阅读说明：本技术 氧化石墨烯表面官能团的可逆调控方法 (Reversible regulation and control method for graphene oxide surface functional group ) 是由 张小廷 沈伟 曹建苹 陈韵吉 于 2020-07-09 设计创作，主要内容包括：本发明提供一种氧化石墨烯表面官能团的可逆调控方法,包括：S1：提供氧化石墨烯分散液,并向氧化石墨烯分散液中加入过渡金属盐,得到混合液；S2：向混合液中加入强碱溶液,于第一温度搅拌第一时间后,升温至第二温度搅拌第二时间进行反应,得到去除官能团的氧化石墨烯；S3：将去除官能团的氧化石墨烯置于强酸溶液中进行酸处理,得到恢复官能团的氧化石墨烯；其中,通过依次重复步骤S1、步骤S2和步骤S3,以实现氧化石墨烯表面官能团的可逆调控。本发明的方法操作简便,成本低,可实现石墨烯在导电开关领域的扩展应用。(The invention provides a reversible regulation and control method of graphene oxide surface functional groups, which comprises the following steps: s1: providing a graphene oxide dispersion liquid, and adding a transition metal salt into the graphene oxide dispersion liquid to obtain a mixed liquid; s2: adding a strong alkali solution into the mixed solution, stirring the mixed solution at a first temperature for a first time, heating the mixed solution to a second temperature, and stirring the mixed solution for a second time to react to obtain graphene oxide with the functional groups removed; s3: placing the graphene oxide with the functional group removed in a strong acid solution for acid treatment to obtain graphene oxide with recovered functional group; wherein, reversible regulation of the graphene oxide surface functional group is realized by sequentially repeating the steps S1, S2 and S3. The method is simple and convenient to operate and low in cost, and can realize the expanded application of the graphene in the field of conductive switches.)

1. A reversible regulation and control method of graphene oxide surface functional groups is characterized by comprising the following steps:

s1: providing graphene oxide dispersion liquid, and adding transition metal salt into the graphene oxide dispersion liquid to obtain mixed liquid;

s2: adding a strong alkali solution into the mixed solution, stirring the mixed solution at a first temperature for a first time, heating the mixed solution to a second temperature, and stirring the mixed solution for a second time to react to obtain graphene oxide with the functional groups removed;

s3: placing the graphene oxide with the functional group removed in a strong acid solution for acid treatment to obtain graphene oxide with a recovered functional group;

wherein the reversible regulation of the graphene oxide surface functional group is realized by sequentially repeating the steps S1, S2 and S3.

2. The method of claim 1, wherein the transition metal salt is selected from one or more of transition metal sulfate selected from one or more of iron sulfate, cobalt sulfate, nickel sulfate, copper sulfate, and manganese sulfate, transition metal nitrate selected from one or more of iron nitrate, cobalt nitrate, nickel nitrate, copper nitrate, and manganese nitrate, and transition metal chloride selected from one or more of iron chloride, cobalt chloride, nickel chloride, copper chloride, and manganese chloride.

3. The method of claim 1, wherein the first temperature is 20 ℃ to 60 ℃ and the second temperature is 50 ℃ to 80 ℃.

4. The method of claim 1, wherein the first time is between 0.5h and 24h and the second time is between 0.5h and 24 h.

5. The method according to claim 1, wherein the acid treatment time is 0.5 to 8 hours.

6. The method according to claim 1, further comprising adding the transition metal salt in step S1 and then performing ultrasonic treatment for 1min to 60min to obtain the mixed solution.

7. The method according to claim 6, further comprising stirring for 1-60 min after the ultrasonic treatment to obtain the mixed solution.

8. The method as claimed in claim 1, wherein the strong alkali solution is selected from one or more of sodium hydroxide solution and potassium hydroxide solution, and the concentration of the strong alkali solution is 0.01M-10M.

