Preparation of carbon-based hydrophobic catalytic electrode materials and their application in carbon dioxide electrocatalysis

Abstract

The present invention relates to the field of electrocatalysts and discloses a preparation of a carbon-based hydrophobic catalytic electrode material and its application in carbon dioxide electrocatalysis. The preparation method comprises: S1: mixing a suspension containing Ni / Fe hydrotalcite nanoparticles and an organic ligand A with a solution containing an organic ligand B, followed by reflux heating; S2: continuing to add the suspension containing a carbon material and continuing to reflux heating, followed by drying to obtain nitrogen-doped Ni / Fe LDHs nanoparticles coated on the carbon material; S3: grinding the nitrogen-doped Ni / Fe LDHs nanoparticles coated on the carbon material and then calcining to obtain a carbon-based hydrophobic catalytic electrode material; wherein the organic ligand A and the organic ligand B are different nitrogen-containing organic ligands. The carbon-based hydrophobic catalytic electrode material prepared by the preparation method of the present invention can not only inhibit hydrogen evolution catalytic activity and improve carbon dioxide electrochemical reduction activity, but also has good stability.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalysts, and in particular to the preparation of a carbon-based hydrophobic catalytic electrode material and its application in carbon dioxide electrocatalysis. Background Art

[0002] Electrochemical catalysis can convert carbon dioxide into substances such as carbon monoxide. This method can effectively achieve clean chemical production. The types of catalytic electrode materials currently reported for the electrochemical catalytic reduction of carbon dioxide are mainly divided into heterogeneous catalytic materials and homogeneous catalytic materials. Heterogeneous catalytic materials are mainly concentrated in bulk single (multiple) metals, carbon materials and other non-metals, metal single atoms and metal oxides, etc., while homogeneous catalytic materials are mainly some metal complexes. However, homogeneous catalytic materials cannot be reused well. Currently, the most commonly used materials are heterogeneous catalytic materials.

[0003] The development of efficient, stable electrocatalytic materials with high CO2 reduction activity has become a research hotspot. The CO2 reduction reaction is a multi-proton coupling and multi-electron transfer process, and the final products include carbon monoxide (CO), formic acid, formaldehyde, methane, methanol, hydrocarbons and oxygen-containing compounds. CO2 electrocatalytic materials mainly include the following categories: (1) metals (Cu, Au, Ag, Pd, etc.); (2) metal oxides (SnO2, Cu2O, Co3O4, etc.); (3) covalent organic frameworks and metal organic frameworks; (4) molecular catalysts; (5) non-precious metal porous carbon-based catalytic materials. Carbon-based catalytic materials not only have the natural advantage of good conductivity, but also have structural characteristics such as controllable pore structure, large specific surface area and outstanding stability; a series of important breakthroughs have been achieved in CO2 electrocatalysis.

[0004] In recent years, transition metal-nitrogen co-doped porous carbon materials (MNCs) have shown high activity and selectivity in the electrocatalytic reduction of CO2, especially with significantly improved current density. Initially, researchers borrowed the preparation method of oxygen reduction catalysts. The loading amount of transition metals (Ni, Fe, etc.) is usually higher than 10% wt. During the heat treatment process, these transition metal species promote catalytic graphitization and grow a dense layer of graphitized carbon on the surface of the metal particles. Therefore, during the acid washing process, these coated transition metal particles are difficult to remove, which contributes to the hydrogen evolution activity to a certain extent. Taking advantage of the precise control of the structure of transition metal complexes, the development of carbon-supported catalysts is also a promising direction. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the catalytic electrode materials in the prior art, which have high hydrogen evolution activity and poor stability, and to provide a carbon-based hydrophobic catalytic electrode material and its preparation method and application. The carbon-based hydrophobic catalytic electrode material can not only inhibit the catalytic activity of hydrogen evolution and improve the activity of electrochemical reduction of carbon dioxide to carbon monoxide, but also has good stability.

[0006] A first aspect of the present invention provides a method for preparing a carbon-based hydrophobic catalytic electrode material, the preparation method comprising:

[0007] S1: a suspension containing Ni / Fe hydrotalcite nanoparticles and organic ligand A is mixed with a solution containing organic ligand B, and then heated under reflux;

[0008] S2 continues to add the suspension of carbonaceous material and continues to reflux and heat, and then dry to obtain nitrogen-doped Ni / Fe LDHs nanoparticles wrapped on the carbon material;

[0009] S3 Nitrogen-doped Ni / Fe LDHs nanoparticles wrapped on carbon materials were ground and calcined to obtain carbon-based hydrophobic catalytic electrode materials;

[0010] The organic ligand A and the organic ligand B are different nitrogen-containing organic ligands.

[0011] The second aspect of the present invention provides a carbon-based hydrophobic catalytic electrode material prepared by the preparation method of the first aspect of the present invention.

[0012] A third aspect of the present invention provides the use of a carbon-based hydrophobic catalytic electrode material in the electrocatalytic reduction of CO2.

