A boron-containing copper-based three-dimensional metal-organic framework material and its preparation method and application

Abstract

The present invention discloses a boron-containing copper-based three-dimensional metal-organic framework material, its preparation method, and application, belonging to the field of fine chemical technology. A Zn-based MBON is prepared using a zinc salt, boric acid, and imidazole via a hydrothermal method. The zinc component is then completely replaced with copper to obtain a Cu-based MBON, i.e., a boron-containing copper-based three-dimensional metal-organic framework material. This material has a large specific surface area, forming a unique three-dimensional nanoflower-like structure. This prepared material is used as a catalyst in furfural electrohydrogenation and carbon dioxide reduction reactions, enhancing the diffusion efficiency of reactants (such as furfural and CO2) while promoting the rapid desorption of products (such as furfuryl alcohol and ethylene) through surface capillary action. It also inhibits the formation of byproducts caused by excessive reaction, thereby improving the selectivity of the target product.

Description

Technical Field

[0001] The present invention belongs to the technical field of fine chemical industry, and in particular relates to a boron-containing copper-based three-dimensional metal organic framework material, a preparation method thereof, and an application thereof. Background Art

[0002] Furfuryl alcohol is an important organic chemical and fine chemical raw material, typically produced through the advanced processing of furfural. The high-pressure hydrogen used in the traditional furfural hydrogenation process to produce furfuryl alcohol carries high transportation and storage costs, as well as potential explosion hazards. Furthermore, the harsh conditions required by this process result in high energy consumption. Therefore, the upcycling of biomass-derived small molecules through electric drive represents a promising green alternative, offering advantages such as mild conditions and easily regulated products.

[0003] Global climate change is a major existential challenge facing humanity. Using renewable, clean energy to capture and convert carbon dioxide through chemical methods offers a promising approach. The electrocatalytic carbon dioxide reduction reaction (CO2RR) has garnered increasing attention over the past few decades due to its ease of operation and environmental friendliness.

[0004] Metal-organic frameworks (MOFs) with exposed sites have shown great potential in catalytic reactions due to their unique structural tunability and high specific surface area. However, research on MOFs in furfural electrohydrogenation and carbon dioxide reduction reactions is limited, and there is still a lack of efficient catalyst designs that achieve high reaction activity while ensuring high selectivity for the target product and high Faradaic efficiency. Summary of the Invention

[0005] To address the shortcomings of the prior art, the present invention provides a boron-containing copper-based three-dimensional metal-organic framework (MOF) material, its preparation method, and its application. This material exhibits a large specific surface area, forming a unique three-dimensional nanoflower-like structure. Leveraging the structural characteristics of the graphene-like CuBO layer, the edges of the Cu-based MBON nanosheets expose numerous boron sites. Leveraging the strong interaction between boron and copper sites, the material exhibits excellent catalytic performance in furfural electrocatalysis and carbon dioxide reduction reactions. The 3D nanoflower-like structure of the assembled nanosheets provides abundant mesoporous and macroporous channels, enhancing the diffusion efficiency of reactants (such as furfural and CO2) while promoting the rapid desorption of products (such as furfuryl alcohol and ethylene) through surface capillary action. This structure also suppresses the formation of byproducts that can occur due to excessive reaction, thereby improving the selectivity of the target product.

[0006] This invention prepares a simple hydrothermal MOF structure (MBON), where MBON stands for Metal-Borate-Organic Framework. Using a Zn-based MBON as a precursor, the zinc in the Zn-based MBON is substituted with a copper salt to prepare a Cu-based MBON, which is then used in the electrocatalytic hydrogenation of furfural and carbon dioxide reduction reactions. The three-dimensional nanoflower-like hierarchical porous structure formed by the assembly of nanosheets maximizes the exposure of edge active sites and promotes mass transfer. In this three-dimensional nanoflower-like boron-containing copper-based catalytic material, imidazole is linked to graphene-like CuBO layers via Cu-N coordination to form a pillared layered network. The CuBO layers protect the organic linker from oxidation, and the unique structure and properties of the Cu-based MBON enable it to exhibit exceptionally high catalytic activity.

[0007] In order to achieve the above object, the technical solution of the present invention is:

[0008] In a first aspect, the present invention provides a boron-containing copper-based three-dimensional metal-organic framework material, wherein the boron-containing copper-based three-dimensional metal-organic framework material is a Cu-based MBON material, wherein MBON represents a metal-borate-organic framework;

[0009] The Cu-based MBON material has a layered columnar structure, in which imidazole connects graphene-like CuBO layers through Cu-N coordination to form a pillared layered network; the external morphology of the Cu-based MBON material is a three-dimensional nanoflower, which is formed by the assembly of nanosheets.

[0010] Specifically, the Cu-based MBON material is a pillared layered network structure, each layer is a graphene-like CuBO layer, and imidazole acts like a supporting pillar along the c-axis through Cu-N coordination to link the layered CuBO into a three-dimensional network framework.

[0011] In a second aspect, the present invention provides a method for preparing the above-mentioned boron-containing copper-based three-dimensional metal-organic framework material, comprising the following steps:

[0012] (1) Zn-based MBON was prepared by mixing zinc salt, imidazole and boric acid using a hydrothermal method;

[0013] (2) Using Zn-based MBON as a precursor, copper salt is used to replace the zinc in Zn-based MBON to prepare Cu-based MBON, thereby obtaining a boron-containing copper-based three-dimensional metal-organic framework material.

[0014] Boric acid is a key precursor for the construction of the six-membered boron-oxygen ring in Cu-based MBONs. Insufficient boric acid results in an incomplete framework, poor crystallinity, and even the inability to form the target structure. Imidazole is an organic ligand for MBONs. Its nitrogen atom coordinates with the metal ion, connecting the CuBO layers into columns along the c-axis through two distinct N sites. Imidazole forms stable coordination bonds with the metal ion, and the coordination mechanism is relatively simple, which facilitates the formation of a well-structured Cu-based MBON. Other organic ligands, such as trimesic acid, are not used because they contain three carboxyl groups. When carboxyl groups coordinate with metal ions, the coordination mechanisms are diverse and complex, potentially forming complexes with various structures, making it difficult to form the specific layered columnar framework structure required for Cu-based MBONs.

