A method for preparing high performance cu-sn catalysts

Abstract

The application relates to the technical field of electrocatalytic materials, and discloses a method for preparing a high-performance CuSn catalyst, which comprises the following steps: S1: a certain amount of sodium thiosulfate pentahydrate is weighed and dissolved in deionized water to prepare a first solution; S2: a certain amount of tin salt and copper salt are respectively weighed and dissolved in deionized water to prepare a second solution; S3: the first solution and the second solution are uniformly mixed, centrifuged for several times, and vacuum dried to obtain a CuSn pre-catalyst; S4: a certain amount of the CuSn pre-catalyst prepared in S3 is weighed and placed in a mixed solvent, an appropriate amount of 5wt% Nafion solution is added, ultrasonic dispersion is carried out for 30-35 minutes, and catalyst ink is formed; and S5: an appropriate amount of the catalyst ink prepared in S4 is drop-coated on carbon paper, and a high-performance CuSn catalyst is obtained through electrochemical reduction. The technical scheme can make the selectivity of electrocatalytic conversion of carbon dioxide into formic acid higher than 90%, the formic acid generation current density is greater than 1 A / cm ‑2 , and has the advantages of simple process, large-scale production, no pollution, low energy consumption, high efficiency and the like.

Description

Technical Field

[0001] This invention relates to the field of electrocatalytic materials technology, and specifically to a method for preparing a high-performance CuSn catalyst. Background Technology

[0002] Electrocatalytic carbon dioxide reduction technology driven by renewable electricity can not only efficiently remove carbon dioxide, but also cleanly and efficiently synthesize chemical raw materials (such as formic acid, methanol, ethylene, ethanol, etc.). Therefore, this method is undoubtedly a key technology for achieving carbon closed-loop.

[0003] Formic acid, a product of carbon dioxide reduction, has extremely high added value and is widely used in energy, environment, pharmaceuticals, and the rubber industry. CuSn-based catalysts, with their abundant reserves, low cost, and environmental friendliness, are widely used in electrocatalytic carbon dioxide reduction. Due to the moderate adsorption strength of CuSn catalysts for the key intermediate in formic acid formation (*OCHO), they exhibit superior selectivity and activity for formic acid compared to single Sn or Cu catalysts. However, current CuSn catalysts struggle to maintain a formic acid selectivity exceeding 90% when faced with ampere-level current densities. This limitation primarily stems from insufficient specificity for formic acid formation, resulting in a broad rather than highly concentrated product distribution. Furthermore, the lower current density indicates a need to improve catalyst activity, thus limiting the product formation rate and making it difficult to meet the demands of industrial applications for efficient, rapid, and highly specific catalytic processes. Therefore, developing CuSn catalysts that maintain high formic acid selectivity at high current densities is a crucial research direction. Furthermore, and more importantly, existing CuSn catalyst preparation technologies often involve high energy consumption, high pollution, and long processing times. Some preparation methods also require expensive and complex equipment. These problems seriously contradict the original intention of electrochemical carbon dioxide reduction. In addition, there is currently a lack of a method for large-scale preparation of high-performance CuSn catalysts. The above problems seriously hinder the industrial application of electrocatalytic carbon dioxide reduction. Summary of the Invention

[0004] This invention aims to provide a method for preparing a high-performance CuSn catalyst, which enables electrocatalytic conversion of carbon dioxide to formic acid with a selectivity exceeding 90% and a formic acid formation current density greater than 1 A / cm². -2 It also has advantages such as simple process, large-scale production, no pollution, low energy consumption and high efficiency.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing a high-performance CuSn catalyst, comprising the following steps:

[0006] S1: Weigh a certain amount of sodium thiosulfate pentahydrate solid and dissolve it in deionized water to prepare solution No. 1, wherein the molar ratio of sodium thiosulfate pentahydrate to deionized water is 1:(150-200).