[0013] Compared with the prior art, the carbon-based hydrophobic catalytic electrode material of the present invention has at least the following beneficial effects:

[0014] The carbon-based hydrophobic catalytic electrode material prepared by the preparation method of the present invention can not only inhibit hydrogen evolution activity and improve carbon dioxide electrochemical reduction activity, but also has good stability and good carbon dioxide electrochemical reduction activity during long-term storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 2 is the XRD pattern of the Ni / Fe hydrotalcite nanoparticles prepared in Example 1. DETAILED DESCRIPTION

[0016] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0017] A first aspect of the present invention provides a method for preparing a carbon-based hydrophobic catalytic electrode material, the preparation method comprising:

[0018] S1: a suspension containing Ni / Fe hydrotalcite nanoparticles and organic ligand A is mixed with a solution containing organic ligand B, and then heated under reflux;

[0019] S2 continues to add the suspension of carbonaceous material and continues to reflux and heat, and then dry to obtain nitrogen-doped Ni / Fe LDHs nanoparticles wrapped on the carbon material;

[0020] S3 Nitrogen-doped Ni / Fe LDHs nanoparticles wrapped on carbon materials were ground and calcined to obtain carbon-based hydrophobic catalytic electrode materials;

[0021] The organic ligand A and the organic ligand B are different nitrogen-containing organic ligands.

[0022] In the present invention, the carbon-based hydrophobic catalytic electrode material finally prepared using the preparation method of the present invention not only maintains the advantage of light weight of carbon materials, but also has good carbon dioxide reduction properties and can significantly improve the carbon monoxide Faraday efficiency.

[0023] According to the present invention, a "nitrogen-containing organic ligand" refers to an organic compound containing nitrogen. In some embodiments, the nitrogen-containing organic ligand is selected from one or more of azabicycloalkanes, imidazole ionic liquids, and aminobenzoic acid compounds. While Ni / Fe LDHs nanoparticles alone are detrimental to electron transfer between the electrode and the reactants (products), the inventors have discovered that employing the aforementioned embodiments can significantly improve the poor conductivity of Ni / Fe LDHs nanoparticles and increase the catalytic activity of the catalytic electrode material.

[0024] According to the present invention, in some preferred embodiments, the organic ligand A comprises an azabicycloalkane and an imidazole ionic liquid in a mass ratio of (2-5):1, for example, 2:1, 2.7:1, 3:1, 3.75:1, 4:1, or 5:1, preferably (3-4):1. The aforementioned embodiment not only improves the suspension stability of the Ni / Fe hydrotalcite nanoparticles, facilitating subsequent composite with a carbon material, but also significantly inhibits the hydrogen evolution catalytic activity of the catalytic electrode material, exhibiting high catalytic activity for the reduction of carbon dioxide to carbon monoxide.

[0025] According to the present invention, in some preferred embodiments, the organic ligand B comprises an aminobenzoic acid compound. The above embodiment can increase the catalytic activity and selectivity of the catalytic electrode material to carbon monoxide.

[0026] According to the present invention, as long as the purpose of the present invention can be achieved, the specific selection of the azabicycloalkane is not particularly limited. In some preferred embodiments, the azabicycloalkane is selected from one or more of 7-azabicyclo[2.2.1]heptane, 1,4-diazabicyclo[2.2.2]octane and 1,4-diazabicyclo[3.2.2]nonane.

[0027] According to the present invention, as long as the purpose of the present invention can be achieved, the type of the imidazolium ionic liquid is not particularly limited. In some preferred embodiments, the structure of the imidazolium ionic liquid is as shown in formula (I):

[0028]

[0029] In formula (I), n is an integer of 1-20, and X is selected from CH3COO, H2PO4, PF6, BF4, CF3SO3, HSO4 or NO3.

[0030] According to the present invention, in some preferred embodiments, in formula (I), n is an integer of 8 to 15. The above embodiments can increase the catalytic activity and selectivity of the catalytic electrode material to carbon monoxide.

[0031] According to the present invention, as long as the purpose of the present invention can be achieved, in some preferred embodiments, the aminobenzoic acid compound is selected from one or more of 2-aminoterephthalic acid, 5-aminoisophthalic acid, 2-amino-1,3,5-benzenetricarboxylic acid and 2,3,5,6-tetraaminoterephthalic acid.

[0032] According to the present invention, in some embodiments, the mass ratio of the Ni / Fe hydrotalcite nanoparticles to the organic ligand A is 1:(0.5-2), for example, 1:0.5, 1:1, 1:1.25, 1:1.5, 1:2, and preferably 1:(0.6-1.5). The aforementioned embodiment can increase the specific surface area of ​​the resulting carbon-based hydrophobic catalytic electrode material, thereby improving the adsorption of carbon dioxide by the carbon-based hydrophobic catalytic electrode material, while also improving its catalytic activity for carbon dioxide and its selectivity for carbon monoxide.

