A super-stable CuBi-EGME catalyst for efficient production of ethylene by CO2 electro-reduction and a preparation method and application thereof

Abstract

The present application relates to a kind of ultra-stable CuBi-EGME catalyst for carbon dioxide electro-reduction high-efficiency ethylene production and its preparation method and application.The catalyst is prepared by sodium borohydride one-step co-reduction method, which co-reduces copper precursor and bismuth precursor in ethylene glycol ether to obtain CuBi-EGME electrocatalyst.The catalyst is applied to electrocatalytic reduction of CO2, and can be highly selectively reduced to ethylene in aqueous electrolyte, and the highest ethylene faradic efficiency can reach 77.0%.In addition, the catalyst shows ultra-strong electrochemical stability, can be stably operated for more than 500 hours without reduction reconstruction during electro-reduction, and can be stably stored in normal temperature air environment, with excellent oxidation resistance.On the other hand, the preparation method of the catalyst is simple, and the product prepared in kilogram still maintains high ethylene selectivity, with good industrial amplification application potential.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic conversion technology, specifically relating to an ultra-stable CuBi-EGME catalyst for the efficient electroreduction of carbon dioxide to ethylene in aqueous solution, its preparation method, and its application. Background Technology

[0002] The continuous rise in atmospheric carbon dioxide (CO2) concentration has become an urgent environmental problem, driving extensive research into carbon capture and utilization technologies. Among various technological pathways, electrocatalytic carbon dioxide reduction reaction (CO2RR) driven by renewable electricity stands out as a promising strategy, capable of converting CO2 into valuable chemicals and fuels, thus achieving a closed loop in the carbon cycle.

[0003] Compared to C1 products, C2 compounds such as ethylene (C2H4) have higher economic value and broader industrial application prospects. As one of the most important C2 products, ethylene is the cornerstone of modern chemical industry, with a global annual production exceeding 200 million tons. It is a key raw material for the production of polyethylene, ethylene oxide, and other high-value-added chemicals, and is widely used in plastics, textiles, and advanced materials. Therefore, converting CO2 to ethylene via CO2RR not only achieves the resource utilization of greenhouse gases but also opens up a new pathway for the green synthesis of this key chemical.

[0004] The formation of ethylene involves 12 electron transfer steps and is limited by slow CC-coupling kinetics. Currently, the efficient production of ethylene via CO2 electroreduction still faces technical bottlenecks, necessitating the development of catalysts that can effectively overcome this kinetic limitation. Copper (Cu)-based materials, due to their unique electronic structure and adsorption capacity for intermediates, are considered ideal catalysts for promoting CC-coupling; however, their ethylene selectivity still needs improvement. Studies have shown that Cu in Cu-based catalysts… + Species play a crucial role in improving the catalytic performance of ethylene. Compared to Cu 0 or Cu 2+ Cu + The site can enhance CO adsorption and lower the CC coupling energy barrier, thereby effectively promoting ethylene production.

[0005] Despite Cu + Species favor ethylene production, but under electrochemical reduction conditions, Cu + It is easily reduced to Cu 0 This leads to a significant decrease in catalyst activity. Therefore, maintaining Cu at the operating potential... + Species stability remains a core challenge in this field. To address this challenge, researchers have proposed various methods for stabilizing Cu. + While strategies exist, existing methods still have significant limitations: in terms of catalytic performance, the Cu content in the catalyst...+ The content of Cu in the catalyst is generally low, with ethylene Faraday efficiencies mostly below 70%, and stable operating times generally less than 200 hours, making it difficult to achieve both high selectivity and long-term stability. In terms of preparation processes, commonly used methods such as solvothermal methods and high-temperature calcination are complex and difficult to scale up. Regarding practical applications, the Cu content in the catalyst... + Sensitive to air, its storage and testing usually require strict oxygen-free environments, which further limits its practical applications.

