Preparation method and application of nitrogen-doped carbon-supported copper-iron bimetallic catalyst

Abstract

The present invention relates to a preparation method and application of a nitrogen-doped carbon-supported copper-iron bimetallic catalyst. The preparation method comprises: 1) mixing ferrocyanide with water to obtain solution A; mixing a copper source compound, a reducing metal salt with water to obtain solution B; 2) mixing solution A in step 1) with solution B, reacting at a certain pH, washing and drying the product to obtain a metal-containing complex; 3) calcining the metal-containing complex obtained in step 2) under an inert atmosphere. The catalyst of the present invention exhibits excellent catalytic performance when applied to carbon dioxide electroreduction, and has the characteristics of high selectivity and high stability. In an alkaline electrolyte, CO2 can be selectively electrocatalytically reduced to CO at a low potential, and has a high current density. The preparation method has a simple operating process, low cost, mild reaction conditions, is a green process route, and has potential industrial application value.

Description

Technical Field

[0001] The present invention belongs to the field of electro-reduction of carbon dioxide catalysis, and in particular relates to a preparation method and application of a nitrogen-doped carbon-supported copper-iron bimetallic catalyst. Background Art

[0002] The greenhouse effect caused by carbon dioxide (CO2) has led to global climate anomalies and sparked unprecedented global concern. Electrochemical reduction of CO2 can produce high-value-added chemicals such as hydrocarbons, carbon monoxide, and formic acid. This not only effectively mitigates the greenhouse effect but also supports the natural carbon cycle. This has significant implications for green chemistry and sustainable development, and holds great potential for future applications.

[0003] To improve the performance of CO2 reduction reaction, the preparation of electrocatalysts has become a hot topic of research for scientists. Metal nitrogen-doped carbon materials (MNCs) are one of the most promising non-metallic materials, not only because they have good catalytic performance, can selectively reduce CO2 to CO at low overpotential, and have high CO partial current density in aqueous electrolytes, but also because they can be prepared using relatively simple methods and inexpensive precursors. Typically, this type of solid powder catalyst is prepared by heat treatment of a mixture of metal inorganic salts, a high specific surface area carbon precursor, and one or more low molecular weight or high molecular weight (polymeric) nitrogen-containing precursor compounds (such as phenanthroline, NH3, ethylenediamine, cyclohexylamine, or polyaniline).

[0004] The Fe-NC catalyst prepared by Leta Takele Menisa et al. (Nanoscale, 2020, 12, 16617-16626) can selectively reduce CO2 to CO at a lower potential (-0.5V vs. RHE) and exhibits a maximum Faradaic efficiency of 86.8%, but it still has problems of low current density and poor stability. Leonard et al. (Chem. Sci. 2018, 9, 5064) prepared different catalysts by adding secondary nitrogen precursors to polyaniline-based FeNC materials. Among them, the catalyst prepared from melamine had the highest CO Faradaic efficiency (85%), but the above-mentioned problems were not solved. Compared with the catalytic materials reported, the electrocatalyst prepared by the present invention has a higher current density and higher CO selectivity in the electrochemical reduction of carbon dioxide system. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a preparation method and application of a nitrogen-doped carbon-supported copper-iron bimetallic catalyst to solve the problems of low current density, low selectivity, poor stability, complex preparation process and high energy consumption of existing catalysts.

[0006] To achieve the above-mentioned and other related purposes, one aspect of the present invention provides a method for preparing a nitrogen-doped carbon-supported copper-iron bimetallic catalyst, the preparation method comprising the following steps:

[0007] 1) mixing ferrocyanide with water to obtain solution A; mixing a copper source compound, a reducing metal salt and water to obtain solution B;

[0008] 2) mixing solution A and solution B in step 1), reacting at a certain pH, washing and drying the product to obtain a metal-containing complex;

[0009] 3) calcining the metal-containing complex obtained in step 2) under an inert atmosphere to obtain a nitrogen-doped carbon-supported copper-iron bimetallic catalyst.

[0010] In some embodiments of the present invention, the concentration of solution A is 0.001-0.1 mol / L.

