Copper-based catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of carbon dioxide capture, and particularly relates to a copper-based catalyst and a preparation method and application thereof. The copper-based catalyst comprises a copper-containing oxide represented by a staggered nanowire structure and a second metal oxide grown on the surface of the copper-containing oxide, and the second metal oxide is island-shaped nanoparticles. The copper-based catalyst has the beneficial effects that the copper-based catalyst has rich heterostructures, the adsorption energy of an intermediate in the CO2 reduction process can be regulated and controlled, and a C-C coupling path is enhanced, so that the generation of a multi-carbon product is promoted.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon dioxide capture, and particularly relates to a copper-based catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Since the Industrial Revolution, the rapid increase in atmospheric carbon dioxide concentration has led to a significant greenhouse effect, resulting in a series of climate problems. In recent years, the world has joined hands to address the climate crisis, accelerated the deployment of renewable energy power generation, actively developed new technologies such as carbon capture, utilization and storage (CCUS) and hydrogen energy, and contributed to the reduction of carbon emissions in the whole society through the resource utilization of carbon dioxide (CO2). In terms of carbon utilization, benefiting from the development of renewable energy, the power-driven conversion and utilization of CO2 have received key attention. Compared with traditional thermal catalytic utilization methods, the power-driven conversion and utilization of CO2 can be carried out under mild conditions, the technology scale is controllable, the application scenarios are diverse, and with the cost reduction and efficiency improvement of renewable energy power generation technologies such as wind power and solar power generation, the commercial application of the power-driven conversion and utilization of CO2 has gradually become possible.

[0003] At present, researchers have carried out extensive and in-depth research on the technical direction of the electrochemical reduction of CO2 reaction (CO2RR). Significant progress has been made at the laboratory level by developing efficient catalysts, designing reaction systems and equipment. Currently, products such as formic acid and CO can be efficiently prepared, but the research on the preparation of multi-carbon products is relatively insufficient. Considering that the catalyst is the core factor for the efficient progress of the reaction, in order to achieve the conversion of CO2 into high-value multi-carbon products, corresponding efficient catalysts need to be developed. In the field of catalysis, scientific researchers have successfully constructed efficient nanocatalysts through methods such as nanoengineering, alloying, and heterostructures. Among them, the heterostructure can effectively combine two or more components, effectively regulate the catalytic surface and interface properties, improve the adsorption of key reaction intermediates, and thus enhance the selectivity and activity of specific products. Therefore, constructing a catalyst with a heterostructure is expected to improve the selectivity and activity of multi-carbon products in the electrochemical CO2 reduction reaction. Summary of the Invention

[0004] The present application provides a copper-based catalyst, a preparation method thereof, and an application thereof, aiming to solve the problem of insufficient selectivity and activity of multi-carbon products in the existing electrochemical CO2 reduction reaction.

[0005] In the first aspect of the present application, a copper-based catalyst is provided. The copper-based catalyst includes copper-containing oxides presented in an interlaced nanowire structure and second metal oxides grown on the surface of the copper-containing oxides, and the second metal oxides are in the form of island-shaped nanoparticles.

[0006] According to some embodiments of the copper-based catalyst of the present application, the second metal oxides include one or more of zirconium oxide, lanthanum oxide, cerium oxide, vanadium oxide, neodymium oxide, and niobium oxide.

[0007] In some embodiments of the copper-based catalyst according to the present application, the particle size of the copper-containing oxide is < 100 nm.

[0008] In some embodiments of the copper-based catalyst according to the present application, the particle size of the second metal oxide is < 10 nm.

[0009] The second aspect of the present application provides a method for preparing the copper-based catalyst according to the first aspect of the present application, comprising the following steps:

[0010] (1) Prepare a copper precursor

[0011] Mix a copper-containing compound, a complexing agent and water to obtain a first mixed solution, adjust the pH of the first mixed solution to be alkaline, and then sequentially perform centrifugal separation and drying treatment on the first mixed solution to obtain the copper precursor;

[0012] (2) Mix the copper precursor, a second metal compound and a solvent to obtain a second mixed solution, adjust the pH of the second mixed solution to be alkaline, and react to obtain a primary heterogeneous product;

[0013] (3) Calcinate the primary heterogeneous product under an inert atmosphere to obtain the copper-based catalyst.

