CN112038647B - A method based on COFs-derived carbon nanotubes to catalyze ORR reaction - Google Patents

Abstract

Translated fromChinese

本发明公开了一种基于COFs衍生纳米碳管催化ORR反应的方法，属于燃料电池阴极部分电催化氧还原领域。本发明所述的共价有机框架COFs衍生的纳米碳管在催化阴极氧还原反应中的应用，包括如下步骤：将共价有机框架COFs衍生的纳米碳管作为催化剂应用在阴极氧还原反应中，其中采用的纳米碳管由COFs衍生而来，规整可控的掺金属/杂原子或碳管直径与壁厚都有利于ORR活性的调控，具有良好的应用前景，而且采用溶剂热制备方法，既简单又安全。

The invention discloses a method for catalyzing ORR reaction based on COFs-derived carbon nanotubes, and belongs to the field of electrocatalytic oxygen reduction in the cathode part of a fuel cell. The application of the carbon nanotubes derived from the covalent organic framework COFs in catalyzing the cathode oxygen reduction reaction according to the present invention includes the following steps: using the carbon nanotubes derived from the covalent organic framework COFs as a catalyst in the cathode oxygen reduction reaction, The carbon nanotubes used are derived from COFs, and the regular and controllable metal/heteroatom or carbon tube diameter and wall thickness are conducive to the regulation of ORR activity, and have good application prospects, and the solvothermal preparation method is used. Simple and safe.

Description

Method for catalyzing ORR reaction based on COFs derived carbon nanotubes

Technical Field

The invention relates to a method for catalyzing ORR reaction based on COFs derived carbon nanotubes, belonging to the field of electrocatalytic oxygen reduction of a cathode part of a fuel cell.

Background

The conventional fossil fuel has failed to satisfy the demand of economic development in the world due to its limited reserves and a series of environmental problems caused by its utilization. People urgently need to change the use mode and structure of energy and develop a new energy utilization technology with high efficiency, economy and environmental protection. The fuel cell is a chemical device which can directly convert chemical energy of fuel (such as hydrogen, methanol and the like) and oxidant (such as oxygen and the like) into electric energy through electrochemical reaction, is efficient and pollution-free, and has wide prospects. However, the electrochemically kinetically retarded cathode Oxygen Reduction Reaction (ORR) greatly reduces the efficiency of the fuel cell. Currently, the most common catalyst for catalytic oxygen reduction processes is a Pt-based noble metal catalyst, and most commercial fuel cells use a Pt/C catalyst. However, Pt has disadvantages of low reserves and high price, so it is a key to find a catalyst with low price and high ORR performance, and thus non-noble metal/metal-free doped atomic carbon materials have attracted much attention.

Disclosure of Invention

In order to solve at least one of the above problems, the present invention aims to provide a method for catalyzing ORR reaction based on COFs-derived carbon nanotubes, wherein the method for preparing covalent organic framework-derived carbon nanotubes comprises: selecting a metal nanowire as a template, carrying out solvothermal reaction in a vacuum environment to grow COFs on the surface of the metal nanowire in situ, calcining the obtained composite material at high temperature in an inert gas atmosphere, and etching metal by using a nitric acid solution to obtain a carbon nanotube; the method has simple and ingenious process, and the prepared carbon material is regular and controllable and has considerable ORR activity.

The first purpose of the present invention is to provide a method for catalyzing ORR reaction based on COFs derived carbon nanotubes, comprising the following steps: carbon nanotubes derived from Covalent Organic Frameworks (COFs) are used as a catalyst to be applied to a cathode oxygen reduction reaction; the preparation method of the COFs-derived carbon nanotube comprises the following steps:

(1) selecting metal nanowires as templates, and growing COFs on the surfaces of the metal nanowires in situ through solvothermal reaction in a vacuum environment to obtain a composite material;

(2) placing the composite material obtained in the step (1) in a reaction vessel, and heating to 800-1000 ℃; then cooling to obtain a carbonized material; wherein, the whole process is under the protection of inert gas;

(3) and (3) placing the carbonized material obtained in the step (2) into a container for acid washing, and then filtering, washing and drying to obtain the COFs-derived carbon nanotube.

Optionally, the preparation method of the carbon nanotubes derived from COFs comprises:

(1) selecting metal nanowires as templates, and growing COFs on the surfaces of the metal nanowires in situ through solvothermal reaction in a vacuum environment to obtain a composite material;

(2) placing the composite material obtained in the step (1) in a reaction vessel, heating to 800-; then cooling to room temperature to obtain a carbonized material; wherein, the whole carbonization process is under the protection of inert gas;

(3) placing the carbonized material obtained in the step (2) into a reaction container, adding the prepared acid solution, and uniformly stirring; then filtering and washing to obtain the carbon nanotubes derived from the COFs.

Optionally, the carbon nanotubes derived from Covalent Organic Frameworks (COFs) are used as a catalyst for a cathodic oxygen reduction reaction, and specifically: dissolving carbon nanotubes derived from Covalent Organic Frameworks (COFs) as a catalyst in a solvent to obtain a catalyst solution; then modifying a glassy carbon electrode by adopting a catalyst solution to serve as a working electrode; and finally, applying the working electrode to the oxygen precipitation reaction in the catalytic electrolysis water.

Optionally, the thickness of the COFs layer is in the range of 1-5 nm.

Optionally, the concentration of the catalyst solution is 0.001-0.01mg/μ L, and more preferably 0.0058mg/μ L.

Optionally, the dosage of the catalyst solution is 10 mu L/0.1-0.2cm²More preferably 10. mu.L/0.192 cm²(ii) a I.e. 10. mu.l of catalyst solution droplets at an area of 0.192cm²A glassy carbon electrode.

