CN114959761B - Preparation method and application of silver hollow fiber electrode - Google Patents

Preparation method and application of silver hollow fiber electrode Download PDF

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CN114959761B
CN114959761B CN202210480868.0A CN202210480868A CN114959761B CN 114959761 B CN114959761 B CN 114959761B CN 202210480868 A CN202210480868 A CN 202210480868A CN 114959761 B CN114959761 B CN 114959761B
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hollow fiber
silver
fiber electrode
electrode
silver hollow
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CN114959761A (en
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陈为
李守杰
董笑
宋艳芳
李桂花
魏伟
孙予罕
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Shanghai Advanced Research Institute of CAS
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/02—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/23—Carbon monoxide or syngas
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/055—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material
    • C25B11/057—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material consisting of a single element or compound
    • C25B11/061—Metal or alloy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis

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Abstract

The invention provides a preparation method and application of a silver hollow fiber electrode, wherein the preparation method comprises the following steps: s1, ball-milling and mixing silver powder, N-methyl-2-pyrrolidone and polyethyleneimine according to a certain proportion to obtain uniform slurry, and degassing; s2, extruding the slurry through a spinning head, and entering a coagulating liquid to undergo phase inversion to form hollow fiber soft bodies; s3, washing and shaping to obtain hollow fiber vitamin embryos; s4, willRoasting the hollow fiber vitamin embryo in an oxidizing gas atmosphere to obtain a first product; s5, placing the first intermediate product in a reducing gas atmosphere for heating reduction to obtain a second product; s6, performing electrochemical oxidation-reduction reaction on the second product to obtain the silver hollow fiber electrode. The electrode is applied to CO 2 Electrocatalytic conversion. The preparation method is simple, the cost is low, the morphology of the prepared electrode is controllable, and the electrode has good electrocatalytic activity, high selectivity, high current density and high stability.

Description

Preparation method and application of silver hollow fiber electrode
Technical Field
The invention belongs to the field of electrochemical reduction and conversion of carbon dioxide, and particularly relates to a preparation method and application of a silver hollow fiber electrode.
Background
The ever-increasing amount of energy demand and the over-exploitation of fossil fuels have led to a continual rise in the total amount of carbon dioxide emissions worldwide, causing increasingly serious environmental problems. Should be treated with carbon dioxide (CO) 2 ) Climate warming caused by excessive emission of greenhouse gases is particularly urgent, and CO 2 Emission reduction and utilization have become a research hotspot. And CO 2 As one of C1 raw materials with wider distribution in nature, CO is used for realizing carbon neutralization 2 The conversion and utilization of (c) is becoming a focus of attention in various countries. CO at present 2 Conversion and utilization predominate by thermochemical reduction, but the conditions required for such a process must be high temperature and pressure and CO will be present during the reduction process 2 Regeneration is not achieved by the method 2 Is effectively utilized and recycled. In comparison, electrochemical methods can skillfully avoid these harsh conditions, namely CO 2 The conversion provides a milder recycling means, and has good operability and practicabilityCO in the future 2 Has wider application prospect in the transformation and recovery.
CO at present 2 The research on electroreduction is not enough to reach the industrial level, and the main reasons are the problems of catalytic activity, catalytic selectivity, catalytic efficiency and the like, so the research on the electrode is to solve the problem of CO 2 Key to electroreduction. Due to the electronic structural characteristics of elemental silver, it is possible to further convert carbon-oxygen double bonds (c=o) in the carbon dioxide molecule into more reducing species, such as chemicals like CO, by breaking them. In addition, silver (Ag) electrodes have moderate hydrogen evolution overpotential and can properly suppress H 2 Is generated.
Conventional electrode electroreduction of CO 2 The maximum current density of (2) is subjected to CO 2 The hollow fiber has a rich pore structure, the unique structure of the hollow fiber can be used as an ideal place for reaction of gas raw materials, the whole contact surface can play a role in catalysis, the porous membrane on the surface of the hollow fiber can be fully contacted with electrolyte, the diffusion and migration of reactants and products are facilitated, the hollow fiber electrode can overcome the limitation of mass transfer and can be used under high current density and high pressure, so that the conversion efficiency and selectivity of the electrode are improved, self-supporting solid single metal is provided, considerable mechanical strength is provided, stable structure and performance are maintained in long-life test, huge application potential is shown, guidance is provided for practical application of electrocatalytic carbon dioxide, and the electrode is helpful for deep theoretical and experimental research.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a method for preparing a silver hollow fiber electrode and application thereof for solving the problem of CO electroreduction by the electrode in the prior art 2 The maximum current density of (2) is subjected to CO 2 Problems of low solubility in aqueous solutions and slow mass transfer limitations, as well as CO in the prior art 2 The problems of low catalytic activity, catalytic selectivity and catalytic efficiency of electroreduction.
To achieve the above and other related objects, the present invention provides a method for preparing a silver hollow fiber electrode, comprising the steps of:
s1, ball milling silver powder, N-methyl-2-pyrrolidone and polyethylenimine according to a certain proportion at room temperature, uniformly mixing to obtain uniform slurry, and standing the slurry in a vacuum drying oven for degassing;
s2, extruding the degassed slurry through a core liquid and a spinning head at a certain flow rate to form initial fibers, and enabling the initial fibers to enter a coagulating liquid for phase inversion after air bath to obtain hollow fiber soft bodies;
s3, washing and shaping the hollow fiber soft body to obtain a hollow fiber vitamin embryo;
S4, placing the hollow fiber vitamin embryo in an oxidizing gas atmosphere, heating to a certain temperature at a certain heating rate, and roasting and oxidizing to obtain a first product;
s5, placing the first intermediate product in a reducing gas atmosphere, heating to a certain temperature at a certain heating rate, and performing heating reduction to obtain a second product;
s6, performing electrochemical oxidation-reduction reaction on the second product to obtain the silver hollow fiber electrode.
