An octahedral BIF-29 catalytic material and its continuous preparation method and application

Abstract

The present invention discloses an octahedral BIF-29 catalytic material and a continuous preparation method and application thereof, which belong to the field of electrochemical catalysis. The octahedral BIF-29 catalytic material includes a metal copper salt and an organic ligand, wherein the organic ligand is tri(1H-imidazolyl) potassium borohydride; the metal copper salt is copper nitrate. The octahedral BIF-29 catalytic material is an M6L8 structure, that is, six metal copper sites are connected to eight organic ligands to form a cage structure, with six exposed mononuclear copper centers, which are connected to the ligands through copper-nitrogen bonds inside, and the micromorphology presents an octahedral morphology. The octahedral BIF-29 catalytic material only needs to be continuously synthesized at a lower temperature and can be used as an efficient electrocatalytic reduction of carbon dioxide catalyst without further treatment. The octahedral BIF-29 catalytic material in the present invention has an electrocatalytic carbon dioxide reduction conversion efficiency of up to 93.7% when participating in the electrocatalytic carbon dioxide reduction reaction.

Description

Technical Field

[0001] The invention belongs to the field of electrochemical catalysis, and particularly relates to an octahedral BIF-29 catalytic material and a continuous preparation method and application thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] The overuse of fossil fuels has led to a rapid increase in atmospheric carbon dioxide concentrations, disrupting the natural balance of the carbon cycle. This has led to global warming, with attendant frequent storms, droughts, and rising sea levels. As climate change intensifies, there is an urgent need to close the carbon cycle by developing advanced technologies to protect the ecological environment. Electrocatalytic reduction of carbon dioxide to value-added chemicals using renewable electricity offers a practical solution to offset the additional carbon footprint. However, the disruption of the symmetrical linear structure brings with it a high activation energy barrier and the stability of the C=O bond (750 kJ mol -1 ), making electrochemical processes challenging. The inherently sluggish kinetics of these reactions highlight the crucial role of electrocatalysts. In this regard, researchers and governments worldwide have devoted significant attention to the field of energy conversion and storage materials over the past few decades.

[0004] Metal-organic frameworks (MOFs) are ideal materials due to their extraordinary structural versatility, synthetic tunability, ultrahigh porosity, and high surface area. MOFs are crystalline structures composed of inorganic metal ions and organic ligands that can be synthesized through a bottom-up assembly method under solvothermal conditions. To date, many MOFs have been widely used in batch applications such as heterogeneous catalysis, gas energy storage (H2 and CH4), carbon dioxide capture, separation, and reduction reactions. However, the insulating nature (lack of electrical conductivity) of most existing MOFs has limited their successful application in electrocatalysis, which is at the core of applications in energy storage and power generation. Summary of the Invention

[0005] In order to address the deficiencies of the prior art, the purpose of the present invention is to provide an octahedral BIF-29 catalytic material and its continuous preparation method and application. The octahedral BIF-29 catalytic material proposed in the present invention can be used as a high-efficiency electrocatalytic reduction catalyst for carbon dioxide without carbonization treatment. The octahedral BIF-29 catalytic material is a unique π-π stacking interaction that provides space and orbital overlap for electrons, forming a spatial electron transport path. The typical M6L8 structure has six exposed planar mononuclear copper centers, which can maximize the exposure of catalytic active sites, accelerate the approach of reactant molecules to the active sites and the desorption of products, and improve the selectivity of the target product.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] In the first aspect, the present invention provides an octahedral BIF-29 catalytic material, comprising a metal copper salt and an organic ligand. The octahedral BIF-29 catalytic material has an M6L8 structure, i.e., six metal copper sites are connected to eight organic ligands to form a cage-like structure, having six exposed mononuclear copper centers, which are internally connected to the ligands through copper-nitrogen bonds, and the microscopic morphology presents an octahedral morphology.

[0008] Furthermore, the diameter of the octahedral BIF-29 catalytic material is 2-5 μm.