[0015] It should be noted that in the present invention, copper salts are used to replace the zinc in the precursor Zn-based MBON. If the replacement is incomplete, a MOF containing both copper and zinc will be formed. However, complete replacement results in a MOF containing only copper. Regardless of whether complete replacement is achieved, the resulting MOF can be used as a catalytic material. However, the Cu-based MBON obtained by complete replacement exhibits superior catalytic performance in catalytic applications.

[0016] In a third aspect, the present invention provides the use of the above-mentioned boron-containing copper-based three-dimensional metal-organic framework material in the electrocatalytic hydrogenation of aldehyde biomass derivatives to alcohol biomass derivatives or the electrocatalytic reduction of CO2. Preferably, the electrocatalytic hydrogenation of aldehyde biomass derivatives to alcohol biomass derivatives includes the electrocatalytic reduction of furfural.

[0017] In a fourth aspect, the present invention provides a method for electrocatalytic furfural reduction reaction, using the above-mentioned boron-containing copper-based three-dimensional metal-organic framework material as a catalyst.

[0018] In a fifth aspect, the present invention provides a method for electrocatalytic CO2 reduction reaction, using the above-mentioned boron-containing copper-based three-dimensional metal-organic framework material as a catalyst.

[0019] One or more of the above technical solutions have the following advantages or beneficial effects:

[0020] 1. The novel ultrathin, nanoflower-shaped, boron-containing copper-based three-dimensional metal-organic framework (MOF) prepared in this invention is derived from highly substituted zinc ions in MBONs (MBONs) with copper salts. The abundant exposed boron sites interact with the copper sites, making them excellent catalysts for the hydrogenation of furfural and carbon dioxide. The unique electron-rich structure of the adjacent, highly active boron sites, in concert with the copper sites, imparts high activity and selectivity to the copper-based MBONs. This material exhibits remarkable thermal stability, ensuring the stability of the nanoflower-shaped, boron-containing copper-based three-dimensional MOF catalyst during hydrogenation reactions. The catalyst structure remains unchanged before and after the reaction, resulting in high reusability.

[0021] 2. The present invention provides a novel nano-flower-shaped boron-containing copper-based three-dimensional metal-organic framework material. Compared with traditional copper-based metal-organic framework catalytic materials, the boron-containing copper-based three-dimensional metal obtained by the present invention is a three-dimensional nano-flower structure obtained by self-assembly of ultrathin nanosheets, which has a high degree of active site exposure, is beneficial to promoting the diffusion of reactant molecules on the material, and accelerating the adsorption and activation of substrate molecules at the catalytic active sites.

[0022] 3. The novel nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework material of the present invention was used for the hydrogenation conversion of furfural at a voltage of -0.25 to -0.3 V vs. RHE for 4 hours. The furfural conversion rate exceeded 90%, and the selectivity for furfuryl alcohol reached 90-100%. The material also maintained good furfural hydrogenation activity after multiple cycles.

[0023] 4. When the novel nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework material of the present invention is used for the carbon dioxide electrocatalytic reaction, the ethylene selectivity is higher than 64% at a voltage of -1.2 to -1.4 V vs. RHE, and the Faradaic efficiency is higher than 58%. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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.

[0025] Figure 1 The diffraction pattern (PXRD) of the three-dimensional nanoflower-shaped Zn-based MBON precursor prepared in Example 1 of the present invention;

[0026] Figure 2 This is a scanning electron microscope (SEM) image of the three-dimensional nanoflower-shaped Zn-based MBON precursor prepared in Example 1 of the present invention;

[0027] Figure 3 XRD comparison diagrams of the three-dimensional metal-organic framework materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention;

[0028] Figure 4 This is a scanning electron microscope (SEM) image of the nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework material prepared in Example 1 of the present invention;

[0029] Figure 5 This is a scanning electron microscope (SEM) image of the nanoflower-shaped boron-containing three-dimensional metal organic nanosheet Zn1Cu1-MBON prepared in Comparative Example 2 of the present invention;

[0030] Figure 6This is a comparison chart of the reaction performance of the nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework material prepared in Example 1 of the present invention for catalyzing furfural conversion at different reaction voltages;

[0031] Figure 7 This is a graph showing the reaction cycle stability of the nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework material prepared in Example 1 of the present invention during electrocatalytic furfural reduction;

[0032] Figure 8 This is a reaction performance diagram of the nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework material in Example 1 of the present invention for electrocatalytic carbon dioxide reduction at different reaction potentials. DETAILED DESCRIPTION

[0033] Explanation of terms involved:

[0034] MBON, also known as Zn-based MBON, refers to the metal component of MBON being zinc.

[0035] Cu-MBON, also known as Cu-based MBON, refers to the use of copper to completely replace the zinc components in MBON.

[0036] Zn1Cu1-MBON: The metal components in MBON contain both copper and zinc, which means that copper does not completely replace zinc.

[0037] "Three-dimensional metal-organic framework materials" are also known as "three-dimensional metal-organic nanosheet materials", or "three-dimensional metal-organic framework compounds", or "three-dimensional metal-organic framework catalytic materials".

[0038] In the present invention, unless otherwise specified, other test materials and instruments and equipment are conventional test materials in this field and can be purchased through commercial channels.

[0039] In a first typical embodiment, the present invention provides a boron-containing copper-based three-dimensional metal-organic framework material, wherein the boron-containing copper-based three-dimensional metal-organic framework material is a Cu-based MBON material, wherein MBON represents a metal-borate-organic framework;

[0040] The Cu-based MBON material has a layered columnar structure, in which imidazole connects graphene-like CuBO layers through Cu-N coordination to form a pillared layered network; the external morphology of the Cu-based MBON material is a three-dimensional nanoflower, which is formed by the assembly of nanosheets.

