Catalyst electrode suitable for carbon dioxide electroreduction and preparation method and application thereof

Abstract

The application discloses a catalyst electrode suitable for carbon dioxide electro-reduction and a preparation method and application thereof in carbon dioxide electro-reduction. The preparation method comprises the following steps: dissolving cuprous oxide and a Nafion solution in a solvent to form a solution A; adding arginine into the solution A and uniformly mixing to obtain a catalyst ink; and coating the catalyst ink on a surface of a substrate and removing the solvent to obtain the catalyst electrode suitable for carbon dioxide electro-reduction. The application changes the structure of the binder Nafion by introducing arginine, so as to change the microenvironment of the catalyst surface, destroy the hydrogen bond network, inhibit the hydrogen evolution reaction, and promote the C-C coupling reaction.

Description

Technical Field

[0001] This invention relates to the fields of electrocatalysis and materials preparation technology, specifically to a catalyst electrode suitable for the electrochemical reduction of carbon dioxide (CO2) to multi-carbon products, its preparation method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Since the Industrial Revolution, the massive emission of greenhouse gas CO2 has caused global warming, leading to frequent natural disasters such as rising sea levels and desertification.

[0004] CO2 electrocatalytic reduction technology can use electricity generated from renewable energy sources to convert CO2 into high-value-added fuels and chemicals.

[0005] Among the products of electroreduction of CO2, multi-carbon products have higher added value, but their formation requires complex multi-electron / proton coupling and carbon-carbon (CC) atom (CC) coupling, resulting in low Faraday efficiency.

[0006] Cu is the only metallic material that can reduce CO2 to produce C2 and C2+ hydrocarbons. It has a relatively moderate binding energy for the CO2 intermediate *CO and the adsorbed *H, which can promote the further coupling of the *CO intermediate to generate multi-carbon products.

[0007] For example, patent specification CN115652340A discloses a silver-modified cuprous oxide electrode for the electrocatalytic reduction of CO2 and its preparation method. Using copper chloride as a precursor, sodium hydroxide as an alkaline diluent, and ascorbic acid as a reducing agent, a bulk cuprous oxide nanostructure is first obtained. Silver nitrate solution is added, and the mixture is vigorously stirred, centrifuged, washed, and vacuum dried to obtain a silver-modified cuprous oxide catalyst. Hydrophilic conductive carbon black is added to prepare a mixed ink, which is then uniformly coated onto carbon paper and dried to obtain the silver-modified cuprous oxide electrode. The prepared silver-modified cuprous oxide electrode exhibits high catalytic activity and good stability. This is because the electrode has abundant silver-copper interfaces; the presence of cuprous oxide improves the selectivity for the product ethylene, while the presence of silver improves the catalyst's stability and inhibits the generation of the competing product hydrogen.

[0008] However, existing Cu-based catalysts still suffer from key problems in the application of electroreduction of CO2 to multi-carbon products, such as low reaction selectivity and intense competition from hydrogen evolution side reactions.

[0009] To address these issues, researchers have explored various catalyst modification strategies, including morphology control, crystal plane engineering, and elemental doping. However, these methods often involve complex synthesis steps or high costs.

[0010] In recent years, influencing product selectivity by regulating the microenvironment of the catalyst interface has become a new research hotspot.

[0011] Nafion, as a binder for preparing catalyst electrodes, not only serves to bond the catalyst and conduct electricity, but also, due to its close contact with the catalyst, its structural changes can affect the microenvironment on the catalyst surface.

[0012] Arginine, as a basic amino acid, has a positively charged guanidine group that can interact with the negatively charged sulfonic acid group in Nafion, thereby changing the structure of Nafion on the catalyst surface.

[0013] Therefore, this invention employs a simple and low-cost method of adding arginine to the catalyst ink to modify the structure of Nafion, thereby regulating the microenvironment on the catalyst surface, promoting the C-C coupling reaction, and improving the selectivity of multi-carbon products. Summary of the Invention

[0014] To address the problems of excessively high CO2 reduction potential, difficult activation, poor selectivity of target products, low Faraday efficiency, and competition from hydrogen evolution side reactions in traditional Cu-based catalysts, this invention provides a catalyst electrode suitable for the electroreduction of carbon dioxide, its preparation method, and its application.

