Pulsed current enhanced MOF-based catalysts, methods of making and using the same

Abstract

The application discloses a kind of pulse current enhanced MOF-based catalyst and its preparation method and application, belong to the catalytic material field of atmospheric pollutant control.The copper salt is dissolved in the mixed solution of DMF and ethanol with polyvinylpyrrolidone, and then formic acid is added;Cu-TCPP is dissolved in the mixed solution of DMF and ethanol;The above-mentioned solution is mixed and dispersed uniformly, and then heated and dried to obtain PML-Cu;PML-Cu is taken in inert gas calcination to obtain PML-CuNPs;Pulse-PML-CuNPs is obtained by treating PML-CuNPs with pulse current.This method generates active centers in-situ in two-dimensional MOF-based material Cu-TCPP by node metal in-situ reduction method, and the synthesized two-dimensional MOF-based electrocatalyst PML-CuNPs has monatomic layer structure, which can maximize mass transfer rate;The application also changes the surface state of active center by pulse current method, changes the surface roughness and valence state of Cu nanoparticles, and enhances the reaction efficiency of CO2 electroreduction to multi-carbon products.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalytic materials for controlling atmospheric pollutants, and in particular relates to a pulse current enhanced MOF-based catalyst and a preparation method and application thereof. Background Art

[0002] CO2 storage and efficient conversion and utilization technologies are particularly important. They are not only key means to mitigate climate change, but also an important direction for promoting the development of new energy industries.

[0003] As a stable and readily available energy source, electricity offers enormous potential for the catalytic conversion of CO2. This not only transforms this greenhouse gas into valuable chemicals or fuels, but also enables zero-emission storage and conversion, significantly contributing to the development of a low-carbon, circular economy. However, the current development of CO2 electroreduction technology faces numerous bottlenecks, the most prominent of which is the limited product distribution.

[0004] At present, the products of CO2 electroreduction are mainly concentrated in single-carbon products with low added value, such as CO and methane. In order to achieve high-value utilization of CO2 resources, scientists are committed to exploring catalytic systems that can promote CC bond coupling, in order to obtain di-carbon or even multi-carbon products with higher value.

[0005] Copper-based catalysts are considered an effective way to convert CO2 to multi-carbon products, but their practical application still faces severe challenges. First, Cu-based catalysts have poor product selectivity, meaning that multiple products are often generated simultaneously under the same reaction conditions, making it difficult to efficiently and specifically synthesize the target product. Second, the activity of Cu-based catalysts needs to be improved to meet the efficiency and output requirements of industrial production. Therefore, how to design and optimize Cu-based catalysts to improve their selectivity and catalytic activity for specific multi-carbon products has become a key scientific issue that needs to be addressed in the field of CO2 electroreduction. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a pulse current enhanced MOF-based catalyst and its preparation method and application, which solves the problems of poor product selectivity and low activity faced by Cu-based catalysts when performing CO2 electroreduction to multi-carbon products.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing a pulse current enhanced MOF-based catalyst, comprising:

[0009] Dissolve copper salt and polyvinyl pyrrolidone in a mixed solution of N,N-dimethylformamide and ethanol, and then add formic acid to obtain solution A;

[0010] Dissolve Cu-TCPP in a mixed solution of DMF and ethanol to obtain solution B;

[0011] Disperse solution A and solution B evenly, heat and dry to obtain PML-Cu;

[0012] PML-Cu was calcined under inert atmosphere to obtain PML-CuNPs;

[0013] Under inert atmosphere, PML-CuNPs were treated with pulse current to obtain Pulse-PML-CuNPs.

[0014] The mass ratio of the copper salt, polyvinyl pyrrolidone and Cu-TCPP is (20-25):100:(45-50).

[0015] The copper salt is Cu(NO3)2·3H2O or CuCl2·2H2O.

[0016] The A solution and the B solution are evenly dispersed, and heated and dried to obtain PML-Cu, specifically:

[0017] Solution A and solution B are mixed and dispersed evenly, and heated in an oven at 80-100°C for 8-10 hours.

[0018] The PML-Cu is calcined in an inert gas to obtain PML-CuNPs, specifically:

[0019] PML-Cu was calcined at 250-280 °C for 2-3 h in an inert atmosphere to obtain PML-CuNPs.

[0020] Pulse-PML-CuNPs were obtained by treating PML-CuNPs with pulse current, specifically:

[0021] PML-CuNPs are dispersed in a volatile solvent and then coated on a working electrode. Under inert atmosphere, a three-electrode system is used to treat the PML-CuNPs with a pulse current in an electrolyte to obtain Pulse-PML-CuNPs.