[0041] Specifically, the MBON material is a pillared layered network structure, each layer is a graphene-like CuBO layer. Imidazole acts like a supporting pillar, linking the layered CuBO into a three-dimensional network framework through Cu-N coordination along the c-axis.

[0042] In a second typical embodiment, the present invention provides a method for preparing the above-mentioned boron-containing copper-based three-dimensional metal-organic framework material, comprising the following steps:

[0043] (1) Zn-based MBON was prepared by mixing zinc salt, imidazole and boric acid using a hydrothermal method;

[0044] (2) Using Zn-based MBON as a precursor, copper salt is used to replace the zinc in MBON to prepare Cu-based MBON, thereby obtaining a boron-containing copper-based three-dimensional metal-organic framework material.

[0045] In one or more embodiments, in step (1), the mixing method of the zinc salt, the organic ligand (imidazole) and the boric acid is not particularly limited and can be carried out according to methods in the art.

[0046] Optionally, the specific preparation steps of Zn-based MBON are: zinc salt and boric acid are dissolved in a solvent to obtain solution a, imidazole is dissolved in a solvent to obtain solution b, solution a and solution b are mixed, subjected to hydrothermal reaction, centrifuged, washed, and dried to obtain the product.

[0047] In one or more embodiments, in step (1), the molar ratio of zinc salt, boric acid and imidazole is (1-3): (20-25): (7-8), preferably (1.5-2.5): (20-25): (7-7.5), such as 1.73: 22.5: 7.36 or 2.32: 22.5: 7.36. Insufficient boric acid will result in an incomplete framework structure, poor crystallinity, and even failure to form the target structure. Imidazole forms columns along the c-axis, and if imidazole is insufficient, the target structure cannot be formed. Therefore, only within a certain ratio range can a reasonable distribution of boric acid, imidazole and zinc be achieved, and a regular three-dimensional nanoflower-like framework structure be achieved.

[0048] In solution a, the ratio of zinc salt to solvent is (1-3 mmol):(10-20 mL); in solution b, the ratio of imidazole to solvent is (7-8 mmol):(10-20 mL). Within the above range, the zinc salt, boric acid, and imidazole are fully dissolved and mixed, facilitating subsequent reactions.

[0049] In one or more embodiments, in step (1), the zinc salt is one or more of zinc sulfate, zinc nitrate, zinc acetate and zinc chloride, such as zinc sulfate heptahydrate or zinc nitrate hexahydrate.

[0050] In one or more embodiments, in step (1), the solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, acetone, formic acid, methanol, ethanol and water.

[0051] In one or more embodiments, in step (1), solution a and solution b are mixed and stirred for 20-60 minutes to achieve sufficient mixing of the two to form a transparent solution.

[0052] In one or more embodiments, in step (1), during the hydrothermal reaction, the reaction temperature is 120-160°C, such as 120, 125, 130, 135, 140, 145, 150, 155, 160°C, etc., preferably 120-150°C, and more preferably 140-150°C. The heating rate is 3-10°C / min, such as 3, 4, 5, 6, 7, 8, 9, 10°C / min, etc. The reaction time is 5-10 hours, such as 5, 6, 7, 8, 9, 10 hours, etc., preferably 6-8 hours. Within this range, a three-dimensional nanoflower-shaped Zn-based MBON precursor can be better formed.

[0053] In one or more embodiments, in step (1), the present invention does not particularly limit the specific conditions of the washing, and the washing can be carried out according to methods in the art until the solution is clear. For example, anhydrous ethanol can be used for multiple washings.

[0054] In one or more embodiments, in step (1), the present invention does not particularly limit the drying conditions, and the drying can be carried out according to methods in the art. For example, vacuum drying can be used, with a drying temperature of 60-90° C. and a drying time of 5-24 hours.

[0055] In one or more embodiments, in step (2), the copper salt is one or more of copper sulfate, copper nitrate, copper acetate and copper chloride, such as copper nitrate trihydrate and copper chloride pentahydrate.

[0056] In one or more embodiments, in step (2), the concentration of the copper salt solution is 0.25-0.3 mol / L. If the concentration of the copper salt solution is too low, copper cannot completely replace zinc, resulting in a MOF structure in which copper and zinc coexist.

[0057] In one or more embodiments, in step (2), the molar ratio of the copper salt to the Zn-based MBON precursor is (0.06-0.4):0.2, such as 0.06:0.2, 0.07:0.2, 0.08:0.2, 0.10:0.2, 0.15:0.2, 0.18:0.2, 0.2:0.2, 0.22:0.2, 0.25:0.2, 0.28:0.2, 0.3:0.2, 0.32:0.2, 0.35:0.2, 0.38:0.2, 0.4:0.2, etc., preferably (0.1-0.35):0.2, more preferably (0.25-0.35):0.2, more preferably (0.25-0.3):0.2, and most preferably 0.3:0.2. If the amount of copper salt used is too low, the zinc substitution will be incomplete, resulting in a MOF structure in which copper and zinc coexist, which is not conducive to the subsequent catalytic reaction.

[0058] In one or more embodiments, in step (2), the reaction temperature is 10-80°C, such as 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, etc., but not limited to the above values, preferably 20-35°C, and most preferably room temperature (25°C); the reaction time is 10-30 min, such as 10 min, 15 min, 20 min, 25 min, 30 min, etc., but not limited to the above values, and preferably 10-15 min. Within this range, copper can better replace zinc.

[0059] In a third exemplary embodiment, the present invention provides the use of the above-mentioned boron-containing copper-based three-dimensional metal-organic framework material in the electrocatalytic hydrogenation of aldehyde biomass derivatives to produce alcohol biomass derivatives or the electrocatalytic reduction of CO2. Preferably, the electrocatalytic hydrogenation of aldehyde biomass derivatives to produce alcohol biomass derivatives includes the electrocatalytic reduction of furfural.

