Preparation method of CuSb-based flow-through type gas diffusion electrode for effective electrochemical reduction of CO2

Abstract

The invention discloses a preparation method of a CuSb-based flow-through type gas diffusion electrode for effective electrochemical reduction of CO2, and belongs to the field of electrochemical CO2 reduction. The present invention can potentially solve the problem of insufficient mass transfer of CO2 by flow-through gas diffusion electrodes (FTGDEs). According to the method, antimony and copper (Cu) are finely regulated and controlled, and valuable products are generated through electrochemical CO2 reduction. In addition to electrochemical CO2 reduction, the CuSb flow-through gas diffusion electrodes (FTGDEs) also have significant advantages in the fields of wastewater treatment, fuel cells, metal recovery, green chemistry, battery systems, air purification and the like.

Description

Technical Field

[0001] The invention belongs to the field of electrochemical CO2 reduction, and in particular, relates to a method for preparing a CuSb-based flow-through gas diffusion electrode for effective electrochemical reduction of CO2. Background Art

[0002] Electrochemical CO2 reduction is an emerging and attractive route to sustainably produce valuable chemicals and fuels, contributing to the closing of the carbon cycle. In recent years, much attention has been devoted to developing advanced materials and optimizing electrocatalytic operation to improve the effectiveness of this technology. Cost-effective, active, and stable electrodes are essential to achieve selectivity and higher reaction rates.

[0003] The commercial scale utilization of this technology is limited by the inability to achieve higher reaction rates due to insufficient CO2 mass transfer in the planar electrode (<100 mA / cm 2 ). In addition, insufficient CO2 mass transfer also causes excess hydrogen to react, changing the reaction pathway and adversely affecting product selectivity. The synergistic effect between the properties of Cu and Sb can improve the overall catalytic performance of CuSb flow-through gas diffusion electrodes (FTGDEs).

[0004] Gas diffusion electrodes potentially solve the problem of insufficient mass transfer because they deliver the reactant gases directly to the catalyst surface, ensuring maximum availability of CO2 on the catalyst surface for the reduction reaction.

[0005] In the conventional electroreduction process, the gaseous reactants reach the planar electrode surface from the bulk phase of the electrolyte, and therefore, the reduction reaction is mainly dependent on the concentration of the gaseous reactants. The solubility of CO2 in aqueous solution is quite low, and therefore, higher current densities cannot be achieved through planar electrodes due to the poor mass transfer of CO2 to the electrode surface.

[0006] High-cost monometallic catalysts, including copper (Cu), zinc (Zn), silver (Ag), and gold (Au), suffer from poor activity and selectivity, which impairs the efficiency of electrochemical CO2 reduction. Summary of the invention

[0007] The present invention can potentially solve the problem of insufficient CO2 mass transfer through flow-through gas diffusion electrodes (FTGDEs) because it can directly provide gaseous reactants to the catalyst surface, greatly increasing their concentration and reducing diffusion paths. Therefore, significantly higher reaction rates and process efficiencies can be achieved.

[0008] The present invention finely controls antimony and copper (Cu) to produce valuable products such as CO, formic acid and C2H4 through electrochemical CO2 reduction. This provides an alternative to the use of more expensive metals such as CuAg, CuAu, CuZn and CuPd (206.4mA / cm 2 ,72.82%).

[0009] The CuSb flow-through gas diffusion electrode of the present invention solves the problems commonly encountered by conventional flow-through electrodes and single metal catalysts. Its gaseous reactants are forced to penetrate into the electrode wall, thereby forming turbulence, improving the association between CO2 and active sites on the electrode surface. Therefore, the gaseous reactants can be effectively transferred to the electrolyte layer, thereby improving the formation of the three-phase interface and enhancing the reaction kinetics of electrochemical CO2 reduction.