[0033] According to the present invention, the suspension containing Ni / Fe hydrotalcite nanoparticles and organic ligand A refers to a suspension obtained by mixing raw materials including Ni / Fe hydrotalcite nanoparticles and organic ligand A with a solvent; the suspension containing carbonaceous material refers to a suspension obtained by mixing raw materials including carbonaceous material with a solvent; and the solution containing organic ligand B refers to a solution obtained by mixing and dissolving raw materials including organic ligand B with a solvent. The solvents used in the Ni / Fe hydrotalcite nanoparticles and organic ligand A, the solution containing organic ligand B, and the suspension of the carbonaceous material can be the same or different, and their specific amounts can be selected as needed. In some embodiments, the solvents in the Ni / Fe hydrotalcite nanoparticles and organic ligand A, the solution containing organic ligand B, and the suspension of the carbonaceous material are each polar solvents, preferably one or more of N,N-dimethylformamide, dimethyl sulfoxide, hexamethylphosphoric triamide, and 1,3-dimethyl-2-imidazolidinone. For the convenience of subsequent treatment, in the present invention, the solvents in the solution containing Ni / Fe hydrotalcite nanoparticles and organic ligand A, the solution containing organic ligand B, and the suspension of carbonaceous material are the same.

[0034] According to the present invention, in some embodiments, the content of the Ni / Fe hydrotalcite nanoparticles in the suspension containing the Ni / Fe hydrotalcite nanoparticles and the organic ligand A is 15-50 mg / ml, for example, 15 mg / ml, 20 mg / ml, 22.5 mg / ml, 25 mg / ml, 35 mg / ml, 45 mg / ml, or 50 mg / ml, preferably 20-35 mg / ml. The aforementioned embodiments can further increase the catalytic activity and selectivity of the catalytic electrode material for carbon dioxide.

[0035] According to the present invention, in some embodiments, the mass ratio of the Ni / Fe hydrotalcite nanoparticles to the organic ligand B is (0.2-1):1, for example, 0.2:1, 0.4:1, 0.47:1, 0.53:1, 0.63:1, 0.7:1, 0.9:1, or 1:1, preferably (0.4-0.7): 1. The aforementioned embodiment can further increase the catalytic activity and selectivity of the catalytic electrode material for carbon dioxide.

[0036] According to the present invention, in some embodiments, the content of organic ligand B in the solution containing organic ligand B is 70-100 mg / ml, for example, 70 mg / ml, 75 mg / ml, 80 mg / ml, 85 mg / ml, 90 mg / ml, or 100 mg / ml, preferably 80-90 mg / ml. The aforementioned embodiment can further increase the catalytic activity and selectivity of the catalytic electrode material for carbon dioxide.

[0037] According to the present invention, in some embodiments, the mass ratio of the Ni / Fe hydrotalcite nanoparticles to the carbon material is (0.1-0.8):1, for example, 0.1:1, 0.2:1, 0.25:1, 0.3:1, 0.5:1, 0.7:1, or 0.8:1, preferably (0.2-0.5):1. The aforementioned embodiment can better increase the catalytic activity and selectivity of the catalytic electrode material for carbon dioxide.

[0038] According to the present invention, in some embodiments, the carbon material content in the carbon-containing material suspension is 65-135 mg / ml, for example, 65 mg / ml, 80 mg / ml, 100 mg / ml, 120 mg / ml, or 1358 mg / ml. Using the aforementioned embodiments can further increase the catalytic activity and selectivity of the catalytic electrode material for carbon dioxide.

[0039] According to the present invention, the choice of carbon material is not particularly limited as long as the objectives of the present invention can be achieved. In some embodiments, the carbon material is selected from one or more of activated carbon, carbon black, carbon nanotubes, graphite, graphene, acetylene black, and Ketjen black, preferably carbon black. The aforementioned embodiments can further enhance the catalytic activity of the catalytic electrode material.

[0040] According to the present invention, in some embodiments, the molar ratio of Ni to Fe in the Ni / Fe hydrotalcite nanoparticles is (2-4):1, for example, 2:1, 3:1, or 4:1. The aforementioned embodiments can better increase the catalytic activity of the catalytic electrode material.

[0041] According to the present invention, as long as the purpose of the present invention can be achieved, the source of the Ni / Fe hydrotalcite nanoparticles is not particularly limited, and they can be obtained commercially or homemade. In some embodiments, the preparation method of the Ni / Fe hydrotalcite nanoparticles is a hydrothermal method, a precipitation method or a hydrothermal precipitation method, preferably a hydrothermal precipitation method.

[0042] According to the present invention, the hydrothermal precipitation method refers to the preparation of Ni / Fe hydrotalcite nanoparticles using a combination of a precipitation method and a hydrothermal method. In some embodiments, the steps of preparing Ni / Fe hydrotalcite nanoparticles using the hydrothermal precipitation method include: contacting a precipitant, a Ni salt, and a trivalent Fe salt in water to obtain a mixed solution; then subjecting the mixed solution to a hydrothermal crystallization reaction; washing the resulting precipitate after the reaction; and finally drying to obtain the Ni / Fe hydrotalcite nanoparticles.

[0043] According to the present invention, in some embodiments, in the mixed solution, the molar ratio of the precipitant to the metal ion is (2-8):1, preferably (3-5):1.

[0044] According to the present invention, the metal ions refer to the metal ions Ni ions and Fe ions in the raw materials for preparing Ni / Fe hydrotalcite nanoparticles.