[0006] Therefore, developing a Cu-based catalyst that is simple to synthesize, structurally stable, easy to scalable, and exhibits high selectivity remains a key problem to be solved in this field. It is necessary to provide a simple preparation method to efficiently generate ethylene and achieve excellent Cu... + Stability. In view of this, the present invention is proposed. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides an ultra-stable CuBi-EGME catalyst for the efficient electroreduction of carbon dioxide to ethylene in aqueous solution. The catalyst exhibits excellent electrocatalytic performance in the reduction of CO2 to ethylene, with a maximum ethylene Faradaic efficiency of 77.0%. Simultaneously, the catalyst demonstrates good electrochemical stability, operating stably for over 500 hours during the electroreduction process without reduction and reconstruction; it can also be stably stored in ambient air at room temperature, exhibiting excellent antioxidant properties.

[0008] This invention also provides a method for preparing the above-mentioned ultra-stable CuBi-EGME electrocatalyst for the efficient electrocatalytic reduction of CO2 to ethylene and its application. The preparation method of the catalyst is simple, and the gram-scale preparation of the product still maintains high ethylene selectivity, showing good potential for industrial scale-up applications.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for preparing an ultrastable CuBi-EGME catalyst for efficient ethylene production by CO2 electroreduction includes the following steps: 1) Disperse copper salt and bismuth salt in ethylene glycol ethyl ether (EGME) to form precursor solution A; 2) Disperse sodium borohydride (NaBH4) in deionized water to form solution B; 3) At room temperature, solution B is added dropwise to the precursor solution A. After the precipitate is completely formed, the solid and liquid are separated to obtain the CuBi-EGME catalyst.

[0010] As a preferred technical solution, in step 1), the copper salt is copper nitrate trihydrate (Cu(NO3)2·3H2O), and the bismuth salt is bismuth nitrate pentahydrate (Bi(NO3)3·5H2O).

[0011] Specifically, the molar ratio of the copper salt, bismuth salt, and sodium borohydride can be 38-40:1:100. More preferably, in the precursor solution A, the amount of copper salt added is 1.17 mmol, the amount of bismuth salt added is 0.03 mmol, and the amount of EGME used is 20±10 mL.

[0012] Furthermore, the preferred molar ratio of the copper salt, bismuth salt, and NaBH4 is 1.17:0.03:3; in solution B, the amount of NaBH4 added is 3 mmol, and the amount of deionized water is 2-4 mL.

[0013] The present invention also provides a CuBi-EGME catalyst prepared by the above preparation method.

[0014] The present invention further provides the application of the CuBi-EGME catalyst in the efficient electroreduction of CO2 to produce ethylene.

[0015] Furthermore, the application includes: dispersing the CuBi-EGME catalyst in a volatile solvent, adding Nafion solution as a binder, ultrasonically dispersing to obtain an electrode dispersion; coating the electrode dispersion onto carbon paper and drying at room temperature to obtain a working electrode; and performing constant voltage electrolysis in a closed three-electrode system.

[0016] Preferably, the volatile solvent is isopropanol; the volume ratio of the volatile solvent to the Nafion solution is 22-26:1, and the mass concentration of the Nafion solution is 4-6%; the concentration of the CuBi-EGME catalyst in the electrode dispersion is 8-12 mg / mL. -1 .

[0017] More preferably, the three-electrode system uses a saturated calomel electrode as the reference electrode and a platinum mesh electrode as the counter electrode, and performs constant-voltage electrolysis in a 0.3~0.5 M KHCO3 aqueous solution. The voltage of the constant-voltage electrolysis is -0.9 V to -1.4 V (vs. RHE). The electrolytic cell used is an H-type electrolytic cell, with the working electrode and the reference electrode located on the same side, and the counter electrode located on the other side.

[0018] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1) This invention is the first to prepare a CuBi-EGME catalyst via a one-step NaBH4 co-reduction method using CuBi bimetallic salt as a precursor and EGME as a reaction solvent, and then applies it to the electrocatalytic reduction of CO2 for efficient ethylene production. The EGME molecule is rich in hydroxyl and ether bonds, and its application in the preparation of electrocatalytic CO2 reduction catalysts provides a new approach for related fields.

