CN111777059B - Activation method of carbon nano tube carrier, carbon nano tube carrier and application thereof - Google Patents

Activation method of carbon nano tube carrier, carbon nano tube carrier and application thereof Download PDF

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CN111777059B
CN111777059B CN201910269574.1A CN201910269574A CN111777059B CN 111777059 B CN111777059 B CN 111777059B CN 201910269574 A CN201910269574 A CN 201910269574A CN 111777059 B CN111777059 B CN 111777059B
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carbon nanotube
nano tube
carbon
carbon nano
electrode
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CN111777059A (en
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邸江涛
曾沙
吕波
朱铖锋
李清文
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Suzhou Institute of Nano Tech and Nano Bionics of CAS
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/158—Carbon nanotubes
    • C01B32/168—After-treatment
    • 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
    • H01M4/90—Selection of catalytic material
    • H01M4/9075—Catalytic material supported on carriers, e.g. powder carriers
    • H01M4/9083—Catalytic material supported on carriers, e.g. powder carriers on carbon or graphite
    • 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
    • H01M4/90—Selection of catalytic material
    • H01M4/92—Metals of platinum group
    • H01M4/925—Metals of platinum group supported on carriers, e.g. powder carriers
    • H01M4/926—Metals of platinum group supported on carriers, e.g. powder carriers on carbon or graphite
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    • 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
    • Y02E60/50—Fuel cells

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Abstract

The invention discloses an activation method of a carbon nano tube carrier, the carbon nano tube carrier and application thereof. The activation method comprises the following steps: an electrode system mainly composed of a carbon nanotube assembly as a positive electrode and a counter electrode is placed in an electrolyte; and applying direct current constant current or direct current constant potential to the electrode system, and performing electrical defection treatment on the carbon nanotube assembly to obtain a defected carbon nanotube assembly. The method adopts an electrical defection method, is simpler and more convenient to operate, consumes less time, can perform oxygen functionalization on the carbon nano tube, and can greatly improve the defect degree of the carbon nano tube; the obtained carbon nano tube carrier is not only oxidized by the anode, but also rich edge and hole defects are produced on the carbon nano tube, the oxygen reduction catalytic performance of the carbon nano tube is greatly improved, and the carbon nano tube carrier can be further used as a carrier of an oxygen reduction catalyst to prepare the oxygen reduction catalyst and is applied to the field of fuel cells.

Description

Activation method of carbon nano tube carrier, carbon nano tube carrier and application thereof
Technical Field
The invention relates to an activation method of a carbon nano tube carrier, in particular to a carbon nano tube carrier applied to an oxygen reduction catalyst, a method for improving the oxygen reduction catalytic activity of the carbon nano tube carrier and an application thereof, belonging to the technical field of energy and cleaning.
Background
With the attention of human beings to renewable, sustainable and clean energy, the development of fuel cells is gradually emphasized, and research on cathode oxygen reduction catalysts of fuel cells is increasing. The traditional fuel cell cathode catalyst mainly comprises a noble metal catalyst which is mainly a commercialized 20wt% platinum-carbon catalyst, but the noble metal catalyst has the defects of high price, poor methanol poisoning resistance and poor stability, so that a plurality of experts and scholars at home and abroad are dedicated to developing an oxygen reduction catalyst with high catalytic performance, stability and low price to be applied to the fuel cell. Recently, partial substitution of oxygen reduction catalysts such as noble metals (alloys), transition metal oxides, doped carbon nanomaterials, transition metal-nitrogen-carbon composites and their related composite nanomaterials by transition metals has come into the field of view. The one-dimensional carbon nano tube has special nano structure, high conductivity, high mechanical strength, high specific surface area and other specific properties, is a good conductive additive and a good support carrier, and the nano material based on the carbon nano tube can realize the aims of long service life, stability, low cost and industrialization of the oxygen catalyst. However, due to the problems of micro surface and catalytic inertness of the original carbon nanotubes, the preparation of excellent oxygen reduction catalysts based on carbon nanotubes still needs to solve the supporting capacity and catalytic activity of carbon nanotubes, and the functional pretreatment of carbon nanotubes is very important. The common carbon nanotube functional pretreatment method at present mainly comprises a mixed concentrated acid oxidation method, wherein high-concentration strong oxidizing acid is added under the condition of heating reflux to chemically oxidize the carbon nanotube, and the defects of low safety and long time consumption are caused; in addition, an electrochemical activation method is also provided, in which a carbon nanotube assembly is used as a working electrode in a high potential interval, and a diluted acid is used as an electrolyte to perform cyclic voltammetry electrochemical oxidation on the carbon nanotube. At present, the above methods are only oxidation treatment of carbon nanotubes, and oxygen-containing functional groups are imparted on the surfaces of the carbon nanotubes, mainly in that the carbon nanotubes are subjected to oxygen functionalization to improve the hydrophilicity of the carbon nanotubes so as to enhance the loading capacity, but the improvement degree of the oxygen reduction catalytic performance of the carbon nanotubes is limited.
