A bamboo-like carbon nanotube with a heterogeneous structure, its preparation method, and its applications.

Abstract

This invention provides a bamboo-like carbon nanotube with a heterostructure, its preparation method, and its applications. The preparation method includes: dissolving cobalt nitrate and heteropolyacid in ethanol to obtain a first solution; dissolving dicyandiamide in a mixed solution of ethanol and water to obtain a second solution; mixing phytic acid with the second solution uniformly and performing a polymerization reaction to obtain a third solution; adding the first solution to the third solution to perform a chemically induced self-assembly reaction, washing and drying to obtain a dicyandiamide-heteropolyacid-phytic acid-cobalt ion organic polymer; and calcining to obtain the bamboo-like carbon nanotube with a heterostructure. This method is simple and inexpensive; the Co2P and WN / MoN nanoparticles in the bamboo-like carbon nanotube are uniformly distributed in the carbon matrix, improving the electrochemical performance of the material; the introduction of dicyandiamide and phytic acid enables nitrogen and phosphorus doping of the carbon framework, improving the conductivity of the carbon support; and the resulting product exhibits high capacity and excellent cycle stability as a cathode material for metal-air batteries.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochemical energy storage materials, in particular to a bamboo joint-like carbon nanotube with a heterostructure and a preparation method and application thereof. BACKGROUND

[0002] The development of sustainable energy conversion technology and system is one of the most promising alternatives to fossil energy, which is of great significance to alleviate the increasingly serious environmental pollution and energy crisis. In particular, rechargeable Zn-air batteries (ZABs) are considered as a possible energy storage solution due to their low cost, environmental friendliness and high safety.

[0003] However, the construction of high-activity oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) bifunctional air electrodes is largely hindered by their slow kinetics, resulting in a large electrochemical overpotential and a relatively low voltage output. So far, noble metal-based materials are considered to be the most effective ORR and OER electrocatalysts. However, noble metal-based electrocatalysts such as Pt / Pd (ORR catalyst) and IrO2 / RuO2(OER catalyst) exhibit limited bifunctional activity, which is less effective for the reverse reaction. At the same time, the scarcity, high price and poor durability of noble metal-based electrocatalysts seriously hinder their further large-scale application. Therefore, it is necessary to design a cost-effective and durable non-noble metal catalyst for long-lasting bifunctional oxygen catalysis in ZABs.

[0004] Based on the above background, the present application provides a low-cost and simple process in-situ nitridation and phosphorization method for preparing a Co2P-WN heterojunction composite material with a bamboo joint-like carbon nanotube structure uniformly loaded with Co2P and WN. SUMMARY

[0005] Based on the above description, the present application provides a bamboo joint-like carbon nanotube with a heterostructure and a preparation method and application thereof, to provide a low-cost and simple process in-situ nitridation and phosphorization method for preparing a composite material with Co2P and WN uniformly distributed in the bamboo joint-like carbon nanotube, to replace the noble metal-based electrocatalyst in the prior art.

[0006] The technical solution of the present application to solve the above technical problems is as follows:

[0007] In a first aspect, the present application provides a preparation method of a bamboo joint-like carbon nanotube with a heterostructure, comprising:

[0008] Step 1, dissolving cobalt nitrate and heteropoly acid in ethanol to obtain a first solution;

[0009] Step 2, dissolving dicyandiamide in a mixed solution of ethanol and water to obtain a second solution;

[0010] Step 3, uniformly mixing phytic acid with the second solution to obtain a third solution;

[0011] Step 4, adding the first solution into the third solution to perform a polymerization reaction, washing and drying to obtain a dicyanide-heteropoly acid-phytic acid-cobalt ion organic polymer;

[0012] Step 5, baking the dicyanide-heteropoly acid-phytic acid-cobalt ion organic polymer to obtain the bamboo-shaped carbon nanotube with a heterogeneous structure.

[0013] On the basis of the above technical solution, the application can be further improved as follows.

[0014] Further, the heteropoly acid in step 1 is phosphotungstic acid, phosphomolybdic acid or silicotungstic acid.

