阅读说明：本技术 一种在石墨烯表面电沉积制备层状双金属氢氧化物的方法 (Method for preparing layered double hydroxide on graphene surface through electrodeposition ) 是由 胡吉明 徐腾 于 2021-09-06 设计创作，主要内容包括：本发明公开了一种在石墨烯表面电沉积制备层状双金属氢氧化物的方法。制备步骤是将石墨烯直接分散到沉积前驱液中,采用三电极体系,在快速搅拌下进行电沉积制备,以铂片作为工作电极,铂网作为辅助电极,在工作电极上施加阴极电位,通过沉积液中石墨烯纳米片与铂电极的电化学碰撞实现电子转移,从而在石墨烯表面原位“碱催化”沉积制备得到层状双金属氢氧化物。采用该方法制备的层状双金属氢氧化物与石墨烯基体具有良好的结合力,解决了传统技术难以在缺乏活性基团的普通石墨烯表面直接沉积层状双金属氢氧化物的不足。层状双金属氢氧化物修饰的石墨烯有望在金属的腐蚀与防护、电催化材料、高性能超级电容器、工业分析分离等领域取得应用。(The invention discloses a method for preparing layered double hydroxides on the surface of graphene by electrodeposition. The preparation method comprises the steps of directly dispersing graphene into deposition precursor liquid, adopting a three-electrode system, carrying out electrodeposition preparation under rapid stirring, taking a platinum sheet as a working electrode and a platinum net as an auxiliary electrode, applying cathode potential on the working electrode, and realizing electron transfer through electrochemical collision of the graphene nanosheet and the platinum electrode in the deposition liquid, so that the layered double hydroxide is prepared on the surface of the graphene through in-situ alkali catalysis deposition. The layered double hydroxide prepared by the method has good binding force with a graphene substrate, and the defect that the layered double hydroxide is difficult to directly deposit on the surface of common graphene lacking active groups in the traditional technology is overcome. The graphene modified by the layered double hydroxide is expected to be applied to the fields of corrosion and protection of metals, electrocatalytic materials, high-performance supercapacitors, industrial analysis and separation and the like.)

1. A method for preparing layered double hydroxides on the surface of graphene through electrodeposition is characterized by comprising the following steps:

1) preparing an electrodeposition precursor solution: mixing and stirring 50-100 mL of anhydrous ethanol and 50-100 mL of deionized water, sequentially adding 0.25-2 g of metal sulfate and 1-3 g of supporting electrolyte, and uniformly stirring for later use;

2) adding the prepared electro-deposition precursor solution into a three-electrode electrolytic tank, adding 10-140 mg of graphene, and performing ultrasonic dispersion uniformly, wherein Ag/AgCl is used as a reference electrode, a platinum sheet is used as a working electrode, and a platinum net is used as a counter electrode;

3) carrying out electrodeposition under the condition of keeping the stirring speed at 500-1000 rmp, wherein the deposition temperature is 30 ℃, the potential of the electrodeposition is controlled at-0.5 to-3.0V, and the deposition time is 10-100 min;

4) washing the deposition product with deionized water and ethanol for 3-5 times, and centrifugally drying, wherein the centrifugal separation speed of the deposition product is 5000-10000 rpm, the centrifugal time is 5-15 min, and the drying temperature of the deposition product is 50-80 ℃.

2. The method of claim 1, wherein said layered double hydroxide comprises Co-Fe, Ni-Fe, Zn-Fe, Mg-Fe, Co-Al, Ni-Al, Zn-Al, Mg-Al, Ni-Cu, Co-Mn double hydroxides.

3. The method of claim 1, wherein the metal sulfate is CoSO₄·7H₂O、Fe(NH₂)₂(SO₄)₂·6H₂O、Al₂(SO₄)₃、NiSO₄·7H₂O、ZnSO₄·7H₂O、MgSO₄·7H₂O、CuSO₄·5H₂O、MnSO₄·4H₂Two kinds of O.

4. The method according to claim 1, wherein the addition amount of the graphene is preferably controlled to be 20-100 mg.

5. The method of claim 1, wherein the supporting electrolyte is potassium nitrate or sodium sulfate.

6. The method according to claim 1, wherein the electrodeposition potential is preferably controlled to be-0.8 to-1.6V.

7. The method according to claim 1, wherein the electrodeposition time is preferably 20 to 80 min.

Technical Field

The invention relates to surface modification of graphene, in particular to a method for preparing Layered Double Hydroxides (LDHs) by direct electrodeposition on the surface of graphene with good bonding force.

Background

Graphene, as a novel two-dimensional carbon nanomaterial, has a large theoretical specific surface area, excellent conductivity and mechanical properties, good chemical stability and shielding properties, and is widely applied to multiple fields of nano drug loading, supercapacitors, electrochemical sensors, solar cells, metal corrosion and protection and the like. However, the common graphene has higher chemical inertness and is not easy to be uniformly dispersed due to the lack of active groups on the surface, and the application limit of the common graphene can be broken only by adopting a method of introducing active functional groups through surface chemical modification. At present, graphene oxide is mainly used as a raw material for modifying the surface of graphene, and modification is realized through abundant active functional groups. And the direct modification of the inert surface of the common graphene by means of compound deposition and the like is very little.