[0014] In some embodiments of the method for preparing the copper-based catalyst according to the present application, in step (1), the copper-containing compound includes one or more of copper nitrate, copper chloride, copper bromide and hydrates of the above copper-containing compounds.

[0015] In some embodiments of the method for preparing the copper-based catalyst according to the present application, the concentration of the copper-containing compound in the first mixed solution is 10-100 mmol / L.

[0016] In some embodiments of the method for preparing the copper-based catalyst according to the present application, the complexing agent includes citric acid or ammonia water.

[0017] In some embodiments of the method for preparing the copper-based catalyst according to the present application, in the first mixed solution, the molar ratio of the complexing agent to the copper-containing compound is (1-3):1.

[0018] In some embodiments of the method for preparing the copper-based catalyst according to the present application, in step (1), the temperature of the mixing is 20-30 °C, and the time of the mixing is 5-50 min.

[0019] According to some embodiments of the preparation method of the copper-based catalyst of the present application, the regulator used to adjust the pH of the first mixed solution to alkaline is an aqueous solution of potassium hydroxide and / or an aqueous solution of sodium hydroxide; preferably, the concentration of the regulator is 0.8-1.2 mol / L; more preferably, the addition rate of the regulator is 0.5-2 ml / min.

[0020] According to some embodiments of the preparation method of the copper-based catalyst of the present application, adjusting the pH of the first mixed solution to alkaline means adjusting the pH of the first mixed solution to 9-10.5.

[0021] According to some embodiments of the preparation method of the copper-based catalyst of the present application, in step (2), the second metal compound includes one or more of zirconium nitrate, zirconium chloride, cerium nitrate, lanthanum nitrate, vanadium nitrate, neodymium nitrate, niobium nitrate and hydrates of the above metal compounds.

[0022] According to some embodiments of the preparation method of the copper-based catalyst of the present application, the solvent includes water and ethanol. Preferably, the volume ratio of water to ethanol in the solvent is (8-12):1.

[0023] According to some embodiments of the preparation method of the copper-based catalyst of the present application, the mass concentration of the copper precursor in the second mixed solution is 0.5-6 g / L.

[0024] According to some embodiments of the preparation method of the copper-based catalyst of the present application, in the second mixed solution, the addition amount of the second metal compound is 1%-30% of the mass of the copper precursor.

[0025] According to some embodiments of the preparation method of the copper-based catalyst of the present application, the regulator used to adjust the pH of the second mixed solution includes a mixed solution of ammonia water and an alkali solution. Preferably, the alkali solution includes an aqueous solution of potassium hydroxide and / or an aqueous solution of sodium hydroxide; more preferably, the concentration of the ammonia water is 0.01-0.03 mol / L, the concentration of the alkali solution is 0.8-1.2 mol / L; further preferably, the addition rate of the regulator is 0.5-2 ml / min.

[0026] According to some embodiments of the preparation method of the copper-based catalyst of the present application, adjusting the pH of the second mixed solution to alkaline means adjusting the pH of the second mixed solution to 9-10.

[0027] According to some embodiments of the preparation method of the copper-based catalyst of the present application, in step (2), the reaction is a microwave reaction.

[0028] According to some embodiments of the preparation method of the copper-based catalyst of the present application, the power of the microwave reaction is 150-400 W.

[0029] According to some embodiments of the preparation method of the copper-based catalyst of the present application, the time of the microwave reaction is 5-20 min.

[0030] According to some embodiments of the preparation method of the copper-based catalyst of the present application, in step (3), the calcination temperature is 400-600 °C, and the calcination time is 1-8 h.

[0031] According to some embodiments of the preparation method of the copper-based catalyst of the present application, during the calcination process, the heating rate of the temperature is 5-20 °C / min.

[0032] The third aspect of the present application provides an application of the copper-based catalyst described in the first aspect of the present application or the copper-based catalyst obtained by the preparation method described in the second aspect of the present application in the electrochemical reduction of carbon dioxide to prepare multi-carbon products.

[0033] According to some embodiments of the application of the present application, the multi-carbon products include carbon-containing compounds with the number of carbon atoms greater than or equal to 2.