[0010] While planar gas diffusion electrodes (GDEs) have significantly improved the efficiency of electrochemical conversion systems, they have also introduced various problems. For example, they contain complex components, require special cell arrangements, and are expensive to operate. The use of flow-through gas diffusion electrodes is a potential solution to these problems and is an emerging candidate for achieving higher reaction rates and, in turn, higher current densities. These flow-through GDEs provide a larger surface for the three-phase interface required for reduction reactions. Their unique hollow design and compact diameter mean that more fibers can be added without increasing the size of the overall cell. In addition, their manufacture involves an affordable phase transfer and calcination technique, eliminating the need for large equipment and elaborate preparation methods.

[0011] When using CuSb-based flow-through gas diffusion electrodes for electrochemical CO2 reduction, it not only improves the mass transfer of CO2 to the catalyst surface, but also achieves the selective formation of multi-carbon products (CO, formate, C2H4) due to the synergistic effect of Cu and Sb. Therefore, higher current density and selective formation of different products can be achieved.

[0012] The technical problem to be solved by the present invention is to improve the mass transfer of CO2 to the catalyst surface and to improve its catalytic performance by using an alloy of copper and antimony. In a conventional planar electrode, CO2 must be transported from the electrolyte volume to the catalyst surface. However, in a flow-through gas diffusion electrode (FTGDE), CO2 is supplied to one end thereof and permeates through its porous wall to the electrolyte side. Therefore, a higher concentration of CO2 is available for reduction reactions on the catalyst surface.

[0013] It is crucial for the present invention to realize that the CuSb flow-through gas diffusion electrode has sufficient porosity, which allows CO2 to penetrate into the wall and be used for reduction reaction. In addition, the appropriate mass flow rate is also critical (20ml / min) to maintain sufficient CO2 supply to the catalyst surface.

[0014] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0015] The object of the present invention is to provide a method for preparing a CuSb-based flow-through gas diffusion electrode for effective electrochemical reduction of CO2, characterized in that the preparation method is achieved by the following steps:

[0016] Step 1, adding N-methyl-2-pyrrolidone (NMP) to polyetherimide (PEI) and ultrasonically treating for 2 hours;

[0017] Step 2: then add copper particle powder and antimony, stir magnetically under heating for a certain period of time, stop heating, leave overnight under magnetic stirring, and then vacuumize to remove bubbles to obtain a casting solution;

[0018] Step 3: Then, a tubular hollow structure is obtained by electrospinning, and then kept in deionized water for 24 hours and dried in a natural environment;

[0019] Step 4: calcining, cooling naturally at room temperature, hydrogenating for a certain period of time, and drying at room temperature to obtain copper antimony hollow fibers;

[0020] Step 5: insert a copper Fourier transformer into the copper tube and fix it with conductive glue to establish electrical connection. One end of the copper electrode and the connection between the copper tube and the copper antimony hollow fiber are coated with non-conductive glue and sealed with non-conductive glue to obtain a CuSb-based flow-through gas diffusion electrode.

[0021] It is further defined that the raw materials include 8 wt % polyetherimide, 26 wt % N-methyl-2-pyrrolidone, 65 wt % copper particle powder, and 1 wt % antimony.

[0022] It is further defined that in step 1, the ultrasonic frequency is 20 kHz and the time is 2 hours.

[0023] It is further defined that in step 2, the average particle size of the copper particle powder is 10 μm.

[0024] It is further defined that in step 2, the heating temperature is 60° C., and the magnetic stirring speed is 400 rpm.

[0025] It is further defined that in step three, the process parameters of electrospinning are: 0.5 mL / h, 17 kV-20 kV.

[0026] It is further defined that in step 4, the temperature is increased to 600°C at a rate of 5°C / min, calcined at 600°C for 2 hours, and cooled to room temperature at a rate of 5°C / min.

[0027] Further defined, in step 4, in 5% (volume) H2 (argon balance), the temperature is raised to 500°C at a rate of 5°C / min, hydrogenated at 500°C for 1 hour, and cooled to room temperature at a rate of 5°C / min.

