Preparation method and application of electron-rich nest molecular fence skeleton for CuFe nano-alloy inhabitation

Abstract

The invention discloses a preparation method and application of an electron-rich nest molecular fence skeleton for CuFe nano-alloy inhabitation, a special catalyst material takes a molecular fence skeleton with an electron-rich nest as a substrate, Cu ions and Fe ions inhabiting in the electron-rich nest are reduced into the CuFe nano-alloy through calcining in a reducing atmosphere, and the CuFe nano-alloy is used as an electron-rich nest molecular fence skeleton. And the CuFe nano-alloy with ultrahigh reducibility is formed in a molecular fence framework of the electron-rich nest by utilizing the electron supply effect of the electron-rich nest. The preparation process of the catalyst material is simple, high-risk reagents and harsh conditions are avoided, accurate regulation and control of the reaction process can be realized, the repeatability is excellent, the electrochemical catalytic performance of the catalyst material can be optimized and regulated and controlled by adjusting the ratio of Cu to Fe on an electron-rich nest fence molecular skeleton, and meanwhile, the catalyst material can be applied to production of C2H4OH in eCO2RR. The electrocatalyst integrates high activity, high selectivity and high stability, is easy to recycle and can be widely applied to key fields such as environmental governance and energy conversion.

Description

Technical Field

[0001] This invention belongs to the field of catalyst material preparation, and particularly relates to a method for preparing an electron-rich nest molecular fence framework inhabited by CuFe nanoalloys and its application. Background Technology

[0002] The practical application bottleneck of eCO2RR technology lies in how to achieve highly selective and high-yield conversion of the target product while effectively suppressing hydrogen evolution side reactions. The key to solving these problems lies in designing and developing advanced electrocatalysts that combine high activity, high selectivity, and high stability.

[0003] Copper (Cu)-based materials are among the most promising eCO2RR catalysts, with their core advantage lying in their ability to efficiently promote C-C coupling reactions, thereby achieving highly selective formation of C2 products. Electron-rich molecular fence frameworks, due to their numerous and well-defined electron-rich sites, are widely used as supported catalyst carriers. Therefore, electron-rich molecular fence frameworks can precisely modulate the electronic structure and reaction microenvironment of Cu active centers, significantly improving their catalytic efficiency and stability for C2 products, demonstrating enormous application potential. However, the difficult formation and weak adsorption of the key intermediate *CO at Cu sites greatly limits the application of such materials.

[0004] This application utilizes theoretical simulations and preliminary experimental screening to identify the second coordinating metal, Fe, to form a CuFe nanoalloy phase with Cu. The CuFe nanoalloy phase significantly enhances the adsorption of the key intermediate *CO, thereby accumulating more *CO on the catalyst surface and providing more raw materials for the subsequent coupling step to generate C2 products. Furthermore, the rate-limiting step in C2 product production is typically a C-C coupling reaction, and a low C-C coupling step often leads to poor C2 selectivity. Therefore, we introduced the CuFe nanoalloy phase into the electron-rich nest of the electron-rich molecular fence framework. Utilizing the electron-rich effect of the electron-rich nest, the CuFe nanoalloy phase generates high-energy electrons, significantly promoting the activation of the key intermediate *CO and the occurrence of the limiting C-C coupling step, thus achieving high C2H5OH product selectivity.

[0005] Here, we utilize a plasma excitation chamber to excite metals in solution, driving metal ions into the electron-rich nests of the electron-rich molecular fence framework. Through the fixation effect of the electron-rich nests and thermal reduction, we further stabilize the CuFe nanoalloy. Simultaneously, we utilize the electron-supplying effect of the electron-rich nests to induce the CuFe nanoalloy to generate high-energy electrons, optimizing its electronic properties and achieving enhanced electrocatalytic performance of the electron-rich nest molecular fence framework inhabited by the CuFe nanoalloy. The electron-rich nest molecular fence framework inhabited by the CuFe nanoalloy efficiently reduces CO2 to C2H5OH, significantly improving the efficiency of electrical energy utilization. The development of this material plays a crucial role in developing high-performance materials through nanoscale control and in addressing various environmental and energy application challenges caused by massive global CO2 emissions. In the prior art, Chinese patent CN117101666A discloses a copper-zinc alloy catalyst, its preparation method, and its applications. However, this method simultaneously introduces hydrogen and carbon monoxide, both flammable and explosive gases, without any inert gas dilution as a protective measure. Furthermore, the reaction conditions are set at a high pressure of 4 MPa and a high temperature of 300°C, which greatly increases the risk of explosion, and the product conversion efficiency is not outstanding. In contrast, this method only requires the introduction of non-toxic CO2 and reacts at room temperature and pressure. Therefore, the preparation of highly efficient electrocatalysts that can be used under mild conditions is crucial. Summary of the Invention

