CN106783237A - A kind of Co Fe alloy/graphites alkene composite and its preparation method and application - Google Patents

Abstract

The invention belongs to the technical field of electrochemistry, and discloses a Co-Fe alloy/graphene composite material and a preparation method and application thereof. Ultrasonic disperse graphene oxide in water; stir and dissolve 1,1'-ferrocenecarboxylic acid and cobalt acetate tetrahydrate in graphene oxide dispersion at room temperature; Add alkali while stirring, adjust the pH of the solution to 4~12, and then stir for 2~10 h; transfer the obtained system to a hydrothermal kettle, heat at 40~200°C for 48~72 h, cool to room temperature, and take out the reaction liquid, separated to obtain the precipitate, and dried it; ground, and calcined the ground powder at 400-600°C for 2-8 hours in a nitrogen atmosphere to obtain a Co-Fe alloy/graphene composite material. The present invention prepares the Co-Fe alloy/graphene composite material and uses it as the electrode material of the supercapacitor, the electrochemical performance of the capacitor is greatly improved, and has very broad development prospects.

Description

A kind of Co-Fe alloy/graphene composite material and its preparation method and application

technical field

The invention belongs to the technical field of electrochemistry, and in particular relates to a Co-Fe alloy/graphene composite material and a preparation method and application thereof.

Background technique

Graphene is a two-dimensional sheet material with high specific surface area and excellent electrical conductivity. It has a wide range of applications in the field of electrochemistry. The combination of Co-Fe alloy and graphene greatly improves its electrochemical performance. At present, the methods for composite metal alloys based on graphene mainly include: mechanical mixing method, in-situ growth method, etc. For the first two methods, the mechanical mixing method is simple to implement, but it is not easy to obtain a composite material with a uniform composite state; while the in-situ growth method has high requirements on operating conditions, and the prepared nanoparticles are also easy to agglomerate.

Supercapacitors (or electrochemical capacitors) have become a new star in the field of energy storage devices, and have received great attention from researchers in recent years. At present, according to the interfacial chemistry and physical energy storage mechanism, electrochemical capacitors can be divided into two categories: one is the electric double layer capacitor (EDLC), the electrode material is made of carbon materials with high surface area; the other is the pseudocapacitor. (pseudocapacitor), whose energy storage mechanism is based on oxidation-reduction reactions to achieve energy storage, such as conductive polymers and transition metal oxides. Graphene-based electrochemical capacitors mainly improve the capacitance performance from two aspects, namely, the development of new materials and the exploration of potential basic energy storage mechanisms.

Contents of the invention

In order to improve the capacitive performance of supercapacitors, the present invention starts from the development of new materials, and aims to provide a Co-Fe alloy/graphene composite material and its preparation method, and apply it in supercapacitors.

In order to achieve the above object, the technical scheme that the present invention takes is as follows:

A preparation method of Co-Fe alloy/graphene composite material, the steps are as follows:

(1) Ultrasonic dispersion of graphene oxide in water;

(2) Stirring and dissolving 1,1'-ferrocenecarboxylic acid and cobalt acetate tetrahydrate in the graphene oxide dispersion obtained in step (1) at room temperature;

(3) Control the temperature at 20-80°C, add alkali to the solution obtained in step (2) while stirring, adjust the pH of the solution to 4-12, and then stir for 2-10 h;

(4) Transfer the system obtained in step (3) to a hydrothermal kettle, heat it in water at 40-200°C for 48-72 hours, cool to room temperature, take out the reaction solution, separate and obtain the precipitate, and dry it;

(5) The precipitate obtained in the grinding step (4) is dried, and the ground powder is calcined at 400-600°C for 2-8 hours in a nitrogen atmosphere to obtain a Co-Fe alloy/graphene composite material;

Among them, in terms of mass volume ratio, graphene oxide: water: 1,1'-ferrocenecarboxylic acid: cobalt acetate tetrahydrate = 0.2~0.7g: 300~400mL: 1g: 1~9g.

Preferably, the alkali is sodium hydroxide, which is added in the form of an aqueous solution, and the concentration of the aqueous sodium hydroxide solution is 0.1-0.5 mol/L.

Preferably, the separation is centrifugal separation, and the centrifugal speed is 6000~8000r/min.

The Co-Fe alloy/graphene composite material prepared by the preparation method.

Application of the Co-Fe alloy/graphene composite material in supercapacitors.

Further, Co-Fe alloy/graphene composites are used as electrode materials.

Beneficial effect:

The present invention prepares the Co-Fe alloy/graphene composite material and uses it as the electrode material of the supercapacitor, the electrochemical performance of the capacitor is greatly improved, and has broad development prospects.

Description of drawings

Figure 1: Infrared images of Co-Fe alloy/graphene composites.

Figure 2: Thermogravimetric analysis of the Co-Fe alloy/graphene composite.

Figure 3: Cyclic voltammogram of Co-Fe alloy/graphene composite.

detailed description

The present invention will be described in further detail below in conjunction with specific examples, but the protection scope of the present invention is not limited thereto.

