A carbon-based Cu-Ni dual-atom cluster catalyst, its preparation method and application

Abstract

The present invention relates to the technical field of multiphase catalysts, and specifically relates to a carbon-based Cu-Ni dual-atom cluster catalyst, a preparation method thereof, and an application thereof. The preparation method includes the following steps: mixing an aqueous solution of thiosemicarbazide, magnesium chloride hexahydrate, an alkali, a nickel salt, a copper salt, and a saccharide compound, and performing freeze-drying to obtain a precursor; sequentially performing preheating treatment, first pyrolysis, and second pyrolysis on the precursor to obtain a carbon-based Cu-Ni dual-atom catalyst; formulating the carbon-based Cu-Ni dual-atom catalyst into a slurry, adhering it to a current collector, and performing in-situ electrolysis treatment to obtain a carbon-based Cu-Ni dual-atom cluster catalyst. The preparation method of the present invention can not only precisely control the number of metal atoms in the metal atom cluster, but also realize the reconstruction of Cu-Ni dual-atom sites, overcoming the problems that it is difficult to control the size of metal particles and it is difficult to exert the advantages of atomic-level catalysts in the traditional high-temperature carbonization method.

Description

Technical Field

[0001] The present invention relates to the technical field of multiphase catalysts, and in particular to a carbon-based Cu-Ni diatomic cluster catalyst and a preparation method and application thereof. Background Art

[0002] The electrochemical reduction of carbon dioxide technology, driven by renewable energy power generation, is committed to the production of high value-added chemicals. In this process, carbon monoxide, as the main product of the electrochemical reduction of carbon dioxide, not only occupies a key position in Fischer-Tropsch synthesis, but also exhibits excellent carbon storage efficiency. However, the main challenge facing the current electrochemical reduction of carbon dioxide technology is that the energy efficiency and product selectivity have not yet met the actual requirements of industrialization. Copper, as an element with abundant reserves on the earth, is regarded as a catalyst for the efficient conversion of CO2 into hydrocarbons. Cu-based atomic-level catalysts show great potential to control reaction pathways in complex catalytic processes due to the designability of their electronic properties. Compared with single-atom catalysts, multi-atom catalysts have different coordination environments, geometric configurations, and metal-metal or metal-support interactions.

[0003] Polyatomic cluster catalysts are a new type of heterogeneous catalysts with atomic dispersion. Polyatomic cluster catalysts are between atoms and nanoparticles. They are composed of metal clusters with precise atomic numbers, namely Mn, n=3~20, monodispersed on a carrier. They have the advantages of high atomic utilization, structural diversity and metal synergy, and are regarded as multifunctional boosters for heterogeneous catalysis. In addition to the simple combination of single-atom catalysts, they are also able to improve activity through synergy between adjacent atoms. At the same time, the multiple active sites of the catalytic center diversify their binding modes with adsorbates and provide opportunities for catalyzing complex reactions with multiple products. The coordination microenvironment of the atomic clusters in polyatomic cluster catalysts includes metal type, atomic number, non-metal coordination and aggregation state. Adjusting its microenvironment will lead to significant size effects and polarized charge distribution, thereby improving its catalytic reaction performance.

[0004] At present, the atomic clusters in the multi-atom cluster catalysts obtained by the traditional high-temperature carbonization method have a large diameter, which makes it difficult to give full play to the advantages of atomic-level metals and is not conducive to the identification of true active centers; even if atomic clusters can be directly synthesized, the number and aggregation state of metal atoms in the atomic clusters are relatively random and difficult to control. Summary of the invention

[0005] Aiming at the problems existing in the prior art, the present invention provides a carbon-based Cu-Ni dual-atom cluster catalyst, a preparation method thereof and an application thereof. In the present invention, an aqueous solution of thiosemicarbazide, magnesium chloride hexahydrate, an alkali, a nickel salt, a copper salt and a saccharide compound are mixed and then freeze-dried to obtain a precursor; subsequently, in an inert atmosphere, the precursor is sequentially subjected to preheating treatment, first pyrolysis and second pyrolysis to obtain a carbon-based Cu-Ni dual-atom catalyst; finally, the carbon-based Cu-Ni dual-atom catalyst is subjected to in-situ electrolysis treatment to obtain a carbon-based Cu-Ni dual-atom cluster catalyst. The present invention realizes the reconstruction of Cu-Ni dual-atom sites through in-situ electrolysis treatment, which can not only accurately control the number of metal atoms in the metal atom cluster, effectively reduce the existence of single-atom sites, but also solve the problems that it is difficult to control the size of metal particles in the traditional high-temperature carbonization method and it is difficult to exert the advantages of atomic-level catalysts.

[0006] In order to achieve the above object, the technical solution adopted in the present application is as follows:

[0007] The first object of the present invention is to provide a preparation method of a carbon-based Cu-Ni dual-atom cluster catalyst, comprising the following steps:

[0008] S1. Mix an aqueous solution of thiosemicarbazide, magnesium chloride hexahydrate, an alkali, a nickel salt, a copper salt and a saccharide compound. During the mixing process, thiosemicarbazide coordinates with Ni 2+ and Cu 2+ to form a NiCu complex containing metal cyanide groups, and the NiCu complex provides a basis for the formation of NiCu dual-atom sites; at the same time, magnesium chloride hexahydrate reacts with the alkali to generate Mg(OH)2 and a chloride salt, and the saccharide compound serves as a carbon skeleton to anchor and disperse the NiCu complex, solving the aggregation of the NiCu complex while obtaining a mixed hydrogel.

[0009] S2. Freeze-dry the mixed hydrogel. When freeze-drying, the water in the mixed hydrogel sublimes, leaving a porous structure to obtain a precursor; compared with freeze-drying, other heating drying methods will cause the mixed hydrogel to agglomerate, resulting in a reduction in the pore structure, thereby reducing the pore structure of the precursor and being unfavorable for mass transfer in the catalytic process.

[0010] S3. Under an inert atmosphere, preheat the precursor first and then perform the first pyrolysis. During the preheating treatment and the first pyrolysis, thiosemicarbazide in the precursor decomposes and interacts with the saccharide compound to be jointly converted into a porous carbon skeleton; at the same time, Mg(OH)2 decomposes to form a templating agent MgO, providing an ordered support structure for the NiCu complex; at the same time, the chloride salt is reconstructed, and MgO and the chloride salt can decompose Ni and Cu, preventing them from directly forming simple substances, and generating NiCu dual-atom-loaded porous carbon dispersed in the porous carbon skeleton on the MgO template to obtain NiCu dual-atom porous carbon.