[0045] According to the present invention, the amount of Ni salt and Fe salt can be selected according to the molar ratio of Ni to Fe required in Ni / Fe hydrotalcite nanoparticles. For example, in Ni salt and Fe salt, the molar ratio of Ni ions to Fe ions is (2-4):1.

[0046] According to the present invention, as long as the purpose of the present invention can be achieved, the selection of the precipitant is not particularly limited. In some embodiments, the precipitant is selected from one or more of urea, ammonium bicarbonate and ammonium carbonate.

[0047] According to the present invention, as long as the precipitant, Ni salt, and Fe salt can form a mixed solution when they are in contact, the contact conditions are not particularly limited. In some embodiments, the contact conditions include: ultrasound at 100-150 kHz and 600-800 W for 5-20 min.

[0048] According to the present invention, when the precipitant, Ni salt and trivalent Fe salt are contacted in water, the amount of water used is not particularly limited, as long as the hydrothermal crystallization reaction can proceed smoothly and finally form the corresponding Ni / Fe hydrotalcite nanoparticles. This method is a conventional method in the art and will not be described in detail here.

[0049] According to the present invention, as long as the purpose of the present invention can be achieved, the conditions of the hydrothermal crystallization reaction are not particularly limited. In some embodiments, the conditions of the hydrothermal crystallization reaction include: a reaction temperature of 150-170°C.

[0050] According to the present invention, in some embodiments, the conditions of the hydrothermal crystallization reaction include: a reaction time of 4-9 hours.

[0051] According to the present invention, when preparing Ni / Fe hydrotalcite nanoparticles, there is no special restriction on the number of water washings, which is generally 2-5 times. There is no restriction on the drying conditions, and the particles can be dried at 50-70°C to a constant weight (a constant weight is considered to be reached if the difference between the two weighings is less than 0.2 mg).

[0052] According to the present invention, as long as the purpose of the present invention can be achieved, the reflux heating conditions in step S1 and step S2 are not particularly limited. In some embodiments, in step S1 and step S2, the reflux heating temperature is respectively 120-180°C, preferably 140-160°C.

[0053] According to the present invention, in some embodiments, in step S1, the reflux heating time is 10-60 min, preferably 20-40 min.

[0054] According to the present invention, in some embodiments, in step S2, the reflux heating time is 1-10 hours, preferably 3-7 hours.

[0055] According to the present invention, the purpose of drying in step S2 is to remove excess solvent. In the present invention, there is no special limitation on the drying conditions, for example, drying at 140-160° C. for 15-30 h.

[0056] According to the present invention, the grinding in step S3 is a conventional technical means in the art, and there is no special limitation on this in the present invention, so it will not be described in detail here.

[0057] According to the present invention, in some embodiments, in step S3, the calcination conditions include: in a protective gas atmosphere, heating to 400-450°C (e.g., 400°C, 450°C, or 500°C) at a heating rate of 3-8°C / min (e.g., 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, or 8°C / min) and maintaining for 0.5-1h (e.g., 0.5h, 0.8h, or 1h), ... in, 7°C / min or 8°C / min) to 550-650°C (for example, 550°C, 600°C or 650°C) and maintain for 0.5-1h (for example, 0.5h, 0.8h or 1h), and then to 750-850°C (for example, 750°C, 800°C or 850°C) at a heating rate of 3-8°C / min (for example, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min or 8°C / min) and maintain for 1-2h (for example, 1h, 1.5h or 2h). The above-mentioned embodiment can not only better increase the stability of the catalytic electrode, but also inhibit the generation of hydrogen evolution reaction and increase the catalytic activity of the catalyst. The inventor speculates that under the above-mentioned embodiment, the catalytic electrode material partially forms a spinel structure. The partial spinel structure present in the catalytic electrode material of the present invention makes the catalytic electrode material more stable, and the structure formed during the calcination process is more conducive to the adsorption of carbon dioxide and the reduction and dissociation of carbon dioxide.

[0058] The second aspect of the present invention provides a carbon-based hydrophobic catalytic electrode material prepared by the preparation method of the first aspect of the present invention.

[0059] In the present invention, the carbon-based hydrophobic catalytic electrode material not only has good structural stability but also has good carbon dioxide catalytic activity and carbon monoxide selectivity.

[0060] A third aspect of the present invention provides the use of a carbon-based hydrophobic catalytic electrode material in the electrocatalytic reduction of CO2.

