CN110902674B - A kind of preparation method of high-quality graphene oxide - Google Patents

Abstract

The invention discloses a preparation method of high-quality graphene oxide, relates to the technical field of graphene oxide preparation, and aims to provide a preparation method of graphene with high oxidation degree and low defect density. The method mainly comprises the following steps: A. the mixture of the first intercalating agent concentrated sulfuric acid, the second intercalating agent sulfate, the third intercalating agent and the phosphate is diffused and expanded in the squamous graphite at room temperature to form a graphite interlayer compound; B. fully oxidizing the graphite interlayer compound by potassium permanganate at medium temperature, and further adding hydrogen peroxide to obtain a graphene oxide original sample; C. and (3) removing hydrogen peroxide under the condition of heat preservation, and further centrifugally washing to obtain a pure graphene oxide sample. The method disclosed by the invention is simple and easy to operate, low in cost and capable of preparing in a large scale, and the prepared graphene oxide has the advantages of high oxidation degree, low defect density and large and thin sheet layers, so that a reliable source is provided for the large-scale preparation of the reduced graphene.

Description

A kind of preparation method of high-quality graphene oxide

technical field

The invention belongs to the technical field of graphene oxide preparation, in particular to the preparation of high-quality graphene oxide.

Background technique

Graphene oxide has made great progress since it was first synthesized by Brodie in 1859. Especially in 2004, graphene oxide was used as a precursor to obtain reduced graphene by reduction method, which once again promoted the development and application of graphene oxide. At the same time, graphene oxide itself has the characteristics of excellent dispersion, osmotic swelling, insulation, near-infrared absorption, and functional modification, and is widely used in coatings, biomedicine, organic solar cells, detectors, and other fields.

The Hummers method is currently the most commonly used method for preparing graphene oxide, that is, mixing concentrated sulfuric acid and sodium nitrate with graphite, and potassium permanganate as an oxidant. Compared with the previous Brodie method and Saudenmaier method, the Hummers method uses potassium permanganate and sodium nitrate instead of potassium perchlorate and fuming nitric acid, which reduces the experimental risk and toxic gas emissions, but sodium nitrate will still produce a small amount during the oxidation process. Toxic gas nitrogen dioxide. In 2010, based on the Hummers method, Marcano et al. replaced the intercalation agent sodium nitrate with phosphoric acid to prepare graphene oxide, so that no toxic gas was produced during the reaction and the hydrophilicity of graphene oxide was improved. However, the preparation of graphene oxide with higher oxidation degree and lower defect density is still an urgent problem to be solved by scientific researchers.

Contents of the invention

The invention provides a method for preparing high-quality graphene oxide, which is simple and easy to operate, does not require special reaction equipment, and the prepared graphene oxide has the characteristics of high oxidation degree and low defect density.

In order to achieve the above object, the present invention prepares graphene oxide detailed process as follows:

(1) Graphite intercalation compound: Mix concentrated sulfuric acid, the second intercalation agent and the ground third intercalation agent fine powder as the intercalation agent, the molar ratio of sulfate to phosphate is 1:1-25:1, and stir Under the conditions, add scaly graphite powder to expand and foam for 12-48 hours to obtain mixed solution A, and the total mass ratio of graphite powder to intercalation agent is 1:1-1:550;

The second intercalation agent sulfate is one or more of lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, barium sulfate, aluminum sulfate, iron sulfate, sodium bisulfate, and potassium bisulfate; The layer agent is one of lithium phosphate, sodium phosphate, potassium phosphate, magnesium phosphate, zinc phosphate, potassium dihydrogen phosphate, sodium dihydrogen phosphate, lithium dihydrogen phosphate, dipotassium hydrogen phosphate, disodium hydrogen phosphate, dilithium hydrogen phosphate species or several.

(2) Oxidation: Slowly add the oxidant potassium permanganate to the above mixed solution A within 15-45min, the mass ratio of graphite powder to potassium permanganate is 1:1-1:10, raise the temperature to 25-50℃ and stir for reaction 4-10h; then slowly add hydrogen peroxide with a mass concentration of 10-30% dropwise until no more bubbles are generated, and heat up to 50°C for 1-6h to obtain a mixed solution B;

(3) Centrifugal washing: The mixed solution B was sequentially washed with 0.1-2 M hydrochloric acid aqueous solution and deionized water to pH=5-7.4, and the precipitate was freeze-dried to obtain brown-yellow graphene oxide.

