, sonicate for 30min, and prepare a 0.1mol / L thiourea solution. Add the thiourea solution evenly to the above substrate, and then dry it in a vacuum oven at 60℃ for 6h. Then place it in a Joule heating instrument, and rapidly raise the temperature to 1500K (the termination temperature) under vacuum and hold for 0.5s to perform the first Joule heating treatment. S3. Dissolve MnCl2·4H2O (1.9791g), FeCl3·6H2O (2.7030g), CoCl2 (1.2984g), NiCl2 (1.2960g), and CuCl2 (1.3445g) in 50mL of deionized water and 50mL of anhydrous ethanol, and sonicate for 30min to prepare an equimolar metal salt mixed solution. Add this metal salt mixed solution uniformly dropwise onto the substrate that has undergone the first Joule heating treatment, and then dry it in a vacuum oven at 60℃ for 6h. Subsequently, place it in a Joule heating apparatus, and under vacuum, rapidly raise the temperature to 1400K (the termination temperature) and hold for 0.5s to perform a second Joule heating treatment, thereby obtaining the high-entropy alloy catalyst MnFeCoNiCu.

[0027] The structure of the high-entropy alloy catalyst MnFeCoNiCu prepared above was characterized, and the results are as follows: Figure 1 and Figure 2 As shown. Figure 1 The X-ray diffraction pattern of the high-entropy alloy catalyst MnFeCoNiCu is shown. The characteristic peak at 26.0° is attributed to the carbon cloth substrate. The diffraction peaks at 43.7°, 51.0° and 75.3° can be indexed as the (111), (200) and (220) crystal planes of the face-centered cubic crystal structure, respectively, confirming the successful formation of the target high-entropy alloy phase. Figure 2 Scanning electron microscopy images show that the high-entropy alloy catalyst MnFeCoNiCu is uniformly distributed on the carbon cloth surface, which is conducive to exposing abundant active sites and lays the foundation for subsequent improvement of catalytic performance.

[0028] Comparative Example 1: Compared with Example 1, the only difference is that the solvent of the metal salt mixed solution is different. In this example, the solvent of the metal salt mixed solution is anhydrous ethanol.

[0029] Comparative Example 2: Compared with Example 1, the only difference is that the solvent of the metal salt mixed solution is different. In this example, the solvent of the metal salt mixed solution is deionized water.

[0030] Comparative Example 3: Compared with Example 1, the only difference is the concentration of the metal salt mixed solution. In this example, the concentration of each metal in the metal salt mixed solution is 0.02 mol / L.

[0031] Comparative Example 4: Compared with Example 1, the only difference is that the termination temperature of the second Joule heating is different. In this example, the termination temperature is 1000K.

[0032] Comparative Example 5: Compared with Example 1, the only difference is that the termination temperature of the second Joule heating is different. In this example, the termination temperature is 1200K.

[0033] Comparative Example 6: Compared with Example 1, the only difference is that the holding time for the second Joule heating is different. In this example, the holding time is 0 seconds.

[0034] Comparative Example 7: Compared with Example 1, the only difference is that the holding time for the second Joule heating is different. In this example, the holding time is 1 second.

[0035] Comparative Example 8: Compared with Example 1, the only difference is that the second Joule heating method is replaced by a high-temperature calcination method. Specifically, in this example, a tube furnace is used to heat to 1400K at a heating rate of 5°C / min, and then held at that temperature for 30min.

[0036] Comparative Example 9: Compared with Example 1, the only difference is that the molar ratio of the five metals is different. In this example, Mn:Fe:Co:Ni:Cu = 2:1:1:1:1.

[0037] Comparative Example 10: Compared with Example 1, the only difference is that the molar ratio of the five metals is different. In this example, Mn:Fe:Co:Ni:Cu = 1:2:1:1:1.

[0038] Comparative Example 11: Compared with Example 1, the only difference is that the molar ratio of the five metals is different. In this example, Mn:Fe:Co:Ni:Cu = 1:1:2:1:1.

[0039] Comparative Example 12: Compared with Example 1, the only difference is that the molar ratio of the five metals is different. In this example, Mn:Fe:Co:Ni:Cu = 1:1:1:2:1.

[0040] Comparative Example 13: Compared with Example 1, the only difference is that the molar ratio of the five metals is different. In this example, Mn:Fe:Co:Ni:Cu = 1:1:1:1:2.

