A plasma-enhanced single-atom catalyst for electrocatalytic reduction of CO 2 Methods

Abstract

The present invention discloses a method for realizing electrocatalytic reduction of CO2 by a plasma-enhanced single-atom catalyst. The present invention adopts a high-temperature pyrolysis method, selects hierarchically porous nitrogen-doped carbon as the carbon carrier, and selects nickel nitrate hexahydrate, glucose, and melamine as the precursors to synthesize a highly dispersed Ni single-atom catalyst anchored on the hierarchically porous nitrogen-doped carbon, which is used as an electrocatalyst for highly efficient electrocatalytic reduction of CO2. The present invention uses low-temperature plasma treatment of carbon paper to modify the electrocatalyst-substrate interface, enhance the charge transfer process during the electroreduction process, and combine the excellent CO2 electroreduction performance of the single-atom catalyst to further increase the partial current density of CO.

Description

Technical Field

[0001] The present invention belongs to the technical field of electro-reduction conversion and energy storage, and in particular relates to a method for realizing electro-catalytic reduction of CO2 using plasma-enhanced single-atom catalysts. Background Art

[0002] In recent years, the large-scale use of fossil energy such as coal, oil, and natural gas has led to a rapid increase in the concentration of CO2 in the atmosphere, which in turn has caused the greenhouse effect, sea level rise, ocean acidification, and extreme weather in some local areas, seriously threatening human survival.

[0003] Among the many CO2 disposal methods, CO2 synthesis chemical technology can be deeply integrated with energy, chemical and other processes, directly using CO2 to prepare basic chemical raw materials with high added value (such as CO, methanol, ethylene, etc.), to achieve the reduction or replacement of traditional high-carbon raw materials, reduce the consumption of fossil fuels, and have great potential for comprehensive emission reduction. Among the many CO2 chemical synthesis and utilization technologies, CO2 electrocatalytic reduction technology has simple equipment and flexible and convenient reactions, which can effectively absorb and utilize low-grade renewable energy, realize the conversion of carbon dioxide into green chemicals or fuels at normal temperature and pressure, and solve the problems of uneven temporal and spatial distribution of renewable energy such as wind and light and the safety of large-scale grid connection.

[0004] At present, the main research focus of domestic and foreign universities and research institutions on the electrocatalytic reduction of CO2 to CO is mainly on the material development of electrode catalysts (including precious metals, transition metals and metal-loaded carbon materials, etc.). Precious metal catalysts mainly include Au, Ag, and Pt, which have strong conductivity and high CO selectivity, but the high price of precious metals is not suitable for large-scale production. In recent years, the development of "single atom catalysts" with isolated transition metal atoms as active sites dispersed on carbon carriers has the characteristics of "unsaturated coordination environment" and "100% metal atom utilization", which are widely used in the CO2 electroreduction process. It is reported that carbon carriers with high specific surface area and rich hierarchical pore structure can promote CO2 diffusion, and carbon carriers with high nitrogen doping content are conducive to anchoring metal ions through nitrogen elements to avoid metal aggregation. In addition to directly designing SACs electrocatalysts, the optimization of the electrocatalyst-substrate interface also has a close impact on the overall reaction performance. Non-thermal plasma (NTP) has the advantages of relatively low processing temperature and rich active substances, and has been widely used in material modification. Research has shown that using different atmospheres to treat materials through plasma can change surface wettability, increase defect sites, improve surface roughness, and thereby reduce the thermodynamic energy barrier of the reaction.

[0005] The Faradaic efficiency of the single-atom catalysts currently studied for the electrocatalytic reduction of CO2 to CO is mostly only 90%, the selectivity for CO needs to be improved, and the current of the reaction in the H-type electrolytic cell is relatively low; the preparation method of the carbon carriers supported by most single-atom catalysts is relatively complicated, the process cost is high, and it is not suitable for industrial applications.

[0006] Therefore, we designed a highly dispersed Ni single-atom catalyst with nitrogen-doped porous carbon as the carrier for the electrocatalytic reduction of CO2 to CO, and further modified the electrocatalyst-substrate interface by plasma treatment of carbon paper to enhance the charge transfer process during the electroreduction process, thereby achieving efficient CO2 to CO conversion under mild conditions. Summary of the invention

[0007] The purpose of the present invention is to propose a method for preparing a Ni single atom catalyst highly dispersed on nitrogen-doped graded porous carbon, a method for modifying the electrocatalyst-substrate interface by plasma treatment of carbon paper, and a technology for improving the hydrophilicity of the material and strengthening the charge transfer process based on the existing electrocatalytic CO2 conversion technology, so as to maximize the utilization of Ni metal atoms and achieve a CO selectivity of up to 98%, thereby solving the problems of low CO current density, low selectivity, and high overall cost in the existing electrocatalytic CO2 conversion to CO process.

