CN113697861A

CN113697861A - Composite material and preparation method and application thereof

Info

Publication number: CN113697861A
Application number: CN202110919291.4A
Authority: CN
Inventors: 赵斌元; 王礼建; 宁月生; 赖奕坚
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2021-08-11
Filing date: 2021-08-11
Publication date: 2021-11-26

Abstract

The invention relates to the field of nano material technology and energy science, in particular to a composite material and a preparation method and application thereof. A composite material comprises hollow carbon nanomaterial and Fe₃O₄The hollow carbon nano material is of a sunken bowl-shaped structure, and Fe is loaded on a sunken part in the bowl-shaped structure₃O₄A nanoparticle; the bowl wall of the bowl-shaped structure is of a hierarchical porous structure, the hierarchical porous structure comprises macropores, micropores and mesopores, the pore diameter of the macropores is larger than 50nm, the pore diameter of the micropores is smaller than 2nm, and the pore diameter of the mesopores is 2 nm-50 nm. The application relates to the preparation of Fe with a particle size of less than 50nm by incipient wetness impregnation₃O₄The nano particles are uniformly dispersed in the concave part of the bowl-shaped structure of the hollow carbon nano material, and by controlling the times of primary wet impregnation, Fe with different contents can be controllably synthesized in the concave part₃O₄And (3) nanoparticles.

Description

Composite material and preparation method and application thereof

Technical Field

The invention relates to the field of nano material technology and energy science, in particular to a composite material and a preparation method and application thereof.

Background

Super capacitors have received a great deal of attention from researchers as an environmentally friendly, efficient energy storage and conversion device. It is widely used in various fields such as digital communication equipment, backup power systems, hybrid vehicles and portable electronic products because of its outstanding characteristics of high power density, rapid charging/discharging capability, wide operating temperature range, little environmental pollution and long service life.

There are two different types of energy storage mechanisms in supercapacitor devices, Electric Double Layer Capacitance (EDLC) and faraday Pseudocapacitance (PC), respectively. EDLCs use the formation of opposite electron or ion alignments between the interface of a carbon electrode and an electrolyte to cause charges to accumulate on the accessible surface of the electrode/electrolyte. Carbon-based materials, such as porous carbon, carbon nanofibers, carbon nanotubes, and graphene, are widely used as EDLC electrode materials due to their high specific surface area, excellent pore size structure, good electrical conductivity, and low cost. However, the limited specific capacitance of EDLCs limits their use in practical energy storage applications. Faradaic pseudocapacitance is a capacitance produced by rapid and reversible redox reactions or by chemical adsorption/desorption reactions at and near the surface, and its capacitance value is much higher than that of EDLC. However, the electron and ion conductivities of pseudocapacitive electrode materials are poor, resulting in electrode materials with relatively poor rate performance and cycling stability. Therefore, in order to obtain better overall electrochemical performance, it is necessary to design a composite material combining these two charge storage mechanisms, to circumvent the disadvantages of electric double layer capacitors and pseudocapacitors, and to exhibit better energy density and recycling stability.

Among the various pseudocapacitive electrode materials, Fe₃O₄The material is economic, efficient and environment-friendly, and has high specific capacitance due to oxidation state components and high sensitivity of reversible redox Faraday reaction in aqueous solution. For example, Vijayamohanan et al studied Fe₃O₄The faraday reaction mechanism in aqueous solution is based roughly on the following equation: fe₃O₄ ⁺2e^-+4H₂O→3Fe(OH)₂+2OH^-. However, Fe is due to its lower specific surface area and less porosity₃O₄Nanoparticles tend to clump together and are poorly conductive and have slow ion diffusion rates during charge/discharge. Thus, Fe is caused₃O₄Nanoparticles exhibit poor specific capacitance, high interfacial resistance, low rate performance and short cycle life in aqueous electrolytes when used as electrode materials for supercapacitors. To address this limitation, one of the most effective methods is to complex Fe with a carbon material having a higher specific surface area and better electrical conductivity₃O₄And (3) nanoparticles. In particular, hollow carbon nanomaterials as novel nanostructuresThe material has wide application prospect in the field of electrochemical energy storage due to high specific surface area, low density, larger cavity volume, thinner carbon shell thickness and high conductivity. The hollow porous structure is favorable for electrolyte diffusion and ion transmission, and the hollow structure of the hollow carbon nanomaterial can be used for loading active oxide nanoparticles, so that structural variation and performance attenuation of the hollow carbon nanomaterial in an electrochemical process are greatly inhibited. However, in most of the studies at present, Fe, which is inferior in conductivity₃O₄The nanoparticles are usually supported on the outer surface of the carbon spheres or other carbon materials, which may block the pore structure on the surface of the carbon spheres and is not favorable for exerting high electrical conductivity of the carbon materials, and the migration rate in the electrolyte is reduced. Further, Fe₃O₄Direct exposure to the electrolyte can destabilize its structure when cycled at high current densities for extended periods of time, resulting in limitations in the improvement of electrochemical performance.

