Cu-based single-atom alloy catalyst for electrocatalytic reduction of CO2 and preparation method thereof

Abstract

The present invention belongs to the field of catalyst preparation, and in particular to a Cu-based single-atom alloy catalyst for electrocatalytic reduction of CO2 and a preparation method thereof. The present invention uses Cu with stable performance as a base metal, and utilizes a small molecule organic solvent having both solvent and organic ligand functions to uniformly disperse transition metals in the form of single atoms in a Cu nanocrystalline lattice, forming a single-atom alloy structure with bimetallic active sites, which is more beneficial to the cleavage of the C=C double bond during the electrocatalytic CO2 reduction process, effectively suppresses the HER side reaction, and improves the selective generation efficiency of CO; the present invention uses N,N-dimethylformamide small molecule organic solvent alone as both a solvent and a ligand, and can uniformly disperse transition metal M atoms into a Cu nanocrystalline structure without adding other organic ligands, forming a Cu-based single-atom alloy structure with biactive sites and a heteroatom-modified graphene carrier, thereby achieving the technical effects of simplified operation and reduced cost.

Description

Technical Field

[0001] The present invention belongs to the field of catalyst preparation, and particularly relates to a Cu-based single-atom alloy catalyst for electrocatalytic reduction of CO2 and a preparation method, in particular a preparation method and application of a defective graphene-supported Cu-based single-atom alloy nanocatalyst. Background Art

[0002] Against the backdrop of the rapid development of modern industrialized society, the massive burning of fossil fuels and the excessive emission of pollutants have disrupted the carbon balance of the ecological environment. As one of the major greenhouse gases, CO2 levels are increasing year by year, and the resulting climate effects, such as global warming and rising sea levels, have become a global environmental issue. To prevent the continued escalation of climate and environmental problems, the search for efficient and reliable technologies to recycle atmospheric CO2 and maintain a virtuous cycle between CO2 and renewable chemical energy has become a highly sought-after research topic in the environmental field.

[0003] Electrocatalytic CO2 reduction using renewable electricity is an effective way to convert CO2 to various products, including CO, formic acid, methane, and ethylene. Compared to the production of hydrocarbons through electrocatalytic CO2 reduction, the process for CO reduction is simpler and easier to control, making it more suitable for industrial application. However, the high-reaction-potential cathode electrocatalytic CO2 reduction process is often accompanied by the competing hydrogen evolution reaction (HER), resulting in low product yields and selectivity. Effectively suppressing the HER side reaction and improving product efficiency and selectivity have become important areas of catalyst design and development.

[0004] Bimetallic materials with dual active sites have attracted widespread attention and application in the electrocatalytic reduction of CO2. Among them, single-atom alloy catalysts combine the dual benefits of single-atom and bimetallic catalysis, greatly improving the utilization of metal active sites. Simultaneously, they utilize the electronic synergistic effect of bimetallic coordination structures to enhance the reactivity and selectivity of catalytic CO2 reduction. The Cu nanocrystal structure in transition metal materials possesses a high grain boundary density and defect sites, which can optimize the binding energy of reaction intermediates such as CO. Furthermore, the Cu nanocrystal structure is chemically stable and is often used as a substrate metal to stabilize transition metal single atoms. To increase the stability of metal materials and prevent metal agglomeration and dissolution deactivation, carbon materials are now commonly used as carriers to provide stable support for the metal active components. Introducing heteroatoms (N, O, S, P, etc.) into the carbon material structure to form defect structures not only increases the specific surface area and active sites of the catalytic material, but these defect sites often serve as stable attachment points for metal nanoparticles, thereby constructing an efficient and stable catalytic system.

