In situ construction of Cu based on heteroatom-induced + / Cu 0 Synthesis method of interfacial nanocatalyst

Abstract

The present invention discloses a method for in-situ construction of Cu based on heteroatom induction + / Cu 0 The synthesis method of interfacial nanocatalysts relates to the technical field of catalytic materials. The molten salt method is used to achieve uniform intermixing of heteroatoms and copper atoms, and a multi-step electrochemical reduction method is used to in situ construct Cu + / Cu 0 In the field of electrochemical CO2 reduction to ethylene, this material can achieve ethylene Faradaic selectivity greater than 70%, far higher than existing Cu-based catalysts, and has the potential for industrial application.

Description

Technical Field

[0001] This application relates to a method for in-situ construction of Cu based on heteroatom-induced + / Cu 0 The invention discloses a method for synthesizing an interfacial nanocatalyst, and belongs to the technical field of preparing ethylene by electrocatalytic carbon dioxide reduction. Background Art

[0002] The development of technologies for reducing the greenhouse gas CO2 is both fundamentally important for basic scientific research and meets current practical needs. Currently, CO2 electrocatalytic reduction remains a highly anticipated research and application technology development direction in the field of electrocatalysis.

[0003] There are many products obtained from the electrocatalytic reduction of CO2, such as carbon monoxide (CO) and formic acid (HCOOH) obtained from the two-electron transfer reaction, methanol (CH3OH) obtained from the six-electron transfer reaction, methane (CH4) obtained from the eight-electron transfer reaction, and ethanol (CH3CH2OH) and ethylene (CH2CH2) obtained from the twelve-electron transfer reaction. Metals with weak adsorption energy, such as Zn, Ag, and Au, tend to desorb directly The formation of CO, and Metals with stronger adsorption energy can further hydrogenate, or even CC coupling. In previous studies, researchers found that Cu The adsorption energy is moderate, which can carry out the next step of hydrogenation and CC coupling process. It is also the only one that can effectively produce C 2+ However, for pure Cu materials with moderate adsorption energy, the distribution of its products is relatively balanced, but this balance leads to low Faradaic efficiency of each product, making it impossible to obtain high-purity specific products.

[0004] In previous studies, researchers found that pulse voltammetry and heterogeneous interface construction methods can induce the formation of Cu + sites, which can achieve high selectivity for the production of ethylene products. However, under strong electroreduction atmosphere, the induced stable existence of Cu + Sites are particularly challenging for catalyst design and activation methods. Summary of the Invention

[0005] In view of the current research status, the present invention provides a method for in-situ construction of Cu based on heteroatom-induced + / Cu 0A method for synthesizing an interfacial nanocatalyst. Using a simple molten salt method, the uniform doping of copper and alkaline earth metals into oxides was successfully achieved. A mild in-situ electrochemical activation process was then used to achieve the reduction of CuO and the removal of alkaline earth metals, which were then loaded onto the surface of the copper element, inducing the formation of stable monovalent copper ions on the copper elemental surface. This catalyst and activation method can increase the Faradaic efficiency of CO2 electrocatalytic reduction to ethylene to over 70%.

[0006] The present invention adopts the following technical solutions:

[0007] A novel heteroatom-induced in-situ Cu + / Cu 0 The method for synthesizing an interfacial nanocatalyst comprises the following steps:

[0008] Step 1, mixing a copper salt, an alkaline earth metal salt and an alkali metal salt, and grinding them to obtain a mixture A;

[0009] Step 2, calcining the mixture A to obtain a calcined mixture B;

[0010] Step 3: Cooling the calcined mixture B, washing with deionized water to remove the alkali metal salt, and drying to obtain a precatalyst;

[0011] Step 4: Add perfluorosulfonic acid solution to the precatalyst obtained in step 3 to form a slurry, spray it into a film, and use the electrochemical activation method to in situ construct the Cu + / Cu 0 Interfacial nanocatalysts.

[0012] Specifically, a novel heteroatom-induced in situ Cu + / Cu 0 The method of interfacial nanocatalysis comprises the following steps:

[0013] Step 1: Precursor Preparation: Grind potassium nitrate or sodium nitrate with copper nitrate and magnesium nitrate for 10 minutes. Add a small amount of ethanol during the grinding process to help dissolve the copper nitrate and magnesium nitrate. Sodium nitrate or potassium nitrate is molten above 400°C and acts like a solvent. Copper nitrate and magnesium nitrate decompose at this temperature to produce oxides. It can be considered that the sodium nitrate or potassium nitrate acts as a template and oxidant.