[0006] To address the aforementioned problems in existing technologies, the present invention aims to provide a method for preparing and applying a CuFe nano-alloy-dominated electron-rich molecular fence framework. This invention offers a well-defined and controllable synthetic route, an environmentally friendly preparation method, and a catalyst with uniform metal particle size and excellent dispersibility. Through the electron-supply effect of the electron-rich nest and the synergistic effect of the CuFe alloy, the catalyst material of this invention exhibits highly efficient *CO generation adsorption and CC coupling promotion. Furthermore, this catalyst possesses excellent long-term stability and recyclability, making it of significant practical application value.

[0007] To control the atomic ratio and stability of Cu and Fe in the catalyst material, this invention employs a plasma excitation method: utilizing the uniform distribution and confinement effect of the electron-rich nests in the electron-rich molecular fence framework itself, uniformly sized and well-proportioned CuFe nanoalloys are obtained within the electron-rich nests of the electron-rich molecular fence framework through plasma excitation; simultaneously, the functional groups are located within the electron-rich nests of the electron-rich molecular fence framework, thus achieving efficient preparation of catalysts for electron-rich molecular fence frameworks inhabited by CuFe nanoalloys.

[0008] In the process of synthesizing catalyst materials, metal ions are excited by a heated plasma exciter to form metal plasma, which is then injected into the electron-rich nests of the electron-rich molecular fence framework by an inert gas. The ratio of Cu to Fe in CuFe nanoalloys is changed by controlling the amount of metal added in the copper and iron salt solutions.

[0009] This CuFe nanoalloy resides in an electron-rich nest molecular fence framework. Using this framework as a substrate, Cu and Fe ions are implanted into the electron-rich nests of the substrate via plasma. The functional groups within these nests induce the formation of CuFe nanoalloys, significantly promoting the activation of the key intermediate *CO and the occurrence of the restricted CC coupling step. The CuFe nanoalloys are then immobilized within the electron-rich nests of the substrate by the confinement effect of the molecular fence framework. The size of the electron-rich nests is on the nanometer scale, as is the doping level of the CuFe alloy; however, the size of the CuFe alloy is smaller than the size of the electron-rich nests. The molar ratio of Cu to Fe is 1:0.5~3, preferably 1:2. The electron-rich nest molecular fence framework is polymerized from a mestri(4-aminophenyl)benzene monomer and a halogenated ligand that substituted H on 1,4-benzenedialdehyde. The substituted halogen group on the benzene ring of substituted 1,4-benzenedialdehyde includes at least one of chlorine (Cl) and bromine (Br). The electrons in the electron-rich nest come from the substituents of H on the benzene ring after the ligand is synthesized into the molecular fence framework. That is, the type of group that serves as the electron source for the electron-rich nest includes chlorine (Cl) or bromine (Br).

[0010] Furthermore, the method for preparing the electron-rich nested molecular fence framework substrate includes the following steps: 1) Add the tris(4-aminophenyl)benzene monomer and ligand to methanol solvent respectively, mix the two solutions, and stir rapidly at room temperature for 1-2 h. The ligand is substituted 1,4-benzenedialdehyde, and the substituent group on the benzene ring of the substituted 1,4-benzenedialdehyde is chlorine (Cl) or bromine (Br). The molar ratio of the ligand to the tris(4-aminophenyl)benzene monomer is 1:1.1-2, and the corresponding volume ratio of methanol is also 1:1.1-2. 2) Add glacial acetic acid to the final mixture obtained in step 1), with a volume ratio of glacial acetic acid to solvent of 1:100~250, shake well, heat to 20~40℃ for reaction, after the heating reaction is completed, cool naturally to room temperature, centrifuge to obtain solid, and then wash and vacuum dry in sequence to obtain the electron-rich nest molecular fence framework substrate.

[0011] Further, in step 1), the ligand is at least one of 2,5-dichloro-1,4-phenylenedialdehyde and 2,5-dibromo-1,4-phenylenedialdehyde, and the molar ratio of monomer to ligand is 1:1.1~2.0, preferably 1:1.5; the solvent is methanol, and the volume ratio of the two is 1:1.1~2, preferably 1:1.5; Further, in step 1), the solvent is methanol, and the volume ratio of methanol to methanol is 1:1.1~2, preferably 1:1.5. Methanol is the solvent in the preparation process of the electron-rich nest molecular fence framework and is the reaction site. Glacial acetic acid is the catalyst for the reaction, playing a role in catalyzing the polymerization of the monomer mesitylene (4-aminophenyl)benzene and ligands into the electron-rich nest molecular fence framework.

