CN110127660B

CN110127660B - Method for preparing porous carbon nanomaterial by microwaves

Info

Publication number: CN110127660B
Application number: CN201910378231.9A
Authority: CN
Inventors: 张旺; 金铉镇; 朴元哲; 刁国旺; 孔玉玉; 王佳民
Original assignee: Yangzhou University
Current assignee: Yangzhou University
Priority date: 2019-05-08
Filing date: 2019-05-08
Publication date: 2023-08-08
Anticipated expiration: 2039-05-08
Also published as: ZA202002472B; CN110127660A

Abstract

The invention discloses a method for preparing a porous carbon nanomaterial by microwaves. The method comprises the steps of taking a mixture of carbon powder and toluene with a mass ratio of 1:1 as a microwave reactant, mixing the microwave reactant and potassium citrate with a mass ratio of 1:10-200, grinding, and then placing the mixture under 200-800W for microwave heating to prepare the porous carbon nanomaterial. The method is simple, convenient and efficient, has low cost, and the prepared porous carbon nanomaterial has higher specific surface area and specific capacitance and can be used as a high-performance supercapacitor material.

Description

Method for preparing porous carbon nanomaterial by microwaves

Technical Field

The invention relates to the technical field of carbon material preparation, in particular to a method for preparing a porous carbon nanomaterial by microwaves.

Background

The porous carbon material has the characteristics of controllable pore canal structure, good electric conductivity and thermal conductivity, adjustable surface component and the like, can be used as an excellent electrode material and is applied to lithium ion batteries and supercapacitors. The preparation of the porous carbon material is mainly formed by high-temperature treatment of a carbon-containing precursor raw material under the protection of an inert atmosphere, and the morphology, the pore diameter structure and the surface components of the carbon material are regulated and controlled by selecting the types and various activation modes of the precursor. In addition to the high-temperature activation of the synthesized carbon material, some auxiliary agents such as water vapor and CO are added in the material activation process ₂ 、KOH、ZnCl ₂ Etc. Although the porous carbon material with high pore size distribution and high specific surface area can be obtained by the method, the energy consumption is high, the yield is low, secondary pollution is generated in post-treatment, and the method is unfavorable for energy conservation and environmental protection.

As a novel heating method, the microwave reaction method has the advantages of high heating rate, high reaction degree, energy conservation, environmental protection and the like. The Voiry research group adopts a method of combining domestic microwave oven preheating treatment and microwave reduction (Science, 2016,353,1413), and the prepared grapheme has high carbon group content and small surface defect number. The instantaneous high heat generated by the microwaves can enable the graphene oxide to be subjected to deep deoxidation and promote recombination of carbon atoms so as to reduce defects. However, pretreatment requires a long period of conventional heating to pre-reduce graphene oxide. In the chinese patent application CN108258240a, although a microwave-assisted experiment is adopted, only a mixture is synthesized by using microwaves, and then high-temperature calcination is required to prepare the hollow carbon sphere with a porous structure, so that the experimental steps are complicated, the time is long, and the cost is high.

Disclosure of Invention

The invention aims to provide a method for preparing a porous carbon nanomaterial by microwaves, which is used for rapid and efficient synthesis and has high specific surface area and high specific capacitance, and solves the problems of long reaction time, high energy consumption and high production cost in the prior art.

The technical scheme for realizing the purpose of the invention is as follows:

the method for preparing the porous carbon nanomaterial by microwaves comprises the following specific steps:

taking a mixture of carbon powder and toluene with the mass ratio of 1:1 as a microwave reactant, mixing the microwave reactant and potassium citrate with the mass ratio of 1:10-200, grinding, then placing the mixture under the microwave heating of 200-800W, naturally cooling, washing, decompressing, filtering and drying to obtain the porous carbon nanomaterial.

The carbon powder is selected from graphite, acetylene black or activated carbon.

Preferably, the mass ratio of the microwave reactant to the potassium citrate is 1: 100-200.

Preferably, the grinding time is 10-20 min, the microwave heating time is 60-600 s, and the energy consumption can be reduced while the full reaction of the raw materials is ensured.

Preferably, the washing is to sequentially adopt 10-50% of dilute hydrochloric acid and water for washing to remove impurities.

Preferably, the drying temperature is 50-100 ℃, and the temperature can not only enable the porous carbon nano material to be sufficiently dried, but also prevent the surface of the porous carbon nano material from being oxidized.

Compared with the prior art, the invention has the following advantages:

the method is simple and easy to implement, has short reaction time, does not need a large-scale high-energy-consumption heating device, takes potassium citrate as a carbon source, is green and environment-friendly, has low cost, and the prepared porous carbon nanomaterial has stable physical and chemical properties and higher specific surface area and specific capacitance.

Drawings

FIG. 1 is a scanning electron microscope image of the material prepared in example 1.

FIG. 2 is a graph showing the cyclic voltammogram (a) and the charge-discharge curve (b) of the material prepared in example 1.

FIG. 3 is a graph of (a) cyclic voltammograms and (b) charge and discharge curves of the materials prepared in example 2.

FIG. 4 is a graph showing the cyclic voltammogram (a) and the charge-discharge curve (b) of the material prepared in example 3.

FIG. 5 is a graph showing the cyclic voltammogram (a) and the charge-discharge curve (b) of the material prepared in comparative example 1.

FIG. 6 is a graph showing the cyclic voltammogram (a) and the charge-discharge curve (b) of the material prepared in comparative example 2.