Disclosure of Invention
The main objective of the present invention is to provide a carbon nanotube carrier and an activation method thereof, so as to overcome the disadvantages in the prior art.
It is another object of the present invention to provide an oxygen reduction catalyst and a method for preparing the same.
In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:
the embodiment of the invention provides an activation method of a carbon nano tube carrier, which comprises the following steps:
putting an electrode system mainly consisting of a carbon nano tube assembly as a positive electrode and a counter electrode into electrolyte;
and applying direct current constant current or direct current constant potential to the electrode system, and performing electrical defection treatment on the carbon nanotube assembly to obtain a defected carbon nanotube assembly.
The embodiment of the invention also provides the defected carbon nano tube carrier prepared by the method.
The embodiment of the invention also provides application of the defected carbon nanotube carrier in preparation of an oxygen reduction catalyst or a fuel cell.
An embodiment of the present invention further provides an oxygen reduction catalyst, including:
the defected carbon nanotube support of claim 9; and
a catalytically active material supported on the carbon nanotube carrier.
The embodiment of the invention also provides a preparation method of the oxygen reduction catalyst, which comprises the following steps:
to provide the above-mentioned defected carbon nanotube carrier,
and loading a catalytically active material on the carbon nanotube carrier, thereby obtaining the oxygen reduction catalyst.
Embodiments of the present invention also provide a fuel cell, which includes the above-described defected carbon nanotube support or oxygen reduction catalyst.
Compared with the prior art, the invention has the advantages that:
1) The activation method of the carbon nano tube carrier provided by the invention adopts an electrical defection method, is simpler and more convenient to operate, consumes less time, can perform oxygen functionalization on the carbon nano tube, and can greatly improve the defect degree in the carbon tube;
2) The defected carbon nano tube carrier prepared by the method is not only oxidized by the anode, but also has abundant edge and hole defects on the carbon nano tube, thereby greatly improving the oxygen reduction catalytic performance of the carbon nano tube;
3) The defected carbon nano tube carrier prepared by the invention can be further used as a carrier of an oxygen reduction catalyst to prepare the oxygen reduction catalyst, and is applied to the field of fuel cells.
Drawings
Fig. 1 is a schematic diagram of an apparatus for electrically defecting a carbon nanotube network assembly according to an exemplary embodiment 1 of the present invention.
FIG. 2 is a schematic diagram of carbon quantum dots generated by the electrical defect treatment of the floating carbon nanotube film in accordance with an exemplary embodiment 1 of the present invention.
Fig. 3a and 3b are schematic views illustrating contact angles between the surface of the original floating CNT thin film and the surface of the electrically defected carbon nanotube thin film DCNT and water, respectively, in accordance with exemplary embodiment 1 of the present invention.
Fig. 4 is a raman graph of a CNT precursor film and a DCNT film in accordance with an exemplary embodiment 1 of the present invention.
FIG. 5 is a graph of oxygen reduction polarization curves of pristine CNTs and DCNTs in accordance with an exemplary embodiment 1 of the present invention.
Fig. 6 is a raman plot of the original ACNT array film and the electrically defected DACNT array film in accordance with an exemplary embodiment of the present invention 2.
FIG. 7 is a graph of oxygen reduction polarization of the original ACNT and DACNT in accordance with an exemplary embodiment of the present invention 2.
FIG. 8 is a graph showing the oxygen reduction polarization of NC-CNT obtained by the thermal treatment after the DCNT thin film treated by the electric defect treatment at different constant potentials in the exemplary embodiments 3 to 6 of the present invention.
FIG. 9 is a graph showing the oxygen reduction polarization of N-DCNT obtained after hydrothermal reaction of electrically defected DCNT films with ammonia water at different constant current densities in 7-10 according to an exemplary embodiment of the present invention.
Detailed Description
In view of the deficiencies in the prior art, the inventors of the present invention have made extensive studies and extensive practices to provide a technique for processing a carbon nanotube assembly by electrical defection, which comprises treating the carbon nanotube assembly with a high voltage/current density dc power supply using the carbon nanotube network assembly as a positive electrode, and peeling off carbon quantum dots from the carbon nanotubes to obtain a defected carbon nanotube assembly, and subsequently further loading different catalyst materials to obtain a defected carbon nanotube-based oxygen reduction catalyst for application to a fuel cell. The technical solution, its implementation and principles, etc. will be further explained as follows.
It is to be noted that the definitions of the terms mentioned in the description of the present invention are known to those skilled in the art. For example, some of the terms are defined as follows:
1. and (3) oxygen reduction reaction: oxygen is obtained through the reaction of reducing electrons into hydroxide ions.
