Universal method for synthesizing CuCoAg-based high-entropy solid solution catalyst based on Joule heat and application

Abstract

The invention discloses a universal method for synthesizing a CuCoAg-based high-entropy solid solution catalyst based on Joule heat and application of the CuCoAg-based high-entropy solid solution catalyst based on Joule heat, metal combinations are screened based on high-entropy solid solution forming conditions, the key point is that high-entropy solid solution synthesized through an ultrafast Joule heat two-step method has outstanding universality, and the CuCoAg-based high-entropy solid solution catalyst can be successfully applied to various different metal combinations; the target high-entropy solid solution catalyst is efficiently synthesized. The method has the remarkable advantages of simplicity and convenience in operation, low cost, environment friendliness and the like. The prepared catalyst shows excellent performance in ammonia preparation through reduction of electro-catalysis nitrate radicals, the optimal sample Faraday efficiency is as high as 98.89%, and the ammonia yield is as high as 323.75 mu mol / h / cm < 2 >. According to the invention, efficient preparation of the multi-element high-entropy solid solution electrocatalyst is realized, and an empirical case is provided for green ammonia production through nitrate radical reduction.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of electrocatalytic nitrate-to-ammonia catalysts, and specifically relates to a universal method for synthesizing a CuCoAg-based high-entropy solid solution catalyst based on Joule heat and its application. Background Art

[0002] Ammonia (NH3), a cornerstone of modern industry, is not only a core raw material for fertilizer and chemical synthesis, but also a highly promising carbon-free energy carrier and hydrogen storage and transportation medium. With the advancement of my country's "Special Action Plan for Energy Conservation and Carbon Reduction in the Synthetic Ammonia Industry," the development of green, low-carbon synthetic ammonia technologies has become a key path to achieving the "dual carbon" goals. The current mainstream Haber-Bosch Process relies on fossil fuels to synthesize ammonia using nitrogen (N2) and hydrogen (H2) at high temperature and high pressure. This inherent bottleneck, such as high energy consumption (accounting for 1%-2% of global energy consumption) and high carbon emissions (1.9 tons of CO2 per ton of ammonia), makes it difficult to meet the needs of the clean energy transition. Therefore, the development of new electrochemical ammonia synthesis technologies that can be coupled with renewable energy is imperative.

[0003] In recent years, electrocatalytic nitrogen reduction (NRR) and electrocatalytic nitrate reduction (NO3RR) ammonia production technologies have attracted much attention. Among them, NRR uses H2O and N2 as raw materials, and theoretically can achieve zero-carbon ammonia production. However, due to the extremely high chemical inertness of nitrogen molecules (N≡N bond energy 941kJ / mol) and competitive hydrogen evolution reaction (HER), its ammonia yield and Faraday efficiency are still far below industrial requirements. In contrast, nitrate reduction (NO3RR) shows significant advantages: on the one hand, nitrate (NO3 - ) is widely present in agricultural runoff and industrial wastewater. It is not only an environmental pollutant, but also an efficient nitrogen source (N=O bond energy 204kJ / mol, theoretical reaction potential 0.69Vvs.RHE); on the other hand, NO3RR converts nitrate pollutants into high-value-added ammonia products through electrochemical reduction, achieving the dual benefits of pollution control and resource utilization, which is in line with the concept of circular economy. Therefore, it is necessary to design and construct ideal electrocatalysts and deeply understand the nitrate reduction mechanism to effectively manipulate NO3 – Reducing the pathway to obtain the desired product is a very meaningful task.

