CN103295756B - A kind of preparation method of magnetic nitrogen-doped carbon material - Google Patents

Abstract

The invention provides a method for preparing a magnetic nitrogen-doped carbon material. The method is to adjust the pH of a mixed solvent of absolute ethanol and deionized water to 1 to 3 with concentrated hydrochloric acid, and then oxidize and carbonize the carbonizing agent ( Ferric chloride hexahydrate), carbon source (sugars), nitrogen source (glycine or melamine) are fully dissolved or dispersed in a mixed solvent, stirred and mixed evenly, then evaporated to remove the solvent, and carbonized at 60°C~80°C for 40~50h , The carbonized product is ground and then carbonized at 180-200°C for 4-6 hours to obtain magnetic nitrogen-doped carbon materials, which have good application prospects in fuel cell catalysts and supercapacitors. The invention has mild reaction conditions, low cost and simple operation, and the nitrogen content in the nitrogen-doped carbon material is easy to control.

Description

A kind of preparation method of magnetic nitrogen-doped carbon material

technical field

The invention belongs to the technical field of carbon materials, and relates to a method for preparing a nitrogen-doped carbon material, in particular to a method for preparing a magnetic nitrogen-doped carbon material.

Background technique

Carbon is the most important constituent element of all organisms on earth. The different bonding methods between carbon atoms lead to the formation of a variety of carbon materials in different forms, including soft and creamy graphite with a common layered structure, and precious hard diamond with a tetrahedral structure. Carbon materials are widely used in metallurgy, chemical industry, machinery, electricity, aviation and other fields due to their excellent heat resistance, high thermal conductivity, good chemical inertness, and high electrical conductivity. In recent years, carbon materials have also received great attention in the field of electrochemical applications, especially in the application of fuel cell catalysts. Adding nitrogen to the carbon material can significantly improve the oxygen reduction activity of the carbon material. Studies have shown that the properties of nitrogen-doped carbon materials are directly related to the amount of nitrogen doped. High-temperature pyrolysis of nitrogen-containing precursors is one of the most convenient methods to obtain nitrogen-doped carbon materials. However, due to the restriction of the nitrogen content in the precursor, it is difficult to control the nitrogen doping amount.

Contents of the invention

The object of the present invention is to provide a method for preparing magnetic nitrogen-doped carbon material in order to solve the problems existing in the prior art.

The preparation method of the magnetic nitrogen-doped carbon material of the present invention, after adjusting the pH of the mixed solvent of ethanol and deionized water to 1-3 with concentrated hydrochloric acid, fully dissolves or disperses the oxidative carbonization agent, carbon source and nitrogen source in sequence under stirring Stir and mix evenly in a mixed solvent, then evaporate the solvent, carbonize at 60°C~80°C for 40~50h, carbonize the product after grinding, and then carbonize at 180~200°C for 3~6h to obtain a magnetic nitrogen-doped carbon material .

The carbon source is sugar (such as sucrose, glucose, starch, cellulose, etc.); the nitrogen source is glycine or melamine; the oxidative carbonizing agent is ferric chloride hexahydrate.

In the mixed solvent, the volume ratio of ethanol to deionized water is 1:1-1:2.

The mass ratio of the nitrogen source to the carbon source is 1:10-1:50.

The mass ratio of the oxidizing carbonizing agent to the carbon source is 1:2 to 1:3.

The evaporation of the solvent is carried out in a blast oven at 60-70°C.

Figure 1 is the Raman spectrum of the primary carbonization product of the present invention, which is compared with C powder (XC-72). It can be seen from Figure 1 that the nitrogen-doped carbon material has begun to form a G peak, but it is very irregular, indicating that only a small part of the carbon source and nitrogen source is carbonized.

Figure 2 is the Raman spectrum of the magnetic nitrogen-doped carbon material prepared by the present invention, and it is compared with C powder (XC-72). As can be seen from Figure 2, the D peak and G peak of the nitrogen-doped carbon material prepared by the present invention are very obvious, and the G peak is obviously higher than the D peak, indicating that the carbon material formed has a relatively high degree of graphitization, and the carbon source and The nitrogen source is basically completely carbonized.

Fig. 3 is an X-ray diffraction spectrum of the nitrogen-doped carbon material prepared in the present invention. The test condition is 40kV, 30mA, using Cu target ray tube. It can be seen from Figure 3 that there is an obvious carbon characteristic peak at 2θ=24.8 degrees, indicating that the carbon source and nitrogen source have been carbonized, and it also shows the characteristic peak of ferric oxide, indicating that during the formation of nitrogen-carbon materials , a part of Fe ³⁺ still exists in the carbon material in the form of ferric oxide.