[0007] S2: Weigh out a certain amount of tin salt and copper salt respectively, and dissolve them in deionized water to prepare solution No. 2. The molar ratio of the total amount of tin salt and copper salt to deionized water is 1:(20-30).

[0008] S3: Mix the first solution prepared in S1 with the second solution prepared in S2 evenly, stir at room temperature for 1-1.5 h, centrifuge and wash several times, and vacuum dry to obtain CuSn precatalyst;

[0009] S4: Weigh a certain amount of the CuSn precatalyst prepared in S3 and place it in a mixed solvent, while adding an appropriate amount of 5wt% Nafion solution, and ultrasonically disperse for 30-35 minutes to form a uniform catalyst ink.

[0010] S5: Take an appropriate amount of the catalyst ink prepared in S4 and drop it onto hydrophobic carbon paper. After electrochemical reduction, a high-performance CuSn catalyst is obtained.

[0011] Preferably, in S2, the molar ratio of tin salt to copper salt is 1:(0.43-1).

[0012] Preferably, the tin salt in S2 is any one or a combination of stannous chloride and stannous sulfate.

[0013] Preferably, the copper salt in S2 is any one or a combination of copper nitrate, copper chloride, and copper sulfate.

[0014] Preferably, in S3, the vacuum drying temperature is 60-100℃ and the drying time is 2-6h.

[0015] Preferably, in S4, the mixed solvent is a mixture of water and ethanol, wherein the volume ratio of water to ethanol is 1:(1-4).

[0016] Preferably, in S4, the volume ratio of Nafion solution to the total amount of catalyst ink is 1:(20-50).

[0017] Preferably, in S4, the concentration of the precatalyst is 8-10 mg / mL.

[0018] Preferably, in step S5, the loading of the pre-catalyst on the hydrophobic carbon paper is 1.5-2 mg / cm³. 2 .

[0019] Preferably, in S5, the electrochemical reduction conditions are: applying a voltage of -1.0V vs. RHE, and pretreating in a carbon dioxide-saturated KHCO3 solution for 20-30 min to obtain a high-performance CuSn catalyst.

[0020] The reaction mechanism is as follows: Sodium thiosulfate possesses both oxidizing and reducing properties. Its oxidizing property can reduce the reducible tin salt (Sn) in the reaction. 2+ ) oxidized to tetravalent tin (Sn) 4+ Meanwhile, the reducing properties of sodium thiosulfate can neutralize the oxidizing properties of copper salts (Cu). 2+ ) reduced to cuprous (Cu + In the reaction, sodium thiosulfate itself is oxidized and reduced to sulfate and sulfur dioxide. The tetravalent tin and cuprous oxide formed by the redox reaction, in the presence of oxygen, eventually form a sulfur-containing CuSn oxide precipitate. This precipitate is centrifuged and dried to obtain a pre-catalyst powder. The pre-catalyst powder is sprayed onto the electrode, and in the carbon dioxide reduction device, under the action of an applied electric field, the pre-catalyst is reduced to the elemental active catalyst, which exhibits excellent activity and selectivity in the reduction of carbon dioxide to formic acid.

[0021] Compared with existing technologies, the beneficial effects of this technical solution are as follows:

[0022] The high-performance CuSn catalyst prepared by this technical solution enables an electrocatalytic conversion of carbon dioxide to formic acid with a selectivity exceeding 90%, and a formic acid formation current density greater than 1 A / cm². -2 Furthermore, the catalyst preparation process described in this application is simple, requiring no complex or expensive equipment. Its reaction conditions are mild and environmentally friendly, posing no pollution concerns, and its energy consumption is extremely low, meeting the requirements of sustainable development. It boasts high raw material utilization and high material yield, enabling large-scale industrial production (340g of catalyst can be prepared in a single batch, and kilogram-level production is also possible). The prepared catalyst exhibits excellent catalytic selectivity, activity, and stability, reaching the current industry-leading performance level.

