A B-doped CuO nanotube catalytic material for electrocatalytic CO2 reduction to C2 products and its preparation method

Abstract

The present invention discloses a B-doped CuO nanotube catalytic material for electrocatalytic CO2 reduction to C2 products and a preparation method thereof, belonging to the field of electrocatalytic technology. The preparation of the B-doped CuO nanotube catalytic material of the present invention is to prepare B-Cu precursor nanofibers by electrospinning technology, and then calcine at high temperature in an air atmosphere to obtain a B-doped CuO nanotube material. The method is simple to prepare and easy to operate. The raw materials used are inexpensive and easy to scale up. The prepared material has a high specific surface area and a large number of active sites, which are conducive to the adsorption of gases and the diffusion of reaction intermediates, and exhibits excellent electrocatalytic CO2 reduction performance. At the same time, B doping can optimize the electronic structure of CuO nanotubes and improve the selectivity of C2 products in their CO2 reduction, and has good application prospects in electrocatalytic CO2 reduction.

Description

Technical Field

[0001] The present invention relates to a B-doped CuO nanotube catalytic material for electrocatalytic CO2 reduction to produce C2 products and a preparation method thereof, belonging to the technical field of electrocatalysis. Background Art

[0002] The large-scale combustion of traditional fossil fuels (such as coal, oil, and natural gas) has led to excessive accumulation of CO2 gas, which has gradually caused environmental deterioration such as global warming, land desertification, and ocean acidification. Therefore, alleviating the impact of severe CO2 emissions has become a more urgent issue in today's society.

[0003] At present, electrocatalytic CO2 reduction is a process that turns CO2, a greenhouse gas, into valuable products by reducing it to alkane products. On the one hand, it can alleviate the environmental problems caused by the release of large amounts of CO2. On the other hand, it can obtain alkane products with higher added value, providing a new solution to the energy crisis caused by the consumption of large amounts of fossil fuels. It has attracted the attention of many researchers because of its advantages such as simple equipment, safety and high efficiency.

[0004] Cu-based catalytic materials have attracted much attention due to their abundant reserves and the fact that Cu is currently the only metal catalytic material that can reduce CO2 to multi-carbon products. However, their low catalytic efficiency and complex reduction products limit the application of Cu-based catalytic materials. Summary of the Invention

[0005] In response to the problems of poor product selectivity and low catalytic efficiency of Cu-based catalytic materials in the existing technology, the present invention aims to optimize the morphology and structure of Cu-based catalysts and design a catalytic material for efficient electrocatalytic CO2 reduction to C2 products.

[0006] The present invention specifically uses B-doped CuO nanotubes to prepare a catalytic material under specific process conditions. This method can effectively optimize the morphology and structure of the Cu-based catalytic material. By adjusting its electronic structure, its selectivity and catalytic efficiency in the process of producing C2 products in the electrocatalytic CO2 reduction are greatly improved. The method is simple to operate and low in cost. The prepared catalytic material exhibits excellent catalytic activity and stability, and has practical significance for wide application in the electrocatalytic CO2 reduction.

[0007] The first object of the present invention is to provide a method for preparing a B-doped CuO nanotube catalytic material for electrocatalytic CO2 reduction to C2 products, the method comprising the following steps:

[0008] (1) Preparation of hybrid nanofiber membranes

[0009] Copper source and boron source are added to the fiber precursor solution, magnetically stirred and then electrospinning is performed to obtain a mixed nanofiber membrane containing copper and boron.

[0010] (2) Preparation of B-doped CuO nanotube catalytic materials

[0011] The mixed nanofiber membrane prepared in step (1) is pre-oxidized and then calcined at 300-700° C. in an air atmosphere for 1-3 hours. After the insulation is completed, the mixture is naturally cooled to room temperature to obtain a B-doped CuO nanotube catalytic material B-CuO.

[0012] In one embodiment, in step (1), the boron source is one or both of boric acid and boron trioxide; the copper source is one or more of copper nitrate, copper chloride, and copper acetate.