[0012] Furthermore, the reaction time for stirring at room temperature in step 1) is 1-2 hours, preferably 1.5 hours; Furthermore, in step 2), the heating temperature is 20~40℃, preferably 30℃, and the heating reaction time is 3~5h, preferably 4h.

[0013] Further, in step 2), the volume ratio of glacial acetic acid to methanol solvent is 1:100~250, preferably 1:150.

[0014] The method for preparing an electron-rich nest molecular fence framework for CuFe nanoalloys includes the following steps: S1: Contains a Cu-Fe salt solution, which is dispensed into an open container and then placed in the plasma excitation chamber of a chemical vapor deposition apparatus. The electron-rich nest molecular fence framework substrate is placed in a quartz vessel, which is then placed in the quartz calcination tube of a closed tube furnace connected to the plasma excitation chamber. S2: Ar is introduced into the plasma excitation chamber and the tube furnace. After the air is purged, the plasma excitation chamber and the tube furnace are heated respectively. The former is continuously heated and excited. The metal ions in the Cu salt solution and Fe salt solution are excited by the plasma exciter and enter the gas atmosphere to form metal plasma. The metal plasma is carried by the introduced argon gas and flows through the electron-rich nest molecular fence framework substrate, so that the metal plasma is injected into the electron-rich nest molecular fence framework substrate. The argon gas should be kept stable during this process. S3: After the device is cooled to room temperature, the electron-rich nest molecular fence framework substrate of copper and iron metal loaded with ions is washed, dried and finally reduced in a reducing atmosphere to obtain the electron-rich nest molecular fence framework inhabited by CuFe nanoalloy.

[0015] Preferably, the electron-rich nest molecular fence framework is in the micrometer range (0.5~1 μm), and the electron-rich nests are in the nanometer range, in order to unify the size of the metal nanoalloys.

[0016] Preferably, with the amount of electron-rich nest molecular fence framework substrate added being 150 mg, the total amount of copper salt and iron salt added is 100-150 mmol, preferably 120-130 mmol; the metal molar ratio of Cu to Fe is 1:0.5~3, preferably 1:2.

[0017] Preferably, argon gas is continuously introduced to drive the metal plasma excited by the plasma excitation chamber into the electron-rich nests of the electron-rich nest molecular fence framework, while removing oxygen in the tube furnace to prevent the formation of oxides. With the amount of the electron-rich nest molecular fence framework substrate added being 150 mg, the argon gas flow rate is 20~50 ml / min, preferably 35 ml / min.

[0018] Preferably, the plasma excitation chamber and the quartz calcination tube are continuously heated. The heating temperature of the plasma excitation chamber is set to 100~300℃, preferably 200℃, and the heating temperature of the quartz calcination tube is 400~500℃, preferably 450℃. The heating time is 3~5h, preferably 4h.

[0019] Preferably, the reduction under a reducing atmosphere is to reduce Cu ions and Fe ions to the metallic state to form an alloy. During the reduction process, the volume fraction of H2 in the H2 / Ar gas stream is 1~5%, preferably 3%, the reduction temperature is 100~300℃, preferably 200℃, and the reduction time is 0.5~2h, preferably 1h.

[0020] This invention also provides the catalytic application of the electron-rich nest molecular fence framework of the CuFe nanoalloy in the production of C2H5OH from eCO2RR.

[0021] The electron-rich nest molecular fence framework of CuFe nanoalloys of the present invention has the following advantages in practical use: Compared to conventional catalysts used in eCO2RR, the electron-rich nest molecular fence framework inhabited by CuFe nanoalloys of this invention not only improves the catalytic performance of *CO generation and adsorption during eCO2RR, but also significantly reduces the energy barrier of the subsequent CC coupling rate-limiting step, thus facilitating the generation of C2H5OH. Furthermore, the electron-rich nest molecular fence framework inhabited by CuFe nanoalloys of this invention exhibits high stability. The metal within the electron-rich nest molecular fence framework is a nanoscale alloy phase, stabilized by the confinement effect of the electron-rich nests within the framework. The functional groups within this framework further induce the generation of high-energy electrons in the CuFe nanoalloy, regulating the electron distribution state and resulting in a material that combines high activity, high selectivity, and high stability.