[0034] According to some embodiments of the application of the present application, the multi-carbon products include one or more of ethylene, ethanol, acetic acid, propanol, propane, and propylene.

[0035] The beneficial effects of the present application include: the copper-based catalyst described in the present application has a rich heterogeneous structure, which helps to regulate the adsorption energy of intermediates in the CO2 reduction process, enhance the C-C coupling path, and promote the formation of multi-carbon products. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is the TEM image of the copper-based catalyst described in Example 1 of the present application;

[0037] Figure 2 It is the TEM image of the copper-based catalyst described in Comparative Example 1 of the present application;

[0038] Figure 3 It is the comparison chart of the Faraday efficiency of the copper-based catalysts described in Example 1 and Comparative Example 1 of the present application in the CO2 electroreduction reaction. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The embodiments of the present invention are described in detail below. The examples are exemplary and are intended to explain the present invention, but should not be construed as a limitation of the present invention.

[0040] In the present invention, terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0041] The embodiments of the present application provide a copper-based catalyst. The copper-based catalyst includes copper-containing oxides presented in an interlaced nanowire structure and second metal oxides grown on the surface of the copper-containing oxides, and the second metal oxides are in the form of island-shaped nanoparticles. The copper-containing oxides contained in the copper-based catalyst of the present application have an interlaced nanowire structure, and the copper-containing compound presenting a three-dimensional network structure provides a good electron transport environment for the catalyst, effectively enhancing the conductivity of the catalyst; the second metal oxides form a heterostructure with the copper oxides, which helps to regulate the adsorption energy of intermediates in the CO2 reduction process, enhance the C-C coupling path, and promote the formation of multi-carbon products.

[0042] In some embodiments of the present application, the second metal oxides include one or more of zirconium oxide, lanthanum oxide, cerium oxide, vanadium oxide, neodymium oxide, and niobium oxide.

[0043] In some embodiments of the present application, the particle size of the copper-containing oxides < 100 nm; for example, 98 nm, 95 nm, 90 nm, 86 nm, 80 nm, 78 nm, 70 nm, 69 nm, 63 nm, 58 nm, 50 nm, etc.

[0044] In some embodiments of the present application, the particle size of the second metal oxides < 10 nm; for example, 9 nm, 8 nm, 7 nm, 6 nm, 5 nm, etc.

[0045] The embodiments of the present application also provide a preparation method of the copper-based catalyst described in the first aspect of the present application, including the following steps:

[0046] (1) Prepare a copper precursor

[0047] Mix a copper-containing compound, a complexing agent, and water to obtain a first mixed solution, adjust the pH of the first mixed solution to be alkaline, and then perform centrifugal separation and drying treatment on the first mixed solution in sequence to obtain the copper precursor;

[0048] (2) Mix a copper precursor, a second metal compound, and a solvent to obtain a second mixed solution. Adjust the pH of the second mixed solution to be alkaline and react to obtain a primary heterogeneous product.

[0049] (3) Calcinate the primary heterogeneous product under an inert atmosphere to obtain the copper-based catalyst.

[0050] The preparation method of the copper-based catalyst described in this application uses easily available raw materials and does not involve complex compounds. The preparation process is simple to operate and has great potential in large-scale catalyst preparation. The obtained catalytic material has good activity and stability.

[0051] In some embodiments of this application, in step (1), the copper-containing compound includes one or more of copper nitrate, copper chloride, copper bromide, and hydrates of the above copper-containing compounds.

[0052] In some embodiments of this application, the concentration of the copper-containing compound in the first mixed solution is 10-100 mmol / L; for example, 10 mmol / L, 20 mmol / L, 32 mmol / L, 43 mmol / L, 56 mmol / L, 67 mmol / L, 73 mmol, 82 mmol / L, 91 mmol, 100 mmol / L, etc.

[0053] In some embodiments of this application, the complexing agent includes citric acid or ammonia water.

[0054] In some embodiments of this application, in the first mixed solution, the molar ratio of the complexing agent to the copper-containing compound is (1-3):1; for example, 1:1, 1.2:1, 2:1, 2.6:1, 3:1, etc. Within this molar ratio range, sufficient complexation of copper ions with the complexing agent can be achieved, and good dispersion of copper ions can be realized at the microscopic level, laying a foundation for the formation of hydroxides.

