S-doped Cu-Co catalyst and application thereof to electrocatalysis of C-N coupling

Abstract

The application belongs to the field of electrochemical catalyst and energy technology, and particularly relates to a catalyst for electrocatalytic C-N coupling, especially a S-doped Cu-Co catalyst for electrocatalytic C-N coupling, and further discloses a preparation method and application thereof. The S-doped Cu-Co catalyst utilizes copper salt and cobalt salt to form a Cu-Co material and serve as an active site of a reaction, and meanwhile, is synergistically regulated by S atoms. The S-doped Cu-Co catalyst has the advantages of structural stability, high electrolysis activity and long service life in the process of electrolytic catalysis of CO2, and is especially suitable for a process of preparing amides by electrocatalytic C-N coupling of carbon-containing small molecules and nitrogen-containing small molecules.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical catalysts and energy technology, specifically relating to a catalyst for electrocatalytic CN coupling, particularly an S-doped Cu-Co catalyst for electrocatalytic CN coupling, and further disclosing its preparation method and application. Background Technology

[0002] With the increasing severity of global climate change and the energy crisis, the reduction and reuse of carbon dioxide emissions has become a research hotspot. Among these, carbon dioxide electroreduction technology has attracted much attention due to its ability to convert carbon dioxide into valuable chemicals. However, the catalyst efficiency and stability of this technology still face significant challenges, and the field eagerly anticipates the development of novel, highly efficient catalysts to improve process efficiency.

[0003] Similarly, nitrogen is an inexhaustible resource in the atmosphere. Electrocatalytic synthesis of CN-coupled compounds from CO2 and nitrogen-containing substances not only provides an effective way to reduce environmental pollution but also offers new ideas for synthesizing valuable chemical substances such as urea, amides, and organic amines. This innovative method effectively expands the application scope and product categories of electrocatalytic carbon dioxide reduction, significantly outperforming simple carbonaceous species, making this research field extremely promising.

[0004] Amides and their derivatives are a commercially important class of organic compounds, widely used as intermediates in the manufacture of chemical, polymer, and biological compounds. Acetamide, in particular, has a high dielectric constant and is an excellent solvent for many organic and inorganic substances, widely used in various industrial fields. For example, it can be used as a solubilizer for substances with low water solubility in water, as a solvent and solubilizer for dyes in the fiber industry, and as a solvent in some pharmaceutical industries. For instance, Chinese patent CN116732539A discloses a method for synthesizing formamide via electrocatalytic CN coupling, using carbon-containing and nitrogen-containing small molecules as raw materials, through an electrocatalytic CN coupling reaction. In summary, the art attempts to prepare amide materials by achieving CN coupling of carbon dioxide through electrochemical reactions. This method is characterized by its green and environmentally friendly nature and high purity. However, this type of process technology also suffers from the problem of process efficiency being affected by catalyst limitations. The art hopes to develop a catalyst system more suitable for electrocatalytic CN coupling processes, which would be of positive significance for improving the overall efficiency of the process. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to provide an S-doped Cu-Co catalyst for the electrocatalytic preparation of amides by CN coupling. The catalyst has high structural stability and product selectivity, high electrolytic activity and long service life during electrolysis, and effectively solves the problems of unstable structure, low catalytic efficiency and unsatisfactory service life of CN coupling catalysts in the prior art.

[0006] The second technical problem to be solved by the present invention is to provide the application of the above-mentioned S-doped Cu-Co catalyst in the electrocatalytic CN coupling process, especially in the electrocatalytic CN coupling process for preparing amide materials;

[0007] The third technical problem to be solved by the present invention is to provide a method for electrocatalytic CN coupling to synthesize acetamide.

[0008] To solve the above-mentioned technical problems, the present invention provides a method for preparing an S-doped Cu-Co catalyst, comprising the following steps:

[0009] (1) Prepare a precursor solution containing copper salt, cobalt salt and dispersant, and add S atom dopant to mix to obtain catalyst precursor slurry;

[0010] (2) The catalyst precursor slurry is mixed with Nafion solution to obtain the catalyst slurry;

[0011] (3) The catalyst slurry is coated onto the surface of the working electrode substrate to obtain the catalyst slurry.

