CN111777059A - Activation method of carbon nanotube carrier, carbon nanotube carrier and application thereof - Google Patents

Abstract

The invention discloses an activation method of a carbon nanotube carrier, a carbon nanotube carrier and an application thereof. The activation method includes: placing an electrode system mainly composed of a carbon nanotube assembly as a positive electrode and a counter electrode into an electrolyte; Electrical defect treatment is performed to obtain a defective carbon nanotube assembly. The invention adopts the electrical defectization method, which is more convenient and time-consuming, can not only perform oxygen functionalization on the carbon nanotubes, but also greatly improve the degree of internal defects of the carbon nanotubes; the obtained carbon nanotube carrier is not only anodized, but also Rich edge and hole defects are produced on carbon nanotubes, which greatly improves the oxygen reduction catalytic performance of carbon nanotubes.

Description

Activation method of carbon nanotube carrier, carbon nanotube carrier and application thereof

technical field

The invention relates to a method for activating a carbon nanotube carrier, in particular to a carbon nanotube carrier applied to an oxygen reduction catalyst, a method for improving the oxygen reduction catalytic activity of the carbon nanotube carrier and its application, belonging to the technical field of energy and cleaning .

Background technique

With the attention of human beings on renewable, sustainable and clean energy, the development of fuel cells has been paid more and more attention, and the research on cathode oxygen reduction catalysts for fuel cells is increasing. The traditional fuel cell cathode catalysts are mainly noble metal catalysts, mainly commercial 20wt% platinum-carbon catalysts, but noble metal catalysts have the defects of high price, poor resistance to methanol poisoning, and poor stability. Develop high catalytic performance, stable, low-cost oxygen reduction catalysts for fuel cells. Recently, oxygen reduction catalysts such as transition metal partially substituted noble metals (alloys), transition metal oxides, doped carbon nanomaterials, transition metal-nitrogen-carbon composites and their related composite nanomaterials have come into the people's field of vision. Among them, one-dimensional carbon nanotubes have special nanostructures and specific properties such as high electrical conductivity, high mechanical strength, high specific surface area, etc., and are good conductive additives and support carriers. The goal of stability, low cost, and industrialization. However, due to the microscopic surface and catalytic inertness of pristine carbon nanotubes, the preparation of excellent oxygen reduction catalysts based on carbon nanotubes still needs to solve the loading capacity and catalytic activity of carbon nanotubes, and the functionalized pretreatment of carbon nanotubes is very important. At present, the common pretreatment methods of carbon nanotubes functionalization mainly include mixed concentrated acid oxidation method. In the case of heating and refluxing, high concentration of strong oxidizing acid is added to chemically oxidize carbon nanotubes. The disadvantages are low safety and long time consumption; In addition, there is an electrochemical activation method, in which carbon nanotubes are electrochemically oxidized by cyclic voltammetry using a carbon nanotube assembly as a working electrode and dilute acid as an electrolyte in a high potential range. At present, the above methods are only the oxidation treatment of carbon nanotubes, and oxygen-containing functional groups are endowed on the surface of carbon nanotubes. The main purpose is to perform oxygen functionalization on carbon nanotubes to improve the hydrophilicity of carbon nanotubes and thereby enhance the loading capacity. However, The improvement of the catalytic performance of carbon nanotubes for oxygen reduction is limited.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a carbon nanotube carrier and an activation method thereof to overcome the deficiencies in the prior art.

Another object of the present invention is to provide an oxygen reduction catalyst and a preparation method thereof.

In order to realize the foregoing invention purpose, the technical scheme adopted in the present invention includes:

An embodiment of the present invention provides a method for activating a carbon nanotube carrier, comprising:

An electrode system consisting mainly of a carbon nanotube assembly serving as a positive electrode and a counter electrode is placed in the electrolyte;

A DC constant current or DC constant potential is applied to the electrode system, and the carbon nanotube assembly is subjected to electrical defect treatment to obtain a defective carbon nanotube assembly.

Embodiments of the present invention also provide the defected carbon nanotube carrier prepared by the aforementioned method.

The embodiments of the present invention also provide the use of the aforementioned defective carbon nanotube carrier in preparing an oxygen reduction catalyst or a fuel cell.

The embodiment of the present invention also provides an oxygen reduction catalyst, which comprises:

The defective carbon nanotube support of claim 9; and

The catalytically active substance supported on the carbon nanotube carrier.

An embodiment of the present invention also provides a method for preparing an oxygen reduction catalyst, comprising:

providing the aforementioned defective carbon nanotube carrier,

And, a catalytically active substance is supported on the carbon nanotube carrier to obtain the oxygen reduction catalyst.

Embodiments of the present invention also provide a fuel cell comprising the aforementioned defective carbon nanotube carrier or oxygen reduction catalyst.