[0061] The present invention will be described in detail below by way of examples. In the following examples and comparative examples:

[0062] Carbon black was a commercial product of Zhengzhou Alpha Chemical Co., Ltd. with the trademark 1333-86-4;

[0063] Preparation of the electrode: Take 1.4-2 mg of the carbon-based hydrophobic catalytic electrode material prepared in the embodiment and the comparative example respectively. The specific steps are as follows: add 1.4-2 mg of electrode material powder to 2-3 ml of anhydrous ethanol, ultrasonically disperse the powder for 15 minutes to uniformly disperse the powder to form a dispersion, and then add a PTFE emulsion with a concentration of 5 wt% to the dispersion, and continue ultrasonicating for 15 minutes to form a uniform black sample dispersion; draw 10-20 μL of the sample dispersion and carefully load the center of the glassy carbon electrode (GCE, diameter 3 mm). The catalyst loading in the catalyst-loaded glassy carbon electrode is 1-1.3 mg / cm 2 , the glassy carbon electrode loaded with the catalyst was dried at room temperature before use;

[0064] Initial electrochemical test: Using a catalyst-loaded glassy carbon electrode as the working electrode, a Pt sheet as the counter electrode, a KCl-saturated Ag / AgCl electrode as the reference electrode, and 0.5 mol / L potassium bicarbonate as the electrolyte, the electrocatalytic reduction of carbon dioxide was tested. The operating voltage applied to the electrolytic cell was 0.1-0.2 V.

[0065] Faraday efficiency test and calculation of electrochemical reduction of carbon dioxide to produce carbon monoxide: The Faraday efficiency calculation method is Faraday Efficiency = (m*n*F) / (I*t), where m is the actual number of moles of the product, n is the number of reaction electrons, F is the Faraday constant, that is, the number of charges contained in an electron, I is the current, and t is the time.

[0066] The prepared glassy carbon electrode loaded with the catalyst was placed in an environment of 25±5°C and 70±10% RH for one month and then tested according to the method of the initial electrochemical test. The Faraday efficiency of the electrochemical reduction of carbon dioxide to carbon monoxide of the glassy carbon electrode loaded with the catalyst was tested one month later.

[0067] Example 1

[0068] Preparation of Ni / Fe hydrotalcite nanoparticles:

[0069] 8 mol of urea, 1.5 mol of Ni(NO3)2, and 0.5 mol of Fe(NO3)3 were mixed in 5000 mL of water, and then ultrasonicated at 120 kHz and 700 W for 10 min to obtain a mixed solution; the mixed solution was poured into a stainless steel reactor lined with polytetrafluoroethylene, sealed, and reacted at 160°C for 8 h. After the reactor was naturally cooled to room temperature, the white precipitate product was washed three times with deionized water and dried at 65°C to constant weight to obtain Ni / Fe hydrotalcite nanoparticles;

[0070] Figure 1 The XRD pattern of the Ni / Fe hydrotalcite nanoparticles prepared in Example 1 is shown in FIG. Figure 1 This shows that the prepared Ni / Fe hydrotalcite nanoparticles have regular morphology.

[0071] Preparation of carbon-based hydrophobic catalytic electrode materials:

[0072] S1 45 mg of Ni / Fe hydrotalcite nanoparticles, 45 mg of 1,4-diazabicyclo[2.2.2]octane, 12 mg of 1-hexadecyl-3-methylimidazolium tetrafluoroborate and 2 ml of N,N-dimethylformamide were added to a round-bottom flask and stirred for 2 minutes to obtain a suspension containing Ni / Fe hydrotalcite nanoparticles, 1,4-diazabicyclo[2.2.2]octane and 1-hexadecyl-3-methylimidazolium tetrafluoroborate; 85 mg of 2-aminobenzene was added. Dicarboxylic acid was dispersed in 1 ml of N,N-dimethylformamide to obtain a solution containing 2-aminoterephthalic acid. A suspension containing Ni / Fe hydrotalcite nanoparticles, 1,4-diazabicyclo[2.2.2]octane, and 1-hexadecyl-3-methylimidazolium tetrafluoroborate was mixed with the solution containing 2-aminoterephthalic acid. Then, a round-bottom flask was placed in an oil bath, and a condenser was installed at the flask mouth and connected to circulating cooling water. The reactants in the round-bottom flask were stirred and heated at 150°C for 30 minutes.

[0073] S2: 150 mg of carbon black was dispersed in 1.5 ml of N,N-dimethylformamide to obtain a suspension containing carbon black. The suspension containing carbon black was added to the reaction solution of step S1, and reflux heating was continued at 150° C. for 5 h. After the reaction was completed, the mixture was dried in an oven at 150° C. for 20 h to obtain nitrogen-doped Ni / Fe LDHs nanoparticles coated on carbon black.

[0074] S3 Grind the nitrogen-doped Ni / Fe LDHs nanoparticles wrapped on carbon black and then calcine them (the calcination conditions are in a nitrogen atmosphere, heating to 400°C at a heating rate of 5°C / min and holding for 1 hour, heating to 500°C at a heating rate of 5°C / min and holding for 0.5 hour, heating to 800°C at a heating rate of 5°C / min and holding for 1.5 hours) to obtain a carbon-based hydrophobic catalytic electrode material.

[0075] Carbon dioxide is electrochemically reduced to produce carbon monoxide. The Faraday efficiency of the electrochemical reduction of carbon dioxide to produce carbon monoxide is distributed between 70% and 84%. After one month, the Faraday efficiency of the electrochemical reduction of carbon dioxide to produce carbon monoxide is distributed between 70% and 78%.