Preferably, in the slurry in the step S1, the silver powder accounts for 30wt% to 80wt%, the N-methyl-2-pyrrolidone accounts for 5wt% to 65wt%, and the polyethyleneimine accounts for 5wt% to 15wt%.
Preferably, the particle size of the silver powder particles in the step S1 is 20 nm-10 μm.
Preferably, the silver powder particles in step S1 are one or more of spherical, spheroid, chain spherical, dendritic, and irregular shapes.
Preferably, the ball milling time in the step S1 is 10-30 hours.
Preferably, the degassing time in the step S1 is 2-12 hours.
Preferably, in step S2, the slurry is extruded through a spinneret at a flow rate of 1 to 20 ml/min.
Preferably, the size of the spinneret in step S2 is one or a combination of Φ1.0×0.3mm, Φ1.5×0.3mm, Φ1.5×0.5mm, Φ2.0×1.0 mm.
Preferably, the flow rate of the core liquid in the step S2 is 1-20 mL/min.
Preferably, in the step S2, the air distance between the spinning head and the liquid surface of the coagulating liquid is 0.2-5 cm.
Preferably, the oxidizing gas in step S4 is air or oxygen.
Preferably, in the step S4, the flow rate of the oxidizing gas is 10-300 mL/min.
Preferably, in the step S4, the heating rate is 1-20 ℃/min.
Preferably, the temperature of the calcination oxidation in the step S4 is 500-1000 ℃.
Preferably, the time of roasting and oxidizing in the step S4 is 4-10 hours.
Preferably, in the step S4, the outer diameter of the hollow fiber vitamin embryo is 0.5-5 mm, and the inner diameter thereof is 0.3-4.5 mm.
Preferably, the reducing gas in step S5 is one of hydrogen, argon and a hydrogen/argon mixture.
Preferably, in the step S5, the flow rate of the reducing gas is 10-300 mL/min.
Preferably, in the step S5, the heating rate is 1-20 ℃/min.
Preferably, the temperature of the heating reduction in the step S5 is 300-800 ℃.
Preferably, the heating and reducing time in the step S5 is 2-10 hours.
Preferably, the electrochemical oxidation-reduction reaction in step S6 specifically includes the following steps: the second product is anodized in situ in the electrolyte, followed by cathodic reduction.
Preferably, the electrolyte in step S6 is KHCO 3 、K 2 SO 4 、KOH、KCl、NaHCO 3 、Na 2 SO 4 One or a combination of NaCl.
Preferably, the concentration of the electrolyte in the step S6 is 0.1-3M.
Preferably, in the step S6, the anodic oxidation is performed at a potential of 0.1-10V vs. Ag/AgCl electrode, and the anodic oxidation time is 1-120 min.
Preferably, in the step S6, the potential of the cathode reduction is-0.1 to-10V vs. Ag/AgCl electrode, and the time of the cathode reduction is 1-120 min.
Preferably, the external diameter of the silver hollow fiber electrode obtained in the step S6 is 0.2-4 mm, and the internal diameter is 0.15-3.5 mm.
Preferably, the electrochemical oxidation-reduction reaction in step S6 specifically includes the steps of: and adopting cyclic voltammetry scanning for 50 circles at a scanning speed of 20mV/s and a potential range of-0.5-2.4V vs. Ag/AgCl.
The silver hollow fiber electrode prepared by the preparation method of the silver hollow fiber electrode is applied to CO 2 Electrocatalytic conversion of the CO 2 The electrocatalytic conversion comprises the following steps: CO is processed by 2 Introducing the silver hollow fiber electrode into an electrolyte, and applying constant potential or constant current to electrochemically reduce CO 2 CO is processed into 2 Electrocatalytic conversion to CO.
Preferably, the electrolyte comprises a catholyte and an anolyte, wherein the catholyte is KHCO 3 、K 2 SO 4 、KCl、NaHCO 3 、Na 2 SO 4 One or the combination of NaCl and KHCO as the anode liquid 3 、K 2 SO 4 、KCl、NaHCO 3 、Na 2 SO 4 One or a combination of NaCl.
Preferably, the concentration of the catholyte and the concentration of the anolyte are both 0.1-5M.
Preferably, the electric potential is-0.25 to-4.0V vs. RHE, and the current is-0.01 to-5A/cm 2 。
As described above, the preparation method and application of the silver hollow fiber electrode have the following beneficial effects:
the invention adopts a simple phase inversion method to prepare the hollow fiber vitaminRoasting the embryo in an oxidizing atmosphere and a reducing atmosphere successively to obtain a second product, and performing electrochemical oxidation reduction to obtain a silver hollow fiber electrode with a reconstructed outer surface for electrocatalytic reduction of CO 2 The electrode has the advantages of easily available raw materials, low cost, simple preparation, controllable morphology of the prepared electrode, good electrocatalytic activity, high selectivity, high current density and high stability.
The silver hollow fiber electrode can be applied to CO 2 In electrocatalytic reduction, the catalyst can be particularly applied to the reaction of generating CO by electrocatalytic conversion of carbon dioxide, and can solve the problem of CO in the prior art 2 CO in the solution phase due to the electrocatalytic conversion reaction to CO 2 The silver hollow fiber electrode prepared by the method is applied to CO, and has the problems of low solubility, low total current density, low CO Faraday selectivity, short service life of the electrode and the like caused by factors such as slow mass transfer 2 CO is generated by electrocatalytic conversion, the Faraday current efficiency of the CO can reach 20-99.9% at normal temperature and normal pressure, and the CO 2 The single pass conversion rate of CO is 1-90%, and the method has extremely high application prospect.
Drawings
Fig. 1 shows an SEM image of a cross section of a second product obtained in an embodiment of the invention.
Fig. 2 shows a partial enlarged view of fig. 1.
Fig. 3 shows an SEM image of a cross section of a silver hollow fiber electrode obtained in an embodiment of the present invention.
