Water-phase ultrafast green preparation of bismuth-based metal organic framework and application of bismuth-based metal organic framework in carbon dioxide electroreduction

Abstract

The invention relates to the technical field of electrocatalytic reduction of carbon dioxide, and provides a water-phase ultrafast green preparation method of a bismuth-based metal organic framework, and the preparation method of the bismuth-based metal organic framework material comprises the following steps: taking bismuth nitrate pentahydrate as a bismuth source, taking trimesic acid as a ligand, and preparing the bismuth-based metal organic framework material through a surfactant-mediated sonochemistry method. A complex topological bismuth-based metal organic framework (CAU-17) is synthesized in water under an environmental condition. The synthesis method is rapid, environmentally friendly, low in cost and easy to operate, cetyltrimethylammonium bromide (CTAB) amphiphilic molecules are used as a structure inducer, removal (dehydration) of non-coordinated water is controlled, the deprotonation degree of ligands is improved, therefore, coordination and crystallization in an aqueous solution are adjusted, and by adjusting the dosage of the added CTAB, the deprotonation degree of the ligands is increased. And the crystal structure evolution from a preferentially generated compact sheet structure to a porous rod-shaped structure is realized. Meanwhile, the synthesized CAU-17 catalyst shows relatively high current density and Faraday efficiency in electrocatalytic reduction of carbon dioxide into formic acid, and has relatively good selectivity.

Description

[0001] The present invention belongs to the technical field of electrocatalytic reduction of carbon dioxide, and specifically relates to a preparation method of bismuth-based metal-organic framework CAU-17 and its application in the field of carbon dioxide electroreduction. Background Art

[0002] At present, with the continuous growth of global energy consumption and the continuous increase of greenhouse gas emissions, how to effectively reduce the concentration of carbon dioxide (CO2) in the atmosphere has become one of the key challenges in dealing with climate change and promoting sustainable development. As a promising carbon resource conversion technology, the electrocatalytic CO2 reduction reaction (CO2RR) can not only achieve the efficient reuse of CO2, but also be coupled with clean energy systems such as solar energy and wind energy to synthesize high-value chemicals and fuels under mild conditions. Especially, formic acid and its salts have become important target products in CO2RR due to their good hydrogen storage capacity, high energy density and wide industrial application value. However, problems such as high overpotential, low selectivity and complex product distribution still exist in this reaction process, and the product purity is often sacrificed while increasing the reaction current density. Therefore, developing a catalyst that can achieve high selectivity and high stability at high current density is one of the core scientific issues for the large-scale application of CO2 electroreduction.

[0003] As a new type of multifunctional electrocatalyst system, bismuth-based metal-organic framework (Bi-MOFs) materials exhibit significant advantages in the electrocatalytic reduction of carbon dioxide due to their adjustable structure, ordered pores, and high electrocatalytic activity. Compared with traditional bismuth-based catalysts, Bi-MOFs not only retain the excellent properties of bismuth elements in inhibiting the hydrogen evolution reaction and promoting the formation of formic acid but also further enhance the distribution of active sites and the ability to regulate the electronic structure of the materials. The highly ordered and open framework structure of MOF provides more mass transfer channels for CO2 molecules, which is conducive to the stable adsorption and effective conversion of reaction intermediates. More importantly, the preparation process of Bi-MOFs materials is fast, green, and environmentally friendly. In recent years, with the development of green synthesis processes such as low-temperature hydrothermal method, room-temperature in-situ self-assembly, and microwave-assisted synthesis, the preparation efficiency of Bi-MOFs has been significantly improved, while avoiding the overuse of high-temperature calcination or organic solvents, which is in line with the concepts of clean chemistry and sustainable development. This low-energy-consuming and pollution-free synthesis method not only greatly simplifies the preparation process but also improves the yield and structural homogeneity of the materials, which is conducive to large-scale production and industrial application. In addition, the types of ligands and reaction conditions in the synthesis process can be flexibly regulated, enabling Bi-MOFs to have good structural designability and targeted optimization of catalytic performance. Therefore, bismuth-based metal-organic framework materials not only have excellent electrocatalytic performance and high formic acid selectivity but also meet the comprehensive performance requirements of "efficient, green, and sustainable" in modern materials chemistry, and are a new catalytic system that promotes the resource conversion of CO2 towards high performance and environmental protection.