Optionally, the solvent is a mixed solution of isopropanol solution and Nafion solution; wherein the volume ratio of the isopropanol to the water in the isopropanol solution is 3-5: 1; the mass fraction of the Nafion solution is 4-6%; the volume ratio of the isopropanol solution to the Nafion solution is 75-85: 5.

optionally, the solvent is a mixed solution of isopropanol solution and Nafion solution; wherein the volume ratio of isopropanol to water in the isopropanol solution is 3: 1; the mass fraction of the Nafion solution is 5 percent; the volume ratio of the isopropanol solution to the Nafion solution is 80: 5.

optionally, the carbon nanotubes derived from Covalent Organic Frameworks (COFs) can be used as a catalyst to catalyze a cathode oxygen reduction reaction, and further can be used for a methanol direct fuel cell and a zinc air fuel cell.

Optionally, the step (1) is:

adding metal nanowires and amino COFs monomers in a container according to a proportion, adding a mixed organic solvent, and uniformly mixing; then adding a catalyst, and continuously and uniformly mixing to obtain a mixed solution; dissolving aldehyde COFs monomers in a mixed solvent, and uniformly mixing to obtain an aldehyde COFs monomer solution; then dripping the aldehyde COFs monomer solution into the mixed solution, uniformly mixing, and then carrying out in-situ growth reaction; then washing, centrifuging and drying; thus obtaining the composite material.

Optionally, the step (1) specifically comprises:

adding metal nanowires and amino COFs monomers in a reaction container according to a ratio, adding a mixed organic solvent, and ultrasonically mixing uniformly; then adding a catalyst, and continuously and uniformly mixing by ultrasonic waves to obtain a mixed solution; dissolving aldehyde COFs monomers in a mixed solvent, and uniformly mixing by ultrasonic waves to obtain an aldehyde COFs monomer solution; then, dripping the aldehyde COFs monomer solution into the mixed solution, and continuing ultrasonic mixing to obtain a composite material mixed solution; then transferring the composite material mixed solution into a Pyrex bottle, and placing the Pyrex bottle for reaction after repeated freezing-vacuumizing-dissolving cycles; then washing, centrifuging and drying; thus obtaining the composite material.

Optionally, the freezing in the step (1) is to freeze liquid by using liquid nitrogen, and the vacuumizing is to vacuumize by using a double-row pipe; the dissolution is that the temperature is raised to the room temperature, and the frozen reaction mixture is dissolved again; the number of repeated freezing-vacuumizing-dissolving cycles in the step (1) is 3.

Optionally, the reaction conditions after the repeated freezing-vacuumizing-dissolving cycles in the step (1) are as follows: placing the mixture in an oven at 90-130 ℃ for reaction for 60-80 h.

Optionally, the washing in the step (1) is performed 3 to 5 times by using a cyclohexane/methanol mixed solution.

Optionally, the metal nanowire in step (1) is one or both of a copper nanowire and a silver nanowire, and the diameter of the metal nanowire is 15-200 nm.

Optionally, the diameter of the metal nanowire in the step (1) is in the range of 20-50 nm.

Optionally, the amino COFs monomer in step (1) is one or two of 5,10,15, 20-tetrakis (4-aminophenyl) porphyrin and 5,5 '-diamino-2, 2' -bipyridine.

Optionally, the aldehyde COFs monomer in step (1) is one or two of terephthalaldehyde and trialdehyde phloroglucinol.

Optionally, the mass ratio of the metal nanowire and the theoretically formed COFs in the step (1) is 15: 1-1: 2.

optionally, the proportion of the amino-aldehyde is different for different COFs, depending on the number of the amino-aldehyde functional groups on the monomer and the molecular weight, specifically, one molar equivalent of aldehyde group corresponds to one molar equivalent of amino group.

Optionally, the mixed organic solvent in the step (1) is ethanol/mesitylene, and the volume ratio of the ethanol to the mesitylene is 2:1-1: 2.

Optionally, the mass-to-volume ratio of the metal nanowires to the mixed organic solvent in the mixed solution in the step (1) is 2-15mg/mL, that is, 2-15mg of the metal nanowires are added into 1mL of the mixed organic solvent.

Optionally, the ultrasound parameters in step (1) are set as: the ultrasonic power is 200W, and the ultrasonic time is 30-70 min.

Optionally, the catalyst in the step (1) is a schiff base reaction acidic catalyst, specifically an acetic acid solution, and the concentration of the acetic acid solution is 3-6M.

Optionally, the adding amount of the catalyst in the step (1) is 5-20% of the volume of the mixed organic solvent.

Optionally, the mass-to-volume ratio of the amino COFs monomer in the step (1) to the mixed organic solvent is 0.5-20 mg/mL.

Optionally, the mass-to-volume ratio of the aldehyde COFs monomers to the mixed solvent in step (1) is 0.5-20mg/mL, that is, 0.5-20mg of the aldehyde COFs monomers are dissolved in 1mL of the mixed solvent.

Optionally, the mixing time of the mixed solution in the step (1) is 15-40min, the mixing time of the aldehyde COFs monomer solution is 10-20min, and the mixing time of the composite material solution is 20-40 min.

Optionally, the drying in step (1) is vacuum drying, and the specific parameters are as follows: the temperature is 60-80 ℃ and the time is 8-12 h.

Optionally, the temperature rise rate in the step (2) is 2-5 ℃/min.

Optionally, the inert gas in the step (2) is argon.

Optionally, the step (3) specifically includes: placing the carbonized material obtained in the step (2) into a reaction container, adding a prepared acid solution, uniformly stirring, filtering by using a microfiltration membrane, and repeatedly washing by using water until the filtrate is neutral; finally, vacuum drying is carried out overnight, and the carbon nanotubes derived from the COFs are obtained.