[0012] Specifically, in the preparation method of the S-doped Cu-Co catalyst, in step (1), the S-atom dopant includes at least one of sodium thiosulfate, ammonium thiosulfate, or thiourea;

[0013] Preferably, the mass ratio of the S-atom dopant to the cobalt salt is 0.1-1:1, more preferably 0.3-0.6:1.

[0014] Specifically, in the preparation method of the S-doped Cu-Co catalyst, in step (1), the dispersant includes at least one of isopropanol, ethanol, or acetone;

[0015] Preferably, the mass ratio of the dispersant to the cobalt salt is 5-10:1, more preferably 5-08:1.

[0016] Specifically, in the preparation method of the S-doped Cu-Co catalyst, in step (1), the mass ratio of the copper salt to the cobalt salt is 0.5-3:1, preferably 1-2:1;

[0017] Preferably, the copper salt includes at least one of copper nitrate, copper sulfate, or copper chloride;

[0018] Preferably, the cobalt salt includes at least one of cobalt nitrate, cobalt sulfate, or cobalt chloride;

[0019] Preferably, the mixing temperature range of the copper salt and the cobalt salt is 20℃-50℃, more preferably 30-40℃.

[0020] Specifically, in the preparation method of the S-doped Cu-Co catalyst, in step (2), the mass ratio of the Nafion solution to the cobalt salt is 0.01-0.1:1, preferably 0.05-0.1:1;

[0021] Preferably, the Nafion solution has a mass concentration of 50-80 wt%.

[0022] Specifically, in the preparation method of the S-doped Cu-Co catalyst, step (3) includes the coating step of coating the catalyst slurry onto the gas diffusion layer (GDL) of the working electrode substrate;

[0023] Preferably, the gas diffusion layer comprises at least one of carbon paper, carbon felt, or carbon cloth;

[0024] Preferably, the coating thickness of the catalyst slurry is 0.1-0.5 μm, more preferably 0.2-0.4 μm;

[0025] Preferably, step (3) further includes a step of drying the catalyst;

[0026] Preferably, the temperature of the drying step is 30-50°C, more preferably 30-40°C;

[0027] Preferably, the drying step takes 10-60 minutes, more preferably 20-40 minutes.

[0028] The present invention also discloses the S-doped Cu-Co catalyst prepared by the method described above;

[0029] Preferably, the loading of the S-doped Cu-Co catalyst is 10-700 mg / cm³. 2 Preferred concentration: 200-700 mg / cm³ 2 .

[0030] The present invention also discloses the application of the S-doped Cu-Co catalyst in the electrocatalytic CN coupling process, especially in the electrocatalytic CN coupling process for preparing amide materials.

[0031] The present invention also discloses a method for electrocatalytic CN coupling to synthesize acetamide, comprising the steps of using carbon-containing small molecules and nitrogen-containing small molecules as raw materials, and performing a CN coupling reaction using the S-doped Cu-Co catalyst as the working electrolyzer;

[0032] Preferably, the carbon-containing small molecules include at least one of carbon dioxide or carbon monoxide;

[0033] Preferably, the nitrogen-containing small molecules include at least one of nitrogen, ammonia, nitric oxide, nitrite, or nitrate.

[0034] Specifically, in the method for electrocatalytic CN coupling to synthesize acetamide, the parameters of the CN coupling reaction include:

[0035] The carbon-containing and nitrogen-containing small molecules are introduced into the cathode electrolyte at the working electrode side. Preferably, the cathode electrolyte is a NaOH or KOH solution; preferably, a NaOH or KOH solution with a concentration of 0.1-2 mol / L, more preferably, a NaOH or KOH solution with a concentration of 0.5-1 mol / L; and / or,

[0036] The counter electrode for the CN coupling reaction is an iridium-tandium electrode; and / or,

[0037] The anolyte for the CN coupling reaction is an H2SO4 solution; preferably an H2SO4 solution with a concentration of 0.1-1 mol / L, more preferably an H2SO4 solution with a concentration of 0.2-0.5 mol / L; and / or,