[0004] Copper exhibits excellent catalytic activity in NO3RR due to its d-orbital energy level being very well matched to the lowest unoccupied molecular orbital energy level of NO3-. However, the intrinsic active site density of elemental copper catalysts is insufficient, resulting in slow reaction kinetics. To overcome this bottleneck, alloying strategies have been widely adopted. By synergistically regulating the electronic structure and surface adsorption behavior of active sites through multi-metal components, the efficiency of nitrate activation and ammonia synthesis can be significantly enhanced. High-entropy alloy catalytic materials can combine metals with different adsorption energy characteristics, achieving high miscibility of more than a dozen different metals. The high-entropy effect overcomes the disadvantage of uneven distribution of surface principal elements caused by local segregation. For example, the patent document CN202410916297.X discloses a method for preparing FeCoNiAlMn high-entropy alloy nanoparticles loaded with CF and multifunctional composite materials. The specific preparation process is: immersing a continuous CF filament bundle in a surfactant dispersion solution, and pulling the CF filament bundle to a drying device for drying treatment under an inert atmosphere; continuing to pull the CF filament bundle into a metal salt precursor solution, and pulling the CF filament bundle to a drying device for drying treatment under an inert atmosphere; wherein the metal salt precursor solution is a mixed salt solution composed of soluble Fe salt, Co salt, Ni salt, Al salt, and Mn salt in a molar ratio of Fe:Co:Ni:Al:Mn=1.3:1:1:1.8:2.5; pulling the CF filament bundle to a microwave generator for microwave carbon thermal shock treatment for 3 to 7 seconds under an inert atmosphere. The technical solution of this patent document can flexibly and quickly adjust the magneto-thermal properties of CF and its composite materials, so that the CF composite materials have excellent electromagnetic absorption and thermal conductivity. However, this patent does not reflect the universal preparation method of CuCoAg-based high-entropy solid solution catalysts, nor does it contain any relevant records on the use of catalysts for electrocatalytic nitrate production of ammonia.

[0005] Joule heating, as an efficient multi-element alloy preparation technology, stands out due to its ultra-fast heating and cooling rates and precise temperature control capabilities. Based on this, the present invention, based on the previous research on CuCoAg ternary alloys, screened out 10 five-element metal combinations and 3 six-element metal combinations that meet the conditions through high entropy solid solution conditions. The core advantage of using ultrafast Joule heating technology to construct a multi-site synergistic mechanism is that the two-step Joule heating method is universal and can adapt to different metal combinations, providing a universal approach for the development of efficient electrochemical ammonia synthesis technology. Summary of the Invention

[0006] The technical problem solved by the present invention is to provide a universal method for synthesizing CuCoAg-based high-entropy solid solution catalysts based on Joule heat. This method can achieve the precise construction of a variety of high-entropy solid solutions by changing the type of metal precursor. The synthesized CuCoAg-based high-entropy solid solution catalyst can be used for electrocatalytic nitrate production to ammonia.

[0007] The present invention adopts the following technical solution to solve the above technical problems, a universal method for synthesizing CuCoAg-based high entropy solid solution catalysts based on Joule heat, characterized in that the specific preparation steps are:

[0008] Step S1: Based on the formation conditions of high entropy solid solution, i.e., the maximum atomic radius difference between metal elements is less than 12% and the alloy mixing enthalpy is between -40 and 10 kJ mol -1 Screening qualified five-element metal combinations and six-element metal combinations, wherein the five-element metal combination is CuCoAgAlCr, CuCoAgFeCr, CuCoAgFeMn, CuCoAgNiAl, CuCoAgNiCr, CuCoAgNiMn, CuCoAgAlMn, CuCoAgFeAl, CuCoAgFeNi or CuCoAgCrMn, and the six-element metal combination is CuCoAgAlMnCr, CuCoAgAlMnFe or CuCoAgAlMnNi;

[0009] Step S2: Based on the five-membered metal combination or six-membered metal combination selected in step S1, the corresponding soluble metal salt is prepared into a five-membered metal mixed solution or a six-membered metal mixed solution, i.e., a metal precursor solution, with a total metal atomic molar concentration of 0.2 to 0.4 mol / L, and the carbon paper is hydrophilically treated.

[0010] Step S3: dripping the metal precursor solution obtained in step S2 onto the hydrophilic treated carbon paper, ensuring that the metal precursor solution completely covers the carbon paper, and then placing it under an infrared lamp until the surface of the carbon paper is completely dry to obtain the precursor material;

[0011] Step S4: The precursor material obtained in step S3 is placed in a Joule heating reaction chamber and a hydrogen / argon mixture is continuously introduced. When the mixture is introduced, the vacuum degree in the reaction chamber is maintained at 0.3-0.5 MPa to ensure that there is no air remaining in the reaction chamber to avoid the generation of oxides. Then, a Joule heating reaction is carried out at 1100-1300°C to obtain the target product, a CuCoAg-based high entropy solid solution catalyst. The CuCoAg-based high entropy solid solution catalyst is used for electrocatalytic nitrate production of ammonia.