2. Floating catalytic chemical vapor deposition: the chemical vapor deposition method is characterized in that reactants and carrier gas are injected into a high-temperature tube furnace, so that the synthesis of the carbon nano tube is realized in one step and the carbon nano tube is assembled into fiber. In this method, the raw material is freely reacted in the carrier gas after the injection, and a substrate for deposition is not required.
An aspect of an embodiment of the present invention provides a method for activating a carbon nanotube carrier, including:
an electrode system mainly composed of a carbon nanotube assembly as a positive electrode and a counter electrode is placed in an electrolyte;
and applying direct current constant current or direct current constant potential to the electrode system, and performing electrical defection treatment on the carbon nanotube assembly to obtain a defected carbon nanotube assembly.
In some embodiments, the carbon nanotube assembly is formed by chemical vapor deposition, preferably by floating catalyst chemical vapor deposition.
In some exemplary embodiments, the carbon nanotube assembly may be any one or a combination of two or more of a floating carbon nanotube film, a carbon nanotube array film, a carbon nanotube fiber, a carbon nanotube aerogel, a carbon nanotube foam, and the like, but is not limited thereto.
Further, the counter electrode has the same size as the positive electrode.
In some exemplary embodiments, the counter electrode may include any one of a platinum electrode, a graphite electrode, a floating carbon nanotube film, a carbon nanotube array film, a carbon nanotube fiber, a carbon nanotube aerogel, a carbon nanotube foam, and the like, but is not limited thereto.
In some exemplary embodiments, the electrolyte comprises a mixed solution of a strong alkali aqueous solution and absolute ethanol. The invention takes low-concentration alkaline ethanol solution as a medium and can strip out carbon quantum dots to manufacture defects on the carbon nano tube by direct-current constant-voltage or constant-current electrolysis.
Further, the strong base in the electrolyte may include any one or a combination of two or more of potassium hydroxide, sodium hydroxide, lithium hydroxide, and the like, but is not limited thereto.
Further, the concentration of the strong alkali aqueous solution is 0.1-10 mol/L.
Further, the volume ratio of the strong alkali aqueous solution to the absolute ethyl alcohol in the electrolyte can be 1:2 to 1:20.
in some exemplary embodiments, the dc constant potential is 1 to 60V.
In some exemplary embodiments, the DC constant current has a current density of 50-200 mA cm -2 。
In some exemplary embodiments, the time for the electrical defect treatment is 1-20 min.
In conclusion, the activation method of the carbon nanotube carrier provided by the invention adopts an electrical defection method, is simpler and more convenient to operate, consumes less time, can perform oxygen functionalization on the carbon nanotube, can greatly improve the defect degree of the carbon nanotube, and is very important for developing an oxygen reduction catalyst with high conductivity and high catalytic activity.
Another aspect of embodiments of the present invention provides a defected carbon nanotube carrier prepared by the foregoing method, the carbon nanotube carrier comprising carbon nanotubes exhibiting hydrophilicity and being rich in edge and/or hole defects.
In the invention, the defect degree of the anode carbon nanotube film after the carbon quantum dots are stripped is increased, the D peak intensity can be improved to 1.5-5 times, the oxygen reduction performance is enhanced, the initial overpotential can be reduced by 10mV-200mV, and the prepared defective carbon nanotube can be used for subsequently loading other catalytic active substances.
The defected carbon nanotube carrier prepared by the method not only is subjected to anodic oxidation, but also has abundant edge and hole defects on the carbon nanotube, and the oxygen reduction catalytic performance of the carbon nanotube is greatly improved.
Another aspect of an embodiment of the present invention also provides use of the aforementioned defected carbon nanotube support in the preparation of an oxygen reduction catalyst or a fuel cell.
The defected carbon nano tube carrier prepared by the method has greatly improved oxygen reduction catalytic performance, can be further used as a carrier of an oxygen reduction catalyst to load other active substances to prepare the oxygen reduction catalyst, and is applied to the field of fuel cells.
Another aspect of the embodiments of the present invention also provides a method for preparing a carbon quantum dot, including:
an electrode system mainly composed of a carbon nanotube assembly as a positive electrode and a counter electrode is placed in an electrolyte;
and applying a direct current constant current or a direct current constant potential to the electrode system to strip the carbon quantum dots from the carbon nanotube assembly.
Another aspect of an embodiment of the present invention also provides an oxygen reduction catalyst, including:
the foregoing defected carbon nanotube support; and
a catalytically active material supported on the carbon nanotube carrier.
In some exemplary embodiments, the catalytically active material may be derived from any one or a combination of two or more of graphene, platinum, palladium, silver, yttrium oxide, ruthenium oxide, manganese dioxide, cobalt oxide, nickel cobaltate, nickel hydroxide, iron oxide, tungsten oxide, zinc oxide, titanium oxide, polyaniline, polypyrrole, polythiophene, polydopamine, ammonia water, and the like, but is not limited thereto.