[0038] The membrane used in the CN coupling reaction includes a proton exchange membrane; and / or,

[0039] The selected carbon-containing small molecule flow rate is 10-50 ml / min, preferably 20-30 ml / min; and / or,

[0040] The selected nitrogen-containing small molecule flow rate is 10-50 ml / min, preferably 20-30 ml / min; and / or,

[0041] The current density applied during the CN coupling reaction is 500-5000 A / m. 2 The preferred applied current density is 1000-2000 A / m. 2 ; and / or,

[0042] The electrolysis time for the CN coupling reaction is 1-3 hours.

[0043] The S-doped Cu-Co catalyst of this invention utilizes copper and cobalt salts to form Cu-Co materials as active sites for the reaction. This not only provides excellent reactive sites for CO2 and nitrogen-containing molecules, effectively promoting the CN coupling reaction and improving product selectivity, but also promotes the adsorption and activation of carbon dioxide, enhancing its loading performance. Simultaneously, through the synergistic regulation of doped S atoms, the synthesized S-doped Cu-Co catalyst introduces S sites, forming a metal-sulfur-carbon catalyst layer, increasing the adsorption capacity for CO2, thereby improving CO2 conversion and effectively enhancing catalyst stability and product selectivity. The S-doped Cu-Co catalyst of this invention exhibits advantages such as structural stability, high electrolytic activity, and long service life in the electrolytic catalytic CO2 production process, and is particularly suitable for the electrocatalytic preparation of amides from carbon-containing and nitrogen-containing small molecules via CN coupling.

[0044] The S-doped Cu-Co catalyst of this invention, through optimized raw material ratios, comprises nanoparticles, which possess advantages such as small size, uniform distribution, and larger specific surface area, allowing for the exposure of more catalyst active sites. Through the synergistic promotion of Cu, Co, and doped S atoms, the gas diffusion electrode of the S-doped Cu-Co catalyst exhibits excellent activity and CO2 conversion rate during electrolysis, demonstrating superior acetamide selectivity and CO2 conversion efficiency, while also exhibiting catalyst stability and a longer lifespan.

[0045] The method for preparing the S-doped Cu-Co catalyst of this invention involves mixing copper salt, cobalt salt, and S-atom dopant. The resulting precursor solution is mixed with Nafion solution and a dispersant, then sprayed onto the surface of the gas diffusion layer (GDL) of the working electrode. After drying, the gas diffusion electrode of the S-doped Cu-Co catalyst is obtained. This method for preparing the S-doped Cu-Co catalyst is simple and easy to implement, making it suitable for widespread application. Detailed Implementation

[0046] Example 1

[0047] The preparation method of the S-doped Cu-Co electrocatalyst coupled with CN in this embodiment includes the following steps:

[0048] (1) Stir 1g of copper chloride, 1g of cobalt chloride and 5g of isopropanol at 30°C to obtain a precursor solution. Then add 0.5g of sodium thiosulfate to the precursor solution and stir to obtain a catalyst precursor slurry.

[0049] (2) Dissolve 0.1g of Nafion solution (commercial reagent, 60wt%, the same below) in the catalyst precursor slurry and stir evenly to obtain the catalyst slurry;

[0050] (3) The catalyst slurry is uniformly sprayed onto carbon paper, and the spraying thickness is controlled to be 0.4 μm. Then it is dried at 40 °C for 30 min to obtain S-doped Cu-Co catalyst electrode.

[0051] Example 2

[0052] The preparation method of the S-doped Cu-Co electrocatalyst coupled with CN in this embodiment includes the following steps:

[0053] (1) 0.5g of copper chloride, 1g of cobalt chloride and 5g of isopropanol are stirred evenly at 30°C to obtain a precursor solution. 0.5g of sodium thiosulfate is added to the precursor solution and stirred evenly to obtain a catalyst precursor slurry.