[0005] At present, the Cu-based bimetallic materials in this field are slightly insufficient in terms of selectivity in the electrocatalytic production of CO2 from CO. At the same time, due to the imperfect preparation method of bimetallic materials, the atoms are easily poorly dispersed on the carbon material, resulting in low catalytic efficiency. Summary of the Invention

[0006] The present invention aims to address the problems of insufficient selectivity in the electrocatalytic reduction of CO to CO, the complex preparation methods of Cu-based alloy catalysts, and the poor dispersion of transition metal atoms. The present invention provides a Cu-based single-atom alloy catalyst for the electrocatalytic reduction of CO and its preparation method. The present invention utilizes stable Cu as the base metal and utilizes a small molecule organic solvent, acting as both a solvent and an organic ligand, to uniformly disperse the transition metal in the form of single atoms within the Cu nanolattice, forming a single-atom alloy structure with bimetallic active sites. This structure is more conducive to the cleavage of the C=C double bond during the electrocatalytic reduction of CO, thereby improving the selective generation efficiency of CO.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention also provides a method for preparing the above-mentioned Cu-based single-atom alloy catalyst, characterized in that it comprises the following steps:

[0009] (1) heating a small molecule organic solvent in a reaction vessel, adding an ion solution containing a transition metal M, heating the reaction at a constant temperature, lowering the temperature to room temperature, and then adding a Cu ion precursor solution to obtain a Cu / M mixed salt solution;

[0010] (2) adding the obtained Cu / M mixed salt solution to the graphene oxide solution, then adding a nitrogen source, ultrasonically mixing, and freeze-drying to obtain a mixed solid powder;

[0011] (3) The mixed solid powder is calcined and reduced at high temperature under the protection of inert gas, and the sample obtained after reduction is filtered, washed, and vacuum dried to obtain a defective graphene-loaded Cu-based single-atom alloy catalytic material.

[0012] Preferably, the small molecule organic solvent in step (1) is one or more of N,N-dimethylformamide (DMF), ethylene glycol, and ethylene glycol monomethyl ether; further preferably, the small molecule organic solvent is DMF.

[0013] Preferably, the transition metal M ion solution in step (1) comprises at least one of chloride, nitrate and sulfate solutions of the transition metal M.

[0014] Preferably, the concentration of the transition metal M ion solution in step (1) is 0.8-1.5 mol / L; further preferably, the concentration of the transition metal M ion solution is 1 mol / L.

[0015] Preferably, the transition metal M in step (1) is a Group VIII metal in the periodic table. Further preferably, the transition metal M includes one or more of Ni, Pd, and Pt.

[0016] Preferably, the Cu ion precursor solution in step (1) includes at least one of copper acetate, copper nitrate, copper chloride and copper sulfate solution; the concentration of the Cu ion precursor solution is 0.02-0.2 mol / L; further preferably, the concentration of the Cu ion precursor solution is 0.04 mol / L.

[0017] Preferably, in step (1), the volume ratio of the small molecule organic solvent to the transition metal M ion solution is (60-300):1; further preferably, the volume ratio of the small molecule organic solvent to the transition metal M ion solution is (80-100):1.

[0018] Preferably, in step (1), the volume ratio of the transition metal M ion solution to the Cu ion precursor solution in step (1) is 1:(1-100); further preferably, the volume ratio of the transition metal M ion solution to the Cu ion precursor solution is 1:(40-60).

[0019] Preferably, the heating temperature in step (1) is 120-150° C., and the reaction time is 8-12 h.

[0020] Preferably, the concentration of the graphene oxide solution in step (2) is 0.5-5 mg / mL, and the amount of the graphene oxide solution used is 50-220 mL.

[0021] Preferably, the nitrogen source in step (2) includes at least one of melamine, urea, aniline, ethylenediamine, and ammonia water.

[0022] Preferably, the mass ratio of melamine to graphene oxide in step (2) is (2-7):1.

[0023] Preferably, the inert gas in step (2) includes at least one of nitrogen, argon and helium.

[0024] Preferably, the high temperature calcination step in step (3) is as follows: first, the temperature is raised from room temperature to 200-400°C at a heating rate of 10°C / min, then raised to 700-900°C at a heating rate of 5°C / min, and maintained at this high temperature for 1.5-3.0h for deep reduction, and then gradually cooled to room temperature.

[0025] In the present invention, the room temperature is 20-25°C.

[0026] Preferably, the washing solvent in step (3) is at least one of deionized water, ethanol or acetone, and the washing times are no less than 3 times.