[0014] Step 2: Heat treatment: Place the ground precursor in a preheated 400°C muffle furnace and calcine for 30 minutes to convert copper nitrate or magnesium nitrate into oxides. Potassium nitrate or sodium nitrate is stable at this temperature.

[0015] Step 3: Drying: The calcined mixture is cooled, rinsed with a large amount of deionized water to remove potassium nitrate or sodium nitrate, and then dried.

[0016] Step 4: Slurry Preparation and Spraying: Using isopropyl alcohol as the solvent, the catalyst and perfluorosulfonic acid solution are added and ultrasonically prepared into a slurry. The perfluorosulfonic acid prevents catalyst shedding during coating and electrochemical operation and provides a cation-rich environment around the catalyst, facilitating the CC coupling process. A pneumatic spray gun is used for uniform application. The substrate used is SGL 28BC carbon paper.

[0017] Electrochemical activation process: 1 M potassium hydroxide was used as electrolyte, mercury / mercuric oxide electrode was used as reference electrode, and nickel foam was used as anode to construct an electrochemical reaction system. Constant current method was used, -100 mA cm -2 Run for half an hour. During the activation process, CuO is continuously reduced and oxidized, and the alkaline earth metals are slowly removed from the bulk phase and then deposited on the surface of the catalyst in the form of clusters. At this time, CuO is completely reduced, and the alkaline earth metals are enriched on the surface of the catalyst in the form of oxygen-containing clusters.

[0018] Optionally, the copper salt is selected from at least one of copper nitrate and copper chloride;

[0019] The alkaline earth metal salt is one or more of magnesium salt, calcium salt and strontium salt;

[0020] The alkali metal salt is selected from one or more of sodium salt and potassium salt;

[0021] The magnesium salt is selected from at least one of magnesium nitrate and magnesium chloride;

[0022] The sodium salt is selected from at least one of sodium nitrate and sodium chloride;

[0023] The potassium salt is selected from at least one of potassium nitrate and potassium chloride;

[0024] The strontium salt is selected from at least one of strontium nitrate and strontium chloride;

[0025] The calcium salt is selected from at least one of calcium nitrate and calcium chloride.

[0026] Optionally, in the catalyst, the molar ratio of the alkaline earth metal heteroatom added is 0% to 10%, based on the total molar number of copper atoms and alkaline earth metal heteroatoms.

[0027] Optionally, in step 1, the mass ratio of the alkaline earth metal salt to the copper salt is 0-25:90-100. For example, the mass ratio of the alkaline earth metal salt to the copper salt is 0, 1:90-100, 2:90-100, 3:90-100, 5:90-100, 7:90-100, 9:90-100, 11:90-100, 13:90-100, 15:90-100, 17:90-100, or 19:90-100.

[0028] Optionally, in step 1, the mass ratio of the alkali metal salt to the copper salt is 16-25:1-2. For example, the mass ratio of the alkali metal salt to the copper salt is 16:1-2, 17:1-2, 18:1-2, 19:1-2, 20:1-2, 21:1-2, 22:1-2, 23:1-2, 24:1-2, or 25:1-2.

[0029] Optionally, the heat treatment (i.e., calcination) conditions are: a temperature of 200-600°C, a time of 0.2-2 hours, and a calcination gas of air or oxygen. For example, the calcination temperature in step 2 is 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, or 600°C, and the time is 0.2 hours, 0.5 hours, 1 hour, 1.5 hours, or 2 hours.

[0030] Optionally, the drying conditions are: temperature of 60-100° C.; time of 1-3 h; and drying gas of air or vacuum.

[0031] Optionally, the electrochemical activation conditions are: constant current method, -50~-200 mA cm -2 Run for 0.1 to 2 hours; preferably -100 mA cm -2 Run for half an hour. For example, the conditions of the electrochemical activation are: constant current method, -50 mAcm -2 、-70 mA cm -2 、-90 mA cm -2 、-110 mA cm -2 、-130 mA cm -2 , -160 mA cm -2 、-180 mA cm -2 or -200 mA cm -2 Run for 0.1 hour, 0.2 hour, 0.4 hour, 0.6 hour, 0.8 hour, 1.2 hour, 1.6 hour, or 2 hours.

