Cationic polymer coated copper-based catalyst as well as preparation method and application thereof

Abstract

The invention relates to a cationic polymer coated copper-based catalyst as well as a preparation method and application thereof, and belongs to the technical field of catalysts. The preparation method comprises the following steps: adding copper nanoparticles into a quaternized spiropiperazine solution, uniformly stirring, adjusting the pH value to 9-13, and then adding a 1, 3, 5-benzoyl chloride solution for reaction to obtain the copper-based catalyst coated with the cationic polymer. The copper-based catalyst coated with the cationic polymer shows excellent carbon dioxide electrocatalytic reduction performance in an electrolytic tank under the acidic condition through a three-in-one mechanism of electrostatic enrichment, coordination stabilization and cross-linking strengthening, ethanol can be efficiently prepared, and the Faraday efficiency reaching up to 50% is achieved under the current density of 250 mA / cm < 2 >.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and in particular relates to a cationic polymer-coated copper-based catalyst and a preparation method and application thereof. Background Art

[0002] In recent years, with the advancement of global carbon neutrality goals, electrocatalytic carbon dioxide reduction (CO 2 The electrocatalytic reduction of carbon dioxide to multi-carbon products (such as ethylene, ethanol, propanol, etc.) is considered a key path to achieve the recycling of carbon resources. 2 H 5 OH) is a high-energy-density liquid fuel and an important chemical raw material. Its efficient synthesis can alleviate the problems of energy shortage and carbon emission at the same time, and has significant economic and environmental benefits.

[0003] Existing electrocatalytic systems face many challenges in producing ethanol under acidic conditions. First, the HER competition is severe in acidic environments, resulting in CO 2 RR efficiency is low, catalysts are easily deactivated, and mass transfer is difficult. Secondly, CC coupling kinetics are slow, ethanol selectivity is low, and Faraday efficiency is generally less than 40%. In addition, the side reaction pathways are complex, and byproducts such as ethylene and acetic acid are easily generated, which increases the separation cost. Existing research focuses on copper-based catalyst modification and electrolyte optimization, but it is difficult to achieve a balance between high ethanol selectivity and energy efficiency in acidic media due to HER competition and copper corrosion.

[0004] Therefore, a Cu-based catalyst with high activity, high stability and clear active sites was developed, and its mechanism of promoting CC coupling and directional ethanol production was elucidated, which effectively promoted CO under acidic conditions. 2 RR has become a core issue that needs to be solved urgently in this field. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a cationic polymer-coated copper-based catalyst and its preparation method and application. First, quaternized spiropiperazine is mixed with copper nanoparticles. The piperazine ring and amino functional group in the quaternized spiropiperazine can be closely adsorbed to 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 the cross-linking reaction of 1,3,5-benzenetricarboxylic acid chloride, which can effectively improve the activity and stability of the catalyst in an acidic environment. The cationic polymer-coated copper-based catalyst exhibits excellent carbon dioxide electrocatalytic reduction performance in an electrolytic cell under acidic conditions through the trinity mechanism of "electrostatic enrichment-coordination stabilization-cross-linking reinforcement", and can efficiently prepare ethanol. At 250mA / cm 2A Faradaic efficiency of up to 50% was achieved at a current density of 1.5 %.

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

[0007] Copper nanoparticles are added to the quaternized spiropiperazine solution, stirred evenly, and the pH is adjusted to 9-13, and then 1,3,5-benzenetricarboxylic acid chloride solution is added to react to obtain the cationic polymer-coated copper-based catalyst.

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

[0009] The di(2-chloroethyl)amine hydrochloride solution is added dropwise to the piperazine solution, and then calcium carbonate is added to react to obtain the quaternized spiropiperazine.

[0010] In one embodiment of the present invention, the concentration of the piperazine solution is 0.5 mol / L-5 mol / L; the concentration of the di(2-chloroethyl)amine hydrochloride solution is 0.5 mol / L-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 reaction time is 8 h-10 h.

