Composite catalyst for preparing synthesis gas with accurate and controllable proportion through electrolysis of carbon dioxide as well as preparation method and application of composite catalyst

Abstract

The invention discloses a composite catalyst for preparing synthesis gas with an accurate and controllable proportion through electrolysis of carbon dioxide as well as a preparation method and application of the composite catalyst. The composite catalyst is prepared by compounding a component I and a component II in a physical mixing manner. The component I is nitrogen-doped carbon-supported iron-based metal and is used as a catalyst unit for preferentially separating out CO; and the component II is nitrogen-doped carbon-supported molybdenum or tungsten and is used as a preferential hydrogen evolution unit. The composite catalyst provided by the invention adopts a convenient physical mixing method, the preparation method is simple and efficient, and electron interaction between double active sites of a catalyst prepared by a traditional co-loading method and non-CO byproducts such as formic acid generated by the electron interaction can be avoided through space obstruction. By simply adjusting the mass ratio of the component I to the component II, the ratio of the synthesis gas can be accurately regulated and controlled, so that the synthesis gas meets different ratio requirements of downstream industrial applications (such as methanol and dimethyl ether synthesis), and the synthesis gas is high in yield, good in stability and wide in application prospect.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical catalysis and carbon dioxide resource utilization technology, specifically relating to a composite catalyst for the precise and controllable ratio of carbon dioxide electroreduction to syngas, its preparation method, and its application. Background Technology

[0002] Electrocatalytic carbon dioxide reduction (CO2 reduction) has attracted widespread attention in recent years as an effective way to store renewable energy in the form of chemical bonds, while reducing greenhouse gas emissions and achieving carbon resource recycling. However, this technology currently faces challenges such as low product yield and poor Faraday efficiency. In particular, when the products are liquid products such as formic acid, ethanol, and methanol, the process of separating these products from the electrolyte often makes the electrocatalytic CO2 reduction pathway economically unfeasible (Adv. Sci., 2018, 5, 1700275, Adv. Energy Mater., 2020, 10, 1902106). In contrast, the utilization pathway of reducing carbon dioxide to gaseous products (such as carbon monoxide) is more feasible for industrial applications because it does not require complex product separation processes. Currently, most research focuses on the highly selective reduction of carbon dioxide to carbon monoxide and efforts to suppress the hydrogen evolution reaction as a side reaction. However, since carbon dioxide electrolysis is typically carried out in an aqueous electrolyte, hydrogen removal from the water is almost unavoidable (Chem. Soc. Rev., 2024, 53, 5149-5189). On the other hand, syngas is a key feedstock for the production of organic chemicals, fertilizers, fuels, and solvents in Fischer-Tropsch synthesis and other conversion processes.

[0003] Since hydrogen evolution reaction is unavoidable in electrocatalytic carbon dioxide reduction, utilizing this competing side reaction instead of inhibiting it, and combining electrocatalytic carbon dioxide reduction with hydrogen evolution to produce syngas, has significant value and promising application prospects for generating electricity using renewable energy under environmental conditions. To date, although researchers have explored various catalysts, including metals, metal oxides, metal sulfides, nano-carbon, and molecular catalysts, for the electrocatalytic reduction of carbon dioxide to produce syngas, problems remain regarding low activity, low selectivity, and difficulty in precisely adjusting the syngas ratio. In particular, different downstream applications require specific syngas ratios; for example, methanol synthesis requires approximately 0.5:1, dimethyl ether / acetic acid synthesis and hydroformylation require approximately 1:1, Fischer-Tropsch synthesis requires approximately 0.5-1:1, and polycarbonate synthesis requires 2:1.

[0004] Currently, bifunctional catalysts with two active sites have attracted widespread attention in order to obtain syngas with adjustable ratios. The design idea is that one site selectively promotes the conversion of carbon dioxide to carbon monoxide, while the other site promotes hydrogen evolution (Sci. Adv., 2021, 7, eabl4915, Angew. Chem. Int. Ed., 2020, 59, 3033-3037). However, existing bifunctional catalysts usually adopt a co-loading method of loading two active sites on the same support. This method has significant drawbacks: (1) Limited control range and potential dependence: Although a wide range of syngas ratios has been achieved, the specific ratio required for downstream synthesis is often only obtainable at a specific applied potential, and the syngas production rate is usually not the highest at that potential. That is, the potential to obtain a specific syngas ratio (such as 2, 1, and 0.5) is often not the optimal potential to maximize syngas production. (2) Difficulty in optimizing active sites: When loading two active sites on a support to prepare bifunctional catalysts, it is difficult to simultaneously optimize the catalytic performance of the two sites. (3) Interactions may occur between the two sites on the carrier, which may lead to the formation of non-CO carbon products (such as hydrocarbons, alcohols, etc.), thereby increasing the complexity and energy consumption of the product separation process, thus limiting its application.