9. The method according to claim 1, wherein the strong acid solution is selected from one or more of hydrochloric acid solution and sulfuric acid solution, and the concentration of the strong acid solution is 0.01M-10M.

10. The method according to claim 1, wherein the mass ratio of the graphene oxide to the transition metal salt is 1: 5-1: 20, the mass ratio of the transition metal salt to the strong base is 5: 1-1: 1, and the mass ratio of the strong base to the strong acid is 1: 1-5: 1.

Technical Field

The invention relates to the field of graphene, in particular to a reversible regulation and control method of graphene oxide surface functional groups.

Background

Graphene has received wide attention from scientists worldwide since its discovery in 2004 by AndreGeim at manchester university in england and his student konstantin novoseov, especially after acquiring the nobel prize in 2010, a research trend of graphene was raised.

As an important derivative of graphene, graphene oxide contains a large number of functional groups on its surface, including hydroxyl, carboxyl, epoxy, and the like. The type and number of the functional groups can greatly influence the properties of the graphene oxide, and further influence the application of the graphene oxide in various fields. On the one hand, the presence of functional groups destroys the sp of perfect graphene²The structure greatly reduces the performances of electric conduction, heat conduction and the like of the graphene; on the other hand, the existence of the functional group can provide more reactive sites, so that the graphene oxide is more reactive, and can have more compact interaction when being compounded with other materials. It is also due to the close interaction between graphene oxide and other materials that the reaction (or removal) of functional groups is generally permanent.

Graphene has very excellent conductivity, and graphene oxide containing functional groups is an insulator, so graphene can be designed as a conductive switch based on the difference in conductivity caused by the number and the type of the functional groups. When graphene is used as a conductive switch, the functional group on the surface of graphene oxide is required to be reversibly transformed. Therefore, a reversible regulation method of graphene oxide surface functional groups is needed.

It is noted that the information disclosed in the foregoing background section is only for enhancement of background understanding of the invention and therefore it may contain information that does not constitute prior art that is already known to a person of ordinary skill in the art.

Disclosure of Invention

The main purpose of the present invention is to overcome at least one of the above drawbacks of the prior art, and to provide a reversible control method for graphene oxide surface functional groups, which can realize the extended application of graphene in the field of conductive switches.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a reversible regulation and control method of graphene oxide surface functional groups, which comprises the following steps: s1: providing a graphene oxide dispersion liquid, and adding a transition metal salt into the graphene oxide dispersion liquid to obtain a mixed liquid; s2: adding a strong alkali solution into the mixed solution, stirring the mixed solution at a first temperature for a first time, heating the mixed solution to a second temperature, and stirring the mixed solution for a second time to react to obtain graphene oxide with the functional groups removed; s3: placing the graphene oxide with the functional group removed in a strong acid solution for acid treatment to obtain graphene oxide with recovered functional group; wherein, reversible regulation of the graphene oxide surface functional group is realized by sequentially repeating the steps S1, S2 and S3.

According to an embodiment of the present invention, the transition metal salt is selected from one or more of transition metal sulfate selected from one or more of iron sulfate, cobalt sulfate, nickel sulfate, copper sulfate, and manganese sulfate, the transition metal nitrate is selected from one or more of iron nitrate, cobalt nitrate, nickel nitrate, copper nitrate, and manganese nitrate, and the transition metal chloride is selected from one or more of iron chloride, cobalt chloride, nickel chloride, copper chloride, and manganese chloride.

According to one embodiment of the invention, the first temperature is between 20 ℃ and 60 ℃ and the second temperature is between 50 ℃ and 80 ℃.

According to one embodiment of the invention, the first time is between 0.5h and 24h and the second time is between 0.5h and 24 h.

According to one embodiment of the invention, the time of the acid treatment is between 0.5h and 8 h.

According to an embodiment of the present invention, the method further comprises adding a transition metal salt in step S1, and performing ultrasonic treatment for 1min to 60min to obtain a mixed solution.