[0013] In one embodiment of the present invention, the mass fraction of the quaternized spiropiperazine solution is 0.05%-5%; 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 spiropiperazine, the copper nanoparticles and 1,3,5-benzenetricarboxylic acid chloride is 1:(0.5-5):(0.1-2).

[0015] In one embodiment of the present invention, the pH regulator is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate and sodium bicarbonate. The pH is adjusted to 9-13 by the pH regulator, so that the cross-linking reaction of 1,3,5-benzenetricarboxylic acid chloride and quaternized spiropiperazine can neutralize the HCl generated by the reaction in an alkaline environment, avoid the inhibition of the reaction by HCl, ensure the efficient formation of amide bonds, and thus construct a stable three-dimensional cationic polymer coating layer.

[0016] The second object of the present invention is to provide a cationic polymer-coated copper-based catalyst prepared by the preparation method.

[0017] The third object of the present invention is to provide an application of the cationic polymer-coated copper-based catalyst in catalyzing carbon dioxide in an acidic system.

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

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

[0020] (1) The preparation method described in the present invention uses 1,3,5-benzenetricarboxylic acid chloride as a trifunctional cross-linking agent, and its three acyl chloride groups can undergo condensation reaction with the amino groups in the quaternized spiropiperazine to form a three-dimensional cross-linked network structure. This three-dimensional cross-linked network structure significantly enhances the mechanical strength and chemical stability of the coating layer, preventing it from swelling or peeling off in acidic electrolytes or at high current densities, thereby ensuring that the catalyst remains active during long-term operation. The rigid structure and multi-amino coordination ability of the spiropiperazine in the quaternized spiropiperazine achieve stable coordination and precise electronic structure regulation on the surface of copper nanoparticles. In addition, the cationic group distribution of the quaternized spiropiperazine is fixed by the cross-linking effect of 1,3,5-benzenetricarboxylic acid chloride, so that it can still 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 spiropiperazine in the cationic polymer-coated copper-based catalyst of the present invention is a cationic polymer, and its quaternary ammonium group carries a positive charge in the acidic electrolyte, which can attract negatively charged carbon dioxide molecules and their reduction intermediates through electrostatic action, thereby forming a local high-concentration carbon dioxide microenvironment on the catalyst surface. This enrichment effect significantly improves the adsorption efficiency of carbon dioxide and inhibits H + The competitive hydrogen evolution reaction (HER) creates favorable conditions for the subsequent CC coupling.

[0022] (3) The cationic polymer-coated copper-based catalyst described in the present invention utilizes the piperazine ring and amino functional group in the quaternized spiropiperazine to tightly bind to the surface of the copper nanoparticles through coordination bonds. This coordination effect not only fixes the coating structure of the cationic polymer coating layer, but also adjusts the electronic structure of copper, making its surface active sites more inclined to stabilize the *CO intermediate, promoting CC coupling rather than the generation of single-carbon products (such as CO or formic acid). At the same time, the cationic polymer coating layer acts as a physical barrier to isolate the direct corrosion of the copper nanoparticles by the acidic medium, and its cross-linked structure maintains its own stability, ensures the active sites, and achieves 50 hours of continuous, efficient and stable operation. In addition, the cationic polymer coating layer has a controllable pore structure, allowing carbon dioxide molecules and small-sized intermediates (such as *CO) to diffuse freely to the surface of the copper nanoparticles, but restricts the generation path of larger byproducts (such as ethylene and acetic acid). This selective mass transfer further optimizes the generation path of ethanol and inhibits side reactions.

[0023] (4) The copper species in the cationic polymer-coated copper-based catalyst of the present invention exists in a mixed valence state of 0 and +2, with +2 being the main valence. 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. The cations in the quaternized spiropiperazine can form a local slightly alkaline environment (pH ≈ 9) on the catalyst surface, accelerating the proton-coupled electron transfer process of carbon dioxide and inhibiting the H + reduction (HER), thereby promoting the carbon dioxide dissolution reaction, inhibiting the hydrogen evolution reaction, and improving the selectivity of ethanol production.

