CN115207378B - A kind of polypyrrole nanotube electrocatalyst and its preparation method and application - Google Patents

Abstract

The invention discloses a polypyrrole nanotube electrocatalyst and its preparation method and application. The preparation method comprises the following steps: dispersing transition metal oxides or transition metal soluble salts in water, stirring until completely dissolved, and obtaining a first solution Add methyl orange to the first solution, stir until completely dissolved, and add ferric chloride to obtain the second solution; add pyrrole monomer to the second solution, stir and polymerize, and obtain a transition metal oxide or transition Polypyrrole nanotubes of metal salts; the polypyrrole nanotubes wrapped with transition metal oxides or transition metal salts are calcined under reducing atmosphere to obtain polypyrrole nanotube electrocatalysts wrapped with transition metal simple substances. The method is reasonable in design and convenient in operation, and an electrocatalyst with good catalytic performance, high specific surface area and porosity, and gas channels with good electronic conductivity and mechanical strength is obtained.

Description

A kind of polypyrrole nanotube electrocatalyst and its preparation method and application

technical field

The invention belongs to the field of battery electrode materials, and relates to a polypyrrole nanotube electrocatalyst and a preparation method and application thereof.

Background technique

As a green and sustainable energy technology, batteries meet the needs of today's social development. Among them, metal-air batteries have attracted much attention because of their high theoretical energy density, good safety, low cost, and environmental protection. The selection of electrode materials for electrocatalysts in metal-air batteries is crucial to battery performance. The positive electrode electrocatalyst material for metal-air batteries needs to realize the dual functions of gas channel and catalyst support, and needs to have high electronic conductivity, high specific surface area and porosity, and high mechanical strength. Currently commonly used electrocatalysts are noble metal catalysts represented by Pt, Ir, etc., but noble metal resources are scarce and costly, making it difficult to apply them industrially. Transition metal compounds have the advantages of abundant reserves in the earth's crust, low price, strong alkali resistance, and strong oxidation resistance. As an efficient non-precious metal catalyst, they have become a research hotspot. However, such catalysts currently suffer from disadvantages such as poor electrical conductivity and low exposure of catalytic active sites, resulting in unsatisfactory catalytic performance.

Contents of the invention

Aiming at the problems existing in the prior art, the present invention provides a polypyrrole nanotube electrocatalyst and its preparation method and application. As a conductive polymer, polypyrrole has good electrical conductivity which is beneficial to electron transport, and the tubular structure provides high The specific surface area increases the catalytically active sites. Therefore, an electrocatalyst with good catalytic performance, high specific surface area and porosity, and good electronic conductivity and mechanical strength in gas channels is obtained.

The present invention is achieved through the following technical solutions:

A preparation method of polypyrrole nanotube electrocatalyst, comprising the following steps:

S1: Dispersing transition metal oxides or transition metal soluble salts in water, stirring until completely dissolved, to obtain a first solution;

S2: Add methyl orange to the first solution, stir until completely dissolved, and add ferric chloride to obtain the second solution;

S3: adding pyrrole monomers to the second solution, stirring and polymerizing, obtaining polypyrrole nanotubes wrapped with transition metal oxides or transition metal salts;

S4: Calcining the polypyrrole nanotubes wrapped with a transition metal oxide or transition metal salt in a reducing atmosphere to obtain a polypyrrole nanotube electrocatalyst wrapped with a transition metal simple substance.

Preferably, the transition metal oxide is any one of CoO, CuO, Fe ₂ O ₃ and NiO.

Preferably, the soluble salt of transition metal is any one of CoCl ₂ , CuCl ₂ , FeCl ₃ and NiCl ₂ .

Preferably, the pyrrole monomer is purified by vacuum distillation before being added to the reaction system; the temperature of the vacuum distillation is 80° C. to 100° C., and the pressure is 0.08 MPa.

Preferably, the reducing atmosphere includes a hydrogen atmosphere or a carbon monoxide atmosphere.

Preferably, the calcination temperature is 400-600°C.

