CN112164806B - Preparation method of PTFE hollow fiber microporous gas diffusion electrode - Google Patents

Preparation method of PTFE hollow fiber microporous gas diffusion electrode Download PDF

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CN112164806B
CN112164806B CN202011040799.9A CN202011040799A CN112164806B CN 112164806 B CN112164806 B CN 112164806B CN 202011040799 A CN202011040799 A CN 202011040799A CN 112164806 B CN112164806 B CN 112164806B
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孙正宗
巴坤
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Fudan University
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/88—Processes of manufacture
    • H01M4/8803—Supports for the deposition of the catalytic active composition
    • H01M4/8807—Gas diffusion layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/8605—Porous electrodes
    • H01M4/8626—Porous electrodes characterised by the form
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/88—Processes of manufacture
    • H01M4/8825—Methods for deposition of the catalytic active composition
    • H01M4/8828—Coating with slurry or ink
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract

The invention provides a preparation method of a PTFE hollow fiber micropore gas diffusion electrode, which comprises the following steps: step 1, placing the PTFE hollow fiber microporous tube in oxygen or other reactive gas plasmas for plasma treatment, and regulating and controlling the hydrophilicity and hydrophobicity of the PTFE hollow fiber microporous tube; step 2, constructing conductive layers on the inner and outer surfaces of the PTFE hollow fiber microporous tube after plasma treatment by a chemical plating method, a thermal evaporation method or a solution coating and suction filtration method; and 3, sealing one end of the PTFE hollow fiber microporous tube with the constructed conductive layer by using insulating silica gel, fixing a gas channel on micropores of the PTFE hollow fiber microporous tube, and naturally drying in the air to obtain the PTFE hollow fiber microporous gas diffusion electrode.

Description

Preparation method of PTFE hollow fiber microporous gas diffusion electrode
Technical Field
The invention belongs to the technical field of gas diffusion electrode preparation, and particularly relates to a preparation method of a PTFE hollow fiber microporous gas diffusion electrode.
Background
The gas diffusion electrode is an electrode with a porous membrane structure made of hydrophobic polymer materials specially according to the principle of a fuel cell, so that a large amount of gas can reach the inside of the electrode and is communicated with electrolyte on the outer side of the electrode, a stable solid-liquid-gas three-phase interface is further formed under normal pressure, and high catalytic activity is shown. In the gas diffusion electrode, the gas diffusion layer (hydrophobic layer), the current collector layer (current conducting layer), and the catalytic layer (hydrophilic layer) are mainly divided. The gas diffusion layer generally has air permeability and hydrophobicity, and can prevent electrolyte from migrating in the diffusion layer so as to ensure that reaction gas smoothly reaches the catalyst layer. The current collector layer mainly plays a role in collecting electrons, guiding current and supporting. The catalyst layer is a site for catalytic reaction, and the gas supplied from the gas diffusion layer forms an electrochemical reaction activation site in this layer together with the catalyst and the electrolyte in the layer.
At present, with the continuous and deep scientific research, the gas diffusion electrode shows more and more prominent effects of improving the conversion efficiency and stability of the catalyst in the field of electrochemical catalysis. In recent years, researchers have experimented with different types of gas diffusion electrode constructions and catalyzed CO2Reduction of O2The fields of new Energy such as reduction and the like have been recognized to a great extent (Edward H.Sargent, Science, 360,783 (2018); Wenbo Ju, Advanced Energy Materials, 9, 1901514 (2019); Yi Cui, Nature Catalysis,1,592 2018). However, the gas diffusion electrodes of these methods usually need to construct a PTFE or PVDF planar structure by means of an electrospinning technique or special processing, and the preparation process is complicated and costly. And the prepared gas diffusion electrode only has a plane stacking structure. In addition, such gasesThe size of the body diffusion electrode is larger, the regulation and control range of the gas concentration is small, and the regulation and control method is single.
Disclosure of Invention
The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for producing a PTFE hollow fiber microporous gas diffusion electrode.