[0004] Based on the above research status, it is of great theoretical significance and industrial application value to seek a relatively fast, green, and environmentally friendly method to prepare bismuth-based metal-organic framework catalysts and use them for the electrocatalytic reduction of carbon dioxide to produce formate with high selectivity and high activity.. Summary of the Invention

[0005] The present invention provides an aqueous-phase ultrafast green preparation of bismuth-based metal-organic framework and its application in the electrocatalytic reduction of carbon dioxide. Using cetyltrimethylammonium bromide (CTAB) amphiphilic molecules as structure-inducing agents, the removal of non-coordinating water (dehydration) is controlled to increase the degree of deprotonation of ligands, thereby regulating coordination and crystallization in the aqueous solution. By adjusting the amount of CTAB added, the crystal structure evolution from a preferentially formed dense flake structure to a porous rod-like structure is achieved. CAU-17 with different crystal structures has different electrocatalytic carbon dioxide reduction performances. The preparation process of this catalyst is simple, fast, green, and environmentally friendly, the process conditions are easy to control, and it can achieve high selectivity for formic acid in the electrocatalytic reduction of carbon dioxide, while showing a relatively high partial current density.

[0006] To achieve the above object, the present invention provides the following technical solution: An aqueous-phase ultrafast green preparation method of bismuth-based metal-organic framework, comprising the following steps:

[0007] Step 1, dissolve bismuth nitrate pentahydrate in deionized water;

[0008] Step 2, dissolve trimesic acid organic ligand in deionized water;

[0009] Step 3, mix the solution formed in Step 2 with the solution formed in Step 1;

[0010] Step 4, add cetyltrimethylammonium bromide (CTAB) to the mixed solution in Step 3, and use ultrasonic-assisted solvent dispersion for mixing reaction;

[0011] Step 5, centrifuge and wash the bismuth-based metal-organic framework CAU-17 generated in Step 4 several times with anhydrous methanol, and place it in a vacuum oven for drying.

[0012] The bismuth-based metal-organic framework CAU-17 prepared by the above preparation method. This material will be used in electrocatalytic reactions.

[0013] The bismuth-based metal-organic framework CAU-17 prepared by the above preparation method. After this material is made into an electrode, it is used for electrocatalytic reduction of carbon dioxide.

[0014] Compared with the related technology, the beneficial effects of the present invention are as follows:

[0015] 1. The bismuth-based metal-organic framework CAU-17 prepared by the present invention is prepared by a surfactant-mediated sonochemical method to prepare bismuth-based metal-organic framework CAU-17 with different crystal structures. The preparation process is simple, fast, green, and environmentally friendly. The process conditions are easy to control, easy to operate, and easy to promote and use.

[0016] 2. The obtained bismuth-based metal-organic framework CAU-17 of the present invention has a highly ordered and open framework structure, which provides more mass transfer channels for CO2 molecules, is conducive to the stable adsorption and effective conversion of reaction intermediates, and can catalyze the electroreduction of carbon dioxide to formic acid with high activity and high selectivity. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only one embodiment of the present invention. For those of ordinary skill in the art, without creative efforts, other implementation drawings can be obtained according to the provided drawings.

[0018] Figure 1It is a schematic diagram of the aqueous-phase ultrafast green preparation process of bismuth-based metal-organic framework CAU-17 provided by the present invention.

[0019] Figure 2 It is the X-ray diffraction pattern of bismuth-based metal-organic framework CAU-17 prepared in Examples 1-5 and Comparative Example 1 of the present invention.

[0020] Figure 3 It is the scanning electron microscope image of bismuth-based metal-organic framework CAU-17 prepared in Examples 1-5 and Comparative Example 1 of the present invention, where (a) CAU-17-CTAB-5mg; (b) CAU-17-CTAB-10mg; (c) CAU-17-CTAB-25mg; (d) CAU-17-CTAB-50mg; (e) CAU-17-CTAB-100mg; (f) CAU-17-Plate.