Preferably, in the above step (1), the oxidation effect of the mixed system of sulfuric acid/bisulfate and dihydrogen phosphate as an intercalation agent is better.

Preferably, in the above step (2), the medium temperature oxidation temperature is 40°C, and the oxidation effect is better.

Compared with the prior art, the present invention adopts the mixture of concentrated sulfuric acid as the first intercalation agent, sulfate as the second intercalation agent and phosphate as the third intercalation agent, replacing only sulfuric acid/phosphoric acid in the prior art to form graphite The interlayer compound is oxidized, which is more conducive to the diffusion of the intercalation agent between the graphite layers, increasing the graphite expansion distance to form a graphite-sulfuric acid interlayer compound, and the operation is simple and feasible, and the safety is improved; further, in the oxidation process of potassium permanganate In the process, the oxidant diffuses from the edge of the graphite to the center, and forms a ring-shaped manganate with the carbon adjacent to the graphite surface. The manganate is unstable, and it is easy to form carbonyl carbon and holes on the surface of the carbon ring during hydrolysis. The addition of the third intercalation agent is due to Slow hydrolysis releases the phosphate group to protect the C-O bond formed during the hydrolysis of the manganate ester, avoiding the excessive oxidation of the C-O bond to form carbonyl carbon defects, and retaining the integrity of the carbon ring on the surface of graphene oxide as much as possible without affecting the degree of oxidation peeling. In a word, the present invention relates to a method that is simple and easy to operate, low in cost, and can be prepared in large quantities. The prepared graphene oxide has a high degree of oxidation, low defect density, and large and thin graphite sheets.

Description of drawings

Fig. 1 is that the present invention participates in the XRD characterization picture of preparing graphene oxide with different dihydrogen phosphate;

Fig. 2 is that the present invention participates in the Raman spectrum characterization picture of preparing graphene oxide with different dihydrogen phosphate;

Fig. 3 is the TEM picture of the high-quality graphene oxide prepared by a preferred embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, and are not intended to limit the present invention, that is, the described embodiments are only some of the embodiments of the present invention, but not all of the embodiments. The components of the embodiments of the invention generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations.

Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.

It should be noted that relative terms such as the terms "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any relationship between these entities or operations. any such actual relationship or order exists between them. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

The characteristics and performance of the present invention will be described in further detail below in conjunction with the examples.

Example 1

(1) Graphite interlayer compound: Mix 45ml of concentrated sulfuric acid/potassium hydrogensulfate and 11g of ground potassium dihydrogen phosphate fine powder as an intercalation agent, add 0.375g of scaly graphite powder to expand and foam for 24 hours under stirring conditions to obtain a mixed solution A ;

(2) Oxidation: Slowly add 2.25g of potassium permanganate as an oxidizing agent to the mixed solution A within 30 minutes, raise the temperature to 40°C and stir for 6 hours; then slowly add hydrogen peroxide with a mass concentration of 30% until no bubbles are generated. Raise the temperature to 50°C for 3 hours to obtain the mixed solution B;

(3) Centrifugal washing: The mixed solution B was sequentially washed with 1M hydrochloric acid aqueous solution and deionized water to pH=5-6, and the precipitate was freeze-dried to obtain brown-yellow graphene oxide.

Example 2

(1) Graphite interlayer compound: Mix 45ml of concentrated sulfuric acid/potassium hydrogensulfate and 9.75g of ground sodium dihydrogen phosphate fine powder as an intercalation agent, add 0.375g of scaly graphite powder to expand and foam for 24 hours under stirring conditions to obtain a mixed solution A;

(2) Oxidation: Slowly add 2.25g of potassium permanganate as an oxidizing agent to the mixed solution A within 30 minutes, raise the temperature to 40°C and stir for 6 hours; then slowly add hydrogen peroxide with a mass concentration of 30% until no bubbles are generated. Raise the temperature to 50°C for 3 hours to obtain mustard green mixture B;

(3) Centrifugal washing: The mixed solution B was sequentially washed with 1M hydrochloric acid aqueous solution and deionized water to pH=5-6, and the precipitate was freeze-dried to obtain brown-yellow graphene oxide.

