Cu single-site coordination polymer catalyst as well as preparation method and application thereof

Abstract

The invention provides a Cu single-site coordination polymer catalyst as well as a preparation method and application thereof, and the Cu single-site coordination polymer catalyst is obtained by carrying out coordination polymerization reaction on 2-methylimidazole serving as a ligand and bivalent copper salt by adopting a hydrothermal method. The Cu single-site coordination polymer catalyst disclosed by the invention has the advantages of good catalytic activity and high acetic acid selectivity in preparation of acetic acid by electroreduction of carbon monoxide.

Description

Technical Field

[0001] This invention relates to the field of energy catalysis technology, and in particular to a Cu single-site coordination polymer catalyst, its preparation method and application. Background Technology

[0002] The electroreduction of carbon monoxide (CMOS) has opened up a promising avenue for the manufacture of high-value-added multi-carbon products. The multi-carbon products of CMOS include acetic acid, ethylene, ethanol, and n-propanol. Acetic acid, in particular, has a global annual production exceeding 18 million tons and an annual market value of US$13 billion, with widespread applications in polymers, pharmaceuticals, and food. The electrocatalytic reduction of CMOS to acetic acid is also one of the most promising processes for industrial-scale production. The development of highly efficient catalysts is currently a key factor in the development of the CMOS electrocatalytic reduction to acetic acid process. Due to their suitable binding strength to adsorbed carbon monoxide and hydrogen species, Cu-based nanomaterials are commonly used electrocatalysts for the conversion of CMOS to acetic acid. However, limited by the variable configurations of intermediates and the complexity of the reaction network, currently available Cu-based catalysts generally exhibit poor selectivity and low current density, making it difficult to meet the demands of industrial applications. Summary of the Invention

[0003] Based on the technical problems existing in the background technology, the present invention proposes a Cu unit site coordination polymer catalyst, its preparation method and application. The catalyst has the advantages of good catalytic activity and high acetic acid selectivity in the electroreduction of carbon monoxide to prepare acetic acid.

[0004] This invention proposes a Cu single-site coordination polymer catalyst, which is obtained by using 2-methylimidazole as a ligand and divalent copper salt in a hydrothermal coordination polymerization reaction.

[0005] Traditional metal-organic framework compounds are mostly mesh-like porous structures, while in this invention, the Cu unit-point coordination polymers are all chain-like structures. The higher-order structure can be more easily controlled by changing the steric hindrance of the side groups, thereby adjusting the stability of the Cu unit-point structure.

[0006] Compared with conventional copper-based coordination polymers, the Cu single-site coordination polymer of this invention has replaceable side groups and adjustable interchain spacing, thereby controlling the stability of the higher-order structure. Among them, the 2-methylimidazole modified Cu-mim has the most stable Cu single-site structure and will not agglomerate and precipitate Cu particles under CO electroreduction conditions, thus exhibiting the best CO electroreduction performance for acetic acid production. In contrast, existing Cu-based coordination polymers are unstable under high current densities, and the Cu single-site structure easily transforms into Cu particles, resulting in limited selectivity.

[0007] Preferably, the Cu unit-point coordination polymer catalyst belongs to the triclinic crystal system, with cell parameters a = 17.061 Å, b = 11.299 Å, c = 8.3845 Å. , , .

[0008] Preferably, the divalent copper salt is at least one of Cu(NO3)2·3H2O, CuCl2·2H2O, CuSO4, or Cu2(OH)2CO3.

[0009] Preferably, the molar ratio of 2-methylimidazole to divalent copper salt is 1 to 2:1.

[0010] The present invention also proposes a method for preparing the above-mentioned Cu single-site coordination polymer catalyst, comprising: dissolving 2-methylimidazole and divalent copper salt in ammonia water, and then placing the resulting solution in a hydrothermal reactor for hydrothermal reaction to obtain the Cu single-site coordination polymer catalyst.

[0011] In the specific operation process, the divalent copper salt and 2-methylimidazole are first dissolved in ammonia water at room temperature and pressure, and a homogeneous solution is formed by magnetic stirring. The magnetic stirring time is preferably 15 to 60 min, more preferably 20 to 40 min, such as 20 min, 30 min, 40 min, and preferably any of the above values ​​as the upper or lower limit. In the specific operation process, the ammonia water can be formed by mixing concentrated ammonia water and water. The volume of ammonia water used is preferably 4 to 14 mL, more preferably 5 to 12 mL; the volume of water used is preferably 0 to 3 mL, more preferably 0 to 2 mL. In this invention, the homogeneous solution obtained above is transferred to a Teflon-lined stainless steel autoclave for hydrothermal reaction. Under high temperature and high pressure conditions, Cu ions and N atoms of 2-methylimidazole form a two-coordinate structure, with one Cu ion coordinating with two N atoms, alternately forming a long-chain coordination polymer.