[0011] S4. Pickle the NiCu dual-atom porous carbon to remove MgO, chloride salts, and excessive metal particles or metal oxides, obtaining an intermediate.

[0012] S5. Subject the intermediate to a second pyrolysis under an inert atmosphere to remove the oxygen-containing functional groups on the surface of the intermediate, while increasing the conductivity of the intermediate and promoting the rearrangement and aggregation of Cu atoms and Ni atoms on the porous carbon framework, obtaining a carbon-based Cu-Ni dual-atom catalyst.

[0013] S6. Prepare the carbon-based Cu-Ni catalyst into a slurry, adhere it to a current collector, and perform in-situ electrolysis treatment. During the in-situ electrolysis process, the Cu-Ni dual-atom sites in the NiCu complex are reconstructed, that is, Cu ions are reduced to metallic Cu atoms at a negative potential and detached from the Cu-Ni dual-atom coordination structure, becoming Cu-Ni dual-atom cluster sites enriched with Cu atoms, obtaining a carbon-based Cu-Ni dual-atom cluster catalyst.

[0014] Preferably, the conditions for the in-situ electrolysis treatment are: electrolyzing for 2 h to 4 h at -0.5 V to -1.2 V; among them, the negative increase in voltage is beneficial to the increase in the number of metal atoms; copper atoms have a relatively high reduction potential, that is, Cu 2+ / Cu 0 is +0.34 V, Cu + / Cu 0 is +0.52 V. In a negative potential environment, copper ions will be preferentially reduced to metallic Cu atoms. This process leads to a weakened adsorption force between Cu atoms and the carbon substrate, thereby triggering the migration of Cu atoms and causing them to detach from the original Cu-Ni coordination structure; the role of the electric field is that it accelerates the migration and collision of Cu atoms or Cu ions through the action of electrostatic force. The Cu atoms that have detached from the original carrier will spontaneously agglomerate due to the reduction of surface energy, thereby forming Cu-based nanoclusters. On the other hand, in a water electrolysis system, when a relatively low voltage is applied, active hydrogen radicals will be generated on the cathode surface. These radicals will attack the Cu-Ni coordination structure, thereby weakening the anchoring effect of the carrier on Cu atoms and further promoting the migration of Cu atoms; however, when the voltage is low, the surface energy of copper will decrease accordingly, which will exacerbate the Ostwald ripening process, that is, smaller particles dissolve and redeposit on larger particles, which is not conducive to the stable existence of copper atoms.

[0015] Preferably, the mass ratio of thiosemicarbazide, nickel salt, and copper salt in the mixed hydrogel is 1 to 3: 0.2 to 0.6: 0.1 to 0.6, the mass ratio of thiosemicarbazide to saccharide compounds is 1 to 3: 0.3 to 1, and the mass ratio of thiosemicarbazide, magnesium chloride hexahydrate, and base is 1 to 3: 0.5 to 2: 0.5 to 2.

[0016] Preferably, the nickel salt is selected from nickel acetylacetonate, nickel acetate, nickel nitrate or nickel sulfate.

[0017] Preferably, the reagent for pickling treatment is selected from nitric acid or sulfuric acid, and the pickling treatment time is 10 h to 15 h.

[0018] Preferably, the concentration of the reagent for pickling treatment is 0.5 mol / L to 3 mol / L; if the concentration is too low, the removal of the MgO template is incomplete and metal particles remain; if the concentration is too high, excessive corrosion of the metal will occur, resulting in a significant decrease in the metal loading.

[0019] Preferably, the conditions for preheating treatment are: heating to 350 °C to 450 °C at a heating rate of 2 °C / min to 5 °C / min and preheating for 1 h to 3 h; among them, if the heating rate is too fast or the temperature is too high, a large amount of thiosemicarbazide is likely to volatilize.

[0020] Preferably, the conditions for the first pyrolysis are: heating to 800 °C to 1000 °C at a heating rate of 4 °C / min to 10 °C / min and then pyrolyzing for 1 h to 3 h; among them, the first pyrolysis rapidly and fully carbonizes the precursor into a porous carbon skeleton; when the temperature is higher than 1000 °C, the pore structure of NiCu dual-atom porous carbon becomes less, and at the same time the metal agglomerates into a single substance; when the temperature is lower than 800 °C, the conductivity of NiCu dual-atom porous carbon is low.

[0021] Preferably, the conditions for the second pyrolysis are: heating to 800 °C to 1200 °C at a heating rate of 2 °C / min to 5 °C / min and then pyrolyzing for 1 h to 3 h; re-carbonizing the intermediate and effectively decomposing oxygen-containing functional groups, improving the conductivity of the carbon-based Cu-Ni dual-atom catalyst, and at the same time enhancing the coordination and anchoring effect of NiCu dual atoms on the porous carbon skeleton; when the temperature is higher than 1200 °C, the metal agglomerates into a single substance; when the temperature is lower than 800 °C, the elimination of oxygen-containing functional groups is incomplete.

[0022] Preferably, the conditions for the mixing treatment are: stirring at 55 °C to 95 °C for 3 h to 4 h.

[0023] The second object of the present invention is to provide a carbon-based Cu-Ni dual-atom cluster catalyst prepared by the above preparation method.

[0024] Preferably, the number of metal atoms in the carbon-based Cu-Ni dual-atom cluster catalyst is 4 to 9.

[0025] Preferably, in the carbon-based Cu-Ni dual-atom cluster catalyst, the diameter of the Cu-Ni dual-atom cluster is less than 2 nm.