Further, the catalytic active substance is uniformly loaded on the surface of the single carbon nanotube or the carbon nanotube bundle.
Furthermore, the loading amount of the catalytic active substance on the carbon nano tube carrier is 0.1wt% -20 wt%.
Another aspect of an embodiment of the present invention also provides a method of preparing an oxygen reduction catalyst, including:
to provide a defective carbon nanotube carrier,
and loading a catalytically active material on the carbon nanotube carrier, thereby obtaining the oxygen reduction catalyst.
In some exemplary embodiments, the preparation method comprises: the catalytic active substance is loaded on the carbon nano tube carrier by adopting a mode of any one or a combination of more than two of electrochemical deposition, electrophoretic deposition, hydrothermal, solvothermal, physical spraying, physical dipping, chemical vapor deposition, electric heating, atomic layer deposition, evaporation, sputtering deposition and the like.
In some exemplary embodiments, the catalytically active material may be derived from any one or a combination of two or more of graphene, platinum, palladium, silver, yttrium oxide, ruthenium oxide, manganese dioxide, cobalt oxide, nickel cobaltate, nickel hydroxide, iron oxide, tungsten oxide, zinc oxide, titanium oxide, polyaniline, polypyrrole, polythiophene, polydopamine, ammonia water, and the like, but is not limited thereto.
Accordingly, another aspect of an embodiment of the present invention also provides a fuel cell comprising the foregoing defected carbon nanotube support or oxygen reduction catalyst.
The technical scheme of the invention is further explained in detail by a plurality of embodiments and the accompanying drawings. However, the examples are chosen only for the purpose of illustrating the invention and are not to be construed as limiting the scope of the invention.
Example 1
Fig. 1 is a diagram of an apparatus of an activation method for a carbon nanotube carrier, which includes the following steps:
step 1, preparing a floating CNT film by a floating catalytic chemical vapor deposition method: providing a carbon nano tube network macroscopic body prepared by a floating chemical vapor deposition method, wherein the preparation process comprises the following steps: the FCCVD tube furnace apparatus was heated to 1300 ℃ and an absolute ethanol solution containing 2wt.% ferrocene and 0.4wt.% thiophene was injected with a syringe pump at a rate of 20mL h -1 The carrier gas is Ar/H 2 Ar flow of mixed gas is 2200sccm, H 2 And the flow rate is 2000sccm, the original CNT aerogel floats out of the tail part and is collected by a roller, and the floating CNT film with the thickness of 10 micrometers is prepared by further compressing the roller after ethanol spraying and soaking.
Step 2.1mL of 10mol/L sodium hydroxide aqueous solution and 20mL of absolute ethyl alcohol are mixed to prepare electrolyte, a floating CNT film is taken as a positive electrode, platinum with the same area is taken as a counter electrode, and the electrolyte is immersed in the electrolyte; at constant current density of 50mA cm -2 And treating the electrode system for 10min to obtain the cathode carbon nanotube assembly DCNT with a certain degree of defection.
In this embodiment, the carbon nanotube film is oxidized and peeled off at a high current density, rich carbon quantum dots are peeled off from the carbon nanotubes and dissolved in the electrolyte, so that the color of the electrolyte changes from colorless to yellow, the concentration of the carbon quantum dots increases with the time, and the color of the electrolyte gradually deepens, as shown in fig. 2, which is 50mA cm in this embodiment -2 Schematic diagram of carbon quantum dot solutions with different concentrations obtained after processing the carbon nanotube assembly. Further, referring to fig. 3 to 5, after the carbon dots are stripped from the carbon nanotube assembly, on one hand, the electrochemical oxidation hydrophilicity is enhanced, and on the other hand, the holes/edges on the carbon nanotubes are increasedPlus, the intensity ratio I of the D peak to the G peak of the carbon nanotube D /I G An increase from 0.27 to 0.61 indicates an increase in the degree of carbon nanotube defects, and the carbon nanotubes after defection exhibit superior oxygen reduction catalytic performance with respect to the original untreated carbon nanotubes, with a decrease in the oxygen reduction onset potential overpotential of 60mV and an increase in the oxygen reduction current density.
The oxygen reduction catalyst was obtained by loading graphene, which is a catalytically active material, on the defected cathode carbon nanotube assembly DCNT obtained in this example, wherein the loading amount of the catalytically active material was 0.1wt%.