Compared with the prior art, the advantages of the present invention include:

1) The activation method of the carbon nanotube carrier provided by the present invention adopts the electric defect method to operate more easily and take less time, which can not only carry out oxygen functionalization of carbon nanotubes, but also greatly improve the degree of internal defects of the carbon nanotubes;

2) The defective carbon nanotube carrier prepared by the present invention is not only anodized, but also produces abundant edge and hole defects on the carbon nanotube, which greatly improves the oxygen reduction catalytic performance of the carbon nanotube;

3) The defective carbon nanotube carrier prepared by the present invention can be further used as a carrier of an oxygen reduction catalyst to prepare an oxygen reduction catalyst, which is applied to the field of fuel cells.

Description of drawings

FIG. 1 is a schematic diagram of an apparatus for electrical defect treatment of carbon nanotube network assemblies in a typical embodiment 1 of the present invention.

FIG. 2 is a schematic diagram of carbon quantum dots produced by electrical defect treatment of a floating carbon nanotube thin film according to an exemplary embodiment 1 of the present invention.

3a and 3b are schematic diagrams of the contact angles between the surface of the original floating CNT film and the carbon nanotube film DCNT after electrical defect treatment and water in a typical embodiment 1 of the present invention, respectively.

FIG. 4 is a Raman curve diagram of a pristine CNT thin film and a DCNT thin film in an exemplary embodiment 1 of the present invention.

5 is a graph of oxygen reduction polarization curves of pristine CNTs and DCNTs in an exemplary embodiment 1 of the present invention.

6 is a Raman curve diagram of the original ACNT array film and the DACCNT array film after electrical defect treatment in a typical embodiment 2 of the present invention.

7 is a graph of the oxygen reduction polarization curves of pristine ACNT and DACNT in an exemplary embodiment 2 of the present invention.

FIG. 8 is a graph of oxygen reduction polarization curves of NC-CNTs obtained by electrodepositing polyaniline on DCNT films subjected to electrodefective treatment at different constant potentials and then heat-treating them according to a typical embodiment 3-6 of the present invention.

9 is a graph of oxygen reduction polarization curves of N-DCNTs obtained by hydrothermally reacting DCNT thin films with electrodeficient treatment with ammonia water at different galvanostatic current densities in 7-10 according to an exemplary embodiment of the present invention.

Detailed ways

In view of the deficiencies in the prior art, after long-term research and a lot of practice, the inventors of the present invention have been able to propose the technical solution of the present invention, which is a technology for treating carbon nanotube assemblies by electrical defects, and the method uses carbon nanotube network assembly. The carbon nanotube assembly is treated with a high voltage/current density DC power supply, and the carbon quantum dots are peeled off from the carbon nanotube to obtain a defective carbon nanotube assembly, which can be further loaded with different catalyst materials. , and finally a defective carbon nanotube-based oxygen reduction catalyst can be obtained for use in fuel cells. The technical solution, its implementation process and principle will be further explained as follows.

First of all, it should be noted that the definitions of the terms mentioned in the specification of the present invention are known to those skilled in the art. For example, some of these terms are defined as follows:

1. Oxygen reduction reaction: The reaction in which oxygen is reduced by electrons to hydroxide ions.

2. Floating catalytic chemical vapor deposition method: It is a kind of chemical vapor deposition method. It injects reactants and carrier gas into a high-temperature tube furnace to synthesize and assemble carbon nanotubes into fibers in one step. In this method, the feedstock is free to react in a carrier gas after injection, and a substrate for deposition is not required.

One aspect of the embodiments of the present invention provides a method for activating a carbon nanotube carrier, comprising:

An electrode system consisting mainly of a carbon nanotube assembly serving as a positive electrode and a counter electrode is placed in the electrolyte;

A DC constant current or DC constant potential is applied to the electrode system, and the carbon nanotube assembly is subjected to electrical defect treatment to obtain a defective carbon nanotube assembly.

In some embodiments, the carbon nanotube assembly is formed by chemical vapor deposition, preferably by floating catalytic chemical vapor deposition.

In some typical implementation cases, the carbon nanotube assembly can be any one of floating carbon nanotube films, carbon nanotube array films, carbon nanotube fibers, carbon nanotube aerogels, carbon nanotube foams, etc. one or a combination of two or more, but not limited to this.

Further, the counter electrode and the positive electrode have the same size.

In some typical implementation cases, the counter electrode may include platinum electrodes, graphite electrodes, floating carbon nanotube films, carbon nanotube array films, carbon nanotube fibers, carbon nanotube aerogels, carbon nanotube foams, etc. any of, but not limited to.