[0032] Preferably, the copper salt is selected from copper nitrate; the magnesium salt is selected from magnesium nitrate; the sodium salt is selected from sodium nitrate; and the potassium salt is selected from potassium nitrate. The molar ratio of the alkaline earth metal is 4-6% based on the total molar number of the copper salt, alkaline earth metal salt, and alkali metal salt. The heat treatment temperature is 400°C, the heat treatment time is 0.5 h, and the drying temperature is 60°C in air for 2 h. The electrochemical activation adopts a constant current method, -100 mA cm -2 Run for half an hour.

[0033] The beneficial effects of this application include: the present invention provides a heteroatom-induced in-situ construction of Cu+ / Cu 0 The method of interfacial nanocatalyst is simple, safe, has potential for industrial application, and can achieve ethylene Faradaic selectivity greater than 70%. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is the X-ray diffraction spectrum of Example 1-4;

[0035] Figure 2 The morphology and crystal form changes before and after electrochemical activation of Example 2;

[0036] Figure 3 This is the energy spectrum scan of Example 2 after electrochemical activation;

[0037] Figure 4 X-ray photoelectron spectra of Example 1 and Example 3 after electrochemical activation;

[0038] Figure 5 The electrochemical CO2 reduction data of Examples 1 to 4;

[0039] Figure 6 The electrochemical CO2 activation to ethylene effect of Examples 1 to 4 and the Cu element in the catalyst are Cu + The relationship between the mole percentage. DETAILED DESCRIPTION

[0040] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0041] Synthesis method: Step 1. Put copper nitrate (or copper chloride) and magnesium nitrate (or calcium nitrate, calcium chloride, strontium nitrate and strontium chloride) and potassium nitrate or sodium nitrate into a mortar and grind. Step 2. After grinding, put it into a preheated muffle furnace and calcine it to make copper nitrate or magnesium nitrate into oxide. Step 3. After cooling, rinse with a large amount of deionized water to remove potassium nitrate or sodium nitrate, and dry it. Step 4. Add perfluorosulfonic acid solution to the sample obtained in step 3, prepare it into a slurry, spray it into a film, and use the electrochemical activation method to in situ construct Cu + / Cu 0 Interfacial nanocatalysts.

[0042] Some of the raw materials and equipment used in the following examples of the present invention are as follows:

[0043] 5 wt% perfluorosulfonic acid solution (purchased from Adamas, model D520);

[0044] SGL 28BC carbon paper (manufacturer: SGL, Germany, model number is 28BC);

[0045] Muffle furnace (Kejing KSL-1100X);

[0046] Gas chromatograph (Agilent 7820-5977B).

[0047] Example 1 (Preparation of CuO)

[0048] (1) Preparation of precursor: Place 0.24 g Cu(NO3)2·3H2O and 5.00 g potassium nitrate in a mortar, add 5 ml ethanol, and grind for 10 min.

[0049] (2) Heat treatment: The ground precursor was transferred to a muffle furnace preheated at 400 °C and calcined for 0.5 h.

[0050] (3) Drying: Cool naturally to room temperature, transfer the heat-treated sample to a beaker, add deionized water, stir and dissolve, filter and wash several times until the potassium nitrate is completely removed, transfer the washed sample to an oven, and air dry at 60°C for 2 h to obtain the precatalyst. The mass percentages of the elements Cu and Mg in the precatalyst are shown in Table 1.

[0051] (4) Slurry preparation and spraying: Weigh 5 mg of precatalyst, add 1.5 ml of isopropanol and 35 μL of 5 wt% perfluorosulfonic acid solution, mix well, and prepare slurry. Use a pneumatic spray gun with a nozzle of 0.3 mm inner diameter to spray onto the microporous surface of SGL 28BC carbon paper, with a spraying load of 1 mg / cm 2 , and dried at 60°C for 30 min to obtain a carbon paper-supported pre-catalyst coating.

[0052] (5) The carbon paper-supported pre-catalyst coating obtained in step (4) was electrochemically activated using 1 M potassium hydroxide as the electrolyte, a mercury / mercuric oxide electrode as the reference electrode, and nickel foam as the anode to construct an electrochemical reaction system. During the electrochemical activation process, a constant current method was used, with a flow rate of -100 mA cm -2 Run for half an hour to obtain the catalyst.