[0027] The present invention provides a Cu-based single-atom alloy catalyst prepared by the above method, characterized in that the catalyst comprises a carrier graphene and Cu-based single-atom alloy nanoparticles uniformly loaded in the graphene structure; the graphene is defective graphene modified by heteroatom doping; the Cu-based single-atom alloy nanoparticles comprise a base metal Cu and a transition metal M, the transition metal M is stably dispersed in the Cu lattice structure in the form of a single atom, the transition metal M is a Group VIII metal in the periodic table, and the atomic proportions of the base metal Cu and the transition metal M in the catalyst are 0.5-5.0 at.% and 0.1-2.5 at.%, respectively.

[0028] In the present invention, the at.% refers to an "atomic ratio".

[0029] Preferably, the average particle size of the Cu-based single-atom alloy nanoparticles in the catalyst is 1-5 nm.

[0030] Preferably, the transition metal M includes one or more of Pt, Pd, and Ni.

[0031] Preferably, the heteroatoms include N and O.

[0032] Preferably, N accounts for 7-12 at.% of the catalyst, O accounts for 5-10 at.% of the catalyst, and C in graphene oxide accounts for 71-87 at.% of the catalyst.

[0033] Preferably, the molar ratio of Cu to the transition metal M in the catalyst is (1-8):1; further preferably, the molar ratio of Cu to the transition metal M in the catalyst is 2:1.

[0034] Preferably, the maximum Faraday efficiency of the Cu-based single-atom alloy catalyst in electrocatalyzing CO2 to CO is 70-85%.

[0035] The one or more technical solutions provided by the present invention have at least the following technical effects:

[0036] 1. Compared with traditional single-atom catalyst preparation methods, the present invention uses a small molecule organic solvent, especially DMF, as both a solvent and a ligand, without using other organic ligands, to evenly disperse transition metal M atoms into a Cu nanocrystal structure, thereby forming a Cu-based single-atom alloy structure with dual active sites and a heteroatom-modified graphene carrier, thereby achieving the technical effects of simplifying operations and reducing costs.

[0037] 2. The atomically dispersed metal active sites and bimetallic synergistic electronic effect of the present invention improve the electron mass transfer rate and reaction efficiency during the electrocatalytic process, promote the reduction of the CO2 reduction reaction potential, and effectively inhibit the HER side reaction.

[0038] 3. The stable dual active sites in the single-atom alloy structure of the present invention are conducive to the breakage and decomposition of the C=C double bond of the CO2 molecule, further improving the CO generation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 TEM image of the Pt / Cu(111) / N-DG catalyst in Example 1;

[0040] Figure 2 is the STEM image of the Pt / Cu(111) / N-DG catalyst in Example 1;

[0041] Figure 3 is the HAADF-STEM image of the Pt / Cu(111) / N-DG catalyst in Example 1;

[0042] Figure 4 is the XPS spectrum of the Pt / Cu(111) / N-DG catalyst in Example 1;

[0043] Figure 5 is the Faradaic efficiency of the Pt / Cu(111) / N-DG catalyst in Example 1 for electrocatalytic CO2 production of various products;

[0044] Figure 6 TEM image of the Pd / Cu(111) / N-DG catalyst in Example 2;

[0045] Figure 7 HR-TEM image of the Pd / Cu(111) / N-DG catalyst in Example 2;

[0046] Figure 8 is the Faradaic efficiency of the Pd / Cu(111) / N-DG catalyst in Example 2 for electrocatalytic CO2 production of various products;

[0047] Figure 9 TEM image of the Ni / Cu(111) / N-DG catalyst in Example 3;

[0048] Figure 10 HR-TEM image of Ni / Cu(111) / N-DG catalyst in Example 3;

[0049] Figure 11 is the Faradaic efficiency of the Ni / Cu(111) / N-DG catalyst in Example 3 for electrocatalytic CO2 production of various products;

[0050] Figure 12 This is a UV scanning diagram of the change of the complex formed by the organic ligand and the transition metal Pt with time in Comparative Example 1;

[0051] Figure 13 This is a molecular fluorescence image of the complex formed by different organic ligands and transition metal Ni in Comparative Example 2;

[0052] Figure 14 is the Faraday efficiency of the Cu(111) / N-DG catalyst in comparative example 3 for electrocatalytic CO2 production of various products;

[0053] Figure 15 This is the Faraday efficiency of the Ni / Cu(111) / N-DG catalyst with different metal ratios in Comparative Example 4 for electrocatalytic CO2 to CO production. DETAILED DESCRIPTION

[0054] The following is a further description of a Cu-based single-atom alloy catalyst for electrocatalytic reduction of CO2 and its preparation method in conjunction with the accompanying drawings and specific examples.