[0009] Furthermore, the organic ligand is potassium tris(1H-imidazolyl)borohydride; and the metal copper salt is copper nitrate.

[0010] In a second aspect, the present invention provides a continuous preparation method of the above-mentioned octahedral BIF-29 catalytic material, comprising the following steps:

[0011] Assembling a microfluidic pneumatic continuous reaction device, the microfluidic pneumatic continuous reaction device comprising syringe A, syringe B, syringe C, a reaction tube, a mixer, a heating device, and a collecting device, syringe A being pre-filled with an organic ligand solution, syringe B being pre-filled with a metal copper salt solution, and syringe C being pre-filled with gas;

[0012] The organic ligand solution in syringe A and the metal copper salt solution in syringe B are mixed in a mixer to obtain a reaction mixture. The reaction mixture flows continuously in the reaction tube. The gas in syringe C is used to cut the continuously flowing reaction mixture into segments of uniform size. The segments are the reaction micro-locations. The segments in the reaction tube flow through a heating device with a set temperature, and the products are collected by a collecting device.

[0013] Furthermore, in the microfluidic pneumatic continuous reaction device, syringe A and syringe B are respectively connected to the mixer, the mixer and the collection device are connected through a reaction tube, a heating device is provided between the mixer and the collection device, and the reaction tube passes through the heating device; syringe C is connected to the reaction tube, and the connection between syringe C and the reaction tube is located between the mixer and the heating device.

[0014] Furthermore, the microfluidic pneumatic continuous reaction device further comprises a tee, and the C syringe is connected to the reaction tube via the tee;

[0015] Furthermore, the reaction tube is a transparent polytetrafluoroethylene hose;

[0016] Furthermore, the inner diameter of the reaction tube is 1-3 mm, the outer diameter is 2-4 mm, and the difference between the outer diameter and the inner diameter is greater than 0.5 mm.

[0017] Furthermore, the metal copper salt is copper nitrate; and the organic ligand is potassium tris(1H-imidazolyl)borohydride.

[0018] Furthermore, the molar ratio of the copper element in the metal copper salt to the organic ligand is (0.5-3):1.

[0019] Furthermore, the required gas is selected from any one of argon, nitrogen or air.

[0020] Furthermore, the reaction temperature of the heating device is 60-80°C.

[0021] Furthermore, the organic ligand solution is an organic ligand dissolved in an organic solvent a; preferably, the organic solvent a is at least one of N,N-dimethylformamide and N,N-dimethylacetamide.

[0022] Furthermore, the metal salt solution is a metal copper salt dissolved in an organic solvent b; preferably, the organic solvent b is at least one of acetone, methanol, and ethanol.

[0023] Furthermore, the concentration of the metal copper salt solution is 0.1-8 mol / L, and the concentration of the organic ligand solution is 0.05-0.5 mol / L.

[0024] Furthermore, the flow rate of the fluid in syringe A is 50-200 μL / min, the flow rate of the fluid in syringe B is 50-200 μL / min, and the flow rate of the fluid in syringe C is 400-1000 μL / min.

[0025] Furthermore, the ratio of the fluid flow rates in syringe A, syringe B, and syringe C is 1:1:(5-20).

[0026] In a third aspect, the present invention provides a working electrode for electrocatalytic reduction of CO2, the working electrode comprising a substrate and a catalyst supported on the substrate; the catalyst is selected from the above-mentioned octahedral BIF-29 catalytic material or the octahedral BIF-29 catalytic material prepared by the above-mentioned continuous preparation method.

[0027] Furthermore, the catalyst loading on the working electrode is 0.1-2 mg / cm 2 ; The substrate is selected from at least one of carbon paper, carbon cloth, and carbon felt.

[0028] In a fourth aspect, the present invention provides a use of the above-mentioned octahedral BIF-29 catalytic material or the octahedral BIF-29 catalytic material prepared by the above-mentioned continuous preparation method or the above-mentioned working electrode in the electrocatalytic reduction of CO2.