[0023] The inventors of this technical solution have verified through multiple experiments that sodium thiosulfate is selected as an oxidant and reducing agent, which can significantly increase the reaction rate of tin salts and copper salts and produce precipitates. In contrast, the inventors use sodium sulfide or thiourea as oxidant and reducing agent, which reacts more slowly with tin salts and copper salts and produces less precipitate.

[0024] This technical solution uses a mixture of water and ethanol as a solvent. On the one hand, the addition of ethanol can increase the wettability of the material and enable more uniform coating. On the other hand, the addition of ethanol can accelerate the drying speed of the coated electrode and save time. Attached Figure Description

[0025] Figure 1 The graph shows the selectivity of S-CuSn-Ⅱ and S-CuSn-Ⅱ' in Examples 1-2 and S-Sn, S-CuSn-Ⅰ, S-CuSn-Ⅲ and S-Cu in Comparative Examples 1-4 for the electrocatalytic reduction of carbon dioxide to formic acid in an H-type electrolytic cell as a function of potential.

[0026] Figure 2 The graph shows the partial current density versus potential variation of S-CuSn-Ⅱ and S-CuSn-Ⅱ' in Examples 1-2 and S-Sn, S-CuSn-Ⅰ, S-CuSn-Ⅲ and S-Cu in Comparative Examples 1-4 for the electrocatalytic reduction of carbon dioxide to formic acid in an H-type electrolytic cell.

[0027] Figure 3 (a) is a graph showing the selectivity of S-CuSn-Ⅱ in Example 1 and S-Sn in Comparative Example 1 for the electrocatalytic reduction of carbon dioxide to formic acid in a flow electrolytic cell and the change with total current density.

[0028] Figure 3 (b) is a graph showing the variation of the partial current density with the total current density for the electrocatalytic reduction of carbon dioxide to formic acid by S-CuSn-II in Example 1 and S-Sn in Comparative Example 1 in a flow electrolytic cell.

[0029] Figure 3 (c) is a long-term operational stability diagram of S-CuSn-Ⅱ in Example 1 of the present invention for electrocatalytic carbon dioxide reduction in a flow electrolyzer;

[0030] Figure 4 (a) is a scanning electron microscope image of S-Cu / SnO2-Ⅱ in Example 1 of the present invention;

[0031] Figure 4 (b) is a scanning electron microscope image of S-Cu / SnO2-Ⅱ' in Example 2 of the present invention;

[0032] Figure 4 (c) is the X-ray diffraction pattern of S-Cu / SnO2-Ⅱ in Example 1 of the present invention;

[0033] Figure 4 (d) is the X-ray diffraction pattern of S-Cu / SnO2-Ⅱ' in Example 1 of the present invention;

[0034] Figure 5 (a) is a transmission electron microscope image of S-CuSn-Ⅱ in Example 1 of the present invention;

[0035] Figure 5 (b) is the X-ray diffraction pattern of S-CuSn-II in Example 1 of the present invention;

[0036] Figure 6 (a) is a single-scale preparation diagram of S-Cu / SnO2-Ⅱ' in Example 2 of the present invention;

[0037] Figure 6 (b) is a graph showing the kilogram-scale preparation results of S-Cu / SnO2-Ⅱ' in Example 2 of the present invention;

[0038] Figure 7 (a) is a scanning electron microscope image of S-SnO2 in Comparative Example 1 of the present invention;

[0039] Figure 7 (b) is a scanning electron microscope image of S-Cu / SnO2-Ⅰ in Comparative Example 2 of the present invention;

[0040] Figure 7 (c) is a scanning electron microscope image of S-Cu / SnO2-Ⅲ in Comparative Example 3 of the present invention;

[0041] Figure 7 (d) is S-CuO in Comparative Example 4 of this invention. x Scanning electron microscope image. Detailed Implementation

[0042] The following detailed description illustrates the specific implementation method:

[0043] Example 1

[0044] A method for preparing a high-performance CuSn catalyst includes the following steps:

[0045] S1: Weigh a certain amount of sodium thiosulfate pentahydrate solid and dissolve it in deionized water, stir evenly, and prepare solution No. 1, wherein the molar ratio of sodium thiosulfate pentahydrate to deionized water is 1:(150-200); in this embodiment, the volume of deionized water is 0.0175L, and the molar ratio of sodium thiosulfate pentahydrate to deionized water is 1:173.