[0055] In some embodiments of this application, in step (1), the temperature of the mixing is 20-30 °C; for example, 20 °C, 22 °C, 25 °C, 28 °C, 30 °C, etc., and the mixing time is 5-50 min; for example, 5 min, 8 min, 12 min, 18 min, 20 min, 30 min, 40 min, 50 min, etc.

[0056] In some embodiments of the present application, the regulator used to adjust the pH of the first mixed solution to alkaline is an aqueous solution of potassium hydroxide and / or an aqueous solution of sodium hydroxide; preferably, the concentration of the regulator is 0.8 - 1.2 mol / L; more preferably, the addition rate of the regulator is 0.5 - 2 ml / min, such as 0.5 ml / min, 0.8 ml / min, 1.2 ml / min, 1.5 ml / min, 2 ml / min, etc. Selecting this addition rate can ensure the formation rate of copper hydroxide and avoid the formation of bulk materials due to excessive growth.

[0057] In some embodiments of the present application, adjusting the pH of the first mixed solution to alkaline means adjusting the pH of the first mixed solution to 9 - 10.5, such as pH = 9, pH = 10, pH = 10.5, etc. Within this pH range, copper hydroxide with the characteristics of a nanowire structure can be effectively grown.

[0058] In some embodiments of the present application, in step (2), the second metal compound includes one or more of zirconium nitrate, zirconium chloride, cerium nitrate, lanthanum nitrate, vanadium nitrate, neodymium nitrate, niobium nitrate, and hydrates of the above metal compounds. If a simple copper nanowire network structure is used as a catalyst, the selectivity and activity for multi-carbon products during the CO2 electroreduction process are insufficient. Introducing the second metal compound will form a second element hydroxide on the surface of copper hydroxide, and then jointly form a heterostructure, which, as a catalyst for CO2 electroreduction, will effectively regulate the intermediates in the reaction process, promote the C - C coupling process, and improve the catalytic effect of multi-carbon products.

[0059] In some embodiments of the present application, the solvent includes water and ethanol. Preferably, the volume ratio of water to ethanol in the solvent is (8 - 12):1, such as 8:1, 9:1, 10:1, 12:1, etc.

[0060] In some embodiments of the present application, the mass concentration of the copper precursor in the second mixed solution is 0.5 - 6 g / L, such as 0.5 g / L, 1.2 g / L, 2.3 g / L, 3.2 g / L, 4.5 g / L, 5 g / L, 5.6 g / L, 6 g / L, etc.

[0061] In some embodiments of the present application, in the second mixed solution, the addition amount of the second metal compound is 1% - 30% of the mass of the copper precursor; such as 1%, 5%, 8%, 12%, 18%, 21%, 26%, 30%, etc.

[0062] In some embodiments of the present application, the regulator used to adjust the pH of the second mixed solution includes a mixed solution of ammonia water and an alkaline solution.

[0063] In some embodiments of the present application, the lye includes an aqueous potassium hydroxide solution and / or an aqueous sodium hydroxide solution; more preferably, the concentration of the ammonia water is 0.01 - 0.03 mol / L, and the concentration of the lye is 0.8 - 1.2 mol / L.

[0064] In some embodiments of the present application, the addition rate of the regulator is 0.5 - 2 ml / min; for example, 0.5 ml / min, 1.2 ml / min, 1.5 ml / min, 2 ml / min, etc. Selecting the addition rate of the regulator within this range can effectively control the formation rate of the second metal element hydroxide and control the growth size of the primary heterogeneous product.

[0065] In some embodiments of the present application, adjusting the pH of the second mixed solution to alkaline means adjusting the pH of the second mixed solution to 9 - 10, for example, pH = 9, pH = 9.5, pH = 10, etc. Controlling the pH within this range can effectively control the growth of the second metal element hydroxide and avoid agglomeration.

[0066] In some embodiments of the present application, in step (2), the reaction is a microwave reaction. Using a microwave reaction can make the reaction conditions more controllable and the obtained products have strong consistency.

[0067] In some embodiments of the present application, the power of the microwave reaction is 150 - 400 W, for example, 150 W, 200 W, 260 W, 370 W, 400 W, etc. Controlling the reaction power within this range can effectively control the formation of the copper - second metal element precursor.

