Electrochemical catalyst for carbon dioxide reduction and synthetic method and application thereof

Abstract

The invention discloses an electrochemical catalyst for carbon dioxide reduction and a synthesis method and application thereof. The catalyst comprises a carrier and cuprous oxide, the cuprous oxide is in a spherical shape; the carrier is a titanium carbide MXene multilayer nanosheet. The catalyst is used in the electrochemical reduction reaction of carbon dioxide, and has the advantages of simple and non-toxic preparation process and high current density generated in the reaction process.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical catalysts for carbon dioxide reduction, specifically relating to an electrochemical catalyst for carbon dioxide reduction, its synthesis method, and its application. Background Technology

[0002] Converting carbon dioxide into high-value-added chemicals using clean energy can alleviate energy shortages while reducing atmospheric carbon dioxide levels. Among various carbon dioxide reduction methods, electrocatalytic reduction offers mild operating conditions and is a green and easily scalable strategy. The inert C=O bond breaks to form C=C or CH bonds, which are then converted into various alkanes, hydrocarbons, other chemicals, and high-value-added carbon-based fuels through the transfer of two, four, six, or even eight electrons. For decades, carbon dioxide reduction electrodes in aqueous or ionic liquid-based solutions have consistently been made of metals, metal oxides, and carbon-based materials. The catalyst supported on the electrode directly determines the type and efficiency of the carbon dioxide conversion products through its morphological properties and conductivity.

[0003] Among numerous catalysts, copper-based materials can convert carbon dioxide gas into multi-carbon products. As a class of p-type transition metal oxides, cuprous oxide exhibits unique physical and chemical properties in the fields of electricity, magnetism, and catalysis, and is widely used in important areas such as printing and dyeing, ceramics, electrode active materials, and catalysts. Two-dimensional transition metal carbides, nitrides, and carbonitrides (MXenes) have high CO2 capture capabilities, which is related to the high specific surface area and numerous adsorption sites of MXenes.

[0004] CN118341488A discloses a Ti3C2T x MXene-supported copper-aluminum nanoalloy catalyst, its preparation method, and its application. This catalyst reduces the overpotential of CO2 reduction and improves energy efficiency in the electrocatalytic carbon dioxide reduction reaction; however, its toxicity needs to be considered during the MXene etching process. Furthermore, it also suffers from serious hydrogen evolution reaction problems and complex preparation processes.

[0005] Therefore, the electrocatalytic performance of existing process catalysts used in electrocatalytic carbon dioxide reduction reactions still needs to be further improved. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides an electrochemical catalyst for carbon dioxide reduction, its synthesis method, and its application. This catalyst, used in the electrochemical reduction reaction of carbon dioxide, has the advantages of a simple and non-toxic preparation process and the generation of a high current density during the reaction.

[0007] The first aspect of this invention provides an electrochemical catalyst for carbon dioxide reduction. The catalyst comprises: a support and cuprous oxide; the cuprous oxide has a spherical morphology; the support is titanium carbide (Ti3C2T). x MXene multilayer nanosheets.

[0008] According to the present invention, the particle size of the cuprous oxide is 100-210 nm, preferably 140-200 nm.

[0009] According to the present invention, the carrier is titanium carbide (Ti3C2T). x MXene multilayer nanosheets.

[0010] According to the present invention, in the catalyst, 20 to 50 (preferably 20 to 40) cuprous oxide atoms are loaded on each square micrometer support.

[0011] According to the present invention, based on the mass of the catalyst, the support accounts for 20 wt% to 43 wt%, preferably 30 wt% to 43 wt%, and cuprous oxide accounts for 57 wt% to 80 wt%, preferably 57 wt% to 70 wt%.

[0012] A second aspect of the present invention provides a method for preparing the catalyst. The method includes the step of loading cuprous oxide onto a support by an impregnation method.

[0013] According to the present invention, preferably, in the method for preparing the catalyst, cuprous oxide is first dispersed in water to obtain a dispersion; then the support is impregnated into the dispersion.