In some typical implementation cases, the electrolyte includes a mixed solution of a strong alkaline aqueous solution and anhydrous ethanol. The invention uses a low-concentration alkali ethanol solution as a medium to strip carbon quantum dots through DC constant voltage or constant current electrolysis to manufacture defects on carbon nanotubes.

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, etc., 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 alkaline aqueous solution to the absolute ethanol in the electrolyte may be 1:2 to 1:20.

In some typical implementation cases, the voltage of the DC constant potential is 1-60V.

In some typical implementation cases, the current density of the DC constant current is 50-200 mA cm ^-2 .

In some typical implementation cases, the time for the electrical defect treatment is 1-20 minutes.

To sum up, the activation method of the carbon nanotube carrier provided by the present invention adopts the electric defect method, which is more convenient and time-consuming, and can not only perform oxygen functionalization on the carbon nanotubes, but also greatly improve the degree of internal defects of the carbon tubes. , which is very important for the development of oxygen reduction catalysts with high electrical conductivity and high catalytic activity.

Another aspect of the embodiments of the present invention provides a defective carbon nanotube support prepared by the aforementioned method, the carbon nanotubes contained in the carbon nanotube support are hydrophilic and have abundant edges and/or pores defect.

In the present invention, the defect degree of the positive carbon nanotube film after the peeled carbon quantum dots increases, the D peak intensity can be increased to 1.5-5 times, the oxygen reduction performance is enhanced, and the initial overpotential can be reduced by 10mV-200mV. The obtained defective carbon nanotubes can be used for subsequent loading of other catalytically active substances.

The defected carbon nanotube carrier prepared by the invention is not only anodized, but also produces abundant edge and hole defects on the carbon nanotube, which greatly improves the oxygen reduction catalytic performance of the carbon nanotube.

Another aspect of the embodiments of the present invention also provides the use of the aforementioned defective carbon nanotube carrier in preparing an oxygen reduction catalyst or a fuel cell.

The oxygen reduction catalytic performance of the defected carbon nanotube carrier prepared by the invention is greatly improved, and can be further used as a carrier of an oxygen reduction catalyst to support other active substances to prepare an oxygen reduction catalyst, which is applied to the field of fuel cells.

Another aspect of the embodiments of the present invention also provides a method for preparing carbon quantum dots, comprising:

An electrode system consisting mainly of a carbon nanotube assembly serving as a positive electrode and a counter electrode is placed in the electrolyte;

A DC constant current or a DC constant potential is applied to the electrode system, so that the carbon quantum dots are peeled off from the carbon nanotube assembly.

Another aspect of the embodiments of the present invention also provides an oxygen reduction catalyst, comprising:

The aforementioned defective carbon nanotube support; and

The catalytically active substance supported on the carbon nanotube carrier.

In some typical implementations, the catalytically active species may be derived from graphene, platinum, palladium, silver, yttrium oxide, ruthenium oxide, manganese dioxide, cobalt oxide, nickel cobaltate, nickel hydroxide, iron oxide, oxide Any one or a combination of two or more of tungsten, zinc oxide, titanium oxide, polyaniline, polypyrrole, polythiophene, polydopamine, ammonia water, etc., but not limited thereto.

Further, the catalytically active material is uniformly supported on the surface of a single carbon nanotube or a carbon nanotube bundle.

Further, the loading amount of the catalytically active material on the carbon nanotube carrier is 0.1 wt % to 20 wt %.

Another aspect of the embodiments of the present invention also provides a method for preparing an oxygen reduction catalyst, comprising:

to provide defective carbon nanotube supports,

And, a catalytically active substance is supported on the carbon nanotube carrier to obtain the oxygen reduction catalyst.

In some typical implementations, the preparation methods include: using electrochemical deposition, electrophoretic deposition, hydrothermal, solvothermal, physical spraying, physical dipping, chemical vapor deposition, electrical heating, atomic layer deposition, evaporation, and sputtering The catalytically active material is supported on the carbon nanotube carrier by any one or a combination of two or more of deposition and the like.

In some typical implementations, the catalytically active species may be derived from graphene, platinum, palladium, silver, yttrium oxide, ruthenium oxide, manganese dioxide, cobalt oxide, nickel cobaltate, nickel hydroxide, iron oxide, oxide Any one or a combination of two or more of tungsten, zinc oxide, titanium oxide, polyaniline, polypyrrole, polythiophene, polydopamine, ammonia water, etc., but not limited thereto.

Correspondingly, another aspect of the embodiments of the present invention further provides a fuel cell comprising the aforementioned defective carbon nanotube carrier or oxygen reduction catalyst.

The technical solutions of the present invention are further described in detail below through several embodiments and in conjunction with the accompanying drawings. However, the selected embodiments are only intended to illustrate the present invention and not to limit the scope of the present invention.