[0055] Faradaic efficiency testing method: The catalyst was cold-pressed into an electrode (1.0×1.0 mm) and used as the working electrode. Ag / AgCl was used as the reference electrode, and platinum wire was used as the auxiliary electrode. The electrocatalytic reduction of CO₂ performance was tested in a sealed H-type electrolytic cell. Constant-potential electrolysis was performed for 30 minutes within a voltage range of -0.8 to -0.2 V vs. RHE. Both the cathode and anode compartments contained a 0.1 mol / L KHCO₃ solution pre-saturated with CO₂. The CO₂ flow rate in the cathode compartment was 50 mL / min. Products were analyzed and identified by gas chromatography to derive the selectivity and Faradaic efficiency of each product.

[0056] Example 1

[0057] A Cu-based single-atom alloy catalyst for electrocatalytic reduction of CO2 and a preparation method thereof, the preparation method steps are as follows:

[0058] 100 mL of high-purity DMF solution was placed in a 250 mL three-necked round-bottom flask, the silicone oil bath was preheated to 140 ° C, 1 mL of chloroplatinic acid solution (1.0 mol / L, pre-adjusted to pH 7 with hydrochloric acid) was added dropwise, and the reaction was continued at a constant temperature for 10 h under condensation cycle conditions. After the temperature was cooled to 25 ° C, 50 mL of CuCl2 (0.04 mol / L) solution was added dropwise to the flask to obtain a Pt / Cu mixed salt solution; 50 mL of the mixed salt solution was added to 200 mL of graphene oxide solution (1 mg / mL) after ultrasonic dispersion, and the mixture was stirred for 30 min. in, then 1 g of melamine powder was slowly poured into the mixture and ultrasonically dispersed. The resulting mixture was freeze-dried and placed in a crucible, and reduced by high-temperature calcination in a tube furnace under an Ar atmosphere. The high-temperature calcination procedure was as follows: first, the temperature was increased from room temperature to 300 °C at a heating rate of 10 °C / min, then increased to 800 °C at a heating rate of 5 °C / min, and maintained at this high temperature for 1.5 h for deep reduction, and then gradually cooled to 25 °C. The sample obtained after reduction was washed 5 times by deionization centrifugation and freeze-dried to obtain a Pt / Cu(111) / N-DG single-atom alloy catalyst.

[0059] The obtained catalyst includes graphene doped with N and O atoms, base metal Cu and transition metal Pt. The atomic ratio of each element in the catalyst and the average particle size of Cu-based single-atom alloy nanoparticles are shown in Table 1. The TEM, STEM and HAADF-STEM of this catalyst are shown in Table 1. Figure 1 、 2 As shown in Figure 3, the apparent particle size of the Cu-based nanoparticles supported by the reduced graphene is less than 5 nm. Figure 3 Bright spots uniformly distributed in the Cu-based lattice can be observed, indicating that the transition metal Pt is successfully doped into the Cu nanolattice in atomic form and forms Cu-based single-atom alloy nanoparticles. The XPS spectrum of this catalyst is shown in Figure 4 As shown, both the metal elements Cu and Pt contain high valence states, indicating that mutual electron transfer is likely to occur between the two, further verifying the successful introduction and mutual doping of metal Cu and Pt in the graphene structure.

[0060] The Faraday efficiency of various products of electrocatalytic reduction of CO2 by the obtained catalyst was tested. Figure 5 As shown by Figure 5 It can be seen that the highest Faradaic efficiency for CO generation is 83.91%, which is obtained at an applied voltage of −0.6 V (vs. RHE).