[0005] Therefore, there is an urgent need to develop a high-efficiency and low-cost catalyst and preparation method for producing syngas by carbon dioxide electrolysis, so as to avoid the adverse interactions that may be caused by the interaction during the preparation of bifunctional catalysts, thereby solving the problems of low syngas production efficiency and difficulty in precise control of ratio in the production of syngas by carbon dioxide electrolysis. Summary of the Invention

[0006] To address the aforementioned problems, this invention discloses a composite catalyst for precisely controlled syngas production via carbon dioxide electrolysis, its preparation method, and its applications. Inspired by oxide-zeolite composite catalysts used in Fischer-Tropsch synthesis of low-carbon olefins, this invention completely abandons the design concept and preparation process of existing bifunctional catalysts for carbon dioxide electrolysis to syngas. Through extensive experimental trials, a novel approach was proposed: physically mixing a preferential CO evolution unit (PCE) and a preferential hydrogen evolution unit (PHE). This resulted in the design and preparation of a composite catalyst (PCE-PHE) for precisely controlled syngas production via carbon dioxide electrolysis. Since high hydrogen generation rates are easily achievable, the key to improving syngas yield lies in increasing the CO generation rate. Therefore, the core of developing a highly efficient PCE-PHE syngas catalyst lies in the design of the PCE unit. This research abandons the design limitation of traditional carbon dioxide electrolysis catalysts, which must suppress hydrogen evolution side reactions. The research focus is entirely on maximizing the activity of the PCE catalytic unit in carbon dioxide electrolysis to CO production, allowing for the generation of hydrogen during the process, thereby maximizing the syngas yield. However, existing bifunctional catalysts containing two sites (CO evolution and hydrogen evolution) cannot avoid interactions between the two sites during preparation because both sites are supported on a single support, and thus cannot optimize the catalytic performance of both sites. Our disclosed catalyst and preparation method, on the other hand, design, prepare, and optimize the two catalytic units (preferential CO evolution and preferential hydrogen evolution) separately, achieving their respective optimizations. Furthermore, our catalyst can be easily optimized by adjusting the mass ratio of components I and II according to their respective CO2 electrolysis catalytic performance and the specific application scenario of syngas; existing bifunctional catalysts cannot achieve this because both sites are manufactured simultaneously. Our composite catalyst and preparation method, through physical barrier, avoids potential adverse interactions between the two sites (CO evolution and hydrogen evolution) during catalyst preparation and application.

[0007] In summary, the composite catalyst provided by this invention enables precise and controllable production of syngas from carbon dioxide electrolysis, achieving high syngas yield, selectivity, and stability. The preparation method of the composite catalyst for precisely controllable syngas production from carbon dioxide electrolysis provided by this invention is simple, uses inexpensive and readily available raw materials, and has significant industrial potential.

[0008] The technical solution of the present invention is as follows:

[0009] A method for preparing a composite catalyst for precisely controllable proportioning of syngas produced by carbon dioxide electrolysis, characterized by the following steps:

[0010] Step 1: Grind and mix iron-based metal salts, carbon source, nitrogen source and pore-forming agent to obtain solid powder A. Calcine solid powder A in an inert atmosphere to obtain component I.

[0011] Step 2: Grind and mix molybdenum salt (or tungsten salt), carbon source, nitrogen source and pore-forming agent to obtain solid powder B. Calcine solid powder B in an inert atmosphere to obtain component II.

[0012] Step 3: Physically mix component I prepared in step 1 and component II prepared in step 1 to obtain the composite catalyst.

