A benzothiadiazole modified single-atom zirconium-doped copper electrode material, a preparation method therefor, and an application thereof

Abstract

The application relates to the development and technical field of electrocatalysts, and discloses a benzothiadiazole modified single-atom zirconium-doped metal copper electrode material and a preparation method and application thereof. The preparation method comprises the following steps: dissolving inorganic copper salt and inorganic zirconium salt, adding the inorganic copper salt and the inorganic zirconium salt into an alkaline solution, and performing hydrothermal reaction to obtain a single-atom zirconium-doped copper oxide precursor; dissolving benzothiadiazole, adding the benzothiadiazole into a dispersion solution of the single-atom zirconium-doped copper oxide precursor to obtain a mixed solution; spraying the mixed solution on a polytetrafluoroethylene film substrate loaded with copper nanoparticles to obtain a benzothiadiazole modified single-atom zirconium-doped copper oxide precursor electrode material; and performing electrochemical reduction treatment on the benzothiadiazole modified single-atom zirconium-doped copper oxide precursor electrode material to obtain a benzothiadiazole modified single-atom zirconium-doped metal copper electrode material. The electrode material is applied to an electro-reduction carbon dioxide reaction as a working electrode, exhibits excellent electro-reduction CO2 performance in an acidic environment, and realizes high-value-added C 2+ product with high selectivity.

Description

Technical Field

[0001] This invention relates to the field of electrocatalyst development and technology, specifically to a benzothiadiazole-modified single-atom zirconium-doped copper electrode material, its preparation method, and its application. Background Technology

[0002] The overexploitation of traditional fossil fuels has led to excessive carbon dioxide (CO2) emissions, causing serious environmental problems. Reducing CO2 emissions while simultaneously capturing and utilizing it is a crucial approach to mitigating these environmental issues. Among these methods, electrochemical reduction of CO2 into high-value-added multi-carbon (C2) fuels is particularly important. 2+ The byproducts of CO2 electroreduction, such as ethylene (C2H4), ethanol (C2H5OH), acetic acid (CH3COOH), and propanol (C3H7OH), are considered one of the most promising technological directions for achieving carbon cycling. Currently, most CO2 electroreduction reactions are carried out in alkaline or neutral electrolytes, inevitably leading to carbonate formation and reduced CO2 utilization efficiency. Furthermore, CO2 regeneration requires additional energy consumption, further lowering overall energy efficiency. Using acidic electrolytes for CO2 electroreduction can effectively address these issues; however, the competitive hydrogen evolution reaction from water electrolysis is more likely to occur in acidic environments, making it easier for CO2 to be converted into high-value-added carbon. 2+ The reduced product efficiency means that achieving the electroreduction of CO2 into high-value-added chemicals at industrial-grade current densities in acidic environments remains a significant challenge.

[0003] Copper-based catalysts possess the ability to deeply reduce CO2 to hydrocarbon products and exhibit moderate adsorption energies for most carbon-containing intermediates, making them widely used in the electroreduction of CO2. However, due to the linear structure of the CO2 molecule, the initial activation process is extremely difficult. Furthermore, the electroreduction of CO2 is a multi-step proton-coupled electron transfer process with slow reaction kinetics, limiting the effectiveness of single copper-based catalysts in generating specific C2 hydrocarbons. 2+ The product has low selectivity; therefore, it is crucial to develop a method that can effectively activate CO2 molecules and efficiently convert them into high-value-added C. 2+ The copper-based catalyst for the product is essential. Currently, introducing a second metal component to dope copper-based catalysts is one of the effective methods for their modification. For example, Chinese patent document CN118727045A discloses a rare-earth-doped nanoporous copper-based catalyst, its preparation method, and its application. Because rare-earth elements possess unique electronic orbitals and exhibit excellent electron transport capabilities, introducing them into nanoporous copper-based catalysts can significantly improve the C content. 2+ The product exhibits Faraday efficiency and effectively suppresses the competitive hydrogen evolution reaction, thus improving stability.