Fig. 4 shows a partial enlarged view of fig. 3.
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
Please refer to fig. 1-4. It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.
The invention adopts a simple phase inversion method to prepare hollow fiber vitamin embryo, and the hollow fiber vitamin embryo is baked in an oxidizing atmosphere and a reducing atmosphere successively to obtain a second product, and the second product is subjected to electrochemical oxidation reduction to obtain a silver hollow fiber electrode with a reconstructed outer surface for electrocatalytic reduction of CO 2 The electrode has the advantages of easily available raw materials, low cost, simple preparation, controllable morphology of the prepared electrode, good electrocatalytic activity, high selectivity, high current density and high stability; the silver hollow fiber electrode can be applied to CO 2 In electrocatalytic reduction, the catalyst can be particularly applied to the reaction of generating CO by electrocatalytic conversion of carbon dioxide, and can solve the problem of CO in the prior art 2 CO in the solution phase due to the electrocatalytic conversion reaction to CO 2 The silver hollow fiber electrode prepared by the method is applied to CO, and has the problems of low solubility, low total current density, low CO Faraday selectivity, short service life of the electrode and the like caused by factors such as slow mass transfer 2 CO is generated by electrocatalytic conversion, the Faraday current efficiency of the CO can reach 20-99.9% at normal temperature and normal pressure, and the CO 2 The single pass conversion rate of CO is 1-90%, and the method has extremely high application prospect.
The invention provides a preparation method of a silver hollow fiber electrode, which comprises the following steps:
s1, ball milling silver powder, N-methyl-2-pyrrolidone and polyethylenimine according to a certain proportion at room temperature, uniformly mixing to obtain uniform slurry, and standing the slurry in a vacuum drying oven for degassing.
As an example, in the slurry in the step S1, the silver powder accounts for 30wt% to 80wt%, such as 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, etc., in terms of mass%; the mass percentage of the N-methyl-2-pyrrolidone is 5wt% to 65wt%, such as 5wt%, 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 65wt%, etc.; the weight percentage of the polyethyleneimine is 5-15 wt%, such as 5wt%, 8wt%, 10wt%, 12wt%, 15wt%, and the like.
As an example, the particle size of the silver powder particles in step S1 is 20nm to 10 μm, such as 20nm, 50nm, 100nm, 200nm, 500nm, 1 μm, 5 μm, 10 μm, etc.
Preferably, the particle size of the silver powder particles is 50nm.
As an example, the silver powder particles in step S1 are one or more of spherical, spheroid, chain-spherical, dendritic, and irregular in shape.
Preferably, the silver powder particles are spherical in shape.
For example, the ball milling time in the step S1 is 10 to 30 hours, such as 10 hours, 15 hours, 20 hours, 25 hours, 30 hours, etc.
Preferably, the ball milling time is 18-24 h, such as 18h, 19h, 20h, 21h, 22h, 23h, 24h and the like.
For example, the degassing time in step S1 is 2-12 h, such as 2h, 4h, 6h, 8h, 10h, 12h, etc.
Preferably, the degassing time is 5-10 h, such as 5h, 6h, 7h, 8h, 9h, 10h, etc.
S2, extruding the degassed slurry through a core liquid and a spinning head at a certain flow rate, forming initial fibers along with the core liquid (inner coagulation bath), and enabling the initial fibers to enter into the coagulation liquid (outer coagulation bath) after passing through the air bath for phase inversion to obtain the hollow fiber soft body.
By way of example, the slurry in step S2 is extruded through the spinneret at a flow rate of 1 to 20mL/min, such as 1mL/min, 5mL/min, 10mL/min, 15mL/min, 20mL/min, etc.
Preferably, the flow rate of the slurry is 5mL/min.
As an example, the size of the spinneret in step S2 is one or a combination of Φ1.0×0.3mm, Φ1.5×0.3mm, Φ1.5×0.5mm, Φ2.0×1.0 mm.
Preferably, the spinneret has a size Φ1.0x0.3mm.
For example, the flow rate of the core liquid in the step S2 is 1-20 mL/min, such as 1mL/min, 5mL/min, 10mL/min, 15mL/min, 20mL/min, etc.
Preferably, the flow rate of the core liquid is 5mL/min.
As an example, the air distance between the spinneret and the liquid surface of the coagulation liquid in step S2 is 0.2-5 cm, such as 0.2cm, 0.5cm, 1cm, 2cm, 3cm, 4cm, 5cm, etc.
Preferably, the air distance between the spinneret and the coagulation liquid level is 1cm.
S3, washing and shaping the hollow fiber software to obtain the hollow fiber vitamin embryo.
Specifically, washing with a large amount of tap water, removing the organic solvent (N-methyl-2-pyrrolidone) in the hollow fiber soft body, shaping, specifically, straightening and fixing the hollow fiber tubular soft body, and naturally airing in the air.
And S4, placing the hollow fiber vitamin embryo in an oxidizing gas atmosphere, heating to a certain temperature at a certain heating rate, and roasting and oxidizing to obtain a first product.
As an example, the oxidizing gas in step S4 is air or oxygen.
For example, the flow rate of the oxidizing gas in step S4 is 10 to 300mL/min, such as 10mL/min, 50mL/min, 100mL/min, 150mL/min, 200mL/min, 250mL/min, 300mL/min, etc.
Preferably, the flow rate of the oxidizing gas is 100-200 mL/min, such as 100mL/min, 120mL/min, 140mL/min, 160mL/min, 180mL/min, 200mL/min, etc.
As an example, the temperature rising rate in step S4 is 1 to 20 ℃/min, such as 1 ℃/min, 5 ℃/min, 10 ℃/min, 15 ℃/min, 20 ℃/min, etc.
Preferably, the temperature rising rate is 1-10 ℃ per minute, such as 1 ℃/min, 2 ℃/min, 4 ℃/min, 6 ℃/min, 8 ℃/min, 10 ℃ per minute, and the like.
