CN110444779B - Preparation method of Co-LDH zinc air battery catalyst with sheet structure - Google Patents

Preparation method of Co-LDH zinc air battery catalyst with sheet structure Download PDF

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CN110444779B
CN110444779B CN201910684511.2A CN201910684511A CN110444779B CN 110444779 B CN110444779 B CN 110444779B CN 201910684511 A CN201910684511 A CN 201910684511A CN 110444779 B CN110444779 B CN 110444779B
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ldh
air battery
battery catalyst
zinc
sheet structure
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CN110444779A (en
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杨林
谷佳莉
王荷
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Henan Normal University
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Henan Normal University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/9016—Oxides, hydroxides or oxygenated metallic salts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M12/00—Hybrid cells; Manufacture thereof
    • H01M12/04—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type
    • H01M12/06—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type with one metallic and one gaseous electrode

Abstract

The invention discloses a preparation method of a Co-LDH zinc air battery catalyst with a sheet structure, which comprises the steps of dissolving cobalt acetate and hydrazine in distilled water, transferring the solution to a reaction kettle, keeping the temperature at 120 ℃ for 6h, washing for a plurality of times, and drying to obtain Co (OH)2And dispersing the mixture in an alcohol solution to obtain a standby solution, adding dimethyl imidazole, transferring the reaction solution into a reaction kettle after chelating balance is achieved, keeping the temperature at 100 ℃ for 16 hours, washing the reaction product for several times, and drying to obtain the Co-LDH zinc air battery catalyst with the thickness of 5-10nm and a sheet structure. The bifunctional electrocatalyst with the core-shell structure has larger specific surface area, more exposed active sites, better contact with electrolyte and effectively improved electrocatalytic activity.