Preferably, the molar ratio of the pyrrole monomer to the transition metal in the transition metal oxide or soluble salt is 1:(0.5-2.5).

Preferably, the concentration range of the methyl orange is 3mmol/L-5mmol/L, and the ratio of the amount of the pyrrole monomer to the ferric chloride is 1:(0.5-2.5).

A polypyrrole nanotube electrocatalyst prepared by the above method, the specific surface area of the polypyrrole nanotube electrocatalyst is ^600-820m2 /g; the power density of the polypyrrole nanotube electrocatalyst is 70-154mW·cm ^-2 .

Application of the polypyrrole nanotube electrocatalyst prepared by the above preparation method in a metal-air battery.

Compared with the prior art, the present invention has the following beneficial technical effects:

A method for preparing polypyrrole nanotube electrocatalysts, using methyl orange as a soft template, ferric chloride as an oxidant, and polymerizing pyrrole monomers to prepare polypyrrole nanotubes. The tubular structure can be used as a gas channel to increase metal - Catalytic efficiency of air battery electrocatalysts, while adding transition metal oxides or transition metal soluble salts in the reaction system, in the synthesis process of polypyrrole nanotubes, transition metal oxides or transition metal soluble salts The polypyrrole nanotubes are wrapped in the inside of the polypyrrole nanotubes, and at the same time, they are calcined in a reducing atmosphere to obtain polypyrrole nanotubes wrapped with a transition metal element. During the calcination process, the polypyrrole nanotubes form a more stable nitrogen-carbon (N-C) structure. , forming a (metal-nitrogen-carbon) M-N-C type polypyrrole nanotube electrocatalyst with good performance. The method is reasonable in design and convenient in operation, and an electrocatalyst with good catalytic performance, high specific surface area and porosity, and gas channels with good electronic conductivity and mechanical strength is obtained.

Further, the pyrrole monomer is purified by vacuum distillation before the polymerization reaction, which can effectively reduce the purity of the synthesized polypyrrole nanotubes.

Further, the calcination temperature is 400-600°C. On the one hand, it ensures the structural stability of polypyrrole nanotubes, and on the other hand, it can effectively reduce the transition metal oxide or transition metal solubility to transition Elemental metal.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus It should be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings based on these drawings without creative work.

Fig. 1 is the schematic flow sheet of a kind of polypyrrole nanotube electrocatalyst preparation method among the present invention;

Fig. 2 is the SEM image of the polypyrrole nanotube electrocatalyst prepared in Example 3 of the present invention under different magnifications.

3 is a TEM image of the polypyrrole nanotube electrocatalyst prepared in Example 3 of the present invention.

Detailed ways

In order to enable those skilled in the art to understand the features and effects of the present invention, the terms and terms mentioned in the specification and claims are generally described and defined below. Unless otherwise specified, all technical and scientific terms used herein have the usual meanings understood by those skilled in the art for the present invention. In case of conflict, the definitions in this specification shall prevail.

The theories or mechanisms described and disclosed herein, whether true or false, should not limit the scope of the present invention in any way, ie, the present invention can be practiced without being limited by any particular theory or mechanism.

Herein, all the features defined in the form of numerical range or percentage range, such as numerical value, quantity, content and concentration, are only for the sake of brevity and convenience. Accordingly, the recitation of a numerical range or a percentage range should be deemed to encompass and specifically disclose all possible subranges and individual values (including integers and fractions) within those ranges.

In this article, unless otherwise specified, "comprising", "comprising", "comprising", "having" or similar expressions cover the meanings of "consisting of" and "consisting mainly of", for example, "A contains a " covers the meanings of "A contains a and others" and "A contains only a".

Herein, for the sake of concise description, all possible combinations of the technical features in each embodiment or embodiment are not described. Therefore, as long as there is no contradiction in the combination of these technical features, each technical feature in each embodiment or example can be combined arbitrarily, and all possible combinations should be regarded as within the scope of this specification.