[0008] The object of the present invention is achieved through the following technical solution: a method for realizing electrocatalytic reduction of CO2 by plasma-enhanced single-atom catalyst, the method comprising the following steps:

[0009] (1) Place the carbon paper material vertically into a quartz tube, evacuate it, and then introduce argon gas so that the tube contains argon gas and is in a vacuum state;

[0010] (2) treating the carbon paper material with plasma by an inductively coupled plasma device to form Ar plasma etching on the carbon paper surface;

[0011] (3) mixing the Ni single atom catalyst, isopropanol and Nafion solution and then sonicating;

[0012] (4) The solution obtained in step (3) is sprayed onto the surface of the Ar plasma etched carbon paper by a spray gun to serve as the working electrode of the H-type electrolytic cell.

[0013] (5) The H-type electrolytic cell was separated by a proton exchange membrane, and a Pt sheet was used as a counter electrode of the H-type electrolytic cell. 50 ml of a 0.1 mol / L potassium bicarbonate solution was added to both sides of the H-type electrolytic cell as an electrolyte. Carbon dioxide was introduced as a reaction gas through a mass flow meter to the working electrode side of the H-type electrolytic cell at a flow rate of 30 sccm for at least 30 min to obtain a potassium bicarbonate electrolyte saturated with carbon dioxide.

[0014] (6) After the carbon dioxide gas is saturated, the electrochemical workstation is turned on and the catalyst is activated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) methods. Different voltages are applied through the electrochemical workstation to perform a 60-min constant potential electrochemical catalytic reaction and collect the electrolyte on the working electrode side of the H-type electrolytic cell.

[0015] Furthermore, the preparation process of the Ni single atom catalyst includes the following steps:

[0016] (1) 12 g of glucose, 0.87 g of nickel nitrate hexahydrate, 0.6 g of porous nitrogen-doped carbon, and 50 ml of deionized water were mixed and ultrasonicated for 1 h.

[0017] (2) The mixture prepared in step (1) was centrifuged at 8000 rpm for 5 min, and the solid matter was collected and placed in a drying oven to dry at 80° C. overnight.

[0018] (3) The solid powder prepared in step (2) is uniformly mixed with melamine in a mass ratio of 1:5, placed in a tubular furnace, and heated to 800°C at a rate of 10°C / min in an atmosphere of N2 flow rate of 20 sccm, maintained for 2 hours, and cooled to room temperature to obtain a highly dispersed porous nitrogen-doped carbon-supported Ni single atom catalyst.

[0019] Furthermore, in step (2), the power of the inductively coupled plasma equipment is set to 100 W and the time is 5 minutes.

[0020] Furthermore, in step (4), the loading amount of Ni single atoms on the Ar plasma etched carbon paper is 1 mg / cm 2 .

[0021] Furthermore, a reaction of reducing CO2 to CO occurs at the cathode, and a reaction of oxidizing H2O to oxygen occurs at the anode.

[0022] Furthermore, the outlet gas on the working electrode side of the H-type electrolytic cell is introduced into a gas chromatograph, and the concentration of the gas product CO is detected by the gas chromatograph.

[0023] Furthermore, 500 μl of the cathode electrolyte after the reaction was taken, 100 μl of deuterated DMSO solution was added, and the solution was tested by nuclear magnetic resonance, which proved that no liquid phase product was generated.

[0024] Beneficial effects of the present invention:

[0025] (1) The present invention prepares a highly dispersed single-atom catalyst Ni-SACs / NHPC by using hierarchical porous nitrogen-doped carbon as a carbon carrier, which has high efficiency in electrocatalytic reduction of CO2.

[0026] (2) The present invention uses low-temperature plasma to treat carbon paper to modify the electrocatalyst-substrate interface, enhance the charge transfer process during the electroreduction process, and improve the electrocatalytic reduction activity of CO2.