[0068] In some embodiments of the present application, the time of the microwave reaction is 5 - 20 min, for example, 5 min, 10 min, 15 min, 20 min, etc.

[0069] In some embodiments of the present application, in step (3), the calcination temperature is 400 - 600 °C, for example, 400 °C, 450 °C, 480 °C, 500 °C, 550 °C, 600 °C, etc., and the calcination time is 1 - 8 h; for example, 1 h, 2 h, 4 h, 5 h, 6 h, 8 h, etc. Selecting this temperature range for calcination is beneficial to the formation of a stable heterogeneous structure and avoids the collapse of the microstructure caused by too high a temperature.

[0070] In some embodiments of the present application, during the calcination process, the heating rate of the temperature is 5 - 20 °C / min, for example, 5 °C / min, 8 °C / min, 10 °C / min, 13 °C / min, 15 °C / min, 18 °C / min, 20 °C / min, etc.

[0071] The embodiments of the present application also provide an application of the copper-based catalyst described in the first aspect of the present application or the copper-based catalyst obtained by the preparation method described in the second aspect of the present application in the electrochemical reduction of carbon dioxide to prepare multi-carbon products.

[0072] In some embodiments of the present application, the multi-carbon products include carbon-containing compounds with the number of carbon atoms greater than or equal to 2.

[0073] In some embodiments of the present application, the multi-carbon products include one or more of ethylene, ethanol, acetic acid, propanol, propane, and propylene.

[0074] In some embodiments of the present application, the copper-based catalyst described in the first aspect of the present application or the copper-based catalyst obtained by the preparation method described in the second aspect of the present application is dissolved in a polar solvent, and the concentration of the copper-based catalyst can be 0.5-25 g / L. After being uniformly dispersed by low-temperature ultrasonic treatment, an ionomer solution is added, and then ultrasonic dispersion is carried out again for 5-60 min to form a catalyst solution. The catalyst solution is loaded on the surface of a porous substrate by using ultrasonic spraying, spin coating, or transfer printing methods, and the loading amount can be 0.2-5 mg / cm 2 , to obtain a gas diffusion electrode.

[0075] In some embodiments of the present application, the polar solvent includes one or more of methanol, ethanol, acetone, and isopropanol.

[0076] In some embodiments of the present application, the polymer solution includes perfluorosulfonic acid polymer (PFSA) solution, polyaryl solution, polyether solution, polyolefin-based anion exchange resin solution, etc.

[0077] In some embodiments of the present application, the mass ratio of the ionomer to the copper-based catalyst is 0.1-0.35:1.

[0078] In some embodiments of the present application, the porous substrate includes hydrophobic carbon paper, carbon cloth, nickel felt, or titanium felt, etc.

[0079] In some embodiments of the present application, the above gas diffusion electrode is used as the cathode, a foam nickel, nickel felt, or iridium oxide-supported (nickel, titanium, stainless steel) felt / mesh is used as the counter electrode, and a neutral or alkaline solution is used as the electrolyte. A carbon dioxide gas stream is introduced into the cathode side to carry out the CO2 electroreduction reaction in a two-electrode or three-electrode system (Hg / HgO is used as the reference electrode).

[0080] In some embodiments of the present application, the electrolyte includes 0.01-3 mol / L KOH or 0.01-3 mol / L NaOH, or 0.1-1 mol / L KX (X = Cl, Br, I) solution.

[0081] Example 1

[0082] A preparation method of a copper-based catalyst, comprising the following steps:

[0083] (1) At a temperature of 25 °C, weigh 800 mg of copper chloride dihydrate and add it to 100 mL of deionized water. Continuously stir with a magnetic stirrer. After complete dissolution, add 210 mg of ammonia water. Then stir for 10 min, and then dropwise add 1 mol / L KOH solution at a rate of 1.2 mL / min until the pH of the solution reaches 9.8. Continue stirring for 15 min. Obtain the product by centrifugation, and wash the product with deionized water until the neutral pH = 7. Freeze-dry to obtain a copper precursor;

