A cationic polymer-coated copper-based catalyst, and a preparation method and application thereof

Abstract

The present application relates to a kind of cationic polymer coated copper-based catalyst and its preparation method and application, belong to catalyst technical field.The preparation method of the present application includes the following steps: adding copper nanoparticles to quaternary ammonium spiral piperazine solution, stirring uniformly and adjusting pH to 9-13, then adding 1,3,5-benzene tricarbonyl chloride solution to react, obtain cationic polymer coated copper-based catalyst.The cationic polymer coated copper-based catalyst is through the mechanism of "static electric enrichment-coordination stabilization-crosslinking reinforcement", in the electrolytic cell under acidic condition, it shows excellent carbon dioxide electrocatalytic reduction performance, can efficiently prepare ethanol, at 250mA / cm 2 The current density of 50% faradaic efficiency is realized.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, and particularly relates to a copper-based catalyst coated with a cationic polymer, its preparation method and application. Background Technology

[0002] In recent years, electrocatalytic carbon dioxide reduction (CO2RR) technology has attracted much attention due to its ability to convert greenhouse gases into high-value-added chemicals. Among these, the direct electrocatalytic reduction of carbon dioxide to multi-carbon products (such as ethylene, ethanol, and propanol) is considered a key pathway for achieving carbon resource recycling. Ethanol (C2H5OH), as a high-energy-density liquid fuel and an important chemical raw material, can simultaneously alleviate energy shortages and carbon emission problems through its efficient synthesis, demonstrating significant economic and environmental benefits.

[0003] Existing electrocatalytic systems for ethanol production under acidic conditions face numerous challenges. First, intense competition for HER (ether-reactive oxygen species) in acidic environments leads to low CO2RR efficiency, catalyst deactivation, and poor mass transfer. Second, slow CC (copper-carbon coupling) kinetics result in low ethanol selectivity, with Faraday efficiencies generally below 40%. Furthermore, complex side reaction pathways easily generate byproducts such as ethylene and acetic acid, increasing separation costs. Current research largely focuses on copper-based catalyst modification and electrolyte optimization, but achieving a balance between high ethanol selectivity and energy efficiency remains a bottleneck in acidic media due to HER competition and copper corrosion.

[0004] Therefore, developing a Cu-based catalyst with high activity, high stability and clearly defined active sites, and elucidating its mechanism for promoting CC coupling and directional ethanol generation, effectively promoting CO2RR under acidic conditions, has become a core issue that urgently needs to be addressed in this field. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a cationic polymer-coated copper-based catalyst, its preparation method, and its application. First, quaternized piperazine spirals are mixed with copper nanoparticles. The piperazine ring and amino functional groups in the quaternized piperazine spirals are tightly adsorbed onto the surface of the copper nanoparticles through coordination bonds. Then, a stable cationic polymer coating layer is formed on the surface of the copper nanoparticles through a crosslinking reaction of 1,3,5-benzenetricarboxylic acid chloride, effectively enhancing the catalyst's activity and stability in acidic environments. This cationic polymer-coated copper-based catalyst exhibits excellent carbon dioxide electrocatalytic reduction performance in an acidic electrolyzer through a three-pronged mechanism of "electrostatic enrichment-coordination stabilization-crosslinking enhancement," enabling efficient ethanol production at 250 mA / cm². 2 It achieves a Faraday efficiency of up to 50% at current densities.

[0006] The first objective of this invention is to provide a method for preparing a cationic polymer-coated copper-based catalyst, comprising the following steps:

[0007] Copper nanoparticles were added to a quaternized piperazine solution, stirred until homogeneous, and the pH was adjusted to 9-13. Then, a 1,3,5-benzenetricarboxyl chloride solution was added to carry out the reaction, thereby obtaining the copper-based catalyst coated with the cationic polymer.

[0008] In one embodiment of the present invention, the preparation of the quaternized spiroperazine includes the following steps:

[0009] A solution of di(2-chloroethyl)amine hydrochloride was added dropwise to a piperazine solution, followed by the addition of calcium carbonate to react and obtain the quaternized spiroperazine.