[0019] 2) The catalyst of this invention has excellent electrocatalytic performance in reducing CO2 to ethylene. At a potential of -1.3 V (vs. RHE), the ethylene Faradaic efficiency can reach 77.0%. During 500 h of constant potential electrolysis, the ethylene Faradaic efficiency and current density do not decrease significantly, showing an ultra-stable catalytic structure.

[0020] 3) The catalyst of this invention can be stored stably in air without special protection, exhibiting excellent antioxidant capacity.

[0021] 4) The catalyst of this invention is simple to synthesize. It is prepared by a one-step reduction method and requires no further processing. The gram-scale preparation of the product still maintains high ethylene selectivity and has good potential for industrial scale-up applications. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating the synthesis of the CuBi-EGME catalyst of this invention.

[0023] Figure 2 This is a morphology and elemental distribution diagram of the CuBi-EGME catalyst prepared in Example 1 of this invention; wherein, Figure 2 a is the SEM image. Figure 2 b is the TEM image. Figure 2 c is the HRTEM image. Figure 2 d is the distribution map of EDS elements.

[0024] Figure 3 These are morphological images of the Cu and Bi catalysts prepared in Examples 3 and 4 of this invention; wherein, Figure 3 a and d are SEM images. Figure 3 b and e are TEM images. Figure 3 c and f are HRTEM images.

[0025] Figure 4 These are phase and chemical structure characterization diagrams of the catalysts obtained in Examples 1, 3, and 4 of this invention; wherein, Figure 4 a represents the XRD pattern. Figure 4 b is the XPS full spectrum of CuBi-EGME. Figure 4 c is the Cu 2p XPS spectrum of CuBi-EGME. Figure 4 d is the Bi 4f XPS spectrum of CuBi-EGME. Figure 4 e represents the O 1s XPS spectrum of CuBi-EGME. Figure 4 f is the Cu LMM Auger spectrum of CuBi-EGME. Figure 4 g is the Cu LMM Auger spectrum of Cu. Figure 4 h represents the Bi 4f XPS spectrum of Bi.

[0026] Figure 5 These are CO2 reduction performance graphs of the catalysts obtained in Examples 1, 3, and 4 of this invention; wherein, Figure 5 a is the distribution diagram of CO2 reduction products of Cu sample. Figure 5 b is the distribution diagram of CO2 reduction products of Bi sample. Figure 5 c is the distribution diagram of CO2 reduction products of the CuBi-EGME sample. Figure 5 Comparison of CO2 reduction performance of three samples: Cu, Bi, and CuBi-EGME at a potential of -1.3 V (vs. RHE).

[0027] Figure 6 This is a stability test diagram of the CuBi-EGME catalyst prepared in Example 1 of this invention.

[0028] Figure 7 These are structural comparison diagrams of the CuBi-EGME catalyst prepared in Example 1 of this invention before and after stability testing; wherein, Figure 7 a represents the SEM images before and after the stability test. Figure 7 b shows the XRD patterns before and after the stability test. Figure 7 c represents the XPS spectra before and after the stability test.

[0029] Figure 8 These are morphological and performance characterization diagrams of the CuBi-H2O catalyst prepared in Example 2 of this invention; wherein, Figure 8 a is the SEM image of CuBi-H2O. Figure 8 b is the CO2 reduction performance test graph of CuBi-H2O. Figure 8 c represents the stability test result of CuBi-H2O at a potential of -1.3 V (vs. RHE). Figure 8 d is a comparison of the XRD patterns of CuBi-EGME and CuBi-H2O before and after the stability test.