Therefore, it is necessary to construct a novel optimized structure which can make full use of carbon and Fe when used as a supercapacitor electrode material with higher performance₃O₄The nano particles act synergistically to achieve the purpose of better electrochemical energy storage application.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, it is an object of the present invention to provide a composite material, a method for its preparation and use, which solve the problems of the prior art.

In order to achieve the above objects and other related objects, the present invention is achieved by the following technical solutions.

One of the objects of the present invention is to provide a composite material comprising a hollow carbon nanomaterial and Fe₃O₄Nanoparticles, wherein the hollow carbon nanomaterial is in a concave bowl-shaped structure, and Fe is loaded in a concave part of the bowl-shaped structure₃O₄A nanoparticle;

the bowl wall of bowl form structure is hierarchical porous structure, hierarchical porous structure includes macropore, micropore and mesopore, the aperture of macropore is for being > 50nm, the aperture of micropore is for being < 2nm, the aperture of mesopore is 2 ~ 50 nm.

Preferably, the Fe₃O₄No more than 50nm of the nanoparticles.

Preferably, the average particle size of the hollow carbon nanomaterial is 100-300 nm.

Preferably, the specific surface area of the composite material is 300m² g^-1～600m² g^-1。

Preferably, the nitrogen content of the composite material is 3 at% to 5 at%.

Preferably, the oxygen content of the composite material is 5 at% to 18 at%.

Preferably, the composite material has a bulk density of 1g¹cm^-3～2g¹cm^-3。

Preferably, the Fe in the composite material is based on the total mass of the composite material₃O₄The content of (A) is 10 wt% -60 wt%.

The second purpose of the invention is to provide a preparation method of the composite material, which comprises the following steps:

impregnating impregnation liquid containing an iron source onto the hollow carbon nano material by adopting an incipient wetness impregnation method, and then calcining to obtain the composite material.

The application of Fe by incipient wetness impregnation₃O₄The nano particles are uniformly dispersed in the concave part of the hollow carbon nano material with a concave bowl-shaped structure to controllably synthesize Fe with different contents₃O₄And (3) nanoparticles.

Preferably, the iron source is selected from one or more of iron nitrate, iron sulphate and iron trichloride.

More preferably, the iron source comprises a pre-treatment. Specifically, the pretreatment is to disperse an iron source in a medium. The medium is ethanol. More specifically, the mass volume ratio of the iron source to the medium is (0.5-3) g:20 ml.

Preferably, the mass ratio of the hollow carbon nanomaterial to the iron source is 0.5g: (1.5-0.5) g.

Preferably, the temperature of the calcination is 300 ℃ to 400 ℃.

Preferably, the calcination time is 2h to 3 h.

Preferably, the calcination is carried out in a protective atmosphere.

More preferably, the protective atmosphere is selected from inert gas or nitrogen.

Preferably, the number of impregnations is 1-6.

Preferably, the incipient wetness impregnation further comprises drying. Specifically, the drying temperature is 50 ℃ to 100 ℃.

Preferably, the hollow carbon nanomaterial is degassed in a closed container to reach a vacuum state. Specifically, the degassing time is at least 30 min.

Preferably, the preparation method of the hollow carbon nanomaterial comprises the following steps:

SiO₂polymerizing the nanospheres, resorcinol, ethylenediamine and formaldehyde, and then dropwise adding a pore-foaming agent for hydrolysis reaction to obtain a precipitate;

carbonizing and calcining the precipitate;

and etching the calcined product by hydrofluoric acid to obtain the hollow carbon nano material.

More preferably, the SiO₂The particle size of the nanospheres is 200-300 nm.

More preferably, the SiO₂The particle size of the nanosphere can be 200 nm-260 nm, and can also be 240 nm-300 nm.

More preferably, the SiO₂Nanospheres include pretreatment. Specifically, the pretreatment is to treat SiO₂The nanospheres are dispersed in the medium. Specifically, the medium is a mixed solvent formed of water and ethanol. More specifically, the concentration of ethanol in the mixed solvent is 10-90 v/v%. Preferably, the SiO is₂The mass-volume ratio of the nanospheres to the medium is (0.15-0.2) g: 100 ml.

More preferably, the temperature of the polymerization reaction is from 25 ℃ to 45 ℃.

More preferably, the temperature of the polymerization reaction may be 25 to 28 ℃, or 28 to 32 ℃, or 32 to 35 ℃, or 35 to 38 ℃, or 38 to 45 ℃.