[0029] In a fifth aspect, the present invention provides a method for electrocatalytic reduction of CO2, wherein the above-mentioned octahedral BIF-29 catalytic material is mixed with an organic solvent to obtain a dispersion, which is sprayed on a substrate, dried, placed in an electrolytic cell, and carbon dioxide is introduced for electrocatalytic reaction.

[0030] The beneficial effects of the present invention are:

[0031] 1. The present invention provides an octahedral BIF-29 catalytic material with an overall octahedral morphology and a diameter of 2-5 μm. The octahedral BIF-29 catalytic material exhibits a typical M6L8 structure with six exposed mononuclear copper centers, which maximizes the exposure of catalytic active sites, accelerates the approach of reactant molecules to the active sites and the desorption of products, and improves the selectivity of the target product. The strong copper-nitrogen bond ensures the stability of the catalyst during the reaction, prevents the aggregation of metal particles during the catalytic process due to the progress of the reaction, and has a high reusability.

[0032] 2. When the organic ligand is potassium tris(1H-imidazolyl)borohydride and the metallic copper salt is copper nitrate, the BIF-29 catalytic material with a typical M6L8 structure prepared in this invention exhibits strong reactivity. When participating in the electrocatalytic carbon dioxide reduction reaction, the electrocatalytic carbon dioxide reduction conversion efficiency of this octahedral BIF-29 catalytic material is as high as 93.7%.

[0033] 3. Compared with traditional copper-based MOFs, the octahedral BIF-29 catalytic material prepared in this invention can be used directly as a catalyst for the electrocatalytic carbon dioxide reduction reaction without any additional treatment (such as heat treatment), and the catalyst structure remains unchanged before and after the reaction. Furthermore, the octahedral BIF-29 catalytic material prepared in this invention exhibits better catalytic performance (93.7% CO2 conversion) in the electrocatalytic carbon dioxide reduction reaction than traditional copper-based MOFs (55.3% CO2 conversion). BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0035] Figure 1 This is a schematic structural diagram of a pneumatic continuous reaction device according to Example 1 of the present invention, comprising a reaction line, syringe A, syringe B, syringe C, a mixer, a reaction zone, and a collection device;

[0036] Figure 2 This is a structural diagram of the octahedral BIF-29 catalytic material prepared in Example 2 of the present invention, including metallic copper connected to nitrogen in the organic ligand to form a micro two-dimensional planar structure;

[0037] Figure 3 This is the X-ray powder diffraction pattern (PXRD) of the octahedral BIF-29 catalytic material prepared in Example 2 of the present invention;

[0038] Figure 4 This is a scanning electron microscope (SEM) image of the octahedral BIF-29 catalytic material prepared in Example 2 of the present invention;

[0039] Figure 5 This is a transmission electron microscope (TEM) image of the octahedral BIF-29 catalytic material prepared in Example 2 of the present invention;

[0040] Figure 6 The X-ray powder diffraction patterns (PXRD) of the octahedral BIF-29 catalytic material prepared in Example 2 of the present invention before and after spraying on the gas diffusion layer;

[0041] Figure 7 This is a scanning electron microscope (SEM) image of the octahedral BIF-29 catalytic material prepared in Example 2 of the present invention before spraying on the gas diffusion layer for reaction;

[0042] Figure 8 This is a scanning electron microscope (SEM) image of the octahedral BIF-29 catalytic material prepared in Example 2 of the present invention after spraying on the gas diffusion layer;

[0043] Figure 9 This is a scanning electron microscope (SEM) image of the octahedral BIF-29 catalyst material prepared in Example 3 of the present invention;

[0044] Figure 10 This is a transmission electron microscope (TEM) image of the octahedral BIF-29 catalytic material prepared in Example 3 of the present invention;

[0045] Figure 11 This is a scanning electron microscope (SEM) image of the octahedral BIF-29 catalytic material prepared in Example 4 of the present invention;

[0046] Figure 12 The X-ray powder diffraction pattern (PXRD) of the material obtained in Comparative Example 1 of the present invention is shown in FIG.