LDHs is an inorganic clay material, which is composed of a main layer plate consisting of two or more metal cations and interlayer anions. The LDHs has the characteristics of variable chemical composition of a host laminate, variable types and quantity of interlayer guest ions, high specific capacity, rich electroactive sites, simple and convenient synthesis and low cost, and is widely applied to the fields of metal corrosion and protection, drug delivery, energy storage, supercapacitors, photocatalysis and the like. However, the LDHs have low mechanical strength and poor conductivity, and are not suitable for application. Therefore, the LDHs and the graphene with excellent mechanical property and conductivity form a compound, and the method is beneficial to improving the performance of the LDHs and expanding the application range of the graphene. However, most of the existing composite materials of LDHs and graphene are formed by compounding LDH and graphene oxide with a large number of active functional groups, and the direct preparation of the layered double hydroxide-graphene composite material on the common graphene is not reported.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a method for preparing layered double hydroxides on the surface of graphene by direct electrodeposition, namely a preparation method for directly growing the layered double hydroxides with good bonding force and controllable morphology on the surface of the graphene.

The purpose of the invention is realized by the following technical scheme:

a method for preparing layered double hydroxides on the surface of graphene through electrodeposition comprises the following steps:

1) preparing an electrodeposition precursor solution: mixing and stirring 50-100 mL of anhydrous ethanol and 50-100 mL of deionized water, sequentially adding 0.25-2 g of metal sulfate and 1-3 g of supporting electrolyte, and uniformly stirring for later use;

2) adding the prepared deposition precursor solution into a three-electrode electrolytic tank, adding 10-140 mg of graphene, and performing ultrasonic dispersion uniformly, wherein Ag/AgCl is used as a reference electrode, a platinum sheet is used as a working electrode, and a platinum net is used as a counter electrode;

3) carrying out electrodeposition under the condition of keeping the stirring speed at 500-1000 rmp, wherein the deposition temperature is 30 ℃, the potential of the electrodeposition is controlled at-0.5 to-3.0V, and the deposition time is 10-100 min;

4) washing the deposition product with deionized water and ethanol for 3-5 times, and centrifugally drying, wherein the centrifugal separation speed of the deposition product is 5000-10000 rpm, the centrifugal time is 5-15 min, and the drying temperature of the deposition product is 50-80 ℃.

The layered double metal hydroxide is Co-Fe, Ni-Fe, Zn-Fe, Mg-Fe, Co-Al, Ni-Al, Zn-Al, Mg-Al, Ni-Cu, Co-Mn double metal hydroxide.

The metal sulfate used is CoSO₄·7H₂O、Fe(NH₂)₂(SO₄)₂·6H₂O、Al₂(SO₄)₃、NiSO₄·7H₂O、ZnSO₄·7H₂O、MgSO₄·7H₂O、CuSO₄·5H₂O、MnSO₄·4H₂Two kinds of O.

The addition amount of the graphene is preferably controlled to be 20-100 mg.

The supporting electrolyte is potassium nitrate or sodium sulfate.

The electrodeposition potential is preferably controlled to be-0.8 to-1.6V.

The deposition time of the electrodeposition is preferably 20-80 min.

The invention has the beneficial effects that:

the invention provides the method for directly depositing layered double hydroxides on common graphene powder in batch, compared with the conventional hydrothermal method, the layered double hydroxides prepared by the method have good binding force with common graphene, and the defect that the layered double hydroxides can only be deposited on the surface of oxidized graphene and are difficult to be directly deposited on the surface of the common graphene in the conventional technology is overcome. The method is simple, controllable, environment-friendly, safe and low in cost, and is expected to realize large-scale industrial application.

Drawings

FIG. 1a is a SEM photograph of graphene before electrodeposition of double metal hydroxide;

FIG. 1b is an SEM photograph of graphene after electrodeposition of a double metal hydroxide;

fig. 2 is an XRD pattern of the electrodeposited layered double hydroxide-supported graphene.

Detailed Description

The invention discloses a method for preparing Layered Double Hydroxide (LDH) on the surface of graphene by direct electrodeposition. The preparation method comprises the steps of directly dispersing graphene into deposition precursor liquid, adopting a three-electrode system, carrying out electrodeposition preparation under rapid stirring, taking a platinum sheet as a working electrode and a platinum net as an auxiliary electrode, applying cathode potential on the working electrode, and realizing electron transfer through electrochemical collision of the graphene nanosheet and the platinum electrode in the deposition liquid, so that the layered double hydroxide is prepared on the surface of the graphene through in-situ alkali catalysis deposition. The layered double hydroxide prepared by the method has good binding force with graphene, and the defect that the layered double hydroxide is difficult to directly deposit on the surface of common graphene lacking active groups in the traditional technology is overcome. The graphene modified by the layered double hydroxide is expected to be applied to the fields of corrosion and protection of metals, electrocatalytic materials, high-performance supercapacitors, industrial analysis and separation and the like.