[0022] The PML-CuNPs are treated with a pulse current to obtain Pulse-PML-CuNPs, specifically:

[0023] Pulse-PML-CuNPs were obtained by pulse-treating PML-CuNPs with a pulse current of -0.5 V and +1 V starting from a negative potential and pulsed every 1 s for 30 s.

[0024] The electrolyte is a 0.1-0.2 mol / L KHCO3 solution.

[0025] The present invention also provides a pulse current enhanced MOF-based catalyst prepared by the above preparation method.

[0026] The present invention also provides the application of the pulse current enhanced MOF-based catalyst in the field of CO2 electroreduction.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention provides a method for preparing a pulsed current-enhanced MOF-based catalyst. This method generates active centers in situ within the two-dimensional MOF-based material Cu-TCPP through in-situ reduction of the node metal, eliminating the need for external active sites and facilitating easy operation. The synthesized two-dimensional MOF-based electrocatalyst, PML-CuNPs, possesses a single-atomic layer structure, maximizing mass transfer rates and significantly improving reaction rates. The present invention also utilizes pulsed current to modify the surface state of the active centers, altering the surface roughness and valence of the Cu nanoparticles, thereby enhancing the selectivity of the CO2 electroreduction reaction to multi-carbon products and achieving high product selectivity for ethylene.

[0029] The pulse current enhanced MOF-based catalyst provided by the present invention is subjected to pulse current treatment. Under oxidation potential conditions, the surface of CuNPs will be partially oxidized, and partially reduced under reduction potential conditions. After multiple pulses, the CuNPs will show an uneven distribution of oxidized and reduced Cu, which increases the surface roughness of the catalyst and increases the distribution ratio of oxidized Cu. Studies have shown that oxidized Cu is more conducive to the production of multi-carbon products.

[0030] The catalyst prepared by the present invention is used for the catalytic reaction of CO2 electroreduction to multi-carbon products. At the optimal potential, the Faradaic efficiency of ethylene reaches 28.8%, and the Faradaic efficiency of carbon-containing products reaches more than 50%. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments:

[0032] Figure 1 Schematic diagram of the electrocatalytic reduction of CO2 to C2H4 using the catalyst prepared in the present invention;

[0033] Figure 2 is the voltage curve during the pulse treatment process of the present invention;

[0034] Figure 3 The distribution diagram of the electrocatalytic CO2 reduction products of PML-CuNPs prepared in Example 1 in 0.1 mol / L KHCO3 electrolyte;

[0035] Figure 4 This is the distribution diagram of the electrocatalytic CO2 reduction products of Pulse-PML-CuNPs prepared in Example 2 in 0.1 mol / L KHCO3 electrolyte;

[0036] Figure 5 This is the distribution diagram of the electrocatalytic CO2 reduction products of Pulse-PML-CuNPs prepared in Example 3 under 0.5 mol / L KHCO3 electrolyte conditions. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0038] Metal-organic frameworks (MOFs) are an emerging class of crystalline porous materials whose metal nodes and bridging ligands offer excellent designability and tailorability. By rationally combining and functionalizing their components, MOF-based materials can be applied in diverse scenarios. Consequently, MOF-based materials have garnered widespread attention across numerous fields.

[0039] The present invention is based on a two-dimensional MOF with Cu as the metal node. By annealing in a low-temperature N2 atmosphere, the Cu at a portion of the nodes is reduced to Cu nanoparticles. The Cu nanoparticles are then further treated with a pulse current to change the surface roughness and valence state of the Cu nanoparticles, thereby achieving the coexistence of oxidized and reduced copper on the surface of the Cu nanoparticles, thereby enhancing the catalytic performance of the CO2 electroreduction to multi-carbon products.

[0040] The present invention will be further described below with reference to the accompanying drawings:

[0041] A method for preparing a pulse current-enhanced MOF-based catalyst comprises the following steps:

[0042] Dissolve copper salt and polyvinyl pyrrolidone in a mixed solution of N,N-dimethylformamide (DMF) and ethanol, and then add formic acid to obtain solution A;

[0043] Dissolve Cu-TCPP in a mixed solution of DMF and ethanol to obtain solution B;

[0044] Solution A and solution B were evenly dispersed, heated and dried to obtain a purple-red powder, which was named PML-Cu;

[0045] Under inert atmosphere, PML-Cu was calcined to obtain red powder, which was named PML-CuNPs;

[0046] Under inert atmosphere, PML-CuNPs were treated with pulse current to obtain powder, which was named Pulse-PML-CuNPs.