[0047] Figure 13 The X-ray powder diffraction pattern (PXRD) of the material obtained in Comparative Example 2 of the present invention is shown in FIG.

[0048] Figure 14 This is a scanning image of the traditional Cu-MOF in Comparative Example 3 of the present invention;

[0049] Figure 15 Graph showing selectivity at different applied potentials in a flow-type electrolytic cell in an application example of the present invention. DETAILED DESCRIPTION

[0050] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0051] All the raw materials in the examples are conventional reagents and commercially available products, and were used directly without further purification.

[0052] Example 1

[0053] This embodiment provides the assembly of a microfluidic pneumatic continuous reaction device, such as Figure 1 The microfluidic pneumatic continuous reaction apparatus includes syringes A, B, and C, a first injection tube, a second injection tube, a mixer, a tee, a third injection tube, an oven, a reaction tube, and a collection device. The first, second, and third injection tubes, as well as the reaction tube, are all transparent polytetrafluoroethylene hoses with an inner diameter of 2 mm and an outer diameter of 3 mm.

[0054] Syringe A is connected to the mixer via a first injection tube, and syringe B is connected to the mixer via a second injection tube. The mixer and collection device are connected via a reaction tube. An oven is located between the mixer and collection device, and the reaction tube passes through the oven; the oven is an electrically heated constant-temperature forced air drying oven used to heat the reaction tube. Syringe C is connected to the third injection tube, which is connected to the reaction tube via a tee located between the mixer and the heating device.

[0055] Example 2

[0056] This embodiment provides a continuous preparation method of octahedral BIF-29 catalytic material, using the microfluidic pneumatic continuous reaction device of Example 1, and the specific steps are as follows:

[0057] Step 1: Connect syringe A, syringe B, syringe C, a mixer, and an oven in sequence through a reaction line;

[0058] Step 2: Dissolve 0.825 g of KBH(im)3 ligand in 30 mL of N,N-dimethylacetamide and add it to syringe A; dissolve 1.875 g of copper nitrate trihydrate in 30 mL of methanol and add it to syringe B; add high-purity nitrogen gas to syringe C.

[0059] Step 3: The reaction temperature of the oven is 70°C.

[0060] Step 4, set the flow rate of syringe A to 100 μL / min, the flow rate of syringe B to 100 μL / min, and the flow rate of syringe C to 600 μL / min. The flow rate ratio of syringe A, syringe B, and syringe C is approximately 1:1:6; first, the organic ligand solution and the metal Cu salt solution in syringes A and B are mixed in a mixer to obtain a reaction mixed solution, and the nitrogen in syringe C is used to cut the continuously flowing reaction liquid into uniformly sized plugs, which are the reaction micro-locations.

[0061] Step 5: Collect the product using a product collection device in the microfluidic pneumatic continuous reaction, separate the product by centrifugation or filtration, and obtain the octahedral BIF-29 catalytic material.

[0062] Figure 2 This is a structural diagram of the obtained octahedral BIF-29 catalytic material, which includes metallic copper connected to nitrogen in organic ligands to form a micro two-dimensional planar structure; the octahedral BIF-29 catalytic material includes metallic copper salt and organic ligands. The octahedral BIF-29 catalytic material has an M6L8 structure, that is, six metallic copper sites are connected to eight organic ligands to form a cage-like structure with six exposed mononuclear copper centers, which are connected to the ligands through copper-nitrogen bonds inside, and the microscopic morphology presents an octahedral morphology.

[0063] Figure 3 Figure 2 is the PXRD spectrum of the obtained BIF-29 catalytic material. It can be seen that the BIF-29 catalytic material is consistent with the XRD simulation peak, proving that the material was successfully synthesized.

[0064] Figure 4 This is the SEM image of the BIF-29 catalytic material. It can be seen that the BIF-29 catalytic material has an octahedral morphology with a diameter of about 5-8 μm.

[0065] Figure 5 This is the TEM image of BIF-29 catalytic material, which confirms the octahedral structural characteristics of the material.