[0076] Example 2

[0077] Preparation of Ni / Fe hydrotalcite nanoparticles:

[0078] 8 mol of urea, 2 mol of Ni(NO3)2, and 1 mol of Fe(NO3)3 were mixed in 5000 mL of water, and then ultrasonicated at 100 kHz and 800 W for 20 min to obtain a mixed solution. The mixed solution was poured into a stainless steel reactor lined with polytetrafluoroethylene, sealed, and reacted at 170°C for 7 h. After the reactor was naturally cooled to room temperature, the white precipitate was washed three times with deionized water and dried at 70°C to constant weight to obtain Ni / Fe hydrotalcite nanoparticles.

[0079] XRD patterns of Ni / Fe hydrotalcite nanoparticles and Figure 1 similar.

[0080] Preparation of carbon-based hydrophobic catalytic electrode materials:

[0081] S1 50 mg of Ni / Fe hydrotalcite nanoparticles, 40 mg of 1,4-diazabicyclo[3.2.2]nonane, 15 mg of 1-decyl-3-methylimidazolium tetrafluoroborate and 2 ml of N,N-dimethylformamide were added to a round-bottom flask and stirred for 2 minutes to obtain a suspension containing Ni / Fe hydrotalcite nanoparticles, 1,4-diazabicyclo[3.2.2]nonane and 1-decyl-3-methylimidazolium tetrafluoroborate; 80 mg of 5-aminoisophthalic acid was added. Formic acid was dispersed in 1 mL of N,N-dimethylformamide to obtain a solution containing 5-aminoisophthalic acid. A suspension containing Ni / Fe hydrotalcite nanoparticles, 1,4-diazabicyclo[3.2.2]nonane, and 1-decyl-3-methylimidazolium tetrafluoroborate was mixed with the solution containing 5-aminoisophthalic acid. Then, a round-bottom flask was placed in an oil bath, and a condenser was installed at the flask mouth and connected to circulating cooling water. The reactants in the round-bottom flask were stirred and heated at 150°C for 30 minutes.

[0082] S2: 150 mg of carbon black was dispersed in 1.5 ml of N,N-dimethylformamide to obtain a suspension containing carbon black. The suspension containing carbon black was added to the reaction solution of step S1, and reflux heating was continued at 150° C. for 5 h. After the reaction was completed, the mixture was dried in an oven at 150° C. for 20 h to obtain nitrogen-doped Ni / Fe LDHs nanoparticles coated on carbon black.

[0083] S3 Grind the nitrogen-doped Ni / Fe LDHs nanoparticles wrapped on carbon black and then calcine them (the calcination conditions are in a nitrogen atmosphere, heating to 400°C at a heating rate of 7°C / min and holding for 1 hour, heating to 550°C at a heating rate of 5°C / min and holding for 1 hour, heating to 850°C at a heating rate of 5°C / min and holding for 1 hour) to obtain a carbon-based hydrophobic catalytic electrode material.

[0084] Carbon dioxide is electrochemically reduced to produce carbon monoxide. The distributed Faraday efficiency of the electrochemical reduction of carbon dioxide to produce carbon monoxide is 68%-80%. The Faraday efficiency of the electrochemical reduction of carbon dioxide to produce carbon monoxide after one month is 53%-77%.

[0085] Example 3

[0086] The preparation of Ni / Fe hydrotalcite nanoparticles was the same as in Example 1;

[0087] Preparation of carbon-based hydrophobic catalytic electrode materials:

[0088] S1 40 mg of Ni / Fe hydrotalcite nanoparticles, 40 mg of 7-azabicyclo[2.2.1]heptane, 10 mg of 1-decyl-3-methylimidazolium trifluoromethanesulfonate and 2 ml of N,N-dimethylformamide were added to a round-bottom flask and stirred for 2 minutes to obtain a suspension containing Ni / Fe hydrotalcite nanoparticles, 7-azabicyclo[2.2.1]heptane and 1-decyl-3-methylimidazolium trifluoromethanesulfonate; 85 mg of 5-aminoisophthalic acid was added. The acid was dispersed in 1 mL of N,N-dimethylformamide to obtain a solution containing 5-aminoisophthalic acid. The suspension containing Ni / Fe hydrotalcite nanoparticles, 7-azabicyclo[2.2.1]heptane, and 1-decyl-3-methylimidazolium trifluoromethanesulfonate was mixed with the solution containing 5-aminoisophthalic acid. After that, the round-bottom flask was placed in an oil bath, and a condenser was installed at the flask mouth and connected to circulating cooling water. The reactants in the round-bottom flask were stirred and heated at 150°C for 30 min.

[0089] S2: 120 mg of carbon black was dispersed in 1.5 ml of N,N-dimethylformamide to obtain a suspension containing carbon black. The suspension containing carbon black was added to the reaction solution of step S1, and reflux heating was continued at 150° C. for 5 h. After the reaction was completed, the mixture was dried in an oven at 150° C. for 20 h to obtain nitrogen-doped Ni / Fe LDHs nanoparticles coated on carbon black.

