Copper-cerium composite material and preparation method thereof, electrocatalyst and application thereof

Abstract

The application relates to a copper-cerium composite material and a preparation method thereof, an electrocatalyst and application thereof. The preparation method of the copper-cerium composite material comprises the following steps: mixing a copper salt, a reducing agent and a first solvent to perform a reduction reaction to prepare a copper oxide material; the reducing agent comprises ethanolamine; and the copper oxide material and a cerium salt are mixed and subjected to calcination treatment to prepare the copper-cerium composite material. The preparation method can prepare a copper-cerium composite material with a specific morphology. The copper-cerium composite material with the specific morphology is used for catalyzing electrochemical carbon dioxide reduction, and the copper-cerium composite material has relatively high Faraday efficiency and current density on carbon two plus products, especially on ethanol, and has relatively good stability, and has relatively good selectivity and activity on carbon two plus products, especially on ethanol, in electrochemical carbon dioxide reduction in an acid medium.

Description

Technical Field

[0001] This application relates to the field of electrocatalysis technology, and in particular to a copper-cerium composite material and its preparation method, an electrocatalyst and its application. Background Technology

[0002] In recent years, the excessive combustion of fossil fuels has caused atmospheric CO2 concentrations to exceed 400 ppm. Utilizing renewable electricity to reduce CO2 to chemical fuels is a highly effective and sustainable technological approach. Based on different catalysts and reaction pathways, the electrochemical carbon dioxide reduction reaction (CO2RR) can yield more than 16 different high-value-added products, such as CH4, CO, formic acid, ethylene, and ethanol. This provides a potential solution to address the carbon balance problem and achieve carbon neutrality, while creating an economically viable carbon cycle in a sustainable manner.

[0003] Catalytic materials used for CO2RR mainly include metals and their alloys, metal oxides / sulfides, and carbon materials. Among them, copper, gold, tin, and other metal materials have been extensively studied as electrocatalysts for CO2 reduction. It is generally believed that the activity and selectivity of catalytic materials are determined by the adsorption-desorption behavior of reaction intermediates (or products) at active sites. Based on the adsorption-desorption capabilities of various intermediates on different metals, pure metal catalysts are generally considered to be divided into three categories: those with Sn, Hg, Pb, In, Bi, etc., tend to adsorb carbon dioxide molecules with oxygen as the binding site, with formic acid as the main product; those with Au, Ag, Zn, and Pd, etc., can bind sufficiently tightly with *COOH, with CO as the main product; copper is currently the main metal catalyst found to produce high-carbon products. CO adsorbed on the surface of copper catalysts is not easily desorbed and can undergo coupling reactions with adjacent *CO to obtain high-carbon products. However, due to the competition and complex reaction pathway of the hydrogen evolution reaction (HER) in CO2RR, the selectivity of traditional catalytic materials for CO2RR in acidic media is not ideal, especially for high-energy-density products such as ethanol, the performance is very limited.

[0004] Therefore, it is necessary to improve traditional technologies. Summary of the Invention

[0005] Based on this, this application provides a copper-cerium composite material with high selectivity and activity for ethanol, its preparation method, an electrocatalyst, and its application.

[0006] The technical solution to the above-mentioned technical problems in this application is as follows.

[0007] The first aspect of this application provides a method for preparing a copper-cerium composite material, comprising the following steps:

[0008] A copper oxide material is prepared by mixing a copper salt, a reducing agent, and a first solvent and then carrying out a reduction reaction; the reducing agent includes ethanolamine.

[0009] The copper oxide material and cerium salt are mixed and calcined to prepare a copper-cerium composite material.

[0010] In some embodiments, the reduction reaction temperature in the preparation method of the copper-cerium composite material is 20°C to 180°C.

[0011] In some embodiments, in the preparation method of the copper-cerium composite material, the mass ratio of the cerium salt to the copper oxide material is (0.2~0.8):1.

[0012] In some embodiments, the method for preparing the copper-cerium composite material satisfies at least one of the following characteristics:

[0013] (1) The copper salt includes at least one of copper nitrate, copper chloride and copper sulfate;

[0014] (2) The cerium salt includes at least one of cerium nitrate, cerium chloride, and cerium sulfate;

[0015] (3) The first solvent includes water;

[0016] (4) The volume ratio of the reducing agent to the mass ratio of the copper salt is (0.2~0.8) μL / mg;

[0017] (5) The calcination treatment is carried out at a temperature of 300℃~500℃ for a time of 0.5 h~5 h.

[0018] In some embodiments, the step of mixing copper oxide material and cerium salt and then calcining them in the preparation method of copper-cerium composite material includes:

[0019] The copper oxide material, the cerium salt, and the second solvent are mixed and ultrasonicated, then dried to obtain the copper-cerium mixed material.

[0020] The copper-cerium mixture is subjected to calcination treatment.

[0021] In some embodiments, in the method for preparing the copper-cerium composite material, the second solvent includes at least one of ethanol and water.

[0022] The second aspect of this application provides a copper-cerium composite material, which is prepared using the preparation method provided in the first aspect of this application.

[0023] In some embodiments, the copper-cerium composite material satisfies at least one of the following characteristics:

[0024] (1) In the copper-cerium composite material, the amount of cerium atoms accounts for 5% to 20% of the total amount of cerium atoms and copper atoms;

[0025] (2) The copper-cerium composite material has a leaf-like or petal-like morphology.

[0026] A third aspect of this application provides an electrocatalyst, including the copper-cerium composite material provided in the second aspect of this application.

[0027] The fourth aspect of this application provides the application of the electrocatalyst provided in the third aspect of this application as a catalyst in the electrochemical reduction of carbon dioxide.

[0028] The fifth aspect of this application provides an electrochemical reactor, including a membrane layer and an electrocatalyst provided in the third aspect of this application, wherein the electrocatalyst is disposed on the membrane layer.