The invention provides a preparation method of a PTFE hollow fiber microporous gas diffusion electrode, which is characterized by comprising the following steps: step 1, placing the PTFE hollow fiber microporous tube in oxygen or other reactive gas plasmas for plasma treatment, and regulating and controlling the hydrophilicity and hydrophobicity of the PTFE hollow fiber microporous tube; step 2, constructing conductive layers on the inner and outer surfaces of the PTFE hollow fiber microporous tube after plasma treatment by a chemical plating method, a thermal evaporation method or a solution coating and suction filtration method; step 3, using insulating silica gel to seal one end of the PTFE hollow fiber microporous tube with the constructed conductive layer, fixing a gas channel on micropores of the PTFE hollow fiber microporous tube, and naturally drying in the air to obtain the PTFE hollow fiber microporous gas diffusion electrode, wherein a chemical plating method is to place the PTFE hollow fiber microporous tube in a chemical plating solution, respectively depositing conductive metals on the inner and outer surfaces of the PTFE hollow fiber microporous tube, a thermal evaporation method is to fix the PTFE hollow fiber microporous tube after plasma treatment on a heat-conducting disc substrate, then place the heat-conducting disc substrate in a cavity of a thermal evaporation plating instrument, after vacuum pumping, respectively evaporating conductive metals on the inner and outer surfaces of the PTFE hollow fiber microporous tube, a solution coating and suction filtration method is to slowly and uniformly coat a catalyst solution on the outer surface of the PTFE hollow fiber microporous tube after plasma treatment, and sequentially and uniformly coat a carbon black solution and a graphite solution after natural drying is completely, constructing a functional layer with double properties of electrocatalysis and gas diffusion, slowly and uniformly coating a catalyst solution on the inner surface of the PTFE hollow fiber microporous tube subjected to plasma treatment by suction filtration, and sequentially and uniformly coating a carbon black solution and a graphite solution after completely natural drying.
In the preparation method of the PTFE hollow fiber microporous gas diffusion electrode provided by the present invention, the method may further have the following characteristics: wherein the aperture of the PTFE hollow fiber microporous tube in the step 1 is 0.01-5 μm, the plasma power during plasma treatment is 5-100W, and the treatment time is 1-60 min.
In the preparation method of the PTFE hollow fiber microporous gas diffusion electrode provided by the present invention, the method may further have the following characteristics: wherein the concentration of the chemical plating solution in the chemical plating method is 0.1-5 mol/L, the reaction temperature is 30-90 ℃, and the reaction time is 1-60 min.
In the preparation method of the PTFE hollow fiber microporous gas diffusion electrode provided by the present invention, the method may further have the following characteristics: wherein the vacuum degree range of the thermal evaporation instrument in the thermal evaporation method is 1 × 10-4～1×10-3Pa, the evaporation speed of the conductive metal is 0.1-10 nm/s, and the evaporation thickness is 1-50 nm.
In the preparation method of the PTFE hollow fiber microporous gas diffusion electrode provided by the present invention, the method may further have the following characteristics: wherein, the catalyst solution in the method of solution coating and suction filtration is prepared by dispersing the catalyst in Nafion/isopropanol/H by ultrasound2The catalyst is obtained from a mixed solvent of O, the ultrasonic dispersion time is 60-300 min, the ultrasonic power is 50-200W, the concentration of the catalyst solution is 1-30 mg/mL, and the mass of the uniformly coated catalyst is 0.5-10 mg per square centimeter.
In the preparation method of the PTFE hollow fiber microporous gas diffusion electrode provided by the present invention, the method may further have the following characteristics: wherein, the carbon black solution in the method of solution coating and suction filtration is prepared by ultrasonically dispersing carbon black into Nafion/isopropanol/H2The O is obtained in a mixed solvent, the ultrasonic dispersion time is 30-180 min, the ultrasonic power is 50-200W, the concentration of a carbon black solution is 1-50 mg/mL, and the mass of uniformly coated carbon black is 1-50 mg per square centimeter.
In the preparation method of the PTFE hollow fiber microporous gas diffusion electrode provided by the present invention, the method may further have the following characteristics: wherein, the graphite solution in the method of solution coating and suction filtration is prepared by dispersing graphite into Nafion/isopropanol/H2The ultrasonic dispersion is carried out in a mixed solvent of O, the ultrasonic dispersion time is 30-120 min, the ultrasonic power is 50-200W, the concentration of the graphite solution is 0.1-20 mg/mL, and graphite is uniformly coatedThe mass of the catalyst is 0.1-20 mg per square centimeter.