[0004] Carbon-carbon (CC) coupling is generally considered to be C 2+The key reaction steps in the product formation process determine the rate; however, the easy desorption of the intermediate *CO and the high energy barrier of the CC coupling reaction greatly limit its reaction kinetics. Therefore, enhancing the adsorption of the intermediate *CO and lowering the reaction energy barrier of CC coupling are effective methods to improve the formation rate of the key intermediate *COCO(*COCOH)₂. In recent years, the strategy of modifying the surface of electrode materials with organic molecules has become a direct and effective modification method, which can control the concentration of reactants on the catalyst surface and adjust the adsorption strength of reaction intermediates to improve performance, and has therefore been widely studied. For example, Chinese patent document CN117070980A discloses a copper functionalized with alkaline ionic liquid and its application in the electrocatalytic reduction of CO₂ to prepare multi-carbon products. By introducing alkaline ionic liquid to functionalize the copper electrode surface, the performance of electroreduction of CO₂ is significantly improved. 2+ The product has a Faraday efficiency greater than 70%, which is significantly better than that of the unmodified copper electrode.

[0005] Despite the high added value of C from electroreduction CO2 synthesis 2+ While some progress has been made in the study of the products, achieving high current density and high selectivity electroreduction of CO2 under acidic conditions still faces many challenges, especially for single C atoms. 2+ Further research is needed to explore the efficient directional synthesis of the product. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a benzothiadiazole-modified zirconium-doped metallic copper electrode material. The prepared benzothiadiazole-modified zirconium-doped metallic copper electrode material exhibits excellent electroreduction performance of CO2 under industrial-grade current density in an acidic environment.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0008] A method for preparing a benzothiadiazole-modified zirconium-doped metallic copper electrode material, the method comprising the following steps:

[0009] (1) After dissolving inorganic copper salt and inorganic zirconium salt, add alkaline solution and hydrothermally react to obtain a single-atom zirconium-doped copper oxide precursor;

[0010] (2) After dissolving benzothiadiazole, add it to the dispersion of zirconium-doped copper oxide precursor to obtain a mixed solution;

[0011] (3) Spray the mixed solution prepared in step (2) onto a polytetrafluoroethylene film substrate loaded with copper nanoparticles to obtain a benzothiadiazole-modified single-atom zirconium-doped copper oxide precursor electrode material.

[0012] (4) The benzothiadiazole-modified zirconium-doped copper oxide precursor electrode material prepared in step (3) is subjected to electrochemical reduction treatment to obtain benzothiadiazole-modified zirconium-doped metallic copper electrode material.

[0013] The preparation principle of the benzothiadiazole-modified single-atom zirconium-doped copper electrode material provided by this invention is as follows: In a uniformly dispersed mixed solution of inorganic copper salt and inorganic zirconium salt, the pH is adjusted to alkaline by adding an alkaline solution, so that Cu... 2+ Zr 4+ With OH - A precursor can be formed by combining and then subjected to a high-temperature hydrothermal reaction to obtain a single-atom zirconium-doped copper oxide precursor. This precursor is then mixed with benzothiadiazole and uniformly sprayed onto a polytetrafluoroethylene film substrate loaded with copper nanoparticles to obtain a benzothiadiazole-modified single-atom zirconium-doped copper oxide precursor electrode material. Finally, a benzothiadiazole-modified single-atom zirconium-doped metallic copper electrode material is obtained through constant-current electrochemical reduction. The doping of single-atom zirconium effectively modulates the electronic structure of metallic copper, enhancing the activation of CO2 molecules and enabling CO2 to convert to the *CO intermediate at a lower potential. The introduction of benzothiadiazole enhances the adsorption and stabilization of the *CO intermediate, thereby facilitating further CC-C coupling to generate high-value-added C. 2+ product.

[0014] The inorganic copper salt mentioned in step (1) is a soluble salt, preferably copper nitrate trihydrate.

[0015] The inorganic zirconium salt mentioned in step (1) is a soluble salt, preferably zirconium nitrate pentahydrate.

[0016] The molar ratio of zirconium salt to copper salt in step (1) is 0.005–0.03:1. This invention prepares copper oxide precursors with different zirconium doping ratios by varying the amount of zirconium salt used. When the molar concentration of zirconium salt is too low, its doping amount is too small, resulting in a minimal impact on the overall electronic structure of the catalyst and thus an insignificant activation performance for CO2 molecules. When the molar concentration of zirconium salt is too high, obvious zirconium dioxide particles appear on the copper oxide precursor, significantly reducing the electroreduction performance for CO2.