[0011] In some embodiments of the present invention, the concentration of the aqueous solution of the copper source compound is 0.001-0.1 mol / L; the concentration of the aqueous solution of the reducing metal salt is 1-10 times that of the aqueous solution of the copper source compound.

[0012] In some embodiments of the present invention, the mass ratio of the copper source compound to the reducing metal salt is 0.1:1-10:1.

[0013] In some embodiments of the present invention, the mass ratio of the copper source compound to water is 1:1-1:100.

[0014] In some embodiments of the present invention, the mass ratio of the ferrocyanide salt to the copper source compound is 0.1:1-10:1.

[0015] In some embodiments of the present invention, in step 1), the ferrocyanide salt is selected from a combination of one or more of sodium ferrocyanide and potassium ferrocyanide.

[0016] In some embodiments of the present invention, in step 1), the copper source compound is selected from one or more mixed salts of copper chloride, copper nitrate, copper acetate, copper sulfate, and copper oxalate.

[0017] In some embodiments of the present invention, in step 1), the reducing metal salt is selected from one or more mixed salts of sodium citrate, sodium acetate, sodium oxalate, sodium ascorbate, and potassium citrate.

[0018] In some embodiments of the present invention, in step 2), the pH range is 7 to 10; and the standing time is 12 to 24 hours.

[0019] In some embodiments of the present invention, in step 2), the product is washed with an organic solvent; the organic solvent is selected from anhydrous methanol or anhydrous ethanol; and the solid-liquid separation method during the washing process is selected from suction filtration, filter press or centrifugation.

[0020] In some embodiments of the present invention, in step 2), the drying temperature is 60 to 80° C. and the drying time is 12 to 24 hours.

[0021] In some embodiments of the present invention, in step 3), the calcination temperature is 250-350° C., and the heating rate is 2-5° C. / min.

[0022] In some embodiments of the present invention, in step 3), the inert atmosphere is selected from a combination of one or more of nitrogen, argon, and helium; and the gas flow rate is 50 to 120 mL / min.

[0023] Another aspect of the present invention provides a nitrogen-doped carbon-supported copper-iron bimetallic catalyst, which is prepared according to the preparation method of the nitrogen-doped carbon-supported copper-iron bimetallic catalyst described in the first aspect of the present invention.

[0024] Another aspect of the present invention provides use of the nitrogen-doped carbon-supported copper-iron bimetallic catalyst according to the present invention in the electroreduction of carbon dioxide.

[0025] Another aspect of the present invention provides a method for electroreduction of carbon dioxide, comprising the nitrogen-doped carbon-supported copper-iron bimetallic catalyst as described above in the present invention.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention obtains the target product by simply preparing and calcining the precursor, which has a simple operation process, low cost, and good reproducibility. The reaction conditions are mild, and the entire reaction is carried out at room temperature and pressure without the need for an additional acid washing step, meeting the requirements of green chemistry.

[0028] 2. The obtained material is a porous carbon material with good morphology, large specific surface area, and abundant mesopores and micropores. There is no agglomeration of large metal particles, and the particles have good dispersion.

[0029] 3. By constructing a bimetallic nitrogen-carbon composite, the structure and properties of the nitrogen-doped carbon material were improved by varying the raw material ratio and high-temperature calcination temperature to modulate the active sites of CuFe, thereby enhancing the electrochemical performance of the catalyst. The catalyst exhibits excellent catalytic activity and high selectivity. In alkaline electrolyte, it selectively electrocatalyzes the reduction of CO2 to CO at low potentials and high current densities. This indicates a promising development direction for the production of high-value-added chemicals and has promising prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the XRD pattern of the product in Example 1.

[0031] Figure 2 This is a scanning electron microscope image of the product of Example 1 (scale 1 micron).

[0032] Figure 3 This is a scanning electron microscope image of the product of Example 1 (scale 200 nm). DETAILED DESCRIPTION

[0033] Hereinafter, a method for preparing a nitrogen-doped carbon-supported copper-iron bimetallic catalyst and an implementation method thereof are specifically disclosed in detail.