[0030] Figure 9 These are the infrared spectra of the CuBi-EGME and CuBi-H2O catalysts prepared in Examples 1 and 2 of this invention; wherein, Figure 9 a is 800 ~ 1200 cm -1 band, Figure 9 b is 500 ~ 750 cm-1 band, Figure 9 c is 3100 ~ 3600cm -1 Band.

[0031] Figure 10 These are structural stability test diagrams of the CuBi-EGME and CuBi-H2O catalysts prepared in Examples 1 and 2 of this invention; wherein, Figure 10 a is the cyclic voltammetry curve. Figure 10 b is the quasi-in-situ XRD pattern.

[0032] Figure 11 This is a characterization diagram of the performance and structure of the CuBi-EGME catalyst prepared in Example 1 of this invention after being placed in air without special protection for one year (labeled as CuBi-EGME-L); wherein, Figure 11 a is the distribution diagram of CO2 reduction products. Figure 11 b is the XRD pattern.

[0033] Figure 12 These are physical images and performance diagrams of the gram-scale CuBi-EGME catalyst (labeled CuBi-EGME-S) prepared in Example 5 of this invention; wherein, Figure 12 a is a photograph of the gram-scale prepared product. Figure 12 b is a distribution diagram of CO2 reduction products. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0035] In the following examples, all raw materials used were commercially available products. Ethylene glycol ether (99%) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; copper nitrate trihydrate (AR) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; bismuth nitrate pentahydrate (≥99.0%) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; sodium borohydride (98%) was purchased from Tianjin Fuyu Fine Chemical Co., Ltd.; Nafion solution (5 wt.% perfluorosulfonic acid resin solution, containing 45% water, 48±3% isopropanol and <4% ethanol) was purchased from Suzhou Shengernuo Technology Co., Ltd.; isopropanol (99.5%) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; and carbon paper (HCP020P) was purchased from Shanghai Hesen Electric Co., Ltd.

[0036] Room temperature refers to 25±5℃. Example 1

[0037] Preparation of CuBi-EGME electrocatalysts.

[0038] Preparation method of CuBi-EGME catalyst for efficient ethylene production by catalytic electroreduction of CO2 (synthetic route as follows) Figure 1 (As shown), including the following steps: 1) Weigh 1.17 mmol Cu(NO3)2·3H2O and 0.03 mmol Bi(NO3)3·5H2O and add them to 20 mL EGME. Stir and mix well to form precursor solution A; 2) Weigh 3 mmol of NaBH4 and dissolve it in 2 mL of deionized water to form solution B; 3) Slowly add solution B to precursor solution A, stir for about 10 min until precipitation is complete, filter, and wash three times by centrifugation with a 1:1 mixture of water and ethanol at 8000 rpm to obtain the black solid product CuBi-EGME electrocatalyst. Example 2

[0039] Preparation of CuBi-H2O electrocatalyst.

[0040] The specific experimental procedure is the same as in Example 1, except that in step 1), the solvent EGME is replaced with deionized water to obtain CuBi-H2O electrocatalyst. Example 3

[0041] Preparation of Cu electrocatalysts.

[0042] The specific experimental procedure is the same as in Example 1, except that in step 1), only 1.2 mmol Cu(NO3)2·3H2O is added, and the synthesis solvent is deionized water, to obtain Cu electrocatalyst. Example 4

[0043] Preparation of Bi electrocatalysts.

[0044] The specific experimental procedure is the same as in Example 1, except that in step 1), only 1.2 mmol Bi(NO3)3·5H2O is added, and the synthesis solvent is deionized water, to obtain the Bi electrocatalyst. Example 5

[0045] Preparation of CuBi-EGME-S electrocatalyst.

