A zinc hollow fiber electrode, its preparation method and its application

Abstract

This invention provides a zinc hollow fiber electrode, its preparation method, and its application. The preparation method includes: S1, ball milling a zinc source, an organic solvent, and a binder in a specific ratio at room temperature to obtain a uniform slurry, and then degassing the slurry; S2, extruding the degassed slurry through a core liquid and a spinning head to form initial fibers, which then undergo phase transformation to obtain a hollow fiber soft body; S3, washing and shaping the hollow fiber soft body to obtain a hollow fiber preform; S4, calcining and oxidizing the hollow fiber preform in an oxidizing gas atmosphere to obtain an oxide precursor; S5, obtaining a zinc hollow fiber electrode through in-situ electrochemical reduction. The preparation method of this invention is simple and low-cost. The obtained oxide precursor is reduced in situ to obtain a zinc hollow fiber electrode. When applied to CO2 electrocatalytic reduction, it exhibits good electrocatalytic activity, good CO and syngas selectivity, high current density, and high stability.

Description

Technical Field

[0001] This invention belongs to the field of carbon dioxide electrochemical reduction and conversion technology, and in particular relates to a zinc hollow fiber electrode, its preparation method and its application. Background Technology

[0002] With the accelerating pace of global industrialization, excessive emissions of carbon dioxide (CO2) have triggered a severe greenhouse effect, posing a significant threat to the ecological environment and human health. Therefore, the efficient utilization and conversion of CO2 has become a hot topic in current scientific research. Electrocatalytic reduction of CO2 to produce high-value-added chemicals not only converts renewable electrical energy into easily stored and transportable chemical energy, but also offers significant environmental and energy benefits, demonstrating broad application prospects.

[0003] In electrocatalytic CO2 reduction technology, the performance of electrode materials plays a crucial role. Zinc (Zn), as a cost-effective alternative to precious metal silver catalysts, has attracted considerable attention and become increasingly attractive due to its higher abundance on Earth, tunable structural morphology, and selectivity for CO in electrocatalytic CO2 production. However, zinc-based materials still face several unresolved issues. Their limited CO production capacity restricts their potential for large-scale industrial applications, thus the selectivity, catalytic activity, and state stability of zinc-based catalysts need further improvement. Currently, gas diffusion electrodes are one of the commonly used electrode types. However, they have many limitations, such as the need for a large amount of binder during preparation, which not only increases the electrode manufacturing cost but also leads to poor catalyst stability, severely impacting their potential for large-scale applications and limiting the further development of electrocatalytic CO2 reduction technology.

[0004] In contrast, hollow fiber electrodes, with their unique porous structure, possess a large specific surface area and excellent mass transfer performance, exhibiting unique advantages. The development of innovative electrodes such as hollow fiber permeable electrodes (HPEs) has brought new breakthroughs to electrocatalytic CO2 reduction technology. These electrodes can significantly enhance the mass transfer and reaction kinetics of electrochemical reactions at the gas-liquid-solid three-phase interface, effectively overcoming the problem of slow gaseous reactant supply on traditional electrodes. The unique hollow fiber structure facilitates the permeation of gaseous reactants (such as CO2) through the porous walls, ensuring an unlimited supply and direct contact with the active sites on the catalyst surface and the electrolyte, thereby significantly improving the overall efficiency of the reaction and providing strong support for achieving efficient CO2 conversion.

[0005] However, despite the numerous advantages of hollow fiber electrodes, the preparation of zinc hollow fiber electrodes faces significant challenges. Zinc is highly reactive, with its activity sequence preceding that of hydrogen, making it impossible to prepare via thermal reduction in a hydrogen atmosphere or wet chemical reduction methods such as sodium borohydride. Currently, there is no mature and efficient method for preparing zinc hollow fiber electrodes. In particular, ensuring electrode stability and catalytic performance remains a significant challenge, which to some extent restricts the widespread application of zinc hollow fiber electrodes in the electrocatalytic CO2 reduction field. Therefore, an improved technical solution is needed to address the shortcomings of the existing technologies. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a zinc hollow fiber electrode, a preparation method thereof, and its application, to solve the problem that the prior art cannot efficiently prepare zinc hollow fiber electrodes, as well as the problem that the zinc hollow fiber electrode has insufficient stability and catalytic performance in electrocatalytic CO2 reduction.

[0007] To achieve the above and other related objectives, the present invention provides a method for preparing a zinc hollow fiber electrode, the method comprising the following steps:

[0008] S1. At room temperature, the zinc source, organic solvent and binder are ball-milled in a certain proportion to make them uniformly mixed to obtain a uniform slurry. Then the slurry is placed in a vacuum drying oven for degassing.

[0009] S2. The degassed slurry is extruded through the core liquid and the spinning head at a certain flow rate to form initial fibers. The initial fibers are then passed through an air bath and enter the coagulation liquid to undergo phase transformation, resulting in hollow fiber soft body.

[0010] S3. After the hollow fiber soft body is washed and shaped, a hollow fiber preform is obtained.

[0011] S4. The hollow fiber preform is placed in an oxidizing gas atmosphere and heated to a certain temperature at a certain heating rate to calcine and oxidize, thereby obtaining an oxide precursor.

[0012] S5. The oxide precursor is subjected to in-situ electrochemical reduction to obtain a zinc hollow fiber electrode.

[0013] Preferably, the zinc source in step S1 includes one or a combination of zinc powder and zinc oxide powder, the organic solvent includes one or a combination of N-methyl-2-pyrrolidone and N,N-dimethylformamide, and the binder includes one or a combination of polyethyleneimine and polyethersulfone.

[0014] Preferably, in the slurry of step S1, the zinc source accounts for 40 wt% to 70 wt% by mass, the organic solvent accounts for 20 wt% to 50 wt% by mass, and the binder accounts for 5 wt% to 15 wt% by mass.