[0027] (3) The catalyst substrate is carbon material, which is inexpensive, environmentally friendly, and suitable for industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is the XRD spectrum of Ni single atom catalyst Ni-SACs / NHPC in Example 1-4;

[0029] Figure 2 is the N1s spectrum of the Ni single atom catalyst Ni-SACs / NHPC in Example 1-4;

[0030] Figure 3 is a SEM image of the Ni single atom catalyst Ni-SACs / NHPC in Examples 1-4;

[0031] Figure 4 is the HAADF-STEM image of the Ni single atom catalyst Ni-SACs / NHPC in Example 1-4;

[0032] Figure 5 is the EDS image of the Ni single atom catalyst Ni-SACs / NHPC in Example 1-4;

[0033] Figure 6 Graphs showing contact angles of carbon paper not treated with plasma in Example 1 (a) and carbon paper treated with plasma at 100 W in Example 3 (b).

[0034] Figure 7 These are AFM images of the carbon paper that was not plasma treated in Example 1 (a) and the carbon paper that was treated with a plasma power of 100 W in Example 3 (b).

[0035] Figure 8 is a Faraday efficiency diagram of the catalysts in Examples 1-4 at different voltages;

[0036] Fig. 9 Graph showing the CO current density of the catalysts in Examples 1-4 at different voltages. DETAILED DESCRIPTION

[0037] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0038] Example 1

[0039] The preparation method of the carbon-based single-atom catalyst Ni-SACs / NHPC for electrocatalytic reduction of CO2 to generate CO in this embodiment comprises the following steps:

[0040] 1. Preparation of Ni single atom catalyst Ni-SACs / NHPC

[0041] (1) 12 g of glucose, 0.87 g of nickel nitrate hexahydrate, 0.6 g of porous nitrogen-doped carbon, and 50 ml of deionized water were mixed and ultrasonicated for 1 h.

[0042] (2) The mixture prepared in step (1) was centrifuged at 8000 rpm for 5 min, and the solid matter was collected and placed in a drying oven to dry at 80° C. overnight.

[0043] (3) The solid powder prepared in step (2) is uniformly mixed with melamine in a mass ratio of 1:5, placed in a tube furnace, and heated to 800°C at a rate of 10°C / min in an atmosphere of N2 flow rate of 20 sccm, and maintained for 2 h to obtain a Ni single atom catalyst Ni-SACs / NHPC highly dispersed on porous nitrogen-doped carbon.

[0044] (4) XRD and XPS characterization of the catalyst Ni-SACs / NHPC. XRD spectrum ( Figure 1 ) have diffraction peaks at 24.0° and 44.2°, corresponding to typical carbon (002) and (100) planes, and no Ni crystals appear, indicating that there are no Ni metal clusters in the catalyst. The N1s spectrum of the catalyst characterized by XPS ( Figure 2 ), the structures of pyridinic-nitrogen (~399.08eV), pyrrolic-nitrogen (~400.84eV), graphitic-nitrogen (~401.73eV) and oxidized-nitrogen (~404eV) were observed, among which the content of pyridinic-nitrogen (47.16%) was higher than that of pyrrolic-nitrogen (25.11%), graphitic-nitrogen (17.73%) and oxidized-nitrogen (10.0%), indicating that a favorable Ni-N bond (pyrrolic-nitrogen) was formed in the catalyst Ni-SACs / NHPC.

[0045] (5) Figure 3 SEM images show that the catalyst Ni-SACs / NHPC has a three-dimensional hierarchical interconnected pore structure. Figure 4 The magnified HAADF-STEM image shows that Ni single atoms are dispersed on the self-supporting framework of hierarchical porous carbon. Figure 4 Isolated Ni atoms are identified as bright spots in (c). Figure 5 The EDS image in the middle shows that Ni, N, C, and O are evenly distributed on the entire electrocatalyst surface without obvious aggregation of Ni metal atoms.

[0046] 2. Working Electrode Preparation

[0047] (1) Take 10 mg of Ni single atom catalyst, mix it with 1850 μL of isopropanol and sonicate it for 0.5 h, then add 50 μL of Nafion solution, mix it and sonicate it for 1 h.

[0048] (2) Take 285 μL of the mixed solution and spray it on an untreated carbon paper (area 1 cm*1 cm) using a spray gun to serve as the working electrode Ni-SACs / NHPC of the H-type electrolytic cell.