[0060] In a fourth typical embodiment, the present invention provides a method for electrocatalytic furfural reduction reaction, using the above-mentioned boron-containing copper-based three-dimensional metal-organic framework material as a catalyst.

[0061] The method specifically includes: using a three-electrode system, wherein the working electrode includes a substrate and the boron-containing copper-based three-dimensional metal-organic framework material; the reference electrode is a mercury / mercury oxide (Hg / HgO) reference electrode; the counter electrode is a platinum sheet electrode, and electrochemical hydrogenation is performed using the reference electrode and the counter electrode.

[0062] In one or more embodiments, the electrolyte is a KOH solution, and the concentration of the KOH solution is 0.8 to 1.2 mol / L, such as 0.8, 0.9, 1.0, 1.1, 1.2 mol / L, preferably 1 mol / L. The voltage of furfural electrocatalysis is -0.15 to -0.4 V vs. RHE, such as -0.15 V vs. RHE, -0.2 V vs. RHE, -0.25 V vs. RHE, -0.3 V vs. RHE, -0.35 V vs. RHE, -0.4 V vs. RHE, preferably -0.25 to -0.3 V vs. RHE, and most preferably -0.3 V vs. RHE. The reaction time is 2-6 h, preferably 3-5 h. Within the above range, it is more conducive to the progress of electrocatalysis and more conducive to obtaining high conversion rate and selectivity.

[0063] In a fifth typical embodiment, the present invention provides a method for electrocatalytic CO2 reduction reaction, using the above-mentioned boron-containing copper-based three-dimensional metal-organic framework material as a catalyst.

[0064] The method specifically involves using a three-electrode (flow cell) system. The working electrode comprises a substrate and a catalyst material loaded with the nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework compound; the reference electrode is a mercury / mercuric oxide (Hg / HgO) reference electrode; and the counter electrode is a platinum wire electrode. CO2 is introduced to perform electrochemical hydrogenation. The product can be analyzed in real time by online gas chromatography.

[0065] In one or more embodiments, the electrolyte is a KOH solution having a concentration of 0.8 to 1.2 mol / L, such as 0.8, 0.9, 1.0, 1.1, or 1.2 mol / L, preferably 1 mol / L. The voltage for CO2 electrocatalysis is -0.8 to -1.5 V vs. RHE, preferably -1 to -1.5 V vs. RHE, more preferably -1.2 to -1.4 V vs. RHE, and most preferably -1.3 V vs. RHE. Within this range, electrocatalytic efficiency is more effectively improved.

[0066] 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.

[0067] Example 1:

[0068] A method for preparing a novel nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework material comprises the following steps:

[0069] Step 1, preparation of precursor: 1.73 mmol of zinc nitrate hexahydrate as zinc salt and 22.5 mmol of boric acid were added to 15 mL of deionized water to obtain solution a; 7.36 mmol of imidazole as organic ligand was added to 15 mL of deionized water to obtain solution b;

[0070] Solution a and solution b were mixed, stirred for 30 minutes, transferred to a polytetrafluoroethylene reactor, heated to 150°C, and reacted for 6 hours. After the reaction was completed, the temperature was cooled to room temperature, and the precipitate was centrifuged and removed. After washing with anhydrous ethanol three times, it was dried at 80°C for 12 hours to obtain a white powder, which is a three-dimensional nanoflower-shaped Zn-based MBON precursor.

[0071] Step 2: Prepare a 0.3 mol / L copper salt solution, take 1.45 g of copper nitrate trihydrate and add 20 mL of deionized water, then mix 0.1 g (0.2 mol) of the three-dimensional nanoflower-shaped Zn-based MBON precursor obtained in step 1 with the copper salt solution in step 2, and let it react at room temperature for 10 minutes. After the reaction is completed, filter and obtain a blue precipitate, which is a new nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework material.

[0072] Figure 1 This is the PXRD pattern of the new three-dimensional nanoflower-like Zn-based MBON precursor. By observing the XRD pattern and simulated peak diagram of the MBON sample, it can be proved that the pure phase of MBON has been successfully prepared.

[0073] Figure 2 This is the SEM spectrum of the new three-dimensional nanoflower-like Zn-based MBON catalytic material. It can be seen that the crystal structure of MBON is layered, and its arrangement forms a unique three-dimensional flower-like layered structure with macroscopic pores, which is conducive to proton transfer.

[0074] Figure 3 Comparative XRD patterns of the novel boron-containing copper-based nanoflower-shaped three-dimensional metal-organic framework prepared in Example 1 of the present invention, the MBON prepared in Comparative Example 1, and the Cu1Zn1-MBON prepared in Comparative Example 2 confirm that the characteristic peak of the MBON sample at approximately 12° has almost disappeared in the catalytic Cu-MBON, indicating that Cu ions may have completely replaced Zn ions. Furthermore, it was found that the characteristic peak of Zn ions in the Cu1Zn1-MBON was not completely replaced by Cu, as shown by XPS analysis showing a Cu:Zn ratio of 1:1.

[0075] Figure 4 This is the SEM spectrum of the novel three-dimensional nanoflower Cu-based MBON catalytic material prepared in Example 1. Figure 4 and Figure 2By comparison, it can be clearly seen that after copper salt replacement, the material still has a three-dimensional nanoflower-like sheet structure, and the framework structure of the MOF material has not changed.

[0076] Example 2:

[0077] A method for preparing a novel nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework material comprises the following steps:

[0078] Here are the steps:

[0079] Step 1: Preparation of precursor: 1.73 mmol of zinc nitrate hexahydrate as a zinc salt and 22.5 mmol of boric acid were added to 15 mL of N,N-dimethylformamide to obtain solution a; 7.36 mmol of imidazole as an organic ligand was added to 15 mL of N,N-dimethylformamide to obtain solution b;

[0080] Solution a and solution b were mixed, stirred for 30 minutes, transferred to a polytetrafluoroethylene reactor, heated to 150°C, and reacted for 6 hours. After the reaction was completed, the temperature was cooled to room temperature, and the precipitate was centrifuged and removed. After washing with anhydrous ethanol three times, it was dried at 80°C for 12 hours to obtain a white powder, which is a three-dimensional nanoflower-shaped Zn-based MBON precursor.