[0015] The mass ratio of the cobalt nitrate and the heteropoly acid is 1-2:0.1-1.

[0016] Further, the mass ratio of the dicyanide, the ethanol and the water in step 2 is 1-5:20-40:20-30.

[0017] Further, the mass ratio of the phytic acid and the second solution in step 3 is 0.1-1:50-60.

[0018] Further, the mixing temperature in step 3 is 20-100℃, and the reaction time is 1-5h.

[0019] Further, the baking temperature in step 4 is 600-1000℃, and the baking time is 3-10h.

[0020] In a second aspect, the application further provides the bamboo-shaped carbon nanotube with a heterogeneous structure prepared by the preparation method according to the first aspect.

[0021] On the basis of the above technical solution, the application can be further improved as follows.

[0022] Further, the cobalt phosphide and tungsten nitride nanoparticles are uniformly embedded in the structure carbon of the bamboo-shaped carbon nanotube.

[0023] In a third aspect, the application further provides the application of the bamboo-shaped carbon nanotube with a heterogeneous structure according to the second aspect as a redox electrocatalyst.

[0024] In a fourth aspect, the application further provides the application of the bamboo-shaped carbon nanotube with a heterogeneous structure according to the second aspect as an air cathode material of a rechargeable metal-air battery.

[0025] Compared with the prior art, the technical solution of the application has the following beneficial technical effects:

[0026] The application provides a preparation method of bamboo-shaped carbon nanotubes with a heterogeneous structure.

[0027] The bamboo-shaped carbon nanotubes with a heterogeneous structure can be applied to ORR / OER electrocatalytic reactions and metal-air battery cathode materials and can exhibit excellent electrochemical performance.

[0028] Compared with the prior art, the bamboo-shaped carbon nanotubes with a heterogeneous structure and the preparation method and application thereof have the following advantages:

[0029] 1. The synthesis method is simple and low in cost.

[0030] 2. The Co2P and WN / MoN nanoparticles in the bamboo-shaped carbon nanotubes with a heterogeneous structure are uniformly distributed in the carbon matrix, and the electrochemical performance of the material is effectively improved.

[0031] 3. The introduction of dicyandiamide and phytic acid can realize nitrogen and phosphorus doping of the carbon skeleton, improve the conductivity of the carbon carrier, adjust the electrochemical performance of the material, and make the product, i.e., the bamboo-shaped carbon nanotubes with a heterogeneous structure, exhibit high capacity and excellent cycle stability as a metal-air battery cathode material. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 FIG. 1 is a synthesis flowchart of the bamboo-shaped carbon nanotubes with a heterogeneous structure prepared in Example 1 of the application.

[0033] Figure 2 FIG. 2 is an XRD spectrum of the bamboo-shaped carbon nanotubes with a heterogeneous structure prepared in Example 1 of the application.

[0034] Figure 3 FIG. 3 is an XRD spectrum of the bamboo-shaped carbon nanotubes with a heterogeneous structure prepared in Example 2 and Example 3 of the application.

[0035] Figure 4 SEM images of the bamboo-shaped carbon nanotubes with heterogeneous structure prepared in Example 1 to Example 3 of the present application;

[0036] Figure 5 TEM, HRTEM, HADDF-STEM and EDSmapping images of each element of the bamboo-shaped carbon nanotubes with heterogeneous structure prepared in Example 1 of the present application;

[0037] Figure 6 Oxygen reduction performance curve of the bamboo-shaped carbon nanotubes with heterogeneous structure prepared in Example 1 to Example 3 of the present application;

[0038] Figure 7 Oxygen evolution performance curve of the bamboo-shaped carbon nanotubes with heterogeneous structure prepared in Example 1 to Example 3 of the present application and the comparative example;

[0039] Figure 8 Actual picture and open circuit voltage of the rechargeable zinc-air battery assembled by the bamboo-shaped carbon nanotubes with heterogeneous structure prepared in Example 1 of the present application;

[0040] Figure 9 Discharge curve of the rechargeable zinc-air battery assembled by the bamboo-shaped carbon nanotubes with heterogeneous structure prepared in Example 1 of the present application;

[0041] Figure 10 Cycling performance of the rechargeable zinc-air battery assembled by the bamboo-shaped carbon nanotubes with heterogeneous structure prepared in Example 1 of the present application and the comparative example. DETAILED DESCRIPTION

[0042] The present application will be further described in detail by specific examples, so that those skilled in the art can more clearly understand the present application.