[0013] In one embodiment, in step (1), the fiber precursor solution is a mixed solution of one or more of polyvinyl pyrrolidone, polyacrylonitrile, polyvinyl alcohol, and ethanol and / or N,N-dimethylformamide.

[0014] In one embodiment, in step (1), the solid content of the fiber precursor solution is 10-15 wt%.

[0015] In one embodiment, in step (1), the total mass of the copper source and the boron source is 20-60 wt % of the fiber precursor solution.

[0016] In one embodiment, in step (1), the molar ratio of the copper source to the boron source is 1:3 to 3:1.

[0017] In one embodiment, in step (1), the specific parameters of the electrospinning technology are set as follows: the spinning voltage is 10-25 kV, the distance from the receiving device to the needle is 10-20 cm, and the solution flow rate is 0.01-0.10 mL / min.

[0018] In one embodiment, in step (2), the temperature of the pre-oxidation treatment of the hybrid nanofiber membrane is 180-250°C, the heating rate is 1-10°C / min; the holding time is 1-3 hours; the pre-oxidation temperature is preferably 200°C, and the holding time is preferably 3 hours.

[0019] In one embodiment, in step (2), the temperature of high-temperature calcination of the hybrid nanofiber membrane is 400-600° C.; the holding time is 1-3 hours; preferably 500° C., and the holding time is 3 hours.

[0020] In one embodiment, in step (2), the heating rate is 1°C / min, 2°C / min, 5°C / min or 10°C / min; preferably 2°C / min or 5°C / min.

[0021] In one embodiment, the C2 comprises ethylene, ethane, ethanol, acetic acid.

[0022] The second object of the present invention is to provide a B-doped CuO nanotube catalytic material prepared by the above method.

[0023] The third object of the present invention is to provide a use of the above-mentioned B-doped CuO nanotube catalytic material in electrocatalytic CO2 reduction.

[0024] The fourth object of the present invention is to provide a method for electrocatalytic reduction of CO2 to produce C2 products, wherein the method utilizes the B-doped CuO nanotube catalytic material prepared above as a catalyst.

[0025] In one embodiment of the present invention, the method is specifically as follows: the B-doped CuO nanotube catalytic material described above is dissolved in ethanol, sprayed on conductive carbon paper as a working electrode, Ag / AgCl as a reference electrode, RuO2 as a counter electrode, and high-purity CO2 is continuously introduced for electrochemical reduction.

[0026] Beneficial effects of the present invention:

[0027] (1) The present invention adopts electrospinning technology to prepare nanofiber membranes. This method is simple to prepare and easy to operate. The raw materials used are inexpensive and easy to mass-produce. Moreover, using nanofibers as templates, this method can effectively maintain the one-dimensional nanostructure of the catalytic material and form a nanotube structure with a large surface area. The prepared B-doped CuO nanotubes exhibit a porous nanotube morphology, a large specific surface area, and a larger number of active sites on the surface, which can accelerate the reaction and improve its catalytic efficiency.

[0028] (2) The B-doped CuO nanotubes prepared in the present invention can effectively regulate the electronic structure of Cu, and electron transfer occurs between Cu and B atoms. The optimization of the electronic structure of the Cu surface can reduce the adsorption energy barrier of the reverse site for the C2 product intermediate, thereby improving its selectivity for the C2 product in the electrocatalytic CO2 reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Microscopic morphology of the B-CuO nanotube catalytic material prepared in Example 1 of the present invention; (a, b) field emission scanning electron microscopy images of B-CuO nanotubes; (c) transmission electron microscopy image of B-CuO nanotubes; (d) high-resolution transmission electron microscopy image of B-CuO nanotubes;

[0030] Figure 2 X-ray diffraction patterns of CuO and B-CuO nanotube catalytic materials prepared in Example 1 of the present invention;

[0031] Figure 3 The isotherm curve and pore size distribution curve of the B-CuO nanotube catalytic material prepared in Example 1 of the present invention; (a) N2 adsorption-desorption isotherm curve; (b) corresponding pore size distribution curve;