[0066] Example 3

[0067] The difference from Example 2 is that the organic ligand in step 2 is dissolved in a different organic solvent.

[0068] In this embodiment, in step 2, 0.825 g of KBH(im)3 ligand was dissolved in 30 mL of N,N-dimethylformamide and added to syringe A; 1.875 g of copper nitrate trihydrate was dissolved in 30 mL of methanol and added to syringe B; and high-purity nitrogen gas was added to syringe C.

[0069] Figure 9 This is the SEM of BIF-29 catalytic material.

[0070] Figure 10 TEM of BIF-29 catalytic material.

[0071] Example 4

[0072] The difference from Example 2 is that the metal copper salt in step 2 is dissolved in a different organic solvent.

[0073] In this embodiment, in step 2, 0.825 g of KBH(im)3 ligand was dissolved in 30 mL of N,N-dimethylacetamide and added to syringe A; 1.875 g of copper nitrate trihydrate was dissolved in 30 mL of ethanol and added to syringe B; and high-purity nitrogen gas was added to syringe C.

[0074] Figure 11 This is the SEM image of BIF-29 catalytic material.

[0075] Example 5

[0076] The difference from Example 2 is that the organic solvents in which the organic ligand and the metal copper salt are dissolved in step 2 are different.

[0077] In this embodiment, in step 2, 0.825 g of KBH(im)3 ligand was dissolved in 30 mL of N,N-dimethylformamide and added to syringe A; 1.875 g of copper nitrate trihydrate was dissolved in 30 mL of ethanol and added to syringe B; and high-purity nitrogen gas was added to syringe C.

[0078] Example 6

[0079] The difference from Example 2 is that the gas in the syringe C in step 2 is different.

[0080] In this embodiment, in step 2, 0.825 g of KBH(im)3 ligand was dissolved in 30 mL of N,N-dimethylacetamide and added to syringe A; 1.875 g of copper nitrate trihydrate was dissolved in 30 mL of methanol and added to syringe B; and air was added to syringe C.

[0081] Example 7

[0082] The difference from Example 2 is that the gas in the syringe C in step 2 is different.

[0083] In this embodiment, in step 2, 0.825 g of KBH(im)3 ligand was dissolved in 30 mL of N,N-dimethylacetamide and added to syringe A; 1.875 g of copper nitrate trihydrate was dissolved in 30 mL of methanol and added to syringe B; and argon gas was added to syringe C.

[0084] Comparative Example 1-Metal Copper Salts are Different

[0085] In this comparative example, the specific steps are the same as those in Example 2, except that in step 2, 0.825 g of KBH(im)3 ligand is dissolved in 30 mL of N,N-dimethylacetamide and added to syringe A; 1.41 g of copper acetate is dissolved in 30 mL of methanol and added to syringe B; and argon gas is added to syringe C.

[0086] Among them, the material finally prepared cannot form an octahedral morphology, such as Figure 12 As shown, the XRD diffraction peaks of the material do not correspond to the simulated peaks.

[0087] Comparative Example 2-Different organic ligands

[0088] In this comparative example, the specific steps are the same as those in Example 2, except that in step 2, 0.160 g of 1,3,5-benzenetricarboxylic acid ligand is dissolved in 30 mL of N,N-dimethylacetamide and added to syringe A; 1.875 g of copper nitrate trihydrate is dissolved in 30 mL of methanol and added to syringe B; and high-purity nitrogen gas is added to syringe C.

[0089] Among them, the final prepared material morphology is octahedral, such as Figure 13 As shown, if the XRD diffraction of the material matches the highest peaks of the simulation peaks, then it is an octahedral material.

[0090] Comparative Example 3-Traditional Cu-MOF

[0091] This comparative example provides a method for preparing traditional Cu-MOF using a traditional solvothermal method.

[0092] Step 1: First, dissolve 0.160g of 1,3,5-benzenetricarboxylic acid ligand in 30mL of methanol, which is recorded as solution A; dissolve 1.875g of copper nitrate trihydrate in 30mL of methanol, which is recorded as solution B; mix solution A and solution B and stir for five minutes, and then transfer them into the reactor.