[0012] Preferably, the hydrothermal reaction temperature is 150–170 °C and the time is 70–90 h.

[0013] Preferably, the preparation method further includes: centrifuging, washing, drying, and grinding the product obtained from the hydrothermal reaction.

[0014] In the specific operation process, the precipitate obtained from the hydrothermal reaction is centrifuged, washed, dried and ground to obtain Cu unit site coordination polymer catalyst. The grinding step is necessary because the precipitate particles are large in size and not easy to disperse ultrasonically, making it difficult to spray onto the carbon paper electrode in a uniform dispersion form. The precipitate particles are light yellow, and after grinding and standing for a period of time, a green powder is obtained. The washing needs to be performed three times with alternating ethanol and water, and the grinding time is at least 5 minutes.

[0015] This invention also proposes the application of the above-mentioned Cu single-site coordination polymer catalyst in the electroreduction of carbon monoxide to prepare acetic acid.

[0016] The application includes: in a flowing electrolytic cell, using the Cu unit-point coordination polymer catalyst as the working electrode, silver / silver chloride as the reference electrode, and a platinum sheet as the counter electrode, carbon monoxide is introduced into the working electrode, and a negative current is applied to carry out an electroreduction reaction to obtain acetic acid.

[0017] Preferably, the flow rate of carbon monoxide is 1–50 mL / min. -1 The electrolyte is at least one of potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium bicarbonate, or potassium bicarbonate solution, and the electrolyte concentration is 0.1–10 mol·L⁻¹. -1 The negative current is -100 to -1000 mA·cm. -2 .

[0018] In the specific operation process, the present invention uses a gas diffusion electrode loaded with the above-mentioned Cu unit-point coordination polymer catalyst as the working electrode, silver / silver chloride as the reference electrode, and a platinum sheet as the counter electrode to carry out an electrochemical reaction in a flow cell. The flow cell is divided into three chambers: an anode chamber, a cathode chamber, and a gas chamber. The anode chamber and the cathode chamber of the flow cell are separated by a Nafion 117 proton exchange membrane. The prepared gas diffusion electrode is sandwiched between the cathode chamber and the gas chamber, which is the catalytic reaction interface. Before starting the reaction, carbon monoxide is introduced into the gas chamber for 30 min to remove residual gas in the pipeline. Potassium hydroxide solution is added to the anode chamber and the cathode chamber as the electrolyte.

[0019] During the reaction, the carbon monoxide gas flow rate was set to 1–50 mL / min. -1 Preferably 20–30 mL·min -1 The electrolyte is potassium hydroxide, and the flow rate is set to 5–10 mL / min. -1 The applied total current density ranges from -100 to -1000 mA·cm. -2 Preferably -300 to -700 mA·cm -2The electrolysis time ranges from 150 to 300 seconds. During electrolysis, acetic acid will be continuously generated at the three-phase interface of the gas chamber, gas diffusion electrode, and cathode chamber.

[0020] Compared with the prior art, the present invention has the following beneficial effects: This invention modulates the chain spacing by replacing the side groups of the ligands in the coordination polymer, thereby controlling the polymer's higher-order structure and stabilizing the Cu single-site catalytic active structure at industrial-grade current densities, significantly improving the selectivity of CO electroreduction to acetic acid. Experimental results show that the Cu single-site coordination polymer catalyst can efficiently catalyze the conversion of carbon monoxide to acetic acid at industrial-grade current densities. The Cu single-site coordination polymer catalyst described in this invention has the advantages of good catalytic activity and high selectivity. Attached Figure Description

