Carbon dioxide electroreduction catalyst and method of making same

Abstract

The application relates to the technical field of catalysts, and discloses a carbon dioxide electro-reduction catalyst, which is Ag@CuO@Cu-MOF, wherein Ag is silver, CuO is copper oxide, and Cu-MOF is a Cu metal framework; the CuO is coated on the surface of the Ag, and the Cu-MOF is coated on the surface of the CuO. The catalyst obtained by the application can exhibit high selectivity to C2 products in the carbon dioxide electro-reduction process, and can fully utilize CO.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular to a carbon dioxide electro-reduction catalyst and a preparation method thereof. BACKGROUND

[0002] In the process of carbon dioxide electro-catalytic reduction (CO2RR), both theoretical calculation and experimental results show that CO is an important intermediate for the generation of C2H4 in CO2RR, and the higher the coverage of CO on the surface of the catalyst, the lower the overpotential for the generation of C2H4, indicating that the increase in the amount of CO improves the probability of C-C coupling. Therefore, the combination of Ag, Au and other CO-selective electro-catalysts with Cu can improve the selectivity and reaction rate of Cu for C2 products. The CO produced on the surface of Ag, Au and other materials can overflow to the surface of Cu-based catalysts in different ways, thereby promoting the C-C coupling reaction rate and the selectivity of C2 products on the surface of Cu-based catalysts. The above synthesis strategy gradually improves the selectivity of Cu-based catalysts for C2 products, but the tandem catalyst still has the shortcomings of insufficient utilization of CO and low selectivity of C2 products, and how to reasonably arrange the spatial distribution of the tandem catalyst to improve the working efficiency of the tandem catalyst still faces challenges. In addition, CuO or Cu2O is easily reduced to Cu in the process of carbon dioxide electro-catalytic reduction, which also reduces the selectivity of C2 products.

[0003] In the prior art, researchers have obtained catalyst products with improved selectivity for C2 products by using a tandem CO2RR catalyst, but the results show that during the catalysis process of the tandem catalyst, due to the uneven distribution of CO on the surface of the tandem catalyst, the local CO concentration of the catalyst is too high or too low, which leads to the inability to fully utilize CO and the low selectivity of C2 products. Therefore, how to reasonably arrange the spatial distribution of the tandem catalyst to improve the working efficiency of the tandem catalyst still faces challenges. SUMMARY

[0004] To solve the above technical problems, the present application provides a carbon dioxide electro-reduction catalyst, which can fully utilize CO and has high selectivity for C2 products. The structure of the catalyst can make the CO produced on the surface of Ag overflow to the surface of CuO, thereby improving the selectivity of C2, and the Cu-MOF on the surface of CuO can prevent the complete reduction of CuO to Cu, thereby improving the stability of the catalyst.

[0005] The present application provides a carbon dioxide electro-reduction catalyst, which is Ag@CuO@Cu-MOF, wherein Ag is silver, CuO is copper oxide, and Cu-MOF is a Cu metal framework; the CuO is coated on the surface of Ag, and the Cu-MOF is coated on the surface of CuO.

[0006] In the present application, Ag@CuO@Cu-MOF, wherein "@" is used to represent that the substance after "@" is coated on the substance before "@".

[0007] Further, the Ag is Ag nanowire with a length of 1-100 mu m and a cross-sectional diameter of 10-100 nm.

[0008] The present application also provides a preparation method of the carbon dioxide electro-reduction catalyst, which comprises:

[0009] S1: adding copper precursor, polyvinylpyrrolidone and Ag nanowire in ethylene glycol solution under inert atmosphere, mixing uniformly, heating and stirring, centrifuging, washing and drying to obtain Ag@Cu2O;

[0010] S2: dispersing Ag@Cu2O in a mixed solution of deionized water and ethanol, adding inorganic base and passing in oxygen for oxidation treatment, centrifuging and drying to obtain intermediate product Ag@CuO;

[0011] S3: dispersing the intermediate product in liquid reagent, adding organic ligand, transferring to hydrothermal kettle after mixing uniformly, heating, centrifuging, washing and drying to obtain the catalyst of the present application.