[0090] S3 Grind the nitrogen-doped Ni / Fe LDHs nanoparticles wrapped on carbon black and then calcine them (the calcination conditions are in a nitrogen atmosphere, heating to 400°C at a heating rate of 8°C / min and holding for 0.5h, heating to 550°C at a heating rate of 5°C / min and holding for 1h, heating to 750°C at a heating rate of 5°C / min and holding for 2h) to obtain a carbon-based hydrophobic catalytic electrode material.

[0091] The electrochemical reduction of carbon dioxide to produce carbon monoxide has a Faraday efficiency of 66%-78% and a Faraday efficiency of 63%-74% after one month, as shown in Table 1.

[0092] Example 4

[0093] The method of Example 1 is as follows, except that:

[0094] When preparing the carbon-based hydrophobic catalytic electrode material, no 1-hexadecyl-3-methylimidazolium tetrafluoroborate was present, and the amount of 1,4-diazabicyclo[2.2.2]octane used was 57 mg.

[0095] Carbon dioxide is electrochemically reduced to produce carbon monoxide. The Faraday efficiency of the electrochemical reduction of carbon dioxide to produce carbon monoxide is distributed between 54% and 66%. After one month, the Faraday efficiency of the electrochemical reduction of carbon dioxide to produce carbon monoxide is distributed between 45% and 55%.

[0096] Example 5

[0097] The method of Example 1 is as follows, except that:

[0098] 1-Hexadecyl-3-methylimidazolium tetrafluoroborate was replaced by 1-ethyl-3-methylimidazolium hexafluorophosphate.

[0099] Carbon dioxide is electrochemically reduced to produce carbon monoxide, and its highest reduction potential of CO2 is 0.17V. The Faraday efficiency of carbon dioxide electrochemical reduction to produce carbon monoxide is distributed between 64% and 73%. After one month, the Faraday efficiency of carbon dioxide electrochemical reduction to produce carbon monoxide is distributed between 54% and 62%.

[0100] Example 6

[0101] The method of Example 1 is as follows, except that:

[0102] The calcination conditions were as follows: in a nitrogen atmosphere, the temperature was raised to 800°C at a heating rate of 5°C / min and maintained for 3 h.

[0103] Carbon dioxide is electrochemically reduced to produce carbon monoxide, and its highest reduction potential of CO2 is 0.17V. The Faraday efficiency of carbon dioxide electrochemical reduction to produce carbon monoxide is distributed between 65% and 74%. After one month, the Faraday efficiency of carbon dioxide electrochemical reduction to produce carbon monoxide is distributed between 51% and 58%.

[0104] Comparative Example 1

[0105] The method of Example 1 is as follows, except that:

[0106] 2-Aminoterephthalic acid was replaced by 1,4-diazabicyclo[2.2.2]octane and 1-hexadecyl-3-methylimidazolium tetrafluoroborate.

[0107] Carbon dioxide is electrochemically reduced to produce carbon monoxide, and its highest reduction potential of CO2 is 0.17V. The Faraday efficiency of carbon dioxide electrochemical reduction to produce carbon monoxide is distributed between 41% and 53%. After one month, the Faraday efficiency of carbon dioxide electrochemical reduction to produce carbon monoxide is distributed between 29% and 33%.

[0108] It can be seen from the results of the examples and comparative examples that the carbon-based hydrophobic catalytic electrode material prepared by the preparation method of the present invention can not only inhibit the catalytic activity of hydrogen evolution, improve the electrochemical reduction activity of carbon dioxide and the selectivity of carbon monoxide, but also has good stability and can be used stably during long-term storage.

[0109] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing a carbon-based hydrophobic catalytic electrode material, the method comprising: S1: a suspension containing Ni / Fe hydrotalcite nanoparticles and organic ligand A is mixed with a solution containing organic ligand B, and then refluxed; S2: adding the carbonaceous material suspension and continuing to reflux and heat, followed by drying to obtain nitrogen-doped Ni / Fe LDHs nanoparticles wrapped on the carbon material; S3: Nitrogen-doped Ni / Fe LDHs nanoparticles coated on carbon materials are ground and then calcined to obtain carbon-based hydrophobic catalytic electrode materials; Wherein, the organic ligand A and the organic ligand B are different nitrogen-containing organic ligands; The nitrogen-containing organic ligand is selected from one or more of azabicycloalkanes, imidazole ionic liquids and aminobenzoic acid compounds; The organic ligand A comprises azabicycloalkane and imidazole ionic liquid, and the mass ratio thereof is (2-5):1; The organic ligand B includes an aminobenzoic acid compound; The solvents in the solution containing Ni / Fe hydrotalcite nanoparticles and organic ligand A, the solution containing organic ligand B, and the suspension of carbonaceous material are each polar solvents; The polar solvent is one or more of N,N-dimethylformamide, dimethyl sulfoxide, hexamethylphosphoric triamide and 1,3-dimethyl-2-imidazolidinone; The calcination atmosphere is an inert atmosphere.

2. The preparation method according to claim 1, wherein The organic ligand A includes azabicycloalkane and imidazole ionic liquid, and the mass ratio thereof is (3-4):

1.