As an example, the temperature of the calcination oxidation in step S4 is 500 to 1000 ℃, such as 500 ℃, 600 ℃, 700 ℃, 800 ℃, 900 ℃, 1000 ℃, and the like.
Preferably, the temperature of the calcination oxidation is 500 to 800 ℃, such as 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃, 750 ℃, 800 ℃, and the like.
For example, the time of the calcination oxidation in step S4 is 4-10 h, such as 4h, 5h, 6h, 7h, 8h, 9h, 10h, etc.
Preferably, the roasting oxidation time is 6-8 hours, such as 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours and the like.
S5, placing the first intermediate product in a reducing gas atmosphere, heating to a certain temperature at a certain heating rate, and performing heating reduction to obtain a second product.
As an example, the reducing gas in step S5 is one of hydrogen, argon, and a hydrogen/argon mixture.
For example, the flow rate of the reducing gas in step S5 is 10 to 300mL/min, such as 10mL/min, 50mL/min, 100mL/min, 150mL/min, 200mL/min, 250mL/min, 300mL/min, etc.
Preferably, the flow rate of the reducing gas is 50-200 mL/min, such as 50mL/min, 100mL/min, 120mL/min, 140mL/min, 160mL/min, 180mL/min, 200mL/min, etc.
As an example, the temperature rising rate in step S5 is 1 to 20 ℃/min, such as 1 ℃/min, 5 ℃/min, 10 ℃/min, 15 ℃/min, 20 ℃/min, etc.
Preferably, the temperature rising rate is 1-5 ℃/min, such as 1 ℃/min, 2 ℃/min, 3 ℃/min, 4 ℃/min, 5 ℃/min and the like.
As an example, the temperature of the heating reduction in step S5 is 300 to 800 ℃, such as 300 ℃, 400 ℃, 500 ℃, 600 ℃, 700 ℃, 800 ℃, and the like.
Preferably, the temperature of the heating reduction is 300 to 500 ℃, such as 300 ℃, 350 ℃, 400 ℃, 450 ℃, 500 ℃, and the like.
For example, in step S5, the heating and reducing time is 2-10 h, such as 2h, 4h, 6h, 8h, 10h, etc.
Preferably, the heating and reducing time is 6-8 hours, such as 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, and the like.
S6, performing electrochemical oxidation-reduction reaction on the second product to obtain the silver hollow fiber electrode. The second product is also a silver hollow fiber electrode, after electrochemical oxidation-reduction treatment, the component of the hollow fiber electrode is still metallic silver, but the morphology is greatly changed, referring to fig. 1-4, the electrochemical activity and the specific surface area are greatly increased, the number of exposed active sites is also greatly increased, and finally the silver hollow fiber electrode with the reconstructed outer surface is obtained.
The embodiment of the invention provides a method for carrying out electrochemical oxidation-reduction reaction on a second product, which comprises the following steps: the second product is anodized in situ in the electrolyte, followed by cathodic reduction.
As an example, the electrolyte is KHCO 3 、K 2 SO 4 、KOH、KCl、NaHCO 3 、Na 2 SO 4 One or a combination of NaCl.
As an example, the concentration of the electrolyte is 0.1 to 3M, such as 0.1M, 0.5M, 1M, 2M, 3M, and the like.
Preferably, the electrolyte is 0.5M KHCO 3 。
For example, the anodic oxidation may be performed at a potential of 0.1-10V vs. Ag/AgCl electrode, such as 0.1V vs. Ag/AgCl electrode, 0.5V vs. Ag/AgCl electrode, 2V vs. Ag/AgCl electrode, 4V vs. Ag/AgCl electrode, 6V vs. Ag/AgCl electrode, 8V vs. Ag/AgCl electrode, 10V vs. Ag/AgCl electrode, etc., for a time of 1-120 min, such as 1min, 10min, 20min, 40min, 60min, 80min, 100min, 120min, etc.
Preferably, the anodic oxidation is carried out at a potential of 2.0V vs. Ag/AgCl electrode for a period of 4min.
As an example, the potential of the cathodic reduction is-0.1 to-10V vs. Ag/AgCl electrode, such as-0.1V vs. Ag/AgCl electrode, -0.5V vs. Ag/AgCl electrode, -1V vs. Ag/AgCl electrode, -2V vs. Ag/AgCl electrode, -4V vs. Ag/AgCl electrode, -6V vs. Ag/AgCl electrode, -8V vs. Ag/AgCl electrode, -10V vs. Ag/AgCl electrode, etc., and the cathodic reduction time is 1 to 120min, such as 1min, 10min, 20min, 40min, 60min, 80min, 100min, 120min, etc.
Preferably, the potential of cathodic reduction is-0.5V vs. Ag/AgCl electrode and the cathodic reduction time is 10min.
The embodiment of the invention also provides a method for carrying out electrochemical oxidation-reduction reaction on the second product, which comprises the following steps: and adopting cyclic voltammetry scanning for 50 circles at a scanning speed of 20mV/s and a potential range of-0.5-2.4V vs. Ag/AgCl.
Specifically, the roughness of the reconstructed thickness of the outer layer of the silver hollow fiber is controlled by controlling different sweeping speeds, different scanning voltage ranges and scanning turns.
The invention provides a silver hollow fiber electrode prepared by adopting the preparation method of the silver hollow fiber electrode, wherein the outer diameter of a hollow fiber vitamin embryo obtained in the step S3 is 0.5-5 mm, such as 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm and the like, and the inner diameter is 0.3-4.5 mm, such as 0.3mm, 0.5mm, 1mm, 2mm, 3mm, 4mm, 4.5mm and the like; the silver hollow fiber electrode obtained in the step S6 has an outer diameter of 0.2 to 4mm, such as 0.2mm, 0.5mm, 1mm, 2mm, 3mm, 4mm, etc., and an inner diameter of 0.15 to 3.5mm, such as 0.15mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, etc.