Example 1

A device diagram of a method for activating a carbon nanotube carrier provided in this embodiment is shown in FIG. 1 , which includes the following steps:

Step 1. Preparation of floating CNT thin film by floating catalytic chemical vapor deposition method: to provide a carbon nanotube network macro body prepared by floating chemical vapor deposition method. 2 wt.% ferrocene and 0.4 wt.% thiophene in absolute ethanol, the injection rate is 20 mL h ^-1 , the carrier gas is Ar/H ₂ mixed gas, the Ar flow rate is 2200 sccm, and the H ₂ flow rate is 2000 sccm, pristine CNT aerogel After floating from the tail, it was collected by a roller, sprayed with ethanol, and then further compressed by a roller to prepare a floating CNT film with a thickness of 10 microns.

Step 2. Mix 1mL of 10mol/L sodium hydroxide aqueous solution with 20mL of anhydrous ethanol to make an electrolyte, use the floating CNT film as the positive electrode, and the platinum of the same area as the counter electrode, and immerse in the electrolyte; use a constant current density of 50mA cm ^-2 above The electrode system was treated for 10 min to obtain a certain degree of defected positive carbon nanotube assembly DCNT.

In this embodiment, the carbon nanotube film undergoes oxidative etching and peeling at high current density, and the abundant carbon quantum dots peel off from the carbon nanotubes and dissolve in the electrolyte, so that the color of the electrolyte changes from colorless to yellow. Prolonged, the concentration of carbon quantum dots increases, and the color of the electrolyte gradually deepens. Figure 2 is a schematic diagram of carbon quantum dot solutions of different concentrations obtained after 50 mA cm ^-2 of carbon nanotube assemblies were treated in this example. Further, please refer to Fig. 3 to Fig. 5, after the carbon nanotube assembly itself is peeled off the carbon dots, on the one hand, the electrochemical oxidation of the hydrophilicity is enhanced, and on the other hand, the holes/edge defects on the carbon nanotubes increase, resulting in The increase in the intensity ratio of the D peak to the _G peak of the carbon nanotubes, I _D /IG, from 0.27 to 0.61 indicates that the degree of defects in the carbon nanotubes has increased. Compared with the original untreated carbon nanotubes, the defective carbon nanotubes show More excellent oxygen reduction catalytic performance, the oxygen reduction onset overpotential is reduced by 60mV, and the oxygen reduction current density is increased.

The catalytically active material graphene is supported on the defective positive carbon nanotube assembly DCNT obtained in this example to obtain an oxygen reduction catalyst, wherein the catalytically active material is loaded in an amount of 0.1 wt %.

Example 2

The preparation of a defected CNT array film carrier provided by this embodiment includes the following steps:

Step 1. Preparation of CNT array film by chemical vapor deposition method: use electron beam evaporation technology to deposit 20nm thick Al ₂ O ₃ and 1nm thick Fe catalyst in sequence on the silicon wafer substrate, add it into a tube furnace, and pass hydrogen, hydrogen, Ethylene and argon, the flow rates of the three gases were 0.04L min ^-1 , 0.05L min ^-1 , 1.41L min ^-1 respectively, and the vertical arrays of single-wall carbon tubes were prepared by growing at a high temperature of 745°C for 14 min. Then, the vertical array of single-walled carbon tubes was repeatedly drawn to obtain an ACNT array film with a thickness of 5 μm.

Step 2. Mix 1mL of 10mol/L sodium hydroxide aqueous solution with 20mL of anhydrous ethanol to make an electrolyte, take the ACNT array film as the positive electrode, and the platinum of the same area as the counter electrode, and immerse it in the electrolyte; use a constant current density of 50mA cm ^-2 above The electrode system was treated for 10 min to obtain a certain degree of defective positive carbon nanotube assembly DACNT.

In this embodiment, as shown in FIG. 6 , which is the Raman spectrum of the ACNT array film treated with 50 mA cm ⁻² in this embodiment, the intensity ratio of the _D peak to the _G peak of the carbon nanotubes, ID /IG, increases from 0.05 to 0.08 means that the degree of defects in carbon nanotubes increases. Compared with the original untreated carbon nanotubes, the deficient carbon nanotubes show better oxygen reduction catalytic performance. The reduction current density increases.

Catalytic active material platinum is supported on the defective positive carbon nanotube assembly DCNT obtained in this example to obtain an oxygen reduction catalyst, wherein the catalytic active material is supported in an amount of 20 wt %.