According to an embodiment of the invention, the method further comprises stirring for 1-60 min after the ultrasonic treatment to obtain a mixed solution.

According to one embodiment of the present invention, the strong alkali solution is selected from one or more of sodium hydroxide solution and potassium hydroxide solution, and the concentration of the strong alkali solution is 0.01M to 10M.

According to one embodiment of the present invention, the strong acid solution is selected from one or more of a hydrochloric acid solution and a sulfuric acid solution, and the concentration of the strong acid solution is 0.01M to 10M.

According to one embodiment of the invention, the mass ratio of the graphene oxide to the transition metal salt is 1: 5-1: 20, the mass ratio of the transition metal salt to the strong base is 5: 1-1: 1, and the mass ratio of the strong base to the strong acid is 1: 1-5: 1.

According to the technical scheme, the invention has the beneficial effects that:

the invention provides a reversible regulation and control method of graphene oxide surface functional groups, which adopts a specific process to generate transition metal oxides or transition metal hydroxides as an inducer in different reaction processes, thereby realizing reversible regulation and control of the graphene surface functional groups. The method is simple and convenient to operate and low in cost, and the graphene can be designed into a conductive switch based on the method, so that the method has a good application prospect.

Detailed Description

The following presents various embodiments or examples in order to enable those skilled in the art to practice the invention with reference to the description herein. These are, of course, merely examples and are not intended to limit the invention. The endpoints of the ranges and any values disclosed in the present application are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to yield one or more new ranges of values, which ranges of values should be considered as specifically disclosed herein.

The invention provides a reversible regulation and control method of graphene oxide surface functional groups, which comprises the following steps: s1: providing a graphene oxide dispersion liquid, and adding a transition metal salt into the graphene oxide dispersion liquid to obtain a mixed liquid; s2: adding a strong alkali solution into the mixed solution, stirring the mixed solution at a first temperature for a first time, heating the mixed solution to a second temperature, and stirring the mixed solution for a second time to react to obtain graphene oxide with the functional groups removed; s3: placing the graphene oxide with the functional group removed in a strong acid solution for acid treatment to obtain graphene oxide with recovered functional group; wherein, reversible regulation of the graphene oxide surface functional group is realized by sequentially repeating the steps S1, S2 and S3.

According to the invention, the graphene has very excellent conductivity, and the graphene oxide containing functional groups is an insulator, so that the graphene can be designed into a conductive switch by reversibly regulating and controlling the surface functional groups of the graphene oxide, and the application of the conductive switch is further expanded. Existing methods can only permanently add or remove functional groups on graphene, but cannot achieve reversible transformations. The inventors of the present invention found that reversible regulation of graphene oxide surface functional groups can be effectively achieved by using a transition metal oxide or a transition metal hydroxide as an inducer.

The reversible control method of the graphene oxide surface functional group according to the present invention is specifically described below.

First, in step S1, a graphene oxide dispersion liquid is provided, and a transition metal salt is added to the graphene oxide dispersion liquid to obtain a mixed solution.

The graphene oxide dispersion may be obtained using a method conventional in the art. For example: graphene oxide is dispersed in water, and a dispersant such as polyvinyl alcohol, hydroxymethyl cellulose and the like can be added in a proper amount to obtain a uniformly dispersed graphene oxide dispersion liquid.

Further, adding a transition metal salt into the obtained graphene oxide dispersion liquid, and adding the transition metal salt into the graphene oxide dispersion liquid for mixing to enable metal ions to be adsorbed on the surface of the graphene oxide functional group.

In some embodiments, the transition metal salt may be one or more of a transition metal sulfate selected from one or more of iron sulfate, cobalt sulfate, nickel sulfate, copper sulfate, and manganese sulfate, a transition metal nitrate selected from one or more of iron nitrate, cobalt nitrate, nickel nitrate, copper nitrate, and manganese nitrate, and a transition metal chloride selected from one or more of iron chloride, cobalt chloride, nickel chloride, copper chloride, and manganese chloride.