[0028] The present invention uses a flow-through gas diffusion electrode to perform an electrocatalytic process to convert CO2 into valuable C1 and C2 products.

[0029] The present invention utilizes a CuSb flow-through gas diffusion electrode to perform electrochemical CO2 reduction and convert it into valuable products.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention combines a unique electrode structure with an efficient catalytic system to enhance gas diffusion rates, improve their availability on the electrode surface, and increase the selective formation of multi-carbon products. This unique structure and catalytic properties ensure that CuSb achieves optimal performance in different electrochemical reactions.

[0032] In addition to electrochemical CO2 reduction, the CuSb flow-through gas diffusion electrodes (FTGDEs) of the present invention also have significant advantages in the fields of wastewater treatment, fuel cells, metal recovery, green chemistry, battery systems and air purification.

[0033] In order to further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. However, the attached drawings are only provided for reference and illustration and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 : The materials, processes and equipment involved in the fabrication of CuSb FTGDE are described;

[0035] Figure 2 (a): Image of CuSb FTGDE;

[0036] Figure 2 (b): Closed SEM image of tubular FTGDE;

[0037] Figure 2 (c): CO2 inlet of FTGDE;

[0038] Figure 2(dg) Surface images of FTGDE at different magnifications, showing the distribution of CuSb particles (scale bars: b: 1 mm, c: 500 μm, d: 100 μm, e: 20 μm, and f: 100 nm)

[0039] Figure 3 Schematic diagram of electrochemical CO2 reduction using CuSb flow-through gas diffusion electrode DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0041] Electrochemical CO2 reduction: The process of converting CO2 into valuable products using electrochemical principles.

[0042] CO2 mass transfer: the amount of CO2 transferred to the electrode surface for reduction reaction.

[0043] Current density (mA / cm 2 ): An indicator to measure the catalytic activity of the electrode.

[0044] Faradaic efficiency (%): a key indicator reflecting the degree of charge conservation and the selectivity of CO2 reduction.

[0045] Example 1

[0046] Copper powder (99.5%, 500nm) and copper foil (0.1×10mm) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. N-methyl-2-pyrrolidone (>99.5%) was from Shanghai MacLean Biochemical Technology Co., Ltd., and polyetherimide was from Saudi Basic Industries Corporation. KHCO3 was purchased from Sinopharm Chemical Reagent Co., Ltd. Platinum foil (10×10×0.1mm) and Nafion 117 membrane (10×10mm) were purchased from DuPont. Potassium chloride saturated silver / silver chloride electrode was purchased from Tianjin Aida Hengsheng Technology Development Co., Ltd., and carbon paper was purchased locally. All chemicals were used as received without additional treatment. We used 18.2MΩH2O (Master-S30UVF water purification system) to prepare the electrolyte solution.

[0047] In this embodiment, CuSb FTGDE is prepared by a simple phase transformation and calcination process, and the specific steps are as follows:

[0048] First, N-methyl-2-pyrrolidone (NMP, 26 wt%) was added to polyetherimide (PEI, 8 wt%). They were used as phase change solvent and polymer binder, respectively. Their mixture was treated in an ultrasonic cleaner at an ultrasonic frequency of 20 kHz for 2 hours to obtain a uniform solution (Solution A).

[0049] Then, copper particle powder (65 wt %, 10 μm) and antimony (1 wt %, 5.4 g) were added to Solution A.

[0050] After preliminary mixing, heating was stopped at 60°C and the solution was placed under magnetic stirring (400 rpm) overnight. Prolonging the stirring time allows Cu, Sb, NMP and PEI to be fully mixed and balanced, promoting the formation of a stable and well-mixed mixture. The obtained slurry was evacuated (8 mbar) for 6 hours to remove bubbles and obtain a casting solution.