3. The preparation method according to claim 1, wherein The azabicycloalkane is selected from one or more of 7-azabicyclo[2.2.1]heptane, 1,4-diazabicyclo[2.2.2]octane and 1,4-diazabicyclo[3.2.2]nonane; and / or The structure of the imidazole ionic liquid is shown in formula (I): Formula (I), In formula (I), n is an integer of 1-20, and X is selected from CH3COO, H2PO4, PF6, BF4, CF3SO3, HSO4 or NO3; and / or The aminobenzoic acid compound is selected from one or more of 2-aminoterephthalic acid, 5-aminoisophthalic acid, 2-amino-1,3,5-benzenetricarboxylic acid and 2,3,5,6-tetraaminoterephthalic acid.

4. The preparation method according to claim 3, wherein In formula (I), n is an integer of 8-15.

5. The preparation method according to claim 1, wherein The mass ratio of the Ni / Fe hydrotalcite nanoparticles to the organic ligand A is 1:(0.5-2); and / or In the suspension containing Ni / Fe hydrotalcite nanoparticles and organic ligand A, the content of the Ni / Fe hydrotalcite nanoparticles is 15-50 mg / ml; and / or The mass ratio of the Ni / Fe hydrotalcite nanoparticles to the organic ligand B is (0.2-1): 1; and / or The content of organic ligand B in the solution containing organic ligand B is 70-100 mg / ml; and / or The mass ratio of the Ni / Fe hydrotalcite nanoparticles to the carbon material (0.1-0.8): 1; and / or The content of the carbon material in the carbon material suspension is 65-135 mg / ml.

6. The preparation method according to claim 5, wherein The mass ratio of the Ni / Fe hydrotalcite nanoparticles to the organic ligand A is 1:(0.6-1.5); and / or In the suspension containing Ni / Fe hydrotalcite nanoparticles and organic ligand A, the content of the Ni / Fe hydrotalcite nanoparticles is 20-35 mg / ml; and / or The mass ratio of the Ni / Fe hydrotalcite nanoparticles to the organic ligand B is (0.4-0.7):1; and / or The content of organic ligand B in the solution containing organic ligand B is 80-90 mg / ml; and / or The mass ratio of the Ni / Fe hydrotalcite nanoparticles to the carbon material is (0.2-0.5):

1.

7. The preparation method according to claim 1, wherein The carbon material is selected from one or more of activated carbon, carbon black, carbon nanotubes, graphite, graphene, acetylene black and Ketjen black.

8. The preparation method according to claim 1, wherein The carbon material is carbon black.

9. The preparation method according to claim 1, wherein Calculated on the basis of element molar amounts, the molar ratio of Ni to Fe in Ni / Fe hydrotalcite nanoparticles is (2-4):

1.

10. The preparation method according to claim 9, wherein The preparation method of the Ni / Fe hydrotalcite nanoparticles is a hydrothermal method, a precipitation method or a hydrothermal precipitation method.

11. The preparation method according to claim 10, wherein The preparation method of the Ni / Fe hydrotalcite nanoparticles is a hydrothermal precipitation method.

12. The preparation method according to claim 11, wherein The steps of preparing Ni / Fe hydrotalcite nanoparticles using a hydrothermal precipitation method include: contacting a precipitant, a Ni salt and a trivalent Fe salt in water to obtain a mixed solution; then subjecting the mixed solution to a hydrothermal crystallization reaction, washing the obtained precipitate with water after the reaction, and finally drying to obtain the Ni / Fe hydrotalcite nanoparticles.

13. The preparation method according to claim 12, wherein In the mixed solution, the molar ratio of the precipitant to the metal ion is (2-8):1; and / or The precipitant is selected from one or more of urea, ammonium bicarbonate and ammonium carbonate; and / or The contact conditions include: ultrasound at 100-150kHz, 600-800W for 5-20min; and / or The conditions of the hydrothermal crystallization reaction include: a reaction temperature of 150-170° C. and / or a reaction time of 4-9 hours.

14. The preparation method according to claim 13, wherein In the mixed solution, the molar ratio of the precipitant to the metal ion is (3-5):

1.

15. The preparation method according to claim 1, wherein In step S1 and step S2, the reflux heating temperature is 120-180° C. respectively; In step S1, the reflux heating time is 10-60 min; In step S2, the reflux heating time is 1-10 hours.

16. The preparation method according to claim 15, wherein In step S1 and step S2, the reflux heating temperature is 140-160° C. respectively; In step S1, the reflux heating time is 20-40 minutes; In step S2, the reflux heating time is 3-7 hours.

17. The preparation method according to claim 1, wherein In step S3, the calcination conditions include: in a protective gas atmosphere, heating to 400-450°C at a heating rate of 3-8°C / min and maintaining for 0.5-1h, heating to 550-650°C at a heating rate of 3-8°C / min and maintaining for 0.5-1h, and heating to 750-850°C at a heating rate of 3-8°C / min and maintaining for 1-2h.

18. A carbon-based hydrophobic catalytic electrode material prepared according to the preparation method according to any one of claims 1 to 17.

19. Use of the carbon-based hydrophobic catalytic electrode material according to claim 18 in CO2 electrocatalytic reduction.

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