[0047] The present invention is further explained below:

[0048] In some embodiments, the ratio of copper salt, polyvinyl pyrrolidone, and Cu-TCPP is (20-25):100:(45-50). It should be noted that an appropriate amount of copper salt ensures sufficient copper ions to bind to the TCPP ligand to form a stable and functional Cu-TCPP complex; and the amount of polyvinyl pyrrolidone is sufficient to effectively disperse and stabilize the other components without excessively negatively impacting the system.

[0049] In some embodiments, the copper salt is Cu(NO3)2·3H2O or CuCl2·2H2O. It should be noted that these two copper salts have good solubility and provide the copper ions required for the reaction.

[0050] In some embodiments, the mixing ratio of N,N-dimethylformamide and ethanol is (2-3):1.

[0051] In some embodiments, the solution A and the solution B are evenly dispersed, heated and dried to obtain a purple-red powder, which is denoted as PML-Cu. Specifically:

[0052] Solution A and Solution B were placed in a polytetrafluoroethylene-lined reactor and mixed evenly. The mixture was then heated in an oven at 80-100°C for 8-10 hours. It should be noted that the reaction rate and product yield can be controlled by adjusting the appropriate temperature and heating time, thereby adjusting the structure and properties of PML-Cu.

[0053] In some embodiments, the PML-Cu is calcined in an inert gas to obtain a red powder, specifically:

[0054] Under the condition of inert atmosphere, PML-Cu is placed in a heat-resistant container (magnetic boat, crucible, etc.) and put into a tube furnace, calcined at 250-280℃ for 2-3 hours to obtain a red powder, which is recorded as PML-CuNPs. It should be noted that PML-Cu is reduced to Cu nanoparticles by calcination at this temperature and time, and the uniform distribution of Cu nanoparticles in the PML matrix results in PML-CuNPs with a monolayer structure, which can maximize the mass transfer rate.

[0055] In some embodiments, PML-CuNPs is treated by pulse current under the condition of inert atmosphere to obtain the product recorded as Pulse-PML-CuNPs, which is specifically:

[0056] PML-CuNPs is dispersed with a volatile solvent (ethanol, methanol, acetone, etc.) and coated on carbon paper or carbon cloth as a working electrode. A three-electrode system (Ag / AgCl electrode as a reference electrode, Pt electrode as a counter electrode, and working electrode) is used to treat PML-CuNPs by pulse current in an electrolyte under inert atmosphere to obtain Pulse-PML-CuNPs.

[0057] The minimum potential of the pulse current is -0.5V and the maximum potential is +1.0V. The pulse is applied every 1s starting from the negative potential, and the pulse treatment of PML-CuNPs is performed for 30s to obtain Pulse-PML-CuNPs. It should be noted that the surface of CuNPs is partially oxidized under the condition of oxidation potential, and some reduction occurs under the condition of reduction potential. After multiple pulses, CuNPs will present uneven distribution of oxidized and reduced Cu, which increases the surface roughness of the catalyst and increases the proportion of oxidized Cu. Oxidized Cu is more conducive to the production of multi-carbon products.

[0058] The electrolyte is a 0.1-0.2mol / L KHCO3 solution.

[0059] Electrocatalytic CO2 reduction reaction:

[0060] A three-electrode system is used to coat the prepared catalyst on carbon paper as a working electrode in a KHCO3 solution under the condition of CO2 atmosphere, and CO2 is reduced to multi-carbon products, and performance tests are carried out.

[0061] In order to better illustrate the purpose, technical scheme and advantages of the present application, the present application will be further described below with reference to specific examples.

[0062] In the following examples, unless otherwise specified, each material used can be obtained through ordinary channels; the test method used is a conventional method in the art.

[0063] Example 1

[0064] PML-Cu: Dissolve 2.4 mg of Cu(NO₃)₂·3H₂O and 10 mg of polyvinylpyrrolidone in a mixture of 9 ml of N,N-dimethylformamide (DMF) and 3 ml of ethanol. Add 40 μl of formic acid, referred to as Solution A. Dissolve 4.7 mg of Cu-TCPP in a mixture of 3 ml of DMF and 1 ml of ethanol, referred to as Solution B. Solution A and B were mixed in a Teflon-lined reactor and placed in an 80°C oven for 8 hours. After cooling, the mixture was washed with ethanol and dried to yield a purple-red powder, designated PML-Cu.