Specifically, the prepared silver hollow fiber electrode has a plurality of holes on the surface, the average value of the holes is 2-10 mu m, and the silver hollow fiber electrode is used for electrocatalytic reduction of CO 2 The catalytic activity is high.
The invention also provides application of the silver hollow fiber electrode, and the silver hollow fiber electrode is applied to CO 2 Electrocatalytic conversion, CO 2 The electrocatalytic conversion comprises the following steps: CO is processed by 2 Introducing into silver hollow fiber electrode, placing the silver hollow fiber electrode in electrolyte, and applying constant potential or constant current to electrochemically reduce CO 2 CO is processed into 2 Electrocatalytic conversion to CO.
Specifically, a silver hollow fiber electrode is placed in electrolyte, the bottom end of the silver hollow fiber electrode is sealed, and CO is introduced into the top end of the silver hollow fiber electrode 2 ，CO 2 The reaction raw material gas CO is forced to be dispersed out of porous walls of the silver hollow fiber electrode 2 Contact with electrolyte to strengthen the three-phase reaction interface between gas, liquid and solid and strengthen the mass transfer process of reactant and product.
In particular, CO 2 The total flow is 1-100 mL/min, and CO 2 Electric drierThe conversion temperature is 10-60 ℃.
As an example, the electrolyte includes a catholyte and an anolyte, the catholyte being KHCO 3 、K 2 SO 4 、KCl、NaHCO 3 、Na 2 SO 4 One or a combination of NaCl and KHCO as anode liquid 3 、K 2 SO 4 、KCl、NaHCO 3 、Na 2 SO 4 One or a combination of NaCl.
As an example, the concentration of the catholyte and the anolyte is 0.1-5M, such as 0.1M, 0.5M, 1M, 2M, 3M, 4M, 5M, etc.
Preferably, the catholyte is 1.5M KHCO 3 Anolyte of 1.5M KHCO 3 。
Specifically, the electric potential is-0.25 to-4.0V vs. RHE, such as-0.25V vs. RHE, -0.5V vs. RHE, -1.0V vs. RHE, -2.0V vs. RHE, -3.0V vs. RHE, -4.0V vs. RHE, and the current is-0.01 to-5A/cm 2 Such as-0.01A/cm 2 、-0.1A/cm 2 、-1A/cm 2 、-2A/cm 2 、-3A/cm 2 、-4A/cm 2 、-5A/cm 2 Etc.
Preferably, the voltage of the potential is-0.25 to-3.0V vs. RHE, such as-0.25V vs. RHE, -0.5V vs. RHE, -1.0V vs. RHE, -2.0V vs. RHE, -3.0V vs. RHE, and the like.
To further illustrate the silver hollow fiber electrode, method of manufacture and use of the present invention, the following specific examples are used.
Example 1
The embodiment provides a silver hollow fiber electrode, and the preparation method specifically comprises the following steps:
s1, mixing spherical silver powder with the particle size of 200nm, N-methyl-2-pyrrolidone and polyethyleneimine according to the proportion of 43wt%, 46wt% and 11wt% respectively at room temperature, ball milling for 24 hours at the rotating speed of 300r/min to obtain uniform slurry, and standing the slurry in a vacuum drying box for degassing for 5 hours;
s2, extruding the degassed slurry through a spinning head with the flow rate of 5mL/min and phi of 1.0 multiplied by 0.3mm, wherein initial fibers are formed along with the core liquid, and then enter a coagulating liquid for phase inversion after passing through an air bath to obtain hollow fiber soft bodies; wherein the core liquid is ultrapure water, the flow rate of the core liquid is 5mL/min, the coagulating liquid is tap water, and the air distance between the spinning head and the liquid level of the coagulating liquid is 1cm;
S3, washing the hollow fiber soft body with a large amount of tap water to remove the organic solvent, and shaping to obtain a hollow fiber vitamin embryo;
s4, heating the hollow fiber vitamin embryo to 600 ℃ at a heating rate of 1 ℃/min under an air atmosphere with a flow rate of 100mL/min for roasting and oxidizing for 6 hours so as to remove polyethyleneimine in the hollow fiber vitamin embryo, and simultaneously causing sintering of silver particles to obtain a first product;
s5, heating the first intermediate product to 300 ℃ at a heating rate of 1 ℃/min under the atmosphere of a hydrogen/argon mixed gas (the volume percentage of the hydrogen is 5%) with the flow rate of 100mL/min, and preserving heat for 4 hours to obtain a second product;
s6, second product in 0.5M KHCO 3 In-situ anodic oxidation for 4min followed by cathodic reduction for 10min, wherein the anodic oxidation potential is 2.0V vs. Ag/AgCl and the cathodic reduction potential is-0.5V vs. Ag/AgCl.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-0.8V vs. RHE, the reaction time is 1h, and the catholyte is 1.5M KHCO 3 Anolyte of 1.5M KHCO 3 Obtaining CO and H 2 The product had a total current density of 1.26A/cm 2 The Faraday current efficiency of CO reaches 91.1%, the selectivity is good, and the single pass conversion rate exceeds 50%.
Example 2
This example provides a silver hollow fiber electrode, which is prepared by a method different from that in example 1 in that: the spherical silver powder with the raw material of 10 mu m, N-methyl-2-pyrrolidone and polyethyleneimine in the step S1 are respectively mixed according to the proportion of 60wt%, 30wt% and 10 wt%; other methods and steps are the same as those of embodiment 1, and are not repeated here.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-0.8V vs. RHE, the reaction time is 1h, and the catholyte is 1.5M KHCO 3 Anolyte of 1.5M KHCO 3 Obtaining CO and H 2 The product had a total current density of 1.24A/cm 2 The Faraday current efficiency of CO reaches 88.3%, the selectivity is good, and the single pass conversion rate exceeds 50%.
