CN105314688B - A kind of preparation method and applications of nickel oxide nano piece - Google Patents

Abstract

The invention provides a preparation method and application of nickel oxide nanosheets. The preparation method includes the following steps: a. adding soluble nickel salt and sodium citrate into water in proportion and mixing them thoroughly to obtain a homogeneous solution; b. Potassium tetracyanonickel (II) is added to water and mixed fully to obtain a homogeneous solution, c, the solution obtained in step a is added to the solution in step b, and then left to stand to obtain growth with a light green precipitate, d, Then the light green precipitate obtained in step c was collected by centrifugation, fully washed with deionized water and ethanol, the obtained product was heat-preserved and dried, then heat-treated at different temperatures, and calcined to obtain light green nickel oxide nanosheet powder. The nickel oxide nanosheets can be used for supercapacitor electrodes. The beneficial effect of the present invention is that the nickel oxide nanosheet has a larger specific surface area, and has the advantages of good specific capacity and cycle performance when used to construct supercapacitor electrodes.

Description

A kind of preparation method and application of nickel oxide nanosheet

technical field

The invention belongs to the technical field of inorganic advanced materials and the technical field of electrochemical energy storage, and in particular relates to a preparation method and application of nickel oxide nanosheets.

Background technique

Due to the characteristics of large capacitance, power density, energy density and long life, the research on supercapacitors has attracted much attention in recent years (Nanoscale, 2013, 5(10): 4378-4387), and it is expected to become a new type of green capacitor in the 21st century. energy. It is well known that the renewal of electrode materials plays a decisive role in the performance of supercapacitors. Conventional high specific surface activated carbon materials are used as electrodes to increase the electric double layer capacitance of capacitors. However, for more than ten years in the middle, the development of supercapacitors was once stagnant due to the use of carbon materials as electrode materials. At the end of the last century, with the rapid development of nanotechnology, people have gradually deepened their understanding of the importance of the pore size of carbon materials with high surface area. The development and utilization of oxides has greatly promoted the development of supercapacitors. The electricity storage mechanism of most metal oxides as electrodes belongs to the redox interface electricity storage. In view of the small specific capacitance of carbon-based materials and the high price of ruthenium-based materials in the current supercapacitor research, people try to synthesize alternative oxide electrode materials with low price and good performance (such as nickel oxide, cobalt oxide, manganese oxide, etc. ). Among these alternative materials, nickel oxide has recently attracted extensive research and attention in the field of supercapacitors because of its excellent electrochemical performance and relatively low price. The literature shows that the energy storage of redox capacitors is mainly through redox reactions on or near the surface of electrode materials (such as metal oxides) (Electrochim. Acta, 2005, 50, 5641–5646). According to this energy storage mechanism, the preparation of nanomaterials is one of the effective methods to increase the Faraday quasi-capacitance of metal oxides. By changing the morphology of metal oxide nanomaterials, increasing the specific surface area of the material, improving the pore structure of the material, etc., the prepared metal oxide nanomaterials show excellent electrochemical performance.

At present, the main methods used to prepare nickel oxide nanosheets are: template method, radiation synthesis method, microemulsion method, chemical gas phase reaction method and hydrothermal method, etc. It is worth noting that the solution method and the hydrothermal method are good methods for preparing nickel oxide nanosheets, but most of the preparation processes need to adjust the pH value, and the yield is low, so it is difficult to promote on a large scale (J.Mater.Chem., 2011, 21, 18792-18798; "Journal of Anhui University (Natural Science Edition), Issue 03, 2013). The template method using nickel salt as raw material is not suitable for industrial production because of its expensive raw material price and many steps (J.Mater.Chem., 2011, 21, 6602-6606). In addition, the chemical vapor phase reaction method and the radiation synthesis method increase the production cost because of the special equipment required for their preparation. At present, from the perspective of simplifying operations and saving energy, the thermal decomposition of metal-organic compounds has gradually become the main research method for synthesizing nano-oxides (J.Phys.Chem.C, 2012, 116, 7227-7235). The product has the characteristics of uniform structure, no agglomeration, relatively large area, and rich channels, which has attracted widespread attention from many workers. So far, there have been no reports on the preparation of nickel oxide materials with two-dimensional, porous, nanosheet structures and their related applications by the thermal decomposition of metal-organic compounds. Therefore, it is of great significance to develop a simple, efficient, low-cost, and environmentally friendly preparation method to obtain nickel oxide nanosheet materials with uniform structure, rich pores, high surface area, and strong controllability.