[0026] The third object of the present invention is to provide the use of the above-mentioned carbon-based Cu-Ni diatomic cluster catalyst in the preparation of electrocatalytic CO2 reduction reaction catalyst.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention provides a method for preparing a carbon-based Cu-Ni diatomic cluster catalyst, comprising mixing an aqueous solution of thiosemicarbazide, magnesium chloride hexahydrate, an alkali, a nickel salt, a copper salt and a carbohydrate compound to obtain a mixed hydrogel; then freeze-drying the mixture to obtain a precursor; preheating the precursor under an inert atmosphere, and then performing a first pyrolysis to obtain NiCu diatomic porous carbon, which is then acid-washed to obtain an intermediate; placing the intermediate under an inert atmosphere and performing a second pyrolysis to obtain a carbon-based Cu-Ni diatomic catalyst; formulating the carbon-based Cu-Ni diatomic catalyst into a slurry, adhering the slurry to a current collector, and performing an in-situ electrolysis treatment, wherein during the in-situ electrolysis, Cu ions are reduced to metallic Cu atoms under a negative potential, and are separated from the Cu-Ni coordination structure to become Cu-Ni diatomic cluster sites enriched with Cu atoms, thereby obtaining a carbon-based Cu-Ni diatomic cluster catalyst. The present invention is based on the method of in-situ electrolysis treatment. By adjusting the applied voltage to adjust the in-situ electrolysis parameters, it not only achieves precise control of the number of metal atoms in the metal atom cluster, but also effectively reduces the presence of single-atom sites, thereby simplifying the types of metal active sites and improving their purity and efficiency. In addition, the present invention also effectively solves the problem that the size of metal particles is difficult to control and it is difficult to give full play to the advantages of atomic-level catalysts in the traditional high-temperature carbonization method.

[0029] 2. The carbon-based Cu-Ni diatomic cluster catalyst of the present invention exists in an atomic-level precision and ligand-protected manner, forming a nanocluster structure with a diameter of less than 2nm. The number of metal atoms in these nanoclusters is clear and controlled between 4 and 9. In addition, the carbon-based Cu-Ni diatomic cluster catalyst also significantly enhances the catalytic activity and stability of the carbon-based Cu-Ni diatomic cluster, showing excellent catalytic performance.

[0030] 3. The carbon-based Cu-Ni diatomic cluster catalyst of the present invention can not only solve the problem of lack of metal synergy and poor catalytic activity of conventional atomic-level catalysts, but also promote the electrocatalytic CO2 reduction performance.

[0031] At a potential of -0.9 V vs. RHE, the carbon-based Cu-Ni diatomic catalyst reorganizes into a carbon-based Cu-Ni diatomic cluster catalyst composed of 4 to 6 Cu atoms and 1 Ni atom, with a CO Faraday efficiency of up to 96.9% and a stability of up to 120 h. When the applied potential is -1.2 V vs. RHE, the nanoclusters of the carbon-based Cu-Ni diatomic cluster catalyst are upgraded to 6 to 8 Cu atoms. Description of the Drawings

[0032] Figure 1 XRD patterns of carbon-based Cu-Ni dual-atom catalyst, carbon-based Ni single-atom catalyst, and carbon-based Cu single-atom catalyst.

[0033] Figure 2 Raman spectra of carbon-based Cu-Ni dual-atom catalyst, carbon-based Ni single-atom catalyst, and carbon-based Cu single-atom catalyst.

[0034] Figure 3 SEM image of carbon-based Cu-Ni dual-atom catalyst.

[0035] Figure 4 TEM image of carbon-based Cu-Ni dual-atom catalyst.

[0036] Figure 5 HAADF-STEM images of carbon-based Cu-Ni dual-atom catalyst and carbon-based Cu-Ni dual-atom cluster catalysts prepared in Example 1 and Example 4. Among them, (a) is the HAADF-STEM image of the carbon-based Cu-Ni dual-atom catalyst, (b) is the HAADF-STEM image of the carbon-based Cu-Ni dual-atom cluster catalyst prepared in Example 4; (c) is the HAADF-STEM image of the carbon-based Cu-Ni dual-atom cluster catalyst prepared in Example 1.

[0037] Figure 6 Faraday efficiency diagrams of carbon-based Cu-Ni dual-atom cluster catalysts prepared in Examples 1 to 8, Ni-NC of Comparative Examples 1 to 8, and Cu-NC of Comparative Examples 9 to 16.

[0038] Figure 7 Current density diagrams of carbon-based Cu-Ni dual-atom cluster catalysts prepared in Examples 1 to 8, Ni-NC of Comparative Examples 1 to 8, and Cu-NC of Comparative Examples 9 to 16.

[0039] Figure 8 Stability diagram of the carbon-based Cu-Ni dual-atom cluster catalyst prepared in Example 4.

[0040] Figure 9 In-situ XAFS diagrams of Cu element in carbon-based Cu-Ni dual-atom cluster catalysts prepared in Examples 1 to 7. Among them, a is the structural spectrum, b is the extended spectrum, and the inset in Figure a is the local enlarged view of the Cu element absorption edge.

[0041] Figure 10The in-situ XAFS graphs of the Ni element in the carbon-based Cu-Ni diatomic cluster catalysts prepared in Examples 1 to 7, wherein a is the structural spectrum, b is the extended spectrum, and the inset in Figure a is a local enlarged view of the absorption edge of the Ni element.

[0042] Figure 11 1 and 2 are the extended XAFS fitting graphs of the carbon-based Cu-Ni diatomic catalyst and the carbon-based Cu-Ni diatomic cluster catalysts prepared in Example 1, Example 4 and Example 6, a is the carbon-based Cu-Ni diatomic catalyst, b is the extended XAFS fitting graph of Example 6, c is the extended XAFS fitting graph of Example 4, and d is the extended XAFS fitting graph of Example 1. DETAILED DESCRIPTION

[0043] The technical solution of the present invention will be clearly and completely described below in combination with the data in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] The following experimental methods and detection methods, unless otherwise specified, are conventional methods; the following reagents and raw materials, unless otherwise specified, are commercially available reagents and raw materials.

[0045] In the prior art, the synthesis method of multi-atom cluster catalysts mainly relies on the traditional high-temperature carbonization method, but the diameter of the atomic clusters in the multi-atom cluster catalysts obtained by this method is relatively large, which makes it difficult to give full play to the advantages of atomic-level metals and is not conducive to the identification of true active centers. At the same time, even if the atomic clusters can be directly synthesized, the number and aggregation state of metal atoms in the atomic clusters are relatively random, making it difficult to achieve precise control.

[0046] In view of the problems existing in the above-mentioned prior art, the present invention provides a method for preparing a carbon-based Cu-Ni diatomic cluster catalyst, comprising the following steps: mixing an aqueous solution of thiosemicarbazide, magnesium chloride hexahydrate, an alkali, a nickel salt, a copper salt and a carbohydrate compound to obtain a mixed hydrogel, and then freeze-drying to obtain a precursor; preheating the precursor under an inert atmosphere, and then performing a first pyrolysis to obtain NiCu diatomic porous carbon, and then performing an acid wash treatment to obtain an intermediate; placing the intermediate under an inert atmosphere and performing a second pyrolysis to obtain a carbon-based Cu-Ni diatomic catalyst; formulating the carbon-based Cu-Ni diatomic catalyst into a slurry, adhering it to a current collector, and performing an in-situ electrolysis treatment. During the in-situ electrolysis, Cu ions are reduced to metallic Cu atoms under a negative potential, and are separated from the Cu-Ni coordination structure to become Cu-Ni diatomic cluster sites enriched with Cu atoms, thereby obtaining a carbon-based Cu-Ni diatomic cluster catalyst.