[0081] Step 2: Prepare a 0.3 mol / L copper salt solution, take 1.45 g of copper nitrate trihydrate and add 20 mL of deionized water, then mix 0.1 g of the three-dimensional nanoflower-shaped Zn-based MBON precursor obtained in step 1 with the copper salt solution in step 2, and let it react at room temperature for 10 minutes. After the reaction is completed, filter and obtain a blue precipitate, which is a new nanoflower-shaped boron-containing copper-based three-dimensional metal organic nanosheet material.

[0082] Example 3:

[0083] A method for preparing a novel nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework material comprises the following steps:

[0084] Step 1, preparation of precursor: Preparation of precursor: 1.73 mmol of zinc nitrate hexahydrate as zinc salt and 22.5 mmol of boric acid were added to 15 mL of deionized water to obtain solution a; 7.36 mmol of imidazole as organic ligand was added to 15 mL of deionized water to obtain solution b;

[0085] Solution a and solution b were mixed, stirred for 30 minutes, transferred to a polytetrafluoroethylene reactor, heated to 150°C, and reacted for 8 hours. After the reaction was completed, the temperature was cooled to room temperature, and the precipitate was centrifuged and removed. After washing with anhydrous ethanol three times, it was dried at 80°C for 12 hours to obtain a white powder, which is a three-dimensional nanoflower-shaped Zn-based MBON precursor.

[0086] Step 2: Prepare a 0.3 mol / L copper salt solution, take 1.45 g of copper nitrate trihydrate and add 20 mL of deionized water, then mix 0.1 g of the three-dimensional nanoflower-shaped Zn-based MBON precursor obtained in step 1 with the copper salt solution in step 2, and let it react at room temperature for 10 minutes. After the reaction is completed, filter and obtain a blue precipitate, which is a new nanoflower-shaped boron-containing copper-based three-dimensional metal organic nanosheet material.

[0087] Example 4:

[0088] A method for preparing a novel nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework material comprises the following steps:

[0089] Step 1, preparation of precursor: 1.73 mmol of zinc nitrate hexahydrate as zinc salt and 22.5 mmol of boric acid were added to 15 mL of deionized water to obtain solution a; 7.36 mmol of imidazole as organic ligand was added to 15 mL of deionized water to obtain solution b;

[0090] Solution a and solution b were mixed, stirred for 30 minutes, transferred to a polytetrafluoroethylene reactor, heated to 150°C, and reacted for 6 hours. After the reaction was completed, the temperature was cooled to room temperature, and the precipitate was centrifuged and removed. After washing with anhydrous ethanol three times, it was dried at 80°C for 12 hours to obtain a white powder, which is a three-dimensional nanoflower-shaped Zn-based MBON precursor.

[0091] Step 2: Prepare a 0.3 mol / L copper salt solution, take 1.45 g of copper nitrate trihydrate and add 20 mL of deionized water, then mix 0.1 g of the three-dimensional nanoflower-shaped Zn-based MBON precursor obtained in step 1 with the copper salt solution in step 2, and let it react at room temperature for 30 minutes. After the reaction is completed, filter and obtain a blue precipitate, which is a new nanoflower-shaped boron-containing copper-based three-dimensional metal organic nanosheet material.

[0092] Example 5:

[0093] A method for preparing a novel nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework material comprises the following steps:

[0094] Step 1, preparation of precursor: 2.32 mmol of zinc nitrate hexahydrate as a zinc salt and 22.5 mmol of boric acid were added to 15 mL of deionized water to obtain solution a; zinc nitrate hexahydrate as a nickel salt was added to 15 mL of deionized water to obtain solution a; 7.36 mmol of imidazole as an organic ligand was added to 15 mL of deionized water to obtain solution b;

[0095] Solution a and solution b were mixed, stirred for 30 minutes, transferred to a polytetrafluoroethylene reactor, heated to 150°C, and reacted for 6 hours. After the reaction was completed, the temperature was cooled to room temperature, and the precipitate was centrifuged and removed. After washing with anhydrous ethanol three times, it was dried at 80°C for 12 hours to obtain a white powder, which is a three-dimensional nanoflower-shaped Zn-based MBON precursor.

[0096] Step 2: Prepare a 0.3 mol / L copper salt solution, take 1.45 g of copper nitrate trihydrate and add 20 mL of deionized water, then mix 0.1 g of the three-dimensional nanoflower-shaped Zn-based MBON precursor obtained in step 1 with the copper salt solution in step 2, and let it react at room temperature for 10 minutes. After the reaction is completed, filter and obtain a blue precipitate, which is a new nanoflower-shaped boron-containing copper-based three-dimensional metal organic nanosheet material.

[0097] Example 6:

[0098] A method for preparing a novel nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework material comprises the following steps:

[0099] Step 1, preparation of precursor: 1.73 mmol of zinc nitrate hexahydrate as zinc salt and 22.5 mmol of boric acid were added to 15 mL of deionized water to obtain solution a; 7.36 mmol of imidazole as organic ligand was added to 15 mL of deionized water to obtain solution b;

[0100] Solution a and solution b were mixed, stirred for 30 minutes, transferred to a polytetrafluoroethylene reactor, heated to 120°C, and reacted for 6 hours. After the reaction was completed, the temperature was cooled to room temperature, and the precipitate was centrifuged and removed. After washing with anhydrous ethanol three times, it was dried at 80°C for 12 hours to obtain a white powder, which is a three-dimensional nanoflower-shaped Zn-based MBON precursor.