[0043] The following examples are used to illustrate the present application, but not to limit the scope of the present application. Based on the specific examples in the present application, all other examples obtained by those skilled in the art without creative efforts are within the scope of the present application.

[0044] Constructing suitable catalytically active interfaces through interface engineering is an effective means of building bifunctional ORR / OER electrocatalysts. These interfaces can capture and activate protons to accelerate ORR kinetics and provide accessible sites to promote H-OH cleavage in the OER process. Transition metal nitrides (TMNs), as a class of Pt catalysts, exhibit moderate affinity for water molecules, protons, and atomic hydrogen, and have been extensively studied in the field of oxygen reduction. Transition metal phosphides (TMPs) are inexpensive and possess good conductivity, stability, rapid charge transfer, and improved reaction kinetics, attracting widespread attention in the field of water electrolysis. The rational design of interfacial synergistic heterostructures composed of TMNs and TMPs can be an effective approach to constructing bifunctional ORR / OER electrocatalysts for rechargeable metal-air batteries. These interfaces can capture and activate protons to accelerate ORR kinetics and provide accessible sites to promote H-OH cleavage in the OER process, thus enabling the construction of bifunctional ORR / OER electrocatalysts. However, no such materials have been reported to date.

[0045] To address the aforementioned issues, this invention provides a bamboo-like carbon nanotube with a heterogeneous structure, its preparation method, and its applications.

[0046] All raw materials used in the embodiments of this invention are commercially available analytical grade products, wherein the phytic acid mass percentage concentration is 70% and the density is 1.282 g / cm³. 3 .

[0047] In the examples, X-ray diffraction (XRD) characterization was performed using an XRD-6000 instrument manufactured by Shimadzu Corporation of Japan under CuKα, 40kV, and 30mA conditions.

[0048] The transmission electron microscope (TEM) results were obtained using a JEM-2100F transmission electron microscope (JEOL).

[0049] EDSmapping was performed using a FEITalos F200X equipped with a super-EDX and an energy filter (GatanGIFQuantumER965) in 200kV and STEM modes.

[0050] The preparation methods for bamboo-like carbon nanotubes with heterostructures include:

[0051] Step S1: Dissolve cobalt nitrate and heteropoly acid in ethanol to obtain the first solution.

[0052] The aforementioned heteropolyacids are phosphotungstic acid, phosphotomolybdic acid, or silicotungstic acid.

[0053] Correspondingly, when the heteropolyacid is phosphotungstic acid, the bamboo-like carbon nanotubes with heterostructure generated below are bamboo-like carbon nanotubes with cobalt phosphide-tungsten nitride heterostructure.

[0054] When the heteropoly acid is phosphomolybdic acid, the bamboo-like carbon nanotubes with heterostructure generated below are bamboo-like carbon nanotubes with cobalt phosphide-molybdenum nitride heterostructure.

[0055] When the heteropolyacid is silicotungstic acid, the bamboo-like carbon nanotubes with heterostructure generated below are bamboo-like carbon nanotubes with cobalt phosphide-tungsten nitride heterostructure.

[0056] The mass ratio of cobalt nitrate to heteropoly acid is 1-2:0.1-1, and the specific dosage can be set according to the actual situation.

[0057] Step S2: Dissolve dicyandiamide in a mixed solution of ethanol and water to obtain a second solution.

[0058] The mass ratio of dicyandiamide, ethanol and water is 1-5:20-40:20-30, and the specific dosage can be set according to the actual situation.

[0059] Step S3: Mix phytic acid with the second solution until homogeneous, and then polymerize to obtain the third solution.