[0021] Figure 4 It is the nitrogen adsorption isotherm diagram of bismuth-based metal-organic framework CAU-17 prepared in Example 3 and Comparative Example 1 of the present invention.

[0022] Figure 5 It is the pore size distribution diagram of bismuth-based metal-organic framework CAU-17 prepared in Example 3 and Comparative Example 1 of the present invention.

[0023] Figure 6 It is the Raman spectrum diagram of bismuth-based metal-organic framework CAU-17 prepared in Example 3 and Comparative Example 1 of the present invention.

[0024] Figure 7 It is the field emission electron microscope image and the distribution diagrams of bismuth, carbon, and oxygen elements of bismuth-based metal-organic framework CAU-17 prepared in Example 3 and Comparative Example 1 of the present invention, where (a) CAU-17-CTAB-Plate; (b) CAU-17-CTAB-25mg;.

[0025] Figure 8 It is the linear sweep voltammetry (LSV) diagram of the electroreduction of carbon dioxide by bismuth-based metal-organic framework CAU-17 prepared in Examples 1-5 and Comparative Example 1 of the present invention in an H-type electrolytic cell.

[0026] Figure 9 It is the bar chart of the Faraday efficiency (FE) of the electroreduction of carbon dioxide to formic acid by bismuth-based metal-organic framework CAU-17 prepared in Examples 1-5 and Comparative Example 1 of the present invention in an H-type electrolytic cell.

[0027] Figure 10 It is the partial current density curve diagram of the electroreduction of carbon dioxide to formic acid by bismuth-based metal-organic framework CAU-17 prepared in Examples 1-5 and Comparative Example 1 of the present invention in an H-type electrolytic cell.

[0028] Figure 11 It is the linear sweep voltammetry (LSV) curve of the bismuth-based metal-organic framework CAU-17 prepared in Example 3 and Comparative Example 1 of the present invention for the electroreduction of carbon dioxide in a flow-through electrolytic cell.

[0029] Figure 12 It is the bar graph of the Faraday efficiency (FE) for the electroreduction of carbon dioxide to formic acid by the bismuth-based metal-organic framework CAU-17 prepared in Example 3 and Comparative Example 1 of the present invention in a flow-through electrolytic cell.

[0030] Figure 13 It is the partial current density curve graph for the electroreduction of carbon dioxide to formic acid by the bismuth-based metal-organic framework CAU-17 prepared in Example 3 and Comparative Example 1 of the present invention in a flow-through electrolytic cell. Detailed implementation manners

[0031] The present invention will be further described below in conjunction with the accompanying drawings and examples:

[0032] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0033] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0035] Combined with Figure 1 As shown, the present invention provides an aqueous-phase ultrafast green preparation method for a bismuth-based metal-organic framework, including the following steps:

[0036] Step 1, dissolve bismuth nitrate pentahydrate in deionized water;

[0037] Step 2: Dissolve the trimesic acid organic ligand in deionized water;

[0038] Step 3: Mix the solution formed in Step 2 with the solution formed in Step 1;

[0039] Step 4: Add cetyltrimethylammonium bromide (CTAB) to the mixed solution in Step 3, and use ultrasonic assistance to disperse and mix the reaction in the solvent;

[0040] Step 5: Centrifuge and wash the bismuth-based metal-organic framework CAU-17 generated in Step 4 several times with anhydrous methanol, and place it in a vacuum oven for drying.

[0041] Based on the above technical solution, the ratio of deionized water in Step 1 and Step 2 is 1:(1 - 2), and the mass ratio of bismuth nitrate pentahydrate to trimesic acid organic ligand in Step 1 and Step 2 is (1 - 2):(1 - 5). Preferably, the ratio of deionized water in Step 1 and Step 2 is 1:1, and the mass ratio of bismuth nitrate pentahydrate to trimesic acid organic ligand is 1:5.

[0042] Based on the above technical solution, in Step 3, pour the solution in Step 2 into the solution in Step 1 for mixing.