[0101] Step 2: Prepare a 0.3 mol / L copper salt solution, take 1.45 g of copper nitrate trihydrate and add 20 mL of deionized water, then mix 0.1 g of the three-dimensional nanoflower-shaped Zn-based MBON precursor obtained in step 1 with the copper salt solution in step 2, and let it react at room temperature for 10 minutes. After the reaction is completed, filter and obtain a blue precipitate, which is a new nanoflower-shaped boron-containing copper-based three-dimensional metal organic nanosheet material.

[0102] Example 7:

[0103] A method for preparing a novel nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework material comprises the following steps:

[0104] Step 1, preparation of precursor: 1.73 mmol of zinc sulfate heptahydrate as zinc salt and 22.5 mmol of boric acid were added to 15 mL of deionized water to obtain solution a; 7.36 mmol of imidazole as organic ligand was added to 15 mL of deionized water to obtain solution b;

[0105] Solution a and solution b were mixed, stirred for 30 minutes, transferred to a polytetrafluoroethylene reactor, heated to 150°C, and reacted for 6 hours. After the reaction was completed, the temperature was cooled to room temperature, and the precipitate was centrifuged and removed. After washing with anhydrous ethanol three times, it was dried at 80°C for 12 hours to obtain a white powder, which is a three-dimensional nanoflower-shaped Zn-based MBON precursor.

[0106] Step 2: Prepare a 0.3 mol / L copper salt solution, take 1.45 g of copper nitrate trihydrate and add 20 mL of deionized water, then mix 0.1 g of the three-dimensional nanoflower-shaped Zn-based MBON precursor obtained in step 1 with the copper salt solution in step 2, and let it react at room temperature for 10 minutes. After the reaction is completed, filter and obtain a blue precipitate, which is a new nanoflower-shaped boron-containing copper-based three-dimensional metal organic nanosheet material.

[0107] Example 8:

[0108] A method for preparing a novel nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework material comprises the following steps:

[0109] Step 1, preparation of precursor: 2.32 mmol of zinc nitrate hexahydrate as zinc was added together with 22.5 mmol of boric acid in 15 mL of deionized water to obtain solution a; 7.36 mmol of imidazole as an organic ligand was added to 15 mL of deionized water to obtain solution b;

[0110] Solution a and solution b were mixed, stirred for 30 minutes, transferred to a polytetrafluoroethylene reactor, heated to 150°C, and reacted for 6 hours. After the reaction was completed, the temperature was cooled to room temperature, and the precipitate was centrifuged and removed. After washing with anhydrous ethanol three times, it was dried at 80°C for 12 hours to obtain a white powder, which is a three-dimensional nanoflower-shaped Zn-based MBON precursor.

[0111] Step 2: Prepare 0.3 mol / L copper salt solution, take 1.5 g of copper chloride pentahydrate and add 20 mL of deionized water, then mix 0.1 g of the three-dimensional nanoflower-shaped Zn-based MBON precursor obtained in step 1 with the copper salt solution in step 2, and let it react at room temperature for 10 minutes. After the reaction is completed, filter and obtain a blue precipitate, which is a new nanoflower-shaped boron-containing copper-based three-dimensional metal organic nanosheet material.

[0112] Comparative Example 1

[0113] A novel method for preparing a novel nano-flower-shaped boron-containing zinc-based three-dimensional metal organic nanosheet material is carried out according to step 1 of Example 1 to obtain MBON, whose morphology is as follows Figure 2 shown.

[0114] Comparative Example 2:

[0115] A method for preparing a novel nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework material comprises the following steps:

[0116] Step 1, preparation of precursor: 1.73 mmol of zinc nitrate hexahydrate as zinc salt and 22.5 mmol of boric acid were added to 15 mL of deionized water to obtain solution a; 7.36 mmol of imidazole as organic ligand was added to 15 mL of deionized water to obtain solution b;

[0117] Solution a and solution b were mixed, stirred for 30 minutes, transferred to a polytetrafluoroethylene reactor, heated to 150°C, and reacted for 6 hours. After the reaction was completed, the temperature was cooled to room temperature, and the precipitate was centrifuged and removed. After washing with anhydrous ethanol three times, it was dried at 80°C for 12 hours to obtain a white powder, which is a three-dimensional nanoflower-shaped Zn-based MBON precursor.

[0118] Step 2: Prepare 0.06 mol / L copper salt solution, take 0.29 g copper nitrate trihydrate and add 20 mL deionized water, then mix 0.1 g (0.2 mol) of the three-dimensional nanoflower-shaped Zn-based MBON precursor obtained in step 1 with the copper salt solution in step 2, and let it react at room temperature for 10 minutes. After the reaction is completed, filter and obtain a blue precipitate, which is the new nanoflower-shaped boron-containing three-dimensional metal organic nanosheet material Zn1Cu1-MBON, whose morphology is as follows: Figure 5 shown.

[0119] Comparative Example 3:

[0120] The difference from Example 1 is that only boric acid is added without imidazole during the synthesis of MBON in step 1, which specifically includes:

[0121] 1.73 mmol of zinc nitrate hexahydrate was taken as the zinc salt and 22.5 mmol of boric acid was added to 15 mL of deionized water to obtain solution a. The solution was stirred for 30 minutes, transferred to a polytetrafluoroethylene reactor, heated to 150°C, and reacted for 6 hours. After the reaction was completed, the reactor was opened after the temperature dropped to room temperature, and no product was found.

[0122] Comparative Example 4:

[0123] The difference from Example 1 is that only imidazole is added without boric acid during the synthesis of MBON in step 1, which specifically includes:

[0124] 1.73 mmol of zinc nitrate hexahydrate as zinc salt was added to 15 mL of deionized water to obtain solution a; 7.36 mmol of imidazole as organic ligand was added to 15 mL of deionized water to obtain solution b;

[0125] Solution a and solution b were mixed, stirred for 30 minutes, transferred to a polytetrafluoroethylene reactor, heated to 150°C, and reacted for 6 hours. After the reaction was completed, the temperature dropped to room temperature and the reactor was opened, and no product was found.