Example 3
This example provides a silver hollow fiber electrode, which is prepared by a method different from that in example 1 in that: the raw materials in the step S1 are spherical silver powder with the concentration of 50nm, N-methyl-2-pyrrolidone and polyethyleneimine which are respectively mixed according to the proportion of 40wt%, 48wt% and 12 wt%; the degassed slurry in step S2 is extruded through a spinning head of phi 1.5X0.3 mm at a flow rate of 5mL/min through the core liquid; other methods and steps are the same as those of embodiment 1, and are not repeated here.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-0.8V vs. RHE, the reaction time is 1h, and the catholyte is 1.5M KHCO 3 Anolyte of 1.5M KHCO 3 Obtaining CO and H 2 The product had a total current density of 1.43A/cm 2 The Faraday current efficiency of CO reaches 93.5%, the selectivity is good, and the single pass conversion rate exceeds 50%.
Example 4
This example provides a silver hollow fiber electrode, which is prepared by a method different from that in example 1 in that: the raw materials in the step S1 are spherical silver powder with the concentration of 50nm, N-methyl-2-pyrrolidone and polyethyleneimine which are respectively mixed according to the proportion of 40wt%, 48wt% and 12 wt%; the degassed slurry in step S2 is extruded through a spinning head of phi 1.5X0.5 mm at a flow rate of 5mL/min through the core liquid; other methods and steps are the same as those of embodiment 1, and are not repeated here.
The silver hollow fiber is prepared by adopting the preparation methodThe dimension electrode, the embodiment also provides an application of the silver hollow fiber electrode, and the silver hollow fiber electrode uses a potentiostatic method to reduce CO 2 The applied voltage is-0.8V vs. RHE, the reaction time is 1h, and the catholyte is 1.5M KHCO 3 Anolyte of 1.5M KHCO 3 Obtaining CO and H 2 The product had a total current density of 1.35A/cm 2 The Faraday current efficiency of CO reaches 93.2%, the selectivity is good, and the single pass conversion rate exceeds 50%.
Example 5
This example provides a silver hollow fiber electrode, which is prepared by a method different from that in example 1 in that: the raw materials in the step S1 are spherical silver powder with the concentration of 50nm, N-methyl-2-pyrrolidone and polyethyleneimine which are respectively mixed according to the proportion of 40wt%, 48wt% and 12 wt%; the degassed slurry in step S2 is extruded through a spinning head of 2.0X1.0 mm with a flow rate of 5mL/min through the core liquid; other methods and steps are the same as those of embodiment 1, and are not repeated here.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-0.8V vs. RHE, the reaction time is 1h, and the catholyte is 1.5M KHCO 3 Anolyte of 1.5M KHCO 3 Obtaining CO and H 2 The product had a total current density of 1.33A/cm 2 The Faraday current efficiency of CO reaches 92.7%, the selectivity is good, and the single pass conversion rate exceeds 50%.
Example 6
This example provides a silver hollow fiber electrode, which is prepared by a method different from that in example 1 in that: the raw materials in the step S1 are spherical silver powder with the concentration of 50nm, N-methyl-2-pyrrolidone and polyethyleneimine which are respectively mixed according to the proportion of 40wt%, 48wt% and 12 wt%; other methods and steps are the same as those of embodiment 1, and are not repeated here.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-0.25V vs. RHE,the reaction time is 1h, and the catholyte is 1.5M KHCO 3 Anolyte of 1.5M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 99.7%, and has good selectivity.
Example 7
The preparation method of the silver hollow fiber electrode is the same as that of embodiment 6, and is not described here again.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-0.2V vs. RHE, the reaction time is 1h, and the catholyte is 1.5M KHCO 3 Anolyte of 1.5M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 92.9%, and has good selectivity.
Example 8
The preparation method of the silver hollow fiber electrode is the same as that of embodiment 6, and is not described here again.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-0.3V vs. RHE, the reaction time is 1h, and the catholyte is 2.0M KHCO 3 Anolyte of 2.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 99.5%, and has good selectivity.
Example 9
The preparation method of the silver hollow fiber electrode is the same as that of embodiment 6, and is not described here again.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-1.0V vs. RHE, the reaction time is 1h, the catholyte is 2.0M KCl, and the anolyte is 2.0M KHCO 3 Obtaining CO and H 2 The product of the process is obtained by mixing,the Faraday current efficiency of CO reaches 99.8%, and the selectivity is good.
Example 10
The preparation method of the silver hollow fiber electrode is the same as that of embodiment 6, and is not described here again.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-2.0V vs. RHE, the reaction time is 1h, the catholyte is 2.0M KCl, and the anolyte is 2.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 97.8%, and has good selectivity.
Example 11
The preparation method of the silver hollow fiber electrode is the same as that of embodiment 6, and is not described here again.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-3.0V vs. RHE, the reaction time is 1h, the catholyte is 2.0M KCl, and the anolyte is 2.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 92.8%, and has good selectivity.
Example 12
This example provides a silver hollow fiber electrode, the method of preparation of which differs from that of example 6 in that the second product in step S6 is KHCO at 0.5M 3 In electrolyte, a-0.5-1.2V vs. Ag/AgCl electrode is scanned for 50 circles by cyclic voltammetry at a scanning speed of 20 mV/s; other methods and steps are the same as those of embodiment 6, and will not be described here again.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-0.3V vs. RHE, the reaction time is 1h, the catholyte is 2.0M KCl, and the anolyte is 2.0M KHCO 3 ObtainingCO、H 2 The Faraday current efficiency of the product, CO, reaches 99.6%, and has good selectivity.
Example 13
The preparation method of the silver hollow fiber electrode is the same as that of embodiment 12, and is not described here again.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-1.0V vs. RHE, the reaction time is 1h, the catholyte is 2.0M KCl, and the anolyte is 2.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 98.8%, and has good selectivity.
