阅读说明：本技术 一种高比表面积缺陷型钴酸镍的制备方法 (Preparation method of high-specific-surface-area defective nickel cobaltate ) 是由 柴东凤 郭文鑫 董国华 于 2021-07-13 设计创作，主要内容包括：本发明涉及一种高比表面积缺陷型钴酸镍的制备方法。本发明的目的是要解决现有钴酸镍导电性较差和活性位点较少的问题,提供一种可同时提高其作为超级电容器电极性能和电催化析氢催化剂性能的制备方法。方法：以硝酸镍、硝酸钴、甘油和正硅酸乙酯为原料,采用自活化法,得到具有高比表面积缺陷型钴酸镍材料,为同时提高现有钴酸镍超级电容器性能和电催化析氢性能提供了一种制备方法。(The invention relates to a preparation method of high specific surface area defective nickel cobaltate. The invention aims to solve the problems of poor conductivity and few active sites of the existing nickel cobaltate, and provides a preparation method capable of simultaneously improving the performance of the nickel cobaltate as a super capacitor electrode and the performance of an electrocatalytic hydrogen evolution catalyst. The method comprises the following steps: the defect type nickel cobaltate material with high specific surface area is obtained by taking nickel nitrate, cobalt nitrate, glycerol and ethyl orthosilicate as raw materials and adopting a self-activation method, and a preparation method is provided for simultaneously improving the performance of the existing nickel cobaltate super capacitor and the electro-catalytic hydrogen evolution performance.)

1. The preparation method of the high specific surface area defective nickel cobaltate is completed according to the following steps:

(1) dissolving cobalt nitrate and nickel nitrate in isopropanol and glycerol, stirring for 2 hours at normal temperature, transferring the liquid into a polytetrafluoroethylene autoclave of 100 ml for hydrothermal reaction, naturally cooling after the reaction is finished, repeatedly washing the precipitate with deionized water, and drying to obtain the glycerol nickel cobalt microspheres;

(2) adding ethyl orthosilicate into isopropanol, stirring for a period of time at normal temperature to obtain a solution A, and dissolving 0.2 g of the precipitate prepared in the step (1) in the isopropanol, deionized water and ammonia water to obtain a solution B. Dropwise adding the solution A into the solution B, stirring for a period of time, repeatedly washing the precipitate with deionized water, and drying to obtain the glycerol nickel cobalt microspheres with the surfaces covered with silicon dioxide;

(3) putting 0.2 g of the precipitate prepared in the step (2) into a muffle furnace for calcining to obtain nickel cobaltate microspheres with the surfaces covered with silicon dioxide;

(4) placing 0.2 g of the product prepared in the step (3) into a sodium hydroxide solution for etching, repeating for three times, washing to be neutral, and drying to obtain nickel cobaltate with high specific surface area;

(5) respectively placing the nickel cobaltate and the sodium hypophosphite with high specific surface area obtained in the step (4) into two porcelain boats of a tube furnace, wherein the sodium hypophosphite is positioned at the upstream and is positioned at N₂Calcining under the protection condition to obtain the high specific surface area defective nickel cobaltate, namely the super capacitor and the electro-catalytic hydrogen evolution material.

2. The method for preparing the high specific surface area defective nickel cobaltate according to claim 1, wherein the method comprises the following steps: in the step (1), the mass of the cobalt nitrate and the nickel nitrate is 0.2-2 g, the volume of the isopropanol is 30-100 ml, the volume of the glycerol is 5-20 ml, the hydrothermal reaction temperature is 50-200 ℃, the reaction time is 5-20 hours, and the drying condition is 50-80 ℃ and 10-20 hours.

3. The method for preparing the high specific surface area defective nickel cobaltate according to claim 1, wherein the method comprises the following steps: in the step (2), the volume of the ethyl orthosilicate is 0.5-3 ml, the volume of the isopropanol in the solution A is 30-100 ml, the stirring time is 3-60 minutes, the volume of the isopropanol in the solution B is 30-100 ml, the volume of the deionized water is 50-200 ml, the volume of the ammonia water is 0.5-3 ml, the stirring time of the solution A after the solution A is dropwise added into the solution B is 5-30 hours, and the drying condition is 10-20 hours at 50-80 ℃.

4. The method for preparing the high specific surface area defective nickel cobaltate according to claim 1, wherein the method comprises the following steps: in the step (3), the calcination temperature is 300-500 ℃, the calcination time is 1-4 hours, and the drying condition is 50-80 ℃ for 10-20 hours.

5. The method for preparing the high specific surface area defective nickel cobaltate according to claim 1, wherein the method comprises the following steps: in the step (4), the etching temperature is 50-150 ℃, the etching time is 10-35 hours, and the concentration of the sodium hydroxide solution is 1-4 mol/L.

6. The method for preparing the high specific surface area defective nickel cobaltate according to claim 1, wherein the method comprises the following steps: the mass ratio of the high specific surface area defective nickel cobaltate to the sodium hypophosphite in the step (5) is 1: 5, the calcining temperature of the tubular furnace is 250-500 ℃, and the calcining time is 1-5 hours.