Fig. 4 is a picture of the magnetic test of the nitrogen-doped carbon material prepared by the present invention using a permanent magnet. Figure 4A shows that the nitrogen-doped carbon material is placed in the sample bottle under the condition of no permanent magnet, and the nitrogen-doped carbon material is naturally placed at the bottom of the sample bottle; Figure 4B is a permanent magnet placed next to the sample bottle , it is found that the nitrogen-doped carbon materials prepared by the present invention are all close to the permanent magnet side, indicating that the nitrogen-doped carbon materials prepared by the present invention are magnetic. This shows that during the formation of nitrogen-doped carbon materials, a part of Fe ³⁺ is transformed into Fe or ferric oxide and exhibits ferromagnetism.

After testing, the nitrogen content of the magnetic nitrogen-doped carbon material prepared by the present invention is 0.9%-12.5%.

The present invention has the following advantages relative to the prior art:

1. Sugars such as sucrose are used as carbon sources, which are renewable resources with low cost;

2. Using glycine or melamine as nitrogen source, no pollution, green and environmental protection.

3. Ferric chloride hexahydrate is used as the oxidative carbonization agent to realize the oxidative carbonization of carbon source and nitrogen source at a relatively low temperature. The reaction conditions are mild, the cost is low, and it is easy to operate and control. At the same time, it ensures the nitrogen-doped carbon material magnetic;

4. The nitrogen content in nitrogen-doped carbon materials can be controlled by adjusting the ratio of carbon source and nitrogen source.

5. The nitrogen-doped carbon material prepared by the present invention is magnetic and easy to separate.

Description of drawings

Fig. 1 is the Raman spectrogram of primary carbonization product in the present invention preparation carbon material process;

Fig. 2 is the Raman spectrogram of the nitrogen-doped carbon material prepared by the present invention;

Fig. 3 is the X-ray diffraction spectrogram of the nitrogen-doped carbon material prepared by the present invention;

Fig. 4 is a magnetic test diagram of the nitrogen-doped carbon material prepared in the present invention.

detailed description

The preparation of the magnetic nitrogen-doped carbon material of the present invention will be further illustrated by specific examples below.

Example 1

(1) Mix absolute ethanol and deionized water at a volume ratio of 1:1 to form a mixed solvent of 40mL, and adjust the pH of the solution to 2 with concentrated hydrochloric acid;

(2) Add 0.60g ferric chloride hexahydrate (FeCl ₃ 6H ₂ O) and 1.50g sucrose to the mixed solvent in turn, and stir for 20 minutes;

(3) Add 0.033g glycine to the mixed solvent and stir for 0.5 hours;

(4) Put the mixed system in a blast oven, evaporate the solvent at 60°C, and then carbonize at 80°C for 40 hours to obtain a carbonized product;

(5) After the primary carbonization product is ground, it is placed in a blast oven and carbonized at 200°C for 4 hours to obtain a magnetic nitrogen-doped carbon material. The nitrogen content of the nitrogen-doped carbon material is 0.93%.

Example 2

(1) Mix absolute ethanol and deionized water at a volume ratio of 1:1.5 to form a mixed solvent of 40mL, and adjust the pH of the solution to 1 with concentrated hydrochloric acid;

(2) Add 0.60g of ferric chloride hexahydrate (FeCl ₃ 6H ₂ O) and 1.20g of glucose into the mixed solvent in turn, and stir for 20 minutes;

(3) Add 0.062g glycine to the mixed solvent and stir for 0.5 hours;

(4) Put the mixed system in a blast oven, evaporate the solvent at 70°C, and then carbonize at 60°C for 40 hours to obtain a carbonized product;

(5) After the primary carbonization product is ground, it is placed in a blast oven and carbonized at 190°C for 6 hours to obtain a magnetic nitrogen-doped carbon material. The nitrogen content of the nitrogen-doped carbon material was 2.1%.

Example 3

(1) Mix absolute ethanol and deionized water at a volume ratio of 1:2 to form a mixed solvent of 40mL, and adjust the pH of the solution to 2 with concentrated hydrochloric acid;

(2) Add 0.60g of ferric chloride hexahydrate (FeCl ₃ 6H ₂ O) and 1.80g of cornstarch into the mixed solvent in turn, and stir for 20 minutes;

(3) Add 0.167g glycine to the mixed solvent and stir for 0.5 hours;

(4) Put the mixed system in a blast oven, evaporate the solvent at 65°C, and then carbonize at 80°C for 48 hours to obtain a carbonized product;

(5) After the primary carbonization product is ground, it is placed in a blast oven and carbonized at 190°C for 6 hours to obtain a magnetic nitrogen-doped carbon material. The nitrogen content of the nitrogen-doped carbon material was 3.2%.