[0046] S2: Weigh out a certain amount of tin salt and copper salt respectively, dissolve them in deionized water, stir evenly, and prepare solution No. 2. Solution No. 2 is a turbid liquid. The molar ratio of the total amount of tin salt and copper salt to deionized water is 1:(20-30), and the molar ratio of tin salt to copper salt is 1:(0.43-1). Tin salt is any one or a combination of stannous chloride and stannous sulfate. Copper salt is any one or a combination of copper nitrate, copper chloride, and copper sulfate. In this embodiment, stannous chloride dihydrate is selected as the tin salt, and copper nitrate trihydrate is selected as the copper salt. The volume of deionized water is 0.005L. The molar ratio of the total amount of stannous chloride dihydrate and copper nitrate trihydrate to deionized water is 1:23, and the molar ratio of stannous chloride dihydrate and copper nitrate trihydrate is 1:0.66.

[0047] S3: Mix the first solution prepared in S1 with the second solution prepared in S2 evenly, stir magnetically at room temperature for 1-1.5 hours, centrifuge and wash several times with deionized water, and then perform vacuum drying at a temperature of 60-100℃ for 2-6 hours to obtain CuSn precatalyst. This precatalyst is named S-Cu / SnO2-Ⅱ. In this embodiment, the mixture is magnetically stirred for 1 hour, centrifuged and washed three times with deionized water, and dried at a temperature of 60℃ for 2 hours. Figure 4 (a) is a scanning electron microscope image of S-Cu / SnO2-Ⅱ. Figure 4 (c) is the X-ray diffraction pattern of S-Cu / SnO2-Ⅱ;

[0048] S4: Weigh a certain amount of the CuSn precatalyst prepared in S3 and place it in a mixed solvent. At the same time, add an appropriate amount of 5wt% Nafion solution and ultrasonically disperse for 30-35 min to form a uniform catalyst ink. The mixed solvent is a mixture of water and ethanol, wherein the volume ratio of water to ethanol is 1:(1-4), the volume ratio of Nafion solution to the total amount of catalyst ink is 1:(20-50), and the concentration of the precatalyst is 8-10 mg / mL. In this example, the volume ratio of water to ethanol is 3:7, the volume ratio of Nafion solution to the total amount of catalyst ink is 1:50, and the concentration of the precatalyst is 8 mg / mL. Ultrasonic dispersion is performed for 30 min.

[0049] S5: Take an appropriate amount of the catalyst ink prepared in S4 and drop it onto hydrophobic carbon paper. Electrochemical reduction yields a high-performance CuSn catalyst, named S-CuSn-II. The loading of the pre-catalyst on the hydrophobic carbon paper is 1.5-2 g / cm³. 2 The electrochemical reduction conditions were as follows: applying a voltage of -1.0 V vs. RHE, and pretreating in a carbon dioxide-saturated KHCO3 solution for 20-30 min to obtain a high-performance CuSn catalyst; in this embodiment, the loading of the pre-catalyst on the hydrophobic carbon paper was 1.6 mg / cm³. 2 Pretreatment for 20 minutes; Figure 5 (a) is a transmission electron microscope image of S-CuSn-II. Figure 5 (b) is the X-ray diffraction pattern of S-CuSn-II.

[0050] Depend on Figure 4 It can be seen from the scanning electron microscope and X-ray diffraction patterns of S-Cu / SnO2-Ⅱ that the morphology of the precatalyst is uniformly sized nanoparticles, and its phase is a complex of SnO2 and CuSn compounds.