Action and Effect of the invention
According to the preparation method of the PTFE hollow fiber microporous gas diffusion electrode, the hydrophilicity and the hydrophobicity of the PTFE hollow fiber microporous gas diffusion electrode can be regulated and controlled through plasma treatment, so that polarity controllable conversion is realized; because the gas channel is fixed in the micropores of the PTFE hollow fiber microporous tube, the gas channel has no requirements on the type of gas and the solubility in electrolyte, has strong universality, simple manufacturing process, simple and convenient operation, low cost and strong popularization; the gas outlet rate can be adjusted by adjusting the thickness of the carbon black and graphite composite layer during solution coating, and the gas concentration at the catalyst and the gas pressure in the PTFE hollow fiber microporous tube can be continuously adjusted by matching with the gas inlet flow; because the PTFE hollow fiber microporous tube has the knittability, the prepared PTFE hollow fiber microporous gas diffusion electrode can be knitted and patterned according to the actual required shape, and compared with the traditional gas diffusion electrode, the PTFE hollow fiber microporous gas diffusion electrode has stronger structural controllability and higher current density.
Drawings
FIG. 1 is a scanning electron microscope image of the porous structure of a PTFE hollow fiber microporous tube in an example of the present invention;
FIG. 2 is a schematic illustration of a process for preparing the outer surface of a PTFE hollow fiber microporous gas diffusion electrode in an embodiment of the present invention;
FIG. 3 is a schematic illustration of a process for preparing the inner surface of a PTFE hollow fiber microporous gas diffusion electrode in an embodiment of the present invention;
FIG. 4 is a schematic illustration of a PTFE hollow fiber microporous gas diffusion electrode that may be randomly woven and patterned in an embodiment of the present invention;
fig. 5 is a structural analysis and elemental characterization diagram of catalyst material MXene in an example of the present invention;
FIG. 6 is a pictorial view and scanning electron microscope view of a PTFE hollow fiber microporous gas diffusion electrode in an example of the present invention;
FIG. 7 is a schematic illustration of the gas diffusion mechanism in a PTFE hollow fiber microporous gas diffusion electrode in an embodiment of the present invention;
FIG. 8 is a graph of gas flow versus pressure for a PTFE hollow fiber microporous gas diffusion electrode in an embodiment of the present invention;
FIG. 9 is a schematic representation and physical representation of the NRR reaction of a PTFE hollow fiber microporous gas diffusion electrode in an embodiment of the present invention;
FIG. 10 is a graph of the NRR response performance of a PTFE hollow fiber microporous gas diffusion electrode in an example of the present invention.
Detailed Description
In order to make the technical means and functions of the present invention easy to understand, the present invention is specifically described below with reference to the embodiments and the accompanying drawings.
< example >
The preparation method of the PTFE hollow fiber microporous gas diffusion electrode of the embodiment comprises the following steps:
step 1, placing the PTFE hollow fiber microporous tube in oxygen or other reactive gas plasmas for plasma treatment, and regulating and controlling the hydrophilicity and hydrophobicity of the PTFE hollow fiber microporous tube.
The aperture of the PTFE hollow fiber microporous tube in the step 1 is 0.01-5 μm, the plasma power during plasma treatment is 5-100W, and the treatment time is 1-60 min. Preferably, the aperture is 0.1-1 μm, the plasma power is 20-60W, and the treatment time is 10-40 min.
FIG. 1 is a scanning electron microscope image of the porous structure of a PTFE hollow fiber microporous tube in an example of the present invention.
As shown in FIG. 1, the average pore size of the PTFE hollow fiber microporous tube was 0.4. mu.m.
And 2, constructing conductive layers on the inner and outer surfaces of the PTFE hollow fiber microporous tube subjected to plasma treatment by a chemical plating method, a thermal evaporation method or a solution coating and suction filtration method.