Example 3

The activation of a carbon nanotube carrier and an oxygen electrode obtained based on the carrier provided by this embodiment include the following steps:

Step 1. Floating catalytic chemical vapor deposition method to prepare floating CNT film: provide a carbon nanotube network macro body prepared by floating chemical vapor deposition method, and the preparation process is: heating the FCCVD tube furnace device to 1300 ° C, injecting the carbon nanotubes with a syringe pump containing 2 wt.% ferrocene and 0.4 wt.% thiophene in absolute ethanol, the injection rate is 20 mL h ^-1 , the carrier gas is Ar/H ₂ mixed gas, the Ar flow rate is 2200 sccm, and the H ₂ flow rate is 2000 sccm, pristine CNT aerogel After floating from the tail, it was collected by a roller, sprayed with ethanol, and then further compressed by a roller to prepare a floating CNT film with a thickness of 10 microns.

Step 2. Mix 1mL 10mol/L sodium hydroxide aqueous solution with 20mL absolute ethanol to make an electrolyte, use the floating CNT film as the positive electrode, and the platinum of the same area as the counter electrode, immerse in the electrolyte; apply a constant voltage of 1V to the above electrode system, process A certain degree of defective positive carbon nanotube film was obtained in 10 min.

Step 3. Using the defective carbon nanotube film as the working electrode, the saturated calomel electrode as the reference electrode, and the platinum wire electrode as the counter electrode, the three-electrode system was placed in a solution of 0.5 mol/L aniline and 1 mol/L sulfuric acid, with Cyclic voltammetry was performed at 50mV s ^-1 for 100 cycles in the potential range of -0.2 V to 0.8 V, and the defected carbon nanotube films of polyaniline were obtained.

Step 4. Connect the two ends of the defective carbon nanotube film of the deposited polyaniline to the copper foil, place it in a quartz tube, pass argon protective gas, and after 6A electric heating treatment for 10min, prepare the NC-CNT-15 oxygen reduction electrode .

The catalytically active material polyaniline is supported on the defective carbon nanotube film obtained in this example to obtain an oxygen reduction catalyst, wherein the catalytically active material is loaded in an amount of 10 wt %.

Example 4

The activation of a carbon nanotube carrier and an oxygen electrode obtained based on the carrier provided by this embodiment include the following steps:

Step 1. Floating catalytic chemical vapor deposition method to prepare floating CNT film: provide a carbon nanotube network macro body prepared by floating chemical vapor deposition method, and the preparation process is: heating the FCCVD tube furnace device to 1300 ° C, injecting the carbon nanotubes with a syringe pump containing 2 wt.% ferrocene and 0.4 wt.% thiophene in absolute ethanol, the injection rate is 20 mL h ^-1 , the carrier gas is Ar/H ₂ mixed gas, the Ar flow rate is 2200 sccm, and the H ₂ flow rate is 2000 sccm, pristine CNT aerogel After floating from the tail, it was collected by a roller, sprayed with ethanol, and then further compressed by a roller to prepare a floating CNT film with a thickness of 10 microns.

Step 2. Mix 1mL of 10mol/L sodium hydroxide aqueous solution with 20mL of absolute ethanol to make an electrolyte, use the floating CNT film as the positive electrode, and the platinum of the same area as the counter electrode, and immerse it in the electrolyte; apply a constant voltage of 20V to the above electrode system, process A certain degree of defective positive carbon nanotube film was obtained in 10 min.

Step 3. Using the defective carbon nanotube film as the working electrode, the saturated calomel electrode as the reference electrode, and the platinum wire electrode as the counter electrode, the three-electrode system was placed in a solution of 0.5 mol/L aniline and 1 mol/L sulfuric acid, with Cyclic voltammetry was performed at 50mV s ^-1 for 100 cycles in the potential range of -0.2 V to 0.8 V, and the defected carbon nanotube films of polyaniline were obtained.

Step 4. Connect both ends of the defective carbon nanotube film of the deposited polyaniline to copper foil, place it in a quartz tube, pass argon protective gas, and after 6A electric heating treatment for 10min, prepare the NC-CNT-20 oxygen reduction electrode .

Example 5

The activation of a carbon nanotube carrier and an oxygen electrode obtained based on the carrier provided by this embodiment include the following steps:

Step 1. Floating catalytic chemical vapor deposition method to prepare floating CNT film: provide a carbon nanotube network macro body prepared by floating chemical vapor deposition method, and the preparation process is: heating the FCCVD tube furnace device to 1300 ° C, injecting the carbon nanotubes with a syringe pump containing 2 wt.% ferrocene and 0.4 wt.% thiophene in absolute ethanol, the injection rate is 20 mL h ^-1 , the carrier gas is Ar/H ₂ mixed gas, the Ar flow rate is 2200 sccm, and the H ₂ flow rate is 2000 sccm, pristine CNT aerogel After floating from the tail, it was collected by a roller, sprayed with ethanol, and then further compressed by a roller to prepare a floating CNT film with a thickness of 10 microns.