[0032] Figure 4 Graphs showing the electrocatalytic CO2 reduction performance of the B-CuO nanotube catalytic material prepared in Example 1 of the present invention in the presence of 1 mol / L KOH; (a) a graph showing the electrocatalytic CO2 reduction polarization curve of the B-CuO nanotube catalytic material; (b) a graph showing the C1 and C2 Faraday efficiencies of the B-CuO nanotube catalytic material; and (c) a graph showing the stability data of the B-CuO nanotube catalytic material.

[0033] Figure 5 Electrocatalytic CO2 reduction performance of the CuO nanotube catalytic material prepared in Comparative Example 1 under 1 mol / L KOH;

[0034] Figure 6 Micromorphology and reduction performance of the B-CuO nanobelt catalytic material prepared in Comparative Example 2; (a) Micromorphology; (b) Electrocatalytic CO2 reduction performance in 1 mol / L KOH;

[0035] Figure 7 Micromorphology and reduction performance diagram of the B-CuO nanofiber catalytic material prepared in Comparative Example 3; (a) micromorphology; (b) electrocatalytic CO2 reduction performance diagram under 1 mol / L KOH. DETAILED DESCRIPTION

[0036] In order to better understand the present invention, the content of the present invention is further illustrated below with reference to examples, but the content of the present invention is not limited to the examples given below.

[0037] 1. Test method for electrocatalytic CO2 reduction of catalytic materials in 1 mol / L KOH

[0038] The test was carried out using a gas diffusion electrolysis cell on an AutoLab electrochemical workstation. The catalytic material was dissolved in ethanol and sprayed on conductive carbon paper as the working electrode, Ag / AgCl as the reference electrode, and RuO2 as the counter electrode. High-purity CO2 was continuously introduced during the test. After a long reaction time, the gaseous product entered the chromatographic analysis, and the liquid product was detected by nuclear magnetic resonance.

[0039] Example 1

[0040] A method for preparing a B-doped CuO nanotube catalyst for electrocatalytic CO2 reduction to C2 products, the method comprising the following steps:

[0041] (1) 2 g of polyvinyl pyrrolidone powder was added to a mixed solution of 8 g of ethanol and 8 g of N,N-dimethylformamide, and after stirring evenly, 0.86 g of copper nitrate and 0.14 g of boric acid were added to the mixed solution (the total amount of metal salt was 1 g, and the molar ratio of copper nitrate to boric acid was 2:1). After stirring for 10 hours, a uniformly mixed ultrafine fiber precursor solution was obtained;

[0042] The precursor solution was then transferred to a syringe and spun using electrospinning technology. The control voltage was 18 kV, the distance from the syringe needle to the receiver was 18 cm, and the solution pushing speed was 0.01 mL / min. After continuous spinning for 24 hours, the precursor mixed nanofiber membrane was obtained.

[0043] (2) 0.2 g of the mixed nanofiber membrane prepared in step (1) was placed in a corundum boat, which was placed in the middle of a tubular furnace. The temperature was raised to 200°C at a heating rate of 2°C / min in an air atmosphere, and the temperature was kept in air for 3 hours for pre-oxidation treatment. The temperature was then raised at a heating rate of 2°C / min to 500°C and kept for 3 hours. After the insulation was completed, the temperature was naturally cooled to room temperature to obtain a B-CuO nanotube catalytic material.

[0044] Structural characterization:

[0045] Figure 1 This is the microscopic morphology of the B-CuO nanotube catalytic material, where: Figure 1 a, 1b are field emission scanning electron microscope images of B-CuO nanotubes. It can be seen from the figures that the prepared material has the morphology of porous nanotubes, and the one-dimensional nanotube structure is combined to form a three-dimensional network structure.