[0015] Preferably, the particle size of the zinc source particles in step S1 is 50 nm to 10 μm.

[0016] Preferably, the zinc source particles in step S1 are one or more of the following shapes: spherical, flake-shaped, granular, and irregular.

[0017] Preferably, the ball milling time in step S1 is 12h to 48h.

[0018] Preferably, the degassing time in step S1 is 4h to 24h.

[0019] Preferably, the slurry in step S2 is extruded through the spinning head at a flow rate of 5 to 25 mL / min.

[0020] Preferably, the size of the spinning head in step S2 is one or a combination of Φ1.0×0.3mm, Φ1.5×0.3mm, Φ1.5×0.5mm, and Φ2.0×1.0mm.

[0021] Preferably, the flow rate of the core fluid in step S2 is 5 to 25 mL / min.

[0022] Preferably, the air distance between the spinning head and the surface of the coagulated liquid in step S2 is 0.1 to 3 cm.

[0023] Preferably, the oxidizing gas in step S4 is air or oxygen.

[0024] Preferably, the flow rate of the oxidizing gas in step S4 is 50–400 mL / min.

[0025] Preferably, the heating rate in step S4 is 0.5 to 8 °C / min.

[0026] Preferably, the calcination oxidation temperature in step S4 is 500–1200°C.

[0027] Preferably, the calcination oxidation time in step S4 is 1 to 8 hours.

[0028] Preferably, the in-situ electrochemical reduction in step S5 specifically includes the following steps: first, the oxide precursor is reduced at a constant cathodic potential in an electrolyte, and then reduced at a constant current.

[0029] Preferably, the in-situ electrochemical reduction in step S5 needs to be carried out in a gaseous atmosphere, which includes one or a combination of carbon dioxide, nitrogen, and argon.

[0030] Preferably, the electrolyte in step S5 is one or a combination of K2CO3, KHCO3, K2SO4, KOH, KCl, Na2CO3, NaHCO3, Na2SO4, NaOH, and NaCl.

[0031] Preferably, the concentration of the electrolyte in step S5 is 0.1–3 M.

[0032] Preferably, the potential range for the constant potential reduction in step S5 is -1.2 to -10 V vs. Ag / AgCl electrode, and the constant potential reduction time is 5 min to 60 min; the current density for the constant current reduction is -0.1 to -1.0 A / cm². 2 The constant current restoration time is 5 min to 60 min.

[0033] The present invention also provides a zinc hollow fiber electrode prepared by the above-described method for preparing a zinc hollow fiber electrode. The zinc hollow fiber electrode is a porous hollow fiber tubular structure, including an inner surface and an outer surface. The wall thickness of the zinc hollow fiber electrode is 0.1 mm to 1 mm, and the average pore size of the inner and outer surfaces is 0.5 μm to 10 μm.

[0034] This invention also provides an application of a zinc hollow fiber electrode, which is used for the electrocatalytic conversion of CO2 to produce CO and syngas. Specifically, it includes the following steps: passing CO2 into the zinc hollow fiber electrode, placing the zinc hollow fiber electrode in an electrolyte, applying a constant potential or a constant current to electrochemically reduce CO2, and electrocatalytically converting CO2 into CO and syngas with an adjustable ratio of CO to H2.

[0035] Preferably, the electrolyte comprises a catholyte and an anolyte, wherein the catholyte is one or a combination of K2CO3, KHCO3, K2SO4, KCl, Na2CO3, NaHCO3, Na2SO4, and NaCl, and the anolyte is one or a combination of K2CO3, KHCO3, K2SO4, KOH, Na2CO3, NaHCO3, Na2SO4, and NaOH.

[0036] Preferably, the concentrations of both the catholyte and the anolyte are 0.1–5 M.

[0037] Preferably, the potential range applied during the electrochemical reduction of CO2 is -0.5 to -10 V vs. RHE.

[0038] Preferably, the applied current density during the electrochemical reduction of CO2 is in the range of -0.01 to -5 A / cm. 2 .

[0039] As described above, the zinc hollow fiber electrode, its preparation method, and its application of the present invention have the following beneficial effects:

[0040] The preparation method of this invention is simple and low-cost. A simple phase inversion method can efficiently prepare hollow fiber preforms. After calcination in an oxidizing atmosphere, an oxide precursor is obtained. The oxide precursor is further subjected to in-situ electrochemical reduction to obtain a zinc hollow fiber electrode. The zinc hollow fiber electrode prepared by this invention can be applied to the electrocatalytic reduction of CO2, especially to the reaction of CO2 electrocatalytic conversion to CO and syngas. The Faraday current efficiency of CO can reach up to 93.8% at room temperature and pressure, and the ratio of CO to H2 in the generated syngas is adjustable. This zinc hollow fiber electrode has good electrocatalytic activity, good CO and syngas selectivity, high current density and high stability, and has extremely high application prospects. Attached Figure Description

[0041] Figure 1 The image shown is a SEM image of the cross-section of the oxide precursor obtained in Example 2 of this invention.

[0042] Figure 2 The image shown is a SEM image of the cross-section of the zinc hollow fiber electrode obtained in Example 2 of this invention. Detailed Implementation

[0043] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0044] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the respective manufacturers.

[0045] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0046] This invention provides a method for preparing a zinc hollow fiber electrode, the method comprising the following steps:

[0047] S1. At room temperature, the zinc source, organic solvent and binder are ball-milled in a certain proportion to make them uniformly mixed to obtain a uniform slurry. Then the slurry is placed in a vacuum drying oven for degassing.

[0048] S2. The degassed slurry is extruded through the core liquid and the spinning head at a certain flow rate to form initial fibers. The initial fibers are then passed through an air bath and enter the coagulation liquid to undergo phase transformation, resulting in hollow fiber soft body.

[0049] S3. After the hollow fiber soft body is washed and shaped, a hollow fiber preform is obtained.