[0053] (6) Electrochemical carbon dioxide reduction reaction: The catalyst obtained in step (5) was used as the working electrode, and the IrO2 / Ti mesh (Tianjin Gaoshi Ruilian, the IrO2 loading on the Ti mesh was 1 mg / cm 2 , the same as in the following examples) was used as the anode catalyst and 1MKHCO3 was used as the electrolyte. The full cell performance of the catalyst was tested in a MEA electrolytic cell. -2 The results of gas chromatography (GC) showed that ethylene was still the main product at all applied current densities. -2 The Faradaic efficiency of reducing carbon dioxide to ethylene is 47% at a current density of 4.

[0054] Calculation of gas phase FE: ;

[0055] Where n is the number of electrons transferred from CO2 to the gas phase product (e.g., 2 electrons for CO, 8 electrons for CH4, 12 electrons for C2H4, etc.); F is the Faraday constant (96485 Cmol -1 ); C i is the concentration of the gas phase product volume detected in GC (ppm); I is the total catalyst current (mA); P is the standard atmospheric pressure (1.01×10 5 Pa); R is the thermodynamic constant (8.314 Jmol -1 K -1 ), T is room temperature (293.15 K); u is the flow rate of CO2 gas (m 3 s -1 ).

[0056] Example 2 (Preparation of 2wt% Mg-doped Nano-CuO)

[0057] (1) Preparation of precursor: Place 0.24 g Cu(NO3)2·3H2O, 0.017 g Mg(NO3)2·6H2O, and 5.00 g potassium nitrate in a mortar, add 5 ml ethanol, and grind for 10 min.

[0058] (2) Heat treatment: The ground precursor was transferred to a muffle furnace preheated at 400 °C and calcined for 0.5 h.

[0059] (3) Drying: Cool naturally to room temperature, transfer the heat-treated sample to a beaker, add deionized water, stir and dissolve, filter and wash several times until the potassium nitrate is completely removed, transfer the washed sample to an oven, and air dry at 60°C for 2 h to obtain the precatalyst. The mass percentages of the elements Cu and Mg in the precatalyst are shown in Table 1.

[0060] (4) Slurry preparation and spraying: Weigh 5 mg of precatalyst, add 1.5 ml of isopropanol and 35 μL of 5 wt% perfluorosulfonic acid solution, mix well, and prepare slurry. Use a pneumatic spray gun with a 0.3 mm nozzle to spray onto the microporous surface of SGL 28BC carbon paper, with a spray loading of 1 mg / cm 2 , and dried at 60°C for 30 min to obtain a carbon paper-supported pre-catalyst coating.

[0061] (5) The carbon paper-supported pre-catalyst coating obtained in step (4) was electrochemically activated using 1 M potassium hydroxide as the electrolyte, a mercury / mercuric oxide electrode as the reference electrode, and nickel foam as the anode to construct an electrochemical reaction system. During the electrochemical activation process, a constant current method was used, with a flow rate of -100 mA cm -2 Run for half an hour.

[0062] (6) Electrochemical CO2 reduction reaction: The catalyst obtained in step (5) was used as the working electrode, IrO2 / Ti mesh as the anode catalyst, and 1M KHCO3 as the electrolyte. The full cell performance of the catalyst was tested in a MEA electrolytic cell. -2 The results of gas chromatography (GC) showed that ethylene was the main product at all applied current densities, and at 200 mAcm -2 The Faradaic efficiency of reducing carbon dioxide to ethylene is 65% at a current density of 1.5 %.

[0063] Calculation of gas phase FE: ;

[0064] Where n is the number of electrons transferred from CO2 to the gas phase product (e.g., 2 electrons for CO, 8 electrons for CH4, 12 electrons for C2H4, etc.); F is the Faraday constant (96485 Cmol -1 ); C i is the concentration of the gas phase product volume detected in GC (ppm); I is the total catalyst current (mA); P is the standard atmospheric pressure (1.01×10 5 Pa); R is the thermodynamic constant (8.314 Jmol -1 K -1 ), T is room temperature (293.15 K); u is the flow rate of CO2 gas (m 3 s -1 ).

[0065] Example 3 (Preparation of 4wt% Mg-doped Nano-CuO)

[0066] (1) Preparation of precursor: Place 0.24 g Cu(NO3)2·3H2O, 0.034 g Mg(NO3)2·6H2O, and 5.00 g potassium nitrate in a mortar, add 5 ml ethanol, and grind for 10 min.