[0029] Compared with existing technologies, the preparation method of copper-cerium composite material of this application has the following advantages:

[0030] The above-mentioned method for preparing copper-cerium composite materials involves reducing copper salts under the action of a specific reducing agent, resulting in copper oxide materials with a leaf-like or petal-like morphology. Using this copper oxide material with a specific morphology as a template, it is mixed with cerium salts and calcined to obtain a copper-cerium composite material with the corresponding leaf-like or petal-like morphology. When this copper-cerium composite material with a specific morphology is used for catalytic electrochemical carbon dioxide reduction, it exhibits high Faradaic efficiency and current density for C2 addition products, especially for ethanol, and also demonstrates good stability.

[0031] The copper-cerium composite material prepared by the above method exhibits good selectivity and activity towards C2 addition products in acidic medium electrochemical carbon dioxide reduction, especially towards ethanol. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 The image shows a TEM image of the copper-cerium composite material prepared in Example 1.

[0034] Figure 2 The TEM mapping elemental analysis diagram of the copper-cerium composite material prepared in Example 1 is shown below.

[0035] Figure 3 Here is a SEM image of the copper-cerium composite material prepared in Example 1;

[0036] Figure 4 The image shows the elemental analysis of the copper-cerium composite material prepared in Example 1 via SEM mapping.

[0037] Figure 5 The XRD pattern of the copper-cerium composite material prepared in Example 1 is shown below.

[0038] Figure 6 Raman spectroscopy for the copper-cerium composite material prepared in Example 1;

[0039] Figure 7 The image shows a TEM image of the copper-cerium composite material prepared in Example 4.

[0040] Figure 8 TEM image of CuO nanosheets prepared in Comparative Example 1;

[0041] Figure 9 XPS spectra of copper in the copper-cerium composite material prepared in Example 1 and the CuO nanosheets prepared in Comparative Example 1.

[0042] Figure 10 XPS spectra of cerium in the copper-cerium composite material prepared in Example 1 and the CuO nanosheets prepared in Comparative Example 1.

[0043] Figure 11 The product distribution diagram of the electrocatalytic carbon dioxide reduction of the copper-cerium composite material prepared in Example 1 under different voltages is shown.

[0044] Figure 12 The product distribution diagram of the electrocatalytic carbon dioxide reduction of the copper-cerium composite material prepared in Example 2 under different voltages is shown.

[0045] Figure 13 The product distribution diagram of the electrocatalytic carbon dioxide reduction of the copper-cerium composite material prepared in Example 3 under different voltages;

[0046] Figure 14 This is a product distribution diagram of the electrocatalytic carbon dioxide reduction of the copper-cerium composite material prepared in Example 4 under different voltages;

[0047] Figure 15 The product distribution diagram of the electrocatalytic reduction of carbon dioxide by CuO nanosheets prepared in Comparative Example 1 under different voltages is shown.

[0048] Figure 16 The product distribution diagram of the electrocatalytic carbon dioxide reduction of the copper-cerium composite material prepared in Comparative Example 2 under different voltages is shown.

[0049] Figure 17The constant pressure curve and Faraday efficiency of the copper-cerium composite material prepared in Example 1 in the electrocatalytic carbon dioxide reduction reaction in acidic medium are shown.

[0050] Figure 18 This is a graph showing the transmembrane ratio of liquid products detected in the anolyte of the copper-cerium composite material prepared in Example 1 in an acidic medium. Detailed Implementation

[0051] Reference will now be made to detailed embodiments of the present invention, one or more of which are described below. Each example is provided for explanation and not for limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to the invention without departing from its scope or spirit. For example, features described or illustrated as part of one embodiment may be used in another embodiment to produce further embodiments.

[0052] Therefore, this invention is intended to cover such modifications and variations falling within the scope of the appended claims and their equivalents. Other objects, features, and aspects of the invention are disclosed in or will be apparent from the following detailed description. It will be understood by those skilled in the art that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of the invention.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0054] The terms “comprising,” “including,” or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element preceded by the phrase “comprising one…” does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. The indefinite articles “a” and “an” preceding an element or component of the invention are not restrictive in terms of the number of elements or components (i.e., the number of times they appear). Therefore, “an” or “an” should be interpreted as including one or at least one, and singular elements or components also include plural forms, unless the quantity clearly refers only to the singular. “A plurality” means at least two, such as two, three, etc., unless otherwise expressly specified.

[0055] The weights of the relevant components mentioned in the embodiments of this invention can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this invention is within the scope disclosed in the embodiments of this invention. Specifically, the weights mentioned in the embodiments of this invention can be well-known units of mass in the chemical industry, such as μg, mg, g, and kg.

[0056] Unless otherwise shown or indicated in the operational embodiments, all figures used to represent the amounts, physicochemical properties, etc., of ingredients in the specification and claims are to be understood to be adjusted by the term "about" in all cases. For example, therefore, unless stated to the contrary, the numerical parameters listed in the foregoing specification and appended claims are approximations, and those skilled in the art can appropriately modify these approximations to obtain the desired characteristics by utilizing the teachings disclosed herein. The use of numerical ranges indicated by endpoints includes all numbers within that range and any range within that range; for example, 1 to 5 includes 1, 1.1, 1.3, 1.5, 2, 2.75, 3, 3.80, 4, and 5, etc.

[0057] Traditional methods for preparing copper-cerium composites include one-step pyrolysis and liquid-phase synthesis. One-step pyrolysis directly pyrolyzes two metal precursors in a single step. However, the resulting copper-cerium composites exhibit inhomogeneous morphology and poor selectivity and activity towards the C2 addition product during electrochemical carbon dioxide reduction in acidic media. Liquid-phase synthesis methods, including one-pot and electrodisplacement methods, face challenges such as varying synthesis temperatures for the two oxides, incompatibility of synthesis methods, and solvent limitations restricting preparation to low temperatures. Consequently, the prepared copper-cerium composites show poor overall performance during electrochemical carbon dioxide reduction in acidic media.