[0024] (5) When the cationic polymer-coated copper-based catalyst of the present invention catalyzes carbon dioxide to prepare multi-carbon products in an acidic system, the cationic polymer coating layer regulates the reaction microenvironment, promotes carbon dioxide adsorption and activation, affects the adsorption and desorption behavior of the intermediate, makes the reaction more prone to CC coupling reaction to produce ethanol, inhibits side reactions, and 2 The Faraday efficiency reaches 50% under the current density, and it can operate continuously and efficiently for 50 hours, showing good application effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

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

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

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

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

[0030] Figure 5 The Faraday efficiency diagram of each product at different potentials in the electrocatalytic carbon dioxide reduction reaction of the catalyst in Test Example 3 of the present invention; wherein the left figure is Cu@QSPIP-TMC, the middle figure is Cu@PIP-TMC, and the right figure is Cu;

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

[0032] Figure 7 The cathode potential-time curve and the Faraday efficiency-time curve of each product of the Cu@QSPIP-TMC electrocatalytic carbon dioxide reduction reaction in Test Example 5 of the present invention. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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 the present invention, unless otherwise explained, technical and scientific terms used in the present invention have the same meanings as commonly understood by those skilled in the art to which the present invention belongs.

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

[0036] In the present invention, unless otherwise specified, the experimental methods used in the examples of the present invention are conventional methods unless otherwise specified, and the materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial channels. In the present invention, unless otherwise specified,

[0037] In the present invention, unless otherwise specified, the particle size of the copper nanoparticles used in the embodiments of the present invention is about 60 nm-100 nm.

[0038] Example 1

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

[0040] S1. Preparation of quaternized spiropiperazine (QSPIP)

[0041] S11, preparation of piperazine solution: dissolving 12 g of piperazine in 60 mL of deionized water to obtain a piperazine solution with a concentration of 1.25 mol / L;

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

[0043] S13. Preparation of quaternized spiropiperazine (QSPIP): Di(2-chloroethyl)amine hydrochloride solution was added dropwise to the piperazine solution, and then 14.8 g of calcium carbonate was added. The mixture was refluxed at 55° C. for 9 h, and the white precipitate was removed by filtration. 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 spiropiperazine (QSPIP).

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

[0045] S21, preparation of quaternized spiropiperazine solution: dissolving 2 g of quaternized spiropiperazine in 400 mL of deionized water to form a quaternized spiropiperazine solution with a mass fraction of 0.5%;

[0046] S22, preparation of 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% mass fraction 1,3,5-benzoyl chloride solution;

[0047] S23. Preparation of cationic polymer-coated copper-based catalyst (Cu@QSPIP-TMC): Add 1.2 g of copper nanoparticles to the quaternized spiropiperazine solution and stir evenly, and adjust the pH to 11 with sodium hydroxide; then add 1,3,5-benzenetricarboxylic acid chloride solution to react, filter the precipitate, and wash the precipitate with hexane 3 times, water 3 times, ethanol 3 times, and water 3 times to obtain a cationic polymer-coated copper-based catalyst (Cu@QSPIP-TMC).