[0043] Based on the above technical solution, the dosage of cetyltrimethylammonium bromide (CTAB) in Step 4 is 0 - 150 mg, the ultrasonic power is 200 - 400 watts, and the ultrasonic time is 5 - 60 minutes. Preferably, the ultrasonic power is 360 watts and the ultrasonic time is 10 minutes.

[0044] Based on the above technical solution, in Step 5, the centrifugation speed is 5000 - 10000 revolutions per minute, the centrifugation time is 5 - 10 minutes, the washing solvent is methanol or ethanol, the number of washing times is 3 - 6 times, the vacuum drying temperature is 50 - 80 °C, and the time is 8 - 24 h. Preferably, the centrifugation speed is 10000 revolutions per minute, the centrifugation time is 5 minutes, the washing solvent is methanol, the number of washing times is 3 times, the vacuum drying temperature is 60 °C, and the time is 12 h.

[0045] Second aspect, the present invention provides a method for the ultrafast green preparation of a bismuth-based metal-organic framework in an aqueous phase, which is prepared according to the method for the ultrafast green preparation of a bismuth-based metal-organic framework in an aqueous phase described in any one of the above embodiments.

[0046] Third aspect, the present invention provides an application of the bismuth-based metal-organic framework CAU-17 prepared by the method for the ultrafast green preparation of a bismuth-based metal-organic framework in an aqueous phase in the electroreduction of carbon dioxide to formic acid.

[0047] The present invention uses cetyltrimethylammonium bromide (CTAB) amphiphilic molecules as structure-inducing agents to control the removal (dehydration) of non-coordinating water, improve the degree of deprotonation of ligands, thereby regulating coordination and crystallization in aqueous solutions. By adjusting the amount of CTAB added, the crystal structure evolution from a preferentially formed dense flaky structure to a porous rod-like structure is achieved. CAU-17 with different crystal structures has different electrocatalytic carbon dioxide reduction performances. The preparation process of this catalyst is simple, rapid, green, and environmentally friendly, the process conditions are easy to control, and it can achieve high selectivity for formic acid in electrocatalytic carbon dioxide reduction, while showing a relatively high partial current density.

[0048] Example 1

[0049] This example provides a rapid and green aqueous-phase preparation method for bismuth-based metal-organic frameworks, including the following steps:

[0050] Step 1: Dissolve 150 mg of bismuth nitrate pentahydrate in 10 mL of deionized water;

[0051] Step 2: Dissolve 750 mg of trimesic acid organic ligand in 10 mL of deionized water;

[0052] Step 3: Pour the 10 mL solution in Step 2 into the 10 mL solution in Step 1 and mix thoroughly;

[0053] Step 4: Add 5 mg of cetyltrimethylammonium bromide (CTAB) to the mixed solution in Step 3 and use ultrasonic-assisted solvent dispersion mixing reaction. The ultrasonic power is 360 watts and the ultrasonic time is 10 minutes;

[0054] Step 5: Wash and centrifuge the bismuth-based metal-organic framework CAU-17 generated in Step 4. The centrifugation speed is 10,000 revolutions per minute and the centrifugation time is 5 minutes. The washing solvent is methanol and the number of washing times is 3 times. The vacuum drying temperature is 60 °C and the time is 12 h, finally obtaining the bismuth-based metal-organic framework CAU-17-CTAB-5 mg.

[0055] Example 2

[0056] The preparation method of this example is the same as that of Example 1, and the same parts are omitted. The difference from Example 1 is that in this example, in Step 4, the usage amount of cetyltrimethylammonium bromide (CTAB) is 10 mg, and finally the bismuth-based metal-organic framework CAU-17-CTAB-10 mg is obtained.

[0057] Example 3

[0058] The preparation method of this example is the same as that of Example 1, and the same parts are omitted. The difference from Example 1 is that in this example, in Step 4, the usage amount of cetyltrimethylammonium bromide (CTAB) is 25 mg, and finally the bismuth-based metal-organic framework CAU-17-CTAB-25 mg is obtained.