Contents of the invention

The purpose of the present invention is to provide a preparation method and application of nickel oxide nanosheets with low preparation cost, easy to realize industrialization, effective and feasible implementation, and intact mesoscopic structure.

Technical scheme of the present invention is: the preparation method of nickel oxide nanosheet of the present invention, comprises the following steps:

a. Add soluble nickel salt and sodium citrate in proportion to water and mix thoroughly to obtain a homogeneous solution.

b. Add soluble potassium tetracyanonickelate (II) into water and mix thoroughly to obtain a homogeneous solution.

c. Add the solution obtained in step a to the solution in step b, and then let it stand to obtain a light green precipitate;

d. Then centrifuge the light green precipitate obtained in step c, wash it fully with deionized water and ethanol, place the product in a vacuum drying oven for heat preservation and drying, then heat treat it at different temperatures, and roast it to obtain light green oxide Nickel nanosheet powder.

Further, the molar ratio of the soluble nickel salt and sodium citrate in the step a is 1:2, and the amount of water in the step a is 200 mL.

Further, the amount of water in the step b is 200mL.

Further, the soluble nickel salt in step a is nickel chloride, nickel acetate, nickel nitrate or nickel sulfate.

Further, the standing time in the step c is The standing temperature in the step c is

Further, in the vacuum drying oven in the step d, the heat preservation and drying treatment is carried out at The temperature environment is carried out, and the duration is 12 hours.

Further, the heat treatment in the step d is preferably at In the temperature environment, the rate of heating is and the time is preferably

The nickel oxide nanosheets are used in the field of electrochemical energy storage, especially as supercapacitor electrode materials.

The nickel oxide nanosheets are composed of countless nanoparticle monomers, the nanoparticles are nickel oxide, the nanosheets are two-dimensional porous hexagons or pentagons, and the size of the nanosheet units is about The thickness is about 27nm.

The advantages and positive effects of the present invention are: the method of the present invention has simple preparation process, convenient operation, no environmental pollution, low energy consumption, good repeatability, and is suitable for large-scale industrial production; the nickel oxide obtained by the method of the present invention Nanosheets have a large specific surface area, and have the advantages of good specific capacity and cycle performance when used to construct supercapacitor electrodes.

Description of drawings

Fig. 1 is the X-ray diffraction spectrogram of sample in embodiment 1 and 2;

Fig. 2 is the low magnification scanning electron micrograph of sample in embodiment 1;

Fig. 3 is the high magnification transmission electron microscope figure of sample in embodiment 2;

Fig. 4 is the specific surface area measurement curve of sample in embodiment 1;

Fig. 5 is the low magnification scanning electron micrograph of sample in embodiment 3;

Fig. 6 is the cyclic voltammogram of the electrode obtained by sample preparation in Example 1 at different scan rates;

FIG. 7 is a graph of the cycle stability of the electrode prepared from the sample in Example 1. FIG.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings.

Example 1

Preparation of nickel oxide nanosheets:

a. Add nickel chloride hexahydrate and sodium citrate into 200mL water in a molar ratio of 1:2 and mix them thoroughly for 2 minutes to obtain a homogeneous solution.

b. Add soluble potassium tetracyanonickelate(II) into 200mL water and mix thoroughly for 2 minutes to obtain a homogeneous solution.

c. Add the solution obtained in step a to the solution in step b, and then stand at a temperature of 20° C. for 24 hours to obtain a light green precipitate growing;

d. Then centrifuge and wash the light green precipitate obtained in step c, collect and dry at 50°C for 12 hours, and finally roast at 300°C with a heating rate of 1°C/min for 1 hour to obtain light green nickel oxide Nanosheet powder.

As shown in Figure 1, the nickel oxide nanosheet that embodiment 1 obtains is characterized by X-ray powder diffractometer, and the result shows that the sample peak matches the standard spectrogram of nickel oxide (JCPDS file no.4-835, space group: Fm3m ), which shows that the experiment successfully prepared nickel oxide nanosheets; Fig. 2 is a low magnification scanning electron microscope result of Example 1 showing that the sample is a porous nickel oxide nanosheet.