[0013] In this invention, the mass ratio of iron-based metal salt, carbon source, nitrogen source and pore-forming agent in step 1 is 1:4-500:5-300:5-300 (preferably 1:8-20:28-116:22-133), and the mass ratio of molybdenum salt (or tungsten) salt, carbon source, nitrogen source and pore-forming agent in step 1 is 1:2-500:5-300:2-300 (preferably 1:12-42:55-218:60-250).

[0014] In this invention, the inert atmosphere in steps 1 and 2 is nitrogen or argon, the flow rate is 5 to 250 ml / min (preferably 10 to 70 ml / min), the calcination temperature is 300 to 1000℃ (preferably 700 to 950℃), and the calcination time is 30 to 300 min (preferably 60 to 180 min).

[0015] In this invention, the iron-based metal salt mentioned in step 1 is selected from ferric acetylacetone, ferric nitrate, ferric acetate, ferric chloride, ferric sulfate, cobalt nitrate, cobalt acetylacetone, cobalt acetate, cobalt chloride, cobalt sulfate, nickel nitrate, nickel acetate, nickel chloride, nickel sulfate, and nickel acetylacetone. The molybdenum (or tungsten) salt mentioned in step 2 is selected from ammonium molybdate, sodium molybdate, ammonium tungstate, and sodium tungstate. The carbon source mentioned in steps 1 and 2 is selected from glucose, citric acid, and carboxymethyl cellulose; the nitrogen source is selected from melamine, urea, dicyandiamide, and polyaniline; and the pore-forming agent is selected from ammonium carbonate, ammonium bicarbonate, ammonium chloride, and ammonium nitrate.

[0016] In this invention, the mass ratio of component I and component II in step 3 can be arbitrarily adjusted according to the downstream application of the syngas.

[0017] The composite catalyst prepared in this invention was used to produce syngas by carbon dioxide electrolysis. The composition ratio of the syngas was precisely controllable, and it exhibited high activity, selectivity and stability.

[0018] The present invention has the following beneficial effects:

[0019] (1) The carbon dioxide electrolysis to syngas composite catalyst and its preparation method provided by the present invention are simple in process, have wide sources of raw materials, low cost, simple operation, no need for complex equipment, good repeatability, and are suitable for large-scale preparation.

[0020] (2) A composite catalyst for syngas production by carbon dioxide electrolysis is prepared by grinding and mixing a CO-preferential catalytic unit (component I) and a hydrogen-preferential catalytic unit (component II) using a physical mixing method. The mass ratio of component I to component II can be adjusted according to the specific requirements of downstream syngas applications, which is very convenient. Furthermore, with this composite catalyst and preparation method, the performance of component I and component II can be optimized separately, thereby selecting the best components I and II to maximize the syngas yield, showing promising application prospects.

[0021] (3) Physically mixing the preferred component I and component II to obtain a composite catalyst for carbon dioxide electrolysis to syngas can also avoid the enhanced and potentially detrimental interaction between the two active sites of CO evolution and hydrogen evolution that exists in the preparation of traditional bifunctional catalysts containing two active sites, thereby obtaining high syngas yield and selectivity. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0023] Figure 1 Scanning electron microscope image of composite catalyst S1 prepared in Example 1 of this invention.

[0024] Figure 2 The images show the XRD patterns of component I, component II, composite catalyst S1 in Example 1 of the present invention, and co-supported catalyst D1 in Comparative Example 1. Detailed Implementation

[0025] The present invention will be described below with reference to specific embodiments. Those skilled in the art will understand that these are illustrative and do not limit the scope of the invention in any way.

[0026] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] Weigh 0.01g nickel chloride, 0.1g glucose, 0.5g dicyandiamide, and 0.5g ammonium chloride, grind them evenly, and place them in a high-temperature tube furnace. Under a N2 atmosphere of 40 mL / min, heat the mixture to 900℃ at a heating rate of 3℃ / min and hold for 2 hours. After cooling to room temperature, nitrogen-doped carbon-supported nickel particles (component I) are obtained. Weigh 0.007g ammonium molybdate, 0.1g glucose, 0.5g dicyandiamide, and 0.5g ammonium chloride, grind them evenly, and place them in a high-temperature tube furnace. Under a N2 atmosphere of 40 mL / min, heat the mixture to 900℃ at a heating rate of 3℃ / min and hold for 2 hours. After cooling to room temperature, nitrogen-doped carbon-supported molybdenum carbide particles (component II) are obtained. Physically mix component I and component II at a mass ratio of 6:1, and denote this mixture as S1.