[0059] Example 4

[0060] The preparation method of this example is the same as that of Example 1, and the same parts are omitted. The difference from Example 1 is that in this example, in Step 4, the usage amount of cetyltrimethylammonium bromide (CTAB) is 50 mg, and finally the bismuth-based metal-organic framework CAU-17-CTAB-50 mg is obtained.

[0061] Example 5

[0062] The preparation method of this example is the same as that of Example 1, and the same parts are omitted. The difference from Example 1 is that in this example, in Step 4, the usage amount of cetyltrimethylammonium bromide (CTAB) is 100 mg, and finally the bismuth-based metal-organic framework CAU-17-CTAB-100 mg is obtained.

[0063] Comparative Example 1

[0064] Step 1: Dissolve 150 mg of bismuth nitrate pentahydrate in 10 mL of anhydrous methanol.

[0065] Step 2: Dissolve 750 mg of trimesic acid organic ligand in 10 mL of anhydrous methanol.

[0066] Step 3: Pour the 10 mL solution in Step 2 into the 10 mL solution in Step 1 and mix well.

[0067] Step 4: Ultrasonically assist the solvent dispersion and mixing reaction of the mixed solution in Step 3, with an ultrasonic power of 360 watts and an ultrasonic time of 40 minutes.

[0068] Step 5: Wash and centrifuge the bismuth-based metal-organic framework CAU-17 generated in Step 4, with a centrifuge speed of 10,000 revolutions per minute and a centrifuge time of 5 minutes. The washing solvent is methanol, and the number of washing times is 3 times. The vacuum drying temperature is 60 °C and the time is 12 h, and finally the bismuth-based metal-organic framework CAU-17-Plate is obtained.

[0069] In an H-type electrolytic cell, a three-electrode system is used for the carbon dioxide electroreduction performance test. The carbon paper loaded with the bismuth-based metal-organic framework CAU-17 prepared in Examples 1-5 and Comparative Example 1 is used as the working electrode, the saturated silver / silver chloride electrode is used as the reference electrode, and the platinum electrode is used as the counter electrode. With 0.5 mol·L -1A potassium bicarbonate solution is used as the electrolyte. A potentiostatic test is carried out. Before the test, carbon dioxide gas is introduced to saturate the electrolyte, and the flow rate of CO2 is maintained at 20 mL·min -1 , and the time is 30 min. The potential range during the test is -0.6 to -1.1 V (vs. RHE). The gaseous products generated by the reaction are detected by a gas chromatograph, and the liquid products are detected by a nuclear magnetic resonance spectrometer, and the Faraday efficiency is calculated therefrom.

[0070] In a flow-through electrolytic cell, a three-electrode system is used to test the carbon dioxide electroreduction performance. A gas diffusion electrode loaded with the bismuth-based metal-organic framework CAU-17 prepared in Examples 1-5 and Comparative Example 1 is used as the working electrode, a saturated silver / silver chloride electrode is used as the reference electrode, and nickel foam is used as the counter electrode. Using 1 mol·L -1 of potassium hydroxide solution as the electrolyte. A potentiostatic test is carried out, and the flow rate of CO2 is maintained at 20 mL·min -1 , and the electrolyte is circulated in the cathode chamber and the anode chamber at a rate of 20 mL min-1 by a peristaltic pump for 30 min. The potential range during the test is -0.7 to -1.3 V (vs. RHE). The gaseous products generated by the reaction are detected by a gas chromatograph, and the liquid products are detected by a nuclear magnetic resonance spectrometer, and the Faraday efficiency is calculated therefrom.

[0071] Figure 1 is the aqueous-phase ultrafast green preparation flow chart of the provided bismuth-based metal-organic framework CAU-17.

[0072] Figure 2 is the X-ray diffraction pattern of the bismuth-based metal-organic framework CAU-17 prepared in Examples 1-5 and Comparative Example 1 of the present invention. It can be seen from the figure that CAU-17 with 0, 5, 10, and 25 mg of CTAB shows similar diffraction patterns. The 50 and 100 mg samples show poorer crystallinity, indicating that the introduction of an appropriate amount of CTAB does not destroy the crystal structure of CAU-17, and the introduction of an excessive amount of CTAB will destroy the crystal structure of CAU-17.