[0067] (2) Heat treatment: The ground precursor was transferred to a muffle furnace preheated at 400 °C and calcined for 0.5 h.

[0068] (3) Drying: Cool naturally to room temperature, transfer the heat-treated sample to a beaker, add deionized water, stir and dissolve, filter and wash several times until the potassium nitrate is completely removed, transfer the washed sample to an oven, and air dry at 60°C for 2 h to obtain the precatalyst. The mass percentages of the elements Cu and Mg in the precatalyst are shown in Table 1.

[0069] (4) Slurry preparation and spraying: Weigh 5 mg of precatalyst, add 1.5 ml of isopropanol and 35 μL of 5 wt% perfluorosulfonic acid solution, mix well, and prepare slurry. Use a pneumatic spray gun with a 0.3 mm nozzle to spray onto the microporous surface of SGL 28BC carbon paper, with a spray loading of 1 mg / cm 2 , and dried at 60°C for 30 min to obtain a carbon paper-supported pre-catalyst coating.

[0070] (5) The carbon paper-supported pre-catalyst coating obtained in step (4) was electrochemically activated using 1 M potassium hydroxide as the electrolyte, a mercury / mercuric oxide electrode as the reference electrode, and nickel foam as the anode to construct an electrochemical reaction system. During the electrochemical activation process, a constant current method was used, with a flow rate of -100 mA cm -2 Run for half an hour.

[0071] (6) Electrochemical CO2 reduction reaction: The catalyst obtained in step (5) was used as the working electrode, IrO2 / Ti mesh as the anode catalyst, and 1M KHCO3 as the electrolyte. The full cell performance of the catalyst was tested in a MEA electrolytic cell. -2 The results of gas chromatography (GC) showed that ethylene was the main product at all applied current densities, and at 300 mAcm -2 The Faradaic efficiency of reducing carbon dioxide to ethylene is 78% at a current density of 1.5 %.

[0072] Calculation of gas phase FE: ;

[0073] Where n is the number of electrons transferred from CO2 to the gas phase product (e.g., 2 electrons for CO, 8 electrons for CH4, 12 electrons for C2H4, etc.); F is the Faraday constant (96485 Cmol -1 ); C i is the concentration of the gas phase product volume detected in GC (ppm); I is the total catalyst current (mA); P is the standard atmospheric pressure (1.01×10 5 Pa); R is the thermodynamic constant (8.314 Jmol -1 K -1 ), T is room temperature (293.15 K); u is the flow rate of CO2 gas (m3 s -1 ).

[0074] Example 4 (Preparation of 6wt% Mg-doped Nano-CuO)

[0075] (1) Preparation of precursor: Place 0.24 g Cu(NO3)2·3H2O, 0.051 g Mg(NO3)2·6H2O, and 5.00 g potassium nitrate in a mortar, add 5 ml ethanol, and grind for 10 min.

[0076] (2) Heat treatment: The ground precursor was transferred to a muffle furnace preheated at 400 °C and calcined for 0.5 h.

[0077] (3) Drying: Cool naturally to room temperature, transfer the heat-treated sample to a beaker, add deionized water, stir and dissolve, filter and wash several times until the potassium nitrate is completely removed, transfer the washed sample to an oven, and air dry at 60°C for 2 h to obtain the precatalyst. The mass percentages of the elements Cu and Mg in the precatalyst are shown in Table 1.

[0078] (4) Slurry preparation and spraying: Weigh 5 mg of precatalyst, add 1.5 ml of isopropanol and 35 μL of 5 wt% perfluorosulfonic acid solution, mix well, and prepare slurry. Use a pneumatic spray gun with a 0.3 mm nozzle to spray onto the microporous surface of SGL 28BC carbon paper, with a spray loading of 1 mg / cm 2 , and dried at 60°C for 30 min to obtain a carbon paper-supported pre-catalyst coating.

[0079] (5) The carbon paper-supported pre-catalyst coating obtained in step (4) was electrochemically activated using 1 M potassium hydroxide as the electrolyte, a mercury / mercuric oxide electrode as the reference electrode, and nickel foam as the anode to construct an electrochemical reaction system. During the electrochemical activation process, a constant current method was used, with a flow rate of -100 mA cm -2 Run for half an hour.