[0030] Example 2

[0031] Weigh 0.012g nickel nitrate, 0.15g citric acid, 0.7g melamine, and 0.5g ammonium chloride, grind them evenly, and place them in a high-temperature tube furnace. Under Ar atmosphere protection at a heating rate of 30 mL / min, heat to 800℃ at a heating rate of 5℃ / min and hold for 2h. After cooling to room temperature, nitrogen-doped carbon-loaded nickel particles (component I) are obtained. Weigh 0.0035g sodium molybdate, 0.15g citric acid, 0.7g melamine, and 0.5g ammonium chloride, grind them evenly, and place them in a high-temperature tube furnace. Under Ar atmosphere protection at a heating rate of 30 mL / min, heat to 800℃ at a heating rate of 5℃ / min and hold for 2h. After cooling to room temperature, nitrogen-doped carbon-loaded molybdenum carbide particles (component II) are obtained. Physically mix component I and component II at a mass ratio of 8:1, and denote as S2.

[0032] Example 3

[0033] Weigh 0.015g ferric chloride, 0.2g carboxymethyl cellulose, 1.0g urea, and 0.5g ammonium bicarbonate, grind them evenly, and place them in a high-temperature tube furnace. Under Ar atmosphere protection at a heating rate of 5℃ / min, heat to 850℃ and hold for 2h. After cooling to room temperature, nitrogen-doped carbon-supported nickel particles (component I) are obtained. Weigh 0.007g sodium molybdate, 0.2g carboxymethyl cellulose, 1.0g urea, and 0.5g ammonium bicarbonate, grind them evenly, and place them in a high-temperature tube furnace. Under Ar atmosphere protection at a heating rate of 5℃ / min, heat to 850℃ and hold for 2h. After cooling to room temperature, nitrogen-doped carbon-supported molybdenum carbide particles (component II) are obtained. Physically mix component I and component II at a mass ratio of 7:1, and denote as S3.

[0034] Comparative Example 1

[0035] Weigh 0.01g nickel chloride, 0.007g ammonium molybdate, 0.2g glucose, 1.0g dicyandiamide and 1.0g ammonium chloride, grind them evenly, and place them in a high-temperature tube furnace. Under the protection of N2 atmosphere at 40 mL / min, heat to 900℃ at a heating rate of 3℃ / min and hold for 2h. After cooling to room temperature, a nitrogen-doped carbon co-supported nickel-molybdenum carbide catalyst is obtained, denoted as D1.

[0036] Example 4

[0037] Weigh 0.012g cobalt chloride, 0.12g glucose, 0.55g dicyandiamide, and 0.6g ammonium chloride, grind them evenly, and place them in a high-temperature tube furnace. Under a N2 atmosphere of 50 mL / min, heat the mixture to 950℃ at a heating rate of 3℃ / min and hold for 2 hours. After cooling to room temperature, nitrogen-doped carbon-supported nickel particles (component I) are obtained. Weigh 0.01g ammonium molybdate, 0.12g glucose, 0.55g dicyandiamide, and 0.6g ammonium chloride, grind them evenly, and place them in a high-temperature tube furnace. Under a N2 atmosphere of 50 mL / min, heat the mixture to 950℃ at a heating rate of 3℃ / min and hold for 2 hours. After cooling to room temperature, nitrogen-doped carbon-supported molybdenum carbide particles (component II) are obtained. Physically mix component I and component II at a mass ratio of 3:2, denoted as S4.

[0038] Example 5

[0039] Weigh 0.035g nickel nitrate, 0.3g carboxymethyl cellulose, 1.0g polyaniline, and 1.0g ammonium carbonate, grind them evenly, and place them in a high-temperature tube furnace. Under a N2 atmosphere of 70 mL / min, heat the mixture to 700℃ at a heating rate of 5℃ / min and hold for 3 hours. After cooling to room temperature, nitrogen-doped carbon-loaded nickel particles (component I) are obtained. Weigh 0.012g sodium molybdate, 0.3g carboxymethyl cellulose, 1.0g polyaniline, and 1.0g ammonium carbonate, grind them evenly, and place them in a high-temperature tube furnace. Under a N2 atmosphere of 70 mL / min, heat the mixture to 700℃ at a heating rate of 5℃ / min and hold for 3 hours. After cooling to room temperature, nitrogen-doped carbon-loaded molybdenum carbide particles (component II) are obtained. Physically mix the components I and II at a mass ratio of 2:1, and denote this mixture as S5.