[0017] The alkaline solution mentioned in step (1) is a potassium hydroxide or sodium hydroxide solution, preferably a potassium hydroxide solution; the volume of the added potassium hydroxide solution is 10 mL and the molar concentration is 0.01 M.

[0018] The stirring time after adding the potassium hydroxide solution in step (1) is 15–30 min. Excessive stirring time will result in an uneven morphology of the copper oxide precursor, thus affecting the electrocatalytic CO2 performance. Preferably, the stirring time is 15 min.

[0019] The solvents used in step (2) to dissolve benzothiadiazole and the zirconium-doped copper oxide precursor are methanol, ethanol, and isopropanol. Preferably, the solvent is methanol.

[0020] In step (2), the mass ratio of benzothiadiazole to the zirconium-doped copper oxide precursor is 0.0017–0.01:1. When the mass ratio is low, the adsorption of the stable intermediate *CO is not significant; when the mass ratio is high, the competitive reaction becomes more pronounced, and hydrogen evolution increases significantly. Preferably, the mass ratio of benzothiadiazole to the zirconium-doped copper oxide precursor is 0.0034–0.01:1, which is beneficial for further improving the performance of electroreduction of CO2.

[0021] The thickness of the copper nanoparticle layer loaded on the polytetrafluoroethylene film in step (3) is 100-200 nm. Preferably, the thickness of the copper nanoparticle layer is 200 nm.

[0022] In step (3), the loading amount of benzothiadiazole-modified zirconium-doped copper oxide precursor on a polytetrafluoroethylene film substrate loaded with copper nanoparticles is 0.5–1 mg cm⁻¹. -2 Preferably, the loading amount of the benzothiadiazole-modified zirconium-doped copper oxide precursor is 1 mg cm⁻¹. -2 .

[0023] The constant current density for the electrochemical reduction described in step (4) is 50–100 mA cm⁻¹. -2 The time is 100–300 s. Preferably, the constant current density of the electrochemical reduction is 100 mA cm⁻¹. -2 The time is 300 seconds.

[0024] The present invention also provides a benzothiadiazole-modified zirconium-doped metallic copper electrode material obtained by the above preparation method.

[0025] In the benzothiadiazole-modified zirconium-doped metallic copper electrode material, the atomic ratio of zirconium to copper is 0.005 to 0.03:1, and the thickness of the copper nanoparticle layer loaded on the polytetrafluoroethylene film is 100 to 200 nm.

[0026] The present invention also provides a copper electrode material modified with the above-mentioned benzothiadiazole and doped with zirconium as a working electrode for use in the electroreduction of CO2 reaction.

[0027] Furthermore, the benzothiadiazole-modified zirconium-doped copper electrode material is used as a working electrode to achieve the electroreduction of CO2 at industrial-grade current densities in an acidic environment.

[0028] The benzothiadiazole-modified zirconium-doped metallic copper electrode material provided by this invention, when used as a working electrode, exhibits excellent industrial-grade current density (200–1000 mA cm⁻¹) in acidic environments. -2 Electroreduction performance of CO2.

[0029] In the benzothiadiazole-modified zirconium-doped copper electrode material provided by this invention, the zirconium single-atom doping effectively enhances the activation of CO2 molecules at low potentials, providing more reaction intermediates *CO for subsequent CC coupling reactions. Simultaneously, benzothiadiazole modification effectively stabilizes the intermediate *CO, thereby enhancing *CO adsorption to inhibit the direct escape of *CO to form carbon monoxide (CO), effectively promoting CC coupling and increasing C. 2+ The selectivity of the products is of great significance for realizing the electroreduction of CO2 to produce high-value-added chemicals under industrial conditions in acidic environments.