Optionally, the concentration of the acid solution in the step (3) is 8-15M.

Optionally, the strong acid solution in the step (3) is a nitric acid solution.

Optionally, the mass-to-volume ratio of the carbonized material to the acid solution in the step (3) is 0.2-1mg/mL, that is, 0.2-1mg of carbonized material is added to 1mL of acid solution.

Optionally, the stirring speed in the step (3) is 400-1000 rpm; stirring for 16-32 h; sonication can be performed prior to agitation.

Optionally, the microfiltration membrane in the step (3) is a water-based microfiltration membrane, and the specific parameters are as follows: the diameter of the hole is 50mm and the hole diameter is 0.22 μm.

Optionally, the vacuum drying parameters in step (3) are as follows: the temperature is 60-80 ℃.

The second purpose of the invention is to provide a method for catalyzing ORR reaction based on COFs derived metal-doped carbon nanotubes, which comprises the following steps: applying COFs-derived metal-doped carbon nanotubes as a catalyst in a cathode oxygen reduction reaction; the preparation method of the COFs-derived metal-doped carbon nanotube is that metal doping can be carried out before the step (2) of the preparation method of the carbon nanotube derived from the covalent organic framework, and specifically comprises the following steps:

(1) selecting metal nanowires as templates, and growing COFs on the surfaces of the metal nanowires in situ through solvothermal reaction in a vacuum environment to obtain a composite material;

(2) placing the composite material obtained in the step (1) in a reaction container, adding doped transition metal salt and an organic solvent, uniformly mixing, reacting at 75-90 ℃, and then cooling, washing and drying to obtain powder;

(3) putting the powder obtained in the step (2) into a reaction container, and heating to 800-1000 ℃; then cooling to obtain a carbonized material; wherein, the whole process is under the protection of inert gas;

(4) and (4) placing the carbonized material obtained in the step (3) into a reaction vessel, carrying out acid washing, and then filtering and washing to obtain the COFs-derived metal-doped carbon nanotube.

Optionally, the preparation method of the COFs derived metal-doped carbon nanotube comprises:

(1) selecting metal nanowires as templates, and growing COFs on the surfaces of the metal nanowires in situ through solvothermal reaction in a vacuum environment to obtain a composite material;

(2) placing the composite material obtained in the step (1) in a reaction vessel, adding doped transition metal salt and an organic solvent, uniformly mixing, heating to 75-90 ℃ in an oil bath, stirring, and keeping condensation and reflux for 6-10 h; cooling to room temperature, washing and drying to obtain powder;

(3) placing the powder obtained in the step (2) in a porcelain boat, heating to 800-; then cooling to room temperature to obtain a carbonized material; wherein, the whole carbonization process is under the protection of inert gas;

(4) placing the carbonized material obtained in the step (3) in a glass bottle, adding the prepared acid solution, and uniformly stirring; and then filtering and washing to obtain the COFs-derived metal-doped carbon nanotube.

Optionally, the doped transition metal salt in the step (2) is one or more of acetate, chloride, nitrate and acetylacetone.

Optionally, the organic solvent in step (2) is methanol.

Optionally, the mass ratio of the composite material, the doped metal and the organic solvent in the step (2) is 1: (0.5-5): (1-3.5).

Optionally, the organic solvent in step (2) is methanol.

Optionally, the washing in step (2) is 3-5 times with a cyclohexane/methanol mixed solution.

Optionally, the drying in step (2) is carried out in a vacuum oven at 60-80 ℃ overnight.

The invention has the beneficial effects that:

(1) the carbon nanotube material derived from COFs without metal doping can obtain higher limiting current density (5.8 mA/cm) in the oxidation-reduction reaction of the catalytic cathode²) And half-wave potential (0.81V vs. rhe).

(2) The carbon nanotube material derived from COFs doped with metal can obtain higher limiting current density (5.4 mA/cm) in the oxidation-reduction reaction of the catalytic cathode²) And half-wave potential (0.8V vs. rhe).

(3) The invention can flexibly regulate and control the inner diameter and the tube wall thickness of the carbon nano-tube by controlling the diameter of the silver nano-wire in the precursor COF @ Ag and the thickness of the COFs layer, thereby influencing the ORR activity expression of the carbon nano-tube.

Drawings

FIG. 1 is a graph showing oxygen reduction polarization curves of porphyrin-based COFs-CNT of example 1 and pyridine-based COFs-CNT of example 2 at 0.1M KOH.

FIG. 2 is a scanning electron micrograph of carbon nanotubes derived from porphyrin-based COFs in example 1.

FIG. 3 is a photograph showing the elemental analysis of carbon nanotubes derived from porphyrins COFs in example 1, wherein (a) is an original drawing; (b) is a photograph of element C; (c) is an N element photograph.

FIG. 4 is a scanning electron micrograph of carbon nanotubes derived from pyridine COFs in example 2.

FIG. 5 is an oxygen reduction polarization curve of porphyrin-based COFs-CoCNT of example 3 and pyridine-based COFs-FeCNT of example 4 at 0.1M KOH.

FIG. 6 is a microscopic morphology of porphyrin COF-Co derived cobalt-doped carbon nanotubes in example 3; (a) scanning an electron microscope picture; (b) and (5) transmission electron microscope photographs.

FIG. 7 is a microscopic morphology of the pyridine COFs-Fe-derived Fe-doped carbon nanotubes of example 4; (a) scanning an electron microscope picture; (b) and (5) transmission electron microscope photographs.

FIG. 8 shows the effect of COFs-derived carbon nanotubes solid powder with covalent organic frameworks on the electrocatalytic oxygen reduction activity.

Fig. 9 shows the effect of covalent organic framework COFs-derived carbon nanotube solid powders on electrocatalytic oxygen reduction activity at different calcination temperatures.