[0050] S4. The hollow fiber preform is placed in an oxidizing gas atmosphere and heated to a certain temperature at a certain heating rate to calcine and oxidize, thereby obtaining an oxide precursor.

[0051] S5. The oxide precursor is subjected to in-situ electrochemical reduction to obtain a zinc hollow fiber electrode.

[0052] First, in step S1, the zinc source, organic solvent and binder are ball-milled at a certain ratio at room temperature to obtain a uniform slurry. Then, the slurry is placed in a vacuum drying oven for degassing.

[0053] As an example, in step S1, the zinc source includes one or a combination of zinc powder and zinc oxide powder, the organic solvent includes one or a combination of N-methyl-2-pyrrolidone and N,N-dimethylformamide, and the binder includes one or a combination of polyethyleneimine and polyethersulfone.

[0054] As an example, in the slurry of step S1, the zinc source accounts for 40 wt% to 70 wt% by mass percentage, the organic solvent accounts for 20 wt% to 50 wt% by mass percentage, and the binder accounts for 5 wt% to 15 wt% by mass percentage.

[0055] Specifically, by mass percentage, the zinc source accounts for 40wt% to 70wt%, such as 40wt%, 50wt%, 60wt%, 70wt%, etc.; the organic solvent accounts for 20wt% to 50wt%, such as 20wt%, 30wt%, 40wt%, 50wt%, etc.; and the binder accounts for 5wt% to 15wt%, such as 5wt%, 8wt%, 10wt%, 12wt%, 15wt%, etc.

[0056] As an example, the particle size of the zinc source particles in step S1 is 50 nm to 10 μm.

[0057] Specifically, the particle size of the zinc source particles can include any value within the range of 50nm, 100nm, 500nm, 1μm, 5μm, 10μm, etc.

[0058] As an example, the shape of the zinc source particles in step S1 is one or more of the following: spherical, flake-shaped, granular, and irregular shapes.

[0059] Preferably, the zinc source is spherical zinc powder with a particle size of 50 nm to 10 μm.

[0060] As an example, the ball milling time in step S1 is 12 to 48 hours.

[0061] Specifically, the ball milling time can be any value within the range of 12h, 24h, 36h, 48h, etc. Preferably, the ball milling time is 18 to 24h, such as 18h, 19h, 20h, 21h, 22h, 23h, 24h, etc.

[0062] As an example, the degassing time in step S1 is 4 to 24 hours.

[0063] Specifically, the degassing time can be any value within the range of 4h, 8h, 12h, 16h, 20h, 24h, etc.; preferably, the degassing time is 10 to 15h, such as 10h, 11h, 12h, 13h, 14h, 15h, etc.

[0064] Then, in step S2, the degassed slurry is extruded through the core liquid and the spinning head at a certain flow rate to form initial fibers. The initial fibers then enter the coagulation liquid after passing through an air bath to undergo phase transformation, resulting in hollow fiber soft bodies.

[0065] As an example, in step S2, the slurry is extruded through the spinning head at a flow rate of 5–25 mL / min.

[0066] Specifically, the flow rate of the slurry through the spinning head can be any value within the range of 5 mL / min, 10 mL / min, 15 mL / min, 20 mL / min, 25 mL / min, etc.

[0067] As an example, the size of the spinning head in step S2 is one or a combination of Φ1.0×0.3mm, Φ1.5×0.3mm, Φ1.5×0.5mm, and Φ2.0×1.0mm.

[0068] As an example, the flow rate of the core fluid in step S2 is 5–25 mL / min.

[0069] Specifically, the flow rate of the core fluid can be any value within the range of 5 mL / min, 10 mL / min, 15 mL / min, 20 mL / min, 25 mL / min, etc.

[0070] As an example, in step S2, the air distance between the spinning head and the surface of the coagulating liquid is 0.1 to 3 cm.

[0071] Specifically, the air distance between the spinning head and the surface of the coagulating liquid can be any value within the range of 0.1cm, 0.5cm, 1cm, 2cm, 3cm, etc.; preferably, the air distance between the spinning head and the surface of the coagulating liquid is 1cm.

[0072] Then, step S3 is performed, and after the hollow fiber soft body is washed and shaped, a hollow fiber preform is obtained.

[0073] Specifically, the hollow fiber soft material is washed with plenty of tap water to remove the organic solvents. The shaping process involves straightening and fixing the hollow fiber soft material, and then air-drying it naturally in the air.

[0074] Then, step S4 is performed, in which the hollow fiber preform is placed in an oxidizing gas atmosphere and heated to a certain temperature at a certain heating rate to obtain an oxide precursor.

[0075] As an example, the oxidizing gas in step S4 is air or oxygen.

[0076] As an example, the flow rate of the oxidizing gas in step S4 is 50–400 mL / min.

[0077] Specifically, the flow rate of the oxidizing gas can include any value within the range of 50 mL / min, 100 mL / min, 150 mL / min, 200 mL / min, 250 mL / min, 300 mL / min, 400 mL / min, etc.; preferably, the flow rate of the oxidizing gas is 100 to 200 mL / min, such as 100 mL / min, 120 mL / min, 140 mL / min, 160 mL / min, 180 mL / min, 200 mL / min, etc.

[0078] As an example, the heating rate in step S4 is 0.5–8 °C / min.

[0079] Specifically, the heating rate can be any value within the range of 0.5℃ / min, 1℃ / min, 2℃ / min, 4℃ / min, 6℃ / min, 8℃ / min, etc.

[0080] As an example, the calcination and oxidation temperature in step S4 is 500–1200°C.

[0081] Specifically, the calcination oxidation temperature can include any value within the range of 500℃, 800℃, 1000℃, 1200℃, etc.; preferably, the calcination oxidation temperature is 500~800℃, such as 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, etc.

[0082] As an example, the calcination oxidation time in step S4 is 1 to 8 hours.