[0049] 3. Electrochemical testing

[0050] (1) The H-type electrolytic cell was separated by a proton exchange membrane, and a Pt sheet was used as the counter electrode of the H-type electrolytic cell. 50 ml of a 0.1 mol / L potassium bicarbonate solution was added to both sides as an electrolyte. Carbon dioxide was passed as a reaction gas through a mass flow meter to the working electrode side of the H-type electrolytic cell at a flow rate of 30 sccm for at least 30 min to obtain a potassium bicarbonate electrolyte saturated with carbon dioxide.

[0051] (2) After the carbon dioxide gas is saturated, the electrochemical workstation is turned on and the catalyst is activated by the CV and LSV methods. Different voltages (-1.14V, -1.24V, -1.34V, -1.44V, -1.54V, -1.64V, -1.74V, -1.84V) are applied through the electrochemical workstation to carry out a 60-min constant potential electrochemical catalytic reaction. The outlet gas on the working electrode side of the H-type electrolytic cell is introduced into a gas chromatograph.

[0052] Example 2

[0053] The plasma-promoted hierarchical porous carbon-supported Ni single-atom catalyst of this embodiment is used in the method for electrocatalytic reduction of CO2, and the steps are as follows:

[0054] 1. Ni single atom catalyst Ni-SACs / NHPC was prepared according to step 1 of Example 1.

[0055] 2. Low temperature plasma treatment of carbon paper for electrocatalyst-substrate interface modification

[0056] (1) Place the carbon paper material vertically into a quartz tube, evacuate it, and then introduce argon gas so that the tube contains argon gas and is in a vacuum state;

[0057] (2) Turn on the inductively coupled plasma equipment, set the power to 50 W, and the time to 5 min to form Ar plasma to etch the surface of the carbon paper for loading the catalyst.

[0058] 3. Electrochemical testing

[0059] (1) Take 10 mg of Ni single atom catalyst, mix it with 1850 μL of isopropanol and sonicate it for 0.5 h, then add 50 μL of Nafion solution, mix it and sonicate it for 1 h.

[0060] (2) Take 285 μL of the mixed solution and spray it on the carbon paper treated in step 2. (3) (area 1 cm*1 cm) using a spray gun to serve as the working electrode Ni-SACs / NHPC of the H-type electrolytic cell. 50 .

[0061] (3) The H-type electrolytic cell was separated by a proton exchange membrane, and a Pt sheet was used as the counter electrode of the H-type electrolytic cell. 50 ml of a 0.1 mol / L potassium bicarbonate solution was added to both sides as an electrolyte. Carbon dioxide was passed as a reaction gas through a mass flow meter to the working electrode side of the H-type electrolytic cell at a flow rate of 30 sccm for at least 30 min to obtain a potassium bicarbonate electrolyte saturated with carbon dioxide.

[0062] (4) After the carbon dioxide gas is saturated, the electrochemical workstation is turned on and the catalyst is activated by the CV and LSV methods. Different voltages (-1.14V, -1.24V, -1.34V, -1.44V, -1.54V, -1.64V, -1.74V, -1.84V) are applied through the electrochemical workstation to carry out a 60-min constant potential electrochemical catalytic reaction. The outlet gas on the working electrode side of the H-type electrolytic cell is introduced into a gas chromatograph.

[0063] Example 3

[0064] The plasma-promoted hierarchical porous carbon-supported Ni single-atom catalyst of this embodiment is used in the method for electrocatalytic reduction of CO2, and the steps are as follows:

[0065] 1. Ni single atom catalyst Ni-SACs / NHPC was prepared according to step 1 of Example 1.

[0066] 2. Low temperature plasma treatment of carbon paper for electrocatalyst-substrate interface modification

[0067] (1) Place the carbon paper material vertically into a quartz tube, evacuate it, and then introduce argon gas so that the tube contains argon gas and is in a vacuum state;

[0068] (2) Turn on the inductively coupled plasma device, set the power to 100 W, and the time to 5 min to form Ar plasma to etch the carbon paper surface for loading the catalyst.

[0069] 3. Electrochemical testing

[0070] (1) Take 10 mg of Ni single atom catalyst, mix it with 1850 μL of isopropanol and sonicate it for 0.5 h, then add 50 μL of Nafion solution, mix it and sonicate it for 1 h.

[0071] (2) Take 285 μL of the mixed solution and spray it on the carbon paper treated in step 2. (3) (area 1 cm*1 cm) using a spray gun to serve as the working electrode Ni-SACs / NHPC of the H-type electrolytic cell. 100 .