Example 2
This example provides a preparation of a defective CNT array film carrier, which includes the following steps:
step 1, preparing CNT array film by chemical vapor deposition method, depositing Al with thickness of 20nm on a silicon wafer substrate in sequence by using electron beam evaporation technology 2 O 3 And Fe catalyst with the thickness of 1nm are added into a tubular furnace, hydrogen, ethylene and argon are introduced, wherein the gas flow rates of the three gases are respectively 0.04L min -1 、0.05L min -1 、1.41L min -1 Growing at 745 deg.C for 14min to obtain single-wall carbon tube vertical array. Then, the film is repeatedly drawn by the single-walled carbon tube vertical array to obtain the ACNT array film with the thickness of 5 μm.
Step 2.1mL of 10mol/L sodium hydroxide aqueous solution and 20mL of absolute ethyl alcohol are mixed to prepare electrolyte, an ACNT array film is used as a positive electrode, platinum with the same area is used as a counter electrode, and the electrolyte is immersed in the electrolyte; at constant current density of 50mA cm -2 And treating the electrode system for 10min to obtain the DACNT (cathode carbon nanotube) assembly with a certain degree of defectiveness.
In this embodiment, as shown in FIG. 6, the 50mA cm in this embodiment -2 Processing the Raman spectrogram of the ACNT array film, and obtaining the intensity ratio I of the D peak to the G peak of the carbon nano tube D /I G An increase from 0.05 to 0.08 indicates an increase in the degree of carbon nanotube defects, and the carbon nanotubes after defection exhibit superior catalytic performance for oxygen reduction with respect to the original untreated carbon nanotubes, with a decrease in the overpotential for the onset of oxygen reduction of about 30mV, and with a decrease in the oxygen reduction potential of about 0mVThe reduction current density increases.
The oxygen reduction catalyst was obtained by loading platinum, which is a catalytically active material, on the defected cathode carbon nanotube assembly DCNT obtained in this example, wherein the loading amount of the catalytically active material was 20wt%.
Example 3
The embodiment provides activation of a carbon nanotube carrier and an oxygen electrode obtained based on the carbon nanotube carrier, which comprises the following steps of:
step 1, preparing a floating CNT film by a floating catalytic chemical vapor deposition method, namely providing a carbon nano tube network macroscopic body prepared by the floating chemical vapor deposition method, wherein the preparation process comprises the following steps: the FCCVD tube furnace apparatus was heated to 1300 ℃ and an absolute ethanol solution containing 2wt.% ferrocene and 0.4wt.% thiophene was injected with a syringe pump at a rate of 20mL h -1 The carrier gas is Ar/H 2 Ar flow of the mixed gas, 2200sccm, H 2 And the flow rate is 2000sccm, the original CNT aerogel floats out of the tail part and is collected by a roller, and the floating CNT film with the thickness of 10 micrometers is prepared by further compressing the roller after ethanol spraying and soaking.
Step 2.1mL of 10mol/L sodium hydroxide aqueous solution and 20mL of absolute ethyl alcohol are mixed to prepare electrolyte, a floating CNT film is taken as a positive electrode, platinum with the same area is taken as a counter electrode, and the electrolyte is immersed in the electrolyte; treating the anode carbon nanotube film for 10min by using a constant voltage of 1V in the above electrode system to obtain the anode carbon nanotube film with certain defect degree.
Step 3, taking the defective carbon nanotube film as a working electrode, taking a saturated calomel electrode as a reference electrode, taking a platinum wire electrode as a counter electrode, putting the three-electrode system into a solution of 0.5mol/L aniline and 1mol/L sulfuric acid, and performing cyclic voltammetry to obtain 50mV s -1 And performing electrodeposition for 100 cycles in a potential range of-0.2V-0.8V to obtain the defect carbon nanotube film deposited with polyaniline.
And 4, connecting two ends of the defective carbon nanotube film deposited with the polyaniline with copper foils, placing the defective carbon nanotube film in a quartz tube, introducing argon protective gas, and performing 6A electric heating treatment for 10min to prepare the NC-CNT-15 oxygen reduction electrode.
The defect carbon nanotube film obtained in this example was loaded with polyaniline, which is a catalytically active material, to obtain an oxygen reduction catalyst, wherein the loading amount of the catalytically active material was 10wt%.
Example 4
The embodiment provides activation of a carbon nano tube carrier and an oxygen electrode obtained based on the carbon nano tube carrier, which comprises the following steps:
step 1, preparing a floating CNT film by a floating catalytic chemical vapor deposition method, namely providing a carbon nano tube network macroscopic body prepared by the floating chemical vapor deposition method, wherein the preparation process comprises the following steps: the FCCVD tube furnace apparatus was heated to 1300 ℃ and an absolute ethanol solution containing 2wt.% ferrocene and 0.4wt.% thiophene was injected with a syringe pump at a rate of 20mL h -1 The carrier gas is Ar/H 2 Ar flow of mixed gas is 2200sccm, H 2 And the flow rate is 2000sccm, the original CNT aerogel floats out of the tail part and is collected by a roller, and the floating CNT film with the thickness of 10 micrometers is prepared by further compressing the roller after ethanol spraying and soaking.