Technical Field

The invention relates to a preparation method of high specific surface area defective nickel cobaltate.

Background

The super capacitor is a novel energy storage device between a traditional capacitor and a battery, stores energy through rapid ion adsorption and desorption or completely reversible Faraday redox reaction at an electrode material and an electrolyte interface, is a novel energy storage device with wide development prospect, and generally takes transition metal oxide as a representative. Hydrogen (H)₂) Has proven to be an ideal energy carrier, which is produced by the Hydrogen Evolution Reaction (HER) in water electrolysis, which, among the abundant energy conversion technologies, provides a method for sustainable production of hydrogen. Currently, platinum-based materials are considered to be the most effective electrocatalytic hydrogen evolution catalysts, but their wide application is limited by the high cost. Therefore, the development of an efficient and abundant electrocatalytic hydrogen evolution catalyst is currently the focus of research.

Nickel cobaltate has more excellent electrochemical activity than monometallic nickel/cobalt oxide, but its conductivity and electrochemical active sites still need to be improved. The specific surface area of the nickel cobaltate is improved by a self-activation method, and the conductivity of the nickel cobaltate is improved and electrochemical active sites are enriched by making oxygen defects, so that the conductivity and the electrochemical performance of the nickel cobaltate are improved, and the nickel cobaltate has important research significance for solving the problem of energy shortage.

Disclosure of Invention

The invention aims to overcome the problems of poor conductivity and few reactive active sites of nickel cobaltate and provides a simple, novel and high-yield preparation method.

The preparation method of the high specific surface area defective nickel cobaltate is completed according to the following steps:

(1) dissolving cobalt nitrate and nickel nitrate in isopropanol and glycerol, stirring for 2 hours at normal temperature, transferring the liquid into a polytetrafluoroethylene autoclave of 100 ml for hydrothermal reaction, naturally cooling after the reaction is finished, repeatedly washing the precipitate with deionized water, and drying to obtain the glycerol nickel cobalt microspheres;

(2) adding ethyl orthosilicate into isopropanol, stirring for a period of time at normal temperature to obtain a solution A, and dissolving 0.2 g of the precipitate prepared in the step (1) in the isopropanol, deionized water and ammonia water to obtain a solution B. Dropwise adding the solution A into the solution B, stirring for a period of time, repeatedly washing the precipitate with deionized water, and drying to obtain the glycerol nickel cobalt microspheres with the surfaces covered with silicon dioxide;

(3) putting 0.2 g of the precipitate prepared in the step (2) into a muffle furnace for calcining to obtain nickel cobaltate microspheres with the surfaces covered with silicon dioxide;

(4) placing 0.2 g of the product prepared in the step (3) into a sodium hydroxide solution for etching, repeating for three times, washing to be neutral, and drying to obtain nickel cobaltate with high specific surface area;

(5) respectively placing the nickel cobaltate and the sodium hypophosphite with high specific surface area obtained in the step (4) into two porcelain boats of a tube furnace, wherein the sodium hypophosphite is positioned at the upstream and is positioned at N₂Calcining under the protection condition to obtain the high specific surface area defective nickel cobaltate, namely the super capacitor and the capacitorA catalytic hydrogen evolution material;

in the step (1), the mass of the cobalt nitrate and the nickel nitrate is 0.2-2 g, the volume of the isopropanol is 30-100 ml, the volume of the glycerol is 5-20 ml, the hydrothermal reaction temperature is 50-200 ℃, the reaction time is 5-20 hours, and the drying condition is 50-80 ℃ for 10-20 hours;

in the step (2), the volume of the ethyl orthosilicate is 0.5-3 ml, the volume of the isopropanol in the solution A is 30-100 ml, the stirring time is 3-60 minutes, the volume of the isopropanol in the solution B is 30-100 ml, the volume of the deionized water is 50-200 ml, the volume of the ammonia water is 0.5-3 ml, the stirring time is 5-30 hours after the solution A is dropwise added into the solution B, and the drying condition is 10-20 hours at 50-80 ℃;

in the step (3), the calcination temperature is 300-500 ℃, the calcination time is 1-4 hours, and the drying condition is 50-80 ℃ for 10-20 hours;

in the step (4), the etching temperature is 50-150 ℃, the etching time is 10-35 hours, and the concentration of the sodium hydroxide solution is 1-4 mol per liter;

the mass ratio of the high specific surface area defective nickel cobaltate to the sodium hypophosphite in the step (5) is 1: 5, the calcining temperature of the tubular furnace is 250-500 ℃, and the calcining time is 1-5 hours.

Compared with the prior art, the invention has the beneficial effects that: the defect nickel cobaltate supercapacitor with high specific surface area and the electrocatalytic hydrogen evolution material are prepared, the material with complete structure and large specific surface area can be prepared in a short time in the preparation process, in addition, the synthesis of the material does not need complex equipment, and the prepared material has excellent energy storage effect and electrocatalytic hydrogen evolution performance.