[0072] (3) The H-type electrolytic cell was separated by a proton exchange membrane, and a Pt sheet was used as the counter electrode of the H-type electrolytic cell. 50 ml of a 0.1 mol / L potassium bicarbonate solution was added to both sides as an electrolyte. Carbon dioxide was passed as a reaction gas through a mass flow meter to the working electrode side of the H-type electrolytic cell at a flow rate of 30 sccm for at least 30 min to obtain a potassium bicarbonate electrolyte saturated with carbon dioxide.

[0073] (4) After the carbon dioxide gas is saturated, the electrochemical workstation is turned on and the catalyst is activated by the CV and LSV methods. Different voltages (-1.14V, -1.24V, -1.34V, -1.44V, -1.54V, -1.64V, -1.74V, -1.84V) are applied through the electrochemical workstation to carry out a 60-min constant potential electrochemical catalytic reaction. The outlet gas on the working electrode side of the H-type electrolytic cell is introduced into a gas chromatograph.

[0074] Example 4

[0075] The plasma-promoted hierarchical porous carbon-supported Ni single-atom catalyst of this embodiment is used in the method for electrocatalytic reduction of CO2, and the steps are as follows:

[0076] 1. Ni single atom catalyst Ni-SACs / NHPC was prepared according to step 1 of Example 1.

[0077] 2. Low temperature plasma treatment of carbon paper for electrocatalyst-substrate interface modification

[0078] (1) Place the carbon paper material vertically into a quartz tube, evacuate it, and then introduce argon gas so that the tube contains argon gas and is in a vacuum state;

[0079] (2) Turn on the inductively coupled plasma equipment, set the power to 150 W, and the time to 5 min to form Ar plasma to etch the carbon paper surface for loading the catalyst.

[0080] 3. Electrochemical testing

[0081] (1) Take 10 mg of Ni single atom catalyst, mix it with 1850 μL of isopropanol and sonicate it for 0.5 h, then add 50 μL of Nafion solution, mix it and sonicate it for 1 h.

[0082] (2) Take 285 μL of the mixed solution and spray it on the carbon paper treated in step 2. (3) (area 1 cm*1 cm) using a spray gun to serve as the working electrode Ni-SACs / NHPC of the H-type electrolytic cell. 150 .

[0083] (3) The H-type electrolytic cell was separated by a proton exchange membrane, and a Pt sheet was used as the counter electrode of the H-type electrolytic cell. 50 ml of a 0.1 mol / L potassium bicarbonate solution was added to both sides as an electrolyte. Carbon dioxide was passed as a reaction gas through a mass flow meter to the working electrode side of the H-type electrolytic cell at a flow rate of 30 sccm for at least 30 min to obtain a potassium bicarbonate electrolyte saturated with carbon dioxide.

[0084] (4) After the carbon dioxide gas is saturated, the electrochemical workstation is turned on and the catalyst is activated by the CV and LSV methods. Different voltages (-1.14V, -1.24V, -1.34V, -1.44V, -1.54V, -1.64V, -1.74V, -1.84V) are applied through the electrochemical workstation to carry out a 60-min constant potential electrochemical catalytic reaction. The outlet gas on the working electrode side of the H-type electrolytic cell is introduced into a gas chromatograph.

[0085] The specific surface area and pore volume of the catalyst were measured using a specific surface area / pore analyzer, as shown in Table 1.

[0086] Table 1

[0087] catalyst <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[Micropore specific surface area (m 2 / g)]]> <![CDATA[Total pore volume (cm 3 / g)]]> NHPC 2115.7 1581.3 1.08 Ni-SACs / NHPC 1115.6 1001.3 0.643

[0088] The content of Ni and N elements in the catalyst surface layer was tested using an X-ray photoelectron spectrometer, and the content of Ni element in the catalyst was tested using an element analyzer. The test results are shown in Table 2.

[0089] Table 2

[0090]

[0091] Experimental results: The selectivity of the material in Example 1 for CO is as high as 97.67% at a voltage of -1.54V (-0.94V vs. RHE) ( Figure 8 ), CO current density is 10.62 mA / cm 2 ( Fig. 9 ); The selectivity of the material in Example 2 for CO is as high as 92.94% at a voltage of -1.54V (-0.94V vs. RHE) ( Figure 8 ), CO current density is 11.3 mA / cm 2 ( Fig. 9 ); The selectivity of the material in Example 3 for CO is as high as 96.15% at a voltage of -1.54V (-0.94V vs.RHE) ( Figure 8 ), CO current density is 12.3 mA / cm 2 ( Fig. 9 ); The selectivity of the material in Example 4 for CO is as high as 87.68% at a voltage of -1.54V (-0.94V vs.RHE) ( Figure 8 ), CO current density is 13.4 mA / cm 2 ( Fig. 9 ); Compared with the material of Example 1 and the material of Example 3, the surface of the carbon paper becomes more hydrophilic ( Figure 6 ), the surface roughness increases ( Figure 7 ).