[0060] The polymerization reaction temperature is 20–100℃, and the reaction time is 1–5 h.

[0061] The mass ratio of phytic acid to the second solution is 0.1–1:50–60. The specific dosage can be set according to the actual situation.

[0062] Step S4: Add the first solution to the third solution to carry out a chemically induced self-assembly reaction, wash and dry to obtain a dicyandiamide-heteropolyacid-phytic acid-cobalt ion organic polymer.

[0063] The roasting temperature is 600–1000℃, and the roasting time is 3–10 hours.

[0064] Step S5: Calcining the dicyandiamide-heteropolyacid-phytic acid-cobalt ion organic polymer yields bamboo-like carbon nanotubes with a heterostructure.

[0065] Combined with appendix Figure 1 As shown, the synthesis process and corresponding synthesis mechanism of the above preparation method are as follows:

[0066] First, cobalt nitrate and heteropolyacid are dispersed in an ethanol solution, and dicyandiamide is dissolved in a mixed solution of ethanol and deionized water. Then, phytic acid solution is added to the dicyandiamide solution. Finally, the ethanol solution of cobalt nitrate and heteropolyacid is slowly added dropwise to the mixed solution of dicyandiamide and phytic acid. Phytic acid molecules and cobalt ions are confined and fixed through coordination bonds and electrostatic interactions, thus forming a dicyandiamide-heteropolyacid-phytic acid-Co ion organic polymer. After high-temperature carbonization, a bamboo-like carbon nanotube structure carbon-supported Co2P-WN composite material is obtained.

[0067] In the prepared bamboo-shaped carbon nanotube structure carbon-supported Co2P-WN composite material, cobalt phosphide and tungsten nitride nanoparticles are uniformly embedded on the bamboo-shaped carbon nanotube structure carbon. Due to the uniform distribution of Co2P and WN, there are more defects and abundant catalytic active sites are exposed. Through the synergistic effect between Co2P and WN, the electrocatalytic redox performance of the material can be improved.

[0068] The prepared composite material exhibits excellent electrochemical performance as a redox electrocatalyst and an air cathode material for rechargeable metal-air batteries.

[0069] The following examples will further illustrate this point:

[0070] Example 1

[0071] This embodiment provides a method for preparing bamboo-like carbon nanotubes with a cobalt phosphide-tungsten nitride heterostructure, comprising the following steps:

[0072] In step S1, 5 mmol of cobalt nitrate and 0.3 g of phosphotungstic acid were dissolved in 20 mL of ethanol and ultrasonically dispersed to form a homogeneous first solution.

[0073] Step S2: After ultrasonic treatment, 50 mmol of dicyandiamide is dissolved in a mixed solution of 30 mL of ethanol and 25 mL of deionized water to form a second solution.

[0074] Step S3: Mix 0.3g of phytic acid thoroughly with the second solution and stir for 10 minutes to form the third solution.

[0075] Step S4: After slowly adding the first solution to the third solution, the mixture is rapidly stirred at room temperature for 1 hour and then dried in an 80°C water bath to obtain a dicyandiamide-phosphotungstic acid-phytic acid-Co ion organic polymer.

[0076] Step S5: The dried dicyandiamide-phosphotungstic acid-phytic acid-Co organic polymer is carbonized in a tube furnace at 800°C for 2 hours under N2 atmosphere to obtain a bamboo-like carbon nanotube structure carbon-supported Co2P-WN composite material, i.e., bamboo-like carbon nanotubes with heterostructure.

[0077] The synthesis mechanism of bamboo-like carbon nanotubes with heterogeneous structures is shown in the attached figure. Figure 1 As shown. The principle is as follows: First, cobalt nitrate and heteropolyacid are dispersed in an ethanol solution, and dicyandiamide is dissolved in a mixed solution of ethanol and deionized water; then, phytic acid solution is added to the dicyandiamide solution; finally, the ethanol solution of cobalt nitrate and heteropolyacid is slowly added dropwise to the mixed solution of dicyandiamide and phytic acid. Phytic acid molecules and cobalt ions are confined and fixed through coordination bonds and electrostatic interactions, thus forming a dicyandiamide-heteropolyacid-phytic acid-Co ion organic polymer; after high-temperature carbonization, the above composite material is obtained.