[0046] The specific experimental procedure is the same as in Example 1, except that in step 1), the amount of copper salt, bismuth salt, EGME, NaBH4 and deionized water added is increased tenfold to obtain CuBi-EGME-S electrocatalyst. Example 6

[0047] Accurately weigh 5 mg of the CuBi-EGME catalyst synthesized in Example 1, disperse it in 480 μL of isopropanol, add 20 μL of Nafion solution, and sonicate for 30 min to obtain a homogeneous electrode dispersion. Take 200 μL of the above electrode dispersion and drop it onto a 0.5 × 1 cm⁻¹ plate. 2 The working electrode is prepared by drying the carbon paper at room temperature. Example 7

[0048] Accurately weigh 5 mg of the CuBi-H2O catalyst synthesized in Example 2, disperse it in 480 μL of isopropanol, add 20 μL of Nafion solution, and sonicate for 30 min to obtain a homogeneous electrode dispersion. Take 200 μL of the above electrode dispersion and drop it onto a 0.5 × 1 cm plate. 2 The working electrode is prepared by drying the carbon paper at room temperature. Example 8

[0049] Accurately weigh 5 mg of the Cu catalyst synthesized in Example 3, disperse it in 480 μL of isopropanol, add 20 μL of Nafion solution, and sonicate for 30 min to obtain a homogeneous electrode dispersion. Take 200 μL of the above electrode dispersion and drop it onto a 0.5 × 1 cm plate. 2 The working electrode is prepared by drying the carbon paper at room temperature. Example 9

[0050] Accurately weigh 5 mg of the Bi catalyst synthesized in Example 4, disperse it in 480 μL of isopropanol, add 20 μL of Nafion solution, and sonicate for 30 min to obtain a homogeneous electrode dispersion. Take 200 μL of the above electrode dispersion and drop it onto a 0.5 × 1 cm plate. 2 The working electrode is prepared by drying the carbon paper at room temperature. Example 10

[0051] Accurately weigh 5 mg of the CuBi-EGME-S catalyst synthesized in Example 5, disperse it in 480 μL of isopropanol, add 20 μL of Nafion solution, and sonicate for 30 min to obtain a homogeneous electrode dispersion. Take 200 μL of the above electrode dispersion and drop it onto a 0.5 × 1 cm⁻¹ plate. 2 The working electrode is prepared by drying the carbon paper at room temperature.

[0052] Application trials. Constant voltage electrolysis was performed in an H-type electrolytic cell containing a 0.4 M KHCO3 aqueous solution using a three-electrode system. Electrodes prepared in Examples 6-10 were used as working electrodes, a saturated calomel electrode (SCE) as a reference electrode, and a platinum mesh electrode as a counter electrode. The working and reference electrodes were placed on the same side, and the counter electrode on the opposite side. Magnetic stirring was applied during electrolysis at a speed of 500 rpm, and the voltage range for constant voltage electrolysis was -0.9 V to -1.4 V (vs. RHE). The selectivity of the catalysts prepared in Examples 1-5 for the catalytic reduction of CO2 to ethylene was tested.

[0053] Figure 2 The images show SEM (a), TEM (b), HRTEM (c), and EDS mapping (d) of the CuBi-EGME catalyst prepared in Example 1 of this invention. Figure 2 a and Figure 2 As can be seen from b, this catalyst is an aggregate of random nanoparticles with an average particle size of approximately 30 nm, which is beneficial for increasing specific surface area, promoting electrolyte mass transfer, and exposing more active sites. Figure 2 c indicates that Cu in CuBi-EGME exists in the form of Cu2O and Cu elemental. Due to the small amount of Bi precursor added, no lattice fringes corresponding to the Bi species were observed in the HRTEM image. Figure 2 The d-axis shows that Cu, Bi, and O elements are uniformly distributed in the sample, indicating that Bi has been successfully introduced and the CuBi-EGME catalyst has been successfully synthesized.

[0054] Figure 3 The images show SEM (a, d), TEM (b, e), and HRTEM (c, f) images of the catalysts prepared in Examples 3 (Cu) and 4 (Bi) of this invention. As can be seen from the images, both samples exhibit an irregular nanoparticle aggregate morphology, and most of the Cu and Bi elements exist in the oxidized state in the obtained samples.