[0012] Further, the copper precursor comprises one or more of copper nitrate trihydrate, copper acetate, copper sulfate, copper chloride, basic copper carbonate and copper oxalate.

[0013] Further, the inorganic base comprises one or more of sodium hydroxide, potassium hydroxide, concentrated ammonia water and cesium hydroxide.

[0014] Further, the organic ligand comprises one or more of terephthalic acid, trimesic acid, 2-fluoroterephthalic acid, 2-hydroxyterephthalic acid, 2,3,6,7,10,11-hexahydroxytriphenyl, isonicotinic acid, 2-fluoroisonicotinic acid and 2-hydroxyisonicotinic acid.

[0015] Further, the liquid reagent comprises one or more of water, N,N-dimethylformamide, ethanol, ethylene glycol and acetamide.

[0016] Further, the inert atmosphere comprises one of nitrogen and argon.

[0017] Further, the mass ratio of the copper precursor, polyvinylpyrrolidone, Ag nanowire and ethylene glycol is 1-5:1-5:2-10:150-500.

[0018] Further, the heating and stirring temperature in S1 is 130-180 DEG C, the heating time is 5-30 min, and the heating and stirring speed is 20-200 r / min.

[0019] Further, the drying condition in S1 is 60-100℃ vacuum drying for 8-12h.

[0020] Further, the reagent used for washing in S1 is ethanol solution, and the number of washing is at least 4 times.

[0021] Further, the concentration of Ag@Cu2O in the mixed solution in S2 is 1-20mg / mL.

[0022] Further, the molar ratio of deionized water, ethanol, inorganic base in S2 is 100-200:10-100:0.1-100.

[0023] Further, the time of oxidation treatment in S2 is 20-80min, and the flow rate of oxygen is 10-20mL / min.

[0024] Further, the drying condition in S2 is 60-100℃ vacuum drying for 8-12h.

[0025] Further, the concentration of intermediate product in liquid reagent in S3 is 2-10mg / mL.

[0026] Further, the concentration of organic ligand in liquid reagent in S3 is 1-5mg / mL.

[0027] Further, the heating temperature in S3 is 60-140℃, and the heating time is 1-12h.

[0028] Further, the reagent used for washing in S3 is one or more of ethanol, methanol, N,N-dimethylformamide, and the number of washing is at least 4 times.

[0029] Further, the drying condition in S3 is 60-100℃ vacuum drying for 6-12h.

[0030] Further, the preparation method of Ag nanowires in S1 comprises: adding PVP (polyvinylpyrrolidone) in ethylene glycol solution, heating and dissolving, cooling; then adding sodium chloride, stirring and dissolving; then adding silver nitrate, stirring and dissolving under light-proof condition; and putting the obtained mixed solution into an oven for heating under light-proof condition.

[0031] Further, the molar ratio of PVP, sodium chloride, silver nitrate, ethylene glycol is 15-25:10-20:0.1-0.3:2000-5000.

[0032] Further, the preparation method of the Ag nanowire is that the temperature of heating and dissolving is 100-150 DEG C, and the heating time is 4-16 hours.

[0033] Further, after heating, the preparation method of the Ag nanowire needs to be cooled.

[0034] Further, the cooling mode can adopt the natural cooling mode, and the person skilled in the art can cool by other modes, such as accelerating the cooling speed by stirring.

[0035] Further, the ethylene glycol solution of the Ag nanowire can be directly used for the next step of synthesizing Ag@Cu2O after cooling without any treatment, and the content of the synthesized Ag nanowire is calculated according to the addition amount of AgNO3.

[0036] The application also provides application of the catalyst in carbon dioxide electro-reduction.

[0037] The application embodiment has the following technical effects:

[0038] 1. The catalyst obtained in the application can exhibit high selectivity for C2 products in the process of carbon dioxide electro-reduction, and can fully utilize CO.

[0039] 2. In the application, CuO and Cu-MOF are distributed in a zigzag shape around the Ag nanowire, which is beneficial to diffusion of CO2 to the surface of the Ag nanowire, diffusion of CO generated by the Ag nanowire to active sites in CuO and Cu-MOF in time, and further reduction of the C2 products.