Drawings

FIG. 1 is a scanning electron micrograph (left) and a transmission electron micrograph (right) of a defective nickel cobaltate with a high specific surface area according to example 1;

FIG. 2 is a powder X-ray diffraction pattern of the high specific surface area defective nickel cobaltate of example 1;

FIG. 3 is a drawing showing the nitrogen desorption of the high specific surface area defective nickel cobaltate of example 1;

FIG. 4 is a constant current charge and discharge diagram of the high specific surface area defective nickel cobaltate of example 1;

FIG. 5 is a linear cyclic voltammogram of the high specific surface area deficient nickel cobaltate of example 1.

Detailed Description

The technical solution of the present invention is not limited to the specific embodiments listed below, which are only used for illustrating the present invention and are not limited to the technical solutions described in the embodiments of the present invention. It will be appreciated by those skilled in the art that the present invention may be modified or substituted equally as well to achieve the same technical result. So long as the use requirements are met, the invention is within the protection scope.

The preparation method of the high specific surface area defective nickel cobaltate of the embodiment is completed according to the following steps:

(1) dissolving 0.291 g of cobalt nitrate and 0.291 g of nickel nitrate in 45 ml of isopropanol and 8 ml of glycerol, stirring for 2 hours at normal temperature, transferring the liquid into a 100 ml of polytetrafluoroethylene autoclave, carrying out hydrothermal reaction at 120 ℃ for 16 hours, naturally cooling after the reaction is finished, repeatedly washing the precipitate with deionized water, and drying at 60 ℃ for 12 hours to obtain the cobaltous glycerol microspheres;

(2)1 ml of ethyl orthosilicate was added to 40 ml of isopropanol and stirred for 20 minutes to obtain solution A, and 0.2 g of the precipitate prepared in step (1) was dissolved in 40 ml of isopropanol, 80 ml of deionized water and 1 ml of ammonia water and stirred for 20 minutes to obtain solution B. Dropwise adding the solution A into the solution B, stirring for 24 hours, repeatedly washing the precipitate with deionized water, and drying at 60 ℃ for 12 hours to obtain the cobalt glycerol microspheres with the surfaces covered with silicon dioxide;

(3) putting 0.2 g of the precipitate prepared in the step (2) into a muffle furnace, and calcining for 2 hours at 400 ℃ to obtain nickel cobaltate microspheres with the surfaces covered with silicon dioxide;

(4) and (3) putting 0.2 g of the product prepared in the step (3) into a sodium hydroxide solution of 2 mol/L at 85 ℃, stirring for 24 hours, and repeating for three times to obtain the high specific surface area defective nickel cobaltate, namely the supercapacitor and the electrocatalytic hydrogen evolution material. (5) 0.1 g of cobalt acid with high specific surface area obtained in the step (4)Nickel and 0.5 g of sodium hypophosphite were placed in two porcelain boats of a tube furnace, respectively, with the sodium hypophosphite upstream, N₂Calcining for 1 hour at 250 ℃ under the protection condition to obtain the high specific surface area defective nickel cobaltate.

The invention is further described with reference to the following drawings and examples:

FIG. 1 is a scanning electron microscope (left image) and a transmission electron microscope (right image) of the high specific surface area deficient nickel cobaltate of example 1. The defect nickel cobaltate with high specific surface area is in an irregular spherical shape and is caused by irregular movement of gas generated in the self-activation process in the silicon dioxide shell.

FIG. 2 is a powder X-ray diffraction pattern of the high specific surface area defective nickel cobaltate of example 1. Diffraction peaks at positions 31.0, 38.5, 44.7, 56.2, 59.3 and 65.8 correspond to the (220), (311), (400), (422), (511) and (440) crystal planes (JCPDS No.20-0781), indicating that the product is nickel cobaltate.

FIG. 3 is a drawing showing the nitrogen gettering of the high specific surface area defective nickel cobaltate of example 1. Wherein, 0-0.2P/P₀The absence of protrusions indicates that the material is not microporous, 0.4P/P₀The existence of mesopores, 1P/P, is shown by the presence of hysteresis loop₀There is still an upward trend after that indicating the presence of large pores in the material. Thus, the defect nickel cobaltate after self-activation has 168.04m²The specific surface area per gram is higher than that of the defect nickel cobaltate without self-activation of the control group (55.39 m)²Specific surface area of glycerol nickel cobalt (74.80 m)²/g)。

FIG. 4 is a constant current charge and discharge diagram of example 1, defective nickel cobaltate with high specific surface area. Under different current densities, the charge and discharge capacities of the electrode material are approximately equal, which shows that the material has excellent reversibility and coulombic efficiency; at a current density of 0.5A/g, the high specific surface area defective nickel cobaltate has a specific capacitance of up to 1495.2F/g, indicating that the material has excellent supercapacitor performance.

FIG. 5 is a linear cyclic voltammogram of the high specific surface area deficient nickel cobaltate of example 1. At 10mA/cm²The overpotential of the nickel cobaltate with high specific surface area is 169.8mV, which indicates that the target productHas excellent electrocatalytic hydrogen evolution performance.