[0014] According to the present invention, the impregnation is carried out under stirring. The stirring rate is 400–1000 r / min. The impregnation time is 6–11 h.

[0015] According to the present invention, the ratio of cuprous oxide to water is 1 mg: 1 to 3 ml.

[0016] According to the present invention, after impregnation, centrifugal washing and drying can be performed. The drying temperature is 50-70°C, and the drying time is 10-13 hours. The drying is vacuum drying. Preferably, the vacuum degree is -0.08 to -0.1 MPa.

[0017] According to the present invention, the cuprous oxide is prepared into spherical cuprous oxide by a polyol-assisted method.

[0018] According to the present invention, more preferably, the method for preparing the cuprous oxide includes:

[0019] A reducing agent, a dispersant, and a copper precursor are mixed and reacted to obtain spherical cuprous oxide.

[0020] According to the present invention, the reducing agent is diethylene glycol. The dispersant is polyvinylpyrrolidone. The copper precursor is copper nitrate. The mass ratio of the reducing agent, dispersant and copper precursor is 69-100:6.8-11:1, preferably 69-95:6.8-10:1.

[0021] According to the present invention, preferably, before the reaction, the reaction system is evacuated to a vacuum and maintained for 10 to 20 minutes.

[0022] According to the present invention, the reaction conditions are as follows: the reaction atmosphere is an inert atmosphere, preferably nitrogen and / or a rare gas; the rare gas is preferably argon. The reaction temperature is 180–200°C; the reaction time is 25–35 min; and the reaction pressure is 0.05–0.1 MPa.

[0023] According to the present invention, the reaction is followed by cooling to 10–30°C. The cooling rate is 1–5°C / min. After the reaction, the product is washed by centrifugation. The centrifugation conditions are: rotation speed 9000–11000 rpm, time 2–5 min. The washing solution is at least one of water and alcohol. Ethanol is preferred. Preferably, the product is washed first with water, then with alcohol. After separation, the product can be dried. The drying conditions are: drying temperature 40–60°C; drying time 10–12 h. The drying is vacuum drying. The vacuum degree is -0.08 to -0.1 MPa.

[0024] According to the present invention, the carrier can be commercially available or domestically manufactured.

[0025] A third aspect of the present invention provides the application of the catalyst in the electrochemical reduction reaction of CO2.

[0026] According to the present invention, in the application, CO2 is converted into CO, C2H4, and HCOOH.

[0027] According to the present invention, the application employs a three-electrode system. Preferably, an H-type electrochemical cell is used. The electrochemical reduction reaction is carried out in a potassium bicarbonate electrolyte. The catalyst is used as the working electrode, a platinum electrode as the counter electrode, and an Ag / AgCl electrode as the reference electrode.

[0028] According to the present invention, in the application described, the CO2 flow rate is 20–30 sccm / mg catalyst.

[0029] Compared with the prior art, the main advantages of the present invention include:

[0030] 1. The catalyst of the present invention comprises: a support and cuprous oxide; the cuprous oxide has a spherical morphology; the support is titanium carbide (Ti3C2T). xMXene multilayer nanosheets. The support and cuprous oxide work synergistically to create a catalyst for the electrochemical reduction of carbon dioxide. This catalyst has the advantages of simple and non-toxic preparation process and high current density generated during the reaction.

[0031] Preferably, the present invention further improves the electrocatalytic performance of the catalyst in the reaction by controlling the particle size (100-200 nm) of spherical cuprous oxide in the catalyst and the loading of cuprous oxide per unit square micrometer (20-40 particles). A low quantity of cuprous oxide is detrimental to increasing the current density, while a high quantity results in an excessively high onset potential, which is unfavorable for the CO2 electrocatalytic reaction.

[0032] Preferably, the catalyst of the present invention uses a support containing vacancies formed by the absence of titanium atoms, with more than two atomic defect vacancies per square nanometer of support. Its structure is two-dimensional and layered, exhibiting high electrical conductivity and thermal stability, and possessing abundant surface functional groups and tunable electronic properties. The support, in conjunction with cuprous oxide, enhances the electrocatalytic performance of the catalyst.