[0051] Depend on Figure 5It can be seen that after pretreatment, S-CuSn-Ⅱ is a worm-like nanostructure with a diameter of about 13nm, and its composition is Sn element and Cu6Sn5 alloy.

[0052] To demonstrate the excellent electrocatalytic activity of the CuSn catalyst, experiments were conducted on the electrocatalytic reduction of carbon dioxide. The carbon dioxide electrocatalytic reaction was carried out in an H-type reactor (Grosslink, C007-10 replaceable membrane type) and a flow reactor (Grosslink, gas diffusion electrode electrolyzer).

[0053] During the H-type reactor test: hydrophobic carbon paper (Toray 060-30% hydrophobic, 1*1cm, with a pre-catalyst loading of 1.6mg / cm³) was drop-coated with catalyst ink. 2 The electrode was used as the working electrode, and Ag / AgCl and Pt mesh (1*1cm) were used as the reference and counter electrodes, respectively. The anode and cathode were electrolyzed with 10 mL of carbon dioxide-saturated KHCO3 (0.5 mol / L). Constant potential electrolysis was performed using an electrochemical workstation (Metroën, PGSTAT302N), with each potential lasting 20 min. During electrolysis, carbon dioxide was continuously introduced into the cathode at a rate of 25 mL / min, and the cathode cell was magnetically stirred at 600 rpm.

[0054] During the flow reactor test: a gas diffusion electrode (Toray Industries, Japan, YLS-30T, with a pre-catalyst loading of 1.6 mg / mL and a test area of ​​1 cm²) was used. 2 The electrode was a 2*2*0.2cm iron-nickel foam, which served as the reference electrode and the counter electrode, respectively. The anode and cathode were respectively saturated with 50mL of carbon dioxide-based KHCO3 (1mol / L). A peristaltic pump (Kamoer FO1A) was used to circulate the electrolyte at a rate of 20mL / min. Constant current electrolysis was performed using an electrochemical workstation (Metroën, PGSTAT302N), with each current cycle lasting 3 minutes. During electrolysis, carbon dioxide was continuously introduced into the gas chamber at a rate of 20mL / min.

[0055] The generated gaseous products were determined using an online gas chromatograph (GC-2030, equipped with two FID and one FID detectors, N2 carrier gas, Molecular Sieve-13X column, Porapak-N column, Porapak-Q column, Shimadzu). The generated liquid products were determined using a nuclear magnetic resonance spectrometer (AVANCE NEO 400, water suppression mode, Bruker) with dimethyl sulfoxide as the internal standard. Electrocatalytic test results are as follows: Figure 1 , Figure 2 and Figure 3 As shown.

[0056] Example 2

[0057] Unlike Example 1, the amount of deionized water used in S1 was 3.9 L, and the amount of deionized water used in S2 was 1.1 L. The pre-catalyst obtained in S3 was named S-Cu / SnO2-Ⅱ'. An experiment on the electrocatalytic reduction of carbon dioxide was conducted in an H-type reactor, and the results are as follows... Figure 1 and Figure 2 As shown, Figure 4 (b) is a scanning electron microscope image of S-Cu / SnO2-Ⅱ'. Figure 4 (d) is the X-ray diffraction pattern of S-Cu / SnO2-Ⅱ; Figure 6 (a) is a diagram of a single large-scale preparation of S-Cu / SnO2-Ⅱ'; Figure 6 (b) shows the kilogram-scale preparation results of S-Cu / SnO2-Ⅱ'.

[0058] Depend on Figure 4 As can be seen from the scanning electron microscopy and X-ray diffraction results, S-Cu / SnO2-Ⅱ' and S-Cu / SnO2-Ⅱ exhibit completely identical morphology and phase composition. Meanwhile, from Figure 1 and Figure 2 It can be seen that S-Cu / SnO2-Ⅱ' and S-Cu / SnO2-Ⅱ exhibit similar formic acid selectivity and partial current density in the H cell. These results indicate that the method can maintain its morphology, phase and electrocatalytic performance well in large-scale preparation.