Step 2. Mix 1mL of 10mol/L sodium hydroxide aqueous solution with 20mL of anhydrous ethanol to prepare an electrolyte, use the floating CNT film as the positive electrode, and the platinum of the same area as the counter electrode, and immerse it in the electrolyte; apply a constant voltage of 25V to the above electrode system, process A certain degree of defective positive carbon nanotube film was obtained in 10 min.

Step 3. Using the defective carbon nanotube film as the working electrode, the saturated calomel electrode as the reference electrode, and the platinum wire electrode as the counter electrode, the three-electrode system was placed in a solution of 0.5 mol/L aniline and 1 mol/L sulfuric acid, with Cyclic voltammetry was performed at 50mV s ^-1 for 100 cycles in the potential range of -0.2 V to 0.8 V, and the defected carbon nanotube films of polyaniline were obtained.

Step 4. Connect both ends of the defective carbon nanotube film of the deposited polyaniline with copper foil, place it in a quartz tube, pass argon protective gas, and after 6A electric heating treatment for 10min, prepare the NC-CNT-25 oxygen reduction electrode .

Example 6

The activation of a carbon nanotube carrier and an oxygen electrode obtained based on the carrier provided by this embodiment include the following steps:

Step 1. Floating catalytic chemical vapor deposition method to prepare floating CNT film: provide a carbon nanotube network macro body prepared by floating chemical vapor deposition method, and the preparation process is: heating the FCCVD tube furnace device to 1300 ° C, injecting the carbon nanotubes with a syringe pump containing 2 wt.% ferrocene and 0.4 wt.% thiophene in absolute ethanol, the injection rate is 20 mL h ^-1 , the carrier gas is Ar/H ₂ mixed gas, the Ar flow rate is 2200 sccm, and the H ₂ flow rate is 2000 sccm, pristine CNT aerogel After floating from the tail, it was collected by a roller, sprayed with ethanol, and then further compressed by a roller to prepare a floating CNT film with a thickness of 10 microns.

Step 2. Mix 1mL of 10mol/L sodium hydroxide aqueous solution with 20mL of anhydrous ethanol to make an electrolyte, use the floating CNT film as the positive electrode, and the platinum of the same area as the counter electrode, immerse in the electrolyte; apply a constant voltage of 60V to the above electrode system, process A certain degree of defective positive carbon nanotube film was obtained in 10 min.

Step 3. Using the defective carbon nanotube film as the working electrode, the saturated calomel electrode as the reference electrode, and the platinum wire electrode as the counter electrode, the three-electrode system was placed in a solution of 0.5 mol/L aniline and 1 mol/L sulfuric acid, with Cyclic voltammetry 50mV s ^-1 electrodeposited for 100 cycles in the potential range of -0.2 V-0.8 V to obtain the defected carbon nanotube films of polyaniline deposited

Step 4. Connect both ends of the defective carbon nanotube film of the deposited polyaniline with copper foil, place it in a quartz tube, pass argon protective gas, and after 6A electric heating treatment for 10min, prepare the NC-CNT-30 oxygen reduction electrode .

Example 7

The activation of a carbon nanotube carrier and an oxygen electrode obtained based on the carrier provided by this embodiment include the following steps:

Step 1. Floating catalytic chemical vapor deposition method to prepare floating CNT film: provide a carbon nanotube network macro body prepared by floating chemical vapor deposition method, and the preparation process is: heating the FCCVD tube furnace device to 1300 ° C, injecting the carbon nanotubes with a syringe pump containing 2 wt.% ferrocene and 0.4 wt.% thiophene in absolute ethanol, the injection rate is 20 mL h ^-1 , the carrier gas is Ar/H ₂ mixed gas, the Ar flow rate is 2200 sccm, and the H ₂ flow rate is 2000 sccm, pristine CNT aerogel After floating from the tail, it was collected by a roller, sprayed with ethanol, and then further compressed by a roller to prepare a floating CNT film with a thickness of 10 microns.

Step 2. Mix 10mL 10mol/L sodium hydroxide aqueous solution with 20mL absolute ethanol to make an electrolyte, use the floating CNT film as the positive electrode, and the platinum of the same area as the counter electrode, and immerse it in the electrolyte; use a constant current density of 50mA cm ^-2 above The electrode system was treated for 10 min to obtain a certain degree of defective positive carbon nanotube film.

Step 3. The defective carbon nanotube film was placed in 30 mL of concentrated ammonia water and transferred to a reaction kettle at 180° C. for 12 h to prepare an N-DCNT-50 oxygen reduction electrode.