[0010] In one embodiment of the present invention, the concentration of the piperazine solution is 0.5 mol / L to 5 mol / L; the concentration of the di(2-chloroethyl)amine hydrochloride solution is 0.5 mol / L to 5 mol / L.

[0011] In one embodiment of the present invention, the volume ratio of the piperazine solution to the di(2-chloroethyl)amine hydrochloride solution is (1-3):5.

[0012] In one embodiment of the present invention, the reaction temperature is 52°C-58°C and the time is 8h-10h.

[0013] In one embodiment of the present invention, the mass fraction of the quaternized spiroperazine solution is 0.05%-5%; and the mass fraction of the 1,3,5-benzenetricarboxylic acid chloride solution is 0.01%-1%.

[0014] In one embodiment of the present invention, the mass ratio of the quaternized spiroperazine, copper nanoparticles and 1,3,5-benzenetricarboxyl chloride is 1:(0.5-5):(0.1-2).

[0015] In one embodiment of the present invention, the pH adjuster is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate. Adjusting the pH to 9-13 with the pH adjuster allows the crosslinking reaction of 1,3,5-benzenetriacyl chloride and quaternized piperazine to neutralize the HCl generated in the reaction under alkaline conditions, avoiding the inhibition of the reaction by HCl, ensuring efficient formation of amide bonds, and thus constructing a stable three-dimensional cationic polymer coating layer.

[0016] A second objective of this invention is to provide a copper-based catalyst coated with a cationic polymer prepared by the method described above.

[0017] A third objective of this invention is to provide an application of the aforementioned cationic polymer-coated copper-based catalyst in the catalysis of carbon dioxide in an acidic system.

[0018] In one embodiment of the present invention, the copper-based catalyst coated with a cationic polymer is loaded onto an electrode material and used as a working electrode in an electrolytic cell.

[0019] The technical solution of the present invention has the following advantages compared with the prior art:

[0020] (1) The preparation method of this invention uses 1,3,5-benzenetricarboxyl chloride as a trifunctional crosslinking agent. Its three acyl chloride groups can undergo condensation reactions with the amino groups in quaternized spiral piperazine to form a three-dimensional crosslinked network structure. This three-dimensional crosslinked network structure significantly enhances the mechanical strength and chemical stability of the coating layer, preventing it from swelling or peeling under acidic electrolytes or high current densities, thereby ensuring that the catalyst maintains its activity during long-term operation. The rigid structure and multi-amino coordination ability of spiral piperazine in quaternized spiral piperazine achieve stable coordination and precise electronic structure control on the surface of copper nanoparticles. In addition, the crosslinking effect of 1,3,5-benzenetricarboxyl chloride fixes the distribution of cationic groups in quaternized spiral piperazine, enabling it to maintain a stable charge distribution during dynamic electrolysis. This synergistic effect ensures the continuous enrichment of carbon dioxide and the stability of the local alkaline microenvironment.

[0021] (2) The quaternized piperazine spiral in the cationic polymer-coated copper-based catalyst of the present invention is a cationic polymer. Its quaternary ammonium groups carry a positive charge in acidic electrolytes and can attract negatively charged carbon dioxide molecules and their reduction intermediates through electrostatic interactions, thereby forming a locally high-concentration carbon dioxide microenvironment on the catalyst surface. This enrichment effect significantly improves the adsorption efficiency of carbon dioxide and inhibits H+ adsorption. + The competitive hydrogen evolution reaction (HER) creates favorable conditions for subsequent CC coupling.

[0022] (3) The cationic polymer-coated copper-based catalyst of this invention utilizes the piperazine ring and amino functional groups in the quaternized spiral piperazine to tightly bind to the surface of copper nanoparticles through coordination bonds. This coordination not only fixes the coating structure of the cationic polymer coating layer but also modulates the electronic structure of copper, making its surface active sites more inclined to stabilize *CO intermediates and promote the formation of CC coupling rather than single-carbon products (such as CO or formic acid). At the same time, the cationic polymer coating layer acts as a physical barrier, isolating the direct corrosion of copper nanoparticles by acidic media. Its cross-linked structure maintains its own stability, ensuring active sites and achieving continuous, efficient, and stable operation for 50 hours. In addition, the cationic polymer coating layer has a controllable pore structure, allowing carbon dioxide molecules and small-sized intermediates (such as *CO) to freely diffuse to the surface of copper nanoparticles, but restricting the formation pathway of larger by-products (such as ethylene and acetic acid). This selective mass transfer further optimizes the ethanol formation pathway and suppresses side reactions.