[0041] Comparative Example 14: Compared with Example 1, the only difference is that the five-metal salt is different. In this example, Mg salt is used instead of Mn salt.

[0042] Comparative Example 15: Compared with Example 1, the only difference is that the five metal salts are different. In this example, La salt is used instead of Mn salt.

[0043] Comparative Example 16: Compared with Example 1, the only difference is that the five metal salts are different. In this example, Pt salt is used instead of Mn salt.

[0044] Example 2: This example is an experiment evaluating the effect of termination temperature on the electrocatalytic performance of the catalyst in the production of formic acid from glucose, as detailed below: The high-entropy alloy catalysts prepared in Example 1, Comparative Example 4, and Comparative Example 5 were applied to the glucose-to-formic acid reaction to evaluate their catalytic performance. The specific operation process is as follows: The high-entropy alloy catalyst prepared above was used as a self-supporting working electrode. All electrochemical tests were performed at room temperature using a standard three-electrode system on a CHI660F electrochemical workstation, with a graphite electrode as the counter electrode and an Hg / HgO electrode as the reference electrode. The electrolyte used for the glucose oxidation reaction consisted of KOH and glucose. All potential values ​​were converted to the reversible hydrogen electrode (RHE) scale using the following formula: E(vs.RHE) = E(vs.Hg / HgO) + 0.059 × pH + 0.098 V.

[0045] During the experiment, the test solution was added to a centrifuge tube containing dilute sulfuric acid and mixed thoroughly. High-performance liquid chromatography (HPLC) was used to analyze the reaction solution (column temperature set at 50℃, mobile phase at 0.05 mol / L sulfuric acid, flow rate at 0.5 mL / min). A calibration curve was established using standards for quantitative analysis to accurately calculate the product concentration. The glucose conversion rate, formic acid selectivity, and formic acid yield were calculated using the following formula:

[0046]

[0047]

[0048] The performance test results of the catalysts are shown in Table 1.

[0049] Table 1. Evaluation results of catalysts for the electrocatalytic reaction of glucose at different termination temperatures.

[0050] The performance of the high-entropy alloy catalyst MnFeCoNiCu at different termination temperatures in the glucose-to-formic acid reaction was compared. As shown in Table 1, at a termination temperature of 1400 K, the glucose conversion reached 100%, and the formic acid selectivity and yield were both above 92%, indicating that the catalyst possesses excellent activity and selectivity. In contrast, the performance of catalysts at other termination temperatures decreased significantly under the same reaction conditions.

[0051] To investigate the effect of pyrolysis temperature on catalyst performance, high-entropy alloy catalysts prepared at termination temperatures of 1000 K, 1200 K, and 1400 K were named MnFeCoNiCu-1000K, MnFeCoNiCu-1200K, and MnFeCoNiCu-1400K, respectively. Their catalytic performance was compared... Figure 3 As shown. Figure 3The trends of conversion rate and yield over time in the conversion of glucose to formic acid catalyzed by three catalysts are presented. At all the same reaction time points, the MnFeCoNiCu-1400K catalyst exhibited the highest glucose conversion rate and formic acid yield. Specifically, this catalyst achieved complete glucose conversion (100% conversion rate) earliest, while the formic acid yield exceeded 90%, demonstrating extremely high reactivity and selectivity. In contrast, the MnFeCoNiCu-1200K catalyst reached its maximum yield relatively late, and its highest yield was less than 80%. Notably, the formic acid yields of both the MnFeCoNiCu-1400K and MnFeCoNiCu-1200K catalysts reached their peak simultaneously. However, subsequently, the yield of the MnFeCoNiCu-1200K catalyst decreased sharply, while the yield of the MnFeCoNiCu-1400K catalyst remained relatively stable. This comparison shows that the MnFeCoNiCu-1400K catalyst, while maintaining high catalytic activity, can effectively suppress the excessive oxidation of formic acid to CO2, thus exhibiting superior stability and product selectivity. These results demonstrate that the high-entropy alloy catalyst prepared in the embodiments of this invention can effectively adjust the synergistic effect between metals by controlling the synthesis conditions, achieving an ideal balance between high conversion rate, high selectivity, and low by-product formation.