Example 8

The activation of a carbon nanotube carrier and an oxygen electrode obtained based on the carrier provided by this embodiment include the following steps:

Step 1. Floating catalytic chemical vapor deposition method to prepare floating CNT film: provide a carbon nanotube network macro body prepared by floating chemical vapor deposition method, and the preparation process is: heating the FCCVD tube furnace device to 1300 ° C, injecting the carbon nanotubes with a syringe pump containing 2 wt.% ferrocene and 0.4 wt.% thiophene in absolute ethanol, the injection rate is 20 mL h ^-1 , the carrier gas is Ar/H ₂ mixed gas, the Ar flow rate is 2200 sccm, and the H ₂ flow rate is 2000 sccm, pristine CNT aerogel After floating from the tail, it was collected by a roller, sprayed with ethanol, and then further compressed by a roller to prepare a floating CNT film with a thickness of 10 microns.

Step 2. Mix 1mL 8mol/L sodium hydroxide aqueous solution with 20mL absolute ethanol to make an electrolyte, use the floating CNT film as the positive electrode, and the platinum of the same area as the counter electrode, and immerse it in the electrolyte; use a constant current density of 100mA cm ^-2 above The electrode system was treated for 10 min to obtain a certain degree of defective positive carbon nanotube film.

Step 3. The defective carbon nanotube film was placed in 30 mL of concentrated ammonia water, transferred to a reaction kettle at 180° C. for 12 h, and an N-DCNT-100 oxygen reduction electrode was prepared.

Example 9

The activation of a carbon nanotube carrier and an oxygen electrode obtained based on the carrier provided by this embodiment include the following steps:

Step 1. Floating catalytic chemical vapor deposition method to prepare floating CNT film: provide a carbon nanotube network macro body prepared by floating chemical vapor deposition method, and the preparation process is: heating the FCCVD tube furnace device to 1300 ° C, injecting the carbon nanotubes with a syringe pump containing 2 wt.% ferrocene and 0.4 wt.% thiophene in absolute ethanol, the injection rate is 20 mL h ^-1 , the carrier gas is Ar/H ₂ mixed gas, the Ar flow rate is 2200 sccm, and the H ₂ flow rate is 2000 sccm, pristine CNT aerogel After floating from the tail, it was collected by a roller, sprayed with ethanol, and then further compressed by a roller to prepare a floating CNT film with a thickness of 10 microns.

Step 2. 5mL of 10mol/L sodium hydroxide aqueous solution and 20mL of absolute ethanol were mixed to make an electrolyte, the floating CNT film was used as the positive electrode, the platinum of the same area was used as the counter electrode, and immersed in the electrolyte; the above electrode was immersed at a constant current density of 125mA cm ^-2 The system was treated for 20 min to obtain a certain degree of defective positive carbon nanotube film.

Step 3. The defective carbon nanotube film was placed in 30 mL of concentrated ammonia water and transferred to a reaction kettle at 180° C. for 12 h to prepare an N-DCNT-125 oxygen reduction electrode.

Example 10

The activation of a carbon nanotube carrier and an oxygen electrode obtained based on the carrier provided by this embodiment include the following steps:

Step 1. Floating catalytic chemical vapor deposition method to prepare floating CNT film: provide a carbon nanotube network macro body prepared by floating chemical vapor deposition method, and the preparation process is: heating the FCCVD tube furnace device to 1300 ° C, injecting the carbon nanotubes with a syringe pump containing 2 wt.% ferrocene and 0.4 wt.% thiophene in absolute ethanol, the injection rate is 20 mL h ^-1 , the carrier gas is Ar/H ₂ mixed gas, the Ar flow rate is 2200 sccm, and the H ₂ flow rate is 2000 sccm, pristine CNT aerogel After floating from the tail, it was collected by a roller, sprayed with ethanol, and then further compressed by a roller to prepare a floating CNT film with a thickness of 10 microns.

Step 2. 1mL of 0.1mol/L sodium hydroxide aqueous solution was mixed with 20mL of absolute ethanol to make an electrolyte. The floating CNT film was used as the positive electrode, and the platinum of the same area was used as the counter electrode, and immersed in the electrolyte; the constant current density was 200mA cm ^-2 at The above electrode system was treated for 1 min to obtain a certain degree of defective positive carbon nanotube film.

Step 3. The defective carbon nanotube film was placed in 30 mL of concentrated ammonia water and transferred to a reaction kettle at 180° C. for 12 h to prepare an N-DCNT-200 oxygen reduction electrode.

Through Examples 1-10, it can be found that the electrical defectization method in the present invention is simpler and less time-consuming to operate, which can not only perform oxygen functionalization on carbon nanotubes, but also greatly improve the degree of internal defects in the carbon tubes; The carbon nanotube support is not only anodized, but also produces abundant edge and hole defects on the carbon nanotube, which greatly improves the oxygen reduction catalytic performance of carbon nanotubes, and can be further used as a support for oxygen reduction catalysts to prepare oxygen reduction catalysts. Used in the field of fuel cells.