Step 2.1mL of 10mol/L sodium hydroxide aqueous solution and 20mL of absolute ethyl alcohol are mixed to prepare electrolyte, a floating CNT film is taken as a positive electrode, platinum with the same area is taken as a counter electrode, and the electrolyte is immersed in the electrolyte; treating the carbon nanotube film with constant voltage of 20V in the electrode system for 10min to obtain the defected cathode carbon nanotube film.
Step 3, taking the defective carbon nanotube film as a working electrode, taking a saturated calomel electrode as a reference electrode, taking a platinum wire electrode as a counter electrode, putting the three-electrode system into a solution of 0.5mol/L aniline and 1mol/L sulfuric acid, and performing cyclic voltammetry to obtain 50mV s -1 And performing electrodeposition for 100 cycles in a potential range of-0.2V-0.8V to obtain the defect carbon nanotube film deposited with polyaniline.
And 4, connecting two ends of the defective carbon nanotube film deposited with the polyaniline with copper foils, placing the defective carbon nanotube film in a quartz tube, introducing argon protective gas, and performing 6A electric heating treatment for 10min to prepare the NC-CNT-20 oxygen reduction electrode.
Example 5
The embodiment provides activation of a carbon nanotube carrier and an oxygen electrode obtained based on the carbon nanotube carrier, which comprises the following steps of:
step 1, preparation by floating catalytic chemical vapor depositionProviding a carbon nano tube network macroscopic body prepared by a floating chemical vapor deposition method, wherein the preparation process comprises the following steps: the FCCVD tube furnace apparatus was heated to 1300 ℃ and an absolute ethanol solution containing 2wt.% ferrocene and 0.4wt.% thiophene was injected with a syringe pump at a rate of 20mL h -1 The carrier gas is Ar/H 2 Ar flow of mixed gas is 2200sccm, H 2 And the flow rate is 2000sccm, the original CNT aerogel floats out of the tail part and is collected by a roller, and the floating CNT film with the thickness of 10 micrometers is prepared by further compressing the roller after ethanol spraying and soaking.
Step 2.1mL of 10mol/L sodium hydroxide aqueous solution and 20mL of anhydrous ethanol are mixed to prepare electrolyte, a floating CNT film is used as a positive electrode, platinum with the same area is used as a counter electrode, and the electrolyte is immersed in the electrolyte; treating the carbon nanotube film with constant voltage of 25V in the electrode system for 10min to obtain the defected cathode carbon nanotube film.
Step 3, taking the defective carbon nanotube film as a working electrode, taking a saturated calomel electrode as a reference electrode, taking a platinum wire electrode as a counter electrode, putting the three-electrode system into a solution of 0.5mol/L aniline and 1mol/L sulfuric acid, and performing cyclic voltammetry to obtain 50mV s -1 And performing electrodeposition for 100 cycles in a potential interval of-0.2V-0.8V to obtain the defective carbon nanotube film deposited with polyaniline.
And 4, connecting two ends of the defective carbon nanotube film deposited with the polyaniline with copper foils, placing the defective carbon nanotube film in a quartz tube, introducing argon protective gas, and performing 6A electric heating treatment for 10min to prepare the NC-CNT-25 oxygen reduction electrode.
Example 6
The embodiment provides activation of a carbon nano tube carrier and an oxygen electrode obtained based on the carbon nano tube carrier, which comprises the following steps:
step 1, preparing a floating CNT film by a floating catalytic chemical vapor deposition method, namely providing a carbon nano tube network macroscopic body prepared by the floating chemical vapor deposition method, wherein the preparation process comprises the following steps: the FCCVD tube furnace apparatus was heated to 1300 ℃ and an absolute ethanol solution containing 2wt.% ferrocene and 0.4wt.% thiophene was injected with a syringe pump at a rate of 20mL h -1 The carrier gas is Ar/H 2 Ar flow of mixed gas is 2200sccm, H 2 Flow 2000sccm, originalAnd the initial CNT aerogel floats out of the tail part and is collected by a roller, and the floating CNT aerogel is sprayed with ethanol for soaking and then is compressed by a roller to prepare the floating CNT film with the thickness of 10 microns.
Step 2.1mL of 10mol/L sodium hydroxide aqueous solution and 20mL of absolute ethyl alcohol are mixed to prepare electrolyte, a floating CNT film is taken as a positive electrode, platinum with the same area is taken as a counter electrode, and the electrolyte is immersed in the electrolyte; treating the carbon nanotube film with constant voltage of 60V in the electrode system for 10min to obtain the defected anode carbon nanotube film.