[0033] 2. The preparation method of the catalyst of the present invention is simple. Spherical cuprous oxide is prepared by polyol-assisted method, and cuprous oxide is loaded on the support by impregnation method. The preparation process is simple and does not require any complicated equipment. It is a simple, efficient and inexpensive catalyst preparation method.

[0034] In the preparation method of the catalyst of the present invention, preferably, the morphology of cuprous oxide is controlled by adjusting the feeding ratio of reducing agent, dispersant and copper precursor to obtain spherical cuprous oxide particles with a particle size of 100-200 nm; and these particles have a suitable distribution density on the support. This catalyst can increase the current density in the CO2 electrocatalytic reaction while maintaining a low onset potential.

[0035] 3. The catalyst of this invention can be applied to the electrochemical reduction reaction of CO2 to prepare high-value-added chemicals, which helps to realize the closed carbon cycle, reduce the greenhouse effect and alleviate global warming. Attached Figure Description

[0036] Figure 1 and Figure 2 Transmission electron microscope image of the sample prepared in Example 1;

[0037] Figure 3 The XRD pattern of the sample prepared in Example 1;

[0038] Figure 4 Transmission electron microscope image of the sample obtained in Example 2;

[0039] Figure 5 The image is a transmission electron microscope (TEM) image of the sample prepared in Comparative Example 1.

[0040] Figure 6 The graphs show the polarization curves of the carbon dioxide reduction reaction for each example. Detailed Implementation

[0041] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0042] Any range described in this invention includes the endpoint, any value between the endpoints, and any subrange consisting of the endpoint or any value between the endpoints.

[0043] In this invention, the current density testing methods mainly include the following steps:

[0044] 1) Preparation of the working electrode: Weigh 2 mg of the catalyst prepared in this invention, then add 150 μL of isopropanol, 150 μL of deionized water and 10 μL of Nafion solution (mass fraction of 5%), and ultrasonically disperse for 15 minutes to obtain a dispersion. Then, drop-coat the dispersion onto 2*1 cm carbon paper under a 60℃ baking lamp, and let it air dry naturally to serve as the working electrode.

[0045] 2) Electrocatalytic carbon dioxide reduction reaction (i.e., current density measurement) was conducted using an H-type electrolytic cell as the reactor on a Shanghai Chenhua 760E electrochemical workstation. A platinum sheet electrode was used as the counter electrode, and an Ag / AgCl electrode as the reference electrode. 0.1 mol / L KHCO3 was used as the electrolyte. The relationship curve between catalyst current and potential (polarization curve) was recorded using linear voltammetry on the 760E electrochemical workstation at a scan rate of 0.005 V / s and a voltage range of -1.5 V to -0.4 V (vs. RHE).

[0046] 3) Before the test, CO2 gas was introduced into the H-type electrolytic cell for 30 minutes to purge the air from the cell and obtain a CO2-saturated KHCO3 electrolyte. The CO2 flow rate was 30 sccm / mg catalyst.

[0047] In this invention, the room temperature described in each example is 20°C.

[0048] In this invention, the particle size is measured using a transmission electron microscope (TEM - 120kV). The particle size is the average particle size.

[0049] In this invention, the carrier in each example is titanium carbide (Ti3C2T). x MXene multilayer nanosheets were purchased from Maclean's Reagents, model number T916421.

[0050] Example 1

[0051] Preparation of spherical cuprous oxide:

[0052] 1) Add 3g of polyvinylpyrrolidone, 30g of diethylene glycol and 360mg of copper nitrate trihydrate to a three-necked flask and degas under vacuum for 15 minutes.

[0053] 2) After introducing nitrogen, heat to 190℃ and maintain at 0.07MPa and 190℃ for 30 minutes.

[0054] 3) After cooling to room temperature at a cooling rate of 3℃ / min, wash sequentially with deionized water and ethanol by centrifugation. Centrifugation conditions: 10000 rpm for 3 min. Spherical cuprous oxide is obtained by drying in a vacuum drying oven. The drying conditions are: drying temperature 60℃, vacuum degree -0.1 MPa, and drying time 12 h.