[0034] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0035] After a large number of exploratory experiments, the inventors of the present invention have provided a method for preparing a copper-iron / nitrogen-carbon composite material with high selectivity, high stability and high catalytic performance. The method comprises the following steps: complexing a copper source compound with ferrocyanide, synthesizing the compound through high-temperature pyrolysis, and naturally cooling the resultant to obtain a nitrogen-doped carbon-supported copper-iron bimetallic catalyst material. Specifically, the copper source compound and a reducing metal salt hydrate are dissolved in water to prepare a solution, the pH of the solution is adjusted to a certain value by controlling the amount of metal salt added, and an aqueous solution of ferrocyanide is added to the solution, mixed and allowed to stand at room temperature. A catalytic material precursor is obtained by washing and drying, and then calcined at a certain temperature for a period of time to obtain a nitrogen-doped carbon-supported copper-iron bimetallic catalyst, which solves the problems of low current density, low selectivity, poor stability, complex preparation process and high energy consumption of existing catalysts, meets the requirements of green chemistry, and has good industrial application prospects. The copper-iron / nitrogen-carbon composite material provided by the present invention is prepared into an electrode catalyst and applied to carbon dioxide electroreduction to show excellent catalytic performance, and can highly selectively reduce CO2 to CO. The present invention was completed on this basis.

[0036] In one aspect, the present invention provides a method for preparing a nitrogen-doped carbon-supported copper-iron bimetallic catalyst, the preparation method comprising the following steps:

[0037] 1) mixing ferrocyanide with water to obtain solution A; mixing a copper source compound, a reducing metal salt and water to obtain solution B;

[0038] 2) mixing solution A and solution B in step 1), reacting at a certain pH, washing and drying the product to obtain a metal-containing complex;

[0039] 3) calcining the metal-containing complex obtained in step 2) under an inert atmosphere to obtain a nitrogen-doped carbon-supported copper-iron bimetallic catalyst.

[0040] In the preparation method of the nitrogen-doped carbon-supported copper-iron bimetallic catalyst provided by the present invention, step 1) is to mix ferrocyanide with water to obtain solution A; and to mix a copper source compound, a reducing metal salt and water to obtain solution B.

[0041] In step 1) of the present invention, the concentration of solution A is 0.001-0.1 mol / L. In some embodiments, specifically, the concentration of solution A is 0.001-0.015 mol / L, 0.015-0.025 mol / L, or 0.025-0.1 mol / L.

[0042] In step 1) of the present invention, the concentration of the aqueous solution of the copper source compound is 0.001-0.1 mol / L. In some embodiments, the concentration of the aqueous solution of the copper source compound can be, for example, 0.001-0.015 mol / L, 0.015-0.05 mol / L, or 0.05-0.1 mol / L.

[0043] In step 1) of the present invention, the concentration of the aqueous solution of the reducing metal salt is 1-10 times the concentration of the aqueous solution of the copper source compound. In some embodiments, the concentration of the aqueous solution of the reducing metal salt is, for example, 1-3 times, 3-5 times, 5-8 times, or 8-10 times the concentration of the aqueous solution of the copper source compound.

[0044] In step 1) of the present invention, the mass ratio of the copper source compound to the reducing metal salt is 0.1:1-10:1. In some embodiments, the mass ratio of the copper source compound to the reducing metal salt is 0.1:1-1:1, 1:1-3:1, 3:1-5:1, 5:1-8:1, or 8:1-10:1.

[0045] In step 1) of the present invention, the mass ratio of the copper source compound to water is 1:1-1:100. In some embodiments, the mass ratio of the copper source compound to water can be, for example, 1:1-1:10, 1:10-1:30, 1:30-1:50, 1:50-1:80, or 1:80-1:100.

[0046] In step 1) of the present invention, the mass ratio of the ferrocyanide salt to the copper source compound is 0.1:1-10:1. In some embodiments, the mass ratio of the ferrocyanide salt to the copper source compound can be, for example, 0.1:1-1:1, 1:1-3:1, 3:1-5:1, 5:1-8:1, or 8:1-10:1.

[0047] In step 1) of the present invention, specifically, in some embodiments, the amount of the reducing metal salt added can be 24-40 g / L, 24-30 g / L, 30-36 g / L, or 36-40 g / L. The amount of the copper source compound added can be, for example, 10-50 g / L, 10-20 g / L, 20-30 g / L, 30-40 g / L, or 40-50 g / L. The amount of the ferrocyanide salt added can be, for example, 10-80 g / L, 10-30 g / L, 30-50 g / L, 50-70 g / L, or 70-80 g / L.