Step 3, taking the defective carbon nanotube film as a working electrode, taking a saturated calomel electrode as a reference electrode, taking a platinum wire electrode as a counter electrode, putting the three-electrode system into a solution of 0.5mol/L aniline and 1mol/L sulfuric acid, and performing cyclic voltammetry to obtain 50mV s -1 Performing electrodeposition for 100 cycles in a potential range of-0.2V-0.8V to obtain the defect carbon nanotube film deposited with polyaniline
And 4, connecting two ends of the defective carbon nanotube film deposited with the polyaniline with copper foils, placing the defective carbon nanotube film in a quartz tube, introducing argon protective gas, and performing 6A electric heating treatment for 10min to prepare the NC-CNT-30 oxygen reduction electrode.
Example 7
The embodiment provides activation of a carbon nano tube carrier and an oxygen electrode obtained based on the carbon nano tube carrier, which comprises the following steps:
step 1, preparing a floating CNT film by a floating catalytic chemical vapor deposition method, namely providing a carbon nano tube network macroscopic body prepared by the floating chemical vapor deposition method, wherein the preparation process comprises the following steps: the FCCVD tube furnace apparatus was heated to 1300 ℃ and an absolute ethanol solution containing 2wt.% ferrocene and 0.4wt.% thiophene was injected with a syringe pump at a rate of 20mL h -1 The carrier gas is Ar/H 2 Ar flow of mixed gas is 2200sccm, H 2 The flow rate is 2000sccm, the original CNT aerogel is collected by a roller after floating from the tail, and the floating CNT film with the thickness of 10 micrometers is prepared by further compressing by using a roller after being sprayed and soaked by ethanol.
Step 2.10mL of 10mol/L sodium hydroxide aqueous solution and 20mL of anhydrous ethanol are mixed to prepare electrolyte, a floating CNT film is used as a positive electrode, platinum with the same area is used as a counter electrode, and the electrolyte is immersed in the electrolyte; at constant currentFlow density 50mA cm -2 And treating the electrode system for 10min to obtain the defected anode carbon nanotube film to a certain extent.
And 3, placing the defected carbon nanotube film in 30mL of concentrated ammonia water, transferring the defected carbon nanotube film to a reaction kettle, and reacting at 180 ℃ for 12 hours to prepare the N-DCNT-50 oxygen reduction electrode.
Example 8
The embodiment provides activation of a carbon nano tube carrier and an oxygen electrode obtained based on the carbon nano tube carrier, which comprises the following steps:
step 1, preparing a floating CNT film by a floating catalytic chemical vapor deposition method, namely providing a carbon nano tube network macroscopic body prepared by the floating chemical vapor deposition method, wherein the preparation process comprises the following steps: the FCCVD tube furnace apparatus was heated to 1300 ℃ and an absolute ethanol solution containing 2wt.% ferrocene and 0.4wt.% thiophene was injected with a syringe pump at a rate of 20mL h -1 The carrier gas is Ar/H 2 Ar flow of the mixed gas, 2200sccm, H 2 And the flow rate is 2000sccm, the original CNT aerogel floats out of the tail part and is collected by a roller, and the floating CNT film with the thickness of 10 micrometers is prepared by further compressing the roller after ethanol spraying and soaking.
Step 2.1mL of 8mol/L sodium hydroxide aqueous solution and 20mL of absolute ethyl alcohol are mixed to prepare electrolyte, a floating CNT film is used as a positive electrode, platinum with the same area is used as a counter electrode, and the electrolyte is immersed; at constant current density of 100mA cm -2 And treating the electrode system for 10min to obtain the anode carbon nanotube film with certain defect.
And 3, placing the defected carbon nanotube film in 30mL of concentrated ammonia water, transferring the defected carbon nanotube film into a reaction kettle, and reacting for 12 hours at 180 ℃ to prepare the N-DCNT-100 oxygen reduction electrode.
Example 9
The embodiment provides activation of a carbon nano tube carrier and an oxygen electrode obtained based on the carbon nano tube carrier, which comprises the following steps:
step 1, preparing a floating CNT film by a floating catalytic chemical vapor deposition method, namely providing a carbon nano tube network macroscopic body prepared by the floating chemical vapor deposition method, wherein the preparation process comprises the following steps: heating FCCVD tube furnace to 1300 deg.C, injecting into the tube furnace with injection pump containing 2wt% ferrocene and 0.4wt.% thiophene in absolute ethanol at an injection rate of 20mL h -1 The carrier gas is Ar/H 2 Ar flow of mixed gas is 2200sccm, H 2 And the flow rate is 2000sccm, the original CNT aerogel floats out of the tail part and is collected by a roller, and the floating CNT film with the thickness of 10 micrometers is prepared by further compressing the roller after ethanol spraying and soaking.
Step 2.5mL of 10mol/L sodium hydroxide aqueous solution and 20mL of absolute ethyl alcohol are mixed to prepare electrolyte, a floating CNT film is used as a positive electrode, platinum with the same area is used as a counter electrode, and the electrolyte is immersed in the platinum-based composite material; at constant current density 125mA cm -2 And treating the electrode system for 20min to obtain the anode carbon nanotube film with a certain degree of defection.