[0083] Specifically, the calcination and oxidation time can be any value within the range of 1h, 2h, 4h, 6h, 8h, etc.; preferably, the calcination and oxidation time is 2 to 6h, such as 2h, 3h, 4h, 5h, 6h, etc.

[0084] Finally, step S5 is performed to reduce the oxide precursor in situ using electrochemical methods to obtain a zinc hollow fiber electrode.

[0085] As an example, the in-situ electrochemical reduction in step S5 specifically includes the following steps: first, the oxide precursor is reduced at a cathodic constant potential in the electrolyte, and then reduced at a constant current.

[0086] Specifically, the oxide precursor is first subjected to cathodic constant potential reduction in an electrolyte to slowly reduce the surface oxide species to metal and improve its electronic conductivity; then constant current reduction is performed to rapidly reduce the bulk oxide species to metal, finally obtaining the zinc hollow fiber electrode.

[0087] As an example, the in-situ electrochemical reduction in step S5 needs to be carried out in a gaseous atmosphere, which includes one or a combination of carbon dioxide, nitrogen, and argon.

[0088] Specifically, during the in-situ electrochemical reduction reaction, the gas can be directly introduced into the tubular oxide precursor or directly into the electrolyte. The flow rate of the gas atmosphere is 1–100 mL / min, such as 1 mL / min, 5 mL / min, 10 mL / min, 20 mL / min, 50 mL / min, 100 mL / min, etc.; preferably, the flow rate of the gas atmosphere is 5–50 mL / min, such as 5 mL / min, 10 mL / min, 20 mL / min, 50 mL / min, etc.

[0089] As an example, the electrolyte in step S5 is one or a combination of K2CO3, KHCO3, K2SO4, KOH, KCl, Na2CO3, NaHCO3, Na2SO4, NaOH, and NaCl.

[0090] As an example, the concentration of the electrolyte in step S5 is 0.1–3 M.

[0091] Specifically, the concentration of the electrolyte can be any value within the range of 0.1M, 0.5M, 1M, 2M, 3M, etc.; preferably, the electrolyte is 3.0M KHCO3.

[0092] As an example, in step S5, the potential range for constant-potential reduction is -1.2 to -10 V vs. Ag / AgCl electrode, and the constant-potential reduction time is 5 to 60 min; the current density for constant-current reduction is -0.1 to -1.0 A / cm². 2 The constant current restoration time is 5 to 60 minutes.

[0093] Specifically, the potential range for constant potential reduction can include any value within the range of -1.2V vs. Ag / AgCl electrode, -1.4V vs. Ag / AgCl electrode, -2.0V vs. Ag / AgCl electrode, -4.0V vs. Ag / AgCl electrode, -6.0V vs. Ag / AgCl electrode, -8.0V vs. Ag / AgCl electrode, and -10.0V vs. Ag / AgCl electrode. The time for constant potential reduction can include any value within the range of 5min, 10min, 20min, 40min, and 60min.

[0094] The current density for constant current reduction can include -0.1 A / cm². 2 -0.2A / cm 2 -0.4A / cm 2 -0.6A / cm2 -1.0A / cm 2 The constant current restoration time can be any value within any range, including 5 min, 10 min, 20 min, 40 min, 60 min, etc.

[0095] Preferably, the potential for constant-potential reduction is -1.8V vs. the Ag / AgCl electrode, and the constant-potential reduction time is 10 min; the current density for constant-current reduction is -0.2 A / cm². 2 The constant current restoration time is 10 minutes.

[0096] The present invention also provides a zinc hollow fiber electrode prepared by the above-described method for preparing zinc hollow fiber electrodes. The zinc hollow fiber electrode is a porous hollow fiber tubular structure, including an inner surface and an outer surface. The wall thickness of the zinc hollow fiber electrode is 0.1 mm to 1 mm, and the average pore size of the inner and outer surfaces is 0.5 μm to 10 μm.

[0097] Specifically, the wall thickness of the zinc hollow fiber electrode can range from 0.1 mm, 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, to 1 mm. The average pore size of the inner and outer surfaces of the tube can range from 0.5 μm, 0.6 μm, 1 μm, 3 μm, 5 μm, 7 μm, 9 μm, to 10 μm.

[0098] This invention also provides an application of a zinc hollow fiber electrode, which is used for the electrocatalytic conversion of CO2. Specifically, it includes the following steps: passing CO2 into the zinc hollow fiber electrode, placing the zinc hollow fiber electrode in an electrolyte, applying a constant potential or a constant current to electrochemically reduce CO2, and electrocatalytically converting CO2 into CO, and syngas with an adjustable ratio of CO to H2.

[0099] Specifically, the bottom of the zinc hollow fiber electrode is sealed, and CO2 is introduced from the top. The CO2 escapes from the porous wall of the zinc hollow fiber electrode, and the CO2 feed gas comes into contact with the electrolyte, enhancing the gas-liquid-solid three-phase reaction interface and simultaneously strengthening the mass transfer process between reactants and products. The total flow rate of CO2 introduced is 1–100 mL / min, and the temperature for CO2 electrocatalytic conversion is 10–60 °C.

[0100] As an example, the electrolyte includes a cathode solution and an anolyte, wherein the cathode solution is one or a combination of K2CO3, KHCO3, K2SO4, KCl, Na2CO3, NaHCO3, Na2SO4, and NaCl, and the anolyte includes one or a combination of K2CO3, KHCO3, K2SO4, KOH, Na2CO3, NaHCO3, Na2SO4, and NaOH.

[0101] As an example, the concentrations of both the catholyte and anolyte are 0.1–5 M.

[0102] Specifically, the concentrations of the catholyte and anolyte can be any value within the range of 0.1M, 0.5M, 1M, 2M, 3M, 4M, 5M, etc.; preferably, the catholyte is 3.0M KCl and the anolyte is 3.0M KOH.

[0103] As an example, the potential range applied during the electrochemical reduction of CO2 is -0.5 to -10 V vs. RHE.