Example 4

(1) Mix absolute ethanol and deionized water at a volume ratio of 1:1.5 to form a mixed solvent of 40mL, and adjust the pH of the solution to 3 with concentrated hydrochloric acid;

(2) Add 0.60g ferric chloride hexahydrate (FeCl ₃ 6H ₂ O) and 1.50g sucrose to the mixed solvent in turn, and stir for 20 minutes;

(3) Add 0.092g of melamine into the mixed solvent and stir for 0.5 hours;

(4) Put the mixed system in a blast oven, evaporate the solvent at 70°C, and then carbonize at 70°C for 45 hours to obtain a carbonized product;

(5) After the primary carbonization product is ground, it is placed in a blast oven and carbonized at 180°C for 5 hours to obtain a magnetic nitrogen-doped carbon material. The nitrogen content of the nitrogen-doped carbon material was 8.6%.

Example 5

(1) Mix absolute ethanol and deionized water at a volume ratio of 1:2 to form a mixed solvent of 40mL, and adjust the pH of the solution to 1 with concentrated hydrochloric acid;

(2) Add 0.60g of ferric chloride hexahydrate (FeCl ₃ 6H ₂ O) and 1.20g of glucose into the mixed solvent in turn, and stir for 20 minutes;

(3) Add 0.093g of melamine into the mixed solvent and stir for 0.5 hours;

(4) Put the mixed system in a blast oven, evaporate the solvent at 65°C, and then carbonize at 60°C for 48 hours to obtain a carbonized product;

(5) After the primary carbonization product is ground, it is placed in a blast oven and carbonized at 185°C for 4 hours to obtain a magnetic nitrogen-doped carbon material. The nitrogen content of this nitrogen-doped carbon material was 10.9%.

Example 6

(1) Mix absolute ethanol and deionized water at a volume ratio of 1:1 to form a mixed solvent of 40mL, and adjust the pH of the solution to 2 with concentrated hydrochloric acid;

(2) Add 0.60g of ferric chloride hexahydrate (FeCl ₃ 6H ₂ O) and 1.80g of cornstarch into the mixed solvent in turn, and stir for 20 minutes;

(3) Add 0.140g of melamine into the mixed solvent and stir for 0.5 hours;

(4) Put the mixed system in a blast oven, evaporate the solvent at 60°C, and then carbonize at 80°C for 50 hours to obtain a carbonized product;

(5) After the primary carbonization product is ground, it is placed in a blast oven and carbonized at 185°C for 6 hours to obtain a magnetic nitrogen-doped carbon material. The nitrogen content of this nitrogen-doped carbon material was 10.4%.

Claims (4)

1. the preparation method of a magnetic nitrogen-doped carbon material, the mixed solvent of absolute ethyl alcohol and deionized water is adjusted behind pH to 1 ~ 3 with concentrated hydrochloric acid, under agitation successively carbonoxide agent, carbon source, nitrogenous source are fully dissolved or dispersed in mixed solvent and are uniformly mixed, then boil off solvent, carbonization 40 ~ 50h at 60 DEG C ~ 80 DEG C, carbonized product is carbonization 4 ~ 6h at 180 ~ 200 DEG C again after grinding, and obtains magnetic nitrogen-doped carbon material;

A described carbonization, secondary carbonization are all carried out in convection oven;

Described carbon source is carbohydrate; Described nitrogenous source is glycine or melamine; The mass ratio of described nitrogenous source and carbon source is 1:10 ~ 1:50; Described carbonoxide agent is Iron(III) chloride hexahydrate; The mass ratio of described carbonoxide agent and carbon source is 1:2 ~ 1:3.

2. the preparation method of magnetic nitrogen-doped carbon material as claimed in claim 1, is characterized in that: in described mixed solvent, the volume ratio of absolute ethyl alcohol and deionized water is 1:1 ~ 1:2.

3. the preparation method of magnetic nitrogen-doped carbon material as claimed in claim 1, is characterized in that: described carbohydrate is sucrose, glucose, starch, cellulose.

4. the preparation method of magnetic nitrogen-doped carbon material as claimed in claim 1, is characterized in that: described in to boil off solvent be in convection oven, at 60 ~ 70 DEG C, carry out.