[0021] Figure 1 The image shown is a scanning electron microscope image of the Cu unit-site coordination polymer catalyst described in the embodiments of the present invention. Figure 2 The X-ray diffraction pattern of the Cu unit-point coordination polymer catalyst described in the embodiments of the present invention; Figure 3 The X-ray absorption near-edge structure spectrum of the Cu unit-site coordination polymer catalyst described in the embodiments of the present invention; Figure 4 The extended X-ray absorption fine structure spectrum of the Cu unit-site coordination polymer catalyst described in the embodiments of the present invention; Figure 5 This is a scanning electron microscope image of the Cu unit-site coordination polymer catalyst described in Comparative Example 1 of the present invention. Figure 6 The X-ray diffraction pattern of the Cu unit-point coordination polymer catalyst described in Comparative Example 1 of this invention; Figure 7 The X-ray absorption near-edge structure spectrum of the Cu unit-site coordination polymer catalyst described in Comparative Example 1 of this invention; Figure 8 The extended X-ray absorption fine structure spectrum of the Cu unit-site coordination polymer catalyst described in Comparative Example 1 of this invention; Figure 9 This is a scanning electron microscope image of the Cu unit-site coordination polymer catalyst described in Comparative Example 2 of the present invention; Figure 10 The X-ray diffraction pattern of the Cu unit-point coordination polymer catalyst described in Comparative Example 2 of this invention; Figure 11 The X-ray absorption near-edge structure spectrum of the Cu unit-site coordination polymer catalyst described in Comparative Example 2 of this invention; Figure 12The extended X-ray absorption fine structure spectrum of the Cu unit-site coordination polymer catalyst described in Comparative Example 2 of this invention; Figure 13 The Cu unit-site coordination polymer catalysts described in the embodiments and comparative examples of the present invention have acetic acid Faraday efficiencies at different current densities. Figure 14 The acetic acid bias current density of the Cu unit-site coordination polymer catalyst described in the embodiments and comparative examples of the present invention at different current densities; Figure 15 This is a performance comparison chart of the Cu single-site coordination polymer catalyst described in the embodiments of the present invention with other existing Cu single-site catalysts; Figure 16 This is the electrochemical in-situ extended X-ray absorption fine structure spectrum of the Cu unit site coordination polymer catalyst described in the embodiments of the present invention; Figure 17 This is the electrochemical in-situ extended X-ray absorption fine structure spectrum of the Cu unit-site coordination polymer catalyst described in Comparative Example 1 of the present invention; Figure 18 This is an electrochemical in-situ extended X-ray absorption fine structure spectrum of the Cu unit site coordination polymer catalyst described in Comparative Example 2 of the present invention. Detailed Implementation

[0022] The technical solution of the present invention will be described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0023] Example A Cu single-site coordination polymer catalyst is prepared by the following method: 2 mmol of commercially available Cu(NO3)2·3H2O and 2 mmol of 2-methylimidazole were dissolved in 10 mL of ammonia water. After magnetic stirring for 30 min, the resulting solution was transferred to a 25 mL Teflon-lined stainless steel autoclave and hydrothermally reacted at 160 °C for 80 h. The resulting precipitate was collected by centrifugation, washed three times alternately with ethanol and water, and then dried overnight. The resulting crystals were carefully ground for at least 5 min to obtain a methyl-modified Cu unit-site coordination polymer catalyst (denoted as Cu-mim). Cu-mim belongs to the triclinic crystal system with cell parameters a = 17.061 Å, b = 11.299 Å, c = 8.3845 Å. , , .

[0024] The scanning electron microscope images of the above Cu single-site coordination polymer catalysts are shown below. Figure 1 X-ray diffraction pattern seen Figure 2 X-ray absorption near-edge structure spectrum is shown in Figure 3 Extended X-ray absorption fine structure spectrum (see) Figure 4 .

[0025] Reference Figure 1 It can be seen that the Cu unit-site coordination polymer catalyst described in this embodiment has a micron-sized solid particle morphology.

[0026] Reference Figure 2 It can be seen that the X-ray diffraction pattern of the Cu unit site coordination polymer catalyst synthesized in this embodiment is in good agreement with the theoretical simulation results, indicating that the Cu unit site coordination polymer catalyst described in this embodiment is a long-chain polymer structure formed by Cu atoms bridging 2-methylimidazole.

[0027] Reference Figure 3 It can be seen that the spectral shape of the Cu single-site coordination polymer catalyst described in this embodiment is close to that of Cu2O, indicating that most Cu atoms in the Cu single-site coordination polymer catalyst have a monovalent oxidation state.

[0028] Reference Figure 4 It can be seen that the peak at 1.5 Å of the Cu unit site coordination polymer catalyst described in this embodiment belongs to the Cu-N bond; no obvious peaks belonging to the Cu-Cu bond were observed, proving that Cu atoms in the Cu unit site coordination polymer catalyst exist in the form of N-coordinated Cu unit sites.

[0029] As can be seen from the above, the catalyst obtained in this embodiment is a methyl-modified Cu single-site coordinated long-chain polymer.