[0055] Figure 4 The XRD (a) and XPS (bh) spectra of the catalysts prepared in Examples 1 (CuBi-EGME), 3 (Cu), and 4 (Bi) of this invention are shown. The XRD results indicate that... Figure 4a) The Cu sample exhibits distinct characteristic diffraction peaks at 36.5° and 61.6°, corresponding to the (111) and (220) crystal planes of Cu2O, respectively. Simultaneously, diffraction peaks of the Cu(111) and Cu(200) crystal planes are observed at 43.4° and 50.4°. The Bi sample shows a main diffraction peak at 27.4° corresponding to the (012) crystal plane of Bi2O3, while weak diffraction peaks at 37.9° and 39.6° correspond to the Bi(014) and Bi(110) crystal planes, respectively. In the XRD pattern of the CuBi-EGME catalyst, the diffraction peaks corresponding to the Cu species are basically consistent with those of the Cu sample, indicating that no Cu-Bi alloy phase has formed in the catalyst, and its phases are mainly composed of elemental Cu, Cu2O, and trace amounts of Bi2O3. Compared with the Cu sample, the diffraction peak intensity of Cu2O in CuBi-EGME is significantly increased, while the diffraction signal of metallic Cu is weakened. XPS analysis results ( Figure 4 The results (bh) indicate that the CuBi-EGME catalyst contains Cu, O, and Bi elements, consistent with the EDS surface scan results. The high-resolution Cu 2p spectrum ( Figure 4 c) at 933.1 eV (Cu 2p 3 / 2 ) and 953.1 eV (Cu 2p 3 / 2 The peak at ) exhibits a typical double peak. After peak fitting, two sub-peaks at 932.3 eV and 933.8 eV are obtained, which are attributed to Cu. + / Cu 0 Species and Cu 2 + Species. High-resolution spectrum of Bi 4f ( Figure 4 In d), 159.2 eV (Bi 4f) 7 / 2 ) and 164.5 eV (Bi 4f 7 / 2 Bi appears at ) 3+ The characteristic double peaks indicate that Bi mainly exists in the form of Bi₂O₃. (O 1s high-resolution spectrum) Figure 4 In (e), the main peak at 530.3 eV corresponds to lattice oxygen in Cu₂O, which is consistent with the XRD results. Cu LMM Auger spectrum ( Figure 4 f) shows that the CuBi-EGME catalyst exhibits characteristic peaks at 573.8 eV and 568.9 eV, which are attributed to Cu, respectively. 2+ and Cu + Species, quantitative analysis showed that Cu + The relative content was 86.3%. For comparison, the Cu sample ( Figure 4 g) Cu + The relative content is 70.9%, Cu 0 The relative content was 14.6%; Bi sample ( Figure 4 h) In addition to Bi 3+In addition to the characteristic peaks, Bi-attributable peaks were detected at lower binding energies. 0 The results indicate that the EGME solvent and the introduction of trace amounts of Bi jointly regulate the valence state distribution of Cu in the catalyst.

[0056] Combination Figures 2 to 4 It can be seen that the CuBi-EGME catalyst prepared in Example 1 has a higher Cu2O content and a corresponding Cu content. + A greater number of active sites promotes the C-C coupling reaction, thereby increasing C-C ratio. 2+ The product formation efficiency. This demonstrates that the introduction of Bi plays a crucial role in regulating the Cu₂O / Cu ratio in the catalyst.

[0057] Figure 5 The distribution of CO2 reduction products of the catalysts prepared in Examples 1 (CuBi-EGME), 3 (Cu), and 4 (Bi) of this invention is shown. The Cu sample exhibits a C2H4 Faradaic efficiency of only 30.9% at -1.3 V (vs. RHE), with the hydrogen evolution reaction (FE) dominating. H2 The efficiency was 51.4%. The Bi sample only produced formic acid; C2H4 was not detected. The main product of the CuBi-EGME catalyst was C2H4. At -1.3 V (vs. RHE), the C2H4 Faradaic efficiency reached 77.0%, which was 2.4 times that of the Cu sample. The ratio of C2 to C1 product Faradaic efficiency (FE) was also high. C2 / FE C1 The increase to 12.8 indicates a significant enhancement in its CC coupling ability.