[0012] More preferably, the specific formula for screening the high entropy solid solution metal combination that meets the conditions in step S1 is as follows:

[0013] Atomic radius:

[0014] Differences in atomic radius:

[0015] Mixing enthalpy:

[0016] Further preferably, the five-component metal mixture in step S2 is a mixed salt solution formed by dissolving the corresponding soluble metal salts in water according to a molar ratio of Cu:Co:Ag:X:Y=2:0.5:0.5:0.5:0.5, wherein X and Y are selected from any two of Al, Fe, Ni, Cr and Mn; the six-component metal mixture is a mixed salt solution formed by dissolving the corresponding soluble metal salts in water according to a molar ratio of Cu:Co:Ag:Al:Mn:Z=2:0.5:0.5:0.5:0.5:0.5, wherein Z is selected from Cr, Fe or Ni.

[0017] Further preferably, the Joule heat reaction temperature in step S3 is 1200°C, and it is divided into two heating temperature rising modes. The first slope mode has a heating time of 10s, a current of 170A, and a voltage of 40V; the second fast mode has a heating time of 1s, a current of 400A, and a voltage of 40V, and the metal is controlled to form nano-alloy particles by short-term temperature rise and fall.

[0018] Further preferably, a universal method for synthesizing a CuCoAg-based high entropy solid solution catalyst based on Joule heat is characterized in that the specific preparation steps are:

[0019] Step S1: Screening and obtaining a CuCoAgAlMnCr hexametallic combination according to the formation conditions of a high entropy solid solution;

[0020] Step S2: Based on the CuCoAgAlMnCr hexametallic combination screened in step S1, a mixed solution of copper nitrate trihydrate, cobalt nitrate hexahydrate, silver nitrate, aluminum nitrate nonahydrate, manganese nitrate tetrahydrate, and chromium nitrate nonahydrate is prepared with a total metal atomic molar concentration of 0.3 mol / L, wherein the molar ratio of copper ion, cobalt ion, silver ion, aluminum ion, manganese ion, and chromium ion is 2:0.5:0.5:0.5:0.5:0.5:0.5, and the solvent is water. After thorough mixing, a metal precursor solution is obtained, and the carbon paper is hydrophilic treated at the same time;

[0021] Step S3: Take out 1 mL of the metal precursor solution obtained in step S2 with a syringe and drop it onto the hydrophilic treated carbon paper, ensuring that the metal precursor solution completely covers the carbon paper. Place it under an infrared lamp until the surface of the carbon paper is completely dry to obtain the precursor material;

[0022] Step S4: The precursor material obtained in step S3 is placed in a Joule heating reaction chamber and a hydrogen / argon mixture is continuously introduced. When the mixture is introduced, the vacuum degree in the reaction chamber is maintained at 0.4 MPa to ensure that no air remains in the reaction chamber to avoid the generation of oxides. Then, a Joule heat reaction is performed at 1200°C to obtain the target product CuCoAgAlMnCr high entropy solid solution catalyst, wherein the Joule heat reaction is divided into two heating temperature rising modes, the first slope mode heating time is 10s, the current is set to 170A, and the voltage is set to 40V; the second fast mode heating time is 1s, the current is set to 400A, and the voltage is set to 40V.

[0023] The application of the CuCoAg-based high entropy solid solution catalyst in the electrocatalytic production of ammonia from nitrate is as follows: the working electrode is a CuCoAg-based high entropy solid solution catalyst fixed on a platinum electrode clip; a saturated calomel electrode is selected as the reference electrode; a platinum electrode is selected as the counter electrode; the electrolyte is a 0.5 mol / L K2SO4+0.1 mol / L KNO3 mixed aqueous solution, and a linear sweep voltammetry test is performed to obtain the LSV polarization curve of the CuCoAg-based high entropy solid solution catalyst, with the scanning range set to -0.6 to -1.6 V (vs. SCE) and the scanning rate being 5 mV / s; a chronoamperometric analysis is performed with 0.5 mol / L A mixed aqueous solution of K2SO4 and 0.1 mol / L KNO3 was used as the test solution. The CuCoAg-based high-entropy solid solution catalyst was tested. Multiple potential points were set, and the reaction time at each potential was 1800 seconds. Indigo blue spectrophotometry was used for product quantitative analysis, and the ammonia yield and Faradaic efficiency were calculated. The CuCoAgAlCr high-entropy solid solution catalyst, as an electrocatalyst, exhibited excellent nitrate transamination activity and stability in nitrate transamination, with a Faradaic efficiency of 95.62% and an ammonia yield of 362.255 μmol h-1. -1 cm -2 The CuCoAgAlMnCr high-entropy solid solution catalyst exhibited good stability as an electrocatalyst during the continuous operation of nitrate to ammonia conversion, with a Faradaic efficiency of 98.89% and an ammonia yield of 323.75 μmol h-1. -1 cm -2 .