[0030] Comparative Example 1 A Cu single-site coordination polymer catalyst is prepared by the following method: 0.5 mmol of commercially available Cu₂(OH)₂CO₃ and 1 mmol of 2-ethylimidazole were dissolved in a mixture of 5 mL ammonia and 2 mL water. After magnetic stirring for 30 min, the resulting solution was transferred to a 25 mL Teflon-lined stainless steel autoclave and hydrothermally reacted at 160 °C for 80 h. The resulting precipitate was collected by centrifugation, washed three times alternately with ethanol and water, and then dried overnight. The resulting crystals were carefully ground for at least 5 min to obtain an ethyl-modified Cu unit-site coordination polymer catalyst (denoted as Cu-eim). Cu-eim belongs to the triclinic crystal system with cell parameters a = 19.568 Å, b = 11.4672 Å, c = 13.5953 Å. , , .

[0031] The scanning electron microscope images of the above Cu single-site coordination polymer catalysts are shown below. Figure 5 X-ray diffraction pattern seen Figure 6 X-ray absorption near-edge structure spectrum is shown in Figure 7 Extended X-ray absorption fine structure spectrum (see) Figure 8 .

[0032] Reference Figure 5 It can be seen that the Cu unit-site coordination polymer catalyst described in this comparative example has a micron-sized porous solid particle morphology.

[0033] Reference Figure 6 It can be seen that the X-ray diffraction pattern of the Cu unit-site coordination polymer catalyst synthesized in this comparative experiment is in good agreement with the simulation results, indicating that the Cu unit-site coordination polymer catalyst described in this comparative example is a long-chain polymer structure formed by bridging 2-ethylimidazole with Cu atoms at a unit site.

[0034] Reference Figure 7 It can be seen that the spectral shape of the Cu single-site coordination polymer catalyst described in this comparative example is close to Cu2O, indicating that most Cu atoms in the Cu single-site coordination polymer catalyst have a monovalent oxidation state.

[0035] Reference Figure 8 It can be seen that the Cu unit site coordination polymer catalyst described in this comparative example has obvious Cu-N coordination peaks and no obvious Cu-Cu coordination peaks were observed, proving that Cu atoms in the Cu unit site coordination polymer catalyst exist in the form of Cu unit sites coordinated by N.

[0036] As can be seen from the above, the catalyst obtained in this comparative example is an ethyl-modified Cu single-site coordinated long-chain polymer.

[0037] Comparative Example 2 A Cu single-site coordination polymer catalyst is prepared by the following method: 2 mmol of commercially available Cu(NO3)2·3H2O and 4 mmol of 2-isopropylimidazole were dissolved in 12 mL of ammonia water. After magnetic stirring for 30 min, the resulting solution was transferred to a 25 mL Teflon-lined stainless steel autoclave and hydrothermally reacted at 160 °C for 80 h. The resulting precipitate was collected by centrifugation, washed three times alternately with ethanol and water, and then dried overnight. The resulting crystals were carefully ground for at least 5 min to obtain an isopropyl-modified Cu unit-site coordination polymer catalyst (denoted as Cu-ipim). Cu-ipim belongs to the triclinic crystal system, with a = 11.556 Å, b = 13.451 Å, and c = 16.430 Å. , , .

[0038] The scanning electron microscope images of the above Cu single-site coordination polymer catalysts are shown below. Figure 9 X-ray diffraction pattern seen Figure 10 X-ray absorption near-edge structure spectrum is shown in Figure 11 Extended X-ray absorption fine structure spectrum (see) Figure 12 .

[0039] Reference Figure 9 It can be seen that the Cu unit-site coordination polymer catalyst described in this comparative example has a micron-sized porous solid particle morphology.

[0040] Reference Figure 10 It can be seen that the X-ray diffraction pattern of the Cu unit site coordination polymer catalyst synthesized in this comparative experiment is in good agreement with the theoretical simulation results, indicating that the Cu unit site coordination polymer catalyst described in this embodiment is a Cu unit site long chain coordination polymer structure formed by Cu atoms bridging 2-isopropylimidazolium.

[0041] Reference Figure 11 It can be seen that the spectral shape of the Cu single-site coordination polymer catalyst described in this comparative example is close to Cu2O, indicating that most Cu atoms in the Cu single-site coordination polymer catalyst have a monovalent oxidation state.

[0042] Reference Figure 12 It can be seen that the Cu unit site coordination polymer catalyst described in this comparative example has obvious Cu-N coordination peaks and no obvious Cu-Cu coordination peaks were observed, proving that Cu atoms in the Cu unit site coordination polymer catalyst exist in the form of Cu unit sites coordinated by N.