[0022] 2. Compared with the preparation of traditional nano-alloy catalysts, the preparation process of the electron-rich molecular fence framework inhabited by CuFe nano-alloys in this invention is well-defined, allowing for precise control of the reaction process. The supported CuFe nano-alloys exhibit uniform size and excellent reproducibility. Furthermore, the metal composition ratio in the alloy can be controlled by varying the amount of metal added. Studies have found that the electron-rich molecular fence framework inhabited by CuFe nano-alloys of this invention can catalyze the formation of C2H5OH from eCO2RR with extremely high selectivity and efficiency.

[0023] 3. Because the CuFe nano-alloy of this invention has a simple preparation process, avoids high-risk reagents and harsh conditions, and the electrocatalyst has high activity, high selectivity and high stability, and is easy to recycle, it has great potential in the energy and other fields. Attached Figure Description

[0024] Figure 1 This is a scanning electron microscope image of the electron-rich nest molecular fence framework inhabited by the CuFe nanoalloy prepared in Example 1. Figure 2 This is a scanning electron microscope image of the electron-rich nest molecular fence framework inhabited by the CuFe nanoalloy prepared in Example 2. Detailed Implementation

[0025] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0026] In the following embodiments, the preparation method of the electron-rich nest molecular fence framework is as follows: Tris(4-aminophenyl)benzene monomer and ligand are added to methanol solvent respectively, the two solutions are mixed, and the mixture is stirred at room temperature; then glacial acetic acid is added, and the reaction is heated. After naturally cooling to room temperature, the solid is obtained by centrifugation, then thoroughly washed with tetrahydrofuran and acetone, and dried under vacuum to obtain the electron-rich nest molecular fence framework substrate. In the following embodiments, this electron-rich nest molecular fence framework substrate is used to prepare an electron-rich nest molecular fence framework inhabited by CuFe nanoalloys.

[0027] Of course, those skilled in the art should know that the method for preparing this electron-rich nest molecular fence framework is only a preferred embodiment of the present invention, and the parameters can be adjusted according to actual needs. The electron-rich nest molecular fence framework can also be synthesized using other ligands in the prior art.

[0028] The catalyst of this invention is prepared by a Schiff base reaction to create an electron-rich nest molecular fence framework, which is then used to immobilize CuFe nano-alloys via plasma excitation. The formation of the metal alloy phase is achieved through calcination reduction in a reducing atmosphere. After metal plasma is injected into the electron-rich nests of the electron-rich nest molecular fence framework, a CuFe nano-alloy-dominated electron-rich nest molecular fence framework is formed in a tube furnace under a reducing gas atmosphere. This process, repeated, immobilizes the CuFe nano-alloy within the electron-rich nests of the electron-rich nest molecular fence framework. Specific embodiments are as follows: Example 1: The specific steps for preparing the electron-rich nest molecular fence framework for CuFe nanoalloys are as follows: (1) Add 50 ml of methanol to each of the two beakers as solvents. Add 0.4 mmol of tris(4-aminophenyl)benzene to one beaker and 0.75 mmol of 2,5-dichloro-1,4-benzaldehyde to the other beaker. Then mix the two solutions and stir the mixture at room temperature for 1.5 h. (2) Add 2 ml of glacial acetic acid to the solution obtained in step (1) and heat to 30°C for 4 h; (3) Filter the solution obtained in step (2), wash the obtained solid substance thoroughly with tetrahydrofuran and acetone, and dry it under vacuum at 60°C to obtain an electron-rich nest molecular fence framework. (4) Prepare 100 ml of a mixed methanol solution containing a total molar amount of 120 mmol of copper chloride and ferric chloride, wherein the molar ratio of Cu to Fe is 1:0.5. Dispense the solution into an open container and then add it into the plasma excitation chamber of the plasma vapor deposition apparatus. (5) Weigh 150 mg of electron-rich nest molecular fence framework in a quartz dish and place it in the quartz calcination tube of a closed tube furnace connected to the plasma excitation chamber. (6) Ar is introduced and flows through the plasma excitation chamber and the tube furnace (the same below) in sequence at a flow rate of 30 ml / min. After the air in the excitation chamber and the tube furnace is exhausted, the plasma excitation chamber and the tube furnace are heated respectively. The former is continuously heated and excited. The metal ions in the copper salt and iron salt are excited by the plasma exciter and enter the gas atmosphere to form metal plasma. They are then injected into the electron-rich nest of the electron-rich nest molecular fence framework substrate by the introduced argon gas. The heating temperature of the plasma excitation chamber is set to 200℃ and the heating temperature of the quartz calcination tube is 450℃. The heating and excitation are carried out for 4 hours. During this process, the argon gas is kept stable and the copper chloride and iron chloride are completely volatilized. (7) After cooling to room temperature, thoroughly clean the electron-rich nest molecular fence framework with water and methanol, and dry the obtained electron-rich nest molecular fence framework containing ionic metal to obtain the electron-rich nest molecular fence framework inhabited by CuFe nano ion clusters. (8) The electron-rich nest molecular fence framework of CuFe nano-ion clusters obtained in step (7) is reduced at 200℃ for 1h under H2 / Ar gas flow (H2 volume fraction is 3%) to obtain the electron-rich nest molecular fence framework of CuFe nano-alloys.