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] The present invention proposes to screen out a variety of metal combinations (including five-element and six-element) that can form stable high-entropy solid solutions through the screening conditions of high-entropy solid solutions. The screening conditions are also applicable to other metal combinations other than those of the present invention. At the same time, the ultrafast Joule heat synthesis technology proposed in the present invention has significant process innovation and economic advantages. The metals are fully dissolved and nano-alloy particles are formed through a two-step method. Compared with the traditional nitrate reduction ammonia electrocatalyst preparation process (such as high-temperature pyrolysis and hydrothermal synthesis), this method breaks through the limitations of conventional reaction systems and effectively promotes the alloying process of various metal precursors through a unique non-equilibrium rapid temperature rise and fall thermodynamic control mechanism.

[0026] By precisely controlling the Joule heating process parameters, the present invention successfully prepared carbon fiber-supported CuCoAg-based five- and six-element high-entropy solid solution catalysts. This method exhibits good universality and can be extended to a variety of metal combination systems (including but not limited to the combinations listed in the study). Among them, the prepared CuCoAgAlMnCr high-entropy solid solution catalyst exhibited excellent performance in the electrocatalytic nitrate reduction reaction to ammonia, with a Faradaic efficiency of up to 98.89% and an ammonia yield of up to 323.75 μmol·h -1 cm -2 , and showed good stability during continuous electrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a diagram of metal screening conditions for products C1 to C3 prepared in Example 2;

[0028] Figure 2 Schematic diagram of the temperature rise curves of products C1 to C3 prepared in Example 2;

[0029] Figure 3 This is a scanning electron microscope image of product C2 prepared in Example 2;

[0030] Figure 4 X-ray diffraction patterns of products C1 to C3 prepared in Example 2;

[0031] Figure 5 The linear sweep voltammogram of the nitrate transamination catalyst of products C1 to C3 prepared in Example 2;

[0032] Figure 6 The product C2 prepared in Example 2 shows the Faradaic efficiency and ammonia yield of nitrate to ammonia at different potentials during the NO3RR process;

[0033] Figure 7 The product C3 prepared in Example 3 shows the Faradaic efficiency and ammonia yield of nitrate to ammonia at different potentials during the NO3RR process. DETAILED DESCRIPTION

[0034] The above contents of the present invention are further described in detail below through examples, but this should not be understood as limiting the scope of the above subject matter of the present invention to the following examples. All technologies implemented based on the above contents of the present invention fall within the scope of the present invention.

[0035] Example 1

[0036] Step S1: Screening and obtaining a CuCoAgAlMn five-element metal combination according to the formation conditions of a high entropy solid solution;

[0037] Step S2: Based on the CuCoAgAlMn five-element metal combination screened in step S1, a mixed solution of copper nitrate trihydrate, cobalt nitrate hexahydrate, silver nitrate, aluminum nitrate nonahydrate, and manganese nitrate tetrahydrate with a total metal atomic molar concentration of 0.3 mol / L is prepared, wherein the molar ratio of copper ion, cobalt ion, silver ion, aluminum ion, and manganese ion is 2:0.5:0.5:0.5:0.5, and the solvent is water. After thorough mixing, a metal precursor solution A1 is obtained, and the carbon paper is subjected to a hydrophilic treatment.

[0038] Step S3: Take out 1 mL of the metal precursor solution A1 obtained in step S2 with a syringe and drop it onto the hydrophilic treated carbon paper, ensuring that the metal precursor solution completely covers the carbon paper. Place it under an infrared lamp until the surface of the carbon paper is completely dry to obtain the precursor material B1;

[0039] Step S4: The precursor material B1 obtained in step S3 is placed in a Joule heating chamber (refer to the patent technology previously applied for by this research group: CN202311111434.4, a multifunctional and convenient reaction chamber for electrically triggered Joule heating equipment and its operation method) and continuously introduces a hydrogen / argon mixture. When the mixture is introduced, the vacuum degree in the reaction chamber is maintained at 0.4 MPa to ensure that there is no air residue in the reaction chamber to avoid the production of oxides. Then, a Joule heating reaction is carried out at 1200°C to obtain the target product C1. The Joule heating reaction is divided into two heating and temperature rising modes. The first slope mode has a heating time of 10s, a current of 170A, and a voltage of 40V; the second fast mode has a heating time of 1s, a current of 400A, and a voltage of 40V.