Preferably, the ultrasonic treatment is performed for 1min to 60min after the transition metal salt is added, for example, 1min, 5min, 10min, 20min, 28min, 30min, 37min, 50min, etc., and more preferably, the ultrasonic treatment is performed after the stirring is performed for 1min to 60min, for example, 1min, 10min, 24min, 25min, 28min, 40min, 42min, 50min, etc., to obtain a more uniform mixed solution.

Next, in step S2, a strong alkali solution is added to the mixed solution obtained in step S1, and the mixture is stirred at a first temperature for a first time, and then heated to a second temperature and stirred for a second time to perform a reaction. When a strong alkaline solution is added, metal oxide or metal hydroxide is formed in situ, and the metal oxide/hydroxide interacts with functional groups on the surface of the graphene oxide to form a new metal-oxygen-carbon covalent bond. It should be noted here that the solubility of the base should not be too high, otherwise permanent removal of the functional groups may result.

In some embodiments, the alkali solution is sodium hydroxide solution, potassium hydroxide solution, etc., and the concentration of the alkali solution is 0.01M to 10M, for example, 0.01M, 0.05M, 0.1M, 0.5M, 1M, 4M, 7M, 8M, etc., preferably 0.1M to 1M.

In some embodiments, the first temperature is 20 ℃ to 60 ℃, e.g., 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, etc., and the second temperature is 50 ℃ to 80 ℃, e.g., 50 ℃, 60 ℃, 70 ℃, 80 ℃, etc. The first time is 0.5h to 24h, for example, 0.5h, 1h, 3h, 5h, 10h, 12h, 13h, 15h, 20h, etc., and the second time is 0.5h to 24h, for example, 0.5h, 1h, 2h, 3h, 7h, 12h, 15h, 18h, 21h, etc. After the reaction is finished, centrifugally separating the reaction product, and washing the reaction product to be neutral by using deionized water to obtain the graphene oxide with the functional groups removed. For the present invention, the temperature cannot be raised directly to the second temperature during the temperature raising process because the gibbs free energy is smaller at low temperatures, which is beneficial for nucleation.

Further, in step S3, the graphene oxide with the functional group removed, obtained in step S2, is placed in a strong acid solution to be subjected to an acid treatment. At this time, by adding a strong acid, the metal-oxygen-carbon covalent bond may be broken, thereby restoring the functional group of graphene oxide.

In some embodiments, the strong acid solution is selected from a hydrochloric acid solution, a sulfuric acid solution, and the like, and the concentration of the strong acid solution is 0.01M to 10M, for example, 0.01M, 0.08M, 1M, 1.5M, 3M, 5M, 9M, and the like, preferably 0.1M to 1M. The acid treatment time is 0.5 to 8 hours, for example, 0.5 hour, 1 hour, 1.5 hours, 4 hours, 5 hours, 6 hours, 7.5 hours, and the like. After acid treatment, washing the graphene oxide film to be neutral by deionized water, and then restoring the graphene oxide functional group. By repeating the above steps S1, S2, and S3, reversible regulation of graphene oxide surface functional groups can be achieved.

According to the present invention, the mass ratio of the graphene oxide to the transition metal salt is 1:5 to 1:20, for example, 1:5, 1:10, 1:15, 1:18, 1:20, etc., the mass ratio of the transition metal salt to the strong base is 5:1 to 1:1, for example, 5:1, 4:1, 3:1, 2:1, 1:1, etc., and the mass ratio of the strong base to the strong acid is 1:1 to 5:1, for example, 1:1, 2:1, 3:1, etc.

In conclusion, the invention adopts a specific regulation method, and generates transition metal oxide or transition metal hydroxide as an inducer in different reaction processes, thereby realizing reversible regulation of the graphene surface functional groups.

The invention will be further illustrated by the following examples, but is not to be construed as being limited thereto. Unless otherwise specified, reagents, materials and the like used in the present invention are commercially available.