[0093] Step 2: Set the oven temperature to 80°C for 10 hours; place the reactor in the oven with the program set, wait for the reaction to be completed, and then cool down naturally.

[0094] Step three: Collect the products after the reaction and separate them by centrifugation to obtain traditional Cu-MOF.

[0095] Figure 14 This is the SEM image of the obtained traditional Cu-MOF catalyst. It can be seen that the traditional Cu-MOF material also presents an octahedral morphology with a diameter of about 1 μm.

[0096] Application examples:

[0097] The octahedral BIF-29 catalytic material prepared in Example 2 was applied to the electrochemical carbon dioxide reduction reaction. The electrolytic cell used was a flow-type electrolytic cell consisting of three parts: a gas flow path, a cathode cell, and an anode cell. Each part was sealed with a polytetrafluoroethylene gasket. The cathode cell and the anode cell were separated by a Formazan FAB-PK-130 ion exchange membrane. YLS-30T gas diffusion carbon paper was used. 1M KOH was used as the electrolyte. High-purity carbon dioxide was introduced. The specific steps are as follows:

[0098] First, 10 mg of the octahedral BIF-29 catalytic material prepared in Example 2 was added to a mixed solution of 1 mL of isopropanol and 50 μL of perfluorosulfonic acid resin (Nafion, 5 wt.%), followed by ultrasonic treatment for 30 minutes to obtain a uniformly dispersed solution. Subsequently, 200 μL of the dispersion was transferred to a spray gun and evenly sprayed on a 2*2 gas diffusion carbon paper to obtain a catalytic material loading of approximately 0.5 mg cm -2 The prepared diffusion layer was transferred to a glove box overnight to allow it to dry completely; then the prepared gas diffusion layer was assembled between the gas chamber and the cathode electrolyte chamber of the flow-type electrolytic cell.

[0099] The assembled flow-type electrolytic cell was subjected to an electrocatalytic carbon dioxide reduction reaction performance test. Before the reaction, the carbon dioxide was introduced at a flow rate of 30 mL / min and the electrolyte was introduced at a flow rate of 20 mL / min. The products were analyzed by Shimadzu GC-2014 gas chromatography, and the selectivity of the electrocatalytic carbon dioxide reduction reaction was calculated according to formula (I). Figure 6 PXRD spectra of octahedral BIF-29 catalytic material sprayed on gas diffusion carbon paper before and after reaction; Figure 7-8 SEM images of octahedral BIF-29 catalyst material sprayed on gas diffusion carbon paper before and after reaction; thanks to the unique micro two-dimensional planar Cu-N4 structure (such as Figure 2 As shown in Figure 2, carbon dioxide molecules can be adsorbed on copper active sites with lower adsorption energy, making the BIF-29 catalytic material exhibit excellent catalytic performance in the electrocatalytic carbon dioxide reduction process. Figure 13 The carbon dioxide selectivity under different applied potentials is shown, and Table 2 gives the specific selectivity of carbon dioxide reduction under different applied potentials. It can be seen that the octahedral BIF-29 catalytic material has high carbon dioxide conversion performance at -1.2V to -1.4V, and the total conversion performance exceeds 90%.

[0100] Formula (I):

[0101]

[0102] where n x is the amount of substance of product x (mol), N is the number of electron transfers when generating product x (N is 2 when the product is CO, H2 and formate), F is the Faraday constant (96485C mol -1 ), Q is the amount of charge (C) that generates x transfer.

[0103] Experimental results and performance analysis

[0104] Octahedral BIF-29 catalytic materials were prepared according to the examples and comparative examples and used in the electrocatalytic carbon dioxide reduction reaction. The reaction activities of different catalytic materials were investigated, as shown in Table 1.