[0046] Figure 1 c is the transmission electron microscope image of B-CuO nanotubes, Figure 1 c further confirmed the nanotube morphology of B-CuO, and B-CuO nanotubes are composed of many tiny nanocrystals. Figure 1 d is the high-resolution transmission electron microscopy image of B-CuO nanotubes. Figure 1 d shows lattice fringes with spacings of 0.278 and 0.233 nm, corresponding to the (110) and (111) planes of CuO.

[0047] Figure 2 The X-ray diffraction patterns of CuO and B-CuO nanotube catalytic materials are shown in Figure 2. Figure 2It can be concluded that the diffraction peak of CuO corresponds well to the standard card (48-1548), and the doping of B does not change the phase of CuO, confirming that the prepared catalytic material has a CuO structure.

[0048] Figure 3 a is the N2 adsorption-desorption isotherm curve of B-CuO nanotube catalytic material, Figure 3 b is the corresponding pore size distribution curve. Figure 3 The BET surface area of ​​the B-CuO nanotube catalytic material is 23.2 m 2 ·g -1 , the pore size distribution is around 10 nm, which further confirms the porous structure of the B-CuO nanotube catalytic material.

[0049] Figure 4 is the electrocatalytic CO2 reduction performance of B-CuO nanotube catalytic material under 1 mol / L KOH, where Figure 4 a is the electrocatalytic CO2 reduction polarization curve of B-CuO nanotube catalytic material. It can be seen that compared with N2 atmosphere, B-CuO nanotube catalytic material has a larger current value in CO2 atmosphere, reaching 200mA / cm at -1V. 2 The above results show excellent electrocatalytic CO2 reduction performance. Figure 4 b is the Faraday efficiency diagram of C1 products (CO, methane, formic acid) and C2 products (ethylene, ethane, ethanol, acetic acid) of B-CuO nanotube catalytic material. At a voltage of -0.6 V, the Faraday efficiency of C2 products reached 60%.

[0050] Figure 4 c is the stability test of the B-CuO nanotube catalytic material. It can be seen that after 10 hours of stability test, the current value and C2 selectivity of the B-CuO nanotube catalytic material did not change much, showing excellent stability.

[0051] It was shown that the B-CuO nanotube catalytic material prepared in this example exhibited excellent catalytic activity and C2 product selectivity under 1 mol / L KOH.

[0052] Example 2 (the molar ratio of copper nitrate to boric acid is 1:1)

[0053] A method for preparing a B-doped CuO nanotube catalyst for electrocatalytic CO2 reduction to C2 products, the method comprising the following steps:

[0054] (1) 2 g of polyvinyl pyrrolidone powder was added to a mixed solution of 8 g of ethanol and 8 g of N,N-dimethylformamide, and after stirring evenly, 0.75 g of copper nitrate and 0.25 g of boric acid were added to the above solution (the total amount of metal salt was 1 g, and the molar ratio of copper nitrate to boric acid was 1:1). After stirring for 10 hours, a uniformly mixed ultrafine fiber precursor solution was obtained;

[0055] The precursor solution was then transferred to a syringe and spun using electrospinning technology. The control voltage was 18 kV, the distance from the syringe needle to the receiver was 18 cm, and the solution pushing speed was 0.01 mL / min. After continuous spinning for 24 hours, the precursor mixed nanofiber membrane was obtained.

[0056] (2) 0.2 g of the mixed nanofiber membrane prepared in step (1) was placed in a corundum boat, which was placed in the middle of a tubular furnace. The temperature was raised to 200°C at a heating rate of 2°C / min in an air atmosphere, and the temperature was kept in air for 3 hours for pre-oxidation treatment. The temperature was then raised at a heating rate of 2°C / min to 500°C and kept for 3 hours. After the insulation was completed, the temperature was naturally cooled to room temperature to obtain a B-CuO nanotube catalytic material.