[0104] Specifically, the potential applied during the electrochemical reduction of CO2 can be any value in the range of -0.5V vs. RHE, -1.0V vs. RHE, -2.0V vs. RHE, -5.0V vs. RHE, -8.0V vs. RHE, -10.0V vs. RHE, etc.; preferably, the applied potential is -0.8 to -1.4V vs. RHE, such as -0.8V vs. RHE, -0.9V vs. RHE, -1.0V vs. RHE, -1.2V vs. RHE, -1.4V vs. RHE, etc.

[0105] As an example, the applied current density range during the electrochemical reduction of CO2 is -0.1 to -5 A / cm. 2 .

[0106] Specifically, the applied current density during the electrochemical reduction of CO2 can include -0.1 A / cm². 2 -1A / cm 2 -2A / cm 2 -3A / cm 2 -4A / cm 2 -5A / cm 2 The applied current density can be any value within a certain range; preferably, it is -0.05 to -1.2 A / cm². 2 For example, -0.05A / cm 2 -0.2A / cm 2 -0.4A / cm 2 -0.8A / cm 2 -1.2A / cm 2 wait.

[0107] To better understand the zinc hollow fiber electrode, its preparation method, and its application in this invention, specific embodiments are described below. It should be noted that these embodiments are merely descriptive and do not limit the invention in any way.

[0108] Example 1

[0109] This embodiment provides a method for preparing a zinc hollow fiber electrode, which includes the following steps:

[0110] S1. At room temperature, spherical zinc powder with a particle size of 1 μm, N-methyl-2-pyrrolidone and polyethyleneimine are mixed in proportions of 50 wt%, 40 wt%, and 10 wt%, respectively, and ball-milled at a speed of 300 r / min for 24 h to obtain a uniform slurry. The slurry is then placed in a vacuum drying oven for degassing for 5 h.

[0111] S2. The degassed slurry is extruded through the core liquid and a Φ1.5×0.3mm spinning head at a flow rate of 5mL / min to form initial fibers. The initial fibers are then passed through an air bath and enter the coagulation liquid to undergo phase transformation, resulting in hollow fiber soft bodies. The core liquid is ultrapure water with a flow rate of 5mL / min, the coagulation liquid is tap water, and the air distance between the spinning head and the surface of the coagulation liquid is 1cm.

[0112] S3. Wash the hollow fiber soft body with a large amount of tap water to remove organic solvents, and after shaping, obtain hollow fiber preforms.

[0113] S4. The hollow fiber preform is placed in an air atmosphere with a flow rate of 100 mL / min and heated to 600℃ at a heating rate of 5℃ / min for calcination and oxidation for 2 hours to remove the polyethyleneimine in the hollow fiber preform, while causing the zinc particles to sinter and oxidize, thus obtaining the oxide precursor.

[0114] S5. A carbon dioxide gas atmosphere is introduced into the electrolyte at a flow rate of 100 mL / min. The oxide precursor undergoes an electrochemical reduction reaction in a 3 M KHCO3 electrolyte. First, the reduction is carried out at a constant potential of -1.8 V vs. Ag / AgCl for 10 min, and then at -0.2 A / cm. 2 A constant current reduction was performed for 10 minutes to obtain a zinc hollow fiber electrode.

[0115] This embodiment also provides a zinc hollow fiber electrode, which is prepared by the zinc hollow fiber electrode preparation method of this embodiment, and the zinc hollow fiber electrode has a porous hollow fiber tubular structure.

[0116] Example 2

[0117] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Embodiment 1 is that the electrolyte in step S5 is a 3M KCl electrolyte. The other steps and methods are the same as those in Embodiment 1 and will not be repeated here.

[0118] This embodiment also provides a zinc hollow fiber electrode, which is prepared using the zinc hollow fiber electrode preparation method of this embodiment.

[0119] See Figure 1 The images show SEM images of the oxide precursor obtained in this embodiment. The left image is a magnified view of the outer surface at 10,000 times, and the right image is a magnified view of the cross-section at 200 times. As can be seen from the images, the surface of the oxide precursor has nano-peaks and uniform wall thickness.

[0120] See Figure 2 The image shows a cross-section of the zinc hollow fiber electrode prepared in this embodiment. The left image is magnified 10,000 times and the right image is magnified 200 times. As can be seen from the image, the cross-section of the zinc hollow fiber electrode formed after the oxide is converted into metallic zinc is roughened and the wall thickness is reduced.

[0121] Example 3

[0122] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Embodiment 1 is that the electrolyte in step S5 is a 3M NaCl electrolyte. The other steps and methods are the same as those in Embodiment 1 and will not be repeated here.

[0123] This embodiment also provides a zinc hollow fiber electrode, which is prepared using the zinc hollow fiber electrode preparation method of this embodiment.

[0124] Example 4

[0125] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Embodiment 1 is that the electrolyte in step S5 is a 0.5M KHCO3 electrolyte. The other steps and methods are the same as those in Embodiment 1 and will not be repeated here.

[0126] This embodiment also provides a zinc hollow fiber electrode, which is prepared by the zinc hollow fiber electrode preparation method of this embodiment, and the zinc hollow fiber electrode has a porous hollow fiber tubular structure.

[0127] Example 5

[0128] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Embodiment 1 is that in step S5, the electrode is first reduced at a constant potential of -1.2V vs. Ag / AgCl for 10 minutes, and then reduced at -0.2A / cm. 2 The constant current restoration was performed for 10 minutes. Other steps and methods were the same as in Example 1, and will not be repeated here.

[0129] This embodiment also provides a zinc hollow fiber electrode, which is prepared by the zinc hollow fiber electrode preparation method of this embodiment, and the zinc hollow fiber electrode has a porous hollow fiber tubular structure.