[0048] In step 1) of the present invention, the ferrocyanide salt is selected from one or more combinations of sodium ferrocyanide, potassium ferrocyanide, etc. The ferrocyanide salt can be, for example, a ferrocyanide salt hydrate.

[0049] In step 1) of the present invention, the copper source compound is selected from one or more mixed salts of copper chloride, copper nitrate, copper acetate, copper sulfate, copper oxalate, etc.

[0050] In step 1) of the present invention, the reducing metal salt is selected from one or more mixed salts of sodium citrate, sodium acetate, sodium oxalate, sodium ascorbate, potassium citrate, etc. The reducing metal salt can be, for example, a reducing metal salt hydrate.

[0051] In the preparation method of the nitrogen-doped carbon-supported copper-iron bimetallic catalyst provided by the present invention, step 2) is to mix solution A and solution B in step 1), react at a certain pH, and wash and dry the product to obtain a metal-containing complex. Specifically, at a certain pH, the reaction product is allowed to stand at room temperature for a period of time to obtain a reaction product, which is then washed and dried to obtain the metal-containing complex. In some embodiments, the pH range can be, for example, 7-10, 7-8, 8-9, or 9-10. The standing time can be 12-24 hours, 12-18 hours, or 18-24 hours. During the washing step, the product can be washed with an organic solvent; the organic solvent can be selected from anhydrous methanol or anhydrous ethanol. The solid-liquid separation method during the washing process includes suction filtration, filter pressing, or centrifugation. Furthermore, the drying process can be carried out in a vacuum drying oven, for example, and the drying temperature can be 60-80°C, 60-70°C, or 70-80°C. The drying time is, for example, 12 to 24 hours, 12 to 18 hours, or 18 to 24 hours.

[0052] In the preparation method of the nitrogen-doped carbon-supported copper-iron bimetallic catalyst provided by the present invention, step 3) is to calcine the metal-containing complex obtained in step 2) under an inert atmosphere to obtain a nitrogen-doped carbon-supported copper-iron bimetallic catalyst. Specifically, the metal-containing complex obtained in step 2) is calcined under an inert atmosphere for a period of time and naturally cooled to room temperature to obtain. More specifically, the calcination temperature can be, for example, 250-350°C, 250-300°C, 300-350°C, 250-280°C, 280-300°C, 300-320°C, or 320-350°C. The heating rate can be, for example, 2-5°C / min, 2-3°C / min, 3-4°C / min or 4-5°C / min. In step 3), the inert atmosphere is selected from a combination of one or more of nitrogen, argon, and helium; the gas flow rate can be, for example, 50 to 120 mL / min, 50 to 80 mL / min, 80 to 100 mL / min, or 100 to 120 mL / min. Preferably, the gas flow rate is 50 to 80 mL / min.

[0053] Another aspect of the present invention provides a nitrogen-doped carbon-supported copper-iron bimetallic catalyst, which is prepared using the preparation method of the nitrogen-doped carbon-supported copper-iron bimetallic catalyst as described above in the present invention.

[0054] The nitrogen-doped carbon-supported copper-iron bimetallic catalyst prepared by the present invention is a porous carbon material with good morphology and large specific surface area (specific surface area of 50-500m 2 / g), and has abundant mesopores and micropores (mesopore diameter range is 2-50nm, micropore diameter range is 0.3-2nm), no large metal particles agglomerate, and the particles have good dispersion.

[0055] Another aspect of the present invention provides use of the preparation method of the nitrogen-doped carbon-supported copper-iron bimetallic catalyst according to the present invention in the catalysis of electroreduction of carbon dioxide.

[0056] Another aspect of the present invention provides a method for electroreduction of carbon dioxide, comprising the nitrogen-doped carbon-supported copper-iron bimetallic catalyst as described above in the present invention.