[0065] PML-CuNPs: 20 mg of PML-Cu was weighed into a magnetic boat, placed in a tube furnace, and calcined at 250°C for two hours under a nitrogen atmosphere to obtain a red powder, which was recorded as PML-CuNPs.

[0066] The electrocatalytic CO2 reduction reaction using the catalyst prepared in this example was carried out in a 0.1 mol / L KHCO3 electrolyte.

[0067] Example 2

[0068] PML-Cu: Dissolve 4.8 mg of Cu(NO₃)₂·3H₂O and 20 mg of polyvinylpyrrolidone in a mixture of 18 ml of N,N-dimethylformamide (DMF) and 6 ml of ethanol. Add 80 μl of formic acid, referred to as Solution A. Dissolve 9.4 mg of Cu-TCPP in a mixture of 6 ml of DMF and 2 ml of ethanol, referred to as Solution B. Solution A and B were mixed in a Teflon-lined reactor and placed in an 80°C oven for 8 hours. After cooling, the mixture was washed with ethanol and dried to yield a purple-red powder, designated PML-Cu.

[0069] PML-CuNPs: 20 mg of PML-Cu was weighed into a magnetic boat, placed in a tube furnace, and calcined at 260°C for 2 h under a nitrogen atmosphere to obtain a red powder, which was recorded as PML-CuNPs.

[0070] Pulse-PML-CuNPs: PML-CuNPs were dispersed in ethanol and coated on carbon paper. A three-electrode system (Ag / AgCl electrode as reference electrode, Pt electrode as counter electrode, catalyst coated on carbon paper as working electrode) was used to treat PML-CuNPs in a 0.1 mol / L KHCO3 solution under N2 atmosphere with a pulse current of -0.5 V and +1 V. The voltage changes with time as shown in Figure 2. Figure 2 shown.

[0071] The electrocatalytic CO2 reduction reaction using the catalyst prepared in this example was carried out in a 0.1 mol / L KHCO3 electrolyte.

[0072] Example 3

[0073] PML-Cu: Dissolve 2.4 mg of Cu(NO₃)₂·3H₂O and 10 mg of polyvinylpyrrolidone in a mixture of 9 ml of N,N-dimethylformamide (DMF) and 3 ml of ethanol. Add 40 μl of formic acid, referred to as Solution A. Dissolve 4.7 mg of Cu-TCPP in a mixture of 3 ml of DMF and 1 ml of ethanol, referred to as Solution B. Solution A and B were mixed in a polytetrafluoroethylene-lined reactor and placed in an 80°C oven for 10 hours. After cooling, wash with ethanol, and dry to obtain a purple-red powder, designated PML-Cu.

[0074] PML-CuNPs: 20 mg of PML-Cu was weighed into a magnetic boat, placed in a tube furnace, and calcined at 280°C for two hours under a nitrogen atmosphere to obtain a red powder, which was recorded as PML-CuNPs.

[0075] Pulse-PML-CuNPs: PML-CuNPs were dispersed in ethanol and coated on carbon paper. A three-electrode system (Ag / AgCl electrode as reference electrode, Pt electrode as counter electrode, catalyst coated on carbon paper as working electrode) was used to treat PML-CuNPs in a 0.2 mol / L KHCO3 solution under N2 atmosphere with a pulse current of -0.5 V and +1 V. The voltage changes with time as shown in Figure 2. Figure 2 shown.

[0076] The electrocatalytic CO2 reduction reaction performed by the catalyst prepared in this example was carried out in a 0.5 mol / L KHCO3 electrolyte.

[0077] like Figure 3 and Figure 4As shown, the catalytic results show that the electroreduction product of the pulse-PML-CuNPs catalyst after pulse treatment is mainly ethylene. At the optimal potential, the Faradaic efficiency of ethylene reaches 28.8%, and the Faradaic efficiency of carbon-containing products reaches over 50%. In contrast, the electroreduction products of the PML-CuNPs catalyst without pulse treatment are mainly single-carbon products such as CO and methane, and the Faradaic efficiency of ethylene is only 12.9%. There are significant differences in the types of reduction products and Faradaic efficiencies between the two, which are closely related to the surface roughness and valence state of the active center Cu. After pulse treatment, the CuNPs surface will be partially oxidized under oxidizing potential conditions and partially reduced under reducing potential conditions. After multiple pulses, the CuNPs will show an uneven distribution of oxidized and reduced Cu, which increases the catalyst surface roughness and the distribution ratio of oxidized Cu. Studies have shown that oxidized Cu is more conducive to the production of multi-carbon products.