[0015] This invention introduces arginine into an ink containing cuprous oxide, a Nafion solution, and a solvent (preferably isopropanol). The electrostatic interaction between arginine and Nafion alters the configuration of Nafion on the catalyst surface, thereby reconstructing the microenvironment of the catalyst surface, suppressing competition from hydrogen evolution side reactions, and significantly improving the Faradaic efficiency of multi-carbon products. This invention offers a simple and low-cost process, providing a new approach for the efficient electrocatalytic conversion of carbon dioxide into high-value-added chemicals.

[0016] The specific technical solution is as follows: In a first aspect, the present invention provides a method for preparing a catalyst electrode suitable for the electroreduction of carbon dioxide, comprising: Dissolve cuprous oxide and Nafion solution in a solvent to form solution A; Arginine was added to solution A and mixed well to obtain catalyst ink; The catalyst ink is coated onto the substrate surface, and the solvent is removed to obtain the catalyst electrode suitable for carbon dioxide electroreduction.

[0017] This invention modifies the structure of the binder Nafion by introducing arginine, thereby altering the microenvironment on the catalyst surface, disrupting the hydrogen bond network, inhibiting the hydrogen evolution reaction, and promoting the CC coupling reaction.

[0018] In some preferred embodiments, the cuprous oxide is in nanoparticles in the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction.

[0019] In some preferred embodiments, the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction describes that the cuprous oxide has a nanocubic morphology.

[0020] In some preferred embodiments, the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction uses nanocubes with a side length of 200-300 nm, such as 250 nm.

[0021] In some preferred embodiments, the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction uses a Nafion solution with a mass concentration of 0.01% to 25%, such as 1%, 5%, 10%, 20%, etc.

[0022] In some preferred embodiments, in the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction, the mass ratio of cuprous oxide to the volume of the Nafion solution is 1 mg:(1~500) μL, for example, 1 mg:1.25 μL, 1 mg:2.5 μL, 1 mg:5 μL, 1 mg:25 μL, etc.

[0023] In some preferred embodiments, in the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction, the content of cuprous oxide in solution A is 5~10 mg / mL.

[0024] In some preferred embodiments, in the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction, the solvent in solution A includes isopropanol.

[0025] In some preferred embodiments, in the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction, the arginine is added to solution A in solution form.

[0026] In some preferred embodiments, the arginine concentration in the arginine solution of the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction is 0.2~0.8 mol / L, for example 0.4 mol / L, 0.6 mol / L, etc.

[0027] In some preferred embodiments, in the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction, the ratio of the volume of added arginine solution to the volume of solution A is 1:(40~60).

[0028] In some preferred embodiments, the solvent for the arginine solution in the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction includes deionized water.

[0029] In some preferred embodiments, the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction involves ultrasonic mixing to obtain the catalyst ink.

[0030] In some preferred embodiments, the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction involves an ultrasonic time of 30-60 min.

[0031] In some preferred embodiments, in the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction, the mass ratio of cuprous oxide to arginine is 3 mg:(2~4) μmol, more preferably 3 mg:3 μmol.

[0032] In some preferred embodiments, the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction involves coating a catalyst ink with a volume ratio of 100-200 μL:1 cm². 2 .

[0033] In some preferred embodiments, the substrate in the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction includes carbon paper.

[0034] In some preferred embodiments, the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction employs a drying method to remove the solvent.

[0035] In some preferred embodiments, the drying process for the catalyst electrode suitable for carbon dioxide electroreduction is carried out in an air atmosphere.

[0036] In some preferred embodiments, the drying temperature in the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction is 60-70°C.

[0037] In some preferred embodiments, the drying time in the method for preparing the catalyst electrode suitable for carbon dioxide electroreduction is 30-60 min.

[0038] In a second aspect, the present invention provides a catalyst electrode suitable for the electroreduction of carbon dioxide prepared by the preparation method described in the first aspect.

[0039] Thirdly, the present invention provides the application of the catalyst electrode described in the second aspect in the electroreduction of carbon dioxide.

[0040] Furthermore, the catalyst electrode can be used for the electrochemical catalytic reduction of carbon dioxide to produce multi-carbon products.

[0041] Furthermore, the multi-carbon products include one or more of ethylene, ethanol, acetic acid, etc.

[0042] The catalyst electrode of this invention exhibits superior catalytic performance for multi-carbon products (at -500 mA·cm⁻¹). -2 At the current density, the Faraday efficiency of the multi-carbon product increased from 63.2% without the addition of arginine to 83.6%.