[0084] Weigh 500 mg of the copper precursor and disperse it in 150 mL of a water-alcohol mixed solution (volume ratio of water to alcohol is 10:1). Subsequently, add 120 mg of zirconium nitrate. After stirring and dissolving, use a 0.01 mol / L ammonia water + 1 mol / L KOH mixed solution to adjust the pH of the solution to 9, with a dropping rate of 1.0 mL / min. Then place the solution in a microwave reactor and react for 8 min under stirring conditions at a power of 220 W for 8 min. Subsequently, centrifuge the product and wash the product with deionized water until it is neutral (pH = 7). After freeze-drying, obtain a primary heterostructure;

[0085] (3) Place the primary heterostructure under an argon atmosphere. In a tubular furnace, heat from room temperature (20 °C) to 500 °C at a rate of 10 °C / min, hold for 2 h, and then cool to room temperature at a rate of 20 °C / min to obtain a copper-zirconium (Cu-Zr) catalyst with a heterostructure.

[0086] Example 2

[0087] The difference between the preparation method of the copper-based catalyst described in Example 2 and that in Example 1 is only that the pH of the first mixed solution is adjusted to 9 in the copper-based catalyst described in Example 2, and the rest of the operations are the same as those in Example 1.

[0088] Example 3

[0089] The difference between the preparation method of the copper-based catalyst described in Example 3 and that in Example 1 is only that the pH of the first mixed solution is adjusted to 10.5 during the preparation of the copper-based catalyst described in Example 3, and the rest of the operations are the same as those in Example 1.

[0090] Example 4

[0091] The difference between the preparation method of the copper-based catalyst described in Example 4 and that in Example 1 is only that the second element salt used during the preparation of the copper-based catalyst described in Example 4 is cerium nitrate, and the rest of the operations are the same as those in Example 1.

[0092] Example 5

[0093] The preparation method of the copper-based catalyst described in Example 5 is different from that in Example 1 only in that lanthanum nitrate is used as the second element salt in the preparation process of the copper-based catalyst described in Example 5, and the remaining operations are the same as those in Example 1.

[0094] Example 6

[0095] The preparation method of the copper-based catalyst described in Example 6 is different from that in Example 1 only in that vanadium nitrate is used as the second element salt in the preparation process of the copper-based catalyst described in Example 6, and the remaining operations are the same as those in Example 1.

[0096] Example 7

[0097] The preparation method of the copper-based catalyst described in Example 7 is different from that in Example 1 only in that the power of the microwave reaction is 150 W in the preparation process of the copper-based catalyst described in Example 7, and the remaining operations are the same as those in Example 1.

[0098] Example 8

[0099] The preparation method of the copper-based catalyst described in Example 8 is different from that in Example 1 only in that the power of the microwave reaction is 300 W in the preparation process of the copper-based catalyst described in Example 8, and the remaining operations are the same as those in Example 1.

[0100] Example 9

[0101] The preparation method of the copper-based catalyst described in Example 9 is different from that in Example 1 only in that the power of the microwave reaction is 400 W in the preparation process of the copper-based catalyst described in Example 9, and the remaining operations are the same as those in Example 1.

[0102] Example 10

[0103] The preparation method of the copper-based catalyst described in Example 10 is different from that in Example 1 only in that the calcination temperature is 400 °C in the preparation process of the copper-based catalyst described in Example 10, and the remaining operations are the same as those in Example 1.

[0104] Example 11

[0105] The preparation method of the copper-based catalyst described in Example 11 is different from that in Example 1 only in that the calcination temperature is 450 °C in the preparation process of the copper-based catalyst described in Example 11, and the remaining operations are the same as those in Example 1.

[0106] Example 12

[0107] The preparation method of the copper-based catalyst described in Example 12 is different from that in Example 1 only in that the calcination temperature is 600 °C in the preparation process of the copper-based catalyst described in Example 12, and the remaining operations are the same as those in Example 1.

[0108] Comparative Example 1

[0109] The preparation method of the copper-based catalyst described in Comparative Example 1 is different from that of Example 1 only in that no second element salt is added during the preparation of the copper-based catalyst described in Comparative Example 1, and the remaining operations are the same as those in Example 1.

[0110] Comparative Example 2

[0111] The preparation method of the copper-based catalyst described in Comparative Example 2 is different from that of Example 1 only in that the primary heterogeneous product is calcined in an air atmosphere during the preparation of the copper-based catalyst described in Comparative Example 2, and the remaining operations are the same as those in Example 1.