[0040] 3. In the product of the application, CuO is coated on the surface of the Ag nanowire, and Cu-MOF is coated on the surface of CuO to form a coating structure. The Cu-MOF metal framework can not only facilitate uniform and rapid adsorption of CO2 in the catalyst, but also facilitate CuO to maintain an oxidation state under the condition of carbon dioxide electro-reduction, so as to ensure continuous and efficient generation of C2 products and improve the stability of the catalyst. On this basis, the introduction of Ag can quickly convert CO2 to provide more CO intermediates for copper, thereby improving the selectivity and conversion efficiency of the catalyst for C2 products. In the case, in order to further balance the generation rate and consumption rate of CO, reduce the decline of CO utilization rate caused by uniform distribution of CO on the surface of the catalyst, the product in the case adopts the coating mode, and the layers are in sufficient and uniform contact with each other, so as to facilitate uniform distribution of CO in the catalyst and reduce the CO that cannot be fully utilized due to local high or low concentration of the catalyst; and the connection between the layers is beneficial to shorten the reaction path, thereby improving the reaction efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the specific embodiments or the prior art, the following will briefly introduce the drawings needed to be used in the description of the specific embodiments or the prior art. Obviously, the drawings described below are only some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative work based on these drawings also belong to the protection scope of the present application.

[0042] Figure 1 are SEM and SEM-EDS images of Example 1-Example 2 provided by the embodiments of the present application, wherein Figure 1 (a) is the SEM image of Example 1, Figure 1 (b) is the SEM-EDS image of Example 2, Figure 1 (c) is the SEM-EDS image of Example 1, Figure 1 (d) is the SEM-EDS image of Example 2.

[0043] Figure 2 is the XRD image of Example 1.

[0044] Figure 3 are test results of carbon dioxide electro-reduction of Example 1-Example 6 and Comparative Example 1-Comparative Example 2 in H-type electrolytic cell, wherein Figure 3 (a) is the test result of Example 1, Figure 3 (b) is the test result of Example 2, Figure 3 (c) is the test result of Example 3, Figure 3 (d) is the test result of Example 4, Figure 3 (e) is the test result of Example 5, Figure 3 (f) is the test result of Example 6, Figure 3 (g) is the test result of Comparative Example 1, Figure 3 (h) is the test result of Comparative Example 2. DETAILED DESCRIPTION

[0045] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the protection scope of the present application.

[0046] In the first aspect, some embodiments of the present application provide a core-shell type carbon dioxide electro-reduction catalyst, the catalyst is Ag@CuO@Cu-MOF, wherein Ag is silver, CuO is copper oxide, and Cu-MOF is Cu metal framework; the CuO is coated on the surface of Ag, and the Cu-MOF is coated on the surface of CuO.

[0047] In the present application, in the process of carbon dioxide electro-reduction, firstly, the metal framework structure of Cu-MOF is conducive to the adsorption of CO2 into the catalyst, and the introduction of Ag can quickly convert CO2 to provide more CO intermediates for copper, thereby improving the selectivity of the catalyst to C2 products. And in order to improve the stability of the catalyst and continuously and efficiently generate C2 products, the Cu-MOF provided in the product of the present application can stabilize the oxidation state of Cu in the CuO layer, thereby ensuring the continuous and efficient generation of C2 products and improving the stability of the catalyst.

[0048] In the present application, the layers are connected in a way of coating, firstly, because it can promote sufficient and uniform contact between layers, thereby facilitating uniform distribution of CO in the catalyst and reducing the inability of CO to be fully utilized due to excessively high or low local concentration of the catalyst; secondly, the connection between layers is conducive to shortening the reaction path, thereby facilitating the improvement of reaction efficiency; thirdly, the Cu-MOF layer can maximize the protection of CuO from being completely reduced to Cu element, thereby facilitating the improvement of the selectivity of C2 products.

[0049] In some embodiments, the length of Ag is 1-100 microns, and the cross-sectional diameter of the nanowire is 10-100 nanometers.