Detailed Description

The following description of the preferred embodiments of the present invention is provided for the purpose of better illustrating the invention and is not intended to limit the invention thereto.

Example 1

The application of carbon nanotubes derived from Covalent Organic Frameworks (COFs) in catalyzing cathode oxygen reduction reaction comprises the following steps: carbon nanotubes derived from Covalent Organic Frameworks (COFs) are used as a catalyst to be applied to a cathode oxygen reduction reaction; the method specifically comprises the following steps: weighing 0.5mg of carbon nanotube solid powder derived from Covalent Organic Frameworks (COFs) and adding the carbon nanotube solid powder into a mixed solution of 80 microliters of isopropanol aqueous solution (the volume ratio of isopropanol to water is 3:1) and 5 microliters of perfluorosulfonic acid Nafion solution (mass fraction is 5%), and carrying out ultrasonic homogenization; then, 10. mu.l was dropped and applied to an area of 0.192cm²Obtaining a working electrode on the glassy carbon electrode; and finally, applying the working electrode to the oxygen precipitation reaction in the catalytic electrolysis water.

The specific catalytic cathodic oxygen reduction reaction test is to place the working electrode in 0.1M potassium hydroxide solution to test the electrocatalytic oxygen reduction activity, and the obtained data are shown in figure 1.

The preparation method of the carbon nanotube derived from the covalent organic framework comprises the following steps:

(1) putting 12mg of silver nanowires (the diameter is 20nm) and 3mg of 5,10,15, 20-tetra (4-aminophenyl) porphyrin into a glass bottle, adding a mixed solution of 2mL of ethanol/mesitylene (the volume ratio is 1:1), ultrasonically mixing for 30 minutes, adding 0.2mL of 3M acetic acid solution, and continuously ultrasonically mixing for 5 minutes to obtain a mixed solution; dissolving 1.2mg of terephthalaldehyde in 400 microliters of ethanol/mesitylene (volume ratio is 1:1) mixed solution, and uniformly performing ultrasonic treatment to obtain a terephthalaldehyde solution; slowly dripping the terephthalaldehyde solution into the mixed solution, and continuing to perform ultrasonic treatment for 20 minutes to obtain a composite material solution; then transferring the composite material solution into a Pyrex glass bottle, performing three freezing-vacuumizing-dissolving processes by using liquid nitrogen and a double-row pipe device, and finally placing the glass bottle in a 95 ℃ oven to react for 72 hours under the condition of keeping a vacuumizing state; after the reaction, washing the solution with cyclohexane/methanol mixed solution for 5 times, and drying the solution in a vacuum oven at 80 ℃ overnight to obtain COF @ Ag powder.

(2) Placing the COF @ Ag powder obtained in the step (1) in a porcelain boat, heating to 1000 ℃ at a speed of 5 ℃/min in an argon atmosphere by using a tube furnace, then preserving heat for 3h, and cooling to room temperature under the protection of inert gas to obtain a carbonized material;

(3) placing the carbonized material (14.5mg) obtained in the step (2) into a glass bottle, adding the prepared 30mL of 8M nitric acid solution, ultrasonically homogenizing, stirring (the stirring speed is 800rpm) for 24h, performing suction filtration by using a water-based microfiltration membrane (the parameter of the filtration membrane is that the diameter is 50mm, and the pore diameter is 0.22 mu M), and repeatedly washing by using water until the filtrate is neutral; finally, vacuum drying (temperature is 80 ℃) overnight to obtain the porphyrin COFs-CNT, wherein the surface appearance of the porphyrin COFs-CNT is shown in FIG. 2, and can be seen from FIG. 2: the porphyrin COFs-CNT has uniform tubular structure and the outer diameter of the tube is controlled to be about 40 nm; the surface element analysis is shown in fig. 3, and it can be seen from fig. 3 that: the porphyrin COFs-CNT is composed of C and N elements and is essentially different from a carbon nano tube composed of pure C.

Example 2

An application of carbon nanotubes derived from Covalent Organic Frameworks (COFs) in catalyzing cathode oxygen reduction reaction comprises the following steps: carbon nanotubes derived from Covalent Organic Frameworks (COFs) are used as a catalyst to be applied to a cathode oxygen reduction reaction; the method specifically comprises the following steps: weighing 0.5mg of carbon nanotube solid powder derived from Covalent Organic Frameworks (COFs) and adding the carbon nanotube solid powder into a mixed solution of 80 microliters of isopropanol aqueous solution (the volume ratio of isopropanol to water is 3:1) and 5 microliters of perfluorosulfonic acid Nafion solution (mass fraction is 5%), and carrying out ultrasonic homogenization; then, 10. mu.l was dropped and applied to an area of 0.192cm²Obtaining a working electrode on the glassy carbon electrode; and finally, applying the working electrode to the oxygen precipitation reaction in the catalytic electrolysis water. The specific catalytic cathodic oxygen reduction reaction test is to place the working electrode in 0.1M potassium hydroxide solution to test the electrocatalytic oxygen reduction activity, and the obtained data are shown in figure 1.

The preparation method of the carbon nanotube derived from the covalent organic framework comprises the following steps:

(1) putting 12mg of silver nanowires (the diameter is 30nm) and 2.4mg of 5,5 '-diamino-2, 2' -bipyridine into a glass bottle, adding a mixed solution of 2mL of ethanol/mesitylene (the volume ratio is 1:1), ultrasonically mixing for 30 minutes, adding 0.2mL of 3M acetic acid solution, and continuously ultrasonically mixing for 5 minutes to obtain a mixed solution; dissolving 1.8mg of trialdehyde phloroglucinol into 400 microliters of mixed solution of ethanol/mesitylene (volume ratio is 1:1) and performing ultrasonic homogenization to obtain trialdehyde phloroglucinol solution; slowly dripping the p-trialdehyde phloroglucinol solution into the mixed solution, and continuing to perform ultrasonic treatment for 20 minutes to obtain a composite material solution; then transferring the composite material solution into a Pyrex glass bottle, and performing three freezing-vacuumizing-dissolving processes by using liquid nitrogen and a double-row pipe device; finally, placing the mixture in a 95 ℃ oven to react for 72 hours under the condition of keeping the vacuumizing state; after the reaction, washing the solution with cyclohexane/methanol mixed solution for 5 times, and drying the solution in a vacuum oven at 80 ℃ overnight to obtain COF @ Ag powder.