[0061] Example 2

[0062] A Cu-based single-atom alloy catalyst for electrocatalytic reduction of CO2 and a preparation method thereof, the preparation method steps are as follows:

[0063] 100 mL of high-purity DMF solution was placed in a 250 mL three-necked round-bottom flask, the silicone oil bath was preheated to 140 ° C, 1 mL of PdCl2 solution (1.0 mol / L, pre-adjusted to pH 7 with hydrochloric acid) was added dropwise, and the reaction was continued at a constant temperature for 10 h under condensation cycle conditions. After the temperature was cooled to room temperature, 50 mL of CuCl2 (0.04 mol / L) solution was added dropwise to the flask to obtain a Pd / Cu mixed salt solution; then the remaining preparation steps in Example 1 were used to obtain a Pd / Cu(111) / N-DG single-atom alloy catalyst. The obtained catalyst includes graphene doped with N and O atoms, base metal Cu and transition metal Pd. The mass fraction of each element in the catalyst and the average particle size of the Cu-based single-atom alloy nanoparticles are shown in Table 1. The TEM and HR-TEM of this catalyst are shown in Table 1. Figure 6 、 7 As shown, Figure 6 This shows that graphene oxide is reduced to graphene sheets with slight wrinkles. Figure 7 It shows that Pd / Cu(111) single-atom alloy is uniformly dispersed in the graphene structure with particles no larger than 5 nm.

[0064] The Faraday efficiencies of various products of electrocatalytic reduction of CO2 by the obtained catalysts are as follows Figure 8 As shown, the highest Faradaic efficiency for CO generation is 74.04%, which is obtained at an applied voltage of −0.6 V (vs. RHE).

[0065] Example 3

[0066] A Cu-based single-atom alloy catalyst for electrocatalytic reduction of CO2 and a preparation method thereof, the preparation method steps are as follows:

[0067] 100 mL of high-purity DMF solution was placed in a 250 mL three-necked round-bottom flask, the silicone oil bath was preheated to 140 ° C, 1 mL of NiCl2 solution (1.0 mol / L) was added dropwise, and the reaction was continued at a constant temperature for 10 h under condensation cycle conditions. After the temperature was cooled to room temperature, 50 mL of CuCl2 (0.04 mol / L) solution was added dropwise to the flask to obtain a Ni / Cu mixed salt solution; then the remaining preparation steps in Example 1 were used to obtain a Ni / Cu(111) / N-DG single-atom alloy catalyst. The obtained catalyst includes graphene modified with N and O atoms, base metal Cu and transition metal Ni. The mass fraction of each element in the catalyst and the average particle size of Cu-based single-atom alloy nanoparticles are shown in Table 1. The TEM and HR-TEM of this catalyst are shown in Table 1. Figure 9 、 10 As shown, it shows that the Ni / Cu(111) single-atom alloy is uniformly dispersed in the slightly wrinkled graphene structure with particles no larger than 5 nm.

[0068] The Faraday efficiencies of various products of electrocatalytic reduction of CO2 by the obtained catalysts are as follows Figure 11 As shown, the highest Faradaic efficiency for CO generation is 83.21%, which is obtained at an applied voltage of −0.5 V (vs. RHE).

[0069] Comparative Example 1

[0070] A Pt / DMF solution in a Cu-based single-atom alloy catalyst preparation process comprises the following steps: placing 100 mL of high-grade pure DMF solution in a 250 mL three-necked round-bottom flask, preheating a silicone oil bath to 140° C., adding 1 mL of chloroplatinic acid solution (1.0 mol / L, pre-adjusted to pH 7 with hydrochloric acid) dropwise, heating at a constant temperature for 12 h under condensation cycle conditions, and then lowering the temperature to 25° C. to obtain a Pt / DMF solution; the UV scanning spectrum of the obtained Pt / DMF solution is as follows: Figure 12 As shown in the figure, as the reaction time increases, the coordination effect between DMF and metal ions gradually increases. However, when the reaction time exceeds 10 hours, the coordination effect is not obvious. Therefore, a heating reaction time of 10 hours can obtain a transition metal M / DMF solution with the best dispersion effect.