[0048] Comparative Example 1

[0049] The method is basically the same as Example 1, except that the cation is not modified, and specifically comprises the following steps:

[0050] S1. Preparation of spiropiperazine (PIP)

[0051] S11, preparation of piperazine solution: dissolve 12 g of piperazine in 60 mL of deionized water to obtain a piperazine solution with a concentration of 1.25 mol / L;

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

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

[0054] S21, preparation of spiropiperazine solution: dissolving 2 g of spiropiperazine in 400 mL of deionized water to form a spiropiperazine solution with a mass fraction of 0.5%;

[0055] S22, preparation of 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% mass fraction 1,3,5-benzoyl chloride solution;

[0056] S23. Preparation of polymer-coated copper-based catalyst (Cu@PIP-TMC): Add 1.2 g of copper nanoparticles to the spiropiperazine solution and stir evenly, and adjust the pH to 11 with sodium hydroxide; then add 1,3,5-benzenetricarboxylic acid chloride solution to react, filter the precipitate, and wash the precipitate with hexane 3 times, water 3 times, ethanol 3 times, and water 3 times to obtain a polymer-coated copper-based catalyst (Cu@PIP-TMC).

[0057] Comparative Example 2

[0058] Copper nanoparticles (Cu).

[0059] Test Example 1

[0060] The cationic polymer-coated copper-based catalyst (Cu@QSPIP-TMC) prepared in Example 1 was subjected to phase analysis using an X-ray diffractometer, with a scanning range of 2θ=10°~90° and a step length 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. 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 exists in a mixed valence state of 0 and +2, with +2 being the main valence. 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, and after ultrasonic treatment, it was drop-coated on a silicon wafer and a carbon film copper mesh, respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for analysis, and the surface element distribution of Cu@QSPIP-TMC was mapped using the EDS detector attached to the SEM. The results are as follows: Figure 2-Figure 3 As shown. Figure 2 It can be seen that Cu@QSPIP-TMC has a granular agglomerated structure with a uniform polymer film on the surface. The Cu, N, O, and Cl elements 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 electrostatics, forming a local high-concentration carbon dioxide microenvironment and promoting CC coupling. Figure 3 It was further confirmed that the copper nanoparticles were encapsulated by cationic polymers. The cationic polymer coating effectively prevented the copper particles from agglomerating, while enriching carbon dioxide molecules through electrostatic action and improving mass transfer efficiency.

[0062] Test Example 2

[0063] The catalysts prepared in Example 1 and Comparative Examples 1-2 were mixed with isopropanol at a ratio of 5 mg:1 mL to form a dispersion; then the dispersion was dropped onto a 1.44 cm 2 The catalyst was placed on carbon paper (model 28BC), dried in a constant temperature oven at 60 °C for 2 h, and finally bonded to the fluororubber gasket of the flow cell to obtain a catalyst loading of 1 mg / cm 2 The working electrodes are denoted as Cu@QSPIP-TMC / CFP, Cu@PIP-TMC / CFP, and Cu / CFP, respectively;

[0064] In the flow cell, Cu@QSPIP-TMC / CFP and Cu / CFP were used as working electrodes, Ir / Ti mesh was used as counter electrode, Ag / AgCl was used as reference electrode, and the electrolyte was 0.05 mol / L H 2 SO 4 +0.5mol / LKCl, carbon dioxide flow rate of 50sccm, scan rate of 5mV / s, electrocatalytic carbon dioxide reduction reaction, the total current density-potential curve is as follows Figure 4 As shown. Figure 4It can be seen that the Cu@QSPIP-TMC of Example 1 can reach 250 mA / cm at a potential of -2 V (relative to the reference electrode). 2 , which is significantly higher than the copper nanoparticles in Comparative Example 2. This indicates that the cationic polymer coating layer reduces the HER competitive reaction and improves CO 2 Current density of RR.