[0023] (4) The copper species in the cationic polymer-coated copper-based catalyst of the present invention exist in a mixed valence state of 0 and +2, with +2 being the predominant valence state. The mixed valence state of copper promotes carbon dioxide adsorption and activation through synergistic effects, while the presence of CuO helps stabilize the surface active sites. The cations in the quaternized piperazine spiral can form a locally micro-alkaline environment (pH≈9) on the catalyst surface, accelerating the proton-coupled electron transfer process of carbon dioxide and inhibiting H+. + The reduction (HER) promotes the carbon dioxide dissolution reaction, inhibits the hydrogen evolution reaction, and improves the selectivity of ethanol production.

[0024] (5) In the acidic system, the cationic polymer-coated copper-based catalyst of the present invention regulates the reaction microenvironment by regulating the cationic polymer coating layer, promoting carbon dioxide adsorption and activation, affecting the adsorption and desorption behavior of intermediates, making the reaction more likely to undergo the CC coupling reaction to produce ethanol, and suppressing side reactions at -250 mA / cm². 2 At current density, the Faraday efficiency reaches 50%, and it can operate continuously and efficiently for 50 hours, demonstrating good application results. Attached Figure Description

[0025] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0026] Figure 1 The X-ray diffraction pattern of Cu@QSPIP-TMC in Test Example 1 of this invention;

[0027] Figure 2 This is a scanning electron microscope image of Cu@QSPIP-TMC in Test Example 1 of this invention;

[0028] Figure 3 This is a transmission electron microscope (TEM) image of Cu@QSPIP-TMC in Test Example 1 of this invention;

[0029] Figure 4 The total current density-potential curve of the electrocatalytic carbon dioxide reduction reaction in Test Example 2 of this invention;

[0030] Figure 5 The diagram shows the Faradaic efficiency of each product under different potentials in the electrocatalytic carbon dioxide reduction reaction of the catalyst in Test Example 3 of this invention; where the left diagram is Cu@QSPIP-TMC, the middle diagram is Cu@PIP-TMC, and the right diagram is Cu.

[0031] Figure 6 This is a Faraday efficiency diagram of the products at different carbon dioxide gas flow rates during the Cu@QSPIP-TMC electrocatalytic carbon dioxide reduction reaction in Test Example 4 of this invention.

[0032] Figure 7 The cathode potential-time curves and Faraday efficiency-time curves of each product in the Cu@QSPIP-TMC electrocatalytic carbon dioxide reduction reaction in Test Example 5 of this invention are shown. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. It should be understood that the specific embodiments are only used to explain the present invention, but the embodiments are not intended to limit the present invention.

[0034] In this invention, unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0035] In this invention, unless otherwise stated, the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0036] In this invention, unless otherwise specified, the experimental methods used in the embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified. In this invention, unless otherwise specified,

[0037] In this invention, unless otherwise stated, the copper nanoparticles used in the embodiments of this invention have a particle size of approximately 60 nm to 100 nm.

[0038] Example 1

[0039] The cationic polymer-coated copper-based catalyst (Cu@QSPIP-TMC) and its preparation method of the present invention specifically include the following steps:

[0040] Preparation of S1, Quaternized Spiropiperazine (QSPIP)

[0041] S11. Preparation of piperazine solution: Dissolve 12g of piperazine in 60mL of deionized water to obtain a piperazine solution with a concentration of 1.25mol / L.

[0042] S12. Preparation of di(2-chloroethyl)amine hydrochloride solution: Dissolve 27.4g of di(2-chloroethyl)amine hydrochloride in 150mL of deionized water to obtain a di(2-chloroethyl)amine hydrochloride solution with a concentration of 1.02mol / L.