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

[0031] (1) The benzothiadiazole-modified zirconium-doped copper electrode material provided by the present invention achieves high selective electroreduction performance of CO2 in acidic environment;

[0032] (2) The benzothiadiazole-modified zirconium-doped copper electrode material provided by this invention effectively modulates the electronic structure of copper through zirconium doping, enhancing CO2 molecule activation at low potentials. The introduction of benzothiadiazole helps stabilize the intermediate *CO and enhances the adsorption of the *CO intermediate, thereby promoting the subsequent CC coupling to generate C. 2+ The product exhibits excellent performance in the electroreduction of CO2 under acidic conditions. Attached Figure Description

[0033] Figure 1 Zr, the precursor prepared in Example 1 1.0％ Transmission electron microscopy image of CuO;

[0034] Figure 2 Zr, the precursor prepared in Example 1 1.0％ - Spherical aberration correction of CuO - High-angle dark-field scanning transmission electron microscopy image;

[0035] Figure 3 The electrode material Zr prepared in Example 1 1.0％ X-ray diffraction pattern of Cu;

[0036] Figure 4 The electrode materials prepared for Example 1 and Comparative Example 1 showed an 100–700 mA cm⁻¹ in an environment with pH = 1.5 in the application example. -2Faraday efficiency of different products obtained by electroreduction of CO2 at current density.

[0037] Figure 5 The electrode materials prepared in Examples 1-3 achieved 600 mA cm⁻¹ in an application example at pH 1.5. -2 Faraday efficiency of different products obtained by electroreduction of CO2 at current density

[0038] Figure 6 The electrode materials prepared for Comparative Examples 1-4 were tested in an application example with CO, H2, C2H4, and C in a pH=1.5 environment. 2+ The Faraday efficiency of the product.

[0039] Figure 7 The electrode materials prepared for Comparative Examples 1 and 4 achieved an 100–700 mA cm⁻¹ in an environment with pH = 1.5 in the application example. -2 The Faraday efficiency and reaction potential of CO at current density.

[0040] Figure 8 The electrode material prepared in Example 1 was tested at 300 mA cm⁻¹ in an environment with pH = 1.5 in the application example. -2 Stability test at current density. Detailed Implementation

[0041] 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. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention. Modifications or equivalent substitutions made by those skilled in the art based on their understanding of the technical solutions of this invention, without departing from the spirit and scope of the technical solutions of this invention, should all be covered within the protection scope of this invention. The raw materials used in the following specific embodiments are all commercially available.

[0042] Example 1

[0043] (1) Weigh 1208 mg of copper nitrate trihydrate solid particles and 21.5 mg of zirconium nitrate pentahydrate solid particles, dissolve them in 50 mL of deionized water, stir at room temperature until transparent, then add 10 mL of 0.01 M potassium hydroxide solution dropwise and stir for 15 min; transfer the resulting mixed solution to a 50 mL hydrothermal reactor and hydrothermally react at 120 °C for 4 h, then centrifuge, wash with water and ethanol more than 3 times each, and finally dry in a vacuum oven at 60 °C for 12 h to obtain a single-atom zirconium-doped copper oxide precursor.

[0044] (2) Weigh 20 mg of the single-atom zirconium-doped copper oxide precursor obtained in step (1) and disperse it in 3 mL of methanol and 60 μL of Nafion dispersion. Dissolve benzothiadiazole in methanol solution to obtain a 2.5-15 mM mixed solution. Then take 100 μL of benzothiadiazole and methanol mixed solution with a molar concentration of 5 mM and add it to the dispersion of single-atom zirconium-doped copper oxide precursor. After mixing evenly, the mass ratio of benzothiadiazole to single-atom zirconium-doped copper oxide precursor is 0.0034:1.

[0045] (3) Measure the mixed solution prepared in step (2) and spray it evenly to a depth of 2*2cm. 2 The loading amount of the polytetrafluoroethylene film substrate loaded with copper nanoparticles was determined to be 1 mg cm⁻¹ by weighing the substrate before and after loading. -2 In a 3M KCl (pH=1.5) electrolyte, 100mA cm -2 At a constant current density, a constant current electrochemical reduction reaction was carried out for 300 s to obtain a benzothiadiazole-modified zirconium-doped metallic copper electrode material.