[0112] Performance study of the copper-based catalysts described in Examples 1-12 and Comparative Examples 1-2 of the present application in the electroreduction of carbon dioxide to isopropanol.

[0113] 1. Test method

[0114] 100 mg of the copper-based catalysts prepared in Examples 1-12 and Comparative Examples 1-2 were respectively dissolved in 20 mL of isopropanol. After low-temperature ultrasonic dispersion for 5 min, 300 mg of Sustainion XA-9 ionomer solution (5 wt%) (purchased from Dioxide, USA) was added and ultrasonicated at low temperature for 30 min to form catalyst ink. The working electrodes were obtained by ultrasonic spraying and loaded onto hydrophobic carbon paper. The loading amount of the above copper-based catalysts was 2.5 mg / cm 2 .

[0115] In a flowing electrolytic cell system, the above working electrode was used as the cathode (electrode area 2 cm 2 ), an iridium oxide-coated titanium mesh electrode was used as the anode (electrode area 2 cm 2 ), a Hg / HgO electrode was used as the reference electrode, a Sustainion-X37GradeT anion exchange membrane was used to isolate the anode and cathode, 1 mol / L KOH solution was used as the electrolyte (flow rate 50 mL / min), high-purity CO2 gas (99.99%) was introduced into the gas side of the cathode at a flow rate of 10 ml / min, and the test was carried out in the range of -0.6 to -1.2 V (relative to the reversible hydrogen electrode). The test performance is shown in Table 1.

[0116] Table 1

[0117]

[0118] As can be seen from Table 1, factors such as the pH of the first mixed solution, the types of elements of the second metal compound, the power of the microwave reaction, and the calcination temperature have certain effects on the selectivity (Faraday efficiency) and activity (partial current density) of the copper-based catalyst for multi-carbon products in the CO2 electroreduction reaction. However, within the scope of the patent implementation, the overall comparison remains at a relatively high level (Faraday efficiency > 74.0%, partial current density > 820 mA / cm 2 ), significantly superior to Comparative Example 1 (without adding the second metal element) and Comparative Example 2 (calcining the primary product in air). It is proved that the introduction of the second metal element described in this patent to form a copper-based catalyst with a heterostructure has significantly better catalytic performance in the electrochemical reduction of CO2 to multi-carbon products than the copper-based catalyst obtained by calcining the primary product under inert conditions. Therefore, the method described in this patent can bring significant beneficial effects, indicating that the method described in this patent has considerable feasibility.

[0119] The TEM images of the copper-based catalysts described in Example 1 and Comparative Example 1 of this application are respectively as Figure 1 and Figure 2 shown.

[0120] From Figure 1 and Figure 2 it can be seen that: the copper-based catalyst described in this application shows a nanostructure of staggered nanowires. The particle size of the copper oxide is between 20 - 60 nm, forming a basic three-dimensional network structure. After introducing the second metal element, island-like particles with a size of 2 - 5 nm, namely the oxides of the second metal element, grow on the surface of the nanowires, forming a rich heterostructure with the copper oxide nanowires.

[0121] The comparison chart of the Faraday efficiency of the copper-based catalysts described in Example 1 and Comparative Example 1 of this application in the CO2 electroreduction reaction is as Figure 3 shown.

[0122] From Figure 3 it can be seen that: within the test range, the selectivity of the copper-based catalyst described in this application for multi-carbon products is significantly higher than that of the copper catalyst obtained in Comparative Example 1; at an applied potential of -1.05 V (relative to the reversible hydrogen electrode), the Faraday efficiencies of both reach the peak, and the Faraday efficiency of the copper-based catalyst described in this application for multi-carbon products is close to twice that of the copper catalyst.

[0123] Although the above embodiments have been shown and described, it can be understood that the above embodiments are exemplary and should not be construed as limitations of the present invention. Any changes, modifications, substitutions, and variations made by those of ordinary skill in the art to the above embodiments are within the protection scope of the present invention.

Claims

1. A copper-based catalyst, characterized in that The copper-based catalyst comprises a copper-containing oxide in a staggered nanowire structure and a second metal oxide grown on the surface of the copper-containing oxide, wherein the second metal oxide is in the form of island-shaped nanoparticles.