[0054] (2) Dissolve 0.1g of Nafion solution in the catalyst precursor slurry and stir until homogeneous to obtain the catalyst slurry;

[0055] (3) The catalyst slurry is uniformly sprayed onto the carbon felt, and the spraying thickness is controlled to be 0.4 μm. Then it is dried at 40 °C for 30 min to obtain the S-doped Cu-Co catalyst electrode.

[0056] Example 3

[0057] The preparation method of the S-doped Cu-Co electrocatalyst coupled with CN in this embodiment includes the following steps:

[0058] (1) Stir 1g of copper chloride, 1g of cobalt chloride and 5g of isopropanol at 30°C to obtain a precursor solution. Add 0.5g of sodium thiosulfate to the precursor solution and stir to obtain a catalyst precursor slurry.

[0059] (2) Dissolve 0.1g of Nafion solution in the catalyst precursor slurry and stir until homogeneous to obtain the catalyst slurry;

[0060] (3) The catalyst slurry is uniformly sprayed onto carbon paper, and the spraying thickness is controlled to be 0.2 μm. Then it is dried at 40 °C for 30 min to obtain S-doped Cu-Co catalyst electrode.

[0061] Example 4

[0062] The preparation method of the S-doped Cu-Co electrocatalyst coupled with CN in this embodiment includes the following steps:

[0063] (1) 2g of copper nitrate, 1g of cobalt nitrate and 2g of ethanol are stirred evenly at 40°C to obtain a precursor solution. In addition, 0.6g of ammonium thiosulfate is dissolved in the precursor solution and stirred evenly to obtain a catalyst precursor slurry.

[0064] (2) Dissolve 0.05g of Nafion solution in the catalyst precursor slurry and stir until homogeneous to obtain the catalyst slurry;

[0065] (3) The catalyst slurry is uniformly sprayed onto carbon cloth, and the spraying thickness is controlled to be 0.3 μm. Then it is dried at 30°C for 40 min to obtain S-doped Cu-Co catalyst electrode.

[0066] Example 5

[0067] The preparation method of the S-doped Cu-Co electrocatalyst coupled with CN in this embodiment includes the following steps:

[0068] (1) Stir 1g of copper sulfate, 1g of cobalt sulfate and 3g of acetone at 35°C to obtain a precursor solution. Separately, dissolve 0.3g of thiourea in the precursor solution and stir to obtain a catalyst precursor slurry.

[0069] (2) Dissolve 0.08g of Nafion solution in the catalyst precursor slurry and stir until homogeneous to obtain the catalyst slurry;

[0070] (3) The catalyst slurry is uniformly sprayed onto carbon paper, and the spraying thickness is controlled to be 0.5 μm. Then it is dried at 50 °C for 10 min to obtain S-doped Cu-Co catalyst electrode.

[0071] Example 6

[0072] The preparation method of the S-doped Cu-Co electrocatalyst coupled with CN in this embodiment includes the following steps:

[0073] (1) 1g of copper chloride, 1g of cobalt nitrate and 5g of acetone are stirred evenly at 20°C to obtain a precursor solution. In addition, 0.8g of sodium thiosulfate is dissolved in the precursor solution and stirred evenly to obtain a catalyst precursor slurry.

[0074] (2) Dissolve 0.01g of Nafion solution in the catalyst precursor slurry and stir until homogeneous to obtain the catalyst slurry;

[0075] (3) The catalyst slurry is uniformly sprayed onto carbon paper, and the spraying thickness is controlled to be 0.1 μm. Then it is dried at 30°C for 60 min to obtain S-doped Cu-Co catalyst electrode.

[0076] Example 7

[0077] The preparation method of the S-doped Cu-Co electrocatalyst coupled with CN in this embodiment includes the following steps:

[0078] (1) Stir 3g of copper sulfate, 1g of cobalt chloride and 3g of ethanol at 50°C to obtain a precursor solution. Separately, dissolve 0.2g of ammonium thiosulfate in the precursor solution and stir to obtain a catalyst precursor slurry.