[0029] Example 2: Preparation method of electron-rich nest molecular fence framework of CuFe nanoalloy. The method of Example 1 is repeated, except that "2,5-dichloro-1,4-benzaldehyde is replaced with an equal amount of 2,5-dibromo-1,4-benzaldehyde in step (1)", and the other conditions remain unchanged. Finally, the electron-rich nest molecular fence framework of CuFe nanoalloy is obtained.

[0030] Example 3: The preparation method of the electron-rich nest molecular fence framework of CuFe nanoalloy is the same as that of Example 1, except that in step (4), the total molar amount of copper chloride and iron chloride remains unchanged, and the molar ratio of Cu and Fe is adjusted to 1:1. The other conditions remain unchanged, and finally the electron-rich nest molecular fence framework of CuFe nanoalloy is obtained.

[0031] Example 4: The preparation method of the electron-rich nest molecular fence framework of CuFe nanoalloy is the same as that of Example 2, except that in step (4), the total molar amount of copper chloride and ferric chloride remains unchanged, and the molar ratio of Cu and Fe is adjusted to 1:1. The other conditions remain unchanged, and finally the electron-rich nest molecular fence framework of CuFe nanoalloy is obtained.

[0032] Example 5: The preparation method of the electron-rich nest molecular fence framework of CuFe nanoalloy is the same as that of Example 1, except that in step (4), the total molar amount of copper chloride and ferric chloride remains unchanged, and the molar ratio of Cu to Fe is adjusted to 1:2. The other conditions remain unchanged, and finally the electron-rich nest molecular fence framework of CuFe nanoalloy is obtained.

[0033] Example 6: The preparation method of the electron-rich nest molecular fence framework of CuFe nanoalloy is the same as that of Example 2, except that in step (4), the total molar amount of copper chloride and iron chloride remains unchanged, and the molar ratio of Cu to Fe is adjusted to 1:2. The other conditions remain unchanged, and finally the electron-rich nest molecular fence framework of CuFe nanoalloy is obtained.

[0034] Example 7: The preparation method of the electron-rich nest molecular fence framework of CuFe nanoalloy is the same as that of Example 1, except that in step (4), the total molar amount of copper chloride and ferric chloride remains unchanged, and the molar ratio of Cu to Fe is adjusted to 1:3. The other conditions remain unchanged, and finally the electron-rich nest molecular fence framework of CuFe nanoalloy is obtained.

[0035] Example 8: The preparation method of the electron-rich nest molecular fence framework of CuFe nanoalloy is the same as that of Example 2, except that in step (4), the total molar amount of copper chloride and ferric chloride remains unchanged, and the molar ratio of Cu to Fe is adjusted to 1:3. The other conditions remain unchanged, and finally the electron-rich nest molecular fence framework of CuFe nanoalloy is obtained.

[0036] Scanning electron microscopy (SEM) images of the electron-rich nest molecular fence framework inhabited by the CuFe nano-ion clusters prepared in Examples 1 and 2 are shown below. Figure 1 and Figure 2 As shown, the molecular fence frameworks of electron-rich nests composed of different ligands do not differ significantly in appearance, and the ligands mainly affect the electron abundance of electron-rich nests.

[0037] Comparative Example 1: The preparation method of the material in Comparative Example 1 is the same as that in Example 1, except that "2,5-dichloro-1,4-benzaldehyde is replaced with an equal molar amount of 1,4-benzaldehyde in step (1)," and the other steps remain unchanged.