[0058] Figure 6 This is a potentiostatic stability test graph of the CuBi-EGME catalyst prepared in Example 1 of this invention at a potential of -1.3 V (vs. RHE) for 500 h. During the test, the reduction current density did not decrease significantly, and the C2H4 Faraday efficiency remained above 70%, demonstrating excellent long-term stability.

[0059] Figure 7 The images show the structure and phase characterization of the CuBi-EGME catalyst prepared in Example 1 of this invention before and after stability testing. Figure 7 a is the SEM image. Figure 7 b is the XRD pattern. Figure 7 c is the XPS Cu LMM Auger spectrum. The figure shows that the sample morphology did not change significantly after the stability test. Figure 7 a), Cu2O(111) remains the dominant crystal plane, and its relative content has slightly decreased from 89.4% before the reaction to 84.6%. Figure 7 b), Cu + The relative content is 84.9% ( Figure 7 c), which is basically the same as before the stability test (86.3%), indicating that Cu + The active components remained stable during long-term testing.

[0060] Figure 8 These are SEM images showing the morphology and performance characterization of the CuBi-H2O catalyst prepared in Example 2 of this invention. Figure 8 a) shows that CuBi-H2O particles significantly agglomerate and have poor dispersibility. Electrochemical tests indicate that its C2H4 Faraday efficiency is only 48.7%, far lower than the 77% of CuBi-EGME. Figure 8 b), and it becomes completely inactive in less than 10 hours ( Figure 8 c). XRD analysis showed that after the stability test, the Cu2O phase in CuBi-H2O was completely reduced to metallic Cu ( Figure 8 d), indicating that it is difficult to stably maintain Cu + Price state.

[0061] Figure 9 Infrared spectra of CuBi-EGME and CuBi-H2O prepared in Examples 1 and 2 of this invention are given. Both CuBi-EGME and the EGME control sample show spectra at approximately 1060 cm⁻¹. -1 Asymmetric stretching vibrations (ν) of the COC bond occur at this location. as (COC) peak, and the peak position did not shift significantly. Figure 9 a) indicates that ether bonds are mainly attached to the catalyst surface through physical adsorption. Unlike ether bonds, the vibrational modes of Cu-O and OH bonds show a significant shift: compared to CuBi-H₂O, the stretching vibrations of both Cu-O and OH bonds in CuBi-EGME exhibit a red shift ( Figure 9 (b, c) indicates that the hydroxyl oxygen of EGME reacts with Cu + Coordination occurred; simultaneously, compared to pure EGME, the OH stretching vibration peak in CuBi-EGME showed a blue shift. These results indicate that EGME exhibits a dual interaction mode on the CuBi-EGME surface: ether bonds adhere to the catalyst surface via physical adsorption, while hydroxyl groups interact with Cu... + Active sites form chemical coordination, thereby enhancing Cu + Resistance to reduction and structural stability under electrochemical reduction conditions.

[0062] Figure 10 The structural stability test diagrams of the CuBi-EGME and CuBi-H2O catalysts prepared in Examples 1 and 2 of this invention are given. (The stability test results are presented at 100 mV s⁻¹.) -1At the scan rate, the CV curve of CuBi-H2O shows Cu appearing at approximately 0.45 V (vs. RHE). 0 Oxidized to Cu + The anode peak appears at approximately 0.26 V, where Cu... + Reduced to Cu 0 The cathode peak was observed; while CuBi-EGME did not show a significant redox peak in the same potential range. Figure 10 a). Quasi-in-situ XRD results ( Figure 10 b) Further evidence shows that Cu in CuBi-EGME + The content of Cu in CuBi-H2O remained essentially constant throughout the reaction, while the content of Cu in CuBi-H2O remained relatively constant. + The concentration of Cu decreases continuously as the reaction proceeds. These results confirm that Cu in CuBi-EGME... + It can maintain a stable valence state during the electroreduction of CO2.