[0040] Example 6

[0041] Weigh 0.015g nickel acetylacetone, 0.25g citric acid, 1.75g ​​dicyandiamide, and 2g ammonium chloride. Grind them evenly and place them in a high-temperature tube furnace. Under Ar atmosphere protection at a heating rate of 5℃ / min, heat to 950℃ and hold for 1h. After cooling to room temperature, nitrogen-doped carbon-supported nickel particles (component I) are obtained. Weigh 0.008g sodium molybdate, 0.25g citric acid, 1.75g ​​dicyandiamide, and 2g ammonium chloride. Grind them evenly and place them in a high-temperature tube furnace. Under Ar atmosphere protection at a heating rate of 5℃ / min, heat to 950℃ and hold for 1h. After cooling to room temperature, nitrogen-doped carbon-supported molybdenum carbide particles (component II) are obtained. Physically mix component I and component II at a mass ratio of 2.5:1, denoted as S6.

[0042] Comparative Example 2

[0043] Weigh 0.035g nickel nitrate, 0.012g sodium molybdate, 0.6g carboxymethyl cellulose, 2.0g polyaniline and 2.0g ammonium carbonate, grind them evenly, and place them in a high-temperature tube furnace. Under the protection of N2 atmosphere at 70 mL / min, heat to 700℃ at a heating rate of 5℃ / min and hold for 3h. After cooling to room temperature, a nitrogen-doped carbon co-supported nickel-molybdenum carbide catalyst is obtained, denoted as D2.

[0044] Example 7

[0045] Weigh 0.02g nickel chloride, 0.2g citric acid, 1.5g urea, and 1.5g ammonium bicarbonate, grind them evenly, and place them in a high-temperature tube furnace. Under Ar atmosphere protection at a heating rate of 30 mL / min, heat to 900℃ at a heating rate of 4℃ / min and hold for 3h. After cooling to room temperature, nitrogen-doped carbon-supported nickel particles (component I) are obtained. Weigh 0.015g ammonium molybdate, 0.2g citric acid, 1.5g urea, and 1.5g ammonium bicarbonate, grind them evenly, and place them in a high-temperature tube furnace. Under Ar atmosphere protection at a heating rate of 30 mL / min, heat to 900℃ at a heating rate of 4℃ / min and hold for 3h. After cooling to room temperature, nitrogen-doped carbon-supported molybdenum carbide particles (component II) are obtained. Physically mix component I and component II at a mass ratio of 0.5:1, and denote this mixture as S7.

[0046] Example 8

[0047] Weigh 0.03g of nickel acetylacetone, 0.6g of glucose, 3g of melamine, and 3g of ammonium chloride. Grind them evenly and place them in a high-temperature tube furnace. Under a N2 atmosphere of 10 mL / min, heat the furnace to 850℃ at a heating rate of 5℃ / min and hold for 1 hour. After cooling to room temperature, nitrogen-doped carbon-supported nickel particles (component I) are obtained. Weigh 0.02g of sodium molybdate, 0.6g of glucose, 3g of melamine, and 3g of ammonium chloride. Grind them evenly and place them in a high-temperature tube furnace. Under a N2 atmosphere of 10 mL / min, heat the furnace to 850℃ at a heating rate of 5℃ / min and hold for 1 hour. After cooling to room temperature, nitrogen-doped carbon-supported molybdenum carbide particles (component II) are obtained. Physically mix component I and component II at a mass ratio of 1:1, denoted as S8.

[0048] Example 9

[0049] Weigh 0.045 g nickel nitrate, 0.42 g glucose, 1.7 g urea and 2.0 g ammonium carbonate, grind them evenly, and place them in a high-temperature tube furnace. Under Ar atmosphere protection at a heating rate of 4 °C / min, heat to 750 °C and hold for 2 h. After cooling to room temperature, nitrogen-doped carbon-supported nickel particles (component I) are obtained. Weigh 0.02 g sodium molybdate, 0.42 g glucose, 1.7 g urea and 2.0 g ammonium carbonate, grind them evenly, and place them in a high-temperature tube furnace. Under Ar atmosphere protection at a heating rate of 4 °C / min, heat to 750 °C and hold for 2 h. After cooling to room temperature, nitrogen-doped carbon-supported molybdenum carbide particles (component II) are obtained. Physically mix component I and component II at a mass ratio of 1.2:1, denoted as S9.