FIG. 2 is a schematic diagram of a process for preparing an outer surface of a PTFE hollow fiber microporous gas diffusion electrode in an embodiment of the present invention, and FIG. 3 is a schematic diagram of a process for preparing an inner surface of a PTFE hollow fiber microporous gas diffusion electrode in an embodiment of the present invention.
As shown in fig. 2 and 3, the chemical plating method places the PTFE hollow fiber microporous tube in a chemical plating solution to deposit conductive metals on the inner and outer surfaces of the PTFE hollow fiber microporous tube, respectively.
The concentration of the chemical plating solution in the chemical plating method is 0.1-5 mol/L, the reaction temperature is 30-90 ℃, and the reaction time is 1-60 min. Preferably, the concentration of the chemical plating solution is 1-3 mol/L, the reaction temperature is 40-60 ℃, and the reaction time is 10-50 min.
The thermal evaporation method is characterized in that the PTFE hollow fiber microporous tube after plasma treatment is fixed on a heat-conducting disc substrate, then the heat-conducting disc substrate is placed in a cavity of a thermal evaporation instrument, and after vacuum pumping is carried out, conductive metals are evaporated on the inner surface and the outer surface of the PTFE hollow fiber microporous tube respectively.
Vacuum degree range of thermal evaporation instrument in thermal evaporation method is 1 x 10-4～1×10-3Pa, the evaporation speed of the conductive metal is 0.1-10 nm/s, and the evaporation thickness is 1-50 nm. Preferably, the vacuum degree of the thermal evaporator is 3X 10-4～6×10-4Pa, the evaporation speed of the conductive metal is 0.4-1 nm/s, and the evaporation thickness is 10-30 nm.
The method comprises the steps of slowly and uniformly coating a catalyst solution on the outer surface of a PTFE hollow fiber microporous tube subjected to plasma treatment, sequentially and uniformly coating a carbon black solution and a graphite solution after the catalyst solution is completely naturally dried to construct a functional layer with double properties of electrocatalysis and gas diffusion, slowly and uniformly coating the catalyst solution on the inner surface of the PTFE hollow fiber microporous tube subjected to plasma treatment through suction filtration, and sequentially and uniformly coating the carbon black solution and the graphite solution after the catalyst solution is completely naturally dried.
The catalyst solution in the method of solution coating and suction filtration is prepared by dispersing the catalyst in Nafion/isopropanol/H through ultrasound2The catalyst is obtained from a mixed solvent of O, the ultrasonic dispersion time is 60-300 min, the ultrasonic power is 50-200W, the concentration of the catalyst solution is 1-30 mg/mL, and the mass of the uniformly coated catalyst is 0.5-10 mg per square centimeter. Preferably, the ultrasonic dispersion time of the catalyst solution is 100-200 min, the ultrasonic power is 80-180W, the concentration is 5-20 mg/mL, and the mass of the coated catalyst per square centimeter is 1-5 mg.
The carbon black solution in the method of solution coating and suction filtration is prepared by ultrasonically dispersing carbon black into Nafion/isopropanol/H2The O is obtained in a mixed solvent, the ultrasonic dispersion time is 30-180 min, the ultrasonic power is 50-200W, the concentration of a carbon black solution is 1-50 mg/mL, and the mass of uniformly coated carbon black is 1-50 mg per square centimeter. Preferably, the carbon black solution is ultrasonically dispersed for 60-120 min, the ultrasonic power is 80-120W, the concentration is 5-20 mg/mL, and the mass of the carbon black coated per square centimeter is 5-20 mg.
The graphite solution in the solution coating and suction filtration method is prepared by dispersing graphite into Nafion/isopropanol/H2The ultrasonic dispersion is carried out in a mixed solvent of O, the ultrasonic dispersion time is 30-120 min, the ultrasonic power is 50-200W, the concentration of the graphite solution is 0.1-20 mg/mL, and the mass of the uniformly coated graphite is 0.1-20 mg per square centimeter. Preferably, the graphite solution is subjected to ultrasonic dispersion for 50-100 min, the ultrasonic power is 50-120W, the concentration is 1-10 mg/mL, and the mass of the uniformly coated carbon black per square centimeter is 1-10 mg.