2. The copper-based catalyst according to claim 1, characterized in that The second metal oxide includes one or more of zirconium oxide, lanthanum oxide, cerium oxide, vanadium oxide, neodymium oxide and niobium oxide; And / or, the particle size of the copper oxide-containing particles is less than 100 nm; And / or, the particle size of the second metal oxide is less than 10 nm.

3. The method for preparing the copper-based catalyst according to any one of claims 1 to 2, characterized in that: The following steps are involved: (1) Preparation of copper precursor Mixing a copper-containing compound, a complexing agent and water to obtain a first mixed solution, adjusting the pH of the first mixed solution to alkaline, and then centrifuging and drying the first mixed solution in sequence to obtain the copper precursor; (2) mixing a copper precursor, a second metal compound and a solvent to obtain a second mixed solution, adjusting the pH of the second mixed solution to alkaline, and reacting to obtain a primary heterogeneous product; (3) calcining the primary heterogeneous product under an inert atmosphere to obtain the copper-based catalyst.

4. The method for preparing a copper-based catalyst according to claim 3, characterized in that: In step (1), the copper-containing compound includes one or more of copper nitrate, copper chloride, copper bromide and hydrates of the above copper-containing compounds; And / or, the concentration of the copper compound in the first mixed solution is 10-100 mmol / L; and / or, the complexing agent comprises citric acid or ammonia; And / or, in the first mixed solution, the molar ratio of the complexing agent to the copper-containing compound is (1-3):

1.

5. The method for preparing a copper-based catalyst according to claim 3, characterized in that: In step (1), the mixing temperature is 20-30° C. and the mixing time is 5-50 min; And / or, the regulator used to adjust the pH of the first mixed solution to alkalinity is a potassium hydroxide aqueous solution and / or a sodium hydroxide aqueous solution; preferably, the concentration of the regulator is 0.8-1.2 mol / L; more preferably, the addition rate of the regulator is 0.5-2 ml / min; And / or, adjusting the pH of the first mixed solution to alkaline is adjusting the pH of the first mixed solution to 9-10.

5.

6. The method for preparing a copper-based catalyst according to claim 3, characterized in that: In step (2), the second metal compound includes one or more of zirconium nitrate, zirconium chloride, cerium nitrate, lanthanum nitrate, vanadium nitrate, neodymium nitrate and niobium nitrate and hydrates of the above metal compounds; And / or, the solvent includes water and ethanol, preferably, the volume ratio of water to ethanol in the solvent is (8-12):

1.

7. The method for preparing a copper-based catalyst according to claim 3, characterized in that: The mass concentration of the copper precursor in the second mixed solution is 0.5-6 g / L; and / or, in the second mixed solution, the amount of the second metal compound added is 1%-30% of the mass of the copper precursor; And / or, the regulator used to adjust the pH of the second mixed solution includes a mixture of ammonia water and alkali solution, preferably, the alkali solution includes potassium hydroxide aqueous solution and / or sodium hydroxide aqueous solution; more preferably, the concentration of ammonia water is 0.01-0.03 mol / L, and the concentration of alkali solution is 0.8-1.2 mol / L; further preferably, the addition rate of the regulator is 0.5-2 ml / min; And / or, adjusting the pH of the second mixed solution to alkaline is adjusting the pH of the second mixed solution to 9-10.

8. The method for preparing a copper-based catalyst according to claim 3, characterized in that: In step (2), the reaction is a microwave reaction; Preferably, the power of the microwave reaction is 150-400W; Preferably, the microwave reaction time is 5-20 min.

9. The method for preparing a copper-based catalyst according to claim 3, characterized in that: In step (3), the calcination temperature is 400-600° C. and the calcination time is 1-8 h; And / or, during the calcination process, the temperature rising rate is 5-20°C / min.

10. Use of the copper-based catalyst according to any one of claims 1 to 2 or the copper-based catalyst obtained by the preparation method according to any one of claims 3 to 9 in the electrochemical reduction of carbon dioxide to prepare multi-carbon products; Preferably, the multi-carbon product includes carbon-containing compounds having a carbon number greater than or equal to 2; more preferably, the multi-carbon product includes one or more of ethylene, ethanol, acetic acid, propanol, propane and propylene.

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