[0043] As can be seen from the above, the catalyst obtained in this comparative example is an isopropyl-modified Cu single-site coordinated long-chain polymer.

[0044] Application Example 1 The Cu-unit-coordinated long-chain polymer catalysts described in the examples and comparative examples were used for carbon monoxide electroreduction performance testing: 24 mg of the Cu unit-site coordination polymer catalyst described in the examples or comparative examples and 84 μL of 5 wt% perfluorinated resin solution were dispersed in 10 mL of anhydrous ethanol and sonicated for 30 min to obtain a uniformly dispersed slurry. The obtained slurry was sprayed onto a gas diffusion electrode with a size of 4 cm × 6 cm using an air spray gun, and after drying, a loading of 1 mg·cm⁻¹ was obtained. -3 The Cu unit site coordination polymer catalyst composite electrode; the above composite electrode with a size of 2 cm × 2 cm is used as the working electrode, and the remaining composite electrodes are reserved for backup.

[0045] Using the composite electrode prepared in the examples and comparative examples as the working electrode, silver / silver chloride as the reference electrode, and platinum sheet as the counter electrode, the electrochemical performance was tested in a flow cell. The anode and cathode chambers of the flow cell were separated by a Nafion 117 proton exchange membrane. Before the test, carbon monoxide was introduced into the gas chamber for 30 min to remove residual gas in the pipeline. 10 mL of 1 mol / L potassium hydroxide solution was used as the circulating electrolyte in the anode and cathode chambers. During the test, the carbon monoxide gas flow rate was set to 20 mL / min, and the potassium hydroxide solution flow rate was set to 5 mL / min.

[0046] The test was conducted in constant current mode; the total current density was set to -300 mA·cm. -2 During the test, a continuous flow rate of 20 mL / min needs to be introduced into the gas chamber. -1 Carbon monoxide; during the test, oxygen generated at the anode is released into the air; the gaseous products generated at the cathode are detected by online gas chromatography, and acetic acid is detected by nuclear magnetic resonance.

[0047] With other conditions remaining unchanged, the total current density was set sequentially to -400, -500, -600, and -700 mA·cm. -2 Tests were conducted, and the acetic acid Faraday efficiency of the Cu unit-site coordination polymer catalyst at different current densities is shown in the figure. Figure 14 .

[0048] Reference Figure 13 It can be seen that at -500 mA·cm -2 At the given current density, the acetic acid faradaic efficiency of the methyl-modified Cu single-site coordination polymer catalyst in the examples is as high as 49%, which is significantly higher than that of the acetic acid faradaic efficiency of the ethyl and isopropyl-modified Cu single-site coordination long-chain polymer catalysts in the comparative examples. The acetic acid faradaic efficiency of the ethyl-modified Cu single-site coordination polymer catalyst in comparative example 1 is relatively higher than that of the isopropyl-modified Cu single-site coordination polymer catalyst in comparative example 2.

[0049] The acetic acid bias current density of the Cu unit-site coordinated long-chain polymer catalyst at different current densities is shown in the figure. Figure 14 . Reference Figure 14 It can be seen that the acetic acid bias current density of the Cu-coordinated polymer catalyst reaches a maximum of -293 mA·cm. -2 .

[0050] Reference Figure 15 It can be seen that, in terms of acetic acid partial current density and acetic acid Faradaic efficiency, Cu-mim's catalytic performance surpasses all Cu single-site catalysts reported in recent years, especially under similar current density conditions; among them, Cu CP, Cu AEs, and NGQD-Cu... 3.8, Cu-FAC, Cu1@n-C3N4-27%, Cu-NC, dual Cu SAC, Cu-MFU-41-F, Cu4BHT, Cu 1.5 / GDY refers to the DOI of the publicly available literature: 10.1002 / adma.202209567; 10.1021 / jacs.4c13197; 10.1016 / j.mtchem.2023.101398; 10.31635 / ccschem.022.202201910; 10.1126 / sciadv.ade3557; 10.1016 / j.mtphys.2021.100418; 10.1021 / acsmaterialslett.1c00543; 10.1002 / smll.202509324; 10.1016 / j.apcatb.2024.123887; Found at 10.1002 / anie.202011836.