And 3, sealing one end of the PTFE hollow fiber microporous tube with the constructed conductive layer by using insulating silica gel, fixing a gas channel on micropores of the PTFE hollow fiber microporous tube, and naturally drying in the air to obtain the PTFE hollow fiber microporous gas diffusion electrode.
FIG. 4 is a schematic representation of a PTFE hollow fiber microporous gas diffusion electrode that may be randomly woven and patterned in an embodiment of the present invention.
As shown in fig. 4, the knittability of PTFE hollow fiber microporous tubes allows gas diffusion electrolysis to exhibit different patterned morphologies.
In this embodiment, the PTFE hollow fiber microporous gas diffusion electrode is prepared by a chemical plating method, a thermal evaporation method, and a solution coating and suction filtration method, respectively, and is tested by an electrocatalytic nitrogen reduction reaction, including the following steps:
firstly, placing a PTFE hollow fiber microporous tube with the average pore size of 0.4 mu m in oxygen plasma, and regulating and controlling the hydrophilicity of the microporous tube under the conditions that the power is 40W and the treatment time is 30 min.
And secondly, placing the PTFE hollow fiber microporous tube subjected to the oxygen plasma treatment in a silver mirror reaction solution with the concentration of 2mol/L, reacting for 30min at the temperature of 50 ℃, and then controllably depositing conductive metal silver on the surface of the PTFE hollow fiber microporous tube.
Thirdly, fixing the PTFE hollow fiber microporous tube after the oxygen plasma treatment at the thickness of 100 mu m and the area of 100cm2The square nickel sheet is placed in a cavity of a thermal evaporation instrument and is vacuumized to 5 multiplied by 10-4Pa, setting the gold evaporation rate to be 0.5nm/s and the thickness of the gold-plated layer to be 25 nm.
Fourthly, MXene is dispersed in Nafion/isopropanol/H2Dispersing the mixed solvent of O in ultrasonic for 180min, and slowly and uniformly coating the MXene catalyst solution with the MXene solution concentration of 10mg/mL on the surface of the PTFE hollow fiber microporous tube treated by the oxygen plasma with the ultrasonic power of 140W, wherein the coating mass is 1mg, and the coating area is 2cm2And naturally drying in the air to form the MXene catalyst layer.
Fig. 5 is a structural analysis and an elemental characterization diagram of the catalyst material MXene in the example of the present invention.
As shown in FIG. 5, the catalyst MXene is a high-quality monolayer flake with a size of about 0.5-2 μm.
The fifth step, dispersing the carbon black into Nafion/isopropanol/H2Ultrasonically dispersing for 120min in O mixed solvent with ultrasonic power of 100W, preparing carbon black solution with concentration of 20mg/mL, slowly and uniformly coating the carbon black solution on the surface of MXene catalyst layer with coating mass of 10mg and coating area of 2cm2And naturally drying in the air to form a carbon black layer.
Sixthly, dispersing graphite into Nafion/isopropanol/H2In the mixed solvent of O, carrying out ultrasonic dispersion for 60min with the ultrasonic power of 100W, preparing a graphite solution with the concentration of 5mg/mL, slowly coating the graphite solution on the surface of the carbon black layer, wherein the coating mass is 5mg, and the coating area is 2cm2And naturally dried in the air.
And seventhly, sealing one end of the PTFE hollow fiber microporous tube subjected to chemical plating, thermal evaporation and solution coating by using insulating silica gel, so that gas can only diffuse out from the diameter of the microporous tube, naturally drying in the air, and correspondingly obtaining the PTFE hollow fiber microporous gas diffusion electrode, wherein a real object image and a scanning electron microscope image are shown in fig. 6.
FIG. 7 is a schematic illustration of the gas diffusion mechanism in a PTFE hollow fiber microporous gas diffusion electrode in an embodiment of the present invention.