[0079] (2) Dissolve 0.05g of Nafion solution in the catalyst precursor slurry and stir until homogeneous to obtain the catalyst slurry;

[0080] (3) The catalyst slurry is uniformly sprayed onto carbon paper, and the spraying thickness is controlled to be 0.3 μm. Then it is dried at 40 °C for 30 min to obtain S-doped Cu-Co catalyst electrode.

[0081] Example 8

[0082] The preparation method of the S-doped Cu-Co electrocatalyst coupled with CN in this embodiment includes the following steps:

[0083] (1) 1.5g of copper nitrate, 1g of cobalt sulfate, and 4g of isopropanol were stirred evenly at 30°C to obtain a precursor solution. In addition, 0.5g of thiourea was dissolved in the precursor solution and stirred evenly to obtain a catalyst precursor slurry.

[0084] (2) Dissolve 0.1g of Nafion solution in the catalyst precursor slurry and stir until homogeneous to obtain the catalyst slurry;

[0085] (3) The catalyst slurry is uniformly sprayed onto carbon paper, and the spraying thickness is controlled to be 0.2 μm. Then it is dried at 40 °C for 30 min to obtain S-doped Cu-Co catalyst electrode.

[0086] Experimental Example

[0087] 1. Load

[0088] The loading of the catalysts prepared in Examples 1-8 above was determined. Specifically, the metal ion content was determined by the electrode elimination ICP method, and the loading was calculated based on the electrode formulation area.

[0089] The specific test results for the loading of each catalyst in this experimental example are shown in Table 1 below.

[0090] Table 1 Load Results

[0091] serial number Loading capacity (mg / cm2) Example 1 600 Example 2 300 Example 3 300 Example 4 900 Example 5 750 Example 6 150 Example 7 1300 Example 8 450

[0092] It is evident that the S-doped Cu-Co electrocatalyst with CN coupling described in this invention has a high loading capacity.

[0093] 2. Catalytic performance

[0094] Acetamide was prepared by CN coupling reaction using the catalysts prepared in Examples 1-8 as working electrodes and carbon dioxide and ammonia as raw materials.

[0095] In this configuration, carbon dioxide (flow rate 25 ml / min) and ammonia (flow rate 25 ml / min) are passed into a KOH solution (1 mol / L) on the working electrode side. The counter electrode is an iridium electrode, and the electrolyte on the counter electrode side is an H2SO4 solution (0.3 mol / L). A proton exchange membrane separates the electrodes. The anode and cathode are connected to a power source at 2000 A / min. 2 The product was obtained by constant current electrolysis at the current density for 2 hours.

[0096] In this embodiment, the electrodes prepared in Examples 1-8 above are used as CO2 electroreduction cathode materials, at 2000 A / m 2 The current efficiency of acetamide was tested at the current density, and the results are shown in Table 2 below.

[0097] Table 2 Catalytic performance results

[0098]

[0099]

[0100] It can be seen that in the S-doped Cu-Co catalyst coupled to CN in electrocatalysis, the current efficiency generally shows an increasing trend with the increase of Cu-Co catalyst loading per unit area.

[0101] In summary, the S-doped Cu-Co catalyst of this invention utilizes copper and cobalt salts to form Cu-Co materials and incorporates S atoms for synergistic regulation. This not only effectively improves its loading performance and stability but also enhances product selectivity, thereby increasing CO2 conversion and effectively promoting the forward reaction of CN coupling.

[0102] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing an S-doped Cu-Co catalyst, characterized in that, Includes the following steps: (1) Prepare a precursor solution containing copper salt, cobalt salt and dispersant, and add S atom dopant to mix to obtain catalyst precursor slurry; (2) The catalyst precursor slurry is mixed with Nafion solution to obtain the catalyst slurry; (3) The catalyst slurry is coated onto the surface of the working electrode substrate to obtain the catalyst slurry.

2. The method for preparing the S-doped Cu-Co catalyst according to claim 1, characterized in that, In step (1), the S-atom dopant includes at least one of sodium thiosulfate, ammonium thiosulfate, or thiourea. Preferably, the mass ratio of the S-atom dopant to the cobalt salt is 0.1-1:1, more preferably 0.3-0.6:

1.