[0063] Figure 11 The antioxidant stability of CuBi-EGME prepared in Example 1 of this invention is presented. After the sample was stored in air for one year (labeled CuBi-EGME-L), its CO2 electroreduction performance showed no significant decrease compared with that of the freshly prepared sample. Figure 11 a) XRD analysis showed that the sample still maintained a high proportion of Cu₂O phase, Cu + The content reaches 88.4% ( Figure 11 b). The above results indicate that Cu coordinated by EGME... + It is effectively protected in the atmospheric environment.

[0064] Figure 12 A physical image of the gram-scale CuBi-EGME catalyst (labeled CuBi-EGME-S) prepared in Example 5 of this invention is provided. Figure 12 a) Performance graph. After scaling up the synthesis from the milligram level to the gram level, the resulting catalyst (CuBi-EGME-S) still maintained excellent catalytic activity, with a C2H4 Faradaic efficiency exceeding 74%. Figure 12 (b) indicates that the method has good reproducibility and scalability potential.

[0065] In summary, this invention provides a simple and convenient CuBi-EGME catalyst by one-step co-reduction of copper and bismuth precursors using NaBH4 in EGME solvent. This catalyst exhibits excellent CO2 electroreduction performance for ethylene production, with a C2H4 Faradaic efficiency of 77.0%, and excellent catalytic stability, with minimal changes in morphology and structure after the reaction. Furthermore, the catalyst demonstrates good antioxidant capacity and potential for large-scale preparation, showing promising prospects for industrial application.

[0066] The above are merely preferred embodiments of the present invention, but the present invention is not limited to the specific implementation schemes described above. All equivalent changes and modifications made in accordance with the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims

1. A method for preparing an ultrastable CuBi-EGME catalyst for efficient ethylene production by CO2 electroreduction, characterized in that, Includes the following steps: 1) Disperse copper salt and bismuth salt in ethylene glycol ethyl ether to form precursor solution A; 2) Disperse sodium borohydride in deionized water to form solution B; 3) Add solution B to the precursor solution A, and after precipitation is complete, separate the solid and liquid to obtain the CuBi-EGME catalyst.

2. The preparation method according to claim 1, characterized in that, In step 1), the copper salt is copper nitrate trihydrate and the bismuth salt is bismuth nitrate pentahydrate.

3. The preparation method according to claim 1, characterized in that, The molar ratio of the copper salt, bismuth salt and sodium borohydride is 38-40:1:

100.

4. The CuBi-EGME catalyst is prepared by the preparation method according to any one of claims 1 to 3.

5. The application of the CuBi-EGME catalyst according to claim 4 in the efficient electroreduction of CO2 to produce ethylene.

6. The application according to claim 5, characterized in that, The CuBi-EGME catalyst was dispersed in a volatile solvent, and Nafion solution was added as a binder to obtain an electrode dispersion. The electrode dispersion was coated on carbon paper and dried at room temperature to obtain a working electrode. Constant voltage electrolysis was performed in a closed three-electrode system.

7. The application according to claim 6, characterized in that, The volatile solvent is isopropanol; the volume ratio of the volatile solvent to the Nafion solution is 22-26:1, and the mass concentration of the Nafion solution is 4-6%; the concentration of the CuBi-EGME catalyst in the electrode dispersion is 8-12 mg / mL. -1 .

8. The application according to claim 6, characterized in that, The three-electrode system uses a saturated calomel electrode as the reference electrode and a platinum mesh electrode as the counter electrode, and performs constant voltage electrolysis in a 0.3~0.5 M KHCO3 aqueous solution, wherein the voltage of the constant voltage electrolysis is -0.9 V to -1.4 V.

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