Description

Preparation method of Co-LDH zinc air battery catalyst with sheet structure
Technical Field
The invention belongs to the technical field of zinc-air battery catalysts, and particularly relates to a preparation method of a Co-LDH zinc-air battery catalyst with a sheet structure.
Background
The zinc-air battery as a clean energy has the advantages of high specific energy, low cost, no pollution and the like, has experimental application in many fields, and becomes a hot spot of research in recent years. In zinc-air cells, the catalyst is the core component and is also the key material determining the cost and performance of the cell. In recent years, there has been a lot of research on zinc-air battery catalysts, however, the synthesis of ORR and OER bifunctional electrocatalysts remains challenging. Therefore, the development of a bifunctional electrocatalyst becomes one of the important problems to be solved in the technical field of zinc-air battery catalyst synthesis.
Recently, the synthesis of many transition metal-based electrocatalysts, such as transition metal hydroxides, has been realized, which have attracted much attention due to their high intrinsic activity, perfect stability, and excellent conductivity to be applied to OER reactions. The transition metal hydroxide has large specific surface area, more exposed active sites, better contact with electrolyte and good OER performance, but is unstable and easy to agglomerate, and the application of the transition metal hydroxide is limited by the defects.
Metal Organic Frameworks (MOFs) are crystalline materials formed by self-assembly of inorganic metals and organic ligands, and have attracted extensive attention due to a series of superior properties such as diverse structures, adjustable pore sizes, modifiable frameworks, and adjustable performance. The derivative and the derivative thereof have great potential in the aspect of electrocatalysis application, and are used as bifunctional electrocatalysts to be deeply researched. The variability of its structure facilitates the direct conversion of ZIF-67 to metal hydroxides. By selecting ZIF-67 as a cobalt source and preparing Co-LDH from a sacrificial template, the ORR/OER performance and stability of the Co-LDH can be improved.
Disclosure of Invention
The invention solves the technical problem of providing a preparation method of the Co-LDH zinc air battery catalyst with a sheet structure, which has the advantages of simple operation, mild reaction condition, higher reaction efficiency and lower energy consumption.
The invention adopts the following technical scheme for solving the technical problems, and the preparation method of the Co-LDH zinc air battery catalyst with the sheet structure is characterized by comprising the following specific steps:
step S1: dissolving cobalt acetate and hydrazine in distilled water, stirring at 25 ℃ for 10min to obtain a uniform stable solution, transferring the uniform stable solution into a stainless steel reaction kettle with a polytetrafluoroethylene lining, keeping the temperature at 120 ℃ for 6h, naturally cooling the reaction kettle to room temperature, washing the reaction product for a plurality of times, and drying to obtain Co (OH)2Then adding Co (OH)2Ultrasonic dispersing in alcohol solution to obtain Co (OH)2A stock solution;
step S2: to Co (OH) obtained in step S12Adding dimethyl imidazole into the standby solution, transferring the reaction solution into a stainless steel reaction kettle with a polytetrafluoroethylene lining after chelation balance is achieved, keeping the temperature at 100 ℃ for 16 hours, naturally cooling the reaction kettle to room temperature, washing the reaction product for a plurality of times, and drying in vacuum to obtain a Co-LDH zinc air battery catalyst with a sheet structure and the thickness of 5-10 nm;
the Co-LDH zinc air battery catalyst shows higher OER and ORR dual-function electrocatalytic activity, the Co-LDH zinc air battery catalyst with the sheet structure can provide an ideal solid-liquid-gas three-phase region for electrode reaction, more channels are provided for the transmission of electrolyte, the specific surface area of the zinc air battery catalyst is further improved, the catalytic activity of the zinc air battery catalyst is increased, a target product is obtained under the non-calcination condition, the collapse of pore channels caused by calcination is avoided, the variation of the Co-LDH structure caused by calcination is avoided, and the tendency of electrical property attenuation is restrained.
Preferably, the feeding mass ratio of the cobalt acetate to the hydrazine in the step S1 is 1:5-5: 1.
Preferably, the alcohol solution in step S1 is methanol, ethanol or isopropanol.
Preferably, the Co (OH) in step S22The feeding mass ratio of the imidazole and the dimethyl imidazole is 1:25-25: 1.
Compared with the prior art, the invention has the following beneficial effects:
1. the synthetic method of the Co-LDH bifunctional electrocatalyst with a sheet structure has the advantages of simple operation, mild reaction conditions, high reaction efficiency and low energy consumption;
2. the Co-LDH zinc-air battery catalyst prepared by the invention has larger specific surface area and more exposed active sites, can be in better contact with electrolyte, and can effectively improve the electrocatalytic activity of the zinc-air battery catalyst;
3. in the invention, diamine is used for providing an alkaline environment, which plays a guiding role in the synthesis of the Co-LDH zinc air battery catalyst and effectively ensures the formation of the Co-LDH zinc air battery catalyst with a sheet structure;
4. the Co-LDH zinc-air battery catalyst with the sheet structure, which is synthesized by the invention, has the sheet structure, realizes that the Co-LDH composite material has the electrocatalytic activity with the OER and ORR double functions under the non-calcination condition, and has wide application prospect in zinc-air batteries.
Drawings
FIG. 1 is a SEFEM diagram of a two-dimensional nanosheet Co-LDH zinc air cell catalyst prepared in example 1;
FIG. 2 is an SEM image of a two-dimensional nanosheet Co-LDH zinc air cell catalyst prepared in example 2;
FIG. 3 is a graph showing the electrochemical properties of the products obtained in example 1 and comparative example 1 and commercial CoO.
Detailed Description
The present invention is described in further detail below with reference to examples, but it should not be construed that the scope of the above subject matter of the present invention is limited to the following examples, and that all the technologies realized based on the above subject matter of the present invention belong to the scope of the present invention.
Example 1