[0055] Catalyst preparation:

[0056] 20 mg of spherical cuprous oxide was dispersed in 40 mL of deionized water to obtain a dispersion. Then 10 mg of (Ti3C2T) was taken... x MXene was added to the dispersion and stirred at room temperature for 10 hours at a stirring rate of 800 r / min. The product was then washed sequentially with deionized water and ethanol by centrifugation, and dried in a vacuum drying oven to obtain the catalyst. The drying temperature was 60℃, the vacuum degree was -0.1 MPa, and the drying time was 12 h.

[0057] The cuprous oxide has a particle size of 150 nm.

[0058] In the catalyst, 25 cuprous oxide atoms are loaded on the support per square micrometer.

[0059] Figure 2 and Figure 3 The transmission electron microscope (TEM) image of the catalyst prepared in Example 1 shows that spherical cuprous oxide is distributed in (Ti3C2T) x MXene surface.

[0060] Figure 4 The XRD pattern of the catalyst prepared in Example 1 shows the diffraction peaks of Cu2O, indicating that spherical cuprous oxide is loaded on MXene.

[0061] The catalyst prepared in this example exhibits a maximum current density of 224 mA / cm² when used for the electroreduction of carbon dioxide. 2 .

[0062] Example 2

[0063] Preparation of spherical cuprous oxide:

[0064] 1) Add 2.7g of polyvinylpyrrolidone, 25g of diethylene glycol and 360mg of copper nitrate trihydrate to a three-necked flask and degas under vacuum for 15 minutes.

[0065] 2) After introducing nitrogen, heat to 190℃ and maintain at 0.07MPa and 190℃ for 30 minutes.

[0066] 3) After cooling to room temperature at a cooling rate of 5℃ / min, wash sequentially with deionized water and ethanol by centrifugation. Centrifugation conditions: 10000 rpm for 5 min. Spherical cuprous oxide is obtained by drying in a vacuum drying oven. The drying conditions are: drying temperature 60℃, vacuum degree -0.1 MPa, and drying time 11 h.

[0067] Catalyst preparation:

[0068] 20 mg of spherical cuprous oxide was dispersed in 40 mL of deionized water to obtain a dispersion. Then 10 mg of (Ti3C2T) was taken... x MXene was added to the dispersion and stirred at room temperature for 9 hours at a stirring rate of 800 r / min. The product was then washed sequentially with deionized water and ethanol by centrifugation, and dried in a vacuum drying oven to obtain the catalyst. The drying temperature was 60℃, the vacuum degree was -0.1 MPa, and the drying time was 12 h.

[0069] The cuprous oxide has a particle size of 170 nm.

[0070] In the catalyst, 35 cuprous oxide atoms are loaded on the support per square micrometer.

[0071] The catalyst prepared in this example exhibits a maximum current density of 230 mA / cm² when used for the electroreduction of carbon dioxide. 2 .

[0072] Example 3

[0073] Preparation of spherical cuprous oxide:

[0074] 1) Add 3.5g of polyvinylpyrrolidone, 35g of diethylene glycol and 370mg of copper nitrate trihydrate to a three-necked flask and degas under vacuum for 15 minutes.

[0075] 2) After introducing nitrogen, heat to 195℃ and maintain at 0.07MPa and 195℃ for 30 minutes.

[0076] 3) After cooling to room temperature at a cooling rate of 4℃ / min, wash sequentially with deionized water and ethanol by centrifugation. Centrifugation conditions: 10000 rpm for 5 min. Spherical cuprous oxide is obtained by drying in a vacuum drying oven. The drying conditions are: drying temperature 60℃, vacuum degree -0.1 MPa, and drying time 12 h.

[0077] Catalyst preparation:

[0078] 20 mg of spherical cuprous oxide was dispersed in 40 mL of deionized water to obtain a dispersion. Then 12 mg of (Ti3C2T) was taken... x MXene was added to the dispersion and stirred at room temperature for 9 hours at a stirring rate of 800 r / min. The product was then washed sequentially with deionized water and ethanol by centrifugation, and dried in a vacuum drying oven to obtain the catalyst. The drying temperature was 60℃, the vacuum degree was -0.1 MPa, and the drying time was 12 h.