[0105] Table 1

[0106] Example Carbon dioxide conversion rate (%) Example 2 93.7 Example 3 84.6 Example 4 83.7 Example 5 86.4 Example 6 80.5 Example 7 83.2 Comparative Example 1 \ Comparative Example 2 45.2 Comparative Example 3 55.3

[0107] Among them, the “\” in Table 1 indicates that it was not tested. Due to the difference in the metal copper salt in Comparative Example 1, an octahedral material was not synthesized, and the electrocatalytic carbon dioxide reduction reaction of the material was not carried out. In Comparative Example 2, due to the difference in the organic ligand, when the ligand was 1,3,5-benzenetricarboxylic acid ligand, although an octahedral material was formed, its catalytic performance was not as good as that of the embodiment of the present invention. In Comparative Example 3, the traditional Cu-MOF material prepared by the traditional solvothermal method is an octahedral material, but its catalytic performance is also not as good as that of the embodiment of the present invention.

[0108] The octahedral BIF-29 catalytic material prepared in Example 2 was used for the electrocatalytic carbon dioxide reduction reaction, and the reaction activity of the catalytic material at different potentials was investigated, as shown in Table 2.

[0109] Table 2

[0110]

[0111]

[0112] The electrocatalytic carbon dioxide reduction reaction conditions are as follows: a carbon dioxide introduction rate of 30 mL / min, an electrolyte introduction rate of 20 mL / min, the reaction is carried out at room temperature, and the gas phase product is analyzed by chromatography after the reaction is carried out for ten minutes.

[0113] The carbon dioxide reduction comparison above demonstrates that the BIF-29 catalytic material prepared in the present invention, which has a typical M6L8 structure, exhibits strong reactivity when the organic ligand is potassium tris(1H-imidazolyl)borohydride and the metallic copper salt is copper nitrate. Therefore, the typical M6L8 structure of the octahedral BIF-29 catalytic material prepared in the present invention, with six exposed mononuclear copper centers at the periphery, facilitates the exposure of catalytically active sites, promoting the adsorption and activation of carbon dioxide at these sites, thereby significantly enhancing the catalyst's catalytic performance.

[0114] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. An octahedral BIF-29 catalytic material for electrocatalytic reduction of CO2, characterized in that: The octahedral BIF-29 catalytic material comprises a metal copper salt and an organic ligand. The octahedral BIF-29 catalytic material has an M6L8 structure, i.e., six metal copper sites are connected to eight organic ligands to form a cage-like structure, with six exposed mononuclear copper centers, which are internally connected to the ligands via copper-nitrogen bonds, and have an octahedral micromorphology. The organic ligand is potassium tris(1H-imidazolyl)borohydride, and the metal copper salt is copper nitrate. The molar ratio of copper element in the metal copper salt to the organic ligand is (0.5-3):

1. The continuous preparation method of the octahedral BIF-29 catalytic material comprises the following steps: Assembling a microfluidic pneumatic continuous reaction device, the microfluidic pneumatic continuous reaction device comprising syringe A, syringe B, syringe C, a reaction tube, a mixer, a heating device, and a collecting device, syringe A being pre-filled with an organic ligand solution, syringe B being pre-filled with a metal copper salt solution, and syringe C being pre-filled with gas; The organic ligand solution in syringe A and the metal copper salt solution in syringe B are mixed in a mixer to obtain a reaction mixture. The reaction mixture flows continuously in the reaction tube. The gas in syringe C is used to cut the continuously flowing reaction mixture into segments of uniform size. The segments are the reaction micro-locations. The segments in the reaction tube flow through a heating device with a set temperature, and the products are collected by a collecting device.

2. The octahedral BIF-29 catalytic material according to claim 1, characterized in that The diameter of the octahedral BIF-29 catalytic material is 2-5 μm.