[0080] (6) Electrochemical CO2 reduction reaction: The catalyst obtained in step (5) was used as the working electrode, IrO2 / Ti mesh as the anode catalyst, and 1M KHCO3 as the electrolyte. The full cell performance of the catalyst was tested in a MEA electrolytic cell. -2 The results of gas chromatography (GC) showed that ethylene was the main product at all applied current densities, and at 300 mAcm -2 The Faradaic efficiency of reducing carbon dioxide to ethylene at a current density of 76% is 76%.

[0081] Calculation of gas phase FE: ;

[0082] Where n is the number of electrons transferred from CO2 to the gas phase product (e.g., 2 electrons for CO, 8 electrons for CH4, 12 electrons for C2H4, etc.); F is the Faraday constant (96485 Cmol -1 ); C i is the concentration of the gas phase product volume detected in GC (ppm); I is the total catalyst current (mA); P is the standard atmospheric pressure (1.01×10 5 Pa); R is the thermodynamic constant (8.314 Jmol -1 K -1 ), T is room temperature (293.15 K); u is the flow rate of CO2 gas (m 3 s -1 ).

[0083] Examples and diagrams:

[0084] (1) Examples 1 to 4 are about obtaining Mg-CuO with different doping concentrations by adjusting the Mg doping ratio in the precursor. Table 1 shows the actual Mg doping ratio measured by plasma emission spectroscopy, indicating that the actual Mg content is consistent with the Mg precursor feed ratio.

[0085] Table 1. Actual elemental composition of the samples (i.e., precatalysts) in Examples 1 to 4. The mass percentages of the elements are based on the total mass of the samples.

[0086]

[0087] (2) According to Figure 1 The X-ray diffraction spectrum shows that when the Mg doping ratio is below 4wt%, Mg exists in the CuO crystal phase in the form of doping.

[0088] (3) During the electrochemical activation process in Examples 1 to 4, the CuO phase will be activated into a single copper crystal phase, and Mg will slowly precipitate and deposit on the surface of the reduced single Cu. Figure 2 The microscopic morphology changes of Example 2 before and after electrochemical activation are shown. Figure 2 In the figure, (a) is the micromorphology of the precatalyst before electrochemical activation, (b) is the micromorphology of the precatalyst after electrochemical activation, and (c) is the crystal form change of the precatalyst before and after electrochemical activation. Figure 2 After electrochemical activation, a layer of low-contrast amorphous phase material appears on the outer edge of the material. Through energy spectrum scanning and X-ray diffraction spectrum, Figure 3(a) is the high-angle annular dark field (HADDF) image of the pre-catalyst after electrochemical activation, (b) is the Mg element distribution map after electrochemical activation of the pre-catalyst, and (c) is the Cu element distribution map after electrochemical activation of the pre-catalyst, which proves that the low-contrast material on the periphery of the pre-catalyst in Example 2 is a Mg-containing phase after electrochemical activation, and the internal CuO has been completely reduced to elemental Cu.

[0089] (4) Figure 4 (a) is the X-ray photoelectron spectrum of the catalyst obtained in Example 1, and (b) is the X-ray photoelectron spectrum of the catalyst obtained in Example 3. The X-ray photoelectron spectrum explains the effect of the Mg-containing amorphous phase on the microscopic chemical environment of the elemental Cu outside the catalyst. As shown in the figure, the surface state Cu in Example 3 + The ratio of / Cu is much higher than that in Example 1. There are a large number of unsaturated coordination sites in the Mg-containing amorphous phase. These sites can interact with the surface of elemental Cu, induce electron delocalization on the surface of elemental Cu, and form Cu + Location.

[0090] (5) Figure 5 (a) shows the Faradaic efficiencies of carbon monoxide, methane, ethylene, and hydrogen, the products of the electrocatalytic reduction of carbon dioxide, at different current densities, using the catalyst obtained in Example 1. The Faradaic selectivity for ethylene reached a maximum of 47%. (b) shows the Faradaic efficiencies of carbon monoxide, methane, ethylene, and hydrogen, the products of the electrocatalytic reduction of carbon dioxide, using the catalyst obtained in Example 2, at different current densities. The Faradaic selectivity for ethylene reached a maximum of 65%.