More preferably, the SiO₂The mass ratio of the nanospheres to the resorcinol is 0.5: (0.15-0.2).

More preferably, the ratio of the resorcinol, the ethylenediamine and the formaldehyde is (0.15-0.2) g, 0.32ml and (0.225-0.3) ml.

More preferably, the porogen is selected from one or both of tetraethyl orthosilicate and cetyltrimethylammonium bromide.

Further preferably, the porogen comprises a pretreatment. Specifically, the pretreatment is to disperse a pore-foaming agent in a medium. The medium is ethanol. More specifically, the volume ratio of the pore-foaming agent to the medium is 1 (34-133).

More preferably, the porogen is reacted with SiO₂The volume-mass ratio of the nanospheres is (0.1-0.6) ml:0.5 g.

More preferably, the concentration of the hydrofluoric acid is 5 wt% to 15 wt%.

More preferably, the temperature of the hydrolysis reaction is 25 ℃ to 45 ℃.

More preferably, the temperature of the carbonization is 300 ℃ to 400 ℃.

More preferably, the carbonization time is 2-5 h.

More preferably, the calcining temperature is 600-1000 ℃.

More preferably, the calcining time is 2-5 h.

More preferably, the etching time is 8-48 h.

More preferably, the carbonization or calcination is carried out in a protective atmosphere.

The invention also aims to provide the application of the composite material as a drug carrier, an electrode material or an adsorption material.

The fourth object of the present invention is to provide an electrode having a current collector coated with the composite material as described above.

It is a fifth object of the present invention to provide a capacitor including the above-mentioned electrode.

The application relates to the preparation of Fe with a particle size of less than 50nm by incipient wetness impregnation₃O₄The nano particles are uniformly dispersed in the concave part of the bowl-shaped structure of the hollow carbon nano material, and by controlling the times of primary wet impregnation, Fe with different contents can be controllably synthesized in the concave part₃O₄And (3) nanoparticles.

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

1) the preparation process of the composite material is simple, and Fe with different contents can be grown in the concave part of the hollow carbon nano material in the in-situ space limited by the simple vacuum incipient wetness impregnation and heat treatment method₃O₄And (3) nanoparticles.

2) The composite material Fe prepared by the invention₃O₄@ CNB Fe₃O₄The nano-particles have small size, the specific surface area of the composite material is high, and the composite material has the characteristics of hierarchical pore structures of micropores, mesopores and macropores, high stacking density, high nitrogen loading capacity, high oxygen loading capacity and the like.

3) The invention has the advantages of wide raw material source, low synthesis cost, simple equipment and mild reaction condition, and is suitable for large-scale industrial production.

4) The composite material Fe prepared by the invention₃O₄The @ CNB combines the unique advantages of hollow carbon nanomaterials such as good electrical conductivity, high specific surface area and pore volume, multi-level pore distribution and high nitrogen content, and Fe₃O₄The unique pseudocapacitance advantage of the material. Therefore, the electrode and the capacitor prepared from the composite material have high weight specific capacitance, and also have good volume specific capacitance, rate capability and cycling stability.

Drawings

Fig. 1 shows an SEM image of a hollow carbon nanomaterial CNB of example 1 in the present application.

FIG. 2 shows the composite Fe obtained by 1 incipient wetness impregnation of ferric nitrate in the hollow carbon nanomaterial CNB in example 1 of the present application₃O₄SEM picture of @ CNB-1.

FIG. 3 shows that the ethanol solution of ferric nitrate in example 2 of this application is soaked in the hollow carbon nano-material CNB for 3 times in the initial wetting process, and the composite material Fe is obtained₃O₄SEM picture of @ CNB-2.

FIG. 4 shows that the ethanol solution of ferric nitrate in example 3 of this application is immersed in the hollow carbon nanomaterial CNB for 5 times in the incipient wetness method, and the composite material Fe is obtained₃O₄SEM picture of @ CNB-3.

Fig. 5 shows a TEM image of the hollow carbon nanomaterial CNB of example 1 in the present application.

FIG. 6 shows the composite Fe obtained by 1 incipient wetness impregnation of iron nitrate in the hollow carbon nanomaterial CNB in example 1 of the present application₃O₄TEM image of @ CNB-1.

FIG. 7 shows the composite Fe obtained by 3 incipient wetness impregnations of ferric nitrate in the hollow carbon nanomaterial CNB in example 2 of the present application₃O₄TEM image of @ CNB-2.

FIG. 8 shows that the ethanol solution of ferric nitrate in example 3 of this application is immersed in the hollow carbon nanomaterial CNB for 5 times in the incipient wetness method, and the composite material Fe is obtained₃O₄TEM image of @ CNB-3.

FIG. 9 shows the composite material Fe in example 1 of the present application₃O₄Thermogravimetric analysis of @ CNB-1.