[0078] like Figure 5 As shown in Figure 2, the Faradaic efficiency of ethylene reduction in a 0.5 mol / L KHCO3 electrolyte is only 22.1% at the optimal potential. 0.5 mol / L KHCO3 has a weaker buffering capacity than 0.1 mol / L KHCO3, resulting in a higher pH at the electrode surface, which is not conducive to the production of multi-carbon products.

[0079] Example 4

[0080] PML-Cu: Dissolve 4 mg of Cu(NO₃)₂·3H₂O and 20 mg of polyvinylpyrrolidone in a mixture of 18 ml of N,N-dimethylformamide (DMF) and 6 ml of ethanol. Add 80 μl of formic acid, referred to as Solution A. Dissolve 10 mg of Cu-TCPP in a mixture of 6 ml of DMF and 2 ml of ethanol, referred to as Solution B. Solution A and B were mixed in a polytetrafluoroethylene-lined reactor and placed in an oven at 100°C for 10 hours. After cooling, the mixture was washed with ethanol and dried to yield a purple-red powder, designated PML-Cu.

[0081] PML-CuNPs: 20 mg of PML-Cu was weighed into a magnetic boat, placed in a tube furnace, and calcined at 280°C for 3 h under a nitrogen atmosphere to obtain a red powder, which was recorded as PML-CuNPs.

[0082] Pulse-PML-CuNPs: PML-CuNPs were dispersed with ethanol and coated on carbon paper, using a three-electrode system (Ag / AgCl electrode as reference electrode, Pt electrode as counter electrode, and catalyst coated on carbon paper as working electrode), in 0.2 mol / L KHCO3 solution, under N2 atmosphere, PML-CuNPs were treated with pulse current with lower limit -0.5 V and upper limit +1 V, and Pulse-PML-CuNPs were obtained after treatment. The voltage change with time is shown in FIG. 1. Figure 2

[0083] Example 5

[0084] PML-Cu: 5 mg Cu(NO3)2·3H2O and 20 mg polyvinylpyrrolidone were dissolved in a mixed solution of 18 ml N,N-dimethylformamide (DMF) and 6 ml ethanol, and 80 ul formic acid was added, which was referred to as A liquid. 9 mg Cu-TCPP was weighed and dissolved in a mixed solution of 6 ml DMF and 2 ml ethanol, which was referred to as B liquid. A and B were mixed in a reaction kettle with a polytetrafluoroethylene liner, placed in a 90°C oven for 10 hours, washed with ethanol after cooling, dried, and a purple red powder was obtained, which was referred to as PML-Cu.

[0085] PML-CuNPs: 20 mg PML-Cu was weighed in a magnetic boat and placed in a tube furnace, calcined at 260°C for 3 hours under nitrogen atmosphere, and a red powder was obtained, which was referred to as PML-CuNPs;

[0086] Pulse-PML-CuNPs: PML-CuNPs were dispersed with ethanol and coated on carbon paper, using a three-electrode system (Ag / AgCl electrode as reference electrode, Pt electrode as counter electrode, and catalyst coated on carbon paper as working electrode), in 0.2 mol / L KHCO3 solution, under N2 atmosphere, PML-CuNPs were treated with pulse current with lower limit -0.5 V and upper limit +1 V, and Pulse-PML-CuNPs were obtained after treatment. The voltage change with time is shown in FIG. 1. Figure 2

[0087] Example 6

[0088] ​​PML-Cu: 4.8 mg Cu(NO3)2.3H2O and 20 mg polyvinylpyrrolidone were dissolved in a mixed solution of 18 ml N,N-dimethylformamide (DMF) and 6 ml ethanol, and 80 ul formic acid was added to form solution A. 9.2 mg Cu-TCPP was dissolved in a mixed solution of 6 ml DMF and 2 ml ethanol to form solution B. Solutions A and B were mixed in a reaction kettle lined with polytetrafluoroethylene, and placed in a 100 °C oven for 9 hours. After cooling, ethanol was used for washing and drying to obtain a purple red powder, which was recorded as PML-Cu.

[0089] PML-CuNPs: 20 mg PML-Cu was weighed in a magnetic boat and placed in a tube furnace, and calcined at 270 °C for 2 hours under a nitrogen atmosphere to obtain a red powder, which was recorded as PML-CuNPs.