(2) Placing the COF @ Ag powder obtained in the step (1) in a porcelain boat, heating to 1000 ℃ at a speed of 5 ℃/min in an argon atmosphere by using a tube furnace, then preserving heat for 3h, and cooling to room temperature under the protection of inert gas to obtain a carbonized material;

(3) placing the carbonized material (15mg) obtained in the step (2) into a glass bottle, adding the prepared 30mL of 8M nitric acid solution, ultrasonically homogenizing, stirring (the stirring speed is 800rpm) for 24h, performing suction filtration by using a water-based microfiltration membrane (the parameter of the filtration membrane is that the diameter is 50mm, and the aperture is 0.22 mu M), and repeatedly washing by using water until the filtrate is neutral; finally, vacuum drying (temperature 80 ℃) is carried out overnight, thus obtaining the pyridine COFs-CNT, the appearance of which is shown in FIG. 4, and can be seen from FIG. 4: the pyridine COFs-CNT is regular and uniform in tubular structure.

Example 3

An application of carbon nanotubes derived from Covalent Organic Frameworks (COFs) in catalyzing cathode oxygen reduction reaction comprises the following steps: carbon nanotubes derived from Covalent Organic Frameworks (COFs) are used as a catalyst to be applied to a cathode oxygen reduction reaction; the method specifically comprises the following steps: weighing 0.5mg of carbon nanotube solid powder derived from Covalent Organic Frameworks (COFs) and adding the carbon nanotube solid powder into a mixed solution of 80 microliters of isopropanol aqueous solution (the volume ratio of isopropanol to water is 3:1) and 5 microliters of perfluorosulfonic acid Nafion solution (mass fraction is 5%), and carrying out ultrasonic homogenization; then, 10. mu.l was dropped and applied to an area of 0.192cm²Obtaining a working electrode on the glassy carbon electrode; finally, the working electrode is applied to the catalystAnd (4) carrying out oxygen precipitation reaction in the electrolyzed water. The specific catalytic cathodic oxygen reduction reaction test is to place the working electrode in 0.1M potassium hydroxide solution to test the electrocatalytic oxygen reduction activity, and the obtained data are shown in figure 5.

The preparation method of the carbon nanotube derived from the covalent organic framework comprises the following steps:

(1) putting 12mg of silver nanowires (the diameter is 40nm) and 3mg of 5,10,15, 20-tetra (4-aminophenyl) porphyrin into a glass bottle, adding a mixed solution of 2mL of ethanol/mesitylene (the volume ratio is 1:1), ultrasonically mixing for 30 minutes (the ultrasonic power is 200W), adding 0.2mL of 3M acetic acid solution, and continuously ultrasonically treating for 5 minutes to obtain a mixed solution; dissolving 1.2mg of terephthalaldehyde in 400 microliters of ethanol/mesitylene (volume ratio is 1:1) mixed solution, and uniformly performing ultrasonic treatment to obtain a terephthalaldehyde solution; slowly dripping the terephthalaldehyde solution into the mixed solution, and continuing to perform ultrasonic treatment for 20 minutes to obtain a composite material solution; then transferring the composite material solution into a Pyrex glass bottle, and performing three freezing-vacuumizing-dissolving processes by using liquid nitrogen and a double-row pipe device; finally, the mixture is placed in an oven at 95 ℃ for reaction for 72 hours under the condition of keeping the vacuumizing state. After the reaction, washing the solution with cyclohexane/methanol mixed solution for 5 times, and drying the solution in a vacuum oven at 80 ℃ overnight to obtain COF @ Ag powder.

(2) Placing the COF @ Ag powder (15.6mg) obtained in the step (1) into a 50mL round-bottom flask, adding 5mg of cobalt acetate and 20mL of methanol, uniformly mixing, heating to 80 ℃ in an oil bath, stirring, and keeping condensation reflux for 8 hours; cooling to room temperature, washing with cyclohexane/methanol mixed solution for 3 times, and drying in a vacuum oven at 80 deg.C overnight to obtain powder;

(3) placing the powder obtained in the step (2) in a porcelain boat, heating to 900 ℃ at the speed of 5 ℃/min in an argon atmosphere by using a tube furnace, then preserving heat for 3h, and cooling to room temperature under the protection of inert gas to obtain a carbonized material;

(4) placing the carbonized material (15.2mg) obtained in the step (3) into a glass bottle, adding the prepared 30mL of 8M nitric acid solution, ultrasonically homogenizing, stirring (the stirring speed is 700rpm) for 24h, performing suction filtration by using a water-based microfiltration membrane (the parameter of the filtration membrane is that the diameter is 50mm, and the pore diameter is 0.22 mu M), and repeatedly washing by using water until the filtrate is neutral; finally, vacuum drying (temperature is 80 ℃) overnight to obtain the porphyrin COFs-CoCNT, wherein the appearance of the porphyrin COFs-CoCNT is shown in FIG. 6, and can be seen from FIG. 6: porphyrin class COFs-CoCNT combines cobalt ions by utilizing the N coordination of porphyrin and is reduced at high temperature to form a metal-doped carbon nanotube; no metal particles are observed in the transmission electron microscope, visible metal silver or cobalt particles are completely removed, and the tubular structure of the carbon nanotube is regular and uniform.