Dissolving 0.249g of cobalt acetate and 0.125g of hydrazine in 30mL of distilled water, stirring for 10min at 25 ℃, finally transferring the solution into a stainless steel autoclave with a polytetrafluoroethylene lining, keeping the temperature at 120 ℃ for 6h, naturally cooling the autoclave to room temperature, washing the autoclave with secondary water for a plurality of times, and then putting the cooled autoclave into an oven to dry for 12h to obtain a pink intermediate product Co (OH)2(ii) a 40mg of the above-mentioned pink intermediate Co (OH)2Ultrasonically dispersing in 60mL of methanol solution, adding 0.985g of dimethyl imidazole after uniform dispersion, stirring for 30min, transferring into a reaction kettle with a polytetrafluoroethylene lining, keeping at 100 ℃ for 16h, washing for several times by using methanol after the reaction is finished, and drying in a vacuum drying oven to obtain the light purple Co-LDH zinc air battery catalyst. As can be seen from FIG. 1, the Co-LDH electrocatalyst prepared by the present example has a two-dimensional nano-sheet structure, and the thickness of the Co-LDH electrocatalyst is between 5 and 10 nm.
2mg of the Co-LDH zinc air battery catalyst prepared in the embodiment is dispersed in an ethanol dispersant, carbon black is added, the mixed solution is ultrasonically and uniformly coated on the surface of a glassy carbon electrode, a three-electrode system is adopted, the performance of the catalyst is measured through an electrochemical workstation, and the test result of the electrical performance is shown in figure 3.
Example 2
Dissolving 0.249g of cobalt acetate and 0.063g of hydrazine in 30mL of distilled water, stirring at 25 ℃ for 10min, transferring to a stainless steel autoclave with a polytetrafluoroethylene lining, keeping at 120 ℃ for 6h, naturally cooling the reaction kettle to room temperature, washing with secondary water for several times, and drying in an oven for 12h to obtain a pink intermediate product Co (OH)240mg of the above pink intermediate productCo(OH)2Ultrasonically dispersing in 60mL of methanol solution, adding 0.985g of dimethyl imidazole after uniform dispersion, stirring for 30min, transferring into a reaction kettle with a polytetrafluoroethylene lining, keeping at 100 ℃ for 16h, washing for several times by using methanol after the reaction is finished, and drying in a vacuum drying oven to obtain the light purple Co-LDH zinc air battery catalyst.
Example 3
Dissolving 0.249g of cobalt acetate and 0.125g of hydrazine in 30mL of distilled water, stirring for 10min at 25 ℃, finally transferring the solution into a stainless steel autoclave with a polytetrafluoroethylene lining, keeping the temperature at 120 ℃ for 6h, naturally cooling the autoclave to room temperature, washing the autoclave with secondary water for a plurality of times, and then putting the cooled autoclave into an oven to dry for 12h to obtain a pink intermediate product Co (OH)240mg of the above-mentioned pink intermediate Co (OH)2Ultrasonically dispersing in 60mL of methanol solution, adding 0.493g of dimethyl imidazole after uniform dispersion, stirring for 30min, transferring into a polytetrafluoroethylene hydrothermal kettle, keeping at 100 ℃ for 16h, washing for several times by using methanol after the reaction is finished, and drying in a vacuum drying oven to obtain the light purple Co-LDH zinc air battery catalyst.
Example 4
Dissolving 0.249g of cobalt acetate and 0.125g of hydrazine in 30mL of distilled water, stirring for 10min at 25 ℃, finally transferring the solution into a stainless steel autoclave with a polytetrafluoroethylene lining, keeping the temperature at 120 ℃ for 6h, naturally cooling the autoclave to room temperature, washing the autoclave with secondary water for a plurality of times, and then putting the cooled autoclave into an oven to dry for 12h to obtain a pink intermediate product Co (OH)240mg of the above-mentioned pink intermediate Co (OH)2Ultrasonically dispersing in 60mL of absolute ethanol solution, adding 0.985g of dimethyl imidazole after uniform dispersion, stirring for 30min, transferring into a reaction kettle with a polytetrafluoroethylene lining, keeping at 100 ℃ for 16h, washing with methanol for several times after the reaction is finished, and drying in a vacuum drying oven to obtain the light purple Co-LDH zinc air battery catalyst.
Example 5
Dissolving 0.249g of cobalt acetate and 0.267g of hydrazine in 30mL of distilled water, stirring at 25 ℃ for 10min, transferring into a stainless steel autoclave with a polytetrafluoroethylene lining, keeping at 120 ℃ for 6h, naturally cooling the autoclave to room temperature, washing with secondary water for several times, and then placingDrying in an oven for 12h to give a pink intermediate Co (OH)240mg of the above-mentioned pink intermediate Co (OH)2Ultrasonically dispersing in 60mL isopropanol solution, adding 0.985g of dimethyl imidazole after uniform dispersion, stirring for 30min, transferring into a reaction kettle with a polytetrafluoroethylene lining, keeping at 100 ℃ for 16h, washing with methanol for several times after the reaction is finished, and drying in a vacuum drying oven to obtain the light purple Co-LDH zinc air battery catalyst.
Comparative example 1
Dissolving 0.249g of cobalt acetate and 0.125g of hydrazine in 30mL of distilled water, stirring for 10min at 25 ℃, finally transferring the solution into a stainless steel autoclave with a polytetrafluoroethylene lining, keeping the temperature at 120 ℃ for 6h, naturally cooling the autoclave to room temperature, washing the autoclave with secondary water for a plurality of times, and then putting the cooled autoclave into an oven to dry for 12h to obtain a pink intermediate product Co (OH)2。
2mg of Co (OH) prepared in this comparative example were taken2Dispersing the catalyst in an ethanol dispersant, adding carbon black, coating the mixed solution on the surface of a glassy carbon electrode after ultrasonic homogenization, measuring the performance of the catalyst by an electrochemical workstation by adopting a three-electrode system, and testing the electrical performance, wherein the result is shown in figure 3.
The zinc-air battery catalyst prepared by the invention has good OER and ORR dual-function electrocatalytic activity. In fig. 3, in the electrical property test results, a is the ORR polarization curve of the catalysts prepared in example 1 and comparative example 1, and b is the OER polarization curve of the catalysts prepared in example 1 and comparative example 1, compared with comparative example 1, the zinc-air battery catalyst prepared in example 1 shows higher OER and ORR dual-functional electrocatalytic activity; the Co-LDH zinc air battery catalyst with the sheet structure can provide an ideal solid-liquid-gas three-phase region for electrode reaction, provides more channels for the transmission of electrolyte, further improves the specific surface area of the zinc air battery catalyst, increases the catalytic activity of the electrocatalyst, obtains a target product under the non-calcination condition, avoids pore channel collapse caused by calcination, avoids Co-LDH structure variation caused by calcination, and suppresses the tendency of electrical property attenuation.
The foregoing embodiments illustrate the principles, principal features and advantages of the invention, and it will be understood by those skilled in the art that the invention is not limited to the foregoing embodiments, which are merely illustrative of the principles of the invention, and that various changes and modifications may be made therein without departing from the scope of the principles of the invention.