[0071] Comparative Example 2

[0072] The reaction of transition metal Ni salt in different small molecule organic solvents during the preparation of Cu-based single-atom alloy catalysts, the reaction steps are as follows: small molecule organic solvents ethylene glycol, ethylene glycol monomethyl ether, and DMF with coordination effect are respectively used as solvents, 100 mL of small molecule organic solvent is placed in a 250 mL three-necked round-bottom flask, silicone oil bath is preheated (ethylene glycol and DMF heating temperature are both 140 ° C, ethylene glycol monomethyl ether heating temperature is 120 ° C), 1 mL of NiCl2 solution (1.0 mol / L) is added dropwise, and the reaction is continuously heated at a constant temperature for 12 hours under condensation cycle conditions to obtain Ni salt test solutions, which are marked as Ni + ethylene glycol, Ni + ethylene glycol monomethyl ether, and Ni + DMF respectively; molecular fluorescence analysis of the obtained Ni salt test solution and high-purity DMF is performed, and the following is obtained. Figure 13 As shown in the molecular fluorescence spectrum, Ni+ethylene glycol does not show obvious excitation waves in the ultraviolet light band. In contrast, the Ni salt test solution obtained using DMF has the most obvious peak under ultraviolet light excitation, indicating that DMF has a strong light coordination effect on Ni ions. Using DMF as an organic solvent can better disperse the transition metal atoms in the catalyst.

[0073] Comparative Example 3

[0074] A method for preparing a Cu-based catalyst for electrocatalytic reduction of CO2 comprises the following steps: pipetting 100 mL of high-grade pure DMF and dropwise adding 50 mL of a CuCl2 (0.04 mol / L) solution to obtain a Cu salt solution; adding 50 mL of the Cu salt solution to 200 mL of an ultrasonically dispersed graphene oxide solution (1 mg / mL), stirring continuously for 30 minutes, then slowly pouring 1 g of melamine powder into the mixed solution and ultrasonically dispersing the solution; and freeze-drying the resulting mixed solution and placing it in a crucible. The sample was then calcined and reduced at high temperature in a tubular furnace under an Ar atmosphere. The calcination procedure was as follows: first, the temperature was raised from room temperature to 300°C at a heating rate of 10°C / min, then raised to 800°C at a heating rate of 5°C / min, and maintained at this high temperature for 1.5 h for deep reduction, and then gradually cooled to room temperature. The sample obtained after reduction was washed 5 times by deionization centrifugation and freeze-dried to obtain a Cu(111) / N-DG catalyst. The Faraday efficiency of the various products of the electrocatalytic reduction of CO2 by the obtained catalyst is shown in FIG. Figure 14 As shown, the highest Faradaic efficiency for CO production is 63.21%, achieved at an applied voltage of -0.7 V (vs. RHE). The catalyst's selectivity for CO is significantly weaker than that of Cu-based single-atom alloy catalysts doped with transition metals M (Pt, Pd, Ni), indicating that the doping of single-atom transition metals effectively improves the catalyst's selectivity for reducing CO2 to CO.

[0075] Comparative Example 4

[0076] A method for preparing a Cu-based single-atom alloy catalyst for electrocatalytic reduction of CO2, referring to the preparation method of Example 3, wherein the total molar amount of the added transition metal (0.6 mmol) is maintained unchanged, and the molar ratio of the transition metal Ni to Cu is changed to 1:1, 1:2 (same as Example 3), 1:3, and 1:4, respectively. The Faradaic efficiency of the electrocatalytic reduction of CO2 to CO produced by the obtained catalyst is as follows: Figure 15 As shown in FIG, when Ni:Cu=1:2, the selectivity for CO is the best.

[0077] In summary, it can be seen from the Faraday efficiency diagrams of Examples 1, 2, 3 and Comparative Examples 3 and 4 that the Pt / Cu(111) / N-DG single-atom alloy catalyst prepared under the conditions of Example 1 has better CO selectivity. DMF serves as both a solvent and an organic ligand, which can make the transition metal M (Pt, Pd, Ni) more evenly dispersed in the Cu nanolattice, greatly improving the reaction activity and selectivity of the catalyst for electrocatalytic CO2 to CO.