Example 4

An application of carbon nanotubes derived from Covalent Organic Frameworks (COFs) in catalyzing cathode oxygen reduction reaction comprises the following steps: the method specifically comprises the following steps: carbon nanotubes derived from Covalent Organic Frameworks (COFs) are used as a catalyst to be applied to a cathode oxygen reduction reaction; the method specifically comprises the following steps: weighing 0.5mg of carbon nanotube solid powder derived from Covalent Organic Frameworks (COFs) and adding the carbon nanotube solid powder into a mixed solution of 80 microliters of isopropanol aqueous solution (the volume ratio of isopropanol to water is 3:1) and 5 microliters of perfluorosulfonic acid Nafion solution (mass fraction is 5%), and carrying out ultrasonic homogenization; then, 10. mu.l was dropped and applied to an area of 0.192cm²Obtaining a working electrode on the glassy carbon electrode; and finally, applying the working electrode to the oxygen precipitation reaction in the catalytic electrolysis water. The specific catalytic cathodic oxygen reduction reaction test is to place the working electrode in 0.1M potassium hydroxide solution to test the electrocatalytic oxygen reduction activity, and the obtained data are shown in figure 5.

The preparation method of the carbon nanotube derived from the covalent organic framework comprises the following steps:

(1) putting 12mg of silver nanowires (the diameter is 20nm) and 2.4mg of 5,5 '-diamino-2, 2' -bipyridine into a glass bottle, adding a mixed solution of 2mL of ethanol/mesitylene (the volume ratio is 1:1), ultrasonically mixing for 30 minutes (the ultrasonic power is 200W), adding 0.2mL of 3M acetic acid solution, and continuously ultrasonically treating for 5 minutes to obtain a mixed solution; dissolving 1.8mg of trialdehyde phloroglucinol into 400 microliters of mixed solution of ethanol/mesitylene (volume ratio is 1:1) and performing ultrasonic homogenization to obtain trialdehyde phloroglucinol solution; slowly dripping the trialdehyde phloroglucinol solution into the mixed solution, and continuing to perform ultrasonic treatment for 20 minutes to obtain a composite material solution; then transferring the composite material solution into a Pyrex glass bottle, performing three freezing-vacuumizing-dissolving processes by using liquid nitrogen and a double-row pipe device, and finally placing the glass bottle in a 95 ℃ oven to react for 72 hours under the condition of keeping a vacuumizing state; after the reaction is finished, washing the reaction product for 5 times by using a cyclohexane/methanol mixed solution, and drying the reaction product in a vacuum oven at 80 ℃ overnight to obtain COF @ Ag powder;

(2) placing the COF @ Ag powder (15.8mg) obtained in the step (1) into a 50mL round-bottom flask, adding 5mg of ferric chloride and 20mL of methanol, uniformly mixing, heating to 80 ℃ in an oil bath, stirring, and keeping the mixture under condensation reflux for 8 hours; cooling to room temperature, washing with cyclohexane/methanol mixed solution for 3 times, and drying in a vacuum oven at 80 deg.C overnight to obtain powder;

(3) placing the powder obtained in the step (2) in a porcelain boat, heating to 900 ℃ at the speed of 5 ℃/min in an argon atmosphere by using a tube furnace, then preserving heat for 3h, and cooling to room temperature under the protection of inert gas to obtain a carbonized material;

(4) and (3) placing the carbonized material (15.4mg) obtained in the step (3) into a glass bottle, adding the prepared 30mL of 8M nitric acid solution, performing ultrasonic homogenization, stirring at the stirring speed of 700rpm for 24 hours, performing suction filtration by using a water-based microfiltration membrane (the parameter of the filtration membrane is that the diameter is 50mm, and the pore diameter is 0.22 mu M), and repeatedly washing by using water until the filtrate is neutral. Finally, vacuum drying (the temperature is 80 ℃) overnight to obtain the pyridine COFs-FeCNT, wherein the appearance of the pyridine COFs-FeCNT is shown in FIG. 7, and can be seen from FIG. 7: pyridine COFs-FeCNT combines iron ions by utilizing the N coordination of pyridine and is reduced at high temperature to form a metal-doped carbon nanotube; clear tubular structures can be observed, the inner diameter of the tube is 30nm, and the wall thickness is 1-5 nm. .

Fig. 1 and 5 are graphs of oxygen reduction performance of porphyrin-based COFs and pyridine-based COFs derived carbon nanotubes without metal-doped N series and with metal-doped N series, respectively. The data in the figure are polarization curves tested in 0.1M KOH solution by a rotating disk electrode device at a rotation rate of 1600rpm/min, and the ORR activity of the catalyst can be preliminarily judged by the limiting current and the half-wave potential (generally, the larger the limiting current or the larger the half-wave potential, the better the performance). As can be seen from fig. 1: the limiting current density of the porphyrin COFs-CNT as the catalyst in the catalytic cathodic oxygen reduction of example 1 reaches 5.1mA/cm²) The half-wave potential reaches 0.77V vs. RHE; the pyridine COFs-CNT of example 2 is used as a catalyst to achieve the limiting current density in the catalytic cathodic oxygen reduction5.4mA/cm²) The half-wave potential reaches 0.81V vs. RHE; as can be seen from fig. 5: the limiting current density of the porphyrin COFs-CoCNT serving as the catalyst in the catalytic cathodic oxygen reduction of example 3 reaches 5mA/cm²The half-wave potential reaches 0.79V vs. RHE; the limiting current density of the pyridine COFs-FeCNT serving as a catalyst in catalytic cathodic oxygen reduction of example 4 reaches 5.4mA/cm²The half-wave potential reaches 0.8V vs. rhe. As can be seen from fig. 1 and 5: even without metal, the metal-free conductive coating still has large limiting current and considerable half-wave potential.