And 3, placing the defected carbon nanotube film in 30mL of concentrated ammonia water, transferring the defected carbon nanotube film into a reaction kettle, and reacting for 12 hours at 180 ℃ to prepare the N-DCNT-125 oxygen reduction electrode.
Example 10
The embodiment provides activation of a carbon nano tube carrier and an oxygen electrode obtained based on the carbon nano tube carrier, which comprises the following steps:
step 1, preparing a floating CNT film by a floating catalytic chemical vapor deposition method, namely providing a carbon nano tube network macroscopic body prepared by the floating chemical vapor deposition method, wherein the preparation process comprises the following steps: the FCCVD tube furnace apparatus was heated to 1300 ℃ and an absolute ethanol solution containing 2wt.% ferrocene and 0.4wt.% thiophene was injected with a syringe pump at a rate of 20mL h -1 The carrier gas is Ar/H 2 Ar flow of mixed gas is 2200sccm, H 2 And the flow rate is 2000sccm, the original CNT aerogel floats out of the tail part and is collected by a roller, and the floating CNT film with the thickness of 10 micrometers is prepared by further compressing the roller after ethanol spraying and soaking.
Step 2.1mL of 0.1mol/L sodium hydroxide aqueous solution and 20mL of absolute ethyl alcohol are mixed to prepare electrolyte, a floating CNT film is used as a positive electrode, platinum with the same area is used as a counter electrode, and the electrolyte is immersed; at constant current density of 200mA cm -2 And treating the electrode system for 1min to obtain the anode carbon nanotube film with a certain degree of defection.
And 3, placing the defected carbon nanotube film in 30mL of concentrated ammonia water, transferring the defected carbon nanotube film to a reaction kettle, and reacting at 180 ℃ for 12 hours to prepare the N-DCNT-200 oxygen reduction electrode.
Through the embodiments 1-10, it can be found that the method of the present invention using the electrical defection method is simpler and more convenient to operate, consumes less time, can perform oxygen functionalization on the carbon nanotube, and can greatly improve the defect degree of the carbon nanotube; the obtained carbon nano tube carrier is not only oxidized by the anode, but also rich edge and hole defects are produced on the carbon nano tube, the oxygen reduction catalytic performance of the carbon nano tube is greatly improved, and the carbon nano tube carrier can be further used as a carrier of an oxygen reduction catalyst to prepare the oxygen reduction catalyst and is applied to the field of fuel cells.
In addition, the present inventors have also conducted experiments with other raw materials and conditions and the like listed in the present specification by referring to the manner of example 1 to example 10, and have also produced a carbon nanotube carrier and an oxygen reduction catalyst having excellent oxygen reduction catalytic performance.
It should be understood that the above describes only some embodiments of the present invention and that various other changes and modifications may be affected therein by one of ordinary skill in the related art without departing from the scope or spirit of the invention.

Claims (5)

1. A method for preparing a carbon quantum dot, characterized by comprising:
an electrode system mainly composed of a carbon nanotube assembly as a positive electrode and a counter electrode is placed in an electrolyte;
applying direct current or direct current constant potential to the electrode system, and performing electric defect treatment on the carbon nano tube assembly to strip the carbon quantum dots from the carbon nano tube assembly to obtain the carbon quantum dots;
the carbon nano tube assembly is prepared and formed by a floating catalytic chemical vapor deposition method; the carbon nanotube assembly is any one or the combination of more than two of a floating carbon nanotube film, a carbon nanotube array film, carbon nanotube fibers, carbon nanotube aerogel and carbon nanotube foam;
the electrolyte comprises a mixed solution of a strong alkali aqueous solution and absolute ethyl alcohol; the strong base in the electrolyte comprises any one or the combination of more than two of potassium hydroxide, sodium hydroxide and lithium hydroxide; the concentration of the strong alkali aqueous solution is 0.1 to 10 mol/L; the volume ratio of the strong alkali aqueous solution to the absolute ethyl alcohol in the electrolyte is 1:2~1:20;
the voltage of the direct current constant potential is 1 to 60V; the current density of the direct current constant current is 50 to 200mA cm -2 。
2. The production method according to claim 1, characterized in that: the counter electrode is the same size as the positive electrode.
3. The method of claim 1, wherein: the counter electrode comprises any one of a platinum electrode, a graphite electrode, a floating carbon nanotube film, a carbon nanotube array film, carbon nanotube fibers, carbon nanotube aerogel and carbon nanotube foam.
4. The method for producing an electronic part according to claim 1, wherein the time for the electrical defection treatment is 1 to 20min.
5. A carbon quantum dot produced by the method of any one of claims 1 to 4.
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