As shown in FIG. 4 , calculated according to the measurement curve, the specific surface area of the nickel oxide nanosheets obtained in Example 1 is 118.2 m ² /g.

Electrochemical performance test of nickel oxide nanosheets:

Mix the nickel oxide nanosheet material obtained in Example 1 of the present invention with acetylene black and PVDF at a mass ratio of 75:15:10, and then add a little N-methylpyrrolidone (NMP) dropwise to make it evenly mixed. Press it on the treated foamed nickel to make a working electrode with an electrode area of about 1 cm ² and a thickness of about 0.2 mm. The electrochemical experimental device adopts a three-electrode system, with a saturated calomel electrode as a reference electrode, a platinum electrode (1cm×1cm) as a counter electrode, and a 1M KOH solution as a supporting electrolyte. Electrochemical tests such as discharge.

Figure 6 is the cyclic voltammetry curves of the product obtained in Example 1 at different scan rates in 1M KOH solution. It can be seen from the figure that the cyclic voltammetry curve of the material is obviously different from the nearly rectangular shape of a typical electric double layer capacitor, which indicates that the capacitance of the material mainly comes from the pseudocapacitance based on the redox process.

Fig. 7 is the charge-discharge cycle life curve of the nickel oxide active electrode of Example 1. It can also be seen from the figure that the specific capacitance of the electrode gradually decays with the increase of the number of cycles. After 500 cycles, the specific capacitance still maintains about 75% of the specific capacitance of the first cycle, showing good cycle performance.

Example 2

Preparation of nickel oxide nanosheets:

a. Add nickel chloride hexahydrate and sodium citrate into 200mL water in a molar ratio of 1:2 and mix them thoroughly for 2 minutes to obtain a homogeneous solution.

b. Add soluble potassium tetracyanonickelate(II) into 200mL water and mix thoroughly for 2 minutes to obtain a homogeneous solution.

c. Add the solution obtained in step a to the solution in step b, and then stand at a temperature of 20°C for 0.5h to obtain a light green precipitate;

d. Then centrifuge and wash the light green precipitate obtained in step c, collect and dry at 60°C for 12 hours, and finally roast at 300°C with a heating rate of 1°C/min for 1 hour to obtain light green nickel oxide Nanosheet powder.

FIG. 3 is a high-magnification transmission electron microscope image of nickel oxide nanosheets obtained in Example 2.

Example 3

Preparation of nickel oxide nanosheets:

a. Add nickel chloride hexahydrate and sodium citrate into 200mL water in a molar ratio of 1:2 and mix them thoroughly for 2 minutes to obtain a homogeneous solution.

b. Add soluble potassium tetracyanonickelate(II) into 200mL water and mix thoroughly for 2 minutes to obtain a homogeneous solution.

c. Add the solution obtained in step a to the solution in step b, and then stand at a temperature of 20° C. for 24 hours to obtain a light green precipitate growing;

d. Then centrifuge and wash the light green precipitate obtained in step c, collect and dry at 50°C for 12 hours, and finally roast at 350°C with a heating rate of 1°C/min for 0.5h to obtain light green oxide Nickel nanosheet powder.

FIG. 5 is a low-magnification scanning electron microscope image of the nickel oxide nanosheets obtained in Example 3, and the results show that the samples are porous nickel oxide nanosheets.

Example 4

Preparation of nickel oxide nanosheets:

a. Add nickel chloride hexahydrate and sodium citrate into 200mL water in a molar ratio of 1:2 and mix them thoroughly for 2 minutes to obtain a homogeneous solution.

b. Add soluble potassium tetracyanonickelate(II) into 200mL water and mix thoroughly for 2 minutes to obtain a homogeneous solution.

c. Add the solution obtained in step a to the solution in step b, and then stand at a temperature of 80° C. for 24 hours to obtain a light green precipitate;

d. Then centrifuge and wash the light green precipitate obtained in step c, collect and dry at 80°C for 12 hours, and finally roast at 300°C with a heating rate of 1°C/min for 1 hour to obtain light green nickel oxide Nanosheet powder.