Example 3

(1) Graphite interlayer compound: Mix 45ml of concentrated sulfuric acid/potassium hydrogensulfate and 8.45g of ground lithium dihydrogen phosphate fine powder as an intercalation agent, add 0.375g of scaly graphite powder to expand and foam for 24 hours under stirring conditions to obtain a mixed solution A;

(2) Oxidation: Slowly add 2.25g of potassium permanganate as an oxidizing agent to the mixed solution A within 30 minutes, raise the temperature to 40°C and stir for 6 hours; then slowly add hydrogen peroxide with a mass concentration of 30% until no bubbles are generated. Raise the temperature to 50°C for 3 hours to obtain mustard green mixture B;

(3) Centrifugal washing: The mixed solution B was sequentially washed with 1M hydrochloric acid aqueous solution and deionized water to pH=5-6, and the precipitate was freeze-dried to obtain brown-yellow graphene oxide.

As can be seen from Figure 1, the 2θ values of the XRD of the graphene oxide prepared in Example 1, Example 2, and Example 3 are 8.91, 9.38, and 9.43 respectively, while the 2θ values of the graphene oxide prepared in the general literature are between 10- 11, which shows that the oxidation degree of graphene oxide prepared by the present invention is higher, mainly because the intercalation agent has a high diffusion depth in graphite, allowing subsequent potassium permanganate oxidation to proceed from the graphite edge to the center, deepening the oxidation degree and stripping efficiency.

As can be seen from Fig. 2, the _ID /I _G values of the Raman spectrum of the graphene oxide prepared in Example 1, Example 2, and Example 3 are respectively 0.945, 0.935, and 0.914, which shows that dihydrogen phosphate prepares graphite oxide Alkenes have a high degree of oxidation and a low defect density.

It can be seen from Figure 3 that the graphene oxide prepared in Example 1 has the characteristics of large and thin sheets.

Those skilled in the art will appreciate that the embodiments described here are to help readers understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical revelations disclosed in the present invention without departing from the essence of the present invention, and these modifications and combinations are still within the protection scope of the present invention.

Claims (3)

1. a preparation method of high-quality graphene oxide, characterized in that the following steps: Step 1: Graphite intercalation compound: at room temperature, use concentrated sulfuric acid as the first intercalation agent, add sulfate and phosphate as the second and third intercalation agents respectively, and the molar ratio of sulfate to phosphate is 1:1-25 : 1, adding scaly graphite powder under stirring conditions to expand and foam for 12-48h to obtain mixed solution A, the mass ratio of graphite powder to intercalant is 1:1-1:550; Step 2: Oxidation: Slowly add the oxidant potassium permanganate to the above mixed solution A within 15-45 minutes, the mass ratio of graphite powder to potassium permanganate is 1:1-1:10, raise the temperature to 25-50°C and stir to react 4-10h; then slowly add hydrogen peroxide with a mass concentration of 10-30% dropwise until no more bubbles are generated, and heat up to 50°C for 1-6h to obtain a mixed solution B; Step 3: Centrifugal washing: The mixed solution B was sequentially washed with 0.1-2M hydrochloric acid aqueous solution and deionized water to pH=5.0-7.4, and the precipitate was freeze-dried to obtain graphene oxide. 2. the preparation method of a kind of high-quality graphene oxide according to claim 1 is characterized in that: the second above-mentioned intercalation agent sulfate is lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, barium sulfate, sulfuric acid One or more of aluminum, iron sulfate, sodium hydrogen sulfate, and potassium hydrogen sulfate. 3. the preparation method of a kind of high-quality graphene oxide according to claim 1 is characterized in that: above-mentioned the 3rd intercalation agent is lithium phosphate, sodium phosphate, potassium phosphate, magnesium phosphate, zinc phosphate, dihydrogen phosphate One or more of potassium, sodium dihydrogen phosphate, lithium dihydrogen phosphate, dipotassium hydrogen phosphate, disodium hydrogen phosphate, and dilithium hydrogen phosphate.

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