[0059] Depend on Figure 6 It can be seen that by scaling up the experiment in Example 1, 340g of catalyst can be harvested in a single batch. After multiple experiments, the preparation of catalyst at the kilogram level can be easily achieved, for example, the preparation of 4100g of catalyst. Thus, it can be seen that the high-performance CuSn catalyst provided by the present invention can be prepared on a large scale.

[0060] Comparative Example 1

[0061] Unlike Example 1, the molar ratio of stannous chloride dihydrate to copper nitrate trihydrate in S2 is 1:0, and the precatalyst obtained in S3 is named S-SnO2. Figure 7 (a) is a scanning electron microscope image of S-SnO2. The high-performance CuSn catalyst obtained in S5 is named S-Sn. Figure 1 The graph shows the selectivity of S-Sn in electrocatalytic reduction of formic acid by carbon dioxide as a function of potential in an H-type electrolytic cell. Figure 2 The graph shows the variation of the partial current density of S-Sn formic acid with potential in an H-type electrolytic cell. Figure 3 (a) is a selectivity diagram of the electrocatalytic reduction of carbon dioxide to formic acid by S-Sn in a flow electrolyzer; Figure 3(b) is a partial current density diagram of the electrocatalytic reduction of formic acid by S-Sn in a flow electrolyzer. Figure 3 As can be seen, compared with S-Sn, S-CuSn-II in Example 1 exhibited higher formic acid selectivity and partial current density. S-CuSn-II achieved a maximum formic acid selectivity of 92.87% and a maximum formic acid partial current density of 1.03 A / cm². -2 At the same time by Figure 3 (c) It can be seen that S-CuSn-Ⅱ can operate stably for more than 300 hours. The above performance level indicates that S-CuSn-Ⅱ has excellent prospects for industrial application.

[0062] Comparative Example 2

[0063] Unlike Example 1, the molar ratio of stannous chloride dihydrate to copper nitrate trihydrate in S2 was 1:0.25, and the pre-catalyst obtained in S3 was named S-Cu / SnO2-Ⅰ. Figure 7 (b) is a scanning electron microscope image of S-Cu / SnO2-Ⅰ. The high-performance CuSn catalyst obtained in S5 is named S-CuSn-Ⅰ. Figure 1 The graph shows the selectivity of S-CuSn-Ⅰ for the electrocatalytic reduction of carbon dioxide to formic acid in an H-type electrolytic cell as a function of potential. Figure 2 The graph shows the variation of formic acid partial current density with potential in an H-type electrolytic cell.

[0064] Comparative Example 3

[0065] Unlike Example 1, the molar ratio of stannous chloride dihydrate to copper nitrate trihydrate in S2 is 1:1.5, and the pre-catalyst obtained in S3 is named S-Cu / SnO2-Ⅲ; Figure 7 (c) is a scanning electron microscope image of S-Cu / SnO2-Ⅲ. The high-performance CuSn catalyst obtained in S5 is named S-CuSn-Ⅲ. Figure 1 The graph shows the selectivity of S-CuSn-Ⅲ for the electrocatalytic reduction of carbon dioxide to formic acid in an H-type electrolytic cell as a function of potential. Figure 2 The graph shows the variation of formic acid partial current density with potential in an H-type electrolytic cell.

[0066] Comparative Example 4

[0067] Unlike Example 1, the molar ratio of stannous chloride dihydrate to copper nitrate trihydrate in S2 was 0:1, and the precatalyst obtained in S3 was named S-CuO. x The high-performance catalyst obtained in S5 was named S-Cu. Figure 1 The graph shows the selectivity of S-Cu in the electrocatalytic reduction of carbon dioxide to formic acid in an H-type electrolytic cell as a function of potential. Figure 2 The graph shows the variation of formic acid partial current density with potential in an H-type electrolytic cell.