[0038] Comparative Example 2: In this comparative example, only step (1) of Example 3 was changed to the following step during preparation, while the other steps remained unchanged: (1) Add 50 ml of methanol to two beakers as solvents. Add 0.4 mmol of tris(4-aminophenyl)benzene to one beaker and 0.75 mmol of 1,4-benzaldehyde to the other beaker. Then mix the two solutions and stir at room temperature for 1.5 h. Comparative Example 3: In this comparative example, only step (1) of Example 5 was changed to the following step during preparation, while the other steps remained unchanged: (1) Add 50 ml of methanol to two beakers as solvents. Add 0.4 mmol of tris(4-aminophenyl)benzene to one beaker and 0.75 mmol of 1,4-benzaldehyde to the other beaker. Then mix the two solutions and stir at room temperature for 1.5 h.

[0039] Application Example 1: Catalyst Performance Evaluation Using the electron-rich nest molecular fence framework of CuFe nanoalloys obtained in Examples 1-8 and the molecular fence framework of CuFe nanoalloys obtained in Comparative Examples 1-3 as catalysts, the electrochemical reduction reaction of CO2 to generate C2H5OH was tested.

[0040] The experimental conditions were as follows: 5 mg of catalyst was weighed and added to 270 μL of methanol, followed by 30 μL of Nafion. The mixture was sonicated for 30 min to obtain a uniformly dispersed catalyst-like ink. 150 μL of the above-mentioned ink-like ink was sprayed onto the hydrophilic side of a 1 cm × 2 cm hydrophobic carbon paper to obtain the cathode electrode. The anode was a 1 cm × 2 cm carbon paper. The anode and cathode chambers were separated by an ion exchange membrane. The hydrophilic side of the cathode electrode faced the ion exchange membrane, dividing the cathode electrode chamber into two spaces, denoted as the gas-phase hydrophobic space and the liquid-phase hydrophilic space, with the liquid-phase hydrophilic space closer to the ion exchange membrane.

[0041] CO2 gas was continuously introduced into the hydrophobic gas phase space of the cathode chamber at a flow rate of 10 ml / min. The hydrophilic liquid phase space of the cathode chamber and the anode chamber contained electrolytes, which were saturated with CO2-adsorbed 1.0 M potassium bicarbonate aqueous solutions. eCO2RR was tested on an electrochemical workstation at a voltage of -0.7 to -1.1 V. During the reaction, the electrolyte was circulated by a peristaltic pump. The yield of CO2 reduction products was monitored online using GC-MS, and the FE was calculated based on the C2H5OH yield. C2H5OH Calculate the potentials used in the experiment, replacing all potentials with the standard hydrogen electrode (RHE): E(RHE) = E(Ag / AgCl) + (0.21 + 0.059pH).

[0042] The electron-rich nest molecular fence frameworks of CuFe nanoalloys prepared in different embodiments were subjected to CO2 reduction reactions at different test voltages on an electrochemical workstation for 2 h, and the tail gas monitoring results are shown in Tables 1 and 4. Table 1 shows that the electron-rich nest molecular fence frameworks of CuFe nanoalloys prepared in Examples 1-8 all exhibit ethanol selectivity at voltages of -0.7, -0.8V, -0.9V, -1.0V, and -1.1V, meaning the ethanol Faradaic efficiency is not zero. Among these, all examples exhibit the highest ethylene Faradaic efficiency at -1.0V.

[0043] In Example 5, the ligand was 2,5-dichloro-1,4-phenylenedialdehyde, and the Cu-Fe nanoalloy synthesized in a 1:2 ratio exhibited the highest ethanol Faradaic efficiency at -1.0 V. After 2 h of reaction, the Faradaic efficiency at -1.0 V was 79.4%, and the reaction current reached 202.3 mA / cm². -2 This demonstrates that the electron-rich nest molecular fence framework inhabited by the synthesized CuFe nanoalloys possesses excellent catalytic activity.