[0040] Example 2

[0041] Step S1: Screening and obtaining a CuCoAgAlCr five-element metal combination according to the formation conditions of a high entropy solid solution;

[0042] Step S2: Based on the CuCoAgAlCr five-element metal combination screened in step S1, a mixed solution of copper nitrate trihydrate, cobalt nitrate hexahydrate, silver nitrate, aluminum nitrate nonahydrate, and chromium nitrate nonahydrate is prepared with a total metal atomic molar concentration of 0.3 mol / L, wherein the molar ratio of copper ion, cobalt ion, silver ion, aluminum ion, and chromium ion is 2:0.5:0.5:0.5:0.5, and the solvent is water. After thorough mixing, a metal precursor solution A2 is obtained, and the carbon paper is subjected to a hydrophilic treatment.

[0043] Step S3: Take out 1 mL of the metal precursor solution A2 obtained in step S2 with a syringe and drop it onto the hydrophilic treated carbon paper, ensuring that the metal precursor solution completely covers the carbon paper. Place it under an infrared lamp until the surface of the carbon paper is completely dry to obtain the precursor material B2;

[0044] Step S4: The precursor material B2 obtained in step S3 is placed in a Joule heating chamber (refer to the patent technology previously applied for by this research group: CN202311111434.4, a multifunctional and convenient reaction chamber for electrically triggered Joule heating equipment and its operation method) and continuously introduces a hydrogen / argon mixture. When the mixture is introduced, the vacuum degree in the reaction chamber is maintained at 0.4 MPa to ensure that there is no air residue in the reaction chamber to avoid the production of oxides. Then, a Joule heating reaction is carried out at 1200°C to obtain the target product C2. The Joule heating reaction is divided into two heating and temperature rising modes. The first slope mode has a heating time of 10s, a current of 170A, and a voltage of 40V; the second fast mode has a heating time of 1s, a current of 400A, and a voltage of 40V.

[0045] Example 3

[0046] Step S1: Screening and obtaining a CuCoAgAlMnCr hexametallic combination according to the formation conditions of a high entropy solid solution;

[0047] Step S2: Based on the CuCoAgAlMnCr hexametallic combination screened in step S1, a mixed solution of copper nitrate trihydrate, cobalt nitrate hexahydrate, silver nitrate, aluminum nitrate nonahydrate, manganese nitrate tetrahydrate, and chromium nitrate nonahydrate is prepared with a total metal atomic molar concentration of 0.3 mol / L, wherein the molar ratio of copper ion, cobalt ion, silver ion, aluminum ion, manganese ion, and chromium ion is 2:0.5:0.5:0.5:0.5:0.5:0.5, and the solvent is water. After thorough mixing, a metal precursor solution A3 is obtained, and the carbon paper is subjected to a hydrophilic treatment.

[0048] Step S3: 1 mL of the metal precursor solution A3 obtained in step S2 was taken out with a syringe and dropped onto the hydrophilic treated carbon paper, ensuring that the metal precursor solution completely covered the carbon paper. The carbon paper was placed under an infrared lamp until the surface of the carbon paper was completely dry to obtain the precursor material B3;

[0049] Step S4: The precursor material B3 obtained in step S3 is placed in a Joule heating chamber (refer to the patent technology previously applied for by this research group: CN202311111434.4, a multifunctional and convenient reaction chamber for electrically triggered Joule heating equipment and its operation method) and continuously introduces a hydrogen / argon mixture. When the mixture is introduced, the vacuum degree in the reaction chamber is maintained at 0.4 MPa to ensure that there is no air residue in the reaction chamber to avoid the production of oxides. Then, a Joule heating reaction is carried out at 1200°C to obtain the target product C3. The Joule heating reaction is divided into two heating and heating modes. The first slope mode has a heating time of 10s, a current of 170A, and a voltage of 40V; the second fast mode has a heating time of 1s, a current of 400A, and a voltage of 40V.