[0043] S13. Preparation of Quaternized Spiropiperazine (QSPIP): Di(2-chloroethyl)amine hydrochloride solution was added dropwise to piperazine solution, followed by the addition of 14.8 g of calcium carbonate. The mixture was refluxed at 55 °C for 9 h. After filtering to remove the white precipitate, the mixture was concentrated by rotary evaporation, precipitated in ethanol, filtered, and washed three times with ethanol. Finally, the mixture was vacuum dried at 50 °C for 8 h to obtain quaternized spirropiperazine (QSPIP).

[0044] S2. Preparation of cationic polymer-coated copper-based catalyst (Cu@QSPIP-TMC)

[0045] S21. Preparation of quaternized spiroperazine solution: Dissolve 2g of quaternized spiroperazine in 400mL of deionized water to form a quaternized spiroperazine solution with a mass fraction of 0.5%.

[0046] Preparation of S22, 1,3,5-benzoyl chloride solution: Dissolve 0.4 g of 1,3,5-benzoyl chloride (TMC) in 400 mL of deionized water to obtain a 0.1% (w / w) 1,3,5-benzoyl chloride solution;

[0047] S23. Preparation of cationic polymer-coated copper-based catalyst (Cu@QSPIP-TMC): 1.2 g of copper nanoparticles were added to a quaternized piperazine solution and stirred until homogeneous. The pH was adjusted to 11 using sodium hydroxide. Then, a 1,3,5-benzenetriformyl chloride solution was added to initiate the reaction. The precipitate was filtered, and the resulting precipitate was washed three times with hexane, three times with water, three times with ethanol, and three times with water to obtain the cationic polymer-coated copper-based catalyst (Cu@QSPIP-TMC).

[0048] Comparative Example 1

[0049] Basically the same as Example 1, except that the cation is not modified, and specifically includes the following steps:

[0050] Preparation of S1 and Spiropiperazine (PIP)

[0051] S11. Preparation of piperazine solution: Dissolve 12g of piperazine in 60mL of deionized water to obtain a piperazine solution with a concentration of 1.25mol / L.

[0052] S12. Preparation of Spiropiperazine (PIP): 14.8 g of calcium carbonate was added to the piperazine solution and refluxed at 55 °C for 9 h. After filtering to remove the white precipitate, the solution was concentrated by rotary evaporation, precipitated in ethanol, filtered, and washed three times with ethanol. Finally, the solution was dried under vacuum at 50 °C for 8 h to obtain spirropiperazine (PIP).

[0053] S2. Preparation of polymer-coated copper-based catalyst (Cu@PIP-TMC)

[0054] S21. Preparation of Spiropiperazine Solution: Dissolve 2g of spiropiperazine in 400mL of deionized water to form a spiropiperazine solution with a mass fraction of 0.5%.

[0055] Preparation of S22, 1,3,5-benzoyl chloride solution: Dissolve 0.4 g of 1,3,5-benzoyl chloride (TMC) in 400 mL of deionized water to obtain a 0.1% (w / w) 1,3,5-benzoyl chloride solution;

[0056] S23. Preparation of polymer-coated copper-based catalyst (Cu@PIP-TMC): 1.2 g of copper nanoparticles were added to a spiroperazine solution and stirred until homogeneous. The pH was adjusted to 11 using sodium hydroxide. Then, a 1,3,5-benzenetricarboxyl chloride solution was added to initiate the reaction. The precipitate was filtered, and the resulting precipitate was washed three times with hexane, three times with water, three times with ethanol, and three times with water to obtain the polymer-coated copper-based catalyst (Cu@PIP-TMC).

[0057] Comparative Example 2

[0058] Copper nanoparticles (Cu).

[0059] Test Example 1

[0060] The phase composition of the cationic polymer-coated copper-based catalyst (Cu@QSPIP-TMC) prepared in Example 1 was analyzed using X-ray diffraction (XRD). The scanning range was 2θ = 10°–90° with a step size of 0.02°. The reference standard was the JCPDS standard card (Cu: 04-0836, CuO: 48-1548). The results are as follows: Figure 1 As shown. From Figure 1It can be seen that the main diffraction peaks correspond to Cu(0) (2θ = 43.3°, 50.4°) and CuO (2θ = 35.5°, 38.7°), indicating that the copper species exist in a mixed valence state of 0 and +2, mainly in the +2 valence state. The mixed valence state of copper promotes the adsorption and activation of carbon dioxide through synergistic effects, and the presence of CuO helps to stabilize the surface active sites.