[0043] In some preferred embodiments, the present invention uses cuprous oxide nanoparticles with a nanocubic morphology as a catalyst, isopropanol as a solvent, and Nafion as a binder to prepare a catalyst ink. By introducing an additive arginine solution into the ink, the positively charged arginine and the negatively charged Nafion are electrostatically attracted, thereby changing the configuration of Nafion on the surface of cuprous oxide, thus obtaining catalyst electrodes with different Nafion configurations.

[0044] In this invention, the addition of arginine alters the configuration of the Nafion polymer, disrupting the hydrogen bond network at the catalyst interface and suppressing the hydrogen evolution side reaction. The new Nafion configuration promotes the C-C coupling reaction during the reaction process, thereby further generating multi-carbon compounds.

[0045] Compared with the prior art, the beneficial effects of this invention are as follows: 1. By introducing arginine into the catalyst ink and utilizing its electrostatic interaction with Nafion, the configuration of Nafion is changed, creating a unique microenvironment on the catalyst surface. This effectively stabilizes the reaction intermediates, promotes CC coupling, suppresses hydrogen evolution side reactions, and significantly improves the Faraday efficiency of CO2 electroreduction to multiple carbons (from 63.2% to 83.6%). In addition, the catalyst electrode prepared by the method of this invention has good stability.

[0046] 2. The method of the present invention is simple to operate, low in cost, and easy to be applied on a large scale. Attached Figure Description

[0047] Figure 1 X-ray diffraction (XRD) results for electrodes without and with arginine.

[0048] Figure 2 The Fourier transform infrared (FT-IR) spectra of the electrode without arginine and the electrode with arginine are shown.

[0049] Figure 3 X-ray photoelectron spectroscopy (XPS) results for electrodes without and with arginine.

[0050] Figure 4Scanning electron microscope (SEM) images of the electrode without arginine and the electrode with arginine.

[0051] Figure 5 Transmission electron microscopy (TEM) images of the electrode without arginine and the electrode with arginine.

[0052] Figure 6 Fluorine NMR for electrodes without arginine and inks with arginine ( 19 F-NMR results.

[0053] Figure 7 Catalyst electrodes with different concentrations of arginine were tested at -100 mA·cm⁻¹. -2 The Faraday efficiency of CO2 electroreduction to ethylene under constant current density is shown in the figure.

[0054] Figure 8 The graph shows the Faradaic efficiency of different products of CO2 electrocatalytic reduction under constant current density for electrodes without and with arginine. Detailed Implementation

[0055] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0056] Unless otherwise specified, the operating methods in the following examples are generally performed under conventional conditions or as recommended by the manufacturer.

[0057] In the following examples, cuprous oxide nanoparticles can be obtained by referring to existing techniques, such as reference J. Am. Chem. Soc. 2022, 144, 259-269.

[0058] Example 1: Weigh 3 mg of cuprous oxide nanoparticles with a nanocube morphology (side length 250 nm), dissolve 15 μL of 5 wt% Nafion solution in 285 μL of isopropanol, and stir until homogeneous to form solution A; weigh arginine and completely dissolve it in deionized water to prepare solution B with an arginine concentration of 0.4 mol / L; measure 5 μL of solution B and add it to solution A, and sonicate to mix evenly for 30 min to obtain catalyst ink.

[0059] The catalyst ink was evenly coated on a 3 cm layer. 2 The carbon paper surface was dried in air at 70°C for 30 min to remove the solvent, resulting in a catalyst electrode with 0.4 mol / L arginine solution added, named Cu-Arg-0.4.

[0060] Example 2: The only difference from Example 1 is that the concentration of arginine in solution B is 0.6 mol / L, and all other aspects are the same. The resulting catalyst electrode with 0.6 mol / L arginine solution was named Cu-Arg-0.6.

[0061] Example 3: The only difference from Example 1 is that the concentration of arginine in solution B is 0.8 mol / L, and all other aspects are the same. The resulting catalyst electrode with 0.8 mol / L arginine solution was named Cu-Arg-0.8.

[0062] Comparative Example 1: The only difference from Example 1 is that solution B is not added; all other aspects are the same, resulting in a catalyst electrode without arginine, named Cu-Arg-0.

[0063] The XRD results of Cu-Arg-0 and Cu-Arg-0.6 electrodes are as follows: Figure 1 As shown in the figure, the diffraction peaks of the two electrodes match well with the standard card for cuprous oxide, indicating that Nafion and arginine do not affect the crystal structure of cuprous oxide.