[0047] The preparation method of the present invention can not only precisely control the number of metal atoms in the metal atom cluster, but also effectively reduce the existence of single atomic sites, thereby simplifying the types of metal active sites and improving their purity and efficiency. At the same time, the reconstruction of Cu-Ni dual atomic sites is realized through in-situ electrolysis treatment, solving the problems that it is difficult to control the size of metal particles and difficult to exert the advantages of atomic-level catalysts in the traditional high-temperature carbonization method.

[0048] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0049] In the embodiment of the present invention, the carbon-based Cu-Ni dual-atomic catalyst is prepared according to the following method:

[0050] Method 1:

[0051] S1. Weigh 2 g of thiosemicarbazide and transfer it to a three-necked flask containing 40 mL of water; then, place the three-necked flask in an oil bath, heat it to 55 °C and stir for 20 min; afterwards, weigh 1.34 g of magnesium chloride hexahydrate, 1.18 g of potassium hydroxide, 0.4 g of nickel acetate and 0.32 g of copper acetate, and add them to the three-necked flask in sequence, and continue to stir at 85 °C for 30 min; finally, add 0.53 g of chitosan and continue to stir for 2 h to obtain a mixed hydrogel.

[0052] S2. After the mixed hydrogel is naturally cooled to room temperature, place it in an environment of -50 °C for vacuum drying treatment for 20 h to obtain a precursor.

[0053] S3. Place the precursor in a tubular furnace filled with N2 atmosphere, heat the temperature to 350 °C at a rate of 2 °C / min, and preheat it at this temperature for 1 h; then continue to heat it to 950 °C at a rate of 10 °C / min, and perform the first pyrolysis at this temperature for 2 h to obtain NiCu dual-atomic porous carbon.

[0054] S4. Immerse the Cu-Ni dual-atomic porous carbon in a 1 mol / L HNO3 solution and perform leaching treatment at 80 °C for 12 h; afterwards, wash it repeatedly with deionized water until it is neutral; then perform filtration treatment with ethanol and dry it to obtain an intermediate.

[0055] S5. Place the intermediate in a tubular furnace filled with N2 atmosphere, heat the temperature to 950 °C at a rate of 5 °C / min, and perform the second pyrolysis at this temperature for 3 h to obtain the carbon-based Cu-Ni dual-atomic catalyst, denoted as Cu / Ni-NC.

[0056] Method 2:

[0057] S1. Weigh 1 g of thiosemicarbazide and transfer it to a three-necked flask containing 40 mL of water. Subsequently, place the three-necked flask in an oil bath, heat it to 55 °C and stir for 20 min. Then, weigh 0.5 g of magnesium chloride hexahydrate, 0.5 g of potassium hydroxide, 0.2 g of nickel acetate and 0.1 g of copper acetate, and add them to the three-necked flask in sequence. Continue to stir at 55 °C for 30 min. Finally, add 0.3 g of chitosan and continue to stir for 4 h to obtain a mixed hydrogel.

[0058] S2. After the mixed hydrogel is naturally cooled to room temperature, place it in an environment of -50 °C for vacuum drying treatment for 20 h to obtain a precursor.

[0059] S3. Place the precursor in a tubular furnace filled with N2 atmosphere, heat the temperature to 350 °C at a rate of 2 °C / min, and preheat it at this temperature for 1 h. Then continue to heat up to 800 °C at a rate of 4 °C / min and carry out the first pyrolysis at this temperature for 3 h to obtain NiCu dual-atom porous carbon.

[0060] S4. Immerse the Cu-Ni dual-atom porous carbon in a 0.5 mol / L HNO3 solution and carry out leaching treatment at 80 °C for 12 h. Then, wash it repeatedly with deionized water until it is neutral. Then carry out filtration treatment with ethanol and drying treatment to obtain an intermediate.

[0061] S5. Place the intermediate in a tubular furnace filled with N2 atmosphere, heat the temperature to 800 °C at a rate of 2 °C / min, and carry out the second pyrolysis at this temperature for 3 h to obtain a carbon-based Cu-Ni dual-atom catalyst.

[0062] Method 3:

[0063] S1. Weigh 3 g of thiosemicarbazide and transfer it to a three-necked flask containing 40 mL of water. Subsequently, place the three-necked flask in an oil bath, heat it to 55 °C and stir for 20 min. Then, weigh 2 g of magnesium chloride hexahydrate, 2 g of potassium hydroxide, 0.6 g of nickel acetate and 0.6 g of copper acetate, and add them to the three-necked flask in sequence. Continue to stir at 95 °C for 30 min. Finally, add 1 g of chitosan and continue to stir for 3 h to obtain a mixed hydrogel.

[0064] S2. After the mixed hydrogel is naturally cooled to room temperature, place it in an environment of -50 °C for vacuum drying treatment for 20 h to obtain a precursor.

[0065] S3. Place the precursor in a tubular furnace filled with N2 atmosphere, heat the temperature to 450 °C at a rate of 5 °C / min, and preheat it at this temperature for 3 h. Then continue to heat up to 1000 °C at a rate of 10 °C / min and carry out the first pyrolysis at this temperature for 1 h to obtain NiCu dual-atom porous carbon.

[0066] S4. Immerse the Cu-Ni dual-atom porous carbon in a 3 mol / L HNO3 solution, and perform leaching treatment at 80 °C for 12 h; then, repeatedly wash with deionized water until neutral; then, perform filtration treatment with ethanol and drying treatment to obtain an intermediate.

[0067] S5. Place the intermediate in a tubular furnace filled with N2 atmosphere, heat the temperature to 1200 °C at a rate of 5 °C / min, and perform the second pyrolysis at this temperature for 1 h to obtain a carbon-based Cu-Ni dual-atom catalyst.

[0068] In order to enable those skilled in the art to more clearly understand the technical solutions of the present disclosure, the technical solutions of the present invention will be described in detail below in combination with specific embodiments. Among them, Cu-Ni-NC in Examples 1 to 8 is prepared by Method 1.