[0050] Further, the present application also provides a preparation method of the carbon dioxide electro-reduction catalyst, the preparation method comprising:

[0051] S1: adding copper precursor, polyvinylpyrrolidone and Ag nanowire in ethylene glycol solution under inert atmosphere, mixing uniformly, heating and stirring reaction, centrifuging, washing and drying to obtain Ag@Cu2O;

[0052] S2: dispersing Ag@Cu2O in a mixed solution of deionized water and ethanol, adding inorganic base and introducing oxygen for oxidation treatment, centrifuging and drying to obtain intermediate product Ag@CuO;

[0053] S3: dispersing the intermediate product in a liquid reagent, adding organic ligand, transferring to a hydrothermal kettle after mixing uniformly, heating, centrifuging, washing and drying to obtain the catalyst of the present application.

[0054] In the present application, the selection of Ag nanowire and the thickness of CuO can on the one hand reduce the size of the final catalyst, thereby facilitating the improvement of the activity of the catalyst; on the other hand, it can balance the generation rate and consumption rate of CO in the process of carbon dioxide electro-reduction, thereby facilitating the reduction of the decrease of CO utilization rate caused by the uniform distribution of CO on the surface of the catalyst. In the method of the present application, the thickness of CuO is adjusted by adjusting the addition amount of organic ligand.

[0055] In some embodiments, the copper precursor includes one or more of copper nitrate trihydrate, copper acetate, copper sulfate, copper chloride, basic copper carbonate, copper oxalate.

[0056] In some embodiments, the inorganic base includes one or more of sodium hydroxide, potassium hydroxide, concentrated ammonia, cesium hydroxide.

[0057] In some embodiments, the organic ligand includes one or more of terephthalic acid, trimesic acid, 2-fluoroterephthalic acid, 2-hydroxyterephthalic acid, 2,3,6,7,10,11-hexahydroxytriphenyl, isonicotinic acid, 2-fluoroisonicotinic acid, 2-hydroxyisonicotinic acid.

[0058] In some embodiments, the liquid reagent includes one or more of water, N,N-dimethylformamide, ethanol, ethylene glycol, acetamide.

[0059] In some embodiments, the inert atmosphere includes one of nitrogen, argon.

[0060] In some embodiments, the molar ratio of the copper precursor, polyvinylpyrrolidone, Ag nanowire, and ethylene glycol is 1-5: 1-5: 2-10: 150-500.

[0061] In some embodiments, the temperature of the heating and stirring in S1 is 130-180°C, and the heating time is 5-30 min; the speed of the heating and stirring is 20-200 r / min.

[0062] In some embodiments, the drying condition in S1 is vacuum drying at 60-100°C for 8-12 h.

[0063] In some embodiments, the reagent used for washing in S1 is an ethanol solution, and the number of washing is at least 4 times.

[0064] In some embodiments, the concentration of Ag@Cu2O in the mixed solution in S2 is 1-20 mg / mL.

[0065] In some embodiments, the molar ratio of the deionized water, ethanol, and inorganic base in S2 is 100-200: 10-100: 0.1-100.

[0066] In some embodiments, the time of the oxidation treatment in S2 is 20-80 min, and the flow rate of oxygen is 10-20 mL / min.

[0067] In some embodiments, the drying condition in S2 is vacuum drying at 60-100°C for 8-12 h.

[0068] In some embodiments, the concentration of the intermediate product in S3 in the liquid reagent is 2 mg / mL to 10 mg / mL.

[0069] In some embodiments, the concentration of the organic ligand in S3 in the liquid reagent is 1 mg / mL to 5 mg / mL.

[0070] In some embodiments, the heating temperature in step S3 is 60°C-140°C, and the heating time is 1h-12h.

[0071] In some embodiments, the reagent used for washing in S3 is one or more of ethanol, methanol, and N,N-dimethylformamide, and the washing is performed at least four times.

[0072] In some embodiments, the drying conditions in S3 are vacuum drying at 60°C-100°C for 6-12 hours.