FIG. 10 shows the composite material Fe in example 1 of the present application₃O₄The nitrogen adsorption and desorption curve chart of @ CNB-1.

FIG. 11 shows the composite material Fe in example 4 of the present application₃O₄The magnetic saturation graph of @ CNB-4.

Fig. 12 shows hysteresis curves of the electrodes obtained for examples 7, 8 and 9 of the present application.

Fig. 13 is a graph showing constant current charge and discharge curves of the electrodes obtained in examples 7, 8 and 9 of the present application.

Figure 14 shows a graph of the volume specific capacitance and weight specific capacitance of the electrodes obtained for examples 7, 8 and 9 of the present application.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

Before the present embodiments are further described, it is to be understood that the scope of the invention is not limited to the particular embodiments described below; it is also to be understood that the terminology used in the examples is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. Test methods in which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under conditions recommended by the respective manufacturers.

When numerical ranges are given in the examples, it is understood that both endpoints of each of the numerical ranges and any value therebetween can be selected unless the invention otherwise indicated. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In addition to the specific methods, devices, and materials used in the examples, any methods, devices, and materials similar or equivalent to those described in the examples may be used in the practice of the invention in addition to the specific methods, devices, and materials used in the examples, in keeping with the knowledge of one skilled in the art and with the description of the invention.

In the examples described below in the present application, SiO₂The particle size of the nanospheres is 200 nm.

Example 1

In this example, a composite material was prepared, comprising the following steps:

1)0.5g of SiO₂The nanospheres and 100mL of ethanol water solution with the concentration of 10 v/v% form a mixed solution, 0.2g of resorcinol, 0.32mL of ethylenediamine and 0.3mL of formaldehyde are sequentially added dropwise under heating and stirring at 25 ℃, then 0.6mL of tetraethyl orthosilicate is added dropwise, the reaction is continued at 35 ℃ for 24 hours, and precipitates are separated and dried;

carbonizing the precipitate at 300 ℃ for 3h under an inert atmosphere, and then heating to 600 ℃ at a heating rate of 5 ℃/min and calcining for 2 h;

and soaking the calcined product in hydrofluoric acid with the concentration of 5 wt% for 48h to obtain a hollow carbon nano material marked as CNB.

2) The above 0.5g of the hollow carbon nanomaterial CNB was placed in a closed container and degassed for 30min to reach a vacuum state, and then added dropwise to a ferric nitrate solution until incipient wetness impregnation, and dried at 80 ℃. The ferric nitrate solution is formed by dissolving ferric nitrate in ethanol, and the mass volume ratio of the ferric nitrate to the ethanol is 0.5g:20 mL.

3) In N₂Calcining for 2h at 300 ℃ in the atmosphere to obtain a composite material marked as Fe₃O₄@CNB-1。

Fig. 1 is an SEM image of the hollow carbon nanomaterial CNB in example 1.

Fig. 5 is a TEM image of the hollow carbon nanomaterial CNB in example 1. As can be seen from fig. 1 and 5, the hollow carbon nanomaterial CNB prepared by the present application has a bowl-shaped structure, a carbon shell thickness of about 10nm, and good morphology uniformity.

FIG. 2 shows the composite Fe obtained by the initial wet impregnation of ferric nitrate on the hollow carbon nanomaterial CNB in example 1 for 1 time₃O₄SEM picture of @ CNB-1.

FIG. 6 shows the composite Fe obtained by the initial wet impregnation of ferric nitrate on the hollow carbon nanomaterial CNB in example 1 for 1 time₃O₄TEM image of @ CNB-1.

As can be seen from FIGS. 2 and 6, a small amount of Fe₃O₄The nanometer particles are grown in the concave part of the bowl-shaped hollow carbon nanometer material, and Fe₃O₄The particle size of the particles was 50 nm.

FIG. 9 shows the composite material Fe in example 1₃O₄Thermogravimetric analysis of @ CNB-1. As can be seen from FIG. 9, the composite material Fe₃O₄@ CNB-1 Fe₃O₄Is 22.5%, and the bulk density, oxygen content and nitrogen content of the composite material are 1.18g respectively¹cm^-313.7 at% and 4.2 at%.

FIG. 10 shows the composite material Fe in example 1₃O₄The nitrogen desorption curve of @ CNB-1. As can be seen from FIG. 10, the composite material Fe₃O₄Specific surface of @ CNB-1Product 527m² g^-1。

Example 2

1)0.5g of SiO₂The nanospheres and 100mL of 20 v/v% ethanol aqueous solution form a mixed solution, 0.15g of resorcinol, 0.32mL of ethylenediamine and 0.2mL of formaldehyde are sequentially added dropwise under heating and stirring at 45 ℃, then 0.6mL of tetraethyl orthosilicate is added dropwise, the reaction is continued at 25 ℃ for 24 hours, and precipitates are separated and dried;

carbonizing the precipitate at 300 ℃ for 3h under an inert atmosphere, and then heating to 900 ℃ at a heating rate of 5 ℃/min and calcining for 3 h;

and soaking the calcined product in 15 wt% hydrofluoric acid for 12h to obtain a hollow carbon nano material marked as CNB.