[0051] After the spinning process (0.5 mL / h, 20 kV) was completed, a copper antimony tubular hollow structure was obtained, and the hollow structure was kept in solvent-free water for 24 hours to remove NMP in the obtained electrode.

[0052] After drying at 25°C, the hollow structure was calcined at 600°C for 2 hours in a tubular furnace to remove PEI, induce particle sintering and produce grain boundaries. The hollow fiber was cooled naturally at room temperature.

[0053] The fibers were then converted back to copper antimony by hydrogenation at 500°C for 1 hour in 5% by volume H2 (balance argon). During the calcination and hydrogenation of the hollow fibers, the heating and cooling rates were maintained at 5°C min-1.

[0054] A 4 cm long (outer diameter ≈ 1.4 mm) copper Fourier transformer was inserted into the copper tube and fixed with conductive glue to establish electrical connection. One end of the copper electrode and the connection between the copper tube and the copper hollow fiber were coated with non-conductive glue and sealed with non-conductive glue. The CuSb FTGDE was dried at room temperature for 15 h before further testing (linear sweep voltammetry, cyclic voltammetry).

[0055] Different materials, processes and equipment are used to realize the fabrication of CuSb FTGDE, such as Figure 1 SEM analysis ( Figure 2 bg) show that the surface of CuSb FTGDE presents a well-integrated substrate without particles or spherical particles, indicating that the CuSb particles are completely fused and sintered during the synthesis process to form a self-supporting and strong CuSb FTGDE structure ( Figure 2 a), which helps to enhance mechanical strength and electron transport.

Claims

1. A method for preparing a CuSb-based flow-through gas diffusion electrode for effective electrochemical reduction of CO2, characterized in that: The preparation method is achieved by the following steps: Step 1, adding N-methyl-2-pyrrolidone (NMP) to polyetherimide (PEI) and ultrasonically treating for 2 hours; Step 2: then add copper particle powder and antimony, stir magnetically under heating for a certain period of time, stop heating, leave overnight under magnetic stirring, and then vacuumize to remove bubbles to obtain a casting solution; Step 3: Then, a tubular hollow structure is obtained by electrospinning, and then kept in deionized water for 24 hours and dried in a natural environment; Step 4: calcining, cooling naturally at room temperature, hydrogenating for a certain period of time, and drying at room temperature to obtain copper antimony hollow fibers; Step 5: insert a copper Fourier transformer into the copper tube and fix it with conductive glue to establish electrical connection. One end of the copper electrode and the connection between the copper tube and the copper antimony hollow fiber are coated with non-conductive glue and sealed with non-conductive glue to obtain a CuSb-based flow-through gas diffusion electrode.

2. The preparation method according to claim 1, characterized in that: The raw materials include 8wt% polyetherimide, 26wt% N-methyl-2-pyrrolidone, 65wt% copper particle powder and 1wt% antimony.

3. The preparation method according to claim 1, characterized in that: In step 1, the ultrasonic frequency is 20 kHz.

4. The preparation method according to claim 1, characterized in that: In step 2, the average particle size of the copper particle powder is 10 μm.

5. The preparation method according to claim 1, characterized in that: In step 2, the heating temperature is 60° C. and the magnetic stirring speed is 400 rpm.

6. The preparation method according to claim 1, characterized in that: In step 3, the process parameters of electrospinning are: 0.5 mL / h, 17 kV-20 kV.

7. The preparation method according to claim 1, characterized in that: In step 4, the temperature is raised to 600° C. at a rate of 5° C. / min, calcined at 600° C. for 2 hours, and then cooled to room temperature at a rate of 5° C. / min.

8. The preparation method according to claim 1, characterized in that: In step 4, in a mixture of hydrogen and argon, the temperature is raised to 500° C. at a rate of 5° C. / min, hydrogenated at 500° C. for 1 hour, and then cooled to room temperature at a rate of 5° C. / min; the volume concentration of hydrogen in the mixture is 5%.

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