Example 14
The preparation method of the silver hollow fiber electrode is the same as that of embodiment 12, and is not described here again.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-2.0V vs. RHE, the reaction time is 1h, the catholyte is 2.0M KCl, and the anolyte is 2.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 96.3%, and has good selectivity.
Example 15
The preparation method of the silver hollow fiber electrode is the same as that of embodiment 12, and is not described here again.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-2.5V vs. RHE, the reaction time is 1h, the catholyte is 2.0M KCl, and the anolyte is 2.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 92.3%, and has good selectivity.
Example 16
The preparation method of the silver hollow fiber electrode is the same as that of embodiment 12, and is not described here again.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-3.0V vs. RHE, the reaction time is 1h, the catholyte is 2.0M KCl, and the anolyte is 2.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 82.1%, and has good selectivity.
Example 17
The embodiment provides a silver hollow fiber electrode, the preparation method of which is different from embodiment 6 in that the second product in step S6 is scanned for 50 circles in 0.2M KOH electrolyte at a scanning speed of 20mV/S by cyclic voltammetry at a voltage of 0-2.4V vs. Ag/AgCl electrode; other methods and steps are the same as those of embodiment 6, and will not be described here again.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-0.3V vs. RHE, the reaction time is 1h, the catholyte is 2.0M KCl, and the anolyte is 2.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 99.1 percent, and has good selectivity.
Example 18
The preparation method of the silver hollow fiber electrode is the same as that of the embodiment 17, and is not repeated here.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-1.0V vs. RHE, the reaction time is 1h, the catholyte is 2.0M KCl, and the anolyte is 2.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 99.4%, and has good selectivity.
Example 19
The preparation method of the silver hollow fiber electrode is the same as that of the embodiment 17, and is not repeated here.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-2.0V vs. RHE, the reaction time is 1h, the catholyte is 2.0M KCl, and the anolyte is 2.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 93.4%, and has good selectivity.
Example 20
The preparation method of the silver hollow fiber electrode is the same as that of the embodiment 17, and is not repeated here.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-3.0V vs. RHE, the reaction time is 1h, the catholyte is 2.0M KCl, and the anolyte is 2.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 93.4%, and has good selectivity.
Example 21
The embodiment provides a silver hollow fiber electrode, the preparation method of which is different from embodiment 6 in that the second product in step S6 is in 0.5M KCl electrolyte, 0-1.5V vs. Ag/AgCl electrode, and the scanning speed of 20mV/S is used for 50 circles of cyclic voltammetry scanning; other methods and steps are the same as those of embodiment 6, and will not be described here again.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-0.3V vs. RHE, the reaction time is 1h, the catholyte is 2.0M KCl, and the anolyte is 2.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 99.8%, and has good selectivity.
Example 22
The preparation method of the silver hollow fiber electrode in this embodiment is the same as that of embodiment 21, and will not be described here again.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-1.0V vs. RHE, the reaction time is 1h, the catholyte is 2.0M KCl, and the anolyte is 2.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 99.3%, and has good selectivity.
Example 23
The preparation method of the silver hollow fiber electrode in this embodiment is the same as that of embodiment 21, and will not be described here again.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-2.0V vs. RHE, the reaction time is 1h, the catholyte is 2.0M KCl, and the anolyte is 2.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 95.2%, and has good selectivity.
Example 24
The preparation method of the silver hollow fiber electrode in this embodiment is the same as that of embodiment 21, and will not be described here again.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a potentiostatic method 2 The applied voltage is-3.0V vs. RHE, the reaction time is 1h, the catholyte is 2.0M KCl, and the anolyte is 2.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 90.8%, and has good selectivity.
Example 25
The preparation method and steps of the silver hollow fiber electrode are the same as those of embodiment 6, and are not repeated here.
The silver hollow fiber is prepared by adopting the preparation methodThe embodiment also provides an application of the silver hollow fiber electrode, and the silver hollow fiber electrode reduces CO by using a constant current method 2 Applying constant current of-0.1A/cm 2 The reaction time is 1h, the catholyte is 3.0M KCl, and the anolyte is 3.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 99.9%, and has good selectivity.
Example 26
The preparation method and steps of the silver hollow fiber electrode are the same as those of embodiment 6, and are not repeated here.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a constant current method 2 Applying a constant current of-1A/cm 2 The reaction time is 1h, the catholyte is 3.0M KCl, and the anolyte is 3.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 99.8%, and has good selectivity.
Example 27
The preparation method and steps of the silver hollow fiber electrode are the same as those of embodiment 6, and are not repeated here.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a constant current method 2 Applying constant current of-2A/cm 2 The reaction time is 1h, the catholyte is 3.0M KCl, and the anolyte is 3.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 97.9%, and has good selectivity.
Example 28
The preparation method and steps of the silver hollow fiber electrode are the same as those of embodiment 6, and are not repeated here.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a constant current method 2 Applying constant current of-3A-cm 2 The reaction time is 1h, the catholyte is 3.0M KCl, and the anolyte is 3.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 94.7%, and has good selectivity.
Example 29
The preparation method and steps of the silver hollow fiber electrode are the same as those of embodiment 6, and are not repeated here.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a constant current method 2 Applying constant current of-4A/cm 2 The reaction time is 1h, the catholyte is 3.0M KCl, and the anolyte is 3.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 87.9%, and has good selectivity.
Example 30
The preparation method and steps of the silver hollow fiber electrode are the same as those of embodiment 6, and are not repeated here.
The silver hollow fiber electrode prepared by the preparation method is also provided by the embodiment, and the application of the silver hollow fiber electrode is that the silver hollow fiber electrode reduces CO by using a constant current method 2 Applying constant current of-5A/cm 2 The reaction time is 1h, the catholyte is 3.0M KCl, and the anolyte is 3.0M KHCO 3 Obtaining CO and H 2 The Faraday current efficiency of the product, CO, reaches 80.5%, and has good selectivity.