[0057] Example 3 (the molar ratio of copper nitrate to boric acid is 3:1)

[0058] A method for preparing a B-doped CuO nanotube catalyst for electrocatalytic CO2 reduction to C2 products, the method comprising the following steps:

[0059] (1) 2 g of polyvinyl pyrrolidone powder was added to a mixed solution of 8 g of ethanol and 8 g of N,N-dimethylformamide, and after vigorous stirring, 0.9 g of copper nitrate and 0.1 g of boric acid were added to the above solution (the total amount of metal salt was 1 g, and the molar ratio of copper nitrate to boric acid was 3:1). After stirring for 10 hours, a uniformly mixed ultrafine fiber precursor solution was obtained;

[0060] The precursor solution was then transferred to a syringe and spun using electrospinning technology. The control voltage was 18 kV, the distance from the syringe needle to the receiver was 18 cm, and the solution pushing speed was 0.01 mL / min. After continuous spinning for 24 hours, the precursor mixed nanofiber membrane was obtained.

[0061] (2) Take 0.2 g of the mixed nanofiber membrane prepared in step (1) and put it into a corundum boat, place it in the middle position of a tube furnace, raise the temperature to 200°C at a heating rate of 2°C / min in an air atmosphere, and keep it in air for 3 hours for pre-oxidation treatment. Then, raise the temperature at a heating rate of 2°C / min to 500°C and keep it for 3 hours. After the insulation is completed, it naturally cools to room temperature to obtain a B-CuO nanotube catalytic material.

[0062] Example 4 (calcination temperature is 400°C)

[0063] A method for preparing a B-doped CuO nanotube catalyst for electrocatalytic CO2 reduction to C2 products, the method comprising the following steps:

[0064] (1) 2 g of polyvinyl pyrrolidone powder was added to a mixed solution of 8 g of ethanol and 8 g of N,N-dimethylformamide, and after vigorous stirring, 0.86 g of copper nitrate and 0.14 g of boric acid were added to the above solution (the total amount of metal salt was 1 g, and the molar ratio of copper nitrate to boric acid was 2:1). After stirring for 10 hours, a uniformly mixed ultrafine fiber precursor solution was obtained;

[0065] The precursor solution was then transferred to a syringe and spun using electrospinning technology. The control voltage was 18 kV, the distance from the syringe needle to the receiver was 18 cm, and the solution pushing speed was 0.01 mL / min. After continuous spinning for 24 hours, the precursor mixed nanofiber membrane was obtained.

[0066] (2) Take 0.2 g of the mixed nanofiber membrane prepared in step (1) and put it into a corundum boat, place it in the middle position of a tube furnace, raise the temperature to 200°C at a heating rate of 2°C / min in an air atmosphere, and keep it in air for 3 hours for pre-oxidation treatment. Then, raise the temperature at a heating rate of 2°C / min to 400°C and keep it for 3 hours. After the insulation is completed, it naturally cools to room temperature to obtain a B-CuO nanotube catalytic material.

[0067] Example 5 (calcination temperature is 600°C)

[0068] A method for preparing a B-doped CuO nanotube catalyst for electrocatalytic CO2 reduction to C2 products, the method comprising the following steps:

[0069] (1) 2 g of polyvinyl pyrrolidone powder was added to a mixed solution of 8 g of ethanol and 8 g of N,N-dimethylformamide, and the mixture was stirred vigorously. Then, 0.86 g of copper nitrate and 0.14 g of boric acid were weighed and added to the above solution (the total amount of metal salt was 1 g, and the molar ratio of copper nitrate to boric acid was 2:1). After stirring for 10 hours, a uniformly mixed ultrafine fiber precursor solution was obtained.

[0070] The precursor solution was then transferred to a syringe and spun using electrospinning technology. The control voltage was 18 kV, the distance from the syringe needle to the receiver was 18 cm, and the solution pushing speed was 0.01 mL / min. After continuous spinning for 24 hours, the precursor mixed nanofiber membrane was obtained.