[0073] In some embodiments, the preparation method of Ag nanowires in S1 includes: adding PVP (polyvinylpyrrolidone) to an ethylene glycol solution, heating to dissolve, and cooling; then adding sodium chloride and stirring to dissolve; then adding silver nitrate and stirring to dissolve under light-protected conditions; and placing the resulting mixed solution in an oven for heating under light-protected conditions.

[0074] In some embodiments, the molar ratio of PVP, sodium chloride, silver nitrate, and ethylene glycol is 15-25:10-20:0.1-0.3:2000-5000.

[0075] In some embodiments, the Ag nanowires are prepared by heating and dissolving at a temperature of 100°C-150°C for 4-16 hours.

[0076] In some embodiments, the Ag nanowires are prepared by heating and then cooling.

[0077] Thirdly, some embodiments of the present invention provide the application of the catalyst in the electroreduction of carbon dioxide.

[0078] The following description, in conjunction with specific embodiments, provides further details.

[0079] Example 1:

[0080] Preparation of Ag nanowires: 2g PVP was added to 160mL ethylene glycol, stirred and heated to 150℃, maintained for 2h, and then allowed to cool naturally; 6.72mg NaCl was added to 16mL ethylene glycol and stirred to dissolve; 2g AgNO3 was dissolved in 40mL ethylene glycol. The above three solutions were mixed and stirred for 5min, then placed in an oven at 110℃ for 12h to obtain Ag nanowire structures.

[0081] Preparation of Ag@Cu2O: 180 mg Cu(NO3)2·3H2O and 200 mg PVP were dissolved in 10 mL ethylene glycol. Then, 10 mL of Ag nanowire solution was added to the above solution, and argon gas was introduced as a protective gas. The mixture was stirred for 30 min. Subsequently, the mixture was heated to 160 °C and reacted for 15 min. After the mixed solution cooled, it was centrifuged and washed four times with a mixture of ethanol and water. The sample was then dried in a vacuum drying oven at 60 °C for 8 h to obtain the Ag@Cu2O sample.

[0082] Preparation of Ag@CuO: Disperse 20 mg Ag@Cu2O sample in 25 mL ethanol, add 5 mL deionized water, and then add 1 mL concentrated ammonia under stirring. Stir for 2 h, centrifuge, wash 4 times with a mixed solution of ethanol and water, and dry in a vacuum drying oven at 60 ℃ for 8 h to obtain the corresponding Ag@CuO sample.

[0083] Preparation of Ag@Cu@Cu-MOF: 20 mg Ag@CuO was dispersed in a mixed solution of 10 mL N,N-dimethylformamide, 1 mL ethanol, and 1 mL deionized water. Then, 20 mg terephthalic acid was added and mixed thoroughly. The dispersion was then placed in a 50 mL hydrothermal reactor and heated at 120 °C for 3 h. After natural cooling, the mixture was centrifuged, washed four times with an ethanol-water mixture, and dried in a vacuum drying oven at 60 °C for 8 h to obtain the corresponding Ag@CuO@Cu-MOF-1 sample.

[0084] Example 2:

[0085] In this embodiment, the 20 mg of terephthalic acid in the Ag@Cu@Cu-MOF preparation step of Example 1 was replaced with 2-fluoro-terephthalic acid, while all other conditions remained the same. The resulting sample was designated Ag@CuO@Cu-MOF-2. The carbon dioxide electrocatalytic reduction performance test was conducted in the same manner as in Example 1.

[0086] Example 3:

[0087] In this embodiment, the 20 mg terephthalic acid in the Ag@Cu@Cu-MOF preparation step of Example 1 was replaced with trimellitic acid, while all other conditions remained the same. The resulting sample was designated Ag@CuO@Cu-MOF-3. The carbon dioxide electrocatalytic reduction performance test was conducted in the same manner as in Example 1.

[0088] Example 4:

[0089] In this example, 20 mg of isonicotinic acid is used instead of terephthalic acid in the preparation of Ag@Cu@Cu-MOF in Example 1, and the other conditions remain unchanged. The sample obtained is denoted as Ag@CuO@Cu-MOF-4. The performance test of the electrocatalytic reduction of carbon dioxide is consistent with that of Example 1.