3. The method for preparing the S-doped Cu-Co catalyst according to claim 1 or 2, characterized in that, In step (1), the dispersant includes at least one of isopropanol, ethanol, or acetone; Preferably, the mass ratio of the dispersant to the cobalt salt is 5-10:1, more preferably 5-8:

1.

4. The method for preparing the S-doped Cu-Co catalyst according to any one of claims 1-3, characterized in that, In step (1), the mass ratio of the copper salt to the cobalt salt is 0.5-3:1, preferably 1-2:1; Preferably, the copper salt includes at least one of copper nitrate, copper sulfate, or copper chloride; Preferably, the cobalt salt includes at least one of cobalt nitrate, cobalt sulfate, or cobalt chloride; Preferably, the mixing temperature range of the copper salt and the cobalt salt is 20℃-50℃, more preferably 30-40℃.

5. The method for preparing the S-doped Cu-Co catalyst according to any one of claims 1-4, characterized in that, In step (2), the mass ratio of the Nafion solution to the cobalt salt is 0.01-0.1:1, preferably 0.05-0.1:1; Preferably, the Nafion solution has a mass concentration of 50-80 wt%.

6. The method for preparing the S-doped Cu-Co catalyst according to any one of claims 1-5, characterized in that, In step (3), the coating step includes coating the catalyst slurry onto the gas diffusion layer (GDL) of the working electrode substrate; Preferably, the gas diffusion layer comprises at least one of carbon paper, carbon felt, or carbon cloth; Preferably, the coating thickness of the catalyst slurry is 0.1-0.5 μm, more preferably 0.2-0.4 μm; Preferably, step (3) further includes a step of drying the catalyst; Preferably, the temperature of the drying step is 30-50°C, more preferably 30-40°C; Preferably, the drying step takes 10-60 minutes, more preferably 20-40 minutes.

7. The S-doped Cu-Co catalyst prepared by the method according to any one of claims 1-6; Preferably, the loading of the S-doped Cu-Co catalyst is 10-600 mg / cm³. 2 Preferred concentration: 200-700 mg / cm³ 2 .

8. The application of the S-doped Cu-Co catalyst of claim 7 in the electrocatalytic CN coupling process, especially in the electrocatalytic CN coupling process for preparing amide materials.

9. A method for electrocatalytic CN coupling to synthesize acetamide, characterized in that, The step includes using carbon-containing small molecules and nitrogen-containing small molecules as raw materials, and carrying out a CN coupling reaction with the S-doped Cu-Co catalyst of claim 7 as the working electrode; Preferably, the carbon-containing small molecules include at least one of carbon dioxide or carbon monoxide; Preferably, the nitrogen-containing small molecules include at least one of nitrogen, ammonia, nitric oxide, nitrite, or nitrate.

10. The method for electrocatalytic CN coupling to synthesize acetamide according to claim 9, characterized in that, The parameters of the CN coupling reaction include: The carbon-containing and nitrogen-containing small molecules are introduced into the cathode electrolyte at the working electrode side. Preferably, the cathode electrolyte is a NaOH or KOH solution; preferably, a NaOH or KOH solution with a concentration of 0.1-2 mol / L, more preferably, a NaOH or KOH solution with a concentration of 0.5-1 mol / L; and / or, The counter electrode for the CN coupling reaction is an iridium-tandium electrode; and / or, The anolyte for the CN coupling reaction is an H2SO4 solution; preferably an H2SO4 solution with a concentration of 0.1-1 mol / L, more preferably an H2SO4 solution with a concentration of 0.2-0.5 mol / L; and / or, The membrane used in the CN coupling reaction includes a proton exchange membrane; and / or, The selected carbon-containing small molecule flow rate is 10-50 ml / min, preferably 20-30 ml / min; and / or, The selected nitrogen-containing small molecule flow rate is 10-50 ml / min, preferably 20-30 ml / min; and / or, The current density applied during the CN coupling reaction is 500-5000 A / m. 2 The preferred applied current density is 1000-2000 A / m. 2 ; and / or, The electrolysis time for the CN coupling reaction is 1-3 hours.

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