[0046] The macroscopic morphology of the single-atom zirconium-doped copper oxide precursor prepared above was observed by transmission electron microscopy, and the results are as follows: Figure 1 As shown, its morphological structure is sheet-like. The aberration-corrected high-angle dark-field scanning transmission electron microscope image is shown below. Figure 2 As shown, zirconium is clearly doped into the copper oxide precursor lattice in a single-atom form. The X-ray diffraction pattern of the benzothiadiazole-modified single-atom zirconium-doped copper electrode material prepared in this embodiment is shown below. Figure 3 As shown, the characteristic peaks of the crystalline phase of metallic copper can be observed, indicating the successful preparation of benzothiadiazole-modified single-atom zirconium-doped metallic copper electrode material.

[0047] Example 2

[0048] According to the preparation process of Example 1, the molar concentration of the benzothiadiazole and methanol mixed solution in step (2) was changed to 2.5 mM, and the mass ratio of benzothiadiazole to the single-atom zirconium-doped copper oxide precursor was 0.0017:1.

[0049] Example 3

[0050] Following the preparation process of Example 1, the molar concentration of the benzothiadiazole and methanol mixed solution in step (2) was changed to 15 mM, resulting in a mass ratio of benzothiadiazole to the single-atom zirconium-doped copper oxide precursor of 0.01:1.

[0051] Comparative Example 1

[0052] Following the preparation process of Example 1, without performing step (2), 100 μL of a 5 mM benzothiadiazole mixed solution with methanol was measured to obtain a single-atom zirconium-doped copper electrode material.

[0053] Comparative Example 2

[0054] According to the preparation process of Example 1, the mass of zirconium nitrate pentahydrate particles in step (1) was changed to 10.7 mg, and the step (2) of measuring 100 μL of a 5 mM benzothiadiazole and methanol mixture was not performed.

[0055] Comparative Example 3

[0056] According to the preparation process of Example 1, the mass of zirconium nitrate pentahydrate particles in step (1) was changed to 64.4 mg, and the step (2) of measuring 100 μL of a 5 mM benzothiadiazole and methanol mixture was not performed.

[0057] Comparative Example 4

[0058] According to the preparation process of Example 1, the mass of zirconium nitrate pentahydrate particles in step (1) was changed to 0 mg, and the step (2) of measuring 100 μL of a 5 mM benzothiadiazole and methanol mixture was not performed.

[0059] Application example: Electroreduction of CO2 at industrial-grade current density in acidic environments

[0060] First, the electrode material prepared above was placed as the working electrode in a three-electrode flow electrolysis cell measuring device. This device consists of two compartments separated by a cation exchange membrane (Nafion 117). The pH of a 3.0 M KCl solution was adjusted to 1.5 using 0.5 M H₂SO₄ solution, which was then used as the cathode electrolyte, and the 0.05 M H₂SO₄ solution was used as the anolyte. The counter electrode was a platinum sheet, and the reference electrode was a silver / silver chloride electrode.

[0061] Cyclic voltammetry (CV) activation: A Shanghai Chenhua CHI 760E electrochemical workstation was used with a CV program. The test range was -0.5 to -1.9 V vs. RHE, and the scan rate was 50 mV / s. -1 After 40 cyclic scans, the electrode reaches a stable state.

[0062] Linear sweep voltammetry (LSV) test: After CV activation, switch the program to LSV, with a test range of -0.5 to -1.9 V vs. RHE, and a scan rate of 5 mV / s. -1 .

[0063] Faraday efficiency (FE) test: Switch the program to constant current-time test. During the constant current test, use gas chromatography to determine the concentration of gaseous products and calculate the Faraday efficiency of the gaseous products. Online quantification is performed using gas chromatography (GC, Fuli 9790II). 1 The Faraday efficiency of liquid products was analyzed using an H NMR spectrometer, employing the internal standard method, i.e., using dimethyl sulfoxide as the standard.

[0064] The benzothiadiazole-modified zirconium-doped copper electrode material prepared in Example 1 exhibited excellent electroreduction performance for CO2 in an acidic environment, as shown in the following results. Figure 4 As shown, in an electrolyte with pH = 1.5, at 600 mA cm⁻¹ -2 At current density, C2H4 and C 2+ The product selectivity was as high as 56.0% and 74.9%, respectively. Compared with the electroreduction CO2 performance of Comparative Example 1 (zirconium-free copper and benzothiadiazole-modified copper electrode materials), the overall C 2+ The product's Faraday efficiency was improved by 17.3%, making industrial application possible.