[0068] Table 1 shows the dosage of each component in Examples 1-2 and Comparative Examples 1-4.

[0069] Table 1

[0070]

[0071]

[0072] Comparative Example 5

[0073] Compared with current CuSn catalysts of the same type and other state-of-the-art electrocatalytic carbon dioxide reduction catalysts, Table 2 shows the test results in an H-type reactor and Table 3 shows the test results in a flow reactor. The CuSn catalyst prepared in this application shows better electrocatalytic CO2 conversion performance in the electrocatalytic reduction of carbon dioxide to formic acid.

[0074] Table 2

[0075]

[0076]

[0077] Table 3

[0078]

[0079] In an H-type reactor, such as Figure 1 As shown, the main product of all catalysts was formic acid. With the increase of the molar ratio of copper nitrate trihydrate, the selectivity of each catalyst for formic acid showed a trend of first increasing and then decreasing. S-CuSn-II exhibited the highest formic acid selectivity at -1.0V, reaching 93.11%. Figure 2 As shown, the partial current density of formic acid also exhibits a significant increasing trend, with S-CuSn-II showing the highest partial current density, reaching approximately 55.69 mA / cm² at the optimal potential (-1.0 V). -2 It reaches 78.47 mA / cm at -1.2V. -2 .

[0080] Flow reactor testing, such as Figure 3 As shown, compared with S-Sn, S-CuSn-Ⅱ has a strength of 0.2-1.2 A / cm -2 It maintains a high formic acid selectivity of >85% over an ultra-wide current density range, with a maximum formic acid selectivity of 92.87% and a maximum formic acid partial current density of 1.03 A / cm². -2 Stability test results show that S-CuSn-Ⅱ is stable at 0.2 mA / cm². -2The S-CuSn-II catalyst exhibits superior performance in formic acid selectivity, current density, and stability, surpassing most of the most advanced catalysts currently available and meeting the standards for industrial applications (0.2 A / cm²). -2 (>100h). Therefore, the CuSn catalyst prepared by the method of the present invention has great potential for industrial application.

[0081] Comparative Example 1: In an H-type electrolytic cell, the optimal formic acid selectivity and the highest partial current density for S-Sn were 88.02% and 24.71 mA / cm², respectively. -2 It is significantly lower than that of S-CuSn-Ⅱ (94.34%, 78.47 mA / cm). -2 This indicates that S-CuSn-II has better electrocatalytic performance in the reduction of carbon dioxide to formic acid.

[0082] Comparative Example 2: In an H-type electrolytic cell, the optimal formic acid selectivity and the highest partial current density of S-CuSn-I were 89.79% and 67.45 mA / cm², respectively. -2 It is significantly lower than that of S-CuSn-Ⅱ (94.34%, 78.47 mA / cm). -2 This indicates that S-CuSn-II has better electrocatalytic performance in the reduction of carbon dioxide to formic acid.

[0083] Comparative Example 3: In an H-type electrolytic cell, the optimal formic acid selectivity and the highest partial current density of S-Cu / SnO2-Ⅲ were 79.40% and 56.69 mA / cm², respectively. -2 It is significantly lower than that of S-CuSn-Ⅱ (94.34%, 78.47 mA / cm). -2 This indicates that S-CuSn-II has better electrocatalytic performance in the reduction of carbon dioxide to formic acid.

[0084] Comparative Example 4: In an H-type electrolytic cell, the optimal formic acid selectivity and the highest partial current density of S-Cu were 84.12% and 30.63 mA / cm², respectively. -2 It is significantly lower than that of S-CuSn-Ⅱ (94.34%, 78.47 mA / cm). -2 This indicates that S-CuSn-II has better electrocatalytic performance in the reduction of carbon dioxide to formic acid.