Example 1

(1) Graphene oxide was prepared by the improved Hummers method, 300mg graphene oxide was mixed with 400mL deionized water, and the mixture obtained by the two was ultrasonically dispersed for 6 h, and the solution was irradiated with a flashlight beam, and no Obvious particle aggregates indicate that graphene oxide is well dispersed in aqueous solution, thereby obtaining a uniformly dispersed yellow-brown graphene oxide dispersion;

(2) Dissolve 1g of yellow-brown 1,1'-ferrocenecarboxylic acid powder and 1g of pink cobalt acetate tetrahydrate powder in the graphene oxide dispersion obtained in step (1) at room temperature, stir, Until all the solids are dissolved, the solution turns from yellowish brown to black red;

(3) Put the yellow-brown solution obtained in step (2) into a constant temperature magnetic stirring water bath, control the constant temperature of the water bath at 70°C, turn on the magnetic stirring, and add sodium hydroxide solution (0.1M) dropwise during the stirring process to adjust the pH of the solution to 6, and then stirred for 8h;

(4) Transfer the system obtained in step (3) to a hydrothermal kettle, control the temperature at 45°C, and heat it in water for 50 hours. After the reaction, take out the reaction solution from the hydrothermal kettle, wash and centrifuge it with water several times (control the speed at 6000r/ min), and the centrifuged precipitate was dried in an oven at 60°C to obtain a Co-Fe alloy/graphene composite material precursor;

(5) Put the Co-Fe alloy/graphene composite material precursor obtained in step (4) in an agate mortar, grind it carefully for 0.5h, transfer the ground powder to a porcelain boat, and place it in a tube furnace Under a nitrogen atmosphere, the temperature was raised to 500°C for 6 hours at a heating rate of 10°C/min to obtain a Co-Fe alloy/graphene composite material.

The infrared image of the prepared Co-Fe alloy/graphene composite is shown in Figure 1. Because the calcination is not clean, part of graphene oxide will remain, and graphene oxide contains a large amount of oxygen-containing functional groups, so in the final Co-Fe alloy/graphene composite material, it will also be damaged due to the remaining part of graphene oxide. Contains a large number of oxygen-containing functional groups, as shown in Figure 1: the broad and strong absorption peak between 3700 and 3500 cm ^-1 corresponds to the stretching vibration of the hydroxyl group, the absorption peak at 1723 cm ^-1 corresponds to the stretching vibration of the carbonyl group, and the absorption peak between 950 and 3500 cm The absorption peak at 900 cm ^-1 corresponds to the stretching vibration of the epoxy group, 780 cm ^-1 is the characteristic absorption peak of Fe-O, and at 564 cm ^-1 and 667 cm ^-1 is the characteristic absorption peak of Co-O, indicating the formation of Stable Co-Fe alloy/graphene composites.

The prepared Co-Fe alloy/graphene composite material was placed in air, and was calcined from room temperature to 1000 °C at a heating rate of 10 °C/min to obtain a thermogravimetric curve, as shown in Figure 2. In the curve, the mass decreases by 37% at 300-410°C, which is caused by the decomposition of graphene in the composite material. After the temperature is greater than 800°C, the curve becomes flat, indicating that the graphene has been completely decomposed.

Electrochemical performance test:

The electrochemical test process is carried out on an electrochemical workstation (CHI760E) through a three-electrode system consisting of a working electrode, a reference electrode and a counter electrode. The electrolyte is 6mol/L Na ₂ SO ₄ solution or KOH solution, and the scan rate is is 50mv/s, Co-Fe alloy/graphene composite material is the active material of the working electrode, the saturated calomel electrode (SCE) is the reference electrode, and the platinum electrode is the counter electrode. The working electrode was prepared according to the following process:

(1) Pulping: Accurately weigh the Co-Fe alloy/graphene composite material, binder (12 wt % PTFE emulsion) and conductive agent (Super P) at a mass ratio of 8:1:1, and add an appropriate amount of of absolute ethanol, and a uniformly dispersed slurry was obtained after ultrasonication for 30 min;

(2) Coating: evenly coat the prepared slurry on a pre-cut and weighed foamed nickel disc (r=7 mm);

(3) Sheet making: Put the coated nickel foam into an oven at 60°C to fully dry it, and press it with a double-roller machine to obtain an electrode sheet (working electrode).

The obtained cyclic voltammogram is shown in Figure 3. It can be seen from Figure 3 that when Na ₂ SO ₄ solution or KOH solution is used as the electrolyte, the cyclic voltammogram obtained in the cyclic voltammetry measurement all presents a relatively regular rectangle, showing the electric double layer capacitance characteristics of the material.