As shown in fig. 7, a PTFE hollow fiber microporous gas diffusion electrode prepared by solution coating and suction filtration is used for explaining the principle, one end of a PTFE hollow fiber microporous tube is an air inlet, and the other end is closed, at this time, the gas diffuses in the microporous tube according to the path i. As the pressure in the tube increases, the gas diffuses out of the micropores and along the interstices to the surface of the catalyst MXene, as shown by path (c). The carbon black/graphite layer on the outer layer of the catalyst has the functions of preventing gas from rapidly diffusing into the electrolyte and prolonging the time of the gas on the surface of the catalyst; meanwhile, the existence of a large amount of MXene catalyst surface electrolyte is avoided, and the inhibition of hydrogen evolution reaction is realized.
FIG. 8 is a graph of gas flow versus pressure for a PTFE hollow fiber microporous gas diffusion electrode in an example of the present invention.
As shown in fig. 8, as the gas flow rate increases, the pressure in the diffusion electrode gradually increases, and the threshold value is 220 KPa. The microporous tube closure structure will be broken when the pressure exceeds 220 KPa.
And step eight, connecting the PTFE hollow fiber microporous gas diffusion electrode into a working electrode through a conductive lead wire, so that the average resistance value between the conductive lead wire and the conductive layer of the PTFE hollow fiber microporous tube is about 50 omega.
The ninth step, carefully connecting the PTFE hollow fiber microporous gas diffusion electrode with 0.1MNa electrolyte2SO4In the electrochemical device of the electrolyte, the electrocatalytic nitrogen reduction reaction is carried out, wherein the nitrogen flow rate is 40 sccm.
FIG. 9 is a schematic and physical representation of the NRR reaction of a PTFE hollow fiber microporous gas diffusion electrode in an embodiment of the present invention.
As shown in FIG. 9, 1 is a reference electrode, 2 is a working electrode (communicating with a PTFE hollow fiber microporous gas diffusion electrode through a lead), 3 is a counter electrode (graphite rod electrode), 4 is a PTFE hollow fiber microporous gas diffusion electrodePorous gas diffusion electrode of N2And the air inlet is arranged at the position 5 of the cathode region, and the air outlet is arranged at the position 6 of the anode region. In the whole reaction system, a cathode region generates a nitrogen reduction reaction and a hydrogen evolution reaction, and an anode region generates an oxygen evolution reaction.
FIG. 10 is a graph of the NRR response performance of a PTFE hollow fiber microporous gas diffusion electrode in an example of the present invention.
As shown in FIG. 10, the three PTFE hollow fiber microporous gas diffusion electrodes prepared in this example all achieved reduction of nitrogen gas by NH of the PTFE hollow fiber microporous gas diffusion electrode obtained by solution coating3The yield was 15.52. mu. g h-1cm-2The Faraday Efficiency (FE) is 17.3%, which is obviously superior to the performance of Ag as a conductive layer and PTFE/Au, and can realize high-efficiency catalytic nitrogen reduction.
Effects and effects of the embodiments
According to the preparation method of the PTFE hollow fiber microporous gas diffusion electrode, the hydrophilicity and the hydrophobicity of the PTFE hollow fiber microporous gas diffusion electrode can be regulated and controlled through plasma treatment, so that polarity controllable conversion is realized; because the gas channel is fixed in the micropores of the PTFE hollow fiber microporous tube, the gas channel has no requirements on the type of gas and the solubility in electrolyte, has strong universality, simple manufacturing process, simple and convenient operation, low cost and strong popularization; the gas outlet rate can be adjusted by adjusting the thickness of the carbon black and graphite composite layer during solution coating, and the gas concentration at the catalyst and the gas pressure in the PTFE hollow fiber microporous tube can be continuously adjusted by matching with the gas inlet flow; because the PTFE hollow fiber microporous tube has the knittability, the prepared PTFE hollow fiber microporous gas diffusion electrode can be knitted and patterned according to the actual required shape, and compared with the traditional gas diffusion electrode, the PTFE hollow fiber microporous gas diffusion electrode has stronger structural controllability and higher current density.
The above embodiments are preferred examples of the present invention, and are not intended to limit the scope of the present invention.