[0050] NO3RR activity testing process: A standard three-electrode system was used. The working electrode consisted of products C1-C3 fixed to platinum electrode holders; a saturated calomel electrode (SCE) was used as the reference electrode; and a platinum electrode was used as the counter electrode. The electrolyte consisted of a 0.5 mol / L K2SO4 + 0.1 mol / L KNO3 aqueous solution. Linear sweep voltammetry (LSV) was performed to obtain LSV polarization curves for products C1-C3, with a scan range of -0.6 to -1.6 V (vs. SCE) and a scan rate of 5 mV / s. Chronoamperometry (CA) was performed using a 0.5 mol / L K2SO4 + 0.1 mol / L KNO3 aqueous solution as the test solution. Products C1-C3 were tested at multiple potential points, with a reaction time of 1800 seconds at each potential. Quantitative analysis of the products was performed using indigo blue spectrophotometry, and ammonia yield and Faradaic efficiency were calculated.

[0051] The product C2 prepared in Example 2 showed excellent nitrate transamination activity and stability as an electrocatalyst in nitrate transamination, with a Faradaic efficiency of 95.62% and an ammonia yield of 362.255 μmol h -1 cm -2 The product C3 prepared in Example 3 had a Faradaic efficiency of 98.89% and an ammonia yield of 323.75 μmol h -1 cm -2 , and the invention shows good stability during continuous operation, indicating that the catalyst has broad practical application prospects in the field of nitrate transamination.

[0052] The above embodiments describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A universal method for synthesizing CuCoAg-based high entropy solid solution catalysts based on Joule heat, characterized in that The specific preparation steps are: Step S1: Based on the formation conditions of high entropy solid solution, i.e., the maximum atomic radius difference between metal elements is less than 12% and the alloy mixing enthalpy is between -40 and 10 kJ mol -1 Screening qualified five-element metal combinations and six-element metal combinations, wherein the five-element metal combination is CuCoAgAlCr, CuCoAgFeCr, CuCoAgFeMn, CuCoAgNiAl, CuCoAgNiCr, CuCoAgNiMn, CuCoAgAlMn, CuCoAgFeAl, CuCoAgFeNi or CuCoAgCrMn, and the six-element metal combination is CuCoAgAlMnCr, CuCoAgAlMnFe or CuCoAgAlMnNi; Step S2: Based on the five-membered metal combination or six-membered metal combination selected in step S1, the corresponding soluble metal salt is prepared into a five-membered metal mixed solution or a six-membered metal mixed solution, i.e., a metal precursor solution, with a total metal atomic molar concentration of 0.2 to 0.4 mol / L, and the carbon paper is hydrophilically treated. Step S3: dripping the metal precursor solution obtained in step S2 onto the hydrophilic treated carbon paper, ensuring that the metal precursor solution completely covers the carbon paper, and then placing it under an infrared lamp until the surface of the carbon paper is completely dry to obtain the precursor material; Step S4: The precursor material obtained in step S3 is placed in a Joule heating reaction chamber and a hydrogen / argon mixture is continuously introduced. When the mixture is introduced, the vacuum degree in the reaction chamber is maintained at 0.3-0.5 MPa to ensure that there is no air remaining in the reaction chamber to avoid the generation of oxides. Then, a Joule heating reaction is carried out at 1100-1300°C to obtain the target product, a CuCoAg-based high entropy solid solution catalyst. The CuCoAg-based high entropy solid solution catalyst is used for electrocatalytic nitrate production of ammonia.

2. A universal method for synthesizing CuCoAg-based high entropy solid solution catalysts based on Joule heat according to claim 1, characterized in that The specific formula for screening the high entropy solid solution metal combination that meets the conditions in step S1 is as follows: Atomic radius: Differences in atomic radius: Mixing enthalpy:

3. The universal method for synthesizing CuCoAg-based high entropy solid solution catalysts based on Joule heat according to claim 1, characterized in that In step S2, the five-component metal mixture is a mixed salt solution formed by dissolving the corresponding soluble metal salts in water according to a molar ratio of Cu:Co:Ag:X:Y=2:0.5:0.5:0.5:0.5, wherein X and Y are selected from any two of Al, Fe, Ni, Cr and Mn; the six-component metal mixture is a mixed salt solution formed by dissolving the corresponding soluble metal salts in water according to a molar ratio of Cu:Co:Ag:Al:Mn:Z=2:0.5:0.5:0.5:0.5:0.5, wherein Z is selected from Cr, Fe or Ni.