Example 2

(1) Prepare graphene oxide by the improved Hummers method, mix 0.2mg graphene oxide with 300mL deionized water, and ultrasonically disperse the resulting mixture for 4 h. Obvious particle aggregates are found, indicating that graphene oxide is well dispersed in aqueous solution, thereby obtaining a uniformly dispersed yellow-brown graphene oxide dispersion;

(2) Dissolve 1g of yellow-brown 1,1'-ferrocenecarboxylic acid powder and 5g of pink cobalt acetate tetrahydrate powder in the graphene oxide dispersion obtained in step (1) at room temperature, stir, Until all the solids are dissolved, the solution turns from yellowish brown to black red;

(3) Put the yellow-brown solution obtained in step (2) into a constant temperature magnetic stirring water bath, control the constant temperature of the water bath at 30°C, turn on the magnetic stirring, and add sodium hydroxide solution (0.3M) dropwise during the stirring process to adjust the pH of the solution to 4, and then stirred for 2h;

(4) Transfer the system obtained in step (3) to a hydrothermal kettle, control the temperature at 100°C, and heat it for 48 hours. After the reaction, take out the reaction solution from the hydrothermal kettle, wash and centrifuge it with water several times (control the speed at 7000r/ min), and the centrifuged precipitate was dried in an oven at 40°C to obtain a Co-Fe alloy/graphene composite material precursor;

(5) Put the Co-Fe alloy/graphene composite material precursor obtained in step (4) in an agate mortar, grind it carefully for 0.5h, transfer the ground powder to a porcelain boat, and place it in a tube furnace Under a nitrogen atmosphere, the temperature was raised to 400°C for 4 hours at a heating rate of 10°C/min to obtain a Co-Fe alloy/graphene composite material.

Example 3

(1) Prepare graphene oxide by the improved Hummers method, mix 0.7mg graphene oxide with 400mL deionized water, and ultrasonically disperse the resulting mixture for 8 h. Obvious particle aggregates are found, indicating that graphene oxide is well dispersed in aqueous solution, thereby obtaining a uniformly dispersed yellow-brown graphene oxide dispersion;

(2) Dissolve 1g of yellow-brown 1,1'-ferrocenecarboxylic acid powder and 9g of pink cobalt acetate tetrahydrate powder in the graphene oxide dispersion obtained in step (1) at room temperature, stir, Until all the solids are dissolved, the solution turns from yellowish brown to black red;

(3) Put the yellow-brown solution obtained in step (2) into a constant temperature magnetic stirring water bath, control the constant temperature of the water bath at 50°C, turn on the magnetic stirring, and add sodium hydroxide solution (0.5M) dropwise during the stirring process to adjust the pH of the solution to 12, and then stirred for 10h;

(4) Transfer the system obtained in step (3) to a hydrothermal kettle, control the temperature at 200°C, and heat the water for 72 hours. After the reaction, take out the reaction solution from the hydrothermal kettle, wash and centrifuge it several times (control the speed at 8000r/ min), and the centrifuged precipitate was dried in an oven at 50°C to obtain a Co-Fe alloy/graphene composite material precursor;

(5) Put the Co-Fe alloy/graphene composite material precursor obtained in step (4) in an agate mortar, grind it carefully for 1 hour, transfer the ground powder to a porcelain boat, and place it in a tube furnace. Under a nitrogen atmosphere, the temperature was raised to 600°C at a rate of 10°C/min and calcined for 8 hours to obtain a Co-Fe alloy/graphene composite material.

Claims (6)

1. a kind of preparation method of Co-Fe alloy/graphites alkene composite, it is characterised in that step is as follows：

（1）, by graphene oxide ultrasonic disperse in water；

（2）, at ambient temperature, by 1,1 '-ferrocenecarboxylic acid and four hydration cobalt acetate stirring and dissolvings in step（1）The oxygen of gained In graphite alkene dispersion liquid；

（3）, temperature control at 20 ~ 80 DEG C, to step（2）Add alkali in resulting solution while stirring, the pH for adjusting solution is 4 ~ 12, then is stirred Mix 2 ~ 10 h；

（4）, by step（3）Gained system is transferred in water heating kettle, 40 ~ 200 DEG C of 48 ~ 72h of hydro-thermal, after being cooled to room temperature, is taken out Reaction solution, isolated sediment, is baked to；

（5）, grinding steps（4）Gained sediment after drying, forges by ground powder in a nitrogen atmosphere at 400 ~ 600 DEG C 2 ~ 8h is burnt, Co-Fe alloy/graphite alkene composites are obtained final product；

Wherein, based on mass volume ratio, graphene oxide: water: 1,1 '-ferrocenecarboxylic acid: four hydration cobalt acetate=0.2 ~ 0.7g: 300~400mL∶1g∶1~9g。

2. preparation method as claimed in claim 1, it is characterised in that：The alkali is NaOH, is added in its aqueous solution form Enter, the concentration of sodium hydrate aqueous solution is 0.1 ~ 0.5 mol/L.

3. preparation method as claimed in claim 1, it is characterised in that：It is described to be separated into centrifugation, centrifugal rotational speed is 6000 ~ 8000r/min。

4. the Co-Fe alloy/graphite alkene composites that prepared by the preparation method as described in any one of claim 1 ~ 3.

5. application of the Co-Fe alloy/graphites alkene composite as claimed in claim 4 in ultracapacitor.

6. application as claimed in claim 5, it is characterised in that：Co-Fe alloy/graphite alkene composites are used as electrode material.