Studies have shown that the direct use of non-noble metals as electrocatalysts has low catalytic efficiency. At present, the catalytic efficiency is mainly improved by doping, which mainly includes co-doped carbon with transition metal heteroatoms, and heteroatom doped with N, B, S, O, P, etc. miscellaneous. At present, in non-metal doping modification, nitrogen atoms can be doped to the edge or inside of the carbon structure to generate corresponding active sites due to the similar size of nitrogen and carbon atoms. Because nitrogen doping is easier to achieve than other heteroatom doping, and can produce many corresponding active sites, transition metal and nitrogen-doped carbon catalysts have become more practical and promising catalysts to replace noble metals, called It is a transition metal and nitrogen modified carbon catalyst, referred to as M-N-C catalyst. This heteroatom-modified carbon catalytic material is considered as a potential substitute for noble metal catalysts due to its cheapness, stability, and good electrical conductivity. However, the M-N-C catalysts reported in the current study have the disadvantages of complex synthetic pathways and unsatisfactory catalytic efficiency.

The invention selects polypyrrole as the basic material, and the polypyrrole has an N-C structure molecular basis, which can effectively improve the electronic conductivity of the catalyst to achieve high catalytic efficiency. At the same time, through the induction of the template agent in the polymerization process of polypyrrole, various shapes such as circular tubes and square tubes can be realized. These natural pore structures can be used as gas channels to improve the catalytic efficiency of metal-air battery electrocatalysts. And, by controlling the reaction conditions, the pore size of the polypyrrole tube can be adjusted. Therefore, the present invention can regulate the morphology and diameter of the polypyrrole nanotube according to the actual application conditions by using the polypyrrole nanotube as a loading agent for the transition metal, thereby Regulate the loading capacity and gas flux of the catalyst. As a conductive polymer, polypyrrole itself has the advantages of high electronic conductivity and high mechanical strength. By controlling the reaction conditions, polypyrrole nanotubes with a hollow structure can be prepared to achieve a high specific surface area. At the same time, polypyrrole itself has antiseptic properties. It can be seen that polypyrrole nanotubes are an electrode electrocatalyst material with various excellent properties, and also have good anti-corrosion properties.

In order to construct the above-mentioned polypyrrole nanotube electrocatalyst with excellent performance, its preparation method is shown in Figure 1, specifically:

S1: Dispersing transition metal oxides or transition metal soluble salts in water, stirring until completely dissolved, to obtain a first solution;

Wherein, the transition metal oxide includes any one of CoO, CuO, Fe ₂ O ₃ and NiO. Soluble salts of transition metals include any one of CoCl ₂ , CuCl ₂ , FeCl ₃ and NiCl ₂ . The molar ratio of the pyrrole monomer to the transition metal in the transition metal oxide or soluble salt is 1:(0.5-2.5).

S2: Add methyl orange to the first solution, stir until completely dissolved, and add ferric chloride to obtain a second solution; wherein the concentration of methyl orange is in the range of 3mmol/L-5mmol/L.

S3: Add pyrrole monomer to the second solution, stir and polymerize, and obtain polypyrrole nanotubes wrapped with transition metal oxide or transition metal salt; wherein, the ratio of the amount of pyrrole monomer to ferric chloride is 1 : (0.5～2.5), and the pyrrole monomer is purified by vacuum distillation before the polymerization reaction; the temperature of vacuum distillation is 80°C-100°C, and the pressure is 0.08MPa.

S4: Calcining the polypyrrole nanotubes wrapped with a transition metal oxide or transition metal salt in a reducing atmosphere to obtain a polypyrrole nanotube electrocatalyst wrapped with a transition metal simple substance.

Wherein, the reducing atmosphere includes a hydrogen atmosphere or a carbon monoxide atmosphere; the calcining temperature is 400-600°C.

The diameter of the polypyrrole nanotube electrocatalyst prepared by the above method is 80-200nm, the specific surface area is 600-820m ² /g, and the power density is 70-154mW·cm ^-2 .

Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Conventional instruments and equipment in the art are used in the following examples. For the experimental methods without specific conditions indicated in the following examples, the conventional conditions or the conditions suggested by the manufacturer are usually followed. Various raw materials are used in the following examples. Unless otherwise specified, conventional commercially available products are used, and their specifications are conventional specifications in the art. In the description of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

Example 1

The pyrrole monomer was purified by vacuum distillation, the temperature of the vacuum distillation was 80° C., and the pressure was 0.08 MPa. Take 0.55g CuCl ₂ and disperse it in 300mL deionized water, stir at room temperature for 30min to make it completely dissolve. Dissolve 300mg of methyl orange in 300mL of the above solution, stir at room temperature for 5 hours until the solution turns clear pink, then slowly add 2.22g of ferric chloride hexahydrate, and the solution immediately appears dark red flocculent precipitate. Continue to stir rapidly for 50 min, then add 1.1 g of pyrrole monomer, observe that the solution turns black and green, and polymerize at room temperature (25 ° C) for 24 h by in situ polymerization, and obtain polypyrrole nanotubes wrapped with CuCl ₂ . After suction filtration, the product was repeatedly washed with deionized water and absolute ethanol to remove the template, unreacted pyrrole monomer and FeCl ₃ ·6H ₂ O until the pH value was neutral, and dried. The polypyrrole nanotubes coated with CuCl ₂ obtained after drying were placed in a hydrogen atmosphere, and calcined at 400° C. to obtain a polypyrrole nanotube electrocatalyst coated with Cu simple substance.

The Cu-wrapped polypyrrole nanotube electrocatalyst prepared in this example has a tube diameter of 80 nm, a specific surface area of 600 m ² /g, and a power density of 70 mW·cm ^-2 .

Example 2

The pyrrole monomer was purified by vacuum distillation, the temperature of vacuum distillation was 90° C., and the pressure was 0.08 MPa. Take 0.55g CuCl ₂ and disperse it in 490mL deionized water, stir at room temperature for 30min to make it completely dissolve. Dissolve 300mg of methyl orange in 300mL of the above solution, stir at room temperature for 5 hours until the solution turns clear pink, then slowly add 2.22g of ferric chloride hexahydrate, and the solution immediately appears dark red flocculent precipitate. Continue to stir rapidly for 50 min, then add 1.1 g of pyrrole monomer, observe that the solution turns black and green, and polymerize at room temperature (25 ° C) for 24 h by in situ polymerization, and obtain polypyrrole nanotubes wrapped with CuCl ₂ . After suction filtration, the product was repeatedly washed with deionized water and absolute ethanol to remove the template, unreacted pyrrole monomer and FeCl ₃ ·6H ₂ O until the pH value was neutral, and dried. The polypyrrole nanotubes coated with CuCl ₂ obtained after drying were placed in a hydrogen atmosphere, and calcined at 440° C. to obtain a polypyrrole nanotube electrocatalyst coated with Cu simple substance.

The Cu-wrapped polypyrrole nanotube electrocatalyst prepared in this example has a tube diameter of 100 nm, a specific surface area of 700 m ² /g, and a power density of 78 mW·cm ^-2 .

Example 3

The pyrrole monomer was purified by vacuum distillation, the temperature of vacuum distillation was 100° C., and the pressure was 0.08 MPa. Take 0.55g CuCl ₂ and disperse it in 490mL deionized water, stir at room temperature for 30min to make it completely dissolve. Dissolve 300mg of methyl orange in 300mL of the above solution, stir at room temperature for 5 hours until the solution turns clear pink, then slowly add 6.65g of ferric chloride hexahydrate, and the solution immediately appears dark red flocculent precipitate. Continue to stir rapidly for 50 min, then add 1.1 g of pyrrole monomer, observe that the solution turns black and green, and polymerize at room temperature (25 ° C) for 24 h by in situ polymerization, and obtain polypyrrole nanotubes wrapped with CuCl ₂ . After suction filtration, the product was repeatedly washed with deionized water and absolute ethanol to remove the template, unreacted pyrrole monomer and FeCl ₃ ·6H ₂ O until the pH value was neutral, and dried. The polypyrrole nanotubes coated with CuCl ₂ obtained after drying were placed in a hydrogen atmosphere, and calcined at 550° C. to obtain a polypyrrole nanotube electrocatalyst coated with Cu simple substance.