Claims (7)

1. A preparation method of a PTFE hollow fiber micropore gas diffusion electrode is characterized by comprising the following steps:
step 1, placing a PTFE hollow fiber microporous tube in oxygen or other reactive gas plasmas for plasma treatment, and regulating and controlling the hydrophilicity and hydrophobicity of the PTFE hollow fiber microporous tube;
step 2, constructing conductive layers on the inner and outer surfaces of the PTFE hollow fiber microporous tube after plasma treatment by a chemical plating method, a thermal evaporation method or a solution coating and suction filtration method;
step 3, using insulating silica gel to seal one end of the PTFE hollow fiber microporous tube with the constructed conducting layer, fixing a gas channel on micropores of the PTFE hollow fiber microporous tube, and naturally drying in the air to obtain the PTFE hollow fiber microporous gas diffusion electrode,
wherein, the chemical plating method is to place the PTFE hollow fiber microporous tube in a chemical plating solution and respectively deposit conductive metal on the inner and outer surfaces of the PTFE hollow fiber microporous tube,
the thermal evaporation method fixes the PTFE hollow fiber microporous tube after plasma treatment on a heat-conducting disc substrate, then places the PTFE hollow fiber microporous tube in a cavity of a thermal evaporation instrument, after vacuum pumping, respectively evaporates conductive metals on the inner surface and the outer surface of the PTFE hollow fiber microporous tube,
the solution coating and suction filtration method comprises the steps of slowly and uniformly coating a catalyst solution on the outer surface of the PTFE hollow fiber microporous tube after plasma treatment, sequentially and uniformly coating a carbon black solution and a graphite solution after natural drying is completed, constructing a functional layer with double properties of electrocatalysis and gas diffusion, slowly and uniformly coating the catalyst solution on the inner surface of the PTFE hollow fiber microporous tube after plasma treatment through suction filtration, and sequentially and uniformly coating the carbon black solution and the graphite solution after natural drying is completed.
2. The method of making a PTFE hollow fiber microporous gas diffusion electrode of claim 1, characterized in that:
wherein the aperture of the PTFE hollow fiber microporous tube in the step 1 is 0.01-5 μm, the plasma power during plasma treatment is 5-100W, and the treatment time is 1-60 min.
3. The method of making a PTFE hollow fiber microporous gas diffusion electrode of claim 1, characterized in that:
wherein the concentration of the chemical plating solution in the chemical plating method is 0.1-5 mol/L, the reaction temperature is 30-90 ℃, and the reaction time is 1-60 min.
4. The method of making a PTFE hollow fiber microporous gas diffusion electrode of claim 1, characterized in that:
wherein the vacuum degree range of the thermal evaporation instrument in the thermal evaporation method is 1 × 10-4～1×10-3Pa, the evaporation speed of the conductive metal is 0.1-10 nm/s, and the evaporation thickness is 1-50 nm.
5. The method of making a PTFE hollow fiber microporous gas diffusion electrode of claim 1, characterized in that:
wherein the catalyst solution in the solution coating and suction filtration method is prepared by dispersing the catalyst in Nafion/isopropanol/H through ultrasound2The catalyst is obtained from a mixed solvent of O, the ultrasonic dispersion time is 60-300 min, the ultrasonic power is 50-200W, the concentration of the catalyst solution is 1-30 mg/mL, and the mass of the uniformly coated catalyst is 0.5-10 mg per square centimeter.
6. The method of making a PTFE hollow fiber microporous gas diffusion electrode of claim 1, characterized in that:
wherein the carbon black solution in the solution coating and suction filtration method is prepared by ultrasonically dispersing carbon black into Nafion/isopropanol/H2The carbon black is obtained in a mixed solvent of O, the ultrasonic dispersion time is 30-180 min, the ultrasonic power is 50-200W, the concentration of the carbon black solution is 1-50 mg/mL, and the mass of the uniformly coated carbon black is 1-50 mg per square centimeter.
7. The method of making a PTFE hollow fiber microporous gas diffusion electrode of claim 1, characterized in that:
wherein, the graphite solution in the method of solution coating and suction filtration is prepared by dispersing graphite into Nafion/isopropanol/H2The graphite is obtained from a mixed solvent of O, the ultrasonic dispersion time is 30-120 min, the ultrasonic power is 50-200W, the concentration of the graphite solution is 0.1-20 mg/mL, and the mass of the graphite which is uniformly coated is 0.1-20 mg per square centimeter.
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