[0090] Example 5:

[0091] In this example, 20 mg of 2-hydroxy-isonicotinic acid is used instead of terephthalic acid in the preparation of Ag@Cu@Cu-MOF in Example 1, and the other conditions remain unchanged. The sample obtained is denoted as Ag@CuO@Cu-MOF-5. The performance test of the electrocatalytic reduction of carbon dioxide is consistent with that of Example 1.

[0092] Example 6:

[0093] In this example, 20 mg of 2,3,6,7,10,11-hexahydroxytriphenyl is used instead of terephthalic acid in the preparation of Ag@Cu@Cu-MOF in Example 1, and the other conditions remain unchanged. The sample obtained is denoted as Ag@CuO@Cu-MOF-6. The performance test of the electrocatalytic reduction of carbon dioxide is consistent with that of Example 1.

[0094] Comparative Example 1:

[0095] Preparation of Cu2O nanoparticles: 180 mg of Cu(NO3)2·3H2O was dissolved in 10 mL of ethylene glycol, and the mixture was poured into a 50 mL three-necked flask. Ar gas was introduced as a protective gas, and stirring was performed for 30 min. Subsequently, heating was performed to 170°C for 10 min, at which time the solution was orange yellow. After the mixed solution was naturally cooled, washing was performed 4 times using a water-ethanol mixture, and then drying was performed in a vacuum drying box at 60°C for 8 h to obtain a Cu2O nanoparticle sample.

[0096] Preparation of CuO: 20 mg of the Cu2O sample was dispersed in 25 mL of ethanol, 5 mL of deionized water was added, and then 1 mL of concentrated ammonia was added under stirring conditions. Stirring was performed for 2 h, centrifugal separation was performed, washing was performed 4 times using a mixed solution of ethanol and water, and then drying was performed in a vacuum drying box at 60°C for 8 h to obtain a corresponding CuO sample.

[0097] Preparation of CuO@Cu-MOF: 20 mg of CuO was dispersed in a mixed solution of 10 mL of N,N-dimethylformamide, 1 mL of ethanol, and 1 mL of deionized water, 20 mg of terephthalic acid was then added, the mixture was uniformly mixed, and then the above dispersion was placed in a 50 mL hydrothermal kettle. Heating was performed at 120°C for 3 h. After natural cooling, centrifugal separation was performed, washing was performed 4 times using an ethanol-water mixture, and then drying was performed in a vacuum drying box at 60°C for 8 h to obtain a sample denoted as CuO@Cu-MOF-1 sample.

[0098] The performance of the electrocatalytic reduction of carbon dioxide was tested in accordance with Example 1.

[0099] Comparative Example 2:

[0100] The preparation conditions of Comparative Example 2 are consistent with the three steps of the preparation of Ag nanowires, the preparation of Ag@Cu2O, and the preparation of Ag@CuO in Example 1, and the obtained sample is Ag@CuO-1. The performance of the electrocatalytic reduction of carbon dioxide was tested in accordance with Example 1.

[0101] The catalyst obtained by the method of the present application was also tested:

[0102] The performance of the electrocatalytic reduction of carbon dioxide was tested in accordance with Example 1.

[0103] Results analysis

[0104] First, the catalyst was successfully obtained by the method of the present application, as shown in the following figures: Figure 2 In the figures, the diffraction peaks of Cu-MOF, Ag, and CuO can be seen. In Figure 1 , the SEM and SEM-EDS images of Example 1 and Example 2 show that the element distribution of the catalyst of the present application from inside to outside is Ag, Cu, and F element representing 2-fluoro-terephthalic acid is on the outside. Combined with Figure 1 and Figure 2 , it can be verified that the entire structure of the catalyst of the present application is Ag@CuO@Cu-MOF.