[0078] Example 2

[0079] This embodiment provides a method for preparing bamboo-like carbon nanotubes with a cobalt phosphide-molybdenum nitride heterostructure, comprising the following steps:

[0080] In step S1, 5 mmol of cobalt nitrate and 0.3 g of phosphomolybdic acid were dissolved in 20 mL of ethanol and ultrasonically dispersed to form a homogeneous first solution.

[0081] Step S2: After ultrasonic treatment, 50 mmol of dicyandiamide is dissolved in a mixed solution of 30 mL of ethanol and 25 mL of deionized water to form a second solution.

[0082] Step S3: Mix 0.3g of phytic acid thoroughly with the second solution and stir for 10 minutes to form the third solution.

[0083] Step S4: After slowly adding the first solution to the third solution, the mixture is rapidly stirred at room temperature for 1 hour and then dried in an 80°C water bath to obtain a dicyandiamide-phosphomolybdic acid-phytic acid-Co ion organic polymer.

[0084] Step S5: The dried dicyandiamide-phosphomolybdic acid-phytic acid-Co organic polymer is carbonized in a tube furnace at 800°C for 2 hours under N2 atmosphere to obtain a bamboo-like carbon nanotube structure carbon-supported Co2P-MoN composite material, that is, a bamboo-like carbon nanotube with a cobalt phosphide-molybdenum nitride heterostructure.

[0085] Example 3

[0086] This embodiment provides a method for preparing bamboo-like carbon nanotubes with a cobalt phosphide-tungsten nitride heterostructure, comprising the following steps:

[0087] In step S1, 5 mmol of cobalt nitrate and 0.3 g of silicotungstic acid were dissolved in 20 mL of ethanol and ultrasonically dispersed to form a homogeneous first solution.

[0088] Step S2: After ultrasonic treatment, 50 mmol of dicyandiamide is dissolved in a mixed solution of 30 mL of ethanol and 25 mL of deionized water to form a second solution.

[0089] Step S3: Mix 0.3g of phytic acid thoroughly with the second solution and stir for 10 minutes to form the third solution.

[0090] Step S4: After slowly adding the first solution to the third solution, the mixture is rapidly stirred at room temperature for 1 hour and then dried in an 80°C water bath to obtain a dicyandiamide-silicotungstic acid-phytic acid-Co ion organic polymer.

[0091] Step S5: The dried dicyandiamide-silicotungstic acid-phytic acid-Co organic polymer is carbonized in a tube furnace at 800°C for 2 hours under N2 atmosphere to obtain a bamboo-like carbon nanotube structure carbon-supported Co2P-WN composite material, that is, a bamboo-like carbon nanotube with a cobalt phosphide-tungsten nitride heterostructure.

[0092] Example 4

[0093] To verify the structure of the bamboo-like carbon nanotubes with heterogeneous structures prepared in Examples 1 to 3, this example performs a series of verification and characterization tests on the composite materials obtained in Examples 1 to 3:

[0094] like Figure 2 and Figure 3 As shown in the XRD pattern, the main characteristic peaks in Examples 1 and 3 are consistent with the standard Co2P and WN phases, indicating that the Co2P and WN phases exist simultaneously. The main characteristic peaks in Example 2 are consistent with the standard Co2P and MoN phases, indicating that the Co2P and MoN phases exist simultaneously. In addition, the results show that elemental cobalt is also present. Therefore, the composite material obtained in Example 2 contains not only the Co2P and MoN phases, but also elemental cobalt.

[0095] Figure 4 The image shown is a SEM image of the composite material obtained in Example 1, which shows a large area of ​​bamboo-like carbon nanotube structure.