2) Placing the 0.5g of the hollow carbon nanomaterial CNB in a closed container, degassing for 30min to reach a vacuum state, then dropwise adding into an ethanol solution of ferric nitrate until incipient wetness impregnation, repeating the impregnation process twice after the ethanol solution is volatilized, and drying at 80 ℃. Wherein the ethanol solution of the ferric nitrate is formed by dissolving ferric nitrate in ethanol, and the mass volume ratio of the ferric nitrate to the ethanol is 1.5g:20 mL.

3) In N₂Calcining for 2h at 300 ℃ in the atmosphere to obtain a composite material marked as Fe₃O₄@CNB-2。

FIG. 3 shows the composite Fe obtained by 3 incipient wetness impregnations of ferric nitrate in the hollow carbon nanomaterial CNB in example 2₃O₄SEM picture of @ CNB-2. As can be seen from FIG. 3, the composite material Fe₃O₄The surface of the @ CNB-2 is smoother, which indicates that the outer surface of the bowl-shaped structure of the composite material does not contain Fe₃O₄And (3) nanoparticles.

FIG. 7 shows Fe obtained by 3 incipient wetness impregnations of ferric nitrate in hollow carbon nanomaterial CNB in example 2₃O₄TEM image of @ CNB-2 composite. As can be seen from FIG. 7, the composite material Fe₃O₄The bowl of @ CNB-2 contains a certain amount of Fe₃O₄Nanoparticles of Fe₃O₄The particle size of the nanoparticles is about 50 nm.

FIG. 9 shows the composite Fe of example 2₃O₄Thermogravimetric analysis of @ CNB-2. As can be seen from FIG. 9, the composite material Fe₃O₄@ CNB-2 Fe₃O₄The content of (B) was 36.6%.

FIG. 10 shows the composite Fe of example 2₃O₄@ CNB-2. As can be seen from FIG. 10, the composite material Fe₃O₄@ CNB-2 has a specific surface area of 467m² g^-1The bulk density, oxygen content and nitrogen content of the composite material were 1.18g, respectively¹cm^-313 at% and 3.6 at%.

Example 3

2) Placing the 0.5g of the hollow carbon nanomaterial CNB in a closed container, degassing for 30min to reach a vacuum state, then dropwise adding into an ethanol solution of ferric nitrate until incipient wetness impregnation, repeating the impregnation process for 5 times after the ethanol solution is volatilized, and drying at 80 ℃. Wherein the ethanol solution of the ferric nitrate is formed by dissolving ferric nitrate in ethanol, and the mass volume ratio of the ferric nitrate to the ethanol is 1.5g:20 mL.

3) In N₂Calcining for 2h at 300 ℃ in the atmosphere to obtain a composite material marked as Fe₃O₄@CNB-3。

FIG. 4 is the hollow carbon nanomaterial of ferric nitrate in example 3Primary wet impregnation of CNB for 5 times to obtain composite Fe₃O₄SEM picture of @ CNB-3. As can be seen from FIG. 4, the composite material Fe₃O₄The surface of the @ CNB-3 is smooth, which indicates that the outer surface of the bowl-shaped hollow carbon nano material contains a small amount of Fe₃O₄Nanoparticles, indicating that the impregnation reached saturation.

FIG. 8 shows the composite Fe obtained by 5 incipient wetness impregnations of ferric nitrate in the hollow carbon nanomaterial CNB in example 3₃O₄TEM image of @ CNB-3. As can be seen from FIG. 8, the composite material Fe₃O₄The bowl of @ CNB-3 contains a certain amount of Fe₃O₄Nanoparticles of Fe₃O₄The particle size of the nanoparticles is about 50 nm.

FIG. 9 shows the composite material Fe in example 3₃O₄Thermogravimetric analysis of @ CNB-3. As can be seen from FIG. 9, the composite material Fe₃O₄@ CNB-3 Fe₃O₄The content of (B) was 57.4%.

FIG. 10 shows the composite material Fe in example 3₃O₄The nitrogen desorption curve of @ CNB-3. As can be seen from FIG. 10, the composite material Fe₃O₄@ CNB-3 has a specific surface area of 375m² g^-1The bulk density, oxygen content and nitrogen content of the composite material were 1.23g, respectively¹cm^-314 at% and 4.2 at%.