[0092] Comprehensive evaluation of CO selectivity and CO current density, the material Ni-SACs / NHPC of Example 3 100 The best choice.

[0093] The above embodiments are used to illustrate the present invention rather than to limit the present invention. Any modification and change made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A method for electrocatalytic reduction of CO2 using plasma-enhanced single-atom catalysts, characterized in that: The method comprises the following steps: (1) Place the carbon paper material vertically into a quartz tube, evacuate it, and then introduce argon gas so that the tube contains argon gas and is in a vacuum state; (2) Plasma treatment of the carbon paper material is performed by an inductively coupled plasma device to form Ar plasma etching of the carbon paper surface; (3) Mixing the Ni single atom catalyst, isopropanol and Nafion solution and subjecting them to ultrasound; the preparation process of the Ni single atom catalyst includes the following steps: (3.1) Mix 12 g glucose, 0.87 g nickel nitrate hexahydrate, 0.6 g porous nitrogen-doped carbon and 50 ml deionized water and sonicate for 1 h. (3.2) centrifuging the mixture prepared in step (3.1) at 8000 rpm for 5 min, collecting the solid matter, placing it in a drying oven and drying it at 80° C. overnight; (3.3) The solid powder prepared in step (3.2) was uniformly mixed with melamine at a mass ratio of 1:5, placed in a tube furnace, heated to 800°C at a rate of 10°C / min in an atmosphere of N2 flow rate of 20 sccm, maintained for 2 h, and cooled to room temperature to obtain a highly dispersed porous nitrogen-doped carbon-supported Ni single atom catalyst; (4) spraying the solution obtained in step (3) onto the surface of the Ar plasma etched carbon paper through a spray gun to use it as the working electrode of the H-type electrolytic cell; (5) The H-type electrolytic cell was separated by a proton exchange membrane, and a Pt sheet was used as the counter electrode of the H-type electrolytic cell. 50 ml of a 0.1 mol / L potassium bicarbonate solution was added to both sides of the H-type electrolytic cell as an electrolyte. Carbon dioxide was introduced as a reaction gas to the working electrode side of the H-type electrolytic cell through a mass flow meter at a flow rate of 30 sccm for at least 30 min to obtain a potassium bicarbonate electrolyte saturated with carbon dioxide; (6) After the carbon dioxide gas is saturated, the electrochemical workstation is turned on, and the catalyst is activated by using the cyclic voltammetry (CV) and linear sweep voltammetry (LSV) methods. Different voltages are applied through the electrochemical workstation to carry out a constant potential electrochemical catalytic reaction for 60 min, and the electrolyte on the working electrode side of the H-type electrolytic cell is collected.

2. The method for electrocatalytic reduction of CO2 using a plasma-enhanced single-atom catalyst according to claim 1, characterized in that: In step (2), the power of the inductively coupled plasma device was set to 100 W and the time was 5 min.

3. The method for electrocatalytic reduction of CO2 using a plasma-enhanced single-atom catalyst according to claim 1, characterized in that: In step (4), the loading amount of Ni single atoms on Ar plasma etched carbon paper is 1 mg / cm 2 .

4. The method for electrocatalytic reduction of CO2 using a plasma-enhanced single-atom catalyst according to claim 1, characterized in that: The reduction of CO2 to CO occurs at the cathode, and the oxidation of H2O to oxygen occurs at the anode.

5. The method for electrocatalytic reduction of CO2 using a plasma-enhanced single-atom catalyst according to claim 1, characterized in that: The outlet gas on the working electrode side of the H-type electrolytic cell is introduced into a gas chromatograph, and the concentration of the gas product CO is detected by the gas chromatograph.

6. The method for electrocatalytic reduction of CO2 using a plasma-enhanced single-atom catalyst according to claim 1, characterized in that: 500 μl of the cathode electrolyte after the reaction was taken, 100 μl of deuterated DMSO solution was added, and the solution was tested by nuclear magnetic resonance, which proved that no liquid phase product was generated.

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