[0064] The FT-IR results of Cu-Arg-0 and Cu-Arg-0.6 electrodes are as follows: Figure 2 As shown in the figure. From the figure, we can see that 1650 cm -1 The peaks on the left and right correspond to the vibration of the carbon-oxygen double bond in arginine, indicating that arginine was successfully added to the Cu-Arg-0.6 catalyst electrode.

[0065] Cu 2p XPS results for Cu-Arg-0 and Cu-Arg-0.6 electrodes are as follows: Figure 3 As shown in the figure, there is no strong interaction between arginine and cuprous oxide.

[0066] SEM results of the Cu-Arg-0 and Cu-Arg-0.6 electrode surfaces are as follows: Figure 4 As shown in the figure, the addition of arginine affects the structure of the Nafion layer covering the cuprous oxide surface.

[0067] TEM results of catalyst particles in Cu-Arg-0 and Cu-Arg-0.6 electrodes are as follows: Figure 5 As shown in the figure, the addition of arginine causes the Nafion layer on the cuprous oxide surface to change from a uniform, thin layer to an irregular layer with aggregation, thus thickening the Nafion layer.

[0068] Inks for Cu-Arg-0 and Cu-Arg-0.6 electrodes 19 F-NMR results are as followsFigure 6 As shown in the figure, the addition of arginine caused Nafion to aggregate, restricting molecular rotation and resulting in a weakening of the F element signal.

[0069] Catalyst electrodes with different concentrations of arginine at -100 mA·cm -2 The results of the Faraday efficiency of CO2 electroreduction to ethylene at constant current density are as follows: Figure 7 As shown in the figure, the electrode with the highest ethylene faradaic efficiency was achieved when the arginine concentration was 0.6 mol / L.

[0070] The results of the Faradaic efficiencies of different products of the constant current electroreduction of CO2 using Cu-Arg-0 and Cu-Arg-0.6 electrodes are as follows: Figure 8 As shown in the figure, the Faradaic efficiency of the Cu-Arg-0.6 electrode for the multi-carbon products (ethylene + ethanol + acetic acid) is significantly improved compared to Cu-Arg-0, at -500 mA·cm⁻¹. -2 The current density increased from 63.2% to 83.6%.

[0071] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for preparing a catalyst electrode suitable for the electroreduction of carbon dioxide, characterized in that, include: Dissolve cuprous oxide and Nafion solution in a solvent to form solution A; Arginine was added to solution A and mixed well to obtain catalyst ink; The catalyst ink is coated onto the substrate surface, and the solvent is removed to obtain the catalyst electrode suitable for carbon dioxide electroreduction.

2. The preparation method according to claim 1, characterized in that, The cuprous oxide is in the form of nanoparticles with a nanocubic morphology; The side length of the nanocube is 200~300 nm.

3. The preparation method according to claim 1, characterized in that, The Nafion solution has a mass concentration of 0.01% to 25%. The mass ratio of the cuprous oxide to the volume of the Nafion solution is 1 mg:(1~500) μL; The content of cuprous oxide in solution A is 5~10 mg / mL; The solvent in solution A includes isopropanol.

4. The preparation method according to claim 1, characterized in that, The arginine was added to solution A in solution form; The arginine concentration in the arginine solution is 0.2~0.8 mol / L; The ratio of the volume of arginine solution added to the volume of solution A is 1:(40~60); The solvent for arginine solutions includes deionized water; Catalyst ink was obtained by ultrasonic mixing. The ultrasound time is 30-60 minutes.

5. The preparation method according to claim 1, characterized in that, The mass ratio of cuprous oxide to arginine is 3 mg:(2~4) μmol.

6. The preparation method according to claim 1, characterized in that, The volume ratio of the coated catalyst ink to the substrate surface area is 100~200 μL:1 cm². 2 ; The substrate includes carbon paper; Solvent is removed by drying; The drying is carried out in an air atmosphere; the drying temperature is 60~70℃; and the drying time is 30~60 min.

7. A catalyst electrode suitable for carbon dioxide electroreduction prepared by the preparation method according to any one of claims 1 to 6.

8. The application of the catalyst electrode according to claim 7 in the electroreduction of carbon dioxide.

9. The application according to claim 8, characterized in that, The catalyst electrode is used for the electrochemical catalytic reduction of carbon dioxide to produce multi-carbon products.

10. The application according to claim 9, characterized in that, The multi-carbon products include one or more of ethylene, ethanol, and acetic acid.

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