Example 5

Preparation of nickel oxide nanosheets:

a. Add nickel sulfate hexahydrate and sodium citrate into 200mL water in a molar ratio of 1:2 and mix them thoroughly for 2 minutes to obtain a homogeneous solution.

b. Add soluble potassium tetracyanonickelate(II) into 200mL water and mix thoroughly for 2 minutes to obtain a homogeneous solution.

c. Add the solution obtained in step a to the solution in step b, and then stand at a temperature of 40° C. for 24 hours to obtain a light green precipitate growing;

d. Then centrifuge and wash the light green precipitate obtained in step c, collect and dry at 70°C for 12 hours, and finally roast at 300°C with a heating rate of 2°C/min for 1 hour to obtain light green nickel oxide Nanosheet powder.

Example 6

Preparation of nickel oxide nanosheets:

a. Add nickel acetate hexahydrate and sodium citrate in a molar ratio of 1:2 to 200mL water and mix them thoroughly for 2 minutes to obtain a homogeneous solution.

b. Add soluble potassium tetracyanonickelate(II) into 200mL water and mix thoroughly for 2 minutes to obtain a homogeneous solution.

c. Add the solution obtained in step a to the solution in step b, and then stand at a temperature of 30° C. for 12 hours to obtain a light green precipitate growing;

d. Then centrifuge and wash the light green precipitate obtained in step c, collect and dry at 50°C for 12 hours, and finally roast at 300°C with a heating rate of 1°C/min for 1 hour to obtain light green nickel oxide Nanosheet powder.

Example 7

Preparation of nickel oxide nanosheets:

a. Add nickel nitrate hexahydrate and sodium citrate into 200mL water in a molar ratio of 1:2 and mix them thoroughly for 2 minutes to obtain a homogeneous solution.

b. Add soluble potassium tetracyanonickelate(II) into 200mL water and mix thoroughly for 2 minutes to obtain a homogeneous solution.

c. Add the solution obtained in step a to the solution in step b, and then stand at a temperature of 30° C. for 1 hour to obtain a light green precipitate growing;

d. Then centrifuge and wash the light green precipitate obtained in step c, collect and dry at 50°C for 12 hours, and finally roast at 300°C with a heating rate of 1°C/min for 7 hours to obtain light green nickel oxide Nanosheet powder.

Claims (7)

1. a kind of preparation method of nickel oxide nano piece, it is characterised in that：Comprise the following steps：

A, soluble nickel salt, sodium citrate are proportionally added into into in water mixing after be sufficiently stirred for, obtain uniform solution,

It is sufficiently stirred for after b, mixing that solubility potassium tetracyanonickelate is added to the water, obtains uniform solution,

C, the solution solution that step a is obtained being added in step b, then in standing, obtaining growth has light green to precipitate,

D and then the light green pelleting centrifugation obtained in step c is collected, deionized water and ethanol are fully washed, products therefrom Heat preservation and dryness in vacuum drying oven is placed in, heat treatment is subsequently carried out at different temperatures, roasting had both obtained light green nickel oxide and received Rice piece powder body.

2. the preparation method of a kind of nickel oxide nano piece according to claim 1, it is characterised in that：In step a The soluble nickel salt, the mol ratio of sodium citrate are 1: 2, and in step a, the amount of water is 200mL.

3. the preparation method of a kind of nickel oxide nano piece according to claim 1, it is characterised in that：Water in step b Amount be 200mL.

4. the preparation method of a kind of nickel oxide nano piece according to claim 1, it is characterised in that：Can in step a Insoluble nickel salt is Nickel dichloride., nickel acetate, nickel nitrate or nickel sulfate.

5. the preparation method of a kind of nickel oxide nano piece according to claim 1, it is characterised in that：In step c Time of repose isDwell temperature in step c is

6. the preparation method of a kind of nickel oxide nano piece according to claim 1, it is characterised in that：It is true in step d In empty drying baker heat preservation and dryness process beTemperature environment in carry out, when a length of 12 hours.

7. the preparation method of a kind of nickel oxide nano piece according to claim 1, it is characterised in that：Heat in step d ProcessTemperature environment in carry out, ramp isAnd the time is