Example 4

1)0.5g of SiO₂The nanospheres and 100mL of 20 v/v% ethanol aqueous solution form a mixed solution, 0.15g of resorcinol, 0.32mL of ethylenediamine and 0.2mL of formaldehyde are sequentially added dropwise under heating and stirring at 35 ℃, then 0.4mL of tetraethyl orthosilicate is added dropwise, the reaction is continued at 25 ℃ for 48 hours, and precipitates are separated and dried;

carbonizing the precipitate at 300 ℃ for 3h under an inert atmosphere, and then heating to 600 ℃ at a heating rate of 5 ℃/min and calcining for 3 h;

and soaking the calcined product in 10 wt% hydrofluoric acid for 24h to obtain a hollow carbon nano material marked as CNB.

2) The above 0.5g of the hollow carbon nanomaterial CNB was placed in a closed container and degassed for 30min to reach a vacuum state, and then added dropwise to an ethanol solution of ferric nitrate until incipient wetness impregnation, and dried at 80 ℃. Wherein the ethanol solution of the ferric nitrate is formed by dissolving ferric nitrate in ethanol, and the mass volume ratio of the ferric nitrate to the ethanol is 1.5g:20 mL.

3) In N₂Calcining at 400 ℃ for 3h under the atmosphere to obtain a composite material marked as Fe₃O₄@CNB-4。

Composite material Fe of the embodiment of the application₃O₄The outer surface of @ CNB-4 is relatively smooth, which indicates that the outer surface does not contain Fe₃O₄A nanoparticle; a certain amount of Fe in the bowl₃O₄Nanoparticles of Fe₃O₄The particle size of the nanoparticles is about 50 nm. The bulk density, oxygen content and nitrogen content of the composite material were 1.53g, respectively¹cm^-318 at% and 4.8 at%.

FIG. 11 shows the composite Fe of example 4₃O₄The magnetic saturation graph of @ CNB-4. As can be seen from FIG. 11, the composite material Fe₃O₄@ CNB-4 has certain magnetic properties.

Example 5

1)0.5g of SiO₂The nanospheres and 100mL of 20 v/v% ethanol aqueous solution form a mixed solution, 0.2g of resorcinol, 0.32mL of ethylenediamine and 0.3mL of formaldehyde are sequentially added dropwise under heating and stirring at 45 ℃, then 0.45mL of tetraethyl orthosilicate is added dropwise, the reaction is continued at 25 ℃ for 24 hours, and precipitates are separated and dried;

carbonizing the precipitate at 300 ℃ for 2h under an inert atmosphere, and then heating to 900 ℃ at a heating rate of 5 ℃/min and calcining for 3 h;

and soaking the calcined product in 10 wt% hydrofluoric acid for 12h to obtain a hollow carbon nano material marked as CNB.

2) The above 0.5g of the hollow carbon nanomaterial CNB was placed in a closed container and degassed for 30min to reach a vacuum state, and then added dropwise to an ethanol solution of ferric nitrate until incipient wetness impregnation, and dried at 80 ℃. Wherein the ethanol solution of the ferric nitrate is formed by dissolving ferric nitrate in ethanol, and the mass volume ratio of the ferric nitrate to the ethanol is 3g:20 mL.

3) In N₂Calcining at 400 ℃ for 3h under the atmosphere to obtain a composite material marked as Fe₃O₄@CNB-5。

Composite material Fe₃O₄The surface of @ CNB-5 is relatively smooth, which indicates that the outer surface does not contain Fe₃O₄A nanoparticle; a certain amount of Fe in the bowl₃O₄Nanoparticles of Fe₃O₄The particle size of the nanoparticles is about 50 nm. The bulk density, oxygen content and nitrogen content of the composite material were 1.58g, respectively¹cm^-312 at% and 4 at%.

Example 6

1)2g of SiO₂The nanospheres and 400mL of 30 v/v% ethanol aqueous solution form a mixed solution, 1g of resorcinol, 1.3mL of ethylenediamine and 1.5mL of formaldehyde are sequentially added dropwise under heating and stirring at 40 ℃, 1.5mL of tetraethyl orthosilicate is added dropwise, the reaction is continued at 30 ℃ for 24 hours, and precipitates are separated and dried;

carbonizing the precipitate at 350 ℃ for 1h under an inert atmosphere, and then heating to 900 ℃ at a heating rate of 5 ℃/min and calcining for 3 h;

and soaking the calcined product in 15 wt% hydrofluoric acid for 24h to obtain a hollow carbon nano material marked as CNB.

2) The above 2g of the hollow carbon nanomaterial CNB was placed in a closed container and degassed for 30min to reach a vacuum state, and then added dropwise to an ethanol solution of ferric nitrate until incipient wetness impregnation, and dried at 80 ℃. Wherein the ethanol solution of the ferric nitrate is formed by dissolving ferric nitrate in ethanol, and the mass volume ratio of the ferric nitrate to the ethanol is 12g:80 mL.