[0058] One embodiment of this application provides a method for preparing a copper-cerium composite material, comprising the following steps:

[0059] Step S10: The copper salt, reducing agent and first solvent are mixed and then subjected to a reduction reaction to prepare copper oxide material; the reducing agent includes ethanolamine.

[0060] In some of these examples, the temperature of the reduction reaction in step S10 is 20°C to 180°C.

[0061] It is understood that the temperature of the reduction reaction includes, but is not limited to, 20℃, 22℃, 25℃, 28℃, 30℃, 32℃, 35℃, 38℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, and 180℃; in some examples, any two of these point values ​​can be used as the endpoints within a range, and the same applies below.

[0062] In some of these examples, the temperature of the reduction reaction in step S10 is 20°C to 50°C.

[0063] In some of these examples, the temperature of the reduction reaction in step S10 is 20°C to 40°C.

[0064] In some of these examples, the temperature of the reduction reaction in step S10 is 20°C to 30°C.

[0065] By controlling the temperature of the reduction reaction and using a specific reducing agent, the morphology of copper oxide materials can be effectively controlled. Furthermore, by controlling the temperature of the reduction reaction in a higher range and using a specific reducing agent, the morphology of copper oxide materials can be controlled to be petal-like. By controlling the temperature of the reduction reaction in a lower range (20℃~50℃) and using a specific reducing agent, the morphology of copper oxide materials can be effectively controlled to be leaf-like.

[0066] In some of these examples, the reduction reaction takes 6 h to 24 h in step S10.

[0067] It is understood that the reduction reaction time includes, but is not limited to, 6 h, 8 h, 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, and 24 h.

[0068] In some of these examples, the reduction reaction takes 10 to 15 hours in step S10.

[0069] It is understood that copper salts include, but are not limited to, copper nitrates, copper chlorides, and copper sulfates.

[0070] In some of these examples, in step S10, the copper salt includes at least one of copper nitrate, copper chloride, and copper sulfate.

[0071] Optionally, the copper salt includes copper nitrate.

[0072] In some of these examples, in step S10, the first solvent comprises water.

[0073] In some of these examples, in step S10, the volume ratio of the reducing agent to the mass ratio of the copper salt is (0.2~0.8) μL / mg.

[0074] It is understood that the volume ratio of the reducing agent to the mass of the copper salt includes, but is not limited to, 0.2 μL / mg, 0.3 μL / mg, 0.4 μL / mg, 0.5 μL / mg, 0.6 μL / mg, 0.7 μL / mg, and 0.8 μL / mg.

[0075] In some of these examples, in step S10, the volume ratio of the reducing agent to the mass ratio of the copper salt is (0.3~0.6) μL / mg.

[0076] In some of these examples, step S10 includes:

[0077] The copper salt and a portion of the first solvent are mixed to obtain a copper salt solution;

[0078] The reducing agent and the remaining first solvent are mixed to obtain a reducing agent solution;

[0079] The reduction reaction is carried out by mixing the copper salt solution and the reducing agent solution.

[0080] In some examples, step S10, after the reduction reaction is complete, also includes:

[0081] The reaction solution after the reduction reaction was subjected to solid-liquid separation, and the solid phase was washed to obtain copper oxide material.

[0082] It is understood that this application does not limit the method of solid-liquid separation, including but not limited to centrifugation and filtration.

[0083] In some of these examples, in step S10, the solid-liquid separation is performed by centrifugation.

[0084] Furthermore, the centrifugation speed is 6000 r / min to 10000 r / min.

[0085] It is understood that centrifugation speeds include, but are not limited to, 6000 r / min, 7000 r / min, 8000 r / min, 9000 r / min, and 10000 r / min.

[0086] In some of these examples, in step S10, the washing solvent includes at least one of water and ethanol.

[0087] In some of these examples, in step S10, the washing solvent includes water and ethanol.

[0088] Furthermore, the volume ratio of water to ethanol is (1~5):1.

[0089] Optionally, the volume ratio of water to ethanol is 1:1.

[0090] Step S20: Mix copper oxide material and cerium salt and calcine them to prepare copper-cerium composite material.

[0091] The above-mentioned method for preparing copper-cerium composite materials involves reducing copper salts under the action of a specific reducing agent, resulting in copper oxide materials with a leaf-like or petal-like morphology. Using this copper oxide material with a specific morphology as a template, it is mixed with cerium salts and calcined to obtain a copper-cerium composite material with the corresponding leaf-like or petal-like morphology. When this copper-cerium composite material with a specific morphology is used for catalytic electrochemical carbon dioxide reduction, it exhibits high Faradaic efficiency and current density for C2 addition products, especially for ethanol, and also demonstrates good stability.

[0092] The copper-cerium composite material prepared by the above method exhibits good selectivity and activity towards C2 addition products in acidic medium electrochemical carbon dioxide reduction, especially towards ethanol.

[0093] It is understandable that the morphology of copper-cerium composite materials prepared using petal-shaped copper oxide materials as templates is also petal-shaped, and the morphology of copper-cerium composite materials prepared using leaf-shaped copper oxide materials as templates is also leaf-shaped. Among them, the leaf-shaped copper-cerium composite material has better selectivity and activity for C2 addition products in acidic medium electrochemical carbon dioxide reduction, which is better than that of the petal-shaped copper-cerium composite material in acidic medium electrochemical carbon dioxide reduction.

[0094] In some of these examples, in step S20, the mass ratio of cerium salt to copper oxide material is (0.2~0.8):1.

[0095] It is understood that the mass ratio of cerium salt to copper oxide material includes, but is not limited to, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, and 0.8:1.

[0096] In some examples, in step S20, the mass ratio of cerium salt to copper oxide material is (0.25~0.6):1.

[0097] In some examples, in step S20, the mass ratio of cerium salt to copper oxide material is (0.4~0.6):1.

[0098] By controlling the mass ratio of cerium salt to copper oxide, the percentage of cerium atoms in the final copper-cerium composite material can be controlled.

[0099] It is understood that cerium salts include, but are not limited to, cerium nitrates, cerium chlorides, and cerium sulfates.

[0100] In some of these examples, in step S20, the cerium salt includes at least one of cerium nitrate, cerium chloride, and cerium sulfate.

[0101] Optionally, in step S20, the cerium salt includes cerium nitrate.

[0102] In some of these examples, in step S20, the calcination temperature is 300℃~500℃ and the time is 0.5 h~5 h.

[0103] It is understood that the calcination temperature includes, but is not limited to, 300℃, 320℃, 350℃, 380℃, 400℃, 420℃, 450℃, 480℃, and 500℃, and the time includes, but is not limited to, 0.5 h, 0.8 h, 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h, 2.2 h, 2.5 h, 2.8 h, 3 h, 3.2 h, 3.5 h, 3.8 h, 4 h, 4.2 h, 4.5 h, 4.8 h, and 5 h.

[0104] In some of these examples, the calcination temperature in step S20 is 350°C to 450°C.

[0105] In some of these examples, the calcination time in step S20 is 0.5 h to 2 h.

[0106] In some of these examples, step S20 includes:

[0107] The copper oxide material, cerium salt, and a second solvent were mixed and ultrasonicated, then dried to obtain a copper-cerium mixed material.

[0108] The copper-cerium mixture was calcined.

[0109] In some of these examples, in step S20, the second solvent includes at least one of ethanol and water.

[0110] In some of these examples, in step S20, the second solvent comprises ethanol and water.

[0111] Furthermore, the volume ratio of ethanol to water is (8~15):1.

[0112] It is understood that the volume ratio of ethanol to water includes, but is not limited to, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, and 15:1.

[0113] In some of these examples, the ultrasound duration in step S20 is 1 h to 5 h.

[0114] It is understood that the ultrasound duration includes, but is not limited to, 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h, 2.2 h, 2.5 h, 2.8 h, 3 h, 3.2 h, 3.5 h, 3.8 h, 4 h, 4.2 h, 4.5 h, 4.8 h, and 5 h.

[0115] In some examples, step S20, after the calcination process is completed, also includes:

[0116] The calcined product was centrifuged and washed sequentially to obtain a copper-cerium composite material.

[0117] Furthermore, the centrifugation speed is 6000 r / min to 10000 r / min.

[0118] It is understood that centrifugation speeds include, but are not limited to, 6000 r / min, 7000 r / min, 8000 r / min, 9000 r / min, and 10000 r / min.

[0119] In some of these examples, in step S20, the washing solvent includes at least one of water and ethanol.

[0120] In some of these examples, in step S20, the washing solvent includes water and ethanol.

[0121] Furthermore, the volume ratio of water to ethanol is (1~5):1.

[0122] Optionally, the volume ratio of water to ethanol is 1:1.

[0123] One embodiment of this application provides a copper-cerium composite material, which is prepared using the above-described preparation method.

[0124] The copper-cerium composite material prepared by the above method exhibits good selectivity and activity towards C2 addition products in electrochemical carbon dioxide reduction, especially in acidic medium electrochemical carbon dioxide reduction.

[0125] In some of these examples, the amount of cerium atoms in the copper-cerium composite material accounts for 5% to 20% of the total amount of cerium and copper atoms.

[0126] It is understood that the percentage of cerium atoms in the total amount of cerium and copper atoms includes, but is not limited to, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, and 20%.

[0127] In some of these examples, the amount of cerium atoms in the copper-cerium composite material accounts for 5% to 14% of the total amount of cerium and copper atoms.

[0128] In some of these examples, the amount of cerium atoms in the copper-cerium composite material accounts for 7% to 10% of the total amount of cerium and copper atoms.

[0129] In some of these examples, the copper-cerium composite material exhibits a leaf-like or petal-like morphology.

[0130] Preferably, the copper-cerium composite material has a leaf-like morphology.

[0131] The leaf-shaped copper-cerium composite material exhibits superior selectivity and activity for C2 addition products in acidic medium electrochemical carbon dioxide reduction, compared to the petal-shaped copper-cerium composite material.

[0132] One embodiment of this application provides the application of the above-described copper-cerium composite material in the preparation of an electrocatalyst. Another embodiment of this application provides an electrocatalyst comprising the above-described copper-cerium composite material.

[0133] The electrocatalyst of this application includes the copper-cerium composite material provided in this application, and therefore has at least the same advantages as the copper-cerium composite material described above.

[0134] One embodiment of this application provides the application of the above-described electrocatalyst as a catalyst in electrochemical carbon dioxide reduction.

[0135] In some examples, the electrochemical carbon dioxide reduction includes the following steps: using a titanium mesh loaded with iridium oxide as the anode, carbon paper loaded with the above-mentioned catalyst as the working electrode, a sulfuric acid solution containing potassium chloride as the cathode electrolyte, a sulfuric acid solution as the anolyte, and an Ag / AgCl electrode as the reference electrode, the mobile phase electrochemical reduction reaction is carried out under the condition of carbon dioxide introduction.

[0136] In some examples, the electrochemical carbon dioxide reduction includes the following steps: using a titanium mesh loaded with iridium oxide as the anode, commercial 30T carbon paper loaded with a catalyst as the working electrode, a sulfuric acid solution containing 3 M KCl as the cathode electrolyte, 0.5 M H2SO4 as the anolyte, and an Ag / AgCl electrode as the reference electrode, the mobile phase electrochemical reduction reaction is carried out under the condition of carbon dioxide introduction.

[0137] It is understood that the catalyst is the electrocatalyst of this application provided above or the electrocatalyst obtained by the preparation method provided above.

[0138] In some of these examples, the carbon paper for the working electrode is commercial 30T carbon paper.

[0139] In some of these examples, the catalyst loading was 1.00 mg / cm³. 2 ~2.00 mg / cm 2 .

[0140] In some of these examples, the concentration of sulfuric acid solution in the cathode electrolyte is 0.5 mmol / L to 50 mmol / L.

[0141] In some of these examples, the concentration of potassium chloride in the cathode electrolyte is 2 mol / L to 4 mol / L.

[0142] Optionally, the concentration of potassium chloride in the cathode electrolyte is 3 mol / L.

[0143] In some of these examples, the concentration of sulfuric acid solution in the anolyte ranges from 0.5 mmol / L to 50 mmol / L.

[0144] In some of these examples, the carbon dioxide flow rate is preferably 50 sccm to 30 sccm.

[0145] In some of these examples, the parameters for the reduction reaction include: a temperature of 20°C to 35°C; a pressure of one standard atmosphere (1 atm); and a reduction potential range preferably from -1.0 V to -1.6 V. RHE .

[0146] One embodiment of this application provides an electrochemical reactor, including a membrane layer and the aforementioned electrocatalyst, wherein the electrocatalyst is disposed on the membrane layer.

[0147] In some of these examples, the membrane in the electrochemical reactor is selected from ion exchange membranes or gas diaphragms.

[0148] Furthermore, the ion exchange membrane can be a cation exchange membrane or anion exchange membrane.

[0149] In some of these examples, the reactants in the electrochemical reactor include carbon dioxide.

[0150] The electrochemical reactor of this application includes the electrocatalyst provided in this application, and therefore has at least the same advantages as the electrocatalyst described above.

[0151] The present application will be described in further detail below with reference to specific embodiments, but the embodiments of the present application are not limited thereto.

[0152] Example 1

[0153] Step 1: Preparation of leaf-shaped CuO nanosheets

[0154] 438.2 mg of copper nitrate was added to a 1000 mL beaker containing 500 mL of water and stirred for 5 min to obtain a copper salt solution. 500 mL of water was measured into a volumetric flask, and 98 μL of ethanolamine was added dropwise twice. The mixture was stirred for 5 min to obtain a reducing agent solution. The reducing agent solution was poured into the copper salt solution, stirred, and the reduction reaction was carried out at 25 °C for 12 h in a drying oven. After naturally cooling to room temperature, the product was collected by centrifugation at 8000 r / min and washed twice with water and ethanol (water to ethanol volume ratio 1:1) to obtain leaf-shaped CuO nanosheets.

[0155] Step 2: Using leaf-shaped CuO nanosheets as templates, prepare leaf-shaped CuO / CeO2 nanosheet composite materials.

[0156] Take 20 mg of the leaf-shaped CuO nanosheets obtained in the first step, add 10.9 mg of cerium nitrate hexahydrate, 2 mL of ethanol and 0.2 mL of water, sonicate in an ultrasonic machine for 2 h, then dry the solvent in a vacuum drying oven, scrape it off and place it in a magnetic boat, heat it in a muffle furnace to 400℃ for 18 min and hold for 1 h, then immediately take it out and let it cool naturally to room temperature, collect the product by centrifugation at 8000 r / min, wash it twice with water and ethanol (water and ethanol volume ratio of 1:1) to obtain copper-cerium composite material. ICP test showed that in the copper-cerium composite material prepared in Example 1, the amount of cerium atoms accounted for 8.9% of the total amount of cerium atoms and copper atoms.

[0157] TEM image of the copper-cerium composite material prepared in Example 1 is shown below. Figure 1 As shown, the copper-cerium composite material has a leaf-like morphology and consists of relatively thin two-dimensional nanosheets. It is relatively uniform overall, with a lateral dimension of approximately 380 nm.

[0158] TEM mapping elemental analysis was performed on the copper-cerium composite material prepared in Example 1, such as... Figure 2 As shown, elemental analysis reveals that Ce, Cu, and O are uniformly distributed in the copper-cerium composite material.

[0159] SEM images of the copper-cerium composite material prepared in Example 1 are shown below. Figure 3 As shown, the results indicate that the copper-cerium composite material prepared in Example 1 is entirely leaf-shaped, with uniform morphology and similar size.

[0160] SEM elemental analysis was performed on the copper-cerium composite material prepared in Example 1, such as... Figure 4 As shown, EDS mapping indicates that the copper-cerium composite material prepared in Example 1 is composed of three elements: Ce, Cu, and O.

[0161] The copper-cerium composite material prepared in Example 1 was subjected to XRD testing, as shown below. Figure 5As shown, the horizontal axis 2Theta (degree) refers to 2θ (degree), and the vertical axis Intensity represents the intensity. Figure 5 The results show that the copper-cerium composite material prepared in Example 1 has the main diffraction peaks of the copper oxide monoclinic phase and the main diffraction peaks of the cerium oxide cubic phase, suggesting that the copper-cerium composite material is a nano-heterojunction composite material.

[0162] Raman spectroscopy analysis was performed on the copper-cerium composite material prepared in Example 1, as follows: Figure 6 As shown, the horizontal axis Raman shift refers to the Raman displacement, and the vertical axis Intensity refers to the Raman intensity. Figure 6 The results show that the copper-cerium composite material prepared in Example 1 has a diameter of 288 cm. -1 336 cm -1 624 cm -1 The vibrational peak of copper oxide is present, along with that of cerium oxide at 457 cm⁻¹. -1 The F2g vibrational mode peak indicates that CuO / CeO2 nanosheet composite material was successfully prepared.

[0163] Example 2

[0164] The second step of Example 2 is basically the same as that of Example 1, except that the mass of cerium nitrate hexahydrate added in the second step is 5 mg. The second step of Example 2 is as follows:

[0165] Step 2: Using leaf-shaped CuO nanosheets as templates, prepare leaf-shaped CuO / CeO2 nanosheet composite materials.

[0166] 20 mg of the leaf-shaped CuO nanosheets obtained in the first step were added to 5 mg of cerium nitrate hexahydrate, 2 mL of ethanol, and 0.2 mL of water. The mixture was sonicated for 2 h, and then the solvent was dried in a vacuum drying oven. The nanosheets were scraped off and placed in a magnetic boat, heated to 400 °C in a muffle furnace for 18 min and held for 1 h. The mixture was then immediately removed and allowed to cool naturally to room temperature. The product was collected by centrifugation at 8000 r / min and washed twice with water and ethanol (water to ethanol volume ratio of 1:1) to obtain the leaf-shaped CuO / CeO2 nanosheet composite material. ICP testing showed that the amount of cerium atoms in the copper-cerium composite material prepared in Example 2 accounted for 5.8% of the total amount of cerium and copper atoms.

[0167] Example 3

[0168] The second step of Example 3 is basically the same as that of Example 1, except that the mass of cerium nitrate hexahydrate added in the second step is 15.5 mg. The second step of Example 3 is as follows:

[0169] Step 2: Using leaf-shaped CuO nanosheets as templates, prepare leaf-shaped CuO / CeO2 nanosheet composite materials.

[0170] 20 mg of the leaf-shaped CuO nanosheets obtained in the first step were added to 15.5 mg of cerium nitrate hexahydrate, 2 mL of ethanol, and 0.2 mL of water. The mixture was sonicated for 2 h, and then the solvent was dried in a vacuum drying oven. The nanosheets were scraped off and placed in a magnetic boat, heated to 400 °C in a muffle furnace for 18 min and held for 1 h. The mixture was then immediately removed and allowed to cool naturally to room temperature. The product was collected by centrifugation at 8000 r / min and washed twice with water and ethanol (water to ethanol volume ratio of 1:1) to obtain the leaf-shaped CuO / CeO2 nanosheet composite material. ICP testing showed that the amount of cerium atoms in the copper-cerium composite material prepared in Example 3 accounted for 15.2% of the total amount of cerium and copper atoms.

[0171] Example 4

[0172] The process is basically the same as in Example 1, except that in the first step of Example 4, the temperature of the reduction reaction is 180°C. The first step of Example 4 is as follows:

[0173] Step 1: Preparation of petal-shaped CuO nanosheets

[0174] 438.2 mg of copper nitrate was added to a 1000 mL beaker containing 500 mL of water and stirred for 5 min to obtain a copper salt solution. 500 mL of water was measured into a volumetric flask, and 98 μL of ethanolamine was added dropwise twice. The mixture was stirred for 5 min to obtain a reducing agent solution. The reducing agent solution was poured into the copper salt solution and stirred. One-twentieth of the total volume was added to the inner liner of the reaction vessel, and the reduction reaction was carried out at 180 °C for 12 h in a drying oven. After naturally cooling to room temperature, the product was collected by centrifugation at 8000 r / min and washed twice with water and ethanol (water to ethanol volume ratio 1:1) to obtain petal-shaped CuO nanosheets.

[0175] Step 2: Using petal-shaped CuO nanosheets as templates, prepare petal-shaped CuO / CeO2 nanosheet composite materials.

[0176] Take 20 mg of the petal-shaped CuO nanosheets prepared in the first step, add 10.9 mg of cerium nitrate hexahydrate, 2 mL of ethanol and 0.2 mL of water, sonicate in an ultrasonicator for 2 h, then dry the solvent in a vacuum drying oven, scrape off and place in a magnetic boat, heat to 400℃ in a muffle furnace for 18 min and hold for 1 h, then immediately remove and allow to cool to room temperature, collect the product by centrifugation at 8000 r / min, wash twice with water and ethanol (water to ethanol volume ratio of 1:1), and obtain the copper-cerium composite material. Its TEM image is shown below. Figure 7As shown, the copper-cerium composite material has a petal-like morphology and consists of relatively thin two-dimensional nanosheets. It is relatively uniform overall, with a lateral dimension of approximately 700 nm to 1.1 μm.

[0177] Comparative Example 1

[0178] 438.2 mg of copper nitrate was added to a 1000 mL beaker containing 500 mL of water and stirred for 5 min to obtain a copper salt solution. 500 mL of water was measured into a volumetric flask, and 98 μL of ethanolamine was added dropwise twice. The mixture was stirred for 5 min to obtain a reducing agent solution. The reducing agent solution was poured into the copper salt solution, stirred, and the reduction reaction was carried out at 25 °C for 12 h in a drying oven. After naturally cooling to room temperature, the product was collected by centrifugation at 8000 r / min, and washed twice with water and ethanol (water to ethanol volume ratio 1:1) to obtain CuO nanosheets. The TEM image of the nanosheets is shown below. Figure 8 As shown, the copper-cerium composite material has a leaf-like morphology and consists of thin two-dimensional nanosheets with a smooth and flat surface.

[0179] XPS spectra of copper in the copper-cerium composite material prepared in Example 1 and the CuO nanosheets prepared in Comparative Example 1 are shown below. Figure 9 As shown, the horizontal axis represents binding energy, and the vertical axis represents intensity. XPS spectral analysis results show that the copper valence state in both the copper-cerium composite material prepared in Example 1 and the CuO nanosheets prepared in Comparative Example 1 is +2, indicating that the valence state of copper did not change after loading cerium oxide. Compared with the CuO nanosheets prepared in Comparative Example 1, the peaks of each orbital of copper in the copper-cerium composite material prepared in Example 1 are mainly shifted to the right by 0.3 eV, which means that a rich interface was generated, and the interface interaction induced the rearrangement of copper electrons.

[0180] XPS spectra of cerium in the copper-cerium composite material prepared in Example 1 and the CuO nanosheets prepared in Comparative Example 1 are shown below. Figure 10 As shown, the horizontal axis represents binding energy, and the vertical axis represents intensity. XPS spectral analysis results show that the CuO nanosheets prepared in Comparative Example 1 do not contain cerium, while the copper-cerium composite material prepared in Example 1 shows peaks of different orbitals of cerium, mainly the peak of the +4 valence state in cerium oxide.

[0181] Comparative Example 2

[0182] Step 1: Preparation of CeO2

[0183] Dissolve 5 mmol of cerium nitrate hexahydrate in 20 mL of water, add 55 mL of 7 M NaOH solution dropwise, stir at room temperature for 30 min, then transfer to a reaction vessel and react at 130 °C for 5 h. After naturally cooling to room temperature, collect the product by centrifugation at 8000 r / min, wash twice with water and ethanol (water and ethanol volume ratio of 1:1) to obtain CeO2 nanorods.

[0184] Step 2: Using CeO2 nanorods as templates, prepare CuO / CeO2 nanosheet composite materials.

[0185] Take 20 mg of CeO2 nanorods prepared in the first step and sonicate them in 10 mL of water for 10 min. Add 13.4 mg of copper nitrate pentahydrate, then add 0.5 M sodium carbonate solution to adjust the pH to 9. Age at room temperature for one hour, then dry and keep at 600℃ for 4 h in an air atmosphere in a tube furnace. Immediately take it out and let it cool naturally to room temperature. Collect the product by centrifugation at 8000 r / min, and wash it twice with water and ethanol (water and ethanol volume ratio of 1:1) to obtain CuO / CeO2 nanorod composite material.

[0186] Comparative Example 3

[0187] 438.2 mg of copper nitrate was added to a 1000 mL beaker containing 500 mL of water and stirred for 5 min to obtain a copper salt solution. 500 mL of water was measured into a volumetric flask, and 98 μL of 1 g / mL ascorbic acid AA solution was added dropwise twice. The mixture was stirred for 5 min to obtain a reducing agent solution. The reducing agent solution was poured into the copper salt solution, stirred, and the reduction reaction was carried out in a drying oven at 25 °C for 12 h. The results showed that when ethanolamine was replaced with ascorbic acid AA, no CuO nanosheets were obtained.

[0188] The composite materials prepared in each embodiment and Comparative Example 2, as well as the CuO nanosheets prepared in Comparative Example 1, were used as catalysts for the electrocatalytic reduction of carbon dioxide in acidic media, as detailed below:

[0189] The electrocatalytic reduction of carbon dioxide in an acidic medium was carried out in a flow-through electrolyzer with a three-electrode system. The cathode and anode were separated by a proton exchange membrane. A homogeneous catalyst slurry was formed by ultrasonically mixing 4 mg of composite material or CuO nanosheets, 500 μL of methanol, and 10 μL of Nafion solution (5 wt%). This slurry was then drop-coated onto two commercially available 30T carbon paper sheets to form the working electrodes. An Ag / AgCl electrode was selected as the reference electrode, and the anode was a titanium mesh supported on iridium oxide. The cathode electrolyte was a 0.5 mM H₂SO₄ aqueous solution containing 3 M KCl, and the anode electrolyte was 0.5 M H₂SO₄. The carbon dioxide was electrolyzed and reduced under constant voltage, with carbon dioxide gas continuously introduced during the electrolysis process.

[0190] The product distribution of the copper-cerium composite material prepared in Example 1 as a catalyst for the electrocatalytic reduction of carbon dioxide at different voltages is shown in the figure below. Figure 11 As shown, the horizontal axis "potential" refers to electrical potential, and the vertical axis "Farada efficiency" represents Faraday efficiency. Figure 11 The display shows that at -1.5 v RHE, C 2+ The Faradaic efficiency of (including HOAc, n-PrOH, C2H5OH, C2H4) is 88%, that of ethanol (C2H5OH) is 48%, and that of ethylene (C2H4) is the highest at 34%. 2+ The Faradaic efficiency for alcohols (including n-PrOH and C2H5OH) is 53.9%, and the current density for ethanol is 344 mA cm⁻¹. -2 C 2+ The current density is 629 mA cm⁻¹ -2 This indicates that the copper-cerium composite material prepared in Example 1 has good selectivity and activity towards C2 addition products, especially towards ethanol.

[0191] The product distribution of the copper-cerium composite material prepared in Example 2 as a catalyst for the electrocatalytic reduction of carbon dioxide at different voltages is shown below. Figure 12 As shown, the horizontal axis represents potential, and the vertical axis represents Faraday efficiency. Figure 12 The display shows that at different potentials (-1.4V vs .RHE ~ -1V vs .RHE), C 2+ The highest Faraday efficiency was 75.4%, while the highest Faraday efficiency for ethanol was 31.2%. C 2+ The highest Faraday efficiency for alcohols is 31.2%, for ethylene it is 38.7%, and for hydrogen (H2) it is 17.3%.