[0096] Figure 5 The image shown is a TEM image of the composite material obtained in Example 1, which further demonstrates that there are a large number of nanoparticles on the bamboo-like carbon nanotubes. Figure 5 (a)); Figure 5 (b) The HRTEM image reveals that the prepared composite material is a typical graphitized carbon nanotube; Figure 5 The corresponding lattice fringes in the HRTEM image in (c) further illustrate the tight interface between Co2P and WN. The HRTEM images show lattice spacings of d = 0.251 nm and 0.221 nm, corresponding to the (1 0 0) and (1 2 1) planes of cubic WN and orthorhombic Co2P, respectively. Furthermore, Figure 5(d) HAADF-TEM and elemental distribution show that the Co2P and WN frameworks are uniformly distributed on the carbon matrix.

[0097] Example 5

[0098] This embodiment provides the application of the bamboo-like carbon nanotubes with a cobalt phosphide-tungsten nitride heterostructure prepared in Example 1 as an oxygen reduction electrocatalyst.

[0099] Specifically, it can be used as an electrocatalyst for oxygen reduction and oxygen evolution, with the following application: "Ink" is prepared using a bamboo-like carbon nanotube structure supported on a Co2P-WN composite material as the active material, isopropanol as the dispersion solution, and Nafion (5 wt%) as the binder. The mass ratio of the active material, isopropanol, and Nafion is determined to be 4:15:435. After thorough mixing of all components, 10 μL of the "ink" is dropped onto the working electrode of a rotating disk for oxygen reduction electrocatalytic performance testing.

[0100] Figure 6 The graphs show the oxygen evolution performance of the composite materials prepared in Examples 1-3 and the commercial 20wt% Pt / C material. The linear potential scan (LSV) curves were measured in the voltage range of 0.2-1.0V. The composite material with cobalt phosphide-tungsten nitride heterostructure obtained in Example 1 has a higher half-wave potential (0.80V), the composite material with cobalt phosphide-molybdenum nitride heterostructure obtained in Example 2 has a higher half-wave potential (0.81V), and the composite material with cobalt phosphide-tungsten nitride heterostructure obtained in Example 3 has a higher half-wave potential (0.79V), all of which are better than the half-wave potential of the commercial 20wt% Pt / C material (0.78V).

[0101] Figure 7 The graphs show the oxygen reduction performance of the composite materials prepared in Examples 1-3 and commercial RuO2, with linear potential scans (LSV) measured in the 1.2-1.8V range. The composite material with the cobalt phosphide-tungsten nitride heterostructure obtained in Example 1 is shown at a current density of 10 mA cm⁻¹. -2 The overpotential was 1.71V, and the composite material obtained in Example 2 was at 10mA cm⁻¹. -2 The overpotential was 1.67V, and the composite material obtained in Example 3 had an overpotential of 10mA / cm. -2 The overpotential was 1.69V, which is close to that of the comparative commercial RuO2 (1.56V).

[0102] Therefore, it can be seen that the bamboo-like carbon nanotubes with heterogeneous structures prepared in Examples 1 to 3 all have good performance in the application of oxygen reduction and oxygen evolution electrocatalysts.

[0103] Example 6

[0104] This embodiment provides the application of the bamboo-like carbon nanotubes with a cobalt phosphide-tungsten nitride heterostructure prepared in Example 1 as a cathode material for a rechargeable flexible zinc-air battery.

[0105] Specifically, to prepare the quasi-solid-state gel electrolyte, 1 g of polyvinyl alcohol (PVA) powder (molecular weight 205000 g / mol) was dissolved in 2 mL of 9 M potassium hydroxide (KOH) solution, 2 mL of 0.2 M acetic acid solution, and 10 mL of deionized water. The mixture was then heated to 90 °C and stirred continuously for 2 hours. Afterward, the solution was placed in a petri dish and allowed to solidify naturally at ambient temperature to form a thin gel film. The air cathode was prepared as follows: 20 mg of bamboo-shaped carbon nanotube-supported Co2P-WN composite material was dissolved in 850 μL of isopropanol solution and sonicated for 1 h. Then, 50 μL of Nafiton was added, and the mixture was sonicated for 30 minutes to obtain a uniform suspension. This suspension was then evenly coated onto treated carbon cloth (3 cm × 3 cm) using a pipette, with a catalyst loading of 1.25 mg / cm². 2 After drying, the zinc-air battery was assembled. A polished zinc plate (99.99% purity, 3×3cm) was used as the anode, and carbon cloth loaded with catalyst was used as the air cathode. The prepared gel electrolyte served as the "sandwich". The battery's discharge and constant current charge-discharge cycle performance were tested using the LANDCT2001A battery testing system to evaluate its energy storage capacity.