[0071] (2) Take 0.2 g of the mixed nanofiber membrane prepared in step (1) and put it into a corundum boat, place it in the middle position of a tube furnace, raise the temperature to 200°C at a heating rate of 2°C / min in an air atmosphere, and keep it in air for 3 hours for pre-oxidation treatment. Then, raise the temperature at a heating rate of 2°C / min to 600°C and keep it for 3 hours. After the insulation is completed, it naturally cools to room temperature to obtain a B-CuO nanotube catalytic material.

[0072] Example 6 (heating rate is 1°C / min)

[0073] A method for preparing a B-doped CuO nanotube catalyst for electrocatalytic CO2 reduction to C2 products, the method comprising the following steps:

[0074] (1) 2 g of polyvinyl pyrrolidone powder was added to a mixed solution of 8 g of ethanol and 8 g of N,N-dimethylformamide, and the mixture was stirred vigorously. Then, 0.86 g of copper nitrate and 0.14 g of boric acid were weighed and added to the above solution (the total amount of metal salt was 1 g, and the molar ratio of copper nitrate to boric acid was 2:1). After stirring for 10 hours, a uniformly mixed ultrafine fiber precursor solution was obtained.

[0075] The precursor solution was then transferred to a syringe and spun using electrospinning technology. The control voltage was 18 kV, the distance from the syringe needle to the receiver was 18 cm, and the solution pushing speed was 0.01 mL / min. After continuous spinning for 24 hours, the precursor mixed nanofiber membrane was obtained.

[0076] (2) Take 0.2 g of the mixed nanofiber membrane prepared in step (1) and put it into a corundum boat, place it in the middle position of a tube furnace, raise the temperature to 200°C at a heating rate of 1°C / min in an air atmosphere, and keep it in air for 3 hours for pre-oxidation treatment. Then, raise the temperature at a heating rate of 1°C / min to 500°C and keep it for 3 hours. After the insulation is completed, it naturally cools to room temperature to obtain a B-CuO nanotube catalytic material.

[0077] The electrocatalytic CO2 reduction performance of the B-CuO nanotube catalytic material prepared in this embodiment is similar to that of embodiment 1.

[0078] Example 7 (heating rate is 5°C / min)

[0079] A method for preparing a B-doped CuO nanotube catalyst for electrocatalytic CO2 reduction to C2 products, the method comprising the following steps:

[0080] (1) 2 g of polyvinyl pyrrolidone powder was added to a mixed solution of 8 g of ethanol and 8 g of N,N-dimethylformamide, and the mixture was stirred vigorously. Then, 0.86 g of copper nitrate and 0.14 g of boric acid were weighed and added to the above solution (the total amount of metal salt was 1 g, and the molar ratio of copper nitrate to boric acid was 2:1). After stirring for 10 hours, a uniformly mixed ultrafine fiber precursor solution was obtained.

[0081] The precursor solution was then transferred to a syringe and spun using electrospinning technology. The control voltage was 18 kV, the distance from the syringe needle to the receiver was 18 cm, and the solution pushing speed was 0.01 mL / min. After continuous spinning for 24 hours, the precursor mixed nanofiber membrane was obtained.

[0082] (2) Take 0.2 g of the mixed nanofiber membrane prepared in step (1) and put it into a corundum boat, place it in the middle position of a tube furnace, raise the temperature to 200°C at a heating rate of 5°C / min in an air atmosphere, and keep it in air for 3 hours for pre-oxidation treatment. Then, raise the temperature at a heating rate of 5°C / min to 500°C and keep it for 3 hours. After the insulation is completed, it naturally cools to room temperature to obtain a B-CuO nanotube catalytic material.

[0083] Example 8 (heating rate is 10°C / min)

[0084] A method for preparing a B-doped CuO nanotube catalyst for electrocatalytic CO2 reduction to C2 products, the method comprising the following steps:

[0085] (1) 2 g of polyvinyl pyrrolidone powder was added to a mixed solution of 8 g of ethanol and 8 g of N,N-dimethylformamide, and the mixture was stirred vigorously. Then, 0.86 g of copper nitrate and 0.14 g of boric acid were weighed and added to the above solution (the total amount of metal salt was 1 g, and the molar ratio of copper nitrate to boric acid was 2:1). After stirring for 10 hours, a uniformly mixed ultrafine fiber precursor solution was obtained.