[0069] Example 1

[0070] A preparation method of a carbon-based Cu-Ni dual-atom cluster catalyst includes the following steps:

[0071] Take 5 mg of Cu-Ni-NC and disperse it in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained; then, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, and use this as a working electrode; at the same time, use Ag / AgCl as a reference electrode and a platinum mesh as a counter electrode to jointly assemble a conventional three-electrode system. Inject a 0.5 mol / L CO2-saturated KHCO3 solution into the three-electrode system as an electrolyte; connect the assembled three-electrode system to an electrochemical workstation, and apply a voltage of -1.2 V for in-situ electrolysis treatment for 2 h to obtain a carbon-based Cu-Ni dual-atom cluster catalyst, denoted as -1.2V-Cu7 / Ni-NC; among them, the average number of Cu atoms is 7.

[0072] Example 2

[0073] A preparation method of a carbon-based Cu-Ni dual-atom cluster catalyst includes the following steps:

[0074] Disperse 5 mg of Cu-Ni-NC in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained. Subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, which is used as the working electrode. At the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO₂-saturated KHCO₃ solution into this three-electrode system as the electrolyte. Connect the assembled three-electrode system to an electrochemical workstation and apply a voltage of -1.1 V for in-situ electrolysis treatment for 2 h to obtain a carbon-based Cu-Ni dual-atom cluster catalyst, denoted as -1.1V-Cu / Ni-NC.

[0075] Example 3

[0076] A preparation method of a carbon-based Cu-Ni dual-atom cluster catalyst, comprising the following steps:

[0077] Disperse 5 mg of Cu-Ni-NC in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained. Subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, which is used as the working electrode. At the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO₂-saturated KHCO₃ solution into this three-electrode system as the electrolyte. Connect the assembled three-electrode system to an electrochemical workstation and apply a voltage of -1.0 V for in-situ electrolysis treatment for 2 h to obtain a carbon-based Cu-Ni dual-atom cluster catalyst, denoted as -1.0V-Cu / Ni-NC.

[0078] Example 4

[0079] A preparation method of a carbon-based Cu-Ni dual-atom cluster catalyst, comprising the following steps:

[0080] Disperse 5 mg of Cu-Ni-NC in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained. Subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, which is used as the working electrode. At the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO2-saturated KHCO3 solution into this three-electrode system as the electrolyte. Link the assembled three-electrode system to an electrochemical workstation and apply a voltage of -0.9 V for in-situ electrolysis treatment for 2 h to obtain a carbon-based Cu-Ni dual-atom cluster catalyst, denoted as -0.9V-Cu5 / Ni-NC. Among them, the average number of Cu atoms is 5.

[0081] Example 5

[0082] A preparation method of a carbon-based Cu-Ni dual-atom cluster catalyst, comprising the following steps:

[0083] Disperse 5 mg of Cu-Ni-NC in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained. Subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, which is used as the working electrode. At the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO2-saturated KHCO3 solution into this three-electrode system as the electrolyte. Link the assembled three-electrode system to an electrochemical workstation and apply a voltage of -0.8 V for in-situ electrolysis treatment for 2 h to obtain a carbon-based Cu-Ni dual-atom cluster catalyst, denoted as -0.8V-Cu / Ni-NC.

[0084] Example 6

[0085] A preparation method of a carbon-based Cu-Ni dual-atom cluster catalyst, comprising the following steps:

[0086] Disperse 5 mg of Cu-Ni-NC in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained. Subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, which is used as the working electrode. At the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO₂-saturated KHCO₃ solution into the three-electrode system as the electrolyte. Link the assembled three-electrode system to an electrochemical workstation and apply a voltage of -0.7 V for in-situ electrolysis treatment for 2 h to obtain a carbon-based Cu-Ni dual-atom cluster catalyst, denoted as -0.7V-Cu₃ / Ni-NC; among them, the average number of Cu atoms is 3.

[0087] Example 7

[0088] A preparation method of a carbon-based Cu-Ni dual-atom cluster catalyst, comprising the following steps:

[0089] Disperse 5 mg of Cu-Ni-NC in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained. Subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, which is used as the working electrode. At the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO₂-saturated KHCO₃ solution into the three-electrode system as the electrolyte. Link the assembled three-electrode system to an electrochemical workstation and apply a voltage of -0.6 V for in-situ electrolysis treatment for 2 h to obtain a carbon-based Cu-Ni dual-atom cluster catalyst, denoted as -0.6V-Cu / Ni-NC.

[0090] Example 8

[0091] A preparation method of a carbon-based Cu-Ni dual-atom cluster catalyst, comprising the following steps:

[0092] Disperse 5 mg of Cu-Ni-NC in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained. Subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, which is used as the working electrode. At the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO2-saturated KHCO3 solution into the three-electrode system as the electrolyte. Connect the assembled three-electrode system to an electrochemical workstation and apply a voltage of -0.5 V for in-situ electrolysis treatment for 2 h to obtain a carbon-based Cu-Ni dual-atom cluster catalyst, denoted as -0.5V-Cu / Ni-NC.

[0093] The present invention provides a method for preparing a carbon-based Ni single-atom catalyst, comprising the following steps:

[0094] S1. Weigh 2 g of thiosemicarbazide and transfer it to a three-necked flask containing 40 mL of water. Subsequently, place the three-necked flask in an oil bath, heat it to 55 °C and stir for 20 min. Then, weigh 1.34 g of magnesium chloride hexahydrate, 1.18 g of potassium hydroxide, and 0.4 g of nickel acetate, and add them to the three-necked flask in sequence, and continue to stir at 85 °C for 30 min. Finally, add 0.53 g of chitosan and continue to stir for 2 h to obtain a mixed hydrogel.

[0095] S2. After the mixed hydrogel is naturally cooled to room temperature, place it in an environment of -50 °C for vacuum drying treatment for 20 h to obtain a precursor.

[0096] S3. Place the precursor in a tubular furnace filled with N2 atmosphere, heat the temperature to 350 °C at a rate of 2 °C / min, and preheat it at this temperature for 1 h. Then continue to heat up to 950 °C at a rate of 10 °C / min and carry out the first pyrolysis at this temperature for 2 h to obtain Ni porous carbon.

[0097] S4. Immerse the Ni porous carbon in a 1 mol / L HNO3 solution and carry out leaching treatment at 80 °C for 12 h. Then, wash it repeatedly with deionized water until it is neutral. Then, carry out filtration treatment with ethanol and dry it to obtain an intermediate.