In addition, the inventors of the present application also conducted experiments with other raw materials and conditions listed in this specification with reference to the methods of Example 1-Example 10, and also obtained carbon nanotube supports with excellent oxygen reduction catalytic performance and Oxygen reduction catalyst.

It should be understood that the above descriptions are only some embodiments of the present invention, and it should be pointed out that for those of ordinary skill in the art, other modifications and improvements can also be made without departing from the inventive concept of the present invention. These all belong to the protection scope of the present invention.

Claims (17)

1. an activation method of a carbon nanotube carrier, is characterized in that comprising: An electrode system consisting mainly of a carbon nanotube assembly serving as a positive electrode and a counter electrode is placed in the electrolyte; A DC constant current or DC constant potential is applied to the electrode system, and the carbon nanotube assembly is subjected to electrical defect treatment to obtain a defective carbon nanotube assembly. 2. The method for activating a carbon nanotube carrier according to claim 1, wherein the carbon nanotube assembly is formed by chemical vapor deposition, preferably by floating catalytic chemical vapor deposition; And/or, the carbon nanotube assembly is any one or two or more of floating carbon nanotube films, carbon nanotube array films, carbon nanotube fibers, carbon nanotube aerogels, and carbon nanotube foams. combination. 3. The method for activating a carbon nanotube carrier according to claim 1, wherein the counter electrode and the positive electrode have the same size; and/or the counter electrode comprises a platinum electrode, a graphite electrode, and a floating carbon nanotube Any one of film, carbon nanotube array film, carbon nanotube fiber, carbon nanotube aerogel, and carbon nanotube foam. 4 . The method for activating a carbon nanotube carrier according to claim 1 , wherein the electrolyte comprises a mixed solution of a strong alkaline aqueous solution and anhydrous ethanol. 5 . 5. The method for activating carbon nanotube carriers according to claim 4, wherein the strong base in the electrolyte comprises any one or two or more of potassium hydroxide, sodium hydroxide, and lithium hydroxide. and/or, the concentration of the strong alkali aqueous solution is 0.1-10 mol/L; and/or, the volume ratio of the strong alkali aqueous solution to absolute ethanol in the electrolyte is 1:2-1:20. 6 . The method for activating a carbon nanotube carrier according to claim 1 , wherein the voltage of the DC constant potential is 1-60V. 7 . 7 . The method for activating a carbon nanotube carrier according to claim 1 , wherein the current density of the DC constant current is 50-200 mA cm ^-2 . 8 . 8 . The method for activating a carbon nanotube carrier according to claim 1 , wherein the time for the electrical defect treatment is 1-20 min. 9 . 9. A defective carbon nanotube support produced by the method of any one of claims 1-8. 10. Use of the defective carbon nanotube support of claim 9 in the preparation of an oxygen reduction catalyst or a fuel cell. 11. An oxygen reduction catalyst, characterized in that comprising: The defective carbon nanotube support of claim 9; and The catalytically active substance supported on the carbon nanotube carrier. 12 . The oxygen reduction catalyst according to claim 11 , wherein the loading amount of the catalytically active material on the carbon nanotube carrier is 0.1 wt % to 20 wt %. 13 . 13. The oxygen reduction catalyst according to claim 12, wherein the catalytically active material is derived from graphene, platinum, palladium, silver, yttrium oxide, ruthenium oxide, manganese dioxide, cobalt oxide, nickel cobaltate, Any one or a combination of two or more of nickel hydroxide, iron oxide, tungsten oxide, zinc oxide, titanium oxide, polyaniline, polypyrrole, polythiophene, polydopamine, and ammonia. 14. A preparation method of an oxygen reduction catalyst, characterized in that it comprises: providing the defective carbon nanotube carrier of claim 9, And, a catalytically active substance is supported on the carbon nanotube carrier to obtain the oxygen reduction catalyst. 15. The preparation method according to claim 14, characterized in that it comprises: using electrochemical deposition, electrophoretic deposition, hydrothermal, solvothermal, physical spraying, physical dipping, chemical vapor deposition, electric heating, atomic layer deposition, evaporation and The catalytically active material is supported on the carbon nanotube carrier by any one or a combination of two or more of the sputter deposition methods. 16. The preparation method according to claim 14, wherein the catalytically active material is derived from graphene, platinum, palladium, silver, yttrium oxide, ruthenium oxide, manganese dioxide, cobalt oxide, nickel cobaltate, Any one or a combination of two or more of nickel hydroxide, iron oxide, tungsten oxide, zinc oxide, titanium oxide, polyaniline, polypyrrole, polythiophene, polydopamine, and ammonia. 17. A fuel cell, characterized by comprising the deficient carbon nanotube carrier of claim 9 or the oxygen reduction catalyst of claim 11.

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