[0086] The precursor solution was then transferred to a syringe and spun using electrospinning technology. The control voltage was 18 kV, the distance from the syringe needle to the receiver was 18 cm, and the solution pushing speed was 0.01 mL / min. After continuous spinning for 24 hours, the precursor mixed nanofiber membrane was obtained.

[0087] (2) Take 0.2 g of the mixed nanofiber membrane prepared in step (1) and put it into a corundum boat, place it in the middle position of a tube furnace, raise the temperature to 200°C at a heating rate of 10°C / min in an air atmosphere, and keep it in air for 3 hours for pre-oxidation treatment. Then, raise the temperature at a heating rate of 10°C / min to 500°C and keep it for 3 hours. After the insulation is completed, it naturally cools to room temperature to obtain a B-CuO nanotube catalytic material.

[0088] Comparative Example 1

[0089] A method for preparing a B-doped CuO nanotube catalyst for electrocatalytic CO2 reduction to C2 products, the method comprising the following steps:

[0090] (1) Add 2 g of polyvinyl pyrrolidone powder to a mixed solution of 8 g of ethanol and 8 g of N,N-dimethylformamide, stir evenly, weigh 1 g of copper nitrate and add it to the above solution, stir for 10 hours, and obtain a uniformly mixed ultrafine fiber precursor solution;

[0091] The precursor solution was then transferred to a syringe and spun using electrospinning technology. The control voltage was 18 kV, the distance from the syringe needle to the receiver was 18 cm, and the solution pushing speed was 0.01 mL / min. After continuous spinning for 24 hours, the precursor mixed nanofiber membrane was obtained.

[0092] (2) Take 0.2 g of the mixed nanofiber membrane prepared in step (1) and put it into a corundum boat. As for the middle position of the tube furnace, raise the temperature to 200°C at a heating rate of 2°C / min in an air atmosphere and keep it in air for 3 hours for pre-oxidation treatment. Then, raise the temperature at a heating rate of 2°C / min to 500°C and keep it for 3 hours. After the insulation is completed, it naturally cools to room temperature to obtain the CuO nanotube catalytic material.

[0093] Figure 5 The electrocatalytic CO2 reduction performance of the CuO nanotube catalytic material prepared in this comparative example is that the highest Faraday efficiency of C2 is only 25%, and its product is mainly C1, and the Faraday efficiency of C1 product is 41%.

[0094] Comparative Example 2 (the only difference from Example 1 is that the calcination temperature is 300° C.)

[0095] (1) 2 g of polyvinyl pyrrolidone powder was added to a mixed solution of 8 g of ethanol and 8 g of N,N-dimethylformamide, and stirred evenly. Then, 0.86 g of copper nitrate and 0.14 g of boric acid were weighed and added to the above solution (the total amount of metal salt was 1 g, and the molar ratio of copper nitrate to boric acid was 2:1). After stirring for 10 hours, a uniformly mixed ultrafine fiber precursor solution was obtained.

[0096] The precursor solution was then transferred to a syringe and spun using electrospinning technology. The control voltage was 18 kV, the distance from the syringe needle to the receiver was 18 cm, and the solution pushing speed was 0.01 mL / min. After continuous spinning for 24 hours, the precursor mixed nanofiber membrane was obtained.

[0097] (2) Take 0.2 g of the mixed nanofiber membrane prepared in step (1) and put it into a corundum boat. As for the middle position of the tubular furnace, raise the temperature to 200°C at a heating rate of 2°C / min in an air atmosphere and keep it in air for 3 hours for pre-oxidation treatment. Then, raise the temperature at a heating rate of 2°C / min to 300°C and keep it for 3 hours. After the insulation is completed, it naturally cools to room temperature to obtain the B-CuO nanobelt catalytic material.