[0079] The cuprous oxide has a particle size of 140 nm.

[0080] In the catalyst, 40 cuprous oxide atoms are loaded on each square micrometer of support.

[0081] The catalyst prepared in this example exhibits a maximum current density of 222 mA / cm² when used for the electroreduction of carbon dioxide. 2 .

[0082] Example 4

[0083] Preparation of spherical cuprous oxide:

[0084] 1) Add 2.5g of polyvinylpyrrolidone, 30g of diethylene glycol and 360mg of copper nitrate trihydrate to a three-necked flask and degas under vacuum for 15 minutes.

[0085] 2) After introducing nitrogen, heat to 190°C and maintain at 0.07 MPa and 190°C for 30 minutes.

[0086] 3) After cooling to room temperature at a cooling rate of 5℃ / min, wash sequentially with deionized water and ethanol by centrifugation. Centrifugation conditions: 10000 rpm for 5 min. Then dry in a vacuum drying oven to obtain spherical cuprous oxide. The drying conditions are: drying temperature 60℃, vacuum degree -0.1 MPa, and drying time 12 h.

[0087] Catalyst preparation:

[0088] 20 mg of spherical cuprous oxide was dispersed in 40 mL of deionized water to obtain a dispersion. Then 10 mg of (Ti3C2T) was taken... x MXene was added to the dispersion and stirred at room temperature for 6 hours at a stirring rate of 800 r / min. The product was then washed sequentially with deionized water and ethanol by centrifugation, and dried in a vacuum drying oven to obtain the catalyst. The drying temperature was 60℃, the vacuum degree was -0.1 MPa, and the drying time was 12 h.

[0089] The cuprous oxide has a particle size of 190 nm.

[0090] In the catalyst, 40 cuprous oxide atoms are loaded on each square micrometer of support.

[0091] The catalyst prepared in this example exhibits a maximum current density of 240 mA / cm² when used for the electroreduction of carbon dioxide. 2 .

[0092] Example 5

[0093] The difference from Example 1 lies in the raw material feeding ratio in the preparation of cuprous oxide. In this example, the amount of polyvinylpyrrolidone added is 4g. Furthermore, in the preparation of the catalyst, 30mg of spherical cuprous oxide is dispersed in 40mL of deionized water to obtain a dispersion, and then 10mg of (Ti3C2T) is added... x MXene was added to the dispersion. The rest was the same as in Example 1.

[0094] The cuprous oxide has a particle size of 210 nm.

[0095] In the catalyst, 50 cuprous oxide atoms are loaded on each square micrometer of support.

[0096] The catalyst prepared in this example exhibits a maximum current density of 190 mA / cm² when used for the electroreduction of carbon dioxide. 2 .

[0097] Comparative Example 1

[0098] Preparation of cuprous oxide:

[0099] 1) Add 1.5g polyvinylpyrrolidone, 30g diethylene glycol and 360mg copper nitrate trihydrate to a three-necked flask and degas under vacuum for 15 minutes.

[0100] 2) After introducing nitrogen, heat to 190℃ and maintain at 0.07MPa and 190℃ for 30 minutes.

[0101] 3) After cooling to room temperature at a cooling rate of 3℃ / min, the catalyst is washed sequentially by centrifugation with deionized water and ethanol. The centrifugation conditions are: 10000 rpm for 3 min. The catalyst is then dried in a vacuum drying oven to obtain cuprous oxide catalyst. The drying conditions are: drying temperature 60℃, vacuum degree -0.1 MPa, and drying time 12 h.

[0102] Catalyst preparation:

[0103] The catalyst was prepared in the same manner as in Example 1.

[0104] In this example, the cuprous oxide particles are polyhedral in shape and have an irregular morphology. The particle size is 1 μm. In the catalyst, 5 cuprous oxide particles are loaded per square micrometer of support.