[0057] In the method for electroreduction of carbon dioxide provided by the present invention, the device for the CO2 reduction experiment adopts a double-chamber electrolytic cell made of glass. The electrolytic cell is divided into two electrolytic chambers, a cathode and a cathode, and the two chambers are separated by a Nafion117 proton exchange membrane to ensure that only hydrogen ions can pass through. The experiment adopts a three-electrode system, a platinum sheet electrode is placed in the anode electrolytic cell as the anode electrode, a saturated silver-silver chloride electrode is selected as the reference electrode, and a glassy carbon electrode clamp is selected as the working electrode, and both are placed in the cathode electrolytic cell. Nitrogen-doped carbon-supported copper-iron bimetallic catalyst, H2O, isopropanol, and Nafion solution are mixed by ultrasound to form a slurry, evenly coated on carbon paper, and fixed on the glassy carbon electrode clamp. KHCO3 solution is added to both sides of the electrolytic cell. At room temperature and pressure, a CO2 gas flow is introduced for a period of time to saturate the CO2 gas in the solution, and chromatographic detection is started after cyclic voltammetry scanning.

[0058] The beneficial effects of the present invention are:

[0059] 1. The present invention obtains the target product by simply preparing and calcining the precursor, which has a simple operation process, low cost, and good reproducibility. The reaction conditions are mild, and the entire reaction is carried out at room temperature and pressure without the need for an additional acid washing step, meeting the requirements of green chemistry.

[0060] 2. The obtained material is a porous carbon material with good morphology, large specific surface area, and abundant mesopores and micropores. There is no agglomeration of large metal particles, and the particles have good dispersion.

[0061] 3. By constructing a bimetallic nitrogen-carbon composite, the structure and properties of the nitrogen-doped carbon material were improved by varying the raw material ratio and high-temperature calcination temperature to modulate the active sites of CuFe, thereby enhancing the electrochemical performance of the catalyst. The catalyst exhibits excellent catalytic activity and high selectivity. In alkaline electrolyte, it selectively electrocatalyzes the reduction of CO2 to CO at low potentials and high current densities. This indicates a promising development direction for the production of high-value-added chemicals and has promising prospects for industrial application.

[0062] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0063] In the following examples, all reagents, materials and instruments used are commercially available unless otherwise specified.

[0064] Example 1

[0065] Dissolve 2.119g of sodium ferrocyanide in 250mL of deionized water. Add a suitable amount of sodium citrate and 0.72g of copper chloride to the 250mL deionized water, adjusting the amount of sodium citrate to a pH of 7. The two solutions are mixed, allowed to stand at room temperature for 12 hours, and then washed three or more times by centrifugation with anhydrous ethanol. The precipitate is dried in a vacuum oven at 80°C overnight and then calcined in a tube furnace at 300°C under a nitrogen atmosphere for 2 hours at a heating rate of 2.5°C / min to obtain a nitrogen-doped carbon-supported copper-iron bimetallic catalyst material. Figure 1 is the product XRD picture, Figure 2 and Figure 3 This is a scanning electron microscope photo.

[0066] Example 2

[0067] The pH value of the solution was 8, and the other conditions were the same as in Example 1.

[0068] Example 3

[0069] The pH value of the solution was 9, and the other conditions were the same as in Example 1.

[0070] Example 4

[0071] The pH value of the solution was 10, and the other conditions were the same as in Example 1.

[0072] Example 5

[0073] Dissolve 2.119g of sodium ferrocyanide in 250mL of deionized water. Add a suitable amount of sodium citrate and 0.72g of copper chloride to the 250mL deionized water, adjusting the amount of sodium citrate until the pH of the solution reaches approximately 8. The two solutions are mixed, allowed to stand at room temperature for 12 hours, and then washed three or more times by centrifugation with anhydrous ethanol. The precipitate is dried in a vacuum oven at 80°C overnight and then calcined in a tube furnace at 250°C under a nitrogen atmosphere for 2 hours at a heating rate of 2.5°C / min to obtain a carbon-doped copper-iron bimetallic catalyst material.

[0074] Example 6

[0075] The temperature in the tube furnace was 300° C., and the other procedures were the same as in Example 5.

[0076] Example 7

[0077] The temperature in the tube furnace was 350° C., and the other procedures were the same as in Example 5.