Example 5

The mass ratio of silver nanowires to COFs monomer charge (5,10,15, 20-tetrakis (4-aminophenyl) porphyrin) in example 1 was adjusted to be shown in Table 1, wherein the number is the mass ratio of silver nanowires to COFs monomer charge (5,10,15, 20-tetrakis (4-aminophenyl) porphyrin), and other parameters and example 1 were kept unchanged, and the electrocatalytic oxygen reduction activity was detected. The results are shown in table 1 and fig. 8:

TABLE 1 influence of composite-derived carbon nanotube solid powder on electrocatalytic oxygen reduction activity, obtained from different mass ratios of silver nanowires to COFs monomer charge

From the polarization curve of fig. 8, the obtained half-wave potential and limiting current density are summarized in table 1. As can be seen from table 1: the catalytic performance of the carbon nanotube derived from the composite material can be optimized by changing the mass ratio of the silver nanowire to the COFs monomer, wherein when the mass ratio of the silver nanowire to the COFs monomer is 3, the maximum half-wave potential of 0.78V can be obtained, and when the mass ratio of the silver nanowire to the COFs monomer is 2 or 4, the maximum limiting current of 5.1mA/cm can be obtained²。

Example 6

The electrocatalytic oxygen reduction activity was measured by adjusting the calcination temperature in example 1 to the value shown in Table 2, while keeping the other parameters and example 1. The results are shown in table 2 and fig. 9:

TABLE 2 influence of covalent organic frameworks COFs derived carbon nanotubes solid powders of different calcination temperatures on the electrocatalytic oxygen reduction activity

From the polarization curve of fig. 9, the obtained half-wave potential and limiting current density are summarized in table 2. As can be seen from table 2: the catalytic performance of the carbon nanotube derived from the composite material can be optimized by changing the calcination temperature, wherein when the calcination temperature is 900 ℃, the obtained carbon nanotube can obtain the maximum half-wave potential and the maximum limiting current which are respectively 0.81V and 5.8mA/cm²。

Example 7 diameter optimization of nanowires

The diameter of the nano silver of example 2 was adjusted to be as shown in table 3, and the electrocatalytic oxygen reduction activity was measured while keeping other parameters and example 2. The results are shown in table 3:

TABLE 3 influence of carbon nanotube solid powder derived from different nanosilver diameter composites on electrocatalytic oxygen reduction activity

As can be seen from table 3: the diameter of the silver nanowire can optimize the catalytic performance of the carbon nanotube derived from the composite material, wherein when the diameter of the silver nanowire is 30nm, the obtained carbon nanotube can obtain the maximum half-wave potential and the maximum limiting current which are respectively 0.81V and 5.4mA/cm²。

Comparative example 1

The carbon nanotubes derived from covalent organic frameworks COFs of example 1 were modified to commercial Pt/C catalysts (20%, Alfa Aesar), otherwise in agreement with example 1, and the catalytic performance was tested as shown in Table 4:

table 4 effect of the catalysts of example 1 and comparative example 1 on the electrocatalytic oxygen reduction activity

As can be seen from table 4: the catalytic performance of the obtained carbon nano-tube is close to that of a commercial Pt/C catalyst, and the limiting current density can even exceed that of the commercial Pt/C catalyst.