The Cu-wrapped polypyrrole nanotube electrocatalyst prepared in this example has a tube diameter of 120 nm, a specific surface area of 720 m ² /g, and a power density of 80 mW·cm ^-2 .

The SEM picture of the polypyrrole nanotube wrapped with Cu simple substance prepared by the present invention is shown in Figure 2, and the TEM picture is shown in Figure 3. It can be seen from the figure that the pyrrole nanotube is about 80-200nm and presents a hollow tubular structure. And the interior is wrapped with a transition metal element.

Example 4

The pyrrole monomer was purified by vacuum distillation, the temperature of the vacuum distillation was 95° C., and the pressure was 0.08 MPa. Take 1.65g CoCl ₂ and disperse it in 490mL deionized water, stir at room temperature for 30min to make it completely dissolve. Dissolve 300mg of methyl orange in 300mL of the above solution, stir at room temperature for 5 hours until the solution turns clear pink, then slowly add 6.65g of ferric chloride hexahydrate, and the solution immediately appears dark red flocculent precipitate. Continue to stir rapidly for 50 minutes, then add 1.1 g of pyrrole monomer, observe that the solution turns black and green, and polymerize at room temperature (25° C.) for 24 hours by in-situ polymerization, and obtain polypyrrole nanotubes wrapped with CoCl ₂ . After suction filtration, the product was repeatedly washed with deionized water and absolute ethanol to remove the template, unreacted pyrrole monomer and FeCl ₃ ·6H ₂ O until the pH value was neutral, and dried. The polypyrrole nanotubes coated with CoCl ₂ obtained after drying were placed in a hydrogen atmosphere, and calcined at 450 ° C to obtain a polypyrrole nanotube electrocatalyst coated with a Co metal element.

The polypyrrole nanotube electrocatalyst coated with Co simple substance prepared in this example has a tube diameter of 140 nm, a specific surface area of 750 m ² /g, and a power density of 90 mW·cm ^-2 .

Example 5

The pyrrole monomer was purified by vacuum distillation, the temperature of vacuum distillation was 85° C., and the pressure was 0.08 MPa. Take 1.65g CoO and disperse it in 490mL deionized water, stir at room temperature for 30min to make it completely dissolved. Dissolve 300mg of methyl orange in 300mL of the above solution, stir at room temperature for 5 hours until the solution turns clear pink, then slowly add 6.65g of ferric chloride hexahydrate, and the solution immediately appears dark red flocculent precipitate. Continue to stir rapidly for 50 minutes, then add 1.1 g of pyrrole monomer, observe that the solution turns black and green, and polymerize at room temperature (25° C.) for 24 hours by in-situ polymerization, and obtain polypyrrole nanotubes coated with CoO. After suction filtration, the product was repeatedly washed with deionized water and absolute ethanol to remove the template, unreacted pyrrole monomer and FeCl ₃ ·6H ₂ O until the pH value was neutral, and dried. The polypyrrole nanotubes coated with CoO obtained after drying were placed in a hydrogen atmosphere, and calcined at 470° C. to obtain a polypyrrole nanotube electrocatalyst coated with Co simple substance.

The polypyrrole nanotube electrocatalyst coated with Co simple substance prepared in this example has a tube diameter of 160 nm, a specific surface area of 780 m ² /g, and a power density of 110 mW·cm ^-2 .