[0044] Comparing the preparation processes of Examples 5 and 6, when the Cu and Fe addition ratios were consistent (i.e., the alloy nanoparticle composition was the same), but the ligands were different, the electron-rich nest molecular fence framework synthesized using 2,5-dichloro-1,4-phenylenedialdehyde as the ligand significantly improved the performance of CuFe nanoalloys in generating high-energy electrons compared to 2,5-dibromo-1,4-phenylenedialdehyde. The electron-rich nest molecular fence framework of the synthesized CuFe nanoalloy exhibited higher catalytic efficiency for the eCO2RR to C2H5OH conversion. Comparing the preparation processes of Examples 1, 3, 5, and 7, with a fixed ligand, increasing the Cu:Fe addition ratio from 1:0.5 to 1:1, then to 1:2, and finally to 1:3 resulted in the catalytic efficiency of the electron-rich nest molecular fence framework of the synthesized CuFe nanoalloy for the eCO2RR to C2H5OH conversion first increasing and then decreasing. Similarly, the same conclusions can be drawn from comparing Examples 2, 4, 6, and 8. Therefore, the electron-rich nest molecular fence framework inhabited by the CuFe nanoalloy of this invention exhibits the best catalytic efficiency for the eCO2RR to C2H5OH conversion when the ligand is 2,5-dichloro-1,4-phenylenedialdehyde, and the optimal effect is achieved when the molar ratio of Cu to Fe is 1:2. This indicates that the electron-rich nest molecular fence framework synthesized from 2,5-dichloro-1,4-phenylenedialdehyde can better induce and regulate the generation of more high-energy electrons in the 1:2 ratio CuFe alloy, thus accelerating the entire reduction reaction process. The electron-rich nest molecular fence framework inhabited by the CuFe nanoalloy of this invention enables highly efficient and directional eCO2RR to C2H5OH conversion.

[0045] The experimental results of the control examples are shown in Tables 2 and 3. Compared with Examples 4, 5 and 6, the molecular fence framework of CuFe nanoalloys prepared with electron-rich nests is much less efficient in catalyzing the generation of C2H5OH from eCO2RR than the molecular fence framework of CuFe nanoalloys of the present invention.

[0046] Table 1. Electron-rich nest molecular fence framework of CuFe nanoalloys prepared in different embodiments catalyzes eCO2 reduction reaction for 2 h. C2H5OH (%) .

[0047] Table 2. FE content of materials prepared from different control examples during the catalytic reduction of eCO2 for 2 h. C2H5OH (%) .

[0048] Table 3. Current density (mA / cm²) of materials prepared from different control examples during the catalytic electrochemical reduction reaction of eCO₂ for 2 h. -2 ) .

[0049] Table 4. Current density (mA / cm²) of CuFe nanoalloys prepared in different embodiments catalyzing the eCO₂ reduction reaction for 2 h. -2 ) .

[0050] Example 5 demonstrates that the current density and FE can be maintained for over 20 hours during actual testing. C2H5OH Stable. Furthermore, we conducted multiple repeat experiments; the catalyst electrode sheet in Example 5 could be used at least three times for 20 hours, with the current density consistent with FE. C2H5OH The electrocatalytic activity of the electrode sheet should not decrease significantly and should be maintained at least 60% of that of the fresh catalyst electrode.

[0051] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. For example, although one of the raw materials used in the preparation process in the above embodiments is mestri(4-aminophenyl)benzene, it does not mean that mestri(4-aminophenyl)benzene must be used to synthesize the material. As long as a carbon-based material containing three amino groups can be selected to react and generate an electron-rich molecular fence framework, the excellent effects of the present invention can be achieved. For another example, the above embodiments only list the case where the Cu and Fe addition ratio is 1:0.5~2, but through experimentation, adjustments can be made near the optimal conditions within this range, such as a Cu and Fe addition ratio of 1:1.8, which can also achieve the technical effects of the present invention. Furthermore, although the reducing gas used in the above embodiments reduces Cu and Fe ions, it does not mean that only a reducing gas can achieve the effects of the present invention. Other reduction methods can be used to achieve the reduction effect of metal ions on the electron-rich molecular fence framework, and the effects of the present invention can also be achieved.

[0052] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.

Claims

1. A CuFe nanoalloy-based electron-rich nest molecular fence framework, characterized in that, Using a molecular fence framework with electron-rich nests as a substrate, Cu and Fe ions residing in the electron-rich nests are reduced to CuFe nanoalloys by calcination in a reducing atmosphere. By utilizing the electron supply effect of the electron-rich nests, CuFe nanoalloys with ultra-high reducibility are formed within the electron-rich nest molecular fence framework.

2. The electron-rich nest molecular fence framework for CuFe nanoalloy habitat as described in claim 1, characterized in that, The CuFe alloy is doped at the nanomolecular level, and the molar ratio of Cu to Fe is 1:0.5~2, preferably 1:1~1.

5. The electron-rich nest molecular fence framework is polymerized from a mestri(4-aminophenyl)benzene monomer and a ligand-substituted halogen group on the benzene ring of 1,4-benzenedialdehyde. The substituted halogen group on the benzene ring of 1,4-benzenedialdehyde includes at least one of Cl and Br. The electrons in the electron-rich nest come from the substituent group of H on the benzene ring after the ligand is synthesized into the molecular fence framework. That is, the type of group that serves as the electron source of the electron-rich nest includes at least one of Cl and Br.