Detailed Description

The invention is further described in detail below with reference to examples and figures.

Example 1

Weighing 0.01g of a microwave reactant and 1g of potassium citrate, wherein the microwave reactant is a mixture of graphite and toluene, the mass ratio is 1:1, mixing the microwave reactant and the potassium citrate in a mortar, fully grinding for 10 minutes, and then placing the mixture in a microwave reactor for microwave heating, wherein the reaction power is 600W, and the reaction time is 300s. And after the product is naturally cooled, washing the product with 1mol/L hydrochloric acid and water to remove impurities, carrying out vacuum filtration and drying in a 60 ℃ oven to obtain the porous carbon nanomaterial. Its specific surface area is 1200m ² /g。

Example 2

Weighing 0.01g of a microwave reactant and 0.1g of potassium citrate, wherein the microwave reactant is a mixture of graphite and toluene, the mass ratio is 1:1, mixing the microwave reactant and the potassium citrate in a mortar, fully grinding for 10 minutes, and then placing the mixture in a microwave reactor for microwave heating, wherein the reaction power is 600W, and the reaction time is 300s. And after the product is naturally cooled, washing the product with 1mol/L hydrochloric acid and water to remove impurities, carrying out vacuum filtration and drying in a 60 ℃ oven to obtain the porous carbon nanomaterial.

Example 3

Weighing 0.01g of a microwave reactant and 2g of potassium citrate, wherein the microwave reactant is a mixture of graphite and toluene, the mass ratio is 1:1, mixing the microwave reactant and the potassium citrate in a mortar, fully grinding for 10 minutes, and then placing the mixture in a microwave reactor for microwave heating, wherein the reaction power is 600W, and the reaction time is 300s. And after the product is naturally cooled, washing the product with 1mol/L hydrochloric acid and water to remove impurities, carrying out vacuum filtration and drying in a 60 ℃ oven to obtain the porous carbon nanomaterial.

Comparative example 1

Weighing 0.01g of a microwave reactant and 0.09g of potassium citrate, wherein the microwave reactant is a mixture of graphite and toluene, the mass ratio is 1:1, mixing the microwave reactant and the potassium citrate in a mortar, fully grinding for 10 minutes, and then placing the mixture in a microwave reactor for microwave heating, wherein the reaction power is 600W, and the reaction time is 300s. And after the product is naturally cooled, washing the product with 1mol/L hydrochloric acid and water to remove impurities, carrying out vacuum filtration and drying in a 60 ℃ oven to obtain the porous carbon nanomaterial.

Comparative example 2

Weighing 0.01g of a microwave reactant and 2.1g of potassium citrate, wherein the microwave reactant is a mixture of graphite and toluene, the mass ratio is 1:1, mixing the microwave reactant and the potassium citrate in a mortar, fully grinding for 10 minutes, and then placing the mixture in a microwave reactor for microwave heating, wherein the reaction power is 600W, and the reaction time is 300s. And after the product is naturally cooled, washing the product with 1mol/L hydrochloric acid and water to remove impurities, carrying out vacuum filtration and drying in a 60 ℃ oven to obtain the porous carbon nanomaterial.

FIG. 1 is a scanning electron microscope image of the material prepared in example 1, from which it can be seen that the nitrogen-doped carbon nanoplatelets have a porous structure with a pore size of about 0.4 μm and a wall thickness of about 30 nm.

FIG. 2 shows (a) cyclic voltammogram and (b) charge-discharge curve of the material prepared in example 1, from which it is understood that the specific capacitance of the material prepared in example 1 is 318F/g, and the specific capacitance is high.

FIG. 3 shows (a) cyclic voltammogram and (b) charge-discharge curve of the material prepared in example 2, from which the specific capacitance of the material prepared in example 2 was 186.2F/g.

FIG. 4 shows (a) cyclic voltammogram and (b) charge-discharge curve of the material prepared in example 3, from which the specific capacitance of the material prepared in example 3 was 259F/g.

FIG. 5 shows (a) cyclic voltammogram and (b) charge-discharge curve of the material prepared in comparative example 1, from which it is seen that the specific capacitance of the material prepared in comparative example 1 is 30F/g, and that it has a low specific capacitance.

FIG. 6 shows (a) cyclic voltammogram and (b) charge-discharge curve of the material prepared in comparative example 2, from which it is seen that the specific capacitance of the material prepared in comparative example 2 is 176F/g, and has a low specific capacitance.

Claims

1. The method for preparing the porous carbon nanomaterial by microwaves is characterized by comprising the following specific steps:

the mass ratio is 1:1, the mixture of carbon powder and toluene is a microwave reactant, and the mass ratio is 1: 10-200, mixing a microwave reactant and potassium citrate, grinding, then placing under 200-800W for microwave heating, naturally cooling, washing, decompressing, filtering and drying after the reaction is finished to obtain the porous carbon nanomaterial; the microwave heating time is 60s; the carbon powder is selected from graphite, acetylene black or activated carbon.

2. The method according to claim 1, wherein the mass ratio of the microwave reactant to the potassium citrate is 1: 100-200.

3. The method of claim 1, wherein the milling time is 10 to 20 minutes.

4. The method according to claim 1, wherein the washing is performed by sequentially using 10-50% of dilute hydrochloric acid and water to remove impurities.

5. The method of claim 1, wherein the drying temperature is 50 to 100 ℃.