[0052] Furthermore, under the same reaction conditions, the catalyst prepared using a tube furnace achieved a glucose conversion of 75.74%, a formic acid selectivity of 48.61%, and a formic acid yield of 36.81% in the electrocatalytic process (i.e., Comparative Example 8). In contrast, the catalyst prepared using Joule heating (i.e., Example 1) achieved a glucose conversion of 100%, a formic acid selectivity of 81.27%, and a formic acid yield of 81.27%, nearly twice that under the tube furnace heating conditions.

[0053] Example 3: This example is an experiment evaluating the effect of elemental ratio and composition on the electrocatalytic performance of the catalyst in the production of formic acid from glucose, as detailed below: The high-entropy alloy catalysts prepared in Example 1 and Comparative Examples 9-16 were applied to the glucose-to-formic acid reaction for catalytic performance evaluation. The performance testing methods were the same as those in Example 2, and the catalyst performance evaluation results are shown in Table 2 below: Table 2 Evaluation results of catalysts with different elemental ratios and compositions on the electrocatalytic reaction of glucose.

[0054] Table 2 shows the effects of different element ratios and compositions on the electrocatalytic performance of glucose. The results indicate that the element ratio has a significant impact on performance: in the pentagonal high-entropy alloy (MnFeCoNiCu), increasing the proportion of any one metal (such as Mn2, Fe2, etc.) may maintain a high glucose conversion rate (>90%), but the formic acid selectivity significantly decreases. This suggests that the original equimolar ratio may be the optimal combination for achieving a balance between high activity and high selectivity. Mn plays an irreplaceable role in maintaining catalytic activity and selectivity. Replacing it with other metals (including noble metals) leads to performance degradation (other elements are equally important, but only the results of replacing Mn are shown here). The original equimolar MnFeCoNiCu catalyst exhibits the best overall performance among all comparative samples, verifying that this specific pentagonal high-entropy alloy combination has the best synergistic catalytic effect. Adding, removing, or replacing any single element will disrupt this synergistic effect, leading to a decrease in performance (especially selectivity). The formic acid yield is determined by both conversion and selectivity. Even with high conversion rates (e.g., comparative examples 9-12), low selectivity severely limits the final yield. This highlights the importance of developing catalysts with both high conversion rates and high selectivity in biomass catalytic conversion. In this study, an equimolar ratio of MnFeCoNiCu pentagonal high-entropy alloy exhibited the best catalytic performance. A unique synergistic effect may exist among the five metals; any alteration to their composition or ratio leads to a decrease in catalytic performance (especially formic acid selectivity).

[0055] Example 4: This example investigates the evaluation of the formic acid production performance of the high-entropy alloy catalyst MnFeCoNiCu on different biomass sugars and straws, as detailed below: The high-entropy alloy catalyst prepared in Example 1 was used in the reaction of straw and various biomass sugars to produce formic acid to evaluate its catalytic performance. The specific experimental steps are as follows: First, 5g of crushed straw was mixed with 75mL of 72wt% sulfuric acid and stirred at room temperature for 2 hours. Then, the resulting solution was transferred to a round-bottom flask, and 900mL of water was added to dilute the sulfuric acid concentration to 3wt%. Next, the mixture was refluxed at 100°C for 12 hours (with magnetic stirring). After the reaction was complete, lignin was removed by vacuum filtration. The pH of the solution was adjusted to neutral with barium hydroxide (Ba(OH)₂), and then KOH solution was added to prepare a reaction solution suitable for electrocatalytic reactions.

[0056] Four biomass sugars—glucose, arabinose, xylose, and fructose—were selected for the experiment. The electrolyte consisted of KOH and the corresponding biomass sugar.

[0057] The high-entropy alloy catalyst prepared in Example 1 was used as the working electrode. All electrochemical tests were performed at room temperature using a CHI660F electrochemical workstation and a standard three-electrode system, with a graphite electrode as the counter electrode and an Hg / HgO electrode as the reference electrode. All potentials were converted to the reversible hydrogen electrode (RHE) scale using the following formula: E(vs.RHE) = E(vs.Hg / HgO) + 0.059 × pH + 0.098 V.

[0058] During the reaction, samples were taken at intervals and added to centrifuge tubes containing dilute sulfuric acid and mixed thoroughly. High-performance liquid chromatography (HPLC) was used to analyze the samples (column temperature 50℃, mobile phase 0.05 mol / L sulfuric acid, flow rate 0.5 mL / min). A calibration curve was established using standards for quantification, thereby accurately calculating the product concentration. Substrate conversion, formic acid selectivity, and formic acid yield were calculated using the following formula:

[0059]

[0060]

[0061] The performance of the high-entropy alloy catalyst MnFeCoNiCu on different substrates is shown in Table 3.