[0078] Examples 8 to 11:

[0079] Dissolve 2.119g of sodium ferrocyanide in 250mL of deionized water. Add a certain amount of sodium citrate and copper chloride to the 250mL deionized water, adjusting the amount of sodium citrate until the pH of the solution reaches approximately 8. Combine the two solutions, let them stand at room temperature for 12 hours, and then wash them three or more times by centrifugation with anhydrous ethanol. Dry the precipitate in a vacuum oven at 80°C overnight and then calcine it in a tube furnace at 300°C under a nitrogen atmosphere for 2 hours at a heating rate of 2.5°C / min to obtain a carbon-doped copper-iron bimetallic catalyst. The molar ratio of iron to copper is 1:1.

[0080] Example 9

[0081] The molar ratio of iron and copper is 1:2, and the rest is the same as in Example 8.

[0082] Example 10

[0083] The molar ratio of iron and copper is 1:4, and the rest is the same as in Example 8.

[0084] Example 11

[0085] The molar ratio of iron and copper is 1:8, and the rest is the same as in Example 8.

[0086] Example 12

[0087] Dissolve 4.238g of sodium ferrocyanide in 250mL of deionized water. Add a predetermined amount of sodium acetate and 1g of copper acetate to the 250mL deionized water, adjusting the sodium acetate concentration to a pH of approximately 8. Combine the two solutions, let them stand at room temperature for 12 hours, and then wash them three or more times with anhydrous ethanol by centrifugation. Dry the precipitate in a vacuum oven at 80°C overnight and then calcine it in a tube furnace at 350°C under a nitrogen atmosphere for two hours at a heating rate of 2.5°C / min to obtain a carbon-doped copper-iron bimetallic catalyst.

[0088] Catalytic effect:

[0089] The CO2 reduction experiment used a glass, dual-chamber electrolytic cell. The cell consists of two chambers, the cathode and the anode, separated by a Nafion 117 proton exchange membrane, ensuring that only hydrogen ions can pass through. The experiment employed a three-electrode system: a platinum electrode was placed in the anodic cell, a saturated silver-silver chloride electrode was used as the reference electrode, and a glassy carbon electrode holder was used as the working electrode. Both electrodes were placed in the cathodic cell.

[0090] 4 mg of the prepared catalyst, 100 μL H2O, 300 μL isopropanol, and 40 μL Nafion solution were mixed by ultrasonication to form a slurry, which was evenly coated on a 2 cm 2 Mount the electrode on a piece of carbon paper and secure it to a glassy carbon electrode holder. Add 80 mL of a 0.5 mol / L KHCO₃ solution to each side of the electrolytic cell. At room temperature and pressure, introduce a 30 mL / min CO₂ gas flow for 20 minutes to saturate the solution with CO₂. Perform a cyclic voltammetric scan and begin chromatographic detection.

[0091] The electrocatalytic performance evaluation results of the CuFe / NC catalysts prepared in Examples 1 to 4 are shown in Table 1

[0092] Table 1: Electrocatalytic performance evaluation results of the catalysts prepared in Examples 1 to 4

[0093]

[0094] As shown in Table 1, the CO2 conversion efficiency of CuFe / NC catalyst is above 80% at different pH values. At pH = 8 and -0.7 V vs. RHE potential, the CO separation current reaches 70.8 mA cm -2 .

[0095] The electrocatalytic performance evaluation results of the CuFe / NC catalysts prepared in Examples 5 to 7 are shown in Table 2

[0096] Table 2: Electrocatalytic performance evaluation results of the catalysts prepared in Examples 5 to 7

[0097]

[0098] As shown in Table 2, the CO2 conversion efficiency of CuFe / NC catalyst is above 75% at different reaction temperatures. At a reaction temperature of 350℃ and a potential of -0.7V vs. RHE, the CO separation current reaches 76.6 mA·cm -2 .

[0099] The electrocatalytic performance evaluation results of the CuFe / NC catalysts prepared in Examples 8 to 11 are shown in Table 3.

[0100] Table 3: Electrocatalytic performance evaluation results of the catalysts prepared in Examples 8 to 11

[0101]

[0102]

[0103] As shown in Table 3, the CO2 conversion efficiency of the CuFe / NC catalyst is above 80% at different copper-iron molar ratios. When the copper-iron molar ratio is 1:4 and the CO separation current reaches 79.0 mA cm at a potential of -0.8 V vs. RHE, the CO2 conversion efficiency is 1:4. -2 .