[0130] Example 6

[0131] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Embodiment 1 is that in step S5, the electrode is first reduced at a constant potential of -3V vs. Ag / AgCl for 10 minutes, and then at -0.2A / cm. 2 The constant current restoration was performed for 10 minutes. Other steps and methods were the same as in Example 1, and will not be repeated here.

[0132] This embodiment also provides a zinc hollow fiber electrode, which is prepared by the zinc hollow fiber electrode preparation method of this embodiment, and the zinc hollow fiber electrode has a porous hollow fiber tubular structure.

[0133] Example 7

[0134] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Embodiment 1 is that in step S5, the electrode is first reduced at a constant potential of -1.8V vs. Ag / AgCl for 30 minutes, and then reduced at -0.2A / cm. 2 The constant current restoration was performed for 10 minutes. Other steps and methods were the same as in Example 1, and will not be repeated here.

[0135] This embodiment also provides a zinc hollow fiber electrode, which is prepared by the zinc hollow fiber electrode preparation method of this embodiment, and the zinc hollow fiber electrode has a porous hollow fiber tubular structure.

[0136] Example 8

[0137] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Embodiment 1 is that in step S5, the electrode is first reduced at a constant potential of -1.8V vs. Ag / AgCl for 10 minutes, and then reduced at -0.1A / cm. 2 The constant current restoration was performed for 10 minutes. Other steps and methods were the same as in Example 1, and will not be repeated here.

[0138] This embodiment also provides a zinc hollow fiber electrode, which is prepared by the zinc hollow fiber electrode preparation method of this embodiment, and the zinc hollow fiber electrode has a porous hollow fiber tubular structure.

[0139] Example 9

[0140] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Embodiment 1 is that in step S5, the electrode is first reduced at a constant potential of -1.8V vs. Ag / AgCl for 10 minutes, and then reduced at -0.5A / cm. 2 The constant current restoration was performed for 10 minutes. Other steps and methods were the same as in Example 1, and will not be repeated here.

[0141] This embodiment also provides a zinc hollow fiber electrode, which is prepared by the zinc hollow fiber electrode preparation method of this embodiment, and the zinc hollow fiber electrode has a porous hollow fiber tubular structure.

[0142] Example 10

[0143] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Embodiment 1 is that in step S5, the electrode is first reduced at a constant potential of -1.8V vs. Ag / AgCl for 10 minutes, and then reduced at -0.2A / cm. 2 The constant current restoration was performed for 30 minutes. Other steps and methods were the same as in Example 1, and will not be repeated here.

[0144] This embodiment also provides a zinc hollow fiber electrode, which is prepared by the zinc hollow fiber electrode preparation method of this embodiment, and the zinc hollow fiber electrode has a porous hollow fiber tubular structure.

[0145] Example 11

[0146] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Embodiment 1 is that the gas atmosphere in step S5 is nitrogen. The other steps and methods are the same as those in Embodiment 1 and will not be repeated here.

[0147] This embodiment also provides a zinc hollow fiber electrode, which is prepared by the zinc hollow fiber electrode preparation method of this embodiment, and the zinc hollow fiber electrode has a porous hollow fiber tubular structure.

[0148] Example 12

[0149] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Embodiment 1 is that the gas atmosphere in step S5 is argon. The other steps and methods are the same as those in Embodiment 1 and will not be repeated here.

[0150] This embodiment also provides a zinc hollow fiber electrode, which is prepared by the zinc hollow fiber electrode preparation method of this embodiment, and the zinc hollow fiber electrode has a porous hollow fiber tubular structure.

[0151] Example 13

[0152] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Example 1 is that in step S1, spherical zinc powder, N-methyl-2-pyrrolidone and polyethyleneimine are mixed in proportions of 50wt%, 45wt%, and 5wt%, respectively. Other steps and methods are the same as in Example 1 and will not be repeated here.

[0153] This embodiment also provides a zinc hollow fiber electrode, which is prepared by the zinc hollow fiber electrode preparation method of this embodiment, and the zinc hollow fiber electrode has a porous hollow fiber tubular structure.

[0154] Example 14

[0155] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Example 1 is that in step S1, spherical zinc powder, N-methyl-2-pyrrolidone and polyethyleneimine are mixed in proportions of 50wt%, 35wt%, and 15wt%, respectively. Other steps and methods are the same as in Example 1 and will not be repeated here.

[0156] This embodiment also provides a zinc hollow fiber electrode, which is prepared by the zinc hollow fiber electrode preparation method of this embodiment, and the zinc hollow fiber electrode has a porous hollow fiber tubular structure.

[0157] Example 15

[0158] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Example 1 is that in step S1, spherical zinc powder, N-methyl-2-pyrrolidone and polyethyleneimine are mixed in proportions of 65wt%, 20wt%, and 15wt%, respectively. Other steps and methods are the same as in Example 1 and will not be repeated here.

[0159] This embodiment also provides a zinc hollow fiber electrode, which is prepared by the zinc hollow fiber electrode preparation method of this embodiment, and the zinc hollow fiber electrode has a porous hollow fiber tubular structure.

[0160] Example 16

[0161] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Example 1 is that in step S1, spherical zinc powder, N-methyl-2-pyrrolidone and polyethyleneimine are mixed in proportions of 70wt%, 20wt%, and 10wt%, respectively. Other steps and methods are the same as in Example 1 and will not be repeated here.

[0162] This embodiment also provides a zinc hollow fiber electrode, which is prepared by the zinc hollow fiber electrode preparation method of this embodiment, and the zinc hollow fiber electrode has a porous hollow fiber tubular structure.

[0163] Example 17

[0164] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Embodiment 1 is that spherical zinc oxide powder with a particle size of 1 μm is used in step S1, and the hollow fiber preform in S4 is calcined and oxidized at 1200℃ for 2 hours. Other steps and methods are the same as those in Embodiment 1 and will not be repeated here.

[0165] This embodiment also provides a zinc hollow fiber electrode, which is prepared by the zinc hollow fiber electrode preparation method of this embodiment, and the zinc hollow fiber electrode has a porous hollow fiber tubular structure.