3. The electron-rich nest molecular fence framework for CuFe nanoalloy habitat as described in claim 1, characterized in that, The method for preparing the molecular fence framework substrate with electron-rich nests includes the following steps: 1) Prepare monomer and ligand solutions. Mix the two solutions and stir rapidly at room temperature for 1-2 hours. The monomer is mestris(4-aminophenyl)benzene, and the ligand is substituted 1,4-benzenedialdehyde. The substituent group on the benzene ring of the substituted 1,4-benzenedialdehyde is at least one of Cl and Br. The molar ratio of the ligand to the mestris(4-aminophenyl)benzene monomer is 1:1.1-2. 2) Add glacial acetic acid to the final mixture obtained in step 1), the final volume fraction of glacial acetic acid in the mixture is 1~4%, shake well, and react at a temperature of 20~40℃ for 2-6 hours. After the heating reaction is completed, let it cool naturally to room temperature, centrifuge to obtain a solid, and then wash and vacuum dry it to obtain the electron-rich nest molecular fence framework substrate.

4. The electron-rich nest molecular fence framework inhabited by CuFe nanoalloys as described in claim 3, characterized in that, In step 1), the ligand includes at least one of 2,5-dichloro-1,4-phenylenedialdehyde and 2,5-dibromo-1,4-phenylenedialdehyde, and the molar ratio of monomer to ligand is 1:1.5-2.0, preferably 1:1.7-1.9; in the system after mixing the two solutions in step 1), the total concentration of monomer and ligand is 5-30 mmol / L, preferably 10-15 mmol / L.

5. The electron-rich nest molecular fence framework of CuFe nanoalloy as described in claim 3, characterized in that, In step 2), the reaction temperature is 30±5℃ and the reaction time is 3~5h, preferably 4h; In step 2), the final volume fraction of glacial acetic acid in the mixture is 2-3%.

6. The method for preparing an electron-rich nest molecular fence framework for CuFe nanoalloys as described in claim 1, characterized in that, Includes the following steps: S1: Contains a Cu-Fe salt solution, which is dispensed into an open container and then placed in the plasma excitation chamber of a chemical vapor deposition apparatus. The electron-rich nest molecular fence framework substrate is placed in a quartz vessel, which is then placed in the quartz calcination tube of a closed tube furnace connected to the plasma excitation chamber. S2: Ar is introduced into the plasma excitation chamber and the tube furnace. After the air is purged, the plasma excitation chamber and the tube furnace are heated respectively. The former is continuously heated and excited. The metal ions in the Cu salt solution and Fe salt solution are excited by the plasma exciter and enter the gas atmosphere to form metal plasma. The metal plasma is carried by the introduced argon gas and flows through the electron-rich nest molecular fence framework substrate, so that the metal plasma is injected into the electron-rich nest molecular fence framework substrate. The argon gas should be kept stable during this process. S3: After the device is cooled to room temperature, the electron-rich nest molecular fence framework substrate of copper and iron metal loaded with ions is washed, dried and finally reduced in a reducing atmosphere to obtain the electron-rich nest molecular fence framework inhabited by CuFe nanoalloy.

7. The method for preparing an electron-rich nest molecular fence framework for CuFe nanoalloys as described in claim 6, characterized in that, With the addition amount of the electron-rich nest molecular fence framework substrate being 150 mg, the total addition amount of copper salt and iron salt is 100-150 mmol, preferably 120-130 mmol; the metal molar ratio of Cu to Fe is 1:0.5~3, preferably 1:

2.

8. The method for preparing an electron-rich nest molecular fence framework for CuFe nanoalloys as described in claim 6, characterized in that, The plasma excitation chamber and the quartz calcination tube are continuously heated. The heating temperature of the plasma excitation chamber is set to 150~300℃, preferably 200℃, and the heating temperature of the quartz calcination tube is 400~500℃, preferably 450℃. The heating time is 3~5h, preferably 4h.

9. The method for preparing an electron-rich nest molecular fence framework for CuFe nanoalloys as described in claim 6, characterized in that, The reducing atmosphere is an H2 / Ar gas flow, wherein the volume fraction of H2 is 1-5%, preferably 3%, the reducing temperature is 100-300℃, preferably 200℃, and the reducing time is 0.5-2h, preferably 1h.

10. The application of the electron-rich nest molecular fence framework of CuFe nanoalloy as described in any one of claims 1 to 5 in the electrocatalytic reduction of CO2 to C2H5OH.

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