[0090] Pulse-PML-CuNPs: PML-CuNPs was dispersed with ethanol and coated on carbon paper. A three-electrode system was used (Ag / AgCl electrode as reference electrode, Pt electrode as counter electrode, and catalyst coated on carbon paper as working electrode). PML-CuNPs was treated with a pulse current with lower limit -0.5 V and upper limit +1 V in 0.1 mol / L KHCO3 solution under N2 atmosphere. After treatment, Pulse-PML-CuNPs was obtained. The voltage change with time is shown in Figure 2 .

[0091] Example 7

[0092] PML-Cu: 4.8 mg Cu(NO3)2.3H2O and 20 mg polyvinylpyrrolidone were dissolved in a mixed solution of 18 ml N,N-dimethylformamide (DMF) and 6 ml ethanol, and 80 ul formic acid was added to form solution A. 9.2 mg Cu-TCPP was dissolved in a mixed solution of 6 ml DMF and 2 ml ethanol to form solution B. Solutions A and B were mixed in a reaction kettle lined with polytetrafluoroethylene, and placed in a 100 °C oven for 9 hours. After cooling, ethanol was used for washing and drying to obtain a purple red powder, which was recorded as PML-Cu.

[0093] PML-CuNPs: 20 mg PML-Cu was weighed in a magnetic boat and placed in a tube furnace, and calcined at 270 °C for 2 hours under a nitrogen atmosphere to obtain a red powder, which was recorded as PML-CuNPs.

[0094] Pulse-PML-CuNPs: PML-CuNPs were dispersed in ethanol and coated on carbon paper. A three-electrode system (Ag / AgCl electrode as reference electrode, Pt electrode as counter electrode, catalyst coated on carbon paper as working electrode) was used to treat PML-CuNPs in a 0.1 mol / L KHCO3 solution under N2 atmosphere with a pulse current of -0.5 V and +1 V. The voltage changes with time as shown in Figure 2. Figure 2 shown.

[0095] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and a separate point value, and the separate point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be considered as specifically disclosed in this article.

[0096] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art may still modify or make equivalent substitutions to the specific implementations of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the scope of protection of the claims of the present invention to be approved.

Claims

1. A method for preparing a pulse current enhanced MOF-based catalyst, characterized in that: include: Dissolve copper salt and polyvinyl pyrrolidone in a mixed solution of N,N-dimethylformamide and ethanol, and then add formic acid to obtain solution A; Dissolve Cu-TCPP in a mixed solution of DMF and ethanol to obtain solution B; Disperse solution A and solution B evenly, heat and dry to obtain PML-Cu; PML-Cu was calcined under inert atmosphere to obtain PML-CuNPs; PML-CuNPs were dispersed in a volatile solvent and then coated on a working electrode. Under inert atmosphere, a three-electrode system was used to apply a pulse current with a lower limit of -0.5V and an upper limit of +1V in an electrolyte. The PML-CuNPs were pulsed every 1s starting from a negative potential for 30s to obtain Pulse-PML-CuNPs.

2. The method for preparing a pulse current enhanced MOF-based catalyst according to claim 1, characterized in that: The mass ratio of the copper salt, polyvinyl pyrrolidone and Cu-TCPP is (20-25):100:(45-50).

3. The method for preparing a pulse current enhanced MOF-based catalyst according to claim 1, characterized in that: The copper salt is Cu(NO3)2·3H2O or CuCl2·2H2O.

4. The method for preparing a pulse current enhanced MOF-based catalyst according to claim 1, characterized in that: The A solution and the B solution are evenly dispersed, and heated and dried to obtain PML-Cu, specifically: Solution A and solution B are mixed and dispersed evenly, and heated in an oven at 80-100°C for 8-10 hours.

5. The method for preparing a pulse current enhanced MOF-based catalyst according to claim 1, characterized in that: The PML-Cu is calcined in an inert gas to obtain PML-CuNPs, specifically: In an inert gas, PML-Cu was calcined at 250-280°C for 2-3 hours to obtain PML-CuNPs.

6. The method for preparing a pulse current enhanced MOF-based catalyst according to claim 1, characterized in that: The electrolyte is a 0.1-0.2 mol / L KHCO3 solution.

7. A pulse current enhanced MOF-based catalyst prepared according to the preparation method according to any one of claims 1 to 6.

8. Application of the pulse current enhanced MOF-based catalyst according to claim 7 in the field of CO2 electroreduction.

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