[0166] Example 18

[0167] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Example 1 is that the organic solvent used in step S1 is N,N-dimethylformamide. Other steps and methods are the same as in Example 1 and will not be repeated here.

[0168] This embodiment also provides a zinc hollow fiber electrode, which is prepared by the zinc hollow fiber electrode preparation method of this embodiment, and the zinc hollow fiber electrode has a porous hollow fiber tubular structure.

[0169] Example 19

[0170] This embodiment provides a method for preparing a zinc hollow fiber electrode. The difference between this method and that in Embodiment 1 is that the binder used in step S1 is polyethersulfone. Other steps and methods are the same as in Embodiment 1 and will not be repeated here.

[0171] This embodiment also provides a zinc hollow fiber electrode, which is prepared by the zinc hollow fiber electrode preparation method of this embodiment, and the zinc hollow fiber electrode has a porous hollow fiber tubular structure.

[0172] Application Example 1

[0173] The zinc hollow fiber electrodes prepared in Examples 1-19 were applied to the electrocatalytic conversion of CO2, and CO2 was reduced using a potentiostatic method. The process included the following steps: CO2 was introduced into the zinc hollow fiber electrode, which was placed in an electrolyte solution. The anolyte was 3.0 M KCl and 3.0 M KOH. A voltage of -1.25 V vs. RHE was applied for CO2 electrocatalysis for 1 h, and CO and H2 products were obtained. The total current density, the Faraday current efficiency of CO, and the volume ratio of CO to H2 in the syngas were finally obtained (see Table 1).

[0174] Table 1. Results of the zinc hollow fiber electrodes prepared in Examples 1-19 in CO2 electrocatalytic conversion applications.

[0175]

[0176]

[0177] Application Example 2

[0178] The zinc hollow fiber electrode prepared in Example 1 was applied to the electrocatalytic conversion of CO2, and CO2 was reduced using a constant current method. The steps included: passing CO2 into the zinc hollow fiber electrode, placing the zinc hollow fiber electrode in an electrolyte solution (0.5 M KCl, 3.0 M KOH), and applying a current density of -1.0 A / cm². 2 Electrochemical reduction was carried out for 1 hour to obtain CO and H2 products. The potential was -1.52V vs. RHE. The Faraday current efficiency of CO was 82.2%, and the CO:H2 ratio in the syngas was 4.5:1.

[0179] Application Example 3

[0180] The zinc hollow fiber electrode prepared in Example 1 was applied to the electrocatalytic conversion of CO2, and CO2 was reduced using a potentiostatic method. The difference between the steps and those in Example 1 was that an electrochemical reduction was performed for 1 hour with a voltage of -1.34V vs. RHE, yielding CO and H2 products. The final total current density was -0.6 A / cm². 2 The Faraday current efficiency of CO is 92.5%, and the CO:H2 ratio in the syngas is 12.33:1.

[0181] Application Example 4

[0182] The zinc hollow fiber electrode prepared in Example 1 was applied to the electrocatalytic conversion of CO2, and CO2 was reduced using a potentiostatic method. The difference between the steps and those in Example 1 was that an electrochemical reduction was performed for 1 hour with a voltage of -1.43V vs. RHE, yielding CO and H2 products. The final total current density was -0.8A / cm². 2The Faraday current efficiency of CO is 87.5%, and the CO:H2 ratio in the synthesis gas is 7:1.

[0183] Application Example 5

[0184] The zinc hollow fiber electrode prepared in Example 1 was applied to the electrocatalytic conversion of CO2. CO2 was reduced using a potentiostatic method. The steps differed from those in Example 1 in that the anolyte was 0.5 M KHCO3, and an electrochemical reduction was performed for 1 hour at a voltage of -0.96 V vs. RHE, yielding CO and H2 products. The final total current density was -0.2 A / cm². 2 The Faraday current efficiency of CO is 93.3%, and the CO:H2 ratio in the synthesis gas is 13.92:1.

[0185] Application Example 6

[0186] The zinc hollow fiber electrode prepared in Example 1 was applied to the electrocatalytic conversion of CO2, and CO2 was reduced using a constant current method. The steps differed from those in Example 2 in that the anolyte was 0.5 M KHCO3, and the applied current density was -0.4 A / cm². 2 Electrochemical reduction was carried out for 1 hour to obtain CO and H2 products. The potential was -1.13V vs. RHE. The Faraday current efficiency of CO was 89.8%, and the CO:H2 ratio in the syngas was 8.8:1.

[0187] Application Example 7

[0188] The zinc hollow fiber electrode prepared in Example 1 was applied to the electrocatalytic conversion of CO2. CO2 was reduced using a potentiostatic method. The steps differed from those in Example 2 in that the anolyte was 0.5 M KHCO3, and an electrochemical reduction was performed for 1 hour at a voltage of -1.28 V vs. RHE, yielding CO and H2 products. The final total current density was -0.6 A / cm². 2 The Faraday current efficiency of CO is 86.7%, and the CO:H2 ratio in the synthesis gas is 8.8:1.

[0189] Application Example 8

[0190] The zinc hollow fiber electrode prepared in Example 1 was applied to the electrocatalytic conversion of CO2. CO2 was reduced using a potentiostatic method. The steps differed from those in Example 2 in that the anolyte was 0.5 M KHCO3, and an electrochemical reduction was performed for 1 h at a voltage of -1.44 V vs. RHE, yielding CO and H2 products. The final total current density was -0.8 A / cm². 2The Faraday current efficiency of CO is 81.7%, and the CO:H2 ratio in the syngas is 4.46:1.