4. The universal method for synthesizing CuCoAg-based high entropy solid solution catalysts based on Joule heat according to claim 1, characterized in that In step S3, the Joule heat reaction temperature is 1200°C, and it is divided into two heating temperature rising modes. The first slope mode has a heating time of 10s, a current of 170A, and a voltage of 40V; the second fast mode has a heating time of 1s, a current of 400A, and a voltage of 40V. The metal is controlled to form nano-alloy particles by short-term temperature rise and fall.

5. The universal method for synthesizing CuCoAg-based high entropy solid solution catalysts based on Joule heat according to claim 1, characterized in that The specific preparation steps are: Step S1: Screening and obtaining a CuCoAgAlMnCr hexametallic combination according to the formation conditions of a high entropy solid solution; Step S2: Based on the CuCoAgAlMnCr hexametallic combination screened in step S1, a mixed solution of copper nitrate trihydrate, cobalt nitrate hexahydrate, silver nitrate, aluminum nitrate nonahydrate, manganese nitrate tetrahydrate, and chromium nitrate nonahydrate is prepared with a total metal atomic molar concentration of 0.3 mol / L, wherein the molar ratio of copper ion, cobalt ion, silver ion, aluminum ion, manganese ion, and chromium ion is 2:0.5:0.5:0.5:0.5:0.5:0.5, and the solvent is water. After thorough mixing, a metal precursor solution is obtained, and the carbon paper is hydrophilic treated at the same time; Step S3: Take out 1 mL of the metal precursor solution obtained in step S2 with a syringe and drop it onto the hydrophilic treated carbon paper, ensuring that the metal precursor solution completely covers the carbon paper. Place it under an infrared lamp until the surface of the carbon paper is completely dry to obtain the precursor material; Step S4: The precursor material obtained in step S3 is placed in a Joule heating reaction chamber and a hydrogen / argon mixture is continuously introduced. When the mixture is introduced, the vacuum degree in the reaction chamber is maintained at 0.4 MPa to ensure that no air remains in the reaction chamber to avoid the generation of oxides. Then, a Joule heat reaction is performed at 1200°C to obtain the target product CuCoAgAlMnCr high entropy solid solution catalyst, wherein the Joule heat reaction is divided into two heating temperature rising modes, the first slope mode heating time is 10s, the current is set to 170A, and the voltage is set to 40V; the second fast mode heating time is 1s, the current is set to 400A, and the voltage is set to 40V.

6. Use of a CuCoAg-based high entropy solid solution catalyst synthesized by Joule heat according to the method of any one of claims 1 to 5 in electrocatalytic nitrate to ammonia production.

7. The use according to claim 6, characterized in that The specific process is as follows: the working electrode is a CuCoAg-based high entropy solid solution catalyst fixed on a platinum electrode clip; the reference electrode is a saturated calomel electrode; the counter electrode is a platinum electrode; the electrolyte is a mixed aqueous solution of 0.5mol / LK2SO4+0.1mol / L KNO3, and a linear sweep voltammetry test is performed to obtain the LSV polarization curve of the CuCoAg-based high entropy solid solution catalyst, with the scanning range set to -0.6~-1.6V (vs.SCE) and the scanning rate of 5mV / s; a chronoamperometric analysis is performed with 0.5mol / L K2SO4+0.1mol / L A KNO3 mixed aqueous solution was used as the mixed solution. The test object was a CuCoAg-based high-entropy solid solution catalyst. Multiple potential points were set, and the reaction time at each potential was 1800 seconds. Indigo blue spectrophotometry was used for product quantitative analysis, and the ammonia yield and Faradaic efficiency were calculated. The CuCoAgAlCr high-entropy solid solution catalyst, as an electrocatalyst, exhibited excellent nitrate transamination activity and stability in nitrate transamination, with a Faradaic efficiency of 95.62% and an ammonia yield of 362.255 μmol h-1. -1 cm -2 The CuCoAgAlMnCr high-entropy solid solution catalyst exhibited good stability as an electrocatalyst during the continuous operation of nitrate to ammonia conversion, with a Faradaic efficiency of 98.89% and an ammonia yield of 323.75 μmol h-1. -1 cm -2 .

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