[0126] Comparative Example 5:

[0127] Different from Example 1, the zinc salt is directly replaced with the copper salt during the synthesis of MBON, and there is no substitution step in step 2, which specifically includes:

[0128] 1.73 mmol of copper nitrate trihydrate and 22.5 mmol of boric acid were added to 15 mL of deionized water to obtain solution a; 7.36 mmol of imidazole as an organic ligand was added to 15 mL of deionized water to obtain solution b;

[0129] Solution a and solution b were mixed, stirred for 30 min, transferred to a polytetrafluoroethylene reactor, heated to 150 °C, and reacted for 6 h. After the reaction was completed, the temperature dropped to room temperature, the reactor was opened, washed with anhydrous ethanol three times, and dried at 80 °C for 12 h to obtain a blue powder.

[0130] Application Example 1

[0131] The novel nano-flower-shaped boron-containing three-dimensional metal-organic framework material prepared in the examples and comparative examples is used for the electric hydrogenation reaction of furfural to prepare furfuryl alcohol, comprising the following steps:

[0132] Step 1: First, 0.005 g of the catalytic material prepared in the examples and comparative examples was added to a mixed solution of 750 μL of ethanol, 200 μL of deionized water, and 50 μL of perfluorosulfonic acid resin (Nafion, 5 wt.%), followed by ultrasonic treatment for 30 min to obtain a uniformly dispersed solution; then, 200 μL of the dispersion was transferred to a spray gun and evenly sprayed on a 2 cm × 1 cm gas diffusion carbon paper, and dried to obtain a catalytic material;

[0133] In step 2, furfural electrocatalytic hydrogenation was performed at room temperature using a standard three-electrode H-type electrolytic cell separated by a Nafion 117 membrane. The prepared catalyst electrode served as the working electrode, a platinum sheet served as the counter electrode, a mercury / mercuric oxide (Hg / HgO) electrode served as the reference electrode, and the electrolyte was a 1 M KOH solution. Furfural electrocatalytic hydrogenation was performed using a Chenhua electrochemical workstation (CHI760e) at a constant potential setting, with a reaction voltage of -0.15 to -0.4 V vs. RHE, and a reaction time of 4 h.

[0134] After the reaction, the reaction solution was taken out and the conversion rate of the reactants and the selectivity of the products were evaluated using liquid chromatography (Hitachi, Primaide). The performance results of furfural hydrogenation to furfuryl alcohol were as follows: Figure 6 As shown in the figure, hydrogenation results show that the novel nanoflower-shaped boron-containing copper-based three-dimensional metal-organic nanosheet catalyst prepared by this invention exhibits a furfuryl alcohol selectivity exceeding 90% under reaction conditions of -0.15 V vs. RHE, but the furfural conversion (45%) and furfuryl alcohol Faradaic efficiency (52%) are relatively low. At -0.30 V vs. RHE, the furfural conversion is 93.9%, and the furfural conversion and furfuryl alcohol selectivity exceed 98%. This demonstrates that potential has a significant impact on furfural conversion and furfuryl alcohol selectivity.

[0135] This new nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework catalytic material also has excellent cycle stability. Figure 7 The results showed that the material still maintained good furfural hydrogenation activity after five cycles, indicating that the material has good industrial application prospects in furfural hydrogenation reactions.

[0136] Experimental results and performance analysis

[0137] The novel nanoflower-shaped boron-containing copper-based three-dimensional metal organic framework catalytic material prepared in the example and the catalytic material prepared in the comparative example were used in the furfural hydrogenation reaction, and the reaction activities of the different catalytic materials were investigated, as shown in Table 1.

[0138] Table 1 Comparison of furfural hydrogenation performance of catalytic materials prepared in Examples and Comparative Examples

[0139]

[0140] Comparison of the hydrogenation results above demonstrates that the nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework catalytic material prepared by the present invention exhibits strong reactivity, far exceeding that of the catalyst used in the comparative example. The novel nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework catalytic material prepared by the present invention possesses abundant active sites and excellent stability. The edges of the nanosheets expose numerous boron-oxygen sites. The strong interaction between boron and copper sites facilitates the exposure of catalytically active sites, promoting the adsorption and activation of reactant molecules at these sites, thereby significantly enhancing the catalyst's catalytic performance.

[0141] Application Example 2

[0142] The catalytic materials prepared in the examples and comparative examples are used for carbon dioxide electroreduction, comprising the following steps:

[0143] The electrocatalytic reaction of carbon dioxide was carried out at room temperature using a standard three-electrode flow-type electrolysis cell separated by a Nafion 117 membrane. The prepared catalyst electrode served as the working electrode, a platinum wire as the counter electrode, and a mercury / mercuric oxide (Hg / HgO) electrode as the reference electrode. The electrolyte was a 1 M KOH solution, and the carbon dioxide flow rate was 30 mL / min. A Chenhua electrochemical workstation (CHI 760e) was used to set the constant potential method for the electrolytic hydrogenation of carbon dioxide, with a reaction voltage of -0.8 to -1.5 V vs. RHE.

[0144] During electrocatalysis, the applied voltage and the properties of the catalyst can synergistically regulate the selective distribution of products. The CO2RR process is a complex chemical reaction. During electrocatalytic CO2 reduction, the main products of two-electron reduction include formic acid and carbon monoxide (CO). Multi-electron reduction products include formaldehyde, methanol, and methane. Simultaneously, when a sufficiently negative overpotential is applied to the electrode, C2 products such as ethylene, acetaldehyde, and ethanol can be generated.

[0145] The selectivity and Faradaic efficiency of the reactants were evaluated using an online gas chromatograph (Shimadzu, Japan). It can be seen that the novel nanoflower-shaped boron-containing copper-based three-dimensional metal-organic framework catalytic material prepared by this invention exhibits excellent electrocatalytic performance and high catalytic activity for carbon dioxide conversion.