[0061] The cationic polymer-coated copper-based catalyst (Cu@QSPIP-TMC) prepared in Example 1 was dispersed in ethanol. After ultrasonic treatment, it was respectively drop-coated on a silicon wafer and a carbon film copper mesh. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses were carried out using an instrument. The mapping of the surface element distribution of Cu@QSPIP-TMC was performed using the EDS detector attached to the SEM. The results are as Figures 2-3 shown. It can be seen from Figure 2 that Cu@QSPIP-TMC shows a granular agglomerated structure, and a uniform polymer film covers the surface. Moreover, the elements Cu, N, O, and Cl are evenly distributed, and the presence of N and Cl confirms the successful loading of the cationic polymer. The cationic polymer can attract carbon dioxide molecules through electrostatic attraction, forming a local high-concentration carbon dioxide microenvironment and promoting C-C coupling. Figure 3 It is further confirmed that the copper nanoparticles are wrapped by the cationic polymer. The cationic polymer coating layer effectively prevents the aggregation of copper particles and enriches carbon dioxide molecules through electrostatic interaction, improving the mass transfer efficiency.

[0062] Test Example 2

[0063] The catalysts prepared in Example 1 and Comparative Examples 1-2 were respectively mixed with isopropanol at a ratio of [5mg:1mL] to form a dispersion; then a 100 μL pipette was used to drop the dispersion on a carbon paper (model 28BC) with an area of 1.44 cm 2 . It was dried in an incubator at 60 °C for 2 h, and finally bonded with a fluororubber gasket compatible with the flow cell to obtain a working electrode with a catalyst loading of 1 mg / cm 2 , which were respectively denoted as Cu@QSPIP-TMC / CFP, Cu@PIP-TMC / CFP, and Cu / CFP;

[0064] In the flow cell, using Cu@QSPIP-TMC / CFP and Cu / CFP as working electrodes, an Ir / Ti mesh as the counter electrode, and Ag / AgCl as the reference electrode, with an electrolyte of 0.05 mol / L H2SO4 + 0.5 mol / L KCl, a carbon dioxide flow rate of 50 sccm, and a scanning rate of 5 mV / s, the electrocatalytic carbon dioxide reduction reaction was carried out. The total current density-potential curve is as Figure 4 shown. It can be seen from Figure 4It can be seen that the Cu@QSPIP-TMC of Example 1 can achieve an electrolytic cell operation of 250 mA / cm² at a potential of -2V (relative to the reference electrode). 2 The current density was significantly higher than that of copper nanoparticles in Comparative Example 2. This indicates that the cationic polymer coating reduces the HER competition reaction and increases the current density of CO2RR.

[0065] Test Example 3

[0066] In a flow cell, Cu@QSPIP-TMC / CFP, Cu@PIP-TMC / CFP, and Cu / CFP were used as working electrodes, Ir / Ti mesh as counter electrodes, and Ag / AgCl as reference electrodes. Two 20 mL solutions of 0.05 mol / L H₂SO₄ + 0.5 mol / L KCl were used as the cathode electrolyte and anolyte, respectively. The carbon dioxide flow rate was 50 sccm, and the electrolyte flow rate was 20 cm⁻¹. 3 The electrocatalytic carbon dioxide reduction reaction was carried out at a current density of -100 mA / cm². The test employed a constant current polarization method, applying a negative current to achieve a current density of -100 mA / cm². 2 -200mA / cm 2 -250mA / cm 2 -300mA / cm 2 -400mA / cm 2 The gaseous products of the reaction were detected in real time by gas chromatography (GC detection), and the liquid products were detected by nuclear magnetic resonance spectroscopy (1H NMR analysis). The Faraday efficiency of each product at different potentials is shown in the figure. Figure 5 As shown. From Figure 5 It can be seen that at -250mA / cm 2 In Example 1, the ethanol FE was approximately 45%-50%, while in Comparative Example 1 it was approximately 20%-25%, and in Comparative Example 2 it was approximately 10%-15%. The selectivity for other products (such as ethylene and acetic acid) was also significantly reduced. This is because the cationic polymer inhibits HER through a locally alkaline environment (pH≈9); stabilizes the *CO intermediate, promotes CC coupling; and restricts the formation pathway of byproducts (such as ethylene) due to steric hindrance.