[0050] Comparative Example 3

[0051] Weigh 0.045 g nickel nitrate, 0.02 g sodium molybdate, 0.84 g glucose, 3.4 g urea and 4.0 g ammonium carbonate, grind them evenly, and place them in a high-temperature tube furnace. Under Ar atmosphere protection at a heating rate of 40 mL / min, heat the furnace to 750 °C and hold for 2 h. After cooling to room temperature, a nitrogen-doped carbon co-supported nickel-molybdenum carbide catalyst is obtained, denoted as D3.

[0052] Table 1. Performance of the catalysts prepared in the above examples in electrocatalytic reduction of carbon dioxide to syngas (applied potential -0.85V vs RHE).

[0053]

Claims

1. A method for preparing a composite catalyst for precisely controllable proportioning of syngas produced by carbon dioxide electrolysis, characterized in that, The preparation includes the following steps: Step 1: Grind and mix iron-based metal salts, carbon source, nitrogen source and pore-forming agent to obtain solid powder A. Calcine solid powder A in an inert atmosphere to obtain component I. Step 2: Grind and mix molybdenum salt, carbon source, nitrogen source and pore-forming agent, or grind and mix tungsten salt, carbon source, nitrogen source and pore-forming agent to obtain solid powder B. Calcine solid powder B in an inert atmosphere to obtain component II. Step 3: Physically mix component I prepared in step 1 and component II prepared in step 1 to obtain the composite catalyst.

2. The method for preparing a composite catalyst for precisely controllable proportioning of syngas produced by carbon dioxide electrolysis according to claim 1, characterized in that, The mass ratio of the iron-based metal salt, carbon source, nitrogen source and pore-forming agent in step 1 is 1:4-500:5-300:5-300. The mass ratio of the molybdenum salt or tungsten salt, carbon source, nitrogen source and pore-forming agent in step 1 is 1:2-500:5-300:2-300.

3. The method for preparing a composite catalyst for precisely controllable proportioning of syngas produced by carbon dioxide electrolysis according to claim 1, characterized in that, The inert atmosphere described in steps 1 and 2 is nitrogen or argon, with a flow rate of 5–250 ml / min, a calcination temperature of 300–1000 °C, and a calcination time of 30–300 min.

4. The method for preparing a composite catalyst for precisely controllable proportioning of syngas produced by carbon dioxide electrolysis according to claim 1, characterized in that, The iron-based metal salt mentioned in step 1 is selected from ferric acetylacetone, ferric nitrate, ferric acetate, ferric chloride, ferric sulfate, cobalt nitrate, cobalt acetylacetone, cobalt acetate, cobalt chloride, cobalt sulfate, nickel nitrate, nickel acetate, nickel chloride, nickel sulfate, and nickel acetylacetone; the molybdenum salt or tungsten salt mentioned in step 2 is selected from ammonium molybdate, sodium molybdate, ammonium tungstate, and sodium tungstate; the carbon source mentioned in steps 1 and 2 is selected from glucose, citric acid, and carboxymethyl cellulose; the nitrogen source is selected from melamine, urea, dicyandiamide, and polyaniline; and the pore-forming agent is selected from ammonium carbonate, ammonium bicarbonate, ammonium chloride, and ammonium nitrate.

5. The method for preparing a composite catalyst for precisely controllable proportioning of syngas produced by carbon dioxide electrolysis according to claim 1, characterized in that, In step 3, the mass ratio of component I to component II can be adjusted arbitrarily according to the downstream application of the syngas.

6. A composite catalyst for the precise and controllable production of syngas by carbon dioxide electrolysis, characterized in that, The composite catalyst is prepared by any one of the preparation methods described in claims 1-5.

7. A composite catalyst prepared by any one of claims 1-5, characterized in that, Used for the electrolysis of carbon dioxide to produce syngas.

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