[0106] To further illustrate the superior performance of the bamboo-like carbon nanotubes with cobalt phosphide-tungsten nitride heterostructure assembled into a metal-air battery, a reference zinc-air battery assembled with commercially available noble metals ruthenium oxide / platinum carbon was used as a comparison.

[0107] Figure 8 The image shown is a physical picture of a flexible zinc-air battery assembled from bamboo-shaped carbon nanotubes with a cobalt phosphide-tungsten nitride heterostructure, which can achieve an open-circuit voltage of 1.425V.

[0108] Figure 9 The figure shows the discharge curve of the assembled zinc-air battery. The results indicate that at 1 mA / cm², the discharge rate is within acceptable limits. 2 A battery assembled from bamboo-like carbon nanotubes with a cobalt phosphide-tungsten nitride heterostructure can stably discharge for 14 hours at a given current density; combined with Figure 10 As can be seen, it can be stably charged and discharged for 20 hours, and its performance is far superior to that of flexible zinc-air batteries assembled from precious metals such as ruthenium oxide / platinum carbon.

[0109] Therefore, the bamboo-like carbon nanotubes with cobalt phosphide-tungsten nitride heterostructure prepared in Example 1 have good performance in the application of rechargeable flexible zinc-air battery cathodes.

[0110] In summary, the bamboo-like carbon nanotubes with heterogeneous structures and their preparation method provided in the embodiments of the present invention exhibit excellent electrochemical performance as electrocatalysts for oxygen reduction and oxygen evolution, and as air cathode materials for rechargeable metal-air batteries.

[0111] Compared to existing technologies, it has the following advantages:

[0112] 1. The synthesis method is simple and inexpensive;

[0113] 2. In the obtained bamboo-like carbon nanotubes with heterogeneous structure, Co2P and WN / MoN nanoparticles are uniformly distributed in the carbon matrix, which effectively improves the electrochemical performance of the material.

[0114] 3. The introduction of dicyandiamide and phytic acid can achieve nitrogen and phosphorus doping of the carbon skeleton, improve the conductivity of the carbon support, and regulate the electrochemical performance of the material. As a result, the prepared product has a heterogeneous bamboo-like carbon nanotube, which exhibits high capacity and excellent cycle stability as a cathode material for metal-air batteries.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing a bamboo-like carbon nanotube having a heterogeneous structure, characterized by, The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure.

2. The method of claim 1, wherein the bamboo-like carbon nanotube having a heterostructure is prepared by the steps of: (a) preparing a bamboo-like carbon nanotube; (b) coating the bamboo-like carbon nanotube with a metal; and (c) removing the metal from the bamboo-like carbon nanotube. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure.

3. The method for preparing bamboo-like carbon nanotubes with heterogeneous structures according to claim 1, characterized in that, The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure.

4. The method for preparing bamboo-like carbon nanotubes with heterogeneous structures according to claim 1, characterized in that, The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure.

5. The method of claim 1, wherein the bamboo-like carbon nanotube having a heterostructure is prepared by the steps of: (a) preparing a bamboo-like carbon nanotube; (b) coating the bamboo-like carbon nanotube with a metal; and (c) removing the metal from the bamboo-like carbon nanotube. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure.

6. The method for preparing bamboo-like carbon nanotubes with heterogeneous structures according to claim 1, characterized in that, The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure.

8. The heterostructured bamboo-like carbon nanotube according to claim 7, wherein The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application relates to a preparation method of a bamboo-shaped carbon nanotube with a heterogeneous structure. The application

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