[0085] Comparative Example 5: Compared with existing CuSn catalysts, the CuSn catalyst prepared in this application has the following advantages: the catalyst prepared in this application maintains a formic acid selectivity of over 90% even at current densities greater than 1 A. These results not only demonstrate the high specificity of the catalyst prepared in this application for formic acid formation, resulting in a highly concentrated product distribution, but also prove that the catalyst achieves extremely high catalytic activity and exhibits a faster product formation rate. Furthermore, the catalyst also demonstrates excellent long-term operational stability. In summary, this catalyst exhibits outstanding performance in terms of selectivity, activity, and stability, reaching the current industry-leading performance level. These performance indicators meet the industrial application requirements for efficient, rapid, specific, and stable catalytic processes.

[0086] In summary, the catalyst preparation process described in this application is simple, requiring no complex or expensive equipment. Its reaction conditions are mild and environmentally friendly, posing no pollution concerns, and its energy consumption is extremely low, meeting the requirements of sustainable development. It boasts high raw material utilization and high material yield, enabling large-scale industrial production. The prepared catalyst exhibits excellent catalytic selectivity, activity, and stability, reaching the current industry-leading performance level.

[0087] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing a high-performance CuSn catalyst, characterized in that: Includes the following steps: S1: Weigh a certain amount of sodium thiosulfate pentahydrate solid and dissolve it in deionized water to prepare solution No. 1, wherein the molar ratio of sodium thiosulfate pentahydrate to deionized water is 1:(150-200). S2: Weigh out a certain amount of tin salt and copper salt respectively, and dissolve them in deionized water to prepare solution No.

2. The molar ratio of the total amount of tin salt and copper salt to deionized water is 1:(20-30), and the molar ratio of tin salt to copper salt is 1:(0.43-1). S3: Mix the first solution prepared in S1 with the second solution prepared in S2 evenly, stir at room temperature for 1-1.5 h, centrifuge and wash several times, and vacuum dry to obtain CuSn precatalyst; S4: Weigh a certain amount of the CuSn precatalyst prepared in S3 and place it in a mixed solvent, while adding an appropriate amount of 5wt% Nafion solution, and ultrasonically disperse for 30-35 minutes to form a uniform catalyst ink. S5: Take an appropriate amount of the catalyst ink prepared in S4 and drop it onto hydrophobic carbon paper. After electrochemical reduction, a high-performance CuSn catalyst is obtained. The electrochemical reduction conditions are: apply a voltage of -1.0V vs. RHE, and pretreat in a carbon dioxide-saturated KHCO3 solution for 20-30 minutes to obtain a high-performance CuSn catalyst. The catalyst is composed of elemental Sn and Cu6Sn5 alloy.

2. The method for preparing a high-performance CuSn catalyst according to claim 1, characterized in that: The tin salt in S2 is any one of stannous chloride and stannous sulfate, or a combination of both.

3. The method for preparing a high-performance CuSn catalyst according to claim 2, characterized in that: The copper salt in S2 is any one or a combination of copper nitrate, copper chloride, and copper sulfate.

4. The method for preparing a high-performance CuSn catalyst according to claim 3, characterized in that: In S3, the vacuum drying temperature is 60-100℃, and the drying time is 2-6 hours.

5. A method for preparing a high-performance CuSn catalyst according to claim 4, characterized in that: In S4, the mixed solvent is a mixture of water and ethanol, wherein the volume ratio of water to ethanol is 1:(1-4).

6. A method for preparing a high-performance CuSn catalyst according to claim 5, characterized in that: In S4, the volume ratio of Nafion solution to the total amount of catalyst ink is 1:(20-50).

7. The method for preparing a high-performance CuSn catalyst according to claim 6, characterized in that: In S4, the concentration of the precatalyst is 8-10 mg / mL.

8. The method for preparing a high-performance CuSn catalyst according to claim 7, characterized in that: In S5, the loading of the precatalyst on the hydrophobic carbon paper is 1.5-2 mg / cm³. 2 .

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