[0105] Figure 3 The results of the electroreduction of carbon dioxide of Example 1-Example 6 and Comparative Example 1-Comparative Example 2 in the H-type electrolytic cell are shown in the following table: Figure 3As can be seen, the embodiments 1-6 of the present application all have more excellent utilization of CO, and the selectivity of the catalysts of the embodiments 1-6 to C2 products is obviously higher, while the CO selectivity is lower. It is illustrated that the Ag@CuO@Cu-MOF structure of the obtained catalyst has excellent utilization efficiency to CO generated by Ag.

[0106] In summary, the obtained catalyst can exhibit higher selectivity to C2 products in the process of carbon dioxide electro-reduction, and can fully utilize CO.

[0107] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present application.

Claims

1. A carbon dioxide electroreduction catalyst characterized by, The catalyst is Ag@CuO@Cu-MOF, wherein Ag is silver, CuO is copper oxide, and Cu-MOF is a Cu metal framework; the CuO is coated on the surface of Ag, and the Cu-MOF is coated on the surface of CuO; The preparation method of the carbon dioxide electro-reduction catalyst comprises the following steps: S1: adding a copper precursor, polyvinylpyrrolidone, and Ag nanowires in an ethylene glycol solution under an inert atmosphere, uniformly mixing, heating and stirring, centrifuging, washing, and drying to obtain Ag@Cu2O; S2: dispersing Ag@Cu2O in a mixed solution of deionized water and ethanol, adding an inorganic base, and introducing oxygen for oxidation treatment, centrifuging, and drying to obtain an intermediate product Ag@CuO; S3: dispersing the intermediate product in a liquid reagent, adding an organic ligand, uniformly mixing, and then transferring to a hydrothermal kettle for heating, centrifuging, washing, and drying to obtain the catalyst; The copper precursor comprises one or more of copper nitrate trihydrate, copper acetate, copper sulfate, copper chloride, basic copper carbonate, and copper oxalate; The inorganic base comprises one or more of sodium hydroxide, potassium hydroxide, concentrated ammonia, and cesium hydroxide; The organic ligand comprises one or more of terephthalic acid, trimesic acid, 2-fluoroterephthalic acid, 2-hydroxyterephthalic acid, 2,3,6,7,10,11-hexahydroxytriphenyl, isonicotinic acid, 2-fluoroisonicotinic acid, and 2-hydroxyisonicotinic acid; The liquid reagent comprises one or more of water, N,N-dimethylformamide, ethanol, ethylene glycol, and acetamide; The inert atmosphere comprises one of nitrogen and argon.

2. The carbon dioxide electroreduction catalyst of claim 1, wherein, The Ag is Ag nanowires with a length of 1-100 μm and a cross-sectional diameter of 10-100 nm.

3. The carbon dioxide electroreduction catalyst of claim 1, wherein, The mass ratio of the copper precursor, polyvinylpyrrolidone, Ag nanowires, and ethylene glycol is 1-5:1-5:2-10:150-500.

4. The carbon dioxide electroreduction catalyst of claim 1, wherein, The heating and stirring temperature in S1 is 130-180°C, and the heating and stirring time is 5-30 min; the heating and stirring speed is 20-200 r / min. The drying condition in S1 is vacuum drying at 60-100°C for 8-12 h.

5. The carbon dioxide electroreduction catalyst of claim 1, wherein, The concentration of Ag@Cu2O in the mixed solution in S2 is 1-20 mg / mL. The molar ratio of deionized water, ethanol, and inorganic base in S2 is 100-200:10-100:0.1-100. The oxidation treatment time in S2 is 20-80 min, and the oxygen flow rate is 10-20 mL / min. The drying condition in S2 is vacuum drying at 60-100°C for 8-12 h.

6. The carbon dioxide electroreduction catalyst of claim 1, wherein, The concentration of the intermediate product in the liquid reagent in S3 is 2-10 mg / mL. The concentration of the organic ligand in the liquid reagent in S3 is 1-5 mg / mL.

7. The carbon dioxide electroreduction catalyst of claim 1, wherein, The heating temperature in S3 is 60-140°C, and the heating time is 1-12 h. The drying condition in S3 is vacuum drying at 60-100°C for 6-12 h.

8. Use of the carbon dioxide electroreduction catalyst of any one of claims 1-7 in carbon dioxide electroreduction.

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