Example 6

A preparation method of polypyrrole nanotube electrocatalyst, is characterized in that, comprises the following steps:

S1: Disperse CoO in water and stir until completely dissolved to obtain the first solution;

S2: Add 3mmol/L methyl orange to the first solution, stir until completely dissolved, and add ferric chloride to obtain the second solution;

S3: Add pyrrole monomer to the second solution, the ratio of the amount of pyrrole monomer to ferric chloride is 1:0.5, and the molar ratio of pyrrole monomer to Co is 1:0.5; after in-situ polymerization occurs after stirring , to obtain polypyrrole nanotubes wrapped with CoO;

S4: placing the CoO-wrapped polypyrrole nanotubes in a carbon monoxide atmosphere and calcining at 400° C. to obtain a Co-wrapped polypyrrole nanotube electrocatalyst.

The polypyrrole nanotube electrocatalyst coated with Co simple substance prepared in this example has a tube diameter of 180 nm, a specific surface area of 800 m ² /g, and a power density of 115 mW·cm ^-2 .

Example 7

A preparation method of polypyrrole nanotube electrocatalyst, is characterized in that, comprises the following steps:

S1: Disperse CuO in water and stir until completely dissolved to obtain the first solution;

S2: Add 4mmol/L methyl orange to the first solution, stir until completely dissolved, and add ferric chloride to obtain the second solution;

S3: Add pyrrole monomer to the second solution, the ratio of the amount of pyrrole monomer to ferric chloride is 1:1.5, and the molar ratio of pyrrole monomer to Cu is 1:1; after in-situ polymerization occurs after stirring , to obtain polypyrrole nanotubes wrapped with CuO;

S4: placing the CuO-wrapped polypyrrole nanotubes in a carbon monoxide atmosphere, and calcining them at 500° C. to obtain a Cu-wrapped polypyrrole nanotube electrocatalyst.

The Cu-wrapped polypyrrole nanotube electrocatalyst prepared in this example has a tube diameter of 190 nm, a specific surface area of 820 m ² /g, and a power density of 125 mW·cm ^-2 .

Example 8

A preparation method of polypyrrole nanotube electrocatalyst, is characterized in that, comprises the following steps:

S1: Disperse NiO in water and stir until it is completely dissolved to obtain the first solution;

S2: Add 5 mmol/L methyl orange to the first solution, stir until completely dissolved, and add ferric chloride to obtain the second solution;

S3: Add pyrrole monomer to the second solution, the ratio of the amount of pyrrole monomer to ferric chloride is 1:2, and the molar ratio of pyrrole monomer to Ni is 1:1.5; after in-situ polymerization occurs after stirring , to obtain polypyrrole nanotubes wrapped with NiO;

S4: placing the NiO-wrapped polypyrrole nanotubes in a hydrogen atmosphere, and calcining them at 600° C. to obtain a Ni simple substance-wrapped polypyrrole nanotube electrocatalyst.

The polypyrrole nanotube electrocatalyst coated with simple substance Ni obtained in this example has a diameter of 200 nm, a specific surface area of 820 m ² /g, and a power density of 135 mW·cm ^-2 .

Example 9

A preparation method of polypyrrole nanotube electrocatalyst, is characterized in that, comprises the following steps:

S1: Disperse Fe ₂ O ₃ in water and stir until completely dissolved to obtain the first solution;

S2: Add 5 mmol/L methyl orange to the first solution, stir until completely dissolved, and add ferric chloride to obtain the second solution;

S3: Add pyrrole monomer to _the second solution, the ratio of the amount of pyrrole monomer to ferric chloride is 1:2, and the molar ratio of pyrrole monomer to Fe in _Fe2O3 is 1:2.5; stirring occurs After the in-situ polymerization reaction, polypyrrole nanotubes wrapped with Fe ₂ O ₃ are obtained;

S4: placing the polypyrrole nanotubes wrapped with Fe ₂ O ₃ in a hydrogen atmosphere, and calcining at 600° C. to obtain a polypyrrole nanotube electrocatalyst wrapped with Fe simple substance.

The polypyrrole nanotube electrocatalyst coated with Fe simple substance prepared in this example has a tube diameter of 195 nm, a specific surface area of 800 m ² /g, and a power density of 150 mW·cm ^-2 .