[0098] S5. Place the intermediate in a tubular furnace filled with N2 atmosphere, heat the temperature to 950 °C at a rate of 5 °C / min, and carry out the second pyrolysis at this temperature for 3 h to obtain a carbon-based Ni single-atom catalyst, denoted as Ni-NC.

[0099] Based on the Ni-NC obtained by the above preparation method, taking Ni-NC as an example, in-situ electrolysis treatment is carried out, as specifically shown in Comparative Examples 1 to 8:

[0100] Comparative Example 1

[0101] An in-situ electrolysis treatment method for a carbon-based Ni single-atom catalyst, comprising the following steps:

[0102] Take 5 mg of Ni-NC and disperse it in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained; subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, and use this as the working electrode; at the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO2-saturated KHCO3 solution into this three-electrode system as the electrolyte; connect the assembled three-electrode system to an electrochemical workstation and apply a voltage of -1.2 V for in-situ electrolysis treatment for 2 h.

[0103] Comparative Example 2

[0104] An in-situ electrolysis treatment method for a carbon-based Ni single-atom catalyst, comprising the following steps:

[0105] Take 5 mg of Ni-NC and disperse it in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained; subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, and use this as the working electrode; at the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO2-saturated KHCO3 solution into this three-electrode system as the electrolyte; connect the assembled three-electrode system to an electrochemical workstation and apply a voltage of -1.1 V for in-situ electrolysis treatment for 2 h.

[0106] Comparative Example 3

[0107] An in-situ electrolysis treatment method for a carbon-based Ni single-atom catalyst, comprising the following steps:

[0108] Take 5 mg of Ni-NC and disperse it in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained; subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, and use this as the working electrode; at the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO2-saturated KHCO3 solution into this three-electrode system as the electrolyte; connect the assembled three-electrode system to an electrochemical workstation and apply a voltage of -1.0 V for in-situ electrolysis treatment for 2 h.

[0109] Comparative Example 4

[0110] An in-situ electrolysis treatment method for a carbon-based Ni single-atom catalyst, comprising the following steps:

[0111] Disperse 5 mg of Ni-NC in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained; subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, and use this as the working electrode; at the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO2-saturated KHCO3 solution into this three-electrode system as the electrolyte; link the assembled three-electrode system to an electrochemical workstation and apply a voltage of -0.9 V for in-situ electrolysis treatment for 2 h.

[0112] Comparative Example 5

[0113] An in-situ electrolysis treatment method for a carbon-based Ni single-atom catalyst, comprising the following steps:

[0114] Disperse 5 mg of Ni-NC in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained; subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, and use this as the working electrode; at the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO2-saturated KHCO3 solution into this three-electrode system as the electrolyte; link the assembled three-electrode system to an electrochemical workstation and apply a voltage of -0.8 V for in-situ electrolysis treatment for 2 h.

[0115] Comparative Example 6

[0116] An in-situ electrolysis treatment method for a carbon-based Ni single-atom catalyst, comprising the following steps:

[0117] Disperse 5 mg of Ni-NC in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained; subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, and use this as the working electrode; at the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO2-saturated KHCO3 solution into this three-electrode system as the electrolyte; link the assembled three-electrode system to an electrochemical workstation and apply a voltage of -0.7 V for in-situ electrolysis treatment for 2 h.

[0118] Comparative Example 7

[0119] An in-situ electrolysis treatment method for a carbon-based Ni single-atom catalyst, comprising the following steps:

[0120] Take 5 mg of Ni-NC and disperse it in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained; subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, and use this as the working electrode; at the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO₂-saturated KHCO₃ solution into the three-electrode system as the electrolyte; connect the assembled three-electrode system to an electrochemical workstation and apply a voltage of -0.6 V for in-situ electrolysis treatment for 2 h.

[0121] Comparative Example 8

[0122] An in-situ electrolysis treatment method for a carbon-based Ni single-atom catalyst, comprising the following steps:

[0123] Take 5 mg of Ni-NC and disperse it in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained; subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, and use this as the working electrode; at the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO₂-saturated KHCO₃ solution into the three-electrode system as the electrolyte; connect the assembled three-electrode system to an electrochemical workstation and apply a voltage of -0.5 V for in-situ electrolysis treatment for 2 h.

[0124] The present invention provides a preparation method for a carbon-based Cu single-atom catalyst, comprising the following steps:

[0125] S1. Weigh 2 g of thiosemicarbazide and transfer it to a three-necked flask containing 40 mL of water; subsequently, place the three-necked flask in an oil bath, heat it to 55 °C and stir for 20 min; then, weigh 1.34 g of magnesium chloride hexahydrate, 1.18 g of potassium hydroxide, and 0.32 g of copper acetate, and add them to the three-necked flask in sequence, and continue to stir at 85 °C for 30 min; finally, add 0.53 g of chitosan and continue to stir for 2 h to obtain a mixed hydrogel.

[0126] S2. After the mixed hydrogel is naturally cooled to room temperature, place it in an environment of -50 °C for vacuum drying treatment for 20 h to obtain a precursor.

[0127] S3. Place the precursor in a tubular furnace filled with an N2 atmosphere, heat the temperature to 350 °C at a rate of 2 °C / min, and perform a preheating treatment at this temperature for 1 h; then continue to raise the temperature to 950 °C at a rate of 10 °C / min, and perform the first pyrolysis at this temperature for 2 h to obtain Cu porous carbon.

[0128] S4. Immerse the Cu porous carbon in a 1 mol / L HNO3 solution, and perform a leaching treatment at 80 °C for 12 h; then, repeatedly wash with deionized water until neutral; then perform a filtration treatment with ethanol and a drying treatment to obtain an intermediate.

[0129] S5. Place the intermediate in a tubular furnace filled with an N2 atmosphere, heat the temperature to 950 °C at a rate of 5 °C / min, and perform the second pyrolysis at this temperature for 3 h to obtain a carbon-based Cu single-atom catalyst, denoted as Cu-NC.