[0062] Table 3 Evaluation results of high-entropy alloy catalysts MnFeCoNiCu for electrocatalytic reactions of different substrates

[0063] Table 3 examines the performance differences of the prepared catalysts in the electrocatalytic conversion of glucose, arabinose, xylose, and fructose to formic acid. The results show that the high-entropy alloy catalyst MnFeCoNiCu exhibits near-complete conversion of aldose substrates (glucose, arabinose, and xylose), with conversion rates approaching 100%. The corresponding formic acid selectivity and yield also remain at a high level of 85%-95%, and the performance differences among the three aldoses are minimal. In contrast, the catalyst shows lower catalytic performance for fructose, but the formic acid yield still remains close to 80%. This indicates that the catalyst possesses excellent and stable directional conversion capabilities for biomass sugars. Figure 4This paper presents the catalytic performance evaluation of the high-entropy alloy catalyst MnFeCoNiCu using straw hydrolysate as raw material, further verifying its applicability to real biomass substrates. Compositional analysis of the straw hydrolysate shows that it mainly contains three biomass sugars: glucose, xylose, and arabinose, with glucose being the most abundant, followed by xylose, and arabinose the least abundant. In this mixed sugar system, the catalyst achieved 100% conversion of the three sugars, with a final formic acid yield of approximately 90%, comparable to the yield level of the pure aldose system. This result confirms that the catalyst maintains high conversion efficiency and product selectivity even in complex real biomass hydrolysates, providing strong support for its industrial application in the targeted preparation of formic acid from agricultural and forestry waste such as straw. These results fully demonstrate the application potential of the high-entropy alloy catalyst MnFeCoNiCu prepared in this invention for the high-value utilization of biomass waste, providing experimental basis for the subsequent construction of a complete technical route for formic acid production from straw.

[0064] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification.

Claims

1. A high-entropy alloy catalyst for formic acid production based on biomass, characterized in that, The high-entropy alloy catalyst has the general formula MnFeCoNiCu and has a face-centered cubic crystal structure.

2. A method for preparing a high-entropy alloy catalyst based on biomass formic acid production as described in claim 1, characterized in that, Includes the following steps: Thiourea solution was loaded onto a substrate, dried, and then subjected to a first Joule heating treatment. A mixed solution containing manganese, iron, cobalt, nickel, and copper salts was loaded onto a substrate that had undergone a first Joule heating treatment. After drying, a second Joule heating treatment was performed to obtain a high-entropy alloy catalyst.

3. The method for preparing a high-entropy alloy catalyst based on biomass formic acid production according to claim 2, characterized in that, The substrate is pretreated carbon cloth.

4. The method for preparing a high-entropy alloy catalyst based on biomass formic acid production according to claim 3, characterized in that, The pretreatment method for the carbon cloth is as follows: soak the carbon cloth in acetone and wash it with ultrapure water.

5. The method for preparing a high-entropy alloy catalyst for formic acid production based on biomass according to claim 2, characterized in that, The thiourea solution is prepared by dissolving thiourea in anhydrous ethanol, and the concentration of thiourea is 0.05-0.15 mol / L.

6. The method for preparing a high-entropy alloy catalyst based on biomass formic acid production according to claim 2, characterized in that, The method for the first Joule heating treatment is as follows: under vacuum, heat to 1400-1600K and hold for 0.3-0.8s.

7. The method for preparing a high-entropy alloy catalyst based on biomass formic acid production according to claim 2, characterized in that, The manganese, iron, cobalt, nickel, and copper salts are all chloride salts, and all have the same molar concentration.

8. The method for preparing a high-entropy alloy catalyst based on biomass formic acid production according to claim 2, characterized in that, The method for the second Joule heating treatment is as follows: heat to 900-1500K in a vacuum environment and hold for 0.0-1.0s.

9. The application of a high-entropy alloy catalyst based on biomass formic acid production as described in claim 1 in the electrocatalytic conversion of biomass to formic acid.

10. The application according to claim 9, characterized in that, The biomass includes straw waste and biomass sugars; the biomass sugars include glucose, arabinose, xylose, and fructose.

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