3) In N₂Calcining at 400 ℃ for 3h under the atmosphere to obtain a composite material marked as Fe₃O₄@CNB-6。

In this example, bowl-shaped hollow carbon nanomaterial recesses were prepared in batch and filled with Fe₃O₄A nanoparticle composite material. The bulk density, oxygen content and nitrogen content of the composite material were 1.58g, respectively¹cm^-318 at% and 4.6 at%. Prepared Fe₃O₄The size of the nano particles is about 50nm, and the nano particles can better grow in the composite material Fe₃O₄@ CNB-6. The particle size has better particle uniformity and morphology uniformity, and 5-10g of composite material Fe can be prepared in batches₃O₄@CNB-6。

Example 7

In this embodiment, an electrode and a capacitor are provided, which includes the following:

the capacitor comprises an electrode and other necessary components, wherein the electrode is prepared according to the following method: the composite material of example 1, acetylene black and polytetrafluoroethylene were mixed in a mass ratio of 8: 1: 1 to prepare a homogeneous slurry, and then coating the slurry on a nickel foam current collector of 1 × 1cm, and drying at 100 ℃ for 12 hours to prepare a working electrode. The loading of the composite material was about 2.0mg cm^-2。

The Hg/HgO electrode and Pt were used as reference and counter electrodes, respectively. Electrochemical performance was tested on a CHI 660D electrochemical workstation using a three electrode configuration with 6M KOH as the electrolyte.

Example 8

Except that the composite material obtained in example 2 was used to prepare an electrode, the procedure was as in example 7.

Example 9

Except that the composite material obtained in example 3 was used to prepare an electrode, the procedure was as in example 7.

FIG. 12 shows the hysteresis curves of the composites obtained in examples 1, 2 and 3 under a magnetic field of + -30 kOe. As can be seen from the figure, all the composites had no significant hysteresis and exhibited good superparamagnetism. With Fe₃O₄The content in the composite material gradually increased, and the magnetic saturation (Ms) obtained by testing also increased correspondingly. Fe₃O₄@CNB-1，Fe₃O₄@ CNB-2 and Fe₃O₄Magnetic saturation of @ CNB-3 was 17.2emu g, respectively^-1，27.6emu g^-1And 43.3emu g^-1The results show that the prepared composite material has good magnetic property.

Fig. 13 is a constant current charge and discharge graph of the electrodes obtained in examples 7, 8 and 9. As can be seen from fig. 13, all constant current charge and discharge (GCD) curves also show a similar isosceles triangle shape, which indicates the excellent reversibility of the typical supercapacitor behavior and charge and discharge processes.

FIG. 14 is a graph of volume specific capacitance and weight specific capacitance obtained in examples 7, 8 and 9. As can be seen from FIG. 14, when the current density was 0.2Ag^-1Specific sum capacitance of 242F g^-1When compared with the hollow carbon nano material CNB, Fe₃O₄The introduction of the nano-particles leads the composite material Fe₃O₄@ CNB-1, composite Fe₃O₄@ CNB-2 and composite Fe₃O₄Weight specific capacitance C of @ CNB-3_gIncrease to 334F g^-1、466F g^-1And 387F g^-1。

In FIG. 14 Ti₃C₂T_xThe catalysis is derived from the references M.Ghidiu, M.R.Lukatskaya, M.Q.ZHao, Y.Gogotsi, M.W.Barsum, Conductive two-dimensional titanium carbide 'clay' with high volumetric capacity, Nature 516(2014) 78-U171.

BCN/MoS in FIG. 14₂Derived from references A.K. Thakur, M.Majumder, R.B. Choudhury, S.B. Singh, MoS2 floats integrated with bone and nitro-gene-bonded carbon, strike gravimeter and volume capacity performance for superparameter applications, J.Power Source 402(2018)163- "173.

Go/MnO in FIG. 14₂Derived from references X.ZHao, L.L.ZHang, S.Murali, M.D.Stoller, Q.H.ZHang, Y.W.Zhu, et al, Incorporation of a mangase Dioxide with High-Performance Electrochemical catalysts, ACS Nano 6(2012) 5404-.

MoO in FIG. 14₃the/CNTs are from references X.Xiao, Z.H.Peng, C.Chen, C.F.Zhang, M.Beidaghi, Z.H.Yang, et al, freesanding MoO3-x nanobelt/carbon nanotube films for Li-ion intercalation pseudocapacitors,Nano Energy 9(2014)355-363。

RGO in FIG. 14 is derived from the references Z.Shell, D.Ghosh, M.A.Pope, decoating Graphene Oxide with Ionic Liquid Nanodroplets, An Approach to Energy-detect, High-Voltage Supercapacitors, ACS Nano 11(2017) 10077-10087.