[0065] The electrode materials prepared in Examples 1-3 were subjected to a 600 mA cm⁻¹ test. -2 The electroreduction performance of CO2 at different current densities was compared, and the results are as follows: Figure 5 As shown, the benzothiadiazole-modified zirconium-doped copper electrode material prepared in Example 1 performs better than that in Examples 2 and 3 in an acidic environment.

[0066] The electrode materials prepared in Comparative Examples 1-4 were subjected to a 600 mA cm⁻¹ test. -2 The electroreduction performance of CO2 at different current densities was compared, and the results are as follows: Figure 6 As shown, the single-atom zirconium-doped copper electrode material prepared in Comparative Example 1 performs better than Comparative Examples 2-4 in an acidic environment.

[0067] The single-atom zirconium-doped copper electrode materials prepared in Comparative Examples 1 and 4, and the undoped copper electrode materials, were subjected to an A / cm² test at 100–700 mA. -2 The performance under different current densities was compared, and the results are as follows: Figure 7 As shown, Comparative Example 1 has a lower reaction potential at the same current density, indicating a stronger activation effect on CO2 molecules.

[0068] The stability of Example 1 was tested in a flowing electrolyzer, and the results are as follows: Figure 8 As shown, at 300mA cm -2 It can operate stably for 24 hours at a current density, and the Faraday efficiency of C2H4 remains above 40%.

Claims

1. A method for preparing a benzothiadiazole-modified zirconium-doped metallic copper electrode material, characterized in that, The preparation method includes the following steps: (1) After dissolving inorganic copper salt and inorganic zirconium salt, add alkaline solution and hydrothermally react to obtain a single-atom zirconium-doped copper oxide precursor; (2) After dissolving benzothiadiazole, add it to the dispersion of zirconium-doped copper oxide precursor and mix to obtain a mixed solution; (3) The mixed solution prepared in step (2) is sprayed onto a polytetrafluoroethylene film substrate loaded with copper nanoparticles to obtain a benzothiadiazole-modified single-atom zirconium-doped copper oxide precursor electrode material. (4) The benzothiadiazole-modified zirconium-doped copper oxide precursor electrode material prepared in step (3) is subjected to electrochemical reduction treatment to obtain benzothiadiazole-modified zirconium-doped metallic copper electrode material. In step (1), the molar ratio of the inorganic zirconium salt to the inorganic copper salt is 0.005~0.03:1; In step (2), the mass ratio of the benzothiadiazole to the zirconium-doped copper oxide precursor is 0.0017~0.01:1; In step (4), the constant current density for electrochemical reduction is 50~100 mA·cm⁻¹ in an electrolyte of 3 M KCl and pH = 1.

5. -2 The duration is 100~300 s.

2. The method for preparing benzothiadiazole-modified zirconium-doped metallic copper electrode material according to claim 1, characterized in that, In step (3), the thickness of the copper nanoparticle layer loaded on the polytetrafluoroethylene film is 100~200 nm.

3. The method for preparing benzothiadiazole-modified zirconium-doped metallic copper electrode material according to claim 1, characterized in that, In step (3), the loading amount of benzothiadiazole-modified zirconium-doped copper oxide precursor on the polytetrafluoroethylene film-supported copper nanoparticle substrate is 0.5~1 mg·cm⁻¹. -2 .

4. A benzothiadiazole-modified zirconium-doped metallic copper electrode material obtained by any of the preparation methods described in claims 1-3.

5. The benzothiadiazole-modified zirconium-doped metallic copper electrode material according to claim 4, characterized in that, In the benzothiadiazole-modified zirconium-doped copper electrode material, the atomic ratio of zirconium to copper is 0.005~0.03:1, and the thickness of the copper nanoparticle layer loaded on the polytetrafluoroethylene film is 100~200 nm.

6. A benzothiadiazole-modified zirconium-doped metallic copper electrode material as described in claim 4 is used as a working electrode in the electroreduction of carbon dioxide.

7. The application according to claim 6, characterized in that, The benzothiadiazole-modified zirconium-doped copper electrode material described above is used as a working electrode to achieve the electroreduction of carbon dioxide at industrial-grade current densities in an acidic environment.

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