Claims (4)

1. A preparation method of a Co-LDH zinc air battery catalyst with a sheet structure is characterized by comprising the following specific steps:
step S1: dissolving cobalt acetate and hydrazine in distilled water, stirring at 25 ℃ for 10min to obtain a uniform stable solution, transferring the uniform stable solution into a stainless steel reaction kettle with a polytetrafluoroethylene lining, keeping the temperature at 120 ℃ for 6h, naturally cooling the reaction kettle to room temperature, washing the reaction product for a plurality of times, and drying to obtain Co (OH)2Then adding Co (OH)2Ultrasonic dispersing in alcohol solution to obtain Co (OH)2A stock solution;
step S2: to Co (OH) obtained in step S12Adding dimethyl imidazole into the standby solution, transferring the reaction solution into a stainless steel reaction kettle with a polytetrafluoroethylene lining after chelation balance is achieved, keeping the temperature at 100 ℃ for 16 hours, naturally cooling the reaction kettle to room temperature, washing the reaction product for a plurality of times, and drying in vacuum to obtain a Co-LDH zinc air battery catalyst with a sheet structure and the thickness of 5-10 nm;
the Co-LDH zinc air battery catalyst shows higher OER and ORR dual-function electrocatalytic activity, the Co-LDH zinc air battery catalyst with the sheet structure can provide an ideal solid-liquid-gas three-phase region for electrode reaction, more channels are provided for the transmission of electrolyte, the specific surface area of the zinc air battery catalyst is further improved, the catalytic activity of the zinc air battery catalyst is increased, a target product is obtained under the non-calcination condition, the collapse of pore channels caused by calcination is avoided, the variation of the Co-LDH structure caused by calcination is avoided, and the tendency of electrical property attenuation is restrained.
2. The method for preparing a Co-LDH zinc-air battery catalyst of a sheet structure as claimed in claim 1, wherein: in the step S1, the feeding mass ratio of the cobalt acetate to the hydrazine is 1:5-5: 1.
3. The method for preparing a Co-LDH zinc-air battery catalyst of a sheet structure as claimed in claim 1, wherein: the alcohol solution in step S1 is methanol, ethanol or isopropanol.
4. The method for preparing a Co-LDH zinc-air battery catalyst of a sheet structure as claimed in claim 1, wherein: co (OH) described in step S22The feeding mass ratio of the imidazole and the dimethyl imidazole is 1:25-25: 1.
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