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

Translated fromChinese

1.一种基于COFs衍生纳米碳管催化ORR反应的方法，其特征在于，包括如下步骤：将共价有机框架COFs衍生纳米碳管作为催化剂应用在阴极氧还原ORR反应中；其中所述的COFs衍生纳米碳管的制备方法为：1. a method for catalyzing ORR reaction based on COFs-derived carbon nanotubes, is characterized in that, comprising the steps: using covalent organic framework COFs-derived carbon nanotubes as a catalyst in the cathode oxygen reduction ORR reaction; wherein the COFs The preparation method of the derived carbon nanotubes is as follows:(1)选择金属纳米线作为模板，真空环境下通过溶剂热反应在其表面原位生长COFs，得到复合材料；(1) Select metal nanowires as templates, and in situ grow COFs on their surfaces by solvothermal reaction in a vacuum environment to obtain composite materials;(2)将步骤(1)得到的复合材料置于反应容器中，升温至800-1000℃；之后冷却得到碳化材料；其中，整个过程都处于惰性气体保护下；(2) placing the composite material obtained in step (1) in a reaction vessel, and heating up to 800-1000 ° C; then cooling to obtain a carbonized material; wherein, the whole process is under the protection of inert gas;(3)将步骤(2)得到的碳化材料置于容器中进行酸洗，之后经过过滤、洗涤、干燥得到COFs衍生纳米碳管。(3) placing the carbonized material obtained in step (2) in a container for pickling, and then filtering, washing and drying to obtain COFs-derived carbon nanotubes.2.根据权利要求1所述的方法，其特征在于，所述的将共价有机框架COFs衍生的纳米碳管作为催化剂应用在阴极氧还原ORR反应中，具体是：将共价有机框架COFs衍生的纳米碳管作为催化剂，溶解在溶剂中得到催化剂溶液；之后采用催化剂溶液修饰玻碳电极作为工作电极；最后将工作电极应用在催化电解水中的氧析出反应即可。2. The method according to claim 1, wherein the carbon nanotubes derived from covalent organic framework COFs are used as catalysts in the cathodic oxygen reduction ORR reaction, specifically: derivatizing covalent organic framework COFs The prepared carbon nanotubes are used as catalysts and dissolved in a solvent to obtain a catalyst solution; then the glassy carbon electrode is modified with the catalyst solution as a working electrode; finally, the working electrode is applied to catalyze the oxygen evolution reaction in electrolyzed water.3.根据权利要求2所述的方法，其特征在于，所述的催化剂溶液的浓度为0.001-0.01mg/μL。3. The method according to claim 2, wherein the concentration of the catalyst solution is 0.001-0.01 mg/μL.4.根据权利要求2所述的方法，其特征在于，所述的催化剂溶液的用量为10μL/0.1-0.2cm²。4. The method according to claim 2, wherein the amount of the catalyst solution is 10 μL/0.1-0.2 cm² .5.根据权利要求2所述的方法，其特征在于，所述的溶剂为异丙醇溶液和Nafion溶液的混合溶液；其中异丙醇溶液中异丙醇与水的体积比＝3-5:1；Nafion溶液的质量分数为4-6％；异丙醇溶液与Nafion溶液的体积比为75-85：5。5. method according to claim 2, is characterized in that, described solvent is the mixed solution of Virahol solution and Nafion solution; Wherein in Virahol solution, the volume ratio of Virahol and water=3-5: 1; the mass fraction of Nafion solution is 4-6%; the volume ratio of isopropanol solution to Nafion solution is 75-85:5.6.根据权利要求1所述的方法，其特征在于，所述的步骤(1)具体为：6. method according to claim 1, is characterized in that, described step (1) is specifically:在容器中加入金属纳米线和氨基类COFs单体，并加入混合有机溶剂，混合均匀；之后加入催化剂，继续混合均匀，得到混合溶液；将醛类COFs单体溶解在混合溶剂中，混合均匀，得到醛类COFs单体溶液；之后将醛类COFs单体溶液滴加于混合溶液中，混合均匀，再进行原位生长反应；之后洗涤、离心、干燥；即得到复合材料。Add metal nanowires and amino-based COFs monomers into the container, add mixed organic solvent, and mix evenly; then add catalyst and continue to mix evenly to obtain a mixed solution; dissolve aldehyde-based COFs monomers in the mixed solvent, mix evenly, The aldehyde-based COFs monomer solution is obtained; then the aldehyde-based COFs monomer solution is added dropwise to the mixed solution, mixed uniformly, and then subjected to an in-situ growth reaction; and then washed, centrifuged, and dried to obtain a composite material.7.根据权利要求6所述的方法，其特征在于，步骤(1)所述的金属纳米线为铜纳米线、银纳米线中的一种；金属纳米线的直径在15-200nm；步骤(1)所述的混合溶液中金属纳米线和混合有机溶剂的质量体积比为2-15mg/mL。7. The method according to claim 6, wherein the metal nanowires in step (1) are one of copper nanowires and silver nanowires; the diameter of the metal nanowires is 15-200 nm; step ( 1) The mass-volume ratio of the metal nanowires and the mixed organic solvent in the mixed solution is 2-15 mg/mL.8.一种基于COFs衍生掺金属纳米碳管催化ORR反应的方法，其特征在于，包括如下步骤：将COFs衍生掺金属纳米碳管作为催化剂应用在阴极氧还原反应中；其中所述的COFs衍生掺金属纳米碳管的制备方法为共价有机框架衍生的纳米碳管的制备方法的步骤(2)中进行金属的掺杂，具体为：8. A method for catalyzing ORR reaction based on COFs-derived metal-doped carbon nanotubes, comprising the steps of: using COFs-derived metal-doped carbon nanotubes as a catalyst in a cathode oxygen reduction reaction; wherein the COFs-derived metal-doped carbon nanotubes are used in a cathode oxygen reduction reaction; The preparation method of metal-doped carbon nanotubes is to perform metal doping in step (2) of the preparation method of covalent organic framework-derived carbon nanotubes, specifically:(1)选择金属纳米线作为模板，真空环境下通过溶剂热反应在其表面原位生长COFs，得到复合材料；(1) Select metal nanowires as templates, and in situ grow COFs on their surfaces by solvothermal reaction in a vacuum environment to obtain composite materials;(2)将步骤(1)得到的复合材料置于反应容器中，加入掺杂过渡金属盐和有机溶剂混合均匀，75-90℃反应，之后冷却、洗涤、干燥，得到粉末；(2) placing the composite material obtained in step (1) in a reaction vessel, adding a doped transition metal salt and an organic solvent and mixing uniformly, reacting at 75-90° C., then cooling, washing and drying to obtain powder;(3)将步骤(2)得到的粉末置于瓷舟中，升温至800-1000℃；之后冷却，得到碳化材料；其中，整个过程都处于惰性气体保护下；(3) placing the powder obtained in step (2) in a porcelain boat, heating up to 800-1000 ° C; then cooling to obtain a carbonized material; wherein, the whole process is under the protection of inert gas;(4)将步骤(3)得到的碳化材料置于反应容器中，进行酸洗，之后经过过滤、洗涤得到COFs衍生掺金属纳米碳管。(4) The carbonized material obtained in step (3) is placed in a reaction vessel, acid-washed, and then filtered and washed to obtain COFs-derived metal-doped carbon nanotubes.9.根据权利要求8所述的方法，其特征在于，步骤(2)所述的掺杂过渡金属盐为乙酸盐、氯化盐、硝酸盐、乙酰丙酮盐中的一种或几种。9 . The method according to claim 8 , wherein the doped transition metal salt in step (2) is one or more of acetate, chloride, nitrate and acetylacetonate. 10 .10.根据权利要求8所述的方法，其特征在于，步骤(2)所述的复合材料、掺杂金属、有机溶剂的质量比为1：(0.5-5)：(1-3.5)。10 . The method according to claim 8 , wherein the mass ratio of the composite material, doped metal, and organic solvent in step (2) is 1:(0.5-5):(1-3.5). 11 .

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