Fe in FIG. 14₃O_4/RGO is derived from the references W.H.Khoh, J.D.Hong, Layer-by-Layer self-assembly of inorganic multilayered filters compounded of magnetic/reduced graphene oxide layers for hypercapacitive application, Colloid Surface A436(2013) 104-112.

PIN/CNTs in FIG. 14 are derived from references Z.J.Cai, Q.Zhang, X.Y.Song, Improved Electrochemical Performance of polyimide/Carbon Nanotubes composites as Electrode materials for Supercapacitors, Electron.Mater.Lett.12(2016) 830-840.

The port Carbon in FIG. 14 is derived from the references X.Y.ZHEN, W.Lv, Y.Tao, J.J.Shao, C.ZHang, D.H.Liu, et al, Oriented and Interlinked port Carbon Nanosheets with an expression vector Performance, chem.Mater.26(2014) 6896-.

RGO-F/PANI in FIG. 14 is derived from the references P.P.Yu, X.ZHao, Z.L.Huang, Y.Z.Li, Q.H.Zhang, Free-standing three-dimensional graphene and polyaniline nanowearrays hybrid foams for high-performance flexible and lightweight superparameters, J.Mater.chem.A2(2014) 14413-.

It can also be seen from FIG. 14 that the material is compared with other materials reported previously, such as porous carbon, carbon nanotube, graphene, MXene, MoS₂The composite material prepared by the method has excellent weight specific capacitance and volume specific capacitance.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A composite material comprising a hollow carbon nanomaterial and Fe₃O₄Nanoparticles, wherein the hollow carbon nanomaterial is in a concave bowl-shaped structure, and Fe is loaded in a concave part of the bowl-shaped structure₃O₄A nanoparticle;

the bowl wall of the bowl-shaped structure is of a hierarchical porous structure, the hierarchical porous structure comprises macropores, micropores and mesopores, the pore diameter of the macropores is larger than 50nm, the pore diameter of the micropores is smaller than 2nm, and the pore diameter of the mesopores is 2 nm-50 nm.

2. The composite material of claim 1, wherein the Fe is₃O₄The particle size of the nano-particles is not more than 50 nm;

and/or the average particle size of the hollow carbon nano material is 100-300 nm;

and/or the specific surface area of the composite material is 300m² g-¹～600m² g-¹；

And/or the nitrogen content of the composite material is 3 at% to 5 at%;

and/or the oxygen content of the composite material is 5 at% to 18 at%;

and/or the bulk density of the composite material is 1g¹cm-³～2g¹cm-³；

And/or, based on the total mass of the composite material, Fe in the composite material₃O₄The content of (A) is 10 wt% -60 wt%.

3. A method for preparing a composite material according to claims 1-2, comprising the steps of:

4. The method of claim 3, wherein the iron source is selected from one or more of iron nitrate, iron sulfate, and iron trichloride;

and/or the mass ratio of the hollow carbon nano material to the iron source is 0.5g: (1.5-0.5) g;

and/or, the incipient wetness impregnation is carried out under vacuum conditions.

5. The method of claim 3, wherein the temperature of the calcining is from 300 ℃ to 400 ℃;

and/or the calcining time is 2-5 h;

and/or, the calcining is carried out in a protective atmosphere.

6. The method of claim 3, wherein the hollow carbon nanomaterial is prepared by:

carbonizing and calcining the precipitate;

7. The method of claim 6, wherein the polymerization reaction temperature is from 25 ℃ to 45 ℃;

and/or, the SiO₂The mass ratio of the nanospheres to the resorcinol is 0.5: (0.15 to 0.2);

and/or the mixture ratio of the resorcinol, the ethylenediamine and the formaldehyde is (0.15-0.2) g, 0.32ml and (0.225-0.3) ml;

and/or the pore-foaming agent is selected from one or two of tetraethyl orthosilicate and hexadecyl trimethylamine bromide;

and/or, the porogenic agent and SiO₂Of nanospheresThe volume-mass ratio is (0.1-0.6) ml:0.5 g;

and/or the concentration of the hydrofluoric acid is 5 wt% -15 wt%;

and/or the temperature of the hydrolysis reaction is 25-45 ℃;

and/or the carbonization temperature is 300-400 ℃;

and/or the calcining temperature is 600-1000 ℃;

and/or, the carbonization is carried out in a protective atmosphere;

and/or, the calcining is carried out in a protective atmosphere.

8. Use of the composite material according to any one of claims 1 to 2 as a drug carrier, electrode material or adsorbing material.

9. An electrode having a current collector coated with the composite material according to any one of claims 1 to 2.

10. A capacitor comprising an electrode according to claim 9.