[0130] For the Cu-NC obtained based on the above preparation method, taking Cu-NC as an example, perform in-situ electrolysis treatment, specifically as shown in Comparative Examples 9 to 16:

[0131] Comparative Example 9

[0132] An in-situ electrolysis treatment method for a carbon-based Cu single-atom catalyst includes the following steps:

[0133] Take 5 mg of Cu-NC and disperse it in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained; subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, and use this as a working electrode; at the same time, use Ag / AgCl as a reference electrode and a platinum mesh as a counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO2-saturated KHCO3 solution into this three-electrode system as an electrolyte; connect the assembled three-electrode system to an electrochemical workstation and apply a voltage of -1.2 V for in-situ electrolysis treatment for 2 h.

[0134] Comparative Example 10

[0135] An in-situ electrolysis treatment method for a carbon-based Cu single-atom catalyst includes the following steps:

[0136] Disperse 5 mg of Cu-NC in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained. Subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, which is used as the working electrode. At the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO₂-saturated KHCO₃ solution into this three-electrode system as the electrolyte. Link the assembled three-electrode system to an electrochemical workstation and apply a voltage of -1.1 V for in-situ electrolysis treatment for 2 h.

[0137] Comparative Example 11

[0138] An in-situ electrolysis treatment method for a carbon-based Cu single-atom catalyst, comprising the following steps:

[0139] Disperse 5 mg of Cu-NC in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained. Subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, which is used as the working electrode. At the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO₂-saturated KHCO₃ solution into this three-electrode system as the electrolyte. Link the assembled three-electrode system to an electrochemical workstation and apply a voltage of -1.0 V for in-situ electrolysis treatment for 2 h.

[0140] Comparative Example 12

[0141] An in-situ electrolysis treatment method for a carbon-based Cu single-atom catalyst, comprising the following steps:

[0142] Disperse 5 mg of Cu-NC in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained. Subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, which is used as the working electrode. At the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO₂-saturated KHCO₃ solution into this three-electrode system as the electrolyte. Link the assembled three-electrode system to an electrochemical workstation and apply a voltage of -0.9 V for in-situ electrolysis treatment for 2 h.

[0143] Comparative Example 13

[0144] An in-situ electrolysis treatment method for a carbon-based Cu single-atom catalyst, comprising the following steps:

[0145] Disperse 5 mg of Cu-NC in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained. Subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, which is used as the working electrode. At the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Pour 0.5 mol / L of CO₂-saturated KHCO₃ solution into the three-electrode system as the electrolyte. Link the assembled three-electrode system to an electrochemical workstation and apply a voltage of -0.8 V for in-situ electrolysis treatment for 2 h.

[0146] Comparative Example 14

[0147] A method for in-situ electrolysis treatment of a carbon-based Cu single-atom catalyst, comprising the following steps:

[0148] Disperse 5 mg of Cu-NC in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained. Subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, which is used as the working electrode. At the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Pour 0.5 mol / L of CO₂-saturated KHCO₃ solution into the three-electrode system as the electrolyte. Link the assembled three-electrode system to an electrochemical workstation and apply a voltage of -0.7 V for in-situ electrolysis treatment for 2 h.

[0149] Comparative Example 15

[0150] A method for in-situ electrolysis treatment of a carbon-based Cu single-atom catalyst, comprising the following steps:

[0151] Disperse 5 mg of Cu-NC in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained. Subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, which is used as the working electrode. At the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to jointly assemble a conventional three-electrode system. Pour 0.5 mol / L of CO₂-saturated KHCO₃ solution into the three-electrode system as the electrolyte. Link the assembled three-electrode system to an electrochemical workstation and apply a voltage of -0.6 V for in-situ electrolysis treatment for 2 h.

[0152] Comparative Example 16

[0153] A method for in-situ electrolysis treatment of a carbon-based Cu single-atom catalyst, comprising the following steps:

[0154] Disperse 5 mg of Cu-NC in a mixed solution composed of 700 μL of ethanol, 300 μL of water, and 60 μL of Nafion. After ultrasonic treatment for 30 min, a slurry is obtained. Subsequently, take 120 μL of the slurry and evenly coat it on a hydrophobic carbon paper, which is used as the working electrode. At the same time, use Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode to assemble a conventional three-electrode system. Introduce a 0.5 mol / L CO₂-saturated KHCO₃ solution into the three-electrode system as the electrolyte; connect the assembled three-electrode system to an electrochemical workstation and apply a voltage of -0.5 V for in-situ electrolysis treatment for 2 h.

[0155] Observe Figure 1 It is concluded that by testing the crystal structure of the catalyst with an X-ray diffractometer, the results show that the peaks at approximately 22° and 44° belong to the (002) and (100) planes of graphitic carbon with a relatively low degree of crystallinity. This indicates that the prepared carbon-based Cu-Ni dual-atom catalyst has no large metal particles, further demonstrating that these atomic-level sites can be reconstructed into atomic clusters by applying a negative voltage; on the contrary, if large metal particles are formed, the carbon-based Cu-Ni dual-atom catalyst will be very stable and difficult to be further processed into atomic-level clusters.

[0156] Combined with Figure 2 、 Figure 3 and Figure 4 It is concluded that the carbon-based Cu-Ni dual-atom catalyst presents a porous granular morphology, has a rich pore structure, and a relatively low degree of graphitization with many defect structures. Specifically, these defect structures exist in the form of a large number of mesopores and micropores and are accompanied by the distribution of metal sites; further indicating that the carbon-based Cu-Ni dual-atom catalyst is rich in a large number of structural defects and no large metal particles are observed.

[0157] Observe Figure 5 From Figure a in Figure 5 it can be seen that many dual-atom bright spots are evenly distributed on the entire porous carbon skeleton of the carbon-based Cu-Ni dual-atom catalyst. The distance between the dual-atom metals represented by these bright spots is between 0.19 nm and 0.24 nm, as shown in the Figure 5 yellow circle in

[0158] From Figure 5 Figure b in it is concluded that under the condition that the in-situ electrolysis treatment potential is -0.9 V, the Cu-Ni dual-atom sites in the carbon-based Cu-Ni dual-atom catalyst are reconstructed, and metal atoms aggregate, forming a carbon-based Cu-Ni dual-atom cluster catalyst composed of 5 to 7 metal atoms; further, when the voltage is reduced to -1.2 V and reconstruction is carried out, asFigure 5 In Figure c in , the Cu-Ni dual-atom sites in the carbon-based Cu-Ni dual-atom catalyst continue to reconstruct, and the cluster scale is upgraded to form a Cu-Ni dual-atom cluster composed of 8 to 10 metal atoms.