[0067] Test Example 4

[0068] Based on the above experiments, the current density was fixed at -250 mA / cm². 2 By varying the carbon dioxide flow rate from 2 sccm to 50 sccm, the product selectivity of the Cu@QSPIP-TMC electrocatalyzed carbon dioxide reduction reaction under different carbon dioxide gas flow rates was investigated. The results are as follows: Figure 6 As shown. From Figure 6It can be seen that when the carbon dioxide flow rate is 40 sccm, the Faradaic efficiency for products such as ethylene, ethanol, and acetic acid reaches 78%, indicating that Cu@QSPIP-TMC has high selectivity for these products under this condition. This is because excessively high flow rates result in insufficient residence time of carbon dioxide on the Cu@QSPIP-TMC surface, while excessively low flow rates lead to mass transfer limitations.

[0069] Test Example 5

[0070] Based on the above experiments, at a current density of -250 mA / cm² 2 Under these conditions, the system was continuously run for 50 hours, with hourly sampling to analyze product distribution. The stability of Cu@QSPIP-TMC was tested, and cathode potential-time curves and Faraday efficiency-time curves for each product were obtained. The results are as follows: Figure 7 As shown. From Figure 7 It can be seen that after 10 hours, the cathode potential fluctuation was less than ±50mV, and the ethanol FE remained above 37% without significant decay. This indicates that Cu@QSPIP-TMC has excellent stability, because the cationic polymer coating effectively protects the copper surface from acid corrosion while maintaining the stability of the active sites.

[0071] 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 a cationic polymer-coated copper-based catalyst, characterized in that, Includes the following steps: Copper nanoparticles were added to a quaternized piperazine solution, stirred until homogeneous, and the pH was adjusted to 9-13. Then, a 1,3,5-benzenetricarboxyl chloride solution was added to carry out the reaction, thereby obtaining the copper-based catalyst coated with the cationic polymer. The preparation of the quaternized spiroperazine includes the following steps: adding di(2-chloroethyl)amine hydrochloride solution dropwise to a piperazine solution, and then adding calcium carbonate to react and obtain the quaternized spiroperazine.

2. The method for preparing the cationic polymer-coated copper-based catalyst according to claim 1, characterized in that, The concentration of the piperazine solution is 0.5 mol / L to 5 mol / L; the concentration of the di(2-chloroethyl)amine hydrochloride solution is 0.5 mol / L to 5 mol / L.

3. The method for preparing the cationic polymer-coated copper-based catalyst according to claim 1, characterized in that, The volume ratio of the piperazine solution to the di(2-chloroethyl)amine hydrochloride solution is (1-3):

5.

4. The method for preparing the cationic polymer-coated copper-based catalyst according to claim 1, characterized in that, The reaction was carried out at a temperature of 52℃-58℃ for 8-10 hours.

5. The method for preparing the cationic polymer-coated copper-based catalyst according to claim 1, characterized in that, The mass fraction of the quaternized piperazine spirohydrin solution is 0.05%-5%; the mass fraction of the 1,3,5-benzenetricarboxyl chloride solution is 0.01%-1%.

6. The method for preparing the cationic polymer-coated copper-based catalyst according to claim 1, characterized in that, The mass ratio of the quaternized piperazine spiral, copper nanoparticles and 1,3,5-benzenetricarboxyl chloride is 1:(0.5-5):(0.1-2).

7. The method for preparing the cationic polymer-coated copper-based catalyst according to claim 1, characterized in that, The pH adjuster is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate.

8. A copper-based catalyst coated with a cationic polymer prepared by the preparation method according to any one of claims 1-7.

9. The application of the cationic polymer-coated copper-based catalyst of claim 8 in the catalysis of carbon dioxide in an acidic system.

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