[0073] Figure 3 is the scanning electron microscope image of the bismuth-based metal-organic framework CAU-17 prepared in Examples 1-5 and Comparative Example 1 of the present invention. Among them, Comparative Example 1 shows a dense flaky structure. With the increase in the amount of CTAB added, the crystal structure evolution from the preferentially generated dense flaky structure to the porous rod-like structure CAU-17 is realized. When the amount of CTAB is added to 25 mg, CAU-17 has a uniform short rod morphology. When the amount is 50 mg and 100 mg, CAU-17 changes from a rod shape to a fibrous shape, and structural collapse occurs.

[0074] Figure 4 and Figure 5They are the nitrogen adsorption isotherm diagrams and pore size distribution diagrams of the bismuth-based metal-organic framework CAU-17 prepared in Invention Example 3 and Comparative Example 1 respectively. It is shown that both CAU-17-CTAB-25mg and CAU-17-Plate have a mixed pore structure, and it can be confirmed that the pore structure is mainly microporous, and the mesopore size is about 1 nm. In addition, the specific surface area of the sample can be calculated by the BET model. The specific surface area of CAU-17-CTAB-25mg shows a significant increase compared with CAU-17-Plate, indicating that the appropriate introduction of CTAB can effectively improve the specific surface area of the material.

[0075] Figure 6 They are the Raman spectra of the bismuth-based metal-organic framework CAU-17 prepared in Invention Example 3 and Comparative Example 1. In the Raman spectra, both CAU-17-CTAB-25mg and CAU-17-Plate have basically the same chemical bonds and the same Bi-O bond, indicating that the appropriate introduction of CTAB will not destroy the original chemical bonds of CAU-17.

[0076] Figure 7 They are the field emission electron microscope images and the distribution diagrams of bismuth, carbon, and oxygen elements of the bismuth-based metal-organic framework CAU-17 prepared in Invention Example 3 and Comparative Example 1. CAU-17-Plate has a dense flaky morphology, and bismuth, carbon, and oxygen elements are evenly distributed; CAU-17-CTAB-25mg has a uniform short rod morphology, and bismuth, carbon, and oxygen elements are evenly distributed. It shows that the appropriate introduction of CTAB has a significant impact on the morphology of CAU-17.

[0077] Figure 8 They are the linear sweep voltammetry (LSV) diagrams of the electroreduction of carbon dioxide in the H-type electrolytic cell of the bismuth-based metal-organic framework CAU-17 prepared in Invention Examples 1-5 and Comparative Example 1. It is shown that CAU-17-CTAB-25mg has the largest current density and shows the lowest onset potential in the CO2-saturated electrolyte, indicating that the CO2RR on CAU-17-CTAB-25mg has the lowest reaction energy barrier and the highest catalytic activity, which is beneficial to improving the energy efficiency of the cathode reaction.

[0078] Figure 9 They are the bar graphs of the Faraday efficiency (FE) of the electroreduction of carbon dioxide to formic acid in the H-type electrolytic cell of the bismuth-based metal-organic framework CAU-17 prepared in Invention Examples 1-5 and Comparative Example 1. CAU-17-CTAB-25mg achieved a Faraday efficiency of higher than 90% for the formic acid product in a wide potential range of -0.7~-1.1 V vs. RHE, and the Faraday efficiency was as high as 96.8% at -0.9 V vs. RHE, which is higher than other examples and has extremely excellent selectivity for the formic acid product.

[0079] Figure 10 Figure 1 is the partial current density curve diagram of the electroreduction of carbon dioxide to formic acid by the bismuth-based metal-organic framework CAU-17 prepared in Examples 1-5 and Comparative Example 1 of the present invention in an H-type electrolytic cell. CAU-17-CTAB-25mg has the largest partial current density, which is greater than that of other examples, and has the best catalytic performance.