[0078] Table 1. Elemental composition and average particle size of the catalysts in Examples 1-3

[0079]

Claims

1. A method for preparing a Cu-based single-atom alloy catalyst for electrocatalytic reduction of CO2, characterized in that: The following steps are involved: (1) Heat the small molecule organic solvent DMF to 120-150°C, add the transition metal M ion solution, react at constant temperature for 8-12 hours, cool to room temperature, and then add the Cu ion precursor solution to obtain a Cu / M mixed salt solution; (2) Adding the Cu / M mixed salt solution to the graphene oxide solution, followed by adding a nitrogen source, ultrasonically mixing, and freeze-drying to obtain a mixed solid powder; (3) calcining and reducing the mixed solid powder under the protection of inert gas at high temperature, washing, filtering and vacuum drying the obtained sample after reduction to obtain a defective graphene-supported Cu-based single-atom alloy catalytic material; Wherein, the concentration of the transition metal M ion solution in step (1) is 0.8-1.5 mol / L, the transition metal M includes one or more of Ni, Pd, and Pt, the volume ratio of the small molecule organic solvent DMF to the transition metal M ion solution is (60-300):1, the concentration of the Cu ion precursor solution is 0.02-0.2 mol / L, and the volume ratio of the transition metal M ion solution to the Cu ion precursor solution is 1:(1-100); the concentration of the graphene oxide solution in step (2) is 0.5-5 mg / mL, and the amount of the graphene oxide solution is 50-220 mL; the high temperature calcination step in step (3) is as follows: first, the temperature is increased from room temperature to 200-400°C at a heating rate of 10°C / min, and then the temperature is increased to 700-900°C at a heating rate of 5°C / min, and the temperature is maintained at this high temperature for 1.5-3.0 h for deep reduction, and then gradually cooled to 20-25° C.; the molar ratio of Cu to transition metal M in the catalyst is (1-2):

1.

2. The preparation method according to claim 1, characterized in that The transition metal M ion solution in step (1) includes at least one of a chloride, nitrate, and sulfate solution of the transition metal M; and the Cu ion precursor solution in step (1) is at least one of a copper acetate, copper nitrate, copper chloride, and copper sulfate solution.

3. The preparation method according to claim 1, characterized in that In step (1), the volume ratio of the small molecule organic solvent DMF to the transition metal M ion solution is (80-100):

1.

4. The preparation method according to claim 1, characterized in that In step (1), the volume ratio of the transition metal M ion solution to the Cu ion precursor solution is 1:(40-60).

5. The preparation method according to claim 1, characterized in that The nitrogen source in step (2) includes at least one of melamine, urea, aniline, ethylenediamine, and ammonia water.

6. The preparation method according to claim 5, characterized in that The nitrogen source is melamine, and the mass ratio of melamine to graphene oxide is (2-7):

1.

7. The preparation method according to claim 1, characterized in that In step (3), the inert gas includes nitrogen, argon, and helium; the washing solvent is at least one of deionized water, ethanol, and acetone, and the washing times are no less than 3 times.

8. The Cu-based single-atom alloy catalyst prepared by the method according to any one of claims 1 to 7, characterized in that: The catalyst includes a carrier graphene and Cu-based single-atom alloy nanoparticles uniformly loaded in the graphene structure; the graphene is heteroatom-modified graphene; the Cu-based single-atom alloy nanoparticles include a base metal Cu and a transition metal M, wherein the transition metal M is stably doped in the Cu lattice structure in the form of a single atom; the atomic proportions of Cu and the transition metal M in the catalyst are 0.5-5.0 at.% and 0.1-2.5 at.%, respectively; the average particle size of the Cu-based single-atom alloy nanoparticles is 1-5 nm; the heteroatoms include N and O, wherein N accounts for 7-12 at.% of the catalyst and O accounts for 5-10 at.%.

9. The Cu-based single-atom alloy catalyst according to claim 8, characterized in that The Cu-based single-atom alloy catalyst electrocatalyzes CO2 to produce CO with a maximum Faradaic efficiency of 70-85%.

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