[0105] In this example, the catalyst, when used for the electroreduction of carbon dioxide, exhibits a maximum current density of 47.5 mA / cm². 2 .

[0106] Comparative Example 2

[0107] Comparative Example 2 prepared a Ti3C2T x MXene-supported copper-aluminum nano-alloy catalyst. The catalyst was prepared using the method described in Example 1 of CN118341488A. When used in the electrocatalytic reaction of CO2, the maximum current density was 60 mA / cm². 2 .

[0108] Comparative Example 3

[0109] Preparation of spherical cuprous oxide:

[0110] The preparation of spherical cuprous oxide is the same as in Example 1.

[0111] In this example, the spherical cuprous oxide (without a support) is directly used in the carbon dioxide electroreduction reaction.

[0112] In this example, the catalyst is used for the electroreduction of carbon dioxide, with a maximum current density of 100 mA / cm². 2 .

[0113] Comparative Example 4

[0114] Preparation of cuprous oxide:

[0115] 1) Add 4.2g of polyvinylpyrrolidone, 30g of diethylene glycol and 360mg of copper nitrate trihydrate to a three-necked flask and degas under vacuum for 15 minutes.

[0116] 2) After introducing nitrogen, heat to 190℃ and maintain at 0.07MPa and 190℃ for 30 minutes.

[0117] 3) After cooling to room temperature at a cooling rate of 3℃ / min, the catalyst is washed sequentially by centrifugation with deionized water and ethanol, and then dried in a vacuum drying oven to obtain the cuprous oxide catalyst. The centrifugation conditions are: 10000 rpm for 3 min. The drying conditions are: drying temperature of 60℃, vacuum degree of -0.1 MPa, and drying time of 12 h.

[0118] Catalyst preparation:

[0119] The catalyst was prepared in the same manner as in Example 1.

[0120] In this example, the cuprous oxide is in irregular block form with a particle size of 1 μm. In the catalyst, two cuprous oxide particles are loaded per square micrometer of support.

[0121] In this example, the catalyst, when used for the electroreduction of carbon dioxide, exhibits a maximum current density of 66.39 mA / cm². 2 .

[0122] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. An electrochemical catalyst for carbon dioxide reduction, comprising: Carrier and cuprous oxide; the cuprous oxide has a spherical morphology; the carrier is titanium carbide (Ti3C2T x ) MXene multilayer nanosheet.

2. The catalyst of claim 1, wherein The cuprous oxide has a particle size of 100-210 nm, preferably 140-200 nm. And / or, in the catalyst, 20-50 (preferably 20-40) cuprous oxides are loaded on each square micron of the carrier.

3. The catalyst of claim 1, wherein The carrier accounts for 20wt%-43wt%, preferably 30wt%-43wt%, and the cuprous oxide accounts for 57wt%-80wt%, preferably 57wt%-70wt%, based on the mass of the catalyst.

4. Process for the preparation of the catalyst according to any one of claims 1 to 3, characterized in that, The method comprises the step of loading cuprous oxide on the carrier by impregnation.

5. The method of claim 4, wherein, The preparation method of the cuprous oxide comprises mixing a reducing agent, a dispersing agent and a copper precursor, and performing a reaction to obtain spherical cuprous oxide.

6. The method of claim 5, wherein, The reducing agent is diethylene glycol; and / or the dispersing agent is polyvinylpyrrolidone; and / or the copper precursor is copper nitrate.

7. The method of claim 5 or 6, wherein, The mass ratio of the reducing agent, the dispersing agent and the copper precursor is 69-100:6.8-11:1, preferably 69-95:6.8-10:

1.

8. The method of claim 5, wherein, The reaction conditions are as follows: the reaction atmosphere is inert atmosphere; and / or the reaction temperature is 180-200℃; and / or the reaction time is 25-35 min; and / or the reaction pressure is 0.05-0.1 MPa.

9. Use of the catalyst of any one of claims 1-3 or the catalyst prepared by the method of any one of claims 4-8 in a CO2 electrochemical reduction reaction.

10. Use according to claim 9, characterized in that, In the use, CO2 is converted into CO, C2H4 and HCOOH.

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