Example 10

A preparation method of polypyrrole nanotube electrocatalyst, is characterized in that, comprises the following steps:

S1: Disperse NiO in water and stir until it is completely dissolved to obtain the first solution;

S2: Add 5 mmol/L methyl orange to the first solution, stir until completely dissolved, and add ferric chloride to obtain the second solution;

S3: Add pyrrole monomer to the second solution, the ratio of the amount of pyrrole monomer to ferric chloride is 1:2.5, and the molar ratio of pyrrole monomer to Ni in NiO is 1:2.5; stirring in situ polymerization After the reaction, polypyrrole nanotubes wrapped with NiO are obtained;

S4: placing the NiO-wrapped polypyrrole nanotubes in a hydrogen atmosphere, and calcining at 600° C. to obtain a Ni simple substance-wrapped polypyrrole nanotube electrocatalyst.

The polypyrrole nanotube electrocatalyst coated with Ni simple substance prepared in this example has a tube diameter of 201 nm, a specific surface area of 810 m ² /g, and a power density of 155 mW·cm ^-2 .

Example 11

The difference between this embodiment and embodiment 10 is that _NiCl was added for reaction.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications should also be It is regarded as the protection scope of the present invention.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that The technical solution of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solution of the present invention.

Claims (7)

1. The preparation method of the polypyrrole nanotube electrocatalyst coated with the transition metal simple substance is characterized by comprising the following steps of:

s1: dispersing an oxide of a transition metal in water, stirring to obtain a first dispersion liquid, or dispersing a soluble salt of the transition metal in water, and stirring until the soluble salt is completely dissolved to obtain a first solution;

s2: adding methyl orange into the first dispersion liquid or the first solution, stirring until the methyl orange is completely dissolved, and adding ferric chloride to obtain a second dispersion liquid or a second solution;

s3: adding pyrrole monomer into the second dispersion liquid or the second solution, stirring and polymerizing to obtain polypyrrole nanotube coated with transition metal oxide or transition metal salt;

s4: calcining the polypyrrole nanotube wrapped with the transition metal oxide or the transition metal salt in a reducing atmosphere to obtain a polypyrrole nanotube electrocatalyst wrapped with a transition metal simple substance;

the calcining temperature is 400-600 ℃;

the mole ratio of the pyrrole monomer to the transition metal in the oxide or soluble salt of the transition metal is 1 (0.5-2.5);

the concentration range of the methyl orange is 3 mmol/L-5 mmol/L, and the ratio of the pyrrole monomer to the ferric chloride substance is 1 (0.5-2.5);

the pipe diameter of the polypyrrole nanotube electrocatalyst is 80-200 nm;

the transition metal is Co, cu, fe or Ni.

2. Polypyrrole nanotube electrocatalyst coated with elemental transition metal according to claim 1Characterized in that the oxide of the transition metal is CoO, cuO, fe ₂ O ₃ And any one of NiO.

3. The method for preparing polypyrrole nanotube electrocatalyst coated with transition metal element according to claim 1, wherein the soluble salt of transition metal is CoCl ₂ 、CuCl ₂ 、FeCl ₃ And NiCl ₂ Any one of the following.

4. The method for preparing the polypyrrole nanotube electrocatalyst coated with the transition metal simple substance according to claim 1, wherein the pyrrole monomer is purified by vacuum distillation before being added into a reaction system; the temperature of reduced pressure distillation is 80-100 ℃ and the pressure is 0.08MPa.

5. The method for preparing the polypyrrole nanotube electrocatalyst coated with the transition metal element according to claim 1, wherein the reducing atmosphere comprises a hydrogen atmosphere or a carbon monoxide atmosphere.

6. The polypyrrole nanotube electrocatalyst coated with transition metal element prepared by the method of any one of claims 1 to 5, wherein the polypyrrole nanotube electrocatalyst has a specific surface area of 600 to 820 ² /g; the power density of the polypyrrole nanotube electrocatalyst is 70-154 mW.cm ^-2 。

7. The polypyrrole nanotube electrocatalyst coated with transition metal element prepared by the preparation method of any one of claims 1 to 5, and application thereof in metal-air batteries.