In conclusion, the invention adopts a simple phase inversion method to prepare the hollow fiber vitamin embryo, and the hollow fiber vitamin embryo is baked in an oxidizing atmosphere and a reducing atmosphere successively to obtain a second product, and the second product is subjected to electrochemical oxidation reduction to obtain the silver hollow fiber electrode with the reconstructed outer surface for electrocatalytic reduction of CO 2 The electrode has the advantages of easily available raw materials, low cost, simple preparation, controllable morphology of the prepared electrode, good electrocatalytic activity, high selectivity, high current density and high stability; the silver hollow fiber electrode can be applied to CO 2 Electrocatalytic reductionIn particular to the reaction for generating CO by electrocatalytic conversion of carbon dioxide, can solve the problems of CO in the prior art 2 CO in the solution phase due to the electrocatalytic conversion reaction to CO 2 The silver hollow fiber electrode prepared by the method is applied to CO, and has the problems of low solubility, low total current density, low CO Faraday selectivity, short service life of the electrode and the like caused by factors such as slow mass transfer 2 CO is generated by electrocatalytic conversion, the Faraday current efficiency of the CO can reach 20-99.9% at normal temperature and normal pressure, and the CO 2 The single pass conversion rate of CO is 1-90%, and the method has extremely high application prospect. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims (5)

1. A method for preparing a silver hollow fiber electrode, which is characterized by comprising the following steps:
S1, ball milling silver powder, N-methyl-2-pyrrolidone and polyethylenimine according to a certain proportion at room temperature to uniformly mix the silver powder, the N-methyl-2-pyrrolidone and the polyethylenimine, obtaining uniform slurry, and standing the slurry in a vacuum drying oven for degassing; in the slurry in the step S1, the silver powder accounts for 30-80 wt% in terms of mass percent, the N-methyl-2-pyrrolidone accounts for 5-65 wt% in terms of mass percent, and the polyethyleneimine accounts for 5-15 wt%; the particle size of the silver powder particles is 20 nm-10 mu m; the ball milling time is 10-30 hours; the degassing time is 2-12 hours;
s2, extruding the degassed slurry through a spinning head at a certain flow rate, forming initial fibers along with the core liquid, and enabling the initial fibers to enter a coagulating liquid after air bath to undergo phase inversion to obtain hollow fiber soft bodies; the slurry is extruded through a spinning head at a flow rate of 1-20 mL/min; the size of the spinning head is one of phi 1.0 multiplied by 0.3mm, phi 1.5 multiplied by 0.5mm and phi 2.0 multiplied by 1.0 mm; the flow rate of the core liquid is 1-20 mL/min; the air distance between the spinning head and the liquid level of the coagulating liquid is 0.2-5 cm;
S3, washing and shaping the hollow fiber soft body to obtain a hollow fiber vitamin embryo;
s4, placing the hollow fiber vitamin embryo in an oxidizing gas atmosphere, heating to a certain temperature at a certain heating rate, and roasting and oxidizing to obtain a first product; the oxidizing gas is air or oxygen; the flow rate of the oxidizing gas is 10-300 mL/min; the temperature rising rate is 1-20 ℃ per minute; the roasting oxidation temperature is 500-1000 ℃; the roasting oxidation time is 4-10 hours;
s5, placing the first product in a reducing gas atmosphere, heating to a certain temperature at a certain heating rate, and performing heating reduction to obtain a second product; the reducing gas is one of hydrogen, argon or hydrogen-argon mixed gas; the flow rate of the reducing gas is 10-300 mL/min; the temperature rising rate is 1-20 ℃ per minute; the temperature of the heating reduction is 300-800 ℃; the heating and reducing time is 2-10 h;
s6, performing electrochemical oxidation-reduction reaction on the second product to obtain a silver hollow fiber electrode; the electrochemical oxidation-reduction reaction in step S6 specifically includes the following steps: scanning the second product in electrolyte at a scanning speed of 20mV/s for 50 circles by adopting cyclic voltammetry under the potential range of-0.5-2.4V vs. Ag/AgCl; the electrolyte is KHCO 3 、K 2 SO 4 、KOH、KCl、NaHCO 3 、Na 2 SO 4 One or more of NaCl; the concentration of the electrolyte is 0.1-3M; the outer diameter of the obtained silver hollow fiber electrode is 0.2-4 mm, and the inner diameter of the silver hollow fiber electrode is 0.15-3.5 mm.
2. The method for producing a silver hollow fiber electrode according to claim 1, wherein the silver powder particles in step S1 are one or more of spherical, spheroid, chain spherical, dendritic, and irregular in shape.
3. The method for preparing a silver hollow fiber electrode according to claim 1, wherein: in the step S4, the outer diameter of the hollow fiber vitamin embryo is 0.5-5 mm, and the inner diameter is 0.3-4.5 mm.
4. The use of the silver hollow fiber electrode prepared by the preparation method of the silver hollow fiber electrode according to any one of claims 1 to 3, characterized in that: the silver hollow fiber electrode is applied to CO 2 Electrocatalytic conversion of the CO 2 The electrocatalytic conversion comprises the following steps: CO is processed by 2 Introducing into silver hollow fiber electrode, placing the silver hollow fiber electrode in electrolyte, and applying constant potential to electrochemically reduce CO 2 CO is processed into 2 Electrocatalytic conversion to CO; wherein the constant potential is-2 to-0.3V vs. RHE.
5. The use of a silver hollow fiber electrode according to claim 4, comprising any one or a combination of the following conditions:
The electrolyte comprises a catholyte and an anolyte, wherein the catholyte is KHCO 3 、K 2 SO 4 、KCl、NaHCO 3 、Na 2 SO 4 One or more of NaCl, wherein the anolyte is KHCO 3 、K 2 SO 4 、KCl、NaHCO 3 、Na 2 SO 4 One or more of NaCl;
the concentration of the catholyte and the concentration of the anolyte are both 0.1-5M.
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