[0051] In fact, compared to other Cu-based catalysts, such as those disclosed in patent CN113549948A, the Cu single-site coordination polymer of this invention exhibits a higher acetic acid bias current density, indicating higher catalytic activity. Compared to patent CN113881955A, the Cu single-site coordination polymer of this invention has stronger structural tunability, making it a superior catalyst platform for mechanism research; furthermore, the catalyst synthesis steps of patent CN113881955A are cumbersome and complex, while the synthesis of the Cu single-site coordination polymer catalyst of this invention is simpler and more direct. Compared to patent CN115433957A, the Cu single-site coordination polymer of this invention exhibits a higher total current density, indicating higher catalytic activity and avoiding the generation of byproducts such as CO and formic acid; furthermore, patent CN115433957A uses CO2 as a reactant.

[0052] Figure 16-18 Electrochemical in-situ extended X-ray absorption fine structure spectra of the Cu unit-site coordination polymer catalysts described in the examples and comparative examples are shown below. Figure 16-18It can be seen that in the electrochemical in-situ extended X-ray absorption fine structure spectroscopy test, Cu-mim exhibited obvious Cu-N coordination peaks at all test potentials, and no obvious Cu-Cu signal was observed, indicating that the Cu-N structure in Cu-mim has good coordination stability under electrolysis conditions. Figure 16 In contrast, in the in-situ extended X-ray absorption fine structure spectrum of Cu-eim, as the potential increases from OCP to -1.3 V vs RHE, the Cu-N peak intensity significantly weakens while the Cu-Cu peak intensity gradually increases, indicating that under electrolytic conditions, the Cu unit point structure in Cu-eim gradually disintegrates while Cu particles precipitate and grow. Figure 17 In the in-situ extended X-ray absorption fine structure spectrum of Cu-ipim, only the formation of Cu-Cu bonds was observed, while the Cu-N peak almost completely disappeared, indicating that the Cu unit point structure in Cu-ipim completely disintegrated under electrolysis conditions, and only precipitated Cu particles remained on the electrode surface. Figure 18 ).

[0053] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A Cu single-site coordination polymer catalyst characterized in that, It is to use 2-methyl imidazole as ligand, and use hydrothermal method to carry out coordination polymerization reaction with divalent copper salt.

2. The Cu unit point coordination polymer catalyst according to claim 1, characterized in that, It belongs to the triclinic system with cell parameters a = 17.061 A, b = 11.299 A, c = 8.3845 A, , , . 3.The Cu unit point coordination polymer catalyst according to claim 1 or 2, characterized in that, The divalent copper salt is at least one of Cu(NO3)2·3H2O, CuCl2·2H2O, CuSO4 or Cu2(OH)2CO3. 4.The Cu unit point coordination polymer catalyst according to claim 1 or 2, characterized in that, The molar ratio of 2-methyl imidazole to divalent copper salt is 1-2:

1.

5. A process for the preparation of the Cu site-coordinated polymer catalyst according to any one of claims 1 to 4, characterized in that, It comprises: 2-methyl imidazole and divalent copper salt are dissolved in ammonia water, and the obtained solution is placed in a hydrothermal reactor for hydrothermal reaction, thereby obtaining the Cu unit point coordination polymer catalyst.

6. The method for preparing Cu unit point coordination polymer catalyst according to claim 5, characterized in that, The temperature of the hydrothermal reaction is 150-170 DEG C, and the time is 70-90 h.

7. The method for preparing the Cu unit point coordination polymer catalyst according to claim 5 or 6, characterized in that, It also comprises: The product obtained by hydrothermal reaction is centrifuged, washed, dried and ground.

8. The use of the Cu unit point coordination polymer catalyst of any one of claims 1-4 in the preparation of acetic acid by carbon monoxide electro-reduction.

9. Use of the Cu unit point coordination polymer catalyst according to claim 8 for the electroreduction of carbon monoxide to acetic acid, characterized in that, It comprises: In a flow electrolysis cell, the Cu unit point coordination polymer catalyst is used as a working electrode, silver / silver chloride is used as a reference electrode, and a platinum sheet is used as a counter electrode, carbon monoxide is passed into the working electrode, a negative current is applied for electro-reduction reaction, and acetic acid is obtained.

10. Use of the Cu unit point coordination polymer catalyst according to claim 9 for the electroreduction of carbon monoxide to acetic acid, characterized in that, The flow rate of carbon monoxide is 1-50 mL·min -1 The electrolyte is at least one of potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium bicarbonate or potassium bicarbonate solution, and the electrolyte concentration is 0.1-10 mol·L -1 The negative current is -100- -1000 mA·cm -2 .

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