[0159] By comparing Figure 5 Figure b in and Figure c in , it is obtained that the size of the dual-atom cluster of -1.2V-Cu-Ni-NC reconstructed at -1.2V voltage is slightly larger than that of the dual-atom cluster of -0.9V-Cu-Ni-NC reconstructed at -0.9V voltage. Among them, the yellow circle is used to mark the dual-atom pair, the red circle marks the slightly smaller dual-atom cluster, and the blue circle is used to mark the larger cluster.

[0160] Combined with Figure 6 and Figure 7 the data analysis in and , it is obtained that when the in-situ electrolysis treatment potential of Cu-Ni-NC is -0.9V, its selectivity for CO is excellent, up to 96.9%; at the same time, the partial current density of CO at this time is 18 mA / cm 2 , and when the potential is further reduced to -1.2V, the current density of the obtained -1.2V-CuNi-NC increases accordingly, specifically 30 mA / cm 2 .

[0161] Observation Figure 8 shows that the Cu-Ni dual-atom cluster catalyst prepared in Example 4 can stably operate for 120 h at a constant voltage of -0.9V, and during this period, its selectivity for CO does not show an obvious decrease, fully demonstrating that the carbon-based Cu-Ni dual-atom cluster catalyst of the present invention has excellent catalytic stability.

[0162] From Figure 9 Figure a in , it is obtained that as the in-situ electrolysis treatment potential moves negatively, the valence state of the Cu element shows a gradually decreasing trend; while observing Figure 9 Figure b in , it is obtained that as the in-situ electrolysis treatment potential continuously moves negatively, the N coordination number of the Cu element gradually decreases, and at the same time, the metal coordination effect gradually increases, indicating that the Cu metal is gradually aggregating.

[0163] From Figure 10 Figure a in , it is obtained that as the in-situ electrolysis treatment potential moves negatively, the valence state change range of the Ni element is relatively small and remains relatively stable; while observing Figure 10 Figure b in , it is obtained that during the negative movement of the in-situ electrolysis treatment potential, the coordination situation of the Ni element does not change significantly, and only a slight enhancement of the metal peak is observed, indicating that the Ni atoms do not undergo an obvious reconstruction process.

[0164] Combined with Figure 9 andFigure 10 It is concluded that the metal reconstruction phenomenon in the carbon-based Cu-Ni dual-atom catalyst mainly focuses on the Cu element.

[0165] To deeply understand the dynamic reconstruction mechanism of Cu-Ni-NC, in-situ X-ray absorption fine structure technology was used to monitor the changes in the electronic structure and coordination environment of Ni and Cu under the test conditions of electrochemical reduction of carbon dioxide.

[0166] By observing Figure 11 it is obtained that the dynamic evolution process of Cu-Ni-NC is as follows: the initial stage is Cu-S1N3 / Ni-S1N3, as shown in Figure 11 Figure a in Figure 11 ; subsequently, at a potential of -0.7V, its structure transforms into the Ni-S1N3 / Cu3-S1N3 configuration, as shown in Figure 11 Figure b in Figure 11 ; then, when the potential reaches -0.9V, it further evolves into the Ni-S1N3 / Cu5-S1N3 configuration, as shown in

[0167] Figure c in

[0168] ; after that, at a potential of -1.2V, it presents the Ni-S1N3 / Cu7-S1N1 configuration, as shown in Figure 11 Figure d in This series of changes indicates that the preparation method of the present invention can enable Cu-Ni-NC to achieve continuous and orderly structural transformation.

[0167] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0168] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A preparation method of a carbon-based Cu-Ni dual-atom cluster catalyst, characterized in that, The following steps are involved: An aqueous solution of thiosemicarbazide, magnesium chloride hexahydrate, alkali, nickel salt, copper salt and a sugar compound are mixed to obtain a mixed hydrogel, and then freeze-dried to obtain a precursor; The precursor is preheated in an inert atmosphere, and then pyrolyzed for the first time to obtain NiCu diatomic porous carbon, which is then acid-washed to obtain an intermediate; The intermediate is placed in an inert atmosphere for a second pyrolysis to obtain a carbon-based Cu-Ni diatomic catalyst; The carbon-based Cu-Ni diatomic catalyst is prepared into a slurry, adhered to a current collector, and subjected to in-situ electrolysis. During the in-situ electrolysis, Cu ions are reduced to metallic Cu atoms under a negative potential and are separated from the Cu-Ni coordination structure to become Cu-Ni diatomic cluster sites enriched with Cu atoms, thereby obtaining a carbon-based Cu-Ni diatomic cluster catalyst. The conditions for in-situ electrolysis are: in-situ electrolysis at -0.5V~-1.2V for 2h~4h.

2. The preparation method of the carbon-based Cu-Ni dual-atom cluster catalyst according to claim 1, wherein In the mixed hydrogel, the mass ratio of thiosemicarbazide, nickel salt and copper salt is 1~3:0.2~0.6:0.1~0.6, the mass ratio of thiosemicarbazide and sugar compound is 1~3:0.3~1, and the mass ratio of thiosemicarbazide, magnesium chloride hexahydrate and alkali is 1~3:0.5~2:0.5~2.

3. The preparation method of the carbon-based Cu-Ni dual-atom cluster catalyst according to claim 1, wherein, The preheating conditions are: preheating at 350°C~450°C for 1h~3h.

4. The preparation method of the carbon-based Cu-Ni dual-atom cluster catalyst according to claim 1, wherein, The conditions for the first pyrolysis are: pyrolysis at 800°C~1000°C for 1h~3h.

5. The preparation method of the carbon-based Cu-Ni dual-atom cluster catalyst according to claim 1, wherein The conditions for the second pyrolysis are: pyrolysis at 900°C~1200°C for 1h~3h.

6. A carbon-based Cu-Ni dual-atom cluster catalyst, characterized in that, The carbon-based Cu-Ni diatomic cluster catalyst is prepared by the preparation method according to any one of claims 1 to 5.

7. The carbon-based Cu-Ni dual-atom cluster catalyst according to claim 6, wherein The total number of Cu and Ni metal atoms in the carbon-based Cu-Ni diatomic cluster catalyst is 4 to 9.

8. The carbon-based Cu-Ni dual-atom cluster catalyst according to claim 6, wherein, In the carbon-based Cu-Ni diatomic cluster catalyst, the diameter of the Cu-Ni diatomic cluster is less than 2nm.

9. Use of the carbon-based Cu-Ni diatomic cluster catalyst according to claim 6 in preparing a catalyst for electrocatalytic reduction of CO2 to CO.

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