3. The continuous preparation method of the octahedral BIF-29 catalytic material according to any one of claims 1 to 2, characterized in that: The following steps are involved: Assembling a microfluidic pneumatic continuous reaction device, the microfluidic pneumatic continuous reaction device comprising syringe A, syringe B, syringe C, a reaction tube, a mixer, a heating device, and a collecting device, syringe A being pre-filled with an organic ligand solution, syringe B being pre-filled with a metal copper salt solution, and syringe C being pre-filled with gas; The organic ligand solution in syringe A and the metal copper salt solution in syringe B are mixed in a mixer to obtain a reaction mixture. The reaction mixture flows continuously in the reaction tube. The gas in syringe C is used to cut the continuously flowing reaction mixture into segments of uniform size. The segments are the reaction micro-locations. The segments in the reaction tube flow through a heating device with a set temperature, and the products are collected by a collecting device.

4. The continuous preparation method according to claim 3, characterized in that In the microfluidic pneumatic continuous reaction device, syringe A and syringe B are respectively connected to a mixer, the mixer and the collection device are connected through a reaction tube, a heating device is provided between the mixer and the collection device, and the reaction tube passes through the heating device; syringe C is connected to the reaction tube, and the connection between syringe C and the reaction tube is located between the mixer and the heating device.

5. The continuous preparation method according to claim 4, characterized in that The microfluidic pneumatic continuous reaction device further comprises a tee, and the C syringe is connected to the reaction tube via the tee.

6. The continuous preparation method according to claim 5, characterized in that The reaction tube is a transparent polytetrafluoroethylene hose.

7. The continuous preparation method according to claim 5, characterized in that The reaction tube has an inner diameter of 1-3 mm and an outer diameter of 2-4 mm, and the difference between the outer diameter and the inner diameter is greater than 0.5 mm.

8. The continuous preparation method according to claim 3, characterized in that The metal copper salt is copper nitrate; and the organic ligand is potassium tris(1H-imidazolyl)borohydride.

9. The continuous preparation method according to claim 3, characterized in that The molar ratio of the copper element in the metallic copper salt to the organic ligand is (0.5-3):

1.

10. The continuous preparation method according to claim 3, characterized in that: The gas is selected from any one of argon, nitrogen or air.

11. The continuous preparation method according to claim 3, characterized in that: The reaction temperature of the heating device is 60-80°C.

12. The continuous preparation method according to claim 3, characterized in that: The organic ligand solution is an organic ligand dissolved in an organic solvent a.

13. The continuous preparation method according to claim 12, characterized in that: The organic solvent a is at least one of N,N-dimethylformamide and N,N-dimethylacetamide.

14. The continuous preparation method according to claim 3, characterized in that: The metal copper salt solution is a metal copper salt dissolved in an organic solvent b.

15. The continuous preparation method according to claim 14, characterized in that: The organic solvent b is at least one of acetone, methanol and ethanol.

16. The continuous preparation method according to claim 3, characterized in that: The concentration of the metal copper salt solution is 0.1-8 mol / L, and the concentration of the organic ligand solution is 0.05-0.5 mol / L.

17. The continuous preparation method according to claim 3, wherein The fluid flow rate in syringe A was 50-200 μL / min, the fluid flow rate in syringe B was 50-200 μL / min, and the fluid flow rate in syringe C was 400-1000 μL / min; The ratio of the fluid flow rates in syringe A, syringe B, and syringe C is 1:1:(5-20).

18. A working electrode for electrocatalytic reduction of CO2, characterized in that: The working electrode comprises a substrate and a catalyst supported on the substrate; the catalyst is selected from the octahedral BIF-29 catalytic material according to any one of claims 1-2 or the octahedral BIF-29 catalytic material prepared by the continuous preparation method according to any one of claims 3-17.

19. Use of the octahedral BIF-29 catalytic material according to any one of claims 1 to 2, or the octahedral BIF-29 catalytic material prepared according to the continuous preparation method according to any one of claims 3 to 17, or the working electrode according to claim 18 in electrocatalytic reduction of CO2.

20. A method for electrocatalytic reduction of CO2, characterized in that: The octahedral BIF-29 catalytic material according to any one of claims 1 to 2 is mixed with an organic solvent to obtain a dispersion, which is sprayed on a substrate. After drying, the dispersion is placed in an electrolytic cell, and carbon dioxide is introduced to perform an electrocatalytic reaction.

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