[0080] Figure 11 Figure 2 is the linear sweep voltammetry (LSV) curve diagram of the electroreduction of carbon dioxide by the bismuth-based metal-organic framework CAU-17 prepared in Example 3 and Comparative Example 1 of the present invention in a flow-type electrolytic cell. The current density of CAU-17-CTAB-25mg is significantly higher than that of CAU-17-Plate, meeting the industrial current density requirements. The starting potential of CAU-17-CTAB-25mg is lower, indicating that its CO2RR has a lower reaction energy barrier and higher catalytic activity.

[0081] Figure 12 Figure 3 is the bar chart of the Faraday efficiency (FE) of the electroreduction of carbon dioxide to formic acid by the bismuth-based metal-organic framework CAU-17 prepared in Example 3 and Comparative Example 1 of the present invention in a flow-type electrolytic cell. CAU-17-CTAB-25mg achieved a Faraday efficiency of higher than 95% for formic acid products in a wide potential range of -0.7 to -1.3V vs. RHE, which is greater than that of CAU-17-Plate and has more excellent catalytic performance.

[0082] Figure 13 Figure 4 is the partial current density curve diagram of the electroreduction of carbon dioxide to formic acid by the bismuth-based metal-organic framework CAU-17 prepared in Example 3 and Comparative Example 1 of the present invention in a flow-type electrolytic cell. CAU-17-CTAB-25mg has a larger partial current density, which is greater than that of CAU-17-Plate and has more excellent catalytic performance.

[0083] In summary, the bismuth-based metal-organic framework CAU-17 prepared by the present invention has a highly ordered and open framework structure, provides more mass transfer channels for CO2 molecules, is conducive to the stable adsorption and effective conversion of reaction intermediates, and can catalytically electroreduce carbon dioxide to prepare formic acid with high activity and high selectivity.

[0084] The present invention has been described above by way of example, but the present invention is not limited to the above specific embodiments. Any modification or variation based on the present invention falls within the scope of protection of the present invention.

Claims

1. An aqueous ultrafast green preparation of a bismuth-based metal-organic framework, characterized in that: The following steps are involved: Step 1, dissolving bismuth nitrate pentahydrate in deionized water; Step 2, dissolving the trimesic acid organic ligand in deionized water; Step 3, mixing the solution formed in step 2 with the solution formed in step 1; Step 4, adding cetyltrimethylammonium bromide (CTAB) to the mixed solution of step 3, and using ultrasound to assist the solvent dispersion and mixing reaction; Step 5: The bismuth-based metal organic framework CAU-17 generated in step 4 is centrifugally washed several times with anhydrous methanol and then placed in a vacuum oven for drying.

2. The method for preparing the bismuth-based metal organic framework CAU-17 according to claim 1, characterized in that: In step 1 and step 2, the mass ratio of bismuth nitrate pentahydrate to trimesic acid organic ligand is (1-2): (1-5).

3. The method for preparing the bismuth-based metal organic framework CAU-17 according to claim 1, characterized in that: In step 3, the solution of step 2 is poured into the solution of step 1 for mixing.

4. The method for preparing the bismuth-based metal organic framework CAU-17 according to claim 1, characterized in that: It is characterized in that In step 4, the amount of CTAB used is 0-150 mg.

5. The method for preparing the bismuth-based metal organic framework CAU-17 according to claim 1, characterized in that: In step 4, the ultrasonic power is 200-400 watts, and the ultrasonic time is 5-60 minutes.

6. The method for preparing the bismuth-based metal organic framework CAU-17 according to claim 1, characterized in that: In step 5, the centrifugal speed is 5000-10000 rpm, the centrifugal time is 5-10 minutes, the washing solvent is methanol or ethanol, the washing times are 3-6 times, the vacuum drying temperature is 50-80°C, and the time is 8-24 hours.

7. A bismuth-based metal organic framework CAU-17, characterized in that It is prepared according to the preparation method of the bismuth-based metal organic framework CAU-17 according to any one of claims 1 to 6.

8. The use of the bismuth-based metal organic framework CAU-17 as claimed in claim 7, characterized in that: The material will be used for electrocatalytic reactions.

9. The use of the bismuth-based metal organic framework CAU-17 as claimed in claim 8, characterized in that: The material is prepared into an electrode and used for electrocatalytic reduction of carbon dioxide.

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