[0146] The catalytic material prepared in Example 1 was used for electrocatalytic carbon dioxide reduction reaction, and the reaction activity of the catalytic material at different potentials was investigated, as shown in Table 2 and Figure 8As shown. When the reaction voltage is between -0.8 and -1.5 V vs. RHE, the selectivity for ethylene is greater than 38%, preferably between 38% and 80%. When the reaction voltage is between -1.2 and -1.4 V vs. RHE, the selectivity for ethylene is greater than 64%, preferably between 64% and 80%, and the Faradaic efficiency for ethylene is greater than 58%, preferably between 58% and 70%. In particular, when the reaction voltage is -1.3 V vs. RHE, the selectivity for ethylene is 73.4%, and the Faradaic efficiency for ethylene is 65%.

[0147] Table 2 Reaction activity of the catalytic material prepared in Example 1 at different voltages

[0148]

[0149] Faradaic efficiency (FE) of target product x x ) is calculated as:

[0150] Among them, n x is the amount of substance of the target product x (mol), N is the number of electron transfers when generating the target product x (N is 2 when the product is CO, H2 and formate), F is the Faraday constant (96485C mol -1 ), Q is the charge amount (C) that produces x transfer.

[0151] 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. A boron-containing copper-based three-dimensional metal-organic framework material, characterized in that: The boron-containing copper-based three-dimensional metal-organic framework material is a Cu-based MBON material, where MBON stands for metal-borate-organic framework. The Cu-based MBON material has a columnar structure, and imidazole connects graphene-like CuBO layers through Cu-N coordination to form a pillared layered network. The external morphology of the Cu-based MBON material is a three-dimensional nanoflower, which is formed by the assembly of nanosheets. The method for preparing the boron-containing copper-based three-dimensional metal-organic framework material comprises the following steps: (1) Zn-based MBON was prepared by mixing zinc salt, imidazole and boric acid using a hydrothermal method; (2) Using Zn-based MBON as a precursor, copper salt is used to replace the zinc in Zn-based MBON to prepare Cu-based MBON, thus obtaining a boron-containing copper-based three-dimensional metal-organic framework material; In step (1), the molar ratio of zinc salt, boric acid and imidazole is (1-3):(20-25):(7-8); In step (2), the molar ratio of copper salt to Zn-based MBON precursor is (0.06-0.4):0.2; In step (2), the reaction temperature is 10-80°C and the reaction time is 10-30 min.

2. A method for preparing the boron-containing copper-based three-dimensional metal-organic framework material according to claim 1, characterized in that: The following steps are involved: (1) Zn-based MBON was prepared by mixing zinc salt, imidazole and boric acid using a hydrothermal method; (2) Using Zn-based MBON as a precursor, copper salt is used to replace the zinc in Zn-based MBON to prepare Cu-based MBON, thus obtaining a boron-containing copper-based three-dimensional metal-organic framework material; In step (1), in the hydrothermal reaction, the reaction temperature is 120-160°C, the heating rate is 3-10°C / min, and the reaction time is 5-10h; In step (1), the molar ratio of zinc salt, boric acid and imidazole is (1-3):(20-25):(7-8); In step (2), the molar ratio of copper salt to Zn-based MBON precursor is (0.06-0.4):0.2; In step (2), the reaction temperature is 10-80°C and the reaction time is 10-30 min.

3. The preparation method according to claim 2, characterized in that In step (1), the specific preparation steps of Zn-based MBON are: zinc salt and boric acid are dissolved in a solvent to obtain solution a, imidazole is dissolved in a solvent to obtain solution b, solution a and solution b are mixed, hydrothermally reacted, centrifuged, washed, and dried to obtain the product.

4. The preparation method according to claim 3, characterized in that In step (1), the zinc salt is one or more of zinc sulfate, zinc nitrate, zinc acetate and zinc chloride; In step (1), the solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, acetone, formic acid, methanol, ethanol and water.

5. The preparation method according to claim 2, characterized in that In step (2), the copper salt is one or more of copper sulfate, copper nitrate, copper acetate and copper chloride.

6. An application of the boron-containing copper-based three-dimensional metal-organic framework material according to claim 1 or the boron-containing copper-based three-dimensional metal-organic framework material obtained by the preparation method according to any one of claims 2 to 5 in the electrocatalytic hydrogenation of aldehyde biomass derivatives to alcohol biomass derivatives or the electrocatalytic CO2 reduction reaction.

7. A method for electrocatalytic furfural reduction reaction, characterized in that: The boron-containing copper-based three-dimensional metal-organic framework material according to claim 1 or the preparation method according to any one of claims 2 to 5 is used as a catalyst.

8. The method according to claim 7, characterized in that The method specifically comprises: using a three-electrode system, wherein the working electrode comprises a substrate and the boron-containing copper-based three-dimensional metal-organic framework material; the reference electrode is a mercury / mercuric oxide reference electrode; the counter electrode is a platinum sheet electrode, and electrochemical hydrogenation is performed using the reference electrode and the counter electrode; The electrolyte is a KOH solution having a concentration of 0.8 to 1.2 mol / L; the furfural electrocatalytic voltage is -0.15 to -0.4 V vs. RHE; The reaction time is 2-6h.

9. A method for electrocatalytic CO2 reduction reaction, characterized in that: The boron-containing copper-based three-dimensional metal-organic framework material according to claim 1 or the preparation method according to any one of claims 2 to 5 is used as a catalyst.

10. The method according to claim 9, characterized in that The method specifically comprises: using a three-electrode system, wherein the working electrode comprises a substrate and a catalyst material loaded with the nanoflower-shaped boron-containing copper-based three-dimensional metal organic framework compound; the reference electrode is a mercury / mercuric oxide reference electrode; and the counter electrode is a platinum wire electrode, CO2 is introduced, and electrochemical hydrogenation is performed; The electrolyte is a KOH solution having a concentration of 0.8 to 1.2 mol / L; the voltage of CO2 electrocatalysis is -0.8 to -1.5 V vs. RHE.

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