[0065] Test Example 3

[0066] In the flow cell, Cu@QSPIP-TMC / CFP, Cu@PIP-TMC / CFP, and Cu / CFP were used as working electrodes, Ir / Ti mesh was used as counter electrode, and Ag / AgCl was used as reference electrode. Two 20 mL 0.05 mol / L H 2 SO 4 +0.5mol / L KCl was used as the cathode electrolyte and the anode electrolyte, respectively, the carbon dioxide flow rate was 50sccm, and the electrolyte flow rate was 20cm 3 / min, and electrocatalytic carbon dioxide reduction reaction was carried out. The test adopted constant current polarization method, applying negative current and making the current density -100mA / cm 2 、-200mA / cm 2 、-250mA / cm 2 、-300mA / cm 2 、-400mA / cm 2 The gas phase products of the reaction are detected in real time by gas chromatography (GC detection), and the liquid phase products of the reaction are detected by nuclear magnetic resonance spectrometer (1HNMR analysis). The Faraday efficiency of each product under different potentials is as follows: Figure 5 As shown. Figure 5 It can be seen that at -250mA / cm 2 When the ethanol FE of Example 1 is about 45%-50%, the ethanol FE of Comparative Example 1 is about 20%-25%, and the ethanol FE of Comparative Example 2 is about 10%-15%. The selectivity of other products (such as ethylene and acetic acid) is also significantly reduced. This is because the cationic polymer inhibits HER through the local alkaline environment (pH≈9); stabilizes the *CO intermediate and promotes CC coupling; and the steric hindrance effect limits the generation path of by-products (such as ethylene).

[0067] Test Example 4

[0068] Based on the above experiments, the fixed current density is -250mA / cm 2 The carbon dioxide flow rate was changed from 2 sccm to 50 sccm to explore the product selectivity of Cu@QSPIP-TMC electrocatalytic carbon dioxide reduction reaction at different carbon dioxide gas flow rates. The results are as follows Figure 6 As shown. Figure 6 It can be seen that when the carbon dioxide flow rate is 40 sccm, the Faraday efficiency of ethylene, ethanol, acetic acid and other products reaches 78%, indicating that under this condition, Cu@QSPIP-TMC has a high selectivity for ethylene, ethanol, acetic acid and other products. This is because too high a flow rate causes insufficient residence time of carbon dioxide on the Cu@QSPIP-TMC surface, while too low a flow rate causes mass transfer limitation.

[0069] Test Example 5

[0070] Based on the above experiments, at a current density of -250mA / cm 2 The system was run continuously for 50 h under the same conditions, and samples were taken every hour to analyze the product distribution. The stability of Cu@QSPIP-TMC, cathode potential-time curve and Faraday efficiency-time curve of each product were tested. The results are shown in Figure 7 As shown. Figure 7 It can be seen that after 10 h, the cathode potential fluctuation is less than ±50 mV, and the ethanol FE is always maintained above 37% without obvious attenuation, which shows that Cu@QSPIP-TMC has excellent stability, because the cationic polymer coating can effectively protect the copper surface from acid corrosion while maintaining the stability of the active sites.

[0071] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A method for preparing a cationic polymer-coated copper-based catalyst, characterized in that: The following steps are involved: Copper nanoparticles are added to the quaternized spiropiperazine solution, stirred evenly, and the pH is adjusted to 9-13, and then 1,3,5-benzenetricarboxylic acid chloride solution is added to react to obtain the cationic polymer-coated copper-based catalyst.

2. The method for preparing a cationic polymer-coated copper-based catalyst according to claim 1, characterized in that: The preparation of the quaternized spiropiperazine comprises the following steps: The di(2-chloroethyl)amine hydrochloride solution is added dropwise to the piperazine solution, and then calcium carbonate is added to react to obtain the quaternized spiropiperazine.

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

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

5.

5. The method for preparing a cationic polymer-coated copper-based catalyst according to claim 2, characterized in that: The reaction temperature is 52°C-58°C and the reaction time is 8h-10h.

6. The method for preparing a cationic polymer-coated copper-based catalyst according to claim 1, characterized in that: The mass fraction of the quaternized spiropiperazine solution is 0.05%-5%; the mass fraction of the 1,3,5-benzenetricarboxylic acid chloride solution is 0.01%-1%.

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

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

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

10. Use of the cationic polymer-coated copper-based catalyst according to claim 9 in catalyzing carbon dioxide in an acidic system.

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