[0091] (c) shows the Faradaic efficiencies of carbon monoxide, methane, ethylene, and hydrogen, the products of electrocatalytic carbon dioxide reduction, for the catalyst obtained in Example 3 at different current densities. The Faradaic selectivity for ethylene reaches a maximum of 78%. (d) shows the Faradaic efficiencies of carbon monoxide, methane, ethylene, and hydrogen, the products of electrocatalytic carbon dioxide reduction, for the catalyst obtained in Example 4 at different current densities. The Faradaic selectivity for ethylene reaches a maximum of 76%. These results demonstrate the effectiveness of the catalysts in Examples 1-4. Comparison reveals that the catalysts in Examples 2-4 all exhibit enhanced Faradaic efficiencies for ethylene compared to Example 1. These results demonstrate that the Mg doping strategy provided by the present invention can effectively increase the efficiency of electrochemical CO2 reduction to ethylene.

[0092] (6) Figure 6 The Cu in Examples 1 to 4 is shown + The volcano plot relationship between the ratio of Cu and ethylene selectivity. The results show that the Faradaic efficiency of ethylene in the electrochemical CO2 reduction process is closely related to the Cu +It also explains that the role of the doping method provided by the present invention, that is, the electrochemical activation method, is to use the electrochemical method to precipitate the amorphous phase of Mg in situ, thereby inducing and stabilizing Cu + The formation of ethylene is promoted.

[0093] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method based on heteroatom-induced in-situ construction of Cu + / Cu 0 The method for synthesizing an interfacial nanocatalyst is characterized in that: The following steps are involved: Step 1, mixing a copper salt, an alkaline earth metal salt and an alkali metal salt, and grinding them to obtain a mixture A; Step 2, calcining the mixture A to obtain a calcined mixture B; Step 3, cooling the calcined mixture B, removing the alkali metal salt, and drying to obtain a precatalyst; Step 4: Add perfluorosulfonic acid solution to the precatalyst obtained in step 3 to prepare a slurry, spray it into a film, and use the electrochemical activation method to in situ construct the Cu + / Cu 0 Interface nanocatalyst; the electrochemical activation conditions are: constant current method, -50~-200mA cm -2 Run for 0.1~2 hours; In step 1, the alkaline earth metal salt is selected from one or more of magnesium nitrate, calcium nitrate, calcium chloride, strontium nitrate and strontium chloride, and the mass ratio of the alkaline earth metal salt to the copper salt is 1-25:90-100.

2. The heteroatom-induced in-situ construction of Cu according to claim 1 + / Cu 0 The method for synthesizing an interfacial nanocatalyst is characterized in that: In the step 1, the copper salt is selected from one or both of copper nitrate and copper chloride.

3. The heteroatom-induced in-situ construction of Cu according to claim 1 + / Cu 0 The method for synthesizing an interfacial nanocatalyst is characterized in that: In step 1, the alkali metal salt is selected from one or both of potassium nitrate and sodium nitrate; and the mass ratio of the alkali metal salt to the copper salt is 16-25:1-2.

4. The heteroatom-induced in-situ construction of Cu according to claim 1 + / Cu 0 The method for synthesizing an interfacial nanocatalyst is characterized in that: The calcination temperature in step 2 is 200-600° C. and the calcination time is 0.2-2 h.

5. The heteroatom-induced in-situ construction of Cu according to claim 1 + / Cu 0 The method for synthesizing an interfacial nanocatalyst is characterized in that: The drying temperature in step 3 is 60-100° C., the drying atmosphere is air or vacuum, and the drying time is 1-3 hours.

6. The heteroatom-induced in-situ construction of Cu according to claim 1 + / Cu 0 The method for synthesizing an interfacial nanocatalyst is characterized in that: The slurry is prepared by adding isopropyl alcohol solvent, pre-catalyst and 5 wt% perfluorosulfonic acid solution, and ultrasonicating for 1 to 3 hours to achieve uniform dispersion; The ratio of isopropanol solvent: precatalyst: 5wt% perfluorosulfonic acid solution is 1~2 mL: 5~10 mg: 20~40 μL.

7. The heteroatom-induced in-situ construction of Cu according to claim 1 + / Cu 0 The method for synthesizing an interfacial nanocatalyst is characterized in that: The spraying method in step 4 is to use a pneumatic spray gun with an inner diameter of 0.3-0.5 mm to spray the slurry onto the microporous surface of the carbon paper at a spraying amount of 0.5-2 mg / cm 2 .

8. The heteroatom-induced in-situ construction of Cu according to claim 1 + / Cu 0 The method for synthesizing an interfacial nanocatalyst is characterized in that: The electrochemical activation in step 4 was performed using a constant current method, 100 mA cm -2 Run for half an hour.

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