[0191] In summary, the preparation method of this invention is simple and low-cost. A simple phase inversion method can efficiently prepare hollow fiber preforms. After calcination in an oxidizing atmosphere, an oxide precursor is obtained. Further in-situ electrochemical reduction of the oxide precursor yields a zinc hollow fiber electrode. The zinc hollow fiber electrode prepared by this invention can be applied to CO2 electrocatalytic reduction, particularly in the reaction of CO2 electrocatalytic conversion to CO and syngas. At room temperature and pressure, the Faradaic current efficiency for CO can reach up to 93.8%, and the ratio of CO to H2 in the generated syngas is adjustable. This zinc hollow fiber electrode exhibits excellent electrocatalytic activity, good selectivity for CO and syngas, high current density, and high stability, showing great application potential. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and has high industrial application value.

[0192] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing a zinc hollow fiber electrode, characterized by, The preparation method comprises the following steps: S1, at room temperature, a zinc source, an organic solvent and a binder are ball milled in a certain proportion to uniformly mix them to obtain a uniform slurry, and then the slurry is degassed in a vacuum drying box; the zinc source includes one or a combination of zinc powder and zinc oxide powder, the organic solvent includes one or a combination of N-methyl-2-pyrrolidone and N,N-dimethylformamide, and the binder includes one or a combination of polyethyleneimine and polyethersulfone; in the slurry, the mass percentage of the zinc source is 40wt%-70wt%, the mass percentage of the organic solvent is 20wt%-50wt%, and the mass percentage of the binder is 5wt%-15wt%; S2, the degassed slurry is extruded through a core liquid and a spinning head at a certain flow rate to form an initial fiber, and the initial fiber is then introduced into a coagulation liquid after passing through an air bath to undergo phase inversion to obtain a hollow fiber soft body; S3, after the hollow fiber soft body is washed and shaped, a hollow fiber green body is obtained; S4, the hollow fiber green body is placed in an oxidizing gas atmosphere, heated to a certain temperature at a certain heating rate, and calcined and oxidized to obtain an oxide precursor; the calcination and oxidation temperature is 500-1200℃; S5, in-situ electrochemically reducing the oxide precursor to obtain a zinc hollow fiber electrode; the in-situ electrochemically reducing specifically comprises the following steps: firstly performing cathodic potential reduction on the oxide precursor in an electrolyte, and then performing constant current reduction; the potential range of the potential reduction is -1.2 to -10 V vs. Ag / AgCl electrode, the time of the potential reduction is 5 min to 60 min; the current density of the constant current reduction is -0.1 to -1.0 A / cm 2 , and the time of the constant current reduction is 5 to 60 min.

2. The method of producing a zinc hollow fiber electrode according to claim 1, characterized by: In step S1, one or a combination of the following conditions is included: The particle size of the zinc source particles is 50nm-10μm; The shape of the zinc source particles is one or more of spherical, flaky, granular and irregular; The ball milling time is 12h-48h; The degassing time is 4h-24h.

3. The method of producing a zinc hollow fiber electrode according to claim 1, characterized by: In step S2, any one or a combination of the following conditions is included: The slurry is extruded through the spinning head at a flow rate of 5-25mL / min; The size of the spinning head is one or a combination of Φ1.0×0.3mm, Φ1.5×0.3mm, Φ1.5×0.5mm and Φ2.0×1.0mm; The flow rate of the core liquid is 5-25mL / min; The air distance between the spinning head and the liquid surface of the coagulation liquid is 0.1-3cm.

4. The method of producing a zinc hollow fiber electrode according to claim 1, characterized by: In step S4, any one or a combination of the following conditions is included: The oxidizing gas is air or oxygen; The flow rate of the oxidizing gas is 50-400mL / min; The heating rate is 0.5-8℃ / min; The calcination and oxidation time is 1-8h.

5. The method of producing a zinc hollow fiber electrode according to claim 1, characterized by: In step S5, the in-situ electrochemical reduction needs to be carried out in a gas atmosphere, and the gas atmosphere includes one or a combination of carbon dioxide, nitrogen and argon.

6. The method of producing a zinc hollow fiber electrode according to claim 1, characterized by: In step S5, the in-situ electrochemical reduction includes any one or a combination of the following conditions: The electrolyte is one or a combination of K2CO3, KHCO3, K2SO4, KOH, KCl, Na2CO3, NaHCO3, Na2SO4, NaOH and NaCl; The concentration of the electrolyte is 0.1-3M.

7. A zinc hollow fiber electrode produced by the production method of the zinc hollow fiber electrode according to any one of claims 1 to 6, characterized by: The zinc hollow fiber electrode is a porous hollow fiber tubular structure, comprising an inner tube surface and an outer tube surface; the wall thickness of the zinc hollow fiber electrode is 0.1mm-1mm, and the average pore size of the inner tube surface and the outer tube surface is 0.5μm-10μm.

8. Use of a zinc hollow fiber electrode according to claim 7, characterized in that: The zinc hollow fiber electrode is applied to the preparation of CO and synthesis gas by CO2 electrocatalytic conversion, and specifically comprises the following steps: introducing CO2 into the zinc hollow fiber electrode, placing the zinc hollow fiber electrode in an electrolyte, applying a constant potential or a constant current to electrochemically reduce CO2, electrocatalytically converting CO2 into CO, and CO and H2 proportion-adjustable synthesis gas.

9. Use of a zinc hollow fiber electrode according to claim 8, characterized in that: One or a combination of the following conditions is included: The electrolyte comprises a cathode liquid and an anode liquid, the cathode liquid comprises one or a combination of K2CO3, KHCO3, K2SO4, KCl, Na2CO3, NaHCO3, Na2SO4 and NaCl, and the anode liquid comprises one or a combination of K2CO3, KHCO3, K2SO4, KOH, Na2CO3, NaHCO3, Na2SO4 and NaOH; The concentration of the cathode liquid and the anode liquid is both 0.1-5M; The potential applied when the CO2 is electrochemically reduced is-0.5--10V vs. RHE; The current density applied when electrochemically reducing CO2 ranges from -0.01 to -5 A / cm2 2 .

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