[0192] The product distribution of the copper-cerium composite material prepared in Example 3 as a catalyst for the electrocatalytic reduction of carbon dioxide at different voltages is shown below. Figure 13 As shown, the horizontal axis represents potential, and the vertical axis represents Faraday efficiency. Figure 13 The display shows that at different potentials (-1.5V vs .RHE ~ -1V vs .RHE), C 2+ The highest Faraday efficiency was 65.12%, while the highest Faraday efficiency for ethanol was 29.6%. (C) 2+The highest Faraday efficiency for alcohols is 29.6%, for ethylene it is 28%, and for hydrogen (H2) it is 14.8%.

[0193] The product distribution of the copper-cerium composite material prepared in Example 4 as a catalyst for the electrocatalytic reduction of carbon dioxide at different voltages is shown below. Figure 14 As shown, the horizontal axis represents potential, and the vertical axis represents Faraday efficiency. Figure 14 The display shows that at different potentials (-1.55V vs .RHE ~ -1V vs .RHE), C 2+ The highest Faraday efficiency is 86.8%, while the highest Faraday efficiency of ethanol is 30.5%. (C) 2+ The highest Faradaic efficiency for alcohols is 36.6%, for ethylene it is 50.2%, for hydrogen (H2) it is 16.1%, and for ethanol it is 136 mAcm⁻¹. -2 C 2+ The maximum current density is 164 mA cm⁻¹ -2 .

[0194] The product distribution of CuO nanosheets prepared in Comparative Example 1 as a catalyst for the electrocatalytic reduction of carbon dioxide at different voltages is shown in the figure. Figure 15 As shown, the horizontal axis represents potential, and the vertical axis represents Faraday efficiency. Figure 15 The results show that hydrogen and carbon monoxide have high Faraday efficiencies, and ethylene accounts for the majority of the products. At -1.5 v RHE, C 2+ The Faraday efficiency is 75%, that of ethanol is 25.7%, that of ethylene is 45%, and that of hydrogen (H2) is 17%. The maximum current density of ethanol is 181 mA cm⁻¹. -2 C 2+ The maximum current density is 181.2 mA cm⁻¹. -2 .

[0195] The product distribution of the copper-cerium composite material prepared in Comparative Example 2 as a catalyst for the electrocatalytic reduction of carbon dioxide at different voltages is shown in the figure below. Figure 16 As shown, the horizontal axis represents potential, and the vertical axis represents Faraday efficiency. Figure 16 The display shows that at different potentials (-1.4 V vs .RHE ~ -1.14 V vs .RHE), C 2+ The highest Faraday efficiency was 14.9%, while the highest Faraday efficiency for ethanol was 7.9%. C2+ The highest Faraday efficiency for alcohol was 7.9%, for ethylene it was 8.98%, and for hydrogen (H2) it was 45.6%, indicating that the copper-cerium composite material prepared in Comparative Example 2 exhibited severe hydrogen evolution and very low selectivity for ethanol.

[0196] The current stability curves and Faraday efficiency for ethanol of the copper-cerium composite material prepared in Example 1 under constant voltage mode in the electrocatalytic carbon dioxide reduction reaction in acidic medium are shown below. Figure 17 As shown, the horizontal axis Time represents time, and the vertical axis j represents current density. Figure 17 The results show that the copper-cerium composite material prepared in Example 1 can operate under acidic conditions for 25 hours with almost no decrease in current density and maintains a selectivity for ethanol of over 38%.

[0197] Figure 18 The crossover ratio is the ratio of liquid products detected in the anolyte of the copper-cerium composite material prepared in Example 1 in an acidic medium. The vertical axis represents the cross-contamination ratio. Figure 18 The results show that the cross-contamination rate of transmembrane liquid products using Nafion membranes is significantly lower than that using AEM membranes in alkaline electrolytes. The anodic cross-contamination rate of various products is less than 5%, indicating that the cross-contamination of liquid products into the anode chamber can be effectively avoided or reduced in acidic systems, and liquid products can be analyzed and separated at the cathode electrolyte end.

[0198] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0199] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. The application of an electrocatalyst as a catalyst in the electrochemical reduction of carbon dioxide, characterized in that, The electrocatalyst comprises a copper-cerium composite material, and the preparation method of the copper-cerium composite material includes the following steps: Copper oxide material is prepared by mixing copper salt, reducing agent and first solvent and then carrying out a reduction reaction; the reducing agent includes ethanolamine; the temperature of the reduction reaction is 20℃~50℃. The copper oxide material and cerium salt are mixed and calcined to prepare a copper-cerium composite material; the mass ratio of the cerium salt to the copper oxide material is (0.4~0.6):1; the morphology of the copper-cerium composite material is leaf-shaped.

2. The application as described in claim 1, characterized in that, The reduction reaction is carried out at a temperature of 20℃ to 40℃.

3. The application as described in claim 1, characterized in that, The reduction reaction takes 6 h to 24 h.

4. The application as described in any one of claims 1 to 3, characterized in that, The preparation method satisfies at least one of the following characteristics: (1) The copper salt includes at least one of copper nitrate, copper chloride and copper sulfate; (2) The cerium salt includes at least one of cerium nitrate, cerium chloride, and cerium sulfate; (3) The first solvent includes water; (4) The volume ratio of the reducing agent to the mass ratio of the copper salt is (0.2~0.8) μL / mg; (5) The calcination treatment is carried out at a temperature of 300℃~500℃ for a time of 0.5 h~5 h.

5. The application as described in any one of claims 1 to 3, characterized in that, The steps of mixing copper oxide material and cerium salt and then calcining include: The copper oxide material, the cerium salt, and the second solvent are mixed and ultrasonicated, then dried to obtain a copper-cerium mixed material. The copper-cerium mixture is subjected to calcination treatment.

6. The application as described in claim 5, characterized in that, The second solvent includes at least one of ethanol and water.

7. The application as described in any one of claims 1 to 3, 6, characterized in that, In the copper-cerium composite material, the amount of cerium atoms accounts for 5% to 20% of the total amount of cerium atoms and copper atoms.

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