[0104] The electrocatalytic performance evaluation results of the CuFe / NC catalyst prepared in Example 12: Maximum FE CO =91.6%, the corresponding operating voltage is -0.7 V vs. RHE, and the total current density is 88.0 mA cm -2 , CO distribution current is 80.6 mA·cm -2 .

[0105] The evaluation results of the electrocatalytic performance of the CuFe / NC catalysts prepared in Examples 1 to 12 show that the catalysts provided by the present invention have high CO2 electroreduction catalytic activity, can highly selectively reduce CO2 to CO at a lower potential, and have a higher current density.

[0106] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Various variations of the above embodiment of the present invention may be made, differing in material composition. In other words, any simple, equivalent variations and modifications made in accordance with the claims of the present application, i.e., the description, fall within the scope of protection of this patent. Anything not fully described in this invention constitutes conventional technology.

Claims

1. A method for preparing a nitrogen-doped carbon-supported copper-iron bimetallic catalyst, the method comprising the following steps: 1) mixing ferrocyanide with water to obtain solution A; mixing a copper source compound and a reducing metal salt with water to obtain solution B; the ferrocyanide is selected from a combination of one or more of sodium ferrocyanide and potassium ferrocyanide; the copper source compound is selected from one or more mixed salts of copper chloride, copper nitrate, copper acetate, copper sulfate, and copper oxalate; and the reducing metal salt is selected from one or more mixed salts of sodium citrate, sodium acetate, sodium oxalate, sodium ascorbate, and potassium citrate; 2) mixing solution A and solution B in step 1), reacting at a certain pH, washing and drying the product to obtain a metal-containing complex; the pH range is 7 to 8; and the standing time is 12 to 24 hours; 3) calcining the metal-containing complex obtained in step 2) under an inert atmosphere to obtain a nitrogen-doped carbon-supported copper-iron bimetallic catalyst.

2. The method for preparing the nitrogen-doped carbon-supported copper-iron bimetallic catalyst according to claim 1, characterized in that: The concentration of the solution A is 0.001-0.1 mol / L; And / or, the concentration of the aqueous solution of the copper source compound is 0.001-0.1 mol / L; the concentration of the aqueous solution of the reducing metal salt is 1-10 times the concentration of the aqueous solution of the copper source compound; And / or, the mass ratio of the copper source compound to the reducing metal salt is 0.1:1-10:1; And / or, the mass ratio of the copper source compound to water is 1:1-1:100; And / or, the mass ratio of the ferrocyanide salt to the copper source compound is 0.1:1-10:

1.

3. The method for preparing the nitrogen-doped carbon-supported copper-iron bimetallic catalyst according to claim 1, characterized in that: In step 2), the product is washed with an organic solvent; the organic solvent is selected from anhydrous methanol or anhydrous ethanol; the solid-liquid separation method during the washing process is selected from suction filtration, filter press or centrifugation; And / or, in step 2), the drying temperature is 60-80°C; and the drying time is 12-24 hours.

4. The method for preparing the nitrogen-doped carbon-supported copper-iron bimetallic catalyst according to claim 1, wherein: In step 3), the calcination temperature is 250-350°C; and the heating rate is 2-5°C / min.

5. The method for preparing the nitrogen-doped carbon-supported copper-iron bimetallic catalyst according to claim 1, characterized in that: In step 3), the inert atmosphere is selected from a combination of one or more of nitrogen, argon, and helium; and the gas flow rate is 50-120 mL / min.

6. A nitrogen-doped carbon-supported copper-iron bimetallic catalyst, prepared according to the preparation method of the nitrogen-doped carbon-supported copper-iron bimetallic catalyst according to any one of claims 1 to 5.

7. Use of the nitrogen-doped carbon-supported copper-iron bimetallic catalyst according to claim 6 in the electroreduction of carbon dioxide.

8. A method for electroreduction of carbon dioxide, comprising the nitrogen-doped carbon-supported copper-iron bimetallic catalyst as claimed in claim 6.

Images