[0098] Figure 6 a is the microscopic morphology of the B-CuO nanobelt catalytic material prepared in this comparative example. It can be seen from the figure that when the calcination temperature is 300°C, the microscopic morphology of the material is a nanobelt structure. Figure 6 b is the electrocatalytic CO2 reduction performance of B-CuO nanobelt catalytic material, and its product is mainly H2, accompanied by a small amount of C1 product.

[0099] Comparative Example 3 (the only difference from Example 1 is that the calcination temperature is 700°C)

[0100] (1) 2 g of polyvinyl pyrrolidone powder was added to a mixed solution of 8 g of ethanol and 8 g of N,N-dimethylformamide, and stirred evenly. Then, 0.86 g of copper nitrate and 0.14 g of boric acid were weighed and added to the above solution (the total amount of metal salt was 1 g, and the molar ratio of copper nitrate to boric acid was 2:1). After stirring for 10 hours, a uniformly mixed ultrafine fiber precursor solution was obtained.

[0101] The precursor solution was then transferred to a syringe and spun using electrospinning technology. The control voltage was 18 kV, the distance from the syringe needle to the receiver was 18 cm, and the solution pushing speed was 0.01 mL / min. After continuous spinning for 24 hours, the precursor mixed nanofiber membrane was obtained.

[0102] (2) Take 0.2 g of the mixed nanofiber membrane prepared in step (1) and put it into a corundum boat. As for the middle position of the tube furnace, raise the temperature to 200°C at a heating rate of 2°C / min in an air atmosphere and keep it in air for 3 hours for pre-oxidation treatment. Then, raise the temperature at a heating rate of 2°C / min to 700°C and keep it for 3 hours. After the insulation is completed, it naturally cools to room temperature to obtain the B-CuO nanofiber catalytic material.

[0103] Figure 7 a is the microscopic morphology of the B-CuO nanofiber catalytic material prepared in this comparative example. It can be seen from the figure that when the calcination temperature is 700°C, the microscopic morphology of the material is a porous nanofiber structure. Figure 7 b is the electrocatalytic CO2 reduction performance of the B-CuO nanofiber catalytic material. The Faradaic efficiency of the C1 product in its catalytic product is 29%, and the Faradaic efficiency of the C2 product is 20%.

[0104] Although the present invention has been disclosed above in terms of preferred embodiments, this is not intended to limit the present invention. Anyone familiar with this technology may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for electrocatalytic reduction of CO2 to produce C2 products, characterized in that: The method uses B-doped CuO nanotube catalytic material as a catalyst; The preparation method of the B-doped CuO nanotube catalytic material comprises the following steps: (1) Preparation of hybrid nanofiber membrane A copper source and a boron source are added to a fiber precursor solution, magnetically stirred, and then electrospinned to obtain a mixed nanofiber membrane containing copper and boron; the molar ratio of the copper source to the boron source is 2:1; (2) Preparation of B-doped CuO nanotube catalytic materials The mixed nanofiber membrane prepared in step (1) is pre-oxidized and then calcined at 400-600°C in an air atmosphere for 1-3 hours. After the heat preservation is completed, the mixture is naturally cooled to room temperature to obtain the B-doped CuO nanotube catalytic material B-CuO.

2. The method according to claim 1, characterized in that In step (1), the boron source is one or both of boric acid and boron trioxide; the copper source is one or more of copper nitrate, copper chloride, and copper acetate.

3. The method according to claim 1, wherein In step (1), the fiber precursor solution is a mixed solution of one or more of polyvinyl pyrrolidone, polyacrylonitrile, polyvinyl alcohol, and ethanol and / or N,N-dimethylformamide.

4. The method according to claim 1, wherein In step (1), the total mass of the copper source and the boron source is 20-60 wt% of the fiber precursor solution.

5. The method according to claim 1, wherein In step (2), the temperature of the pre-oxidation treatment of the hybrid nanofiber membrane is 180-250°C, the heating rate is 1-10°C / min, and the holding time is 1-3 hours.

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