The invention is further illustrated below with reference to the figures and examples.

Example 1

Electrodeposition of cobalt-iron double hydroxides on graphene powder

1) Preparing a precursor solution: 50 mL of deionized water and 50 mL of ethanol were added to a 100 mL beaker, and 0.5 g of CoSO was added₄·7H₂O、1.0 g Fe(NH₂)₂(SO₄)₂·6H₂O and 1.5 g NaNO₃Stirring uniformly for later use;

2) adding 0.04 g of graphene into the precursor solution, uniformly dispersing by ultrasonic for 40 min, wherein the ultrasonic power is 180W, a platinum sheet is taken as a working electrode, Ag/AgCl is taken as a reference electrode, a platinum net is taken as a counter electrode, the electrodeposition potential is-1.2V, the deposition time is 40 min, and the deposition temperature is 30 ℃;

3) after deposition, the substrate is washed twice by deionized water and ethanol respectively, the centrifugal speed is 7000 rpm, the time is 15 min, and finally the substrate is dried in an oven at 60 ℃.

When the obtained sample is subjected to Scanning Electron Microscope (SEM) observation and X-ray diffraction (XRD), as is apparent from fig. 1a and 1b, the graphene sheet layer after the electrodeposition of the bimetal hydroxide in fig. 1b is rougher than the original graphene surface, and the typical scale-like lamellar structure of the ferrocobalt bimetal hydroxide exhibits an orientation perpendicular to the graphene nanosheet, indicating that the bimetal hydroxide is successfully deposited on the sheet-layer graphene by the method. The XRD pattern of figure 2 shows the relevant diffraction peaks of the cobalt-iron layered double hydroxide, which indicates that the cobalt-iron double hydroxide-graphene composite is prepared by the surface electrodeposition of graphene.

Example 2

The procedure was carried out in a similar manner to example 1 except that the amount of the metal sulfate added was changed, and after drying the obtained sample powder in an oven at 80 ℃ for 2 days, the sample was weighed and the test results were as shown in Table 1.

TABLE 1 influence of different metal sulfate amounts

Example 3

The specific implementation steps are similar to those of example 1, only the addition amount of graphene is changed, the sample powder is dried in an oven at 80 ℃ for 2 days, and then the sample mass is weighed, and the test results are shown in table 2.

TABLE 2 influence of graphene addition

Example 4

The procedure was carried out analogously to example 1, except that the deposition potential was varied, and after drying the sample powder in an oven at 80 ℃ for 2 days, the sample mass was weighed and the test results are given in Table 3.

TABLE 3 Effect of deposition potential

Example 5

The procedure was carried out analogously to example 1, with the deposition time only being changed, and the sample masses were weighed after drying the sample powders in an oven at 80 ℃ for 2 days, the test results being shown in Table 4.

TABLE 4 influence of deposition time

Example 6

Electrodeposition of nickel-iron bimetallic hydroxide on graphene powder

1) Preparing a precursor solution: 50 mL of deionized water and 50 mL of ethanol were added to a 100 mL beaker, and 0.8 g of NiSO was added₄·7H₂O、1.0 g Fe(NH₂)₂(SO₄)₂·6H₂O and 2.0 g NaNO₃Stirring uniformly for later use;

2) adding 0.06 g of graphene into the precursor solution, uniformly dispersing by ultrasonic for 40 min, wherein the ultrasonic power is 180W, a platinum sheet is taken as a working electrode, Ag/AgCl is taken as a reference electrode, a platinum net is taken as a counter electrode, the electrodeposition potential is-1.6V, the deposition time is 50 min, and the deposition temperature is 30 ℃;

3) and (3) after deposition, washing with deionized water and ethanol twice respectively, centrifuging at 7000 rpm for 15 min, and finally drying in a 60 ℃ oven to obtain the ferronickel double metal hydroxide.

Example 7

Electrodeposition of cobalt-aluminum double metal hydroxides on graphene powder

1) Preparing a precursor solution: 50 mL of deionized water and 50 mL of ethanol were added to a 100 mL beaker, and 1.0 g of CoSO was added₄·7H₂O、2.0 g Al₂(SO₄)₃And 1.5 g NaNO₃Stirring uniformly for later use;

2) adding 0.08 g of graphene into the precursor solution, uniformly dispersing by ultrasonic for 40 min, wherein the ultrasonic power is 180W, a platinum sheet is taken as a working electrode, Ag/AgCl is taken as a reference electrode, a platinum net is taken as a counter electrode, the electrodeposition potential is-0.8V, the deposition time is 80 min, and the deposition temperature is 30 ℃;

3) and (3) after deposition, washing the substrate twice by using deionized water and ethanol respectively, centrifuging at the rotating speed of 7000 rpm for 15 min, and finally drying the substrate in an oven at the temperature of 60 ℃ to obtain the cobalt-aluminum double hydroxide.

The above-described embodiments are intended to be illustrative, rather than restrictive, of the present invention, and any modifications and variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims.