A cobalt-manganese bimetallic oxide oer catalyst and application thereof in zinc-air battery

Abstract

The application relates to the technical field of oxygen evolution reaction, and discloses a cobalt-manganese bimetallic oxide OER (oxygen evolution reaction) catalyst and application thereof in zinc-air batteries, wherein water, a cobalt salt, a manganese salt and a polyethylene glycol copolymer are added into a hydrothermal reaction kettle, a precipitant is added after stirring, reaction is carried out, the product is calcined in a resistance furnace, and the cobalt-manganese bimetallic oxide OER catalyst is obtained. The OER catalyst is composed of cobalt-manganese bimetallic oxide and a nitrogen-sulfur doped carbon matrix. After being doped with nitrogen and sulfur, the carbon matrix has better conductivity, and the wettability with an electrolyte is increased, which is beneficial to accelerating the migration and diffusion of electrons and ions in the oxygen evolution reaction. Meanwhile, catalytic active centers such as pyridine nitrogen and pyrrole nitrogen are formed, the oxygen evolution reaction is promoted, the specific surface area is higher, more oxygen evolution reaction active sites are exposed, and the oxygen evolution reaction catalytic activity is better.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of oxygen evolution reaction, in particular to a cobalt-manganese bimetallic oxide OER catalyst and application thereof in a zinc-air battery. BACKGROUND

[0002] The zinc-air battery has the advantages of small volume, light mass, large charge capacity and the like, and is a green and environmentally-friendly battery with great development prospect. Two most important reactions in the zinc-air battery are an ORR oxygen reduction reaction and an OER oxygen evolution reaction. The energy barrier in the OER oxygen evolution reaction process is large, and the electrochemical reaction rate and efficiency are low, which affects the electrochemical performance of the zinc-air battery. At present, the OER oxygen evolution reaction mainly uses a noble metal catalyst such as platinum and ruthenium, and development of a cheap and easily-obtained transition metal catalyst is a research hotspot.

[0003] The cobalt-manganese oxide has a bimetallic catalytic active center, and has the advantages of various preparation methods, controllable structure and wide raw material sources, and is widely researched in OER oxygen evolution catalysts. Patent CN110508308B discloses a preparation method and application of a CoMn-P-NCNT multifunctional catalyst, and uses a cobalt salt, a manganese salt, ammonium fluoride, a phosphorus source, dopamine hydrochloride, urea and the like as raw materials, realizes nitrogen and phosphorus element-doped carbon nanotube coated cobalt atom particles, and manganese oxide is attached around the carbon nanotube, so that the obtained catalyst has good OER, ORR and the like catalytic activity. Increasing the specific surface area of the catalyst, and doping the carbon-based carrier of the catalyst with nitrogen, sulfur and the like can improve the OER oxygen evolution reaction activity of the catalyst. SUMMARY

[0004] The technical problem solved by the application is to provide a cobalt-manganese bimetallic oxide OER catalyst with large specific surface area and high catalytic activity for application in a zinc-air battery.

[0005] The technical scheme is a preparation method of a cobalt-manganese bimetallic oxide OER catalyst:

[0006] Step A, a flask equipped with a water separator is added with dimethylbenzene, polyethylene glycol, 2-thiophenyl naphthalene dicarboxylic acid imide and p-toluenesulfonic acid, and stirred at 110-130 DEG C for 2-3 h, rotary evaporation, methanol washing, drying, and polyethylene glycol copolymer is obtained.

[0007] Step B, add water, cobalt salt, manganese salt, polyethylene glycol copolymer into the hydrothermal reactor, after stirring, add precipitator, react at 100-120℃ for 12-18h, after cooling, filter, wash with ethanol and water in turn, dry the product, first heat to 280-300℃ in air atmosphere, keep heat for 2-3h, then heat to 600-700℃ in nitrogen atmosphere, keep heat for 1.5-2.5h, cool, get cobalt-manganese bimetallic oxide OER catalyst. The preparation reaction formula is as follows:

[0008] .

[0009] In step A, the ratio of polyethylene glycol, 2-thiophenyl naphthalene dicarboxylic acid imide, p-toluenesulfonic acid is 1mol:(1-1.2)mol:(0.002-0.003)mol.

[0010] In step B, the ratio of cobalt salt, manganese salt, polyethylene glycol copolymer, precipitator is 2mol:1mol:(300-600)g:(5-8)mol.

[0011] In step B, the ratio of cobalt salt, manganese salt, polyethylene glycol copolymer, precipitator is 2mol:1mol:(300-600)g:(5-8)mol.

[0012] In step B, the ratio of cobalt salt, manganese salt, polyethylene glycol copolymer, precipitator is 2mol:1mol:(300-600)g:(5-8)mol.

[0013] In step B, the ratio of cobalt salt, manganese salt, polyethylene glycol copolymer, precipitator is 2mol:1mol:(300-600)g:(5-8)mol.

[0014] .

[0015] In step B, the ratio of cobalt salt, manganese salt, polyethylene glycol copolymer, precipitator is 2mol:1mol:(300-600)g:(5-8)mol.

[0016] Technical effects: the polyethylene glycol copolymer containing naphthalene diimide and thiophene structure is obtained by esterification polymerization reaction of 2-thiophenyl carboxylic acid naphthalene diimide and polyethylene glycol, the polyethylene glycol copolymer is used as a surfactant and a structure directing agent, cobalt chloride or cobalt nitrate is used as a cobalt salt, manganese chloride or manganese nitrate is used as a manganese source, hexamethylenetetramine is used as a precipitator, a cobalt-manganese precursor is generated through hydrothermal reaction, then in the high-temperature calcination process, the naphthalene diimide ring with high carbonization and rigidity is used as a carbon source and a nitrogen source, and the thiophene is used as a sulfur source, the carbon matrix co-doped with nitrogen and sulfur is generated through calcination and carbonization, the cobalt-manganese precursor generates cobalt-manganese bimetal oxide MnCo2O4 and is loaded into the carbon matrix, meanwhile, the polyethylene glycol copolymer plays a role of a structure directing agent, the cobalt-manganese bimetal oxide forms a regular porous nanoflower structure, has good dispersibility and a larger specific surface area, and is beneficial to improve the OER oxygen reduction catalytic active site.

[0017] The OER catalyst of the present application is composed of cobalt-manganese bimetal oxide and nitrogen-sulfur doped carbon matrix, after the carbon matrix is co-doped with nitrogen and sulfur, the conductivity is better, the wettability with electrolyte is increased, which is beneficial to accelerate the migration and diffusion of electrons and ions in the oxygen evolution reaction, at the same time, catalytic active centers such as pyridine nitrogen and pyrrole nitrogen are formed, the oxygen evolution reaction is promoted, and the OER catalyst has a higher specific surface area, exposes more oxygen evolution reaction active sites, and thus has better oxygen evolution reaction catalytic activity. The overpotential of only 193-231 mV can reach a current density of 10 mA / cm 2 , and the Tafel slope value is only 60.8-73.7 mV / dec. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a scanning electron microscope image of the cobalt-manganese bimetal oxide OER catalyst. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0020] Example 1:

[0021] (1) A flask equipped with a condenser reflux tube was charged with 50 mL of N,N-dimethylformamide, 8 mmol of 1,4,5,8-naphthalenetetracarboxylic anhydride, 20.8 mmol of 5-aminothiophene-2-carboxylic acid methyl ester, and 24 mmol of triethylamine. The reaction was stirred at 135°C under a nitrogen atmosphere for 6 h. The solution was diluted with water, filtered, and the filter cake was washed with acetone. The dried product was added to 150 mL of methanol, and 100 mL of a 3.5 mol / L potassium hydroxide solution was added. The reaction was stirred at 95°C under a condenser reflux for 4 h. After cooling, hydrochloric acid solution was slowly added dropwise, and the mixture was stirred until a large amount of precipitate was formed. The mixture was filtered, washed with water, and dried to obtain 2-thiophenyl naphthalene dicarboxylic acid imide.

[0022] (2) A flask equipped with a water separator was charged with 20 mL of xylene, 10 mmol of polyethylene glycol 2000, 10 mmol of 2-thiophenyl naphthalene dicarboxylic acid imide, and 0.02 mmol of p-toluenesulfonic acid. The reaction was stirred at 120°C for 3 h, rotary evaporated, washed with methanol, and dried to obtain a polyethylene glycol copolymer.

[0023] (3) A hydrothermal reaction kettle was charged with 3 L of water, 60 mmol of cobalt chloride, 30 mmol of manganese chloride, and 9 g of the polyethylene glycol copolymer. After stirring, 170 mmol of the precipitant hexamethylenetetramine was added. The reaction was stirred at 110°C for 18 h. After cooling, the mixture was filtered, washed with ethanol and water, and dried. The product was calcined in an electric resistance furnace under an air atmosphere at 280°C for 4 h, and then under a nitrogen atmosphere at 650°C for 2 h. After cooling, a cobalt-manganese bimetallic oxide OER catalyst was obtained.

[0024] Example 2:

[0025] (1) A flask equipped with a condenser reflux tube was charged with 50 mL of N,N-dimethylformamide, 8 mmol of 1,4,5,8-naphthalenetetracarboxylic anhydride, 17.6 mmol of 5-aminothiophene-2-carboxylic acid methyl ester, and 20 mmol of triethylamine. The reaction was stirred at 120°C under a nitrogen atmosphere for 12 h. The solution was diluted with water, filtered, and the filter cake was washed with acetone. The dried product was added to 150 mL of methanol, and 120 mL of a 4 mol / L potassium hydroxide solution was added. The reaction was stirred at 85°C under a condenser reflux for 6 h. After cooling, hydrochloric acid solution was slowly added dropwise, and the mixture was stirred until a large amount of precipitate was formed. The mixture was filtered, washed with water, and dried to obtain 2-thiophenyl naphthalene dicarboxylic acid imide.

[0026] (2) A flask equipped with a water separator was charged with 30 mL of xylene, 10 mmol of polyethylene glycol 2000, 12 mmol of 2-thiophenyl naphthalene dicarboxylic acid imide, and 0.03 mmol of p-toluenesulfonic acid. The reaction was stirred at 110°C for 12 h, rotary evaporated, washed with methanol, and dried to obtain a polyethylene glycol copolymer.

[0027] (3) Into a hydrothermal reactor, 4 L of water, 60 mmol of cobalt nitrate, 30 mmol of manganese nitrate, and 12 g of the polyethylene glycol copolymer were added. After stirring, 150 mmol of the precipitant hexamethylenetetramine was added. The reaction was carried out at 100°C for 18 h. After cooling, the product was filtered, washed with ethanol and water in sequence, and dried. The product was calcined in an electric resistance furnace, first in an air atmosphere, at a temperature of 300°C for 3 h, and then in a nitrogen atmosphere, at a temperature of 600°C for 2.5 h. After cooling, a cobalt-manganese bimetallic oxide OER catalyst was obtained.

[0028] Example 3:

[0029] (1) Into a flask equipped with a water separator, 30 mL of xylene, 10 mmol of polyethylene glycol 2000, 12 mmol of 2-thiophenyl naphthalene dicarboxylic acid formic acid, and 0.023 mmol of p-toluenesulfonic acid were added. The reaction was carried out at 110°C for 3 h with stirring. After rotary evaporation, methanol washing, and drying, a polyethylene glycol copolymer was obtained.

[0030] (2) Into a hydrothermal reactor, 4 L of water, 60 mmol of cobalt nitrate, 30 mmol of manganese nitrate, and 15 g of the polyethylene glycol copolymer were added. After stirring, 150 mmol of the precipitant hexamethylenetetramine was added. The reaction was carried out at 100°C for 18 h. After cooling, the product was filtered, washed with ethanol and water in sequence, and dried. The product was calcined in an electric resistance furnace, first in an air atmosphere, at a temperature of 280°C for 3 h, and then in a nitrogen atmosphere, at a temperature of 600°C for 2.5 h. After cooling, a cobalt-manganese bimetallic oxide OER catalyst was obtained.

[0031] Example 4:

[0032] (1) Into a flask equipped with a water separator, 20 mL of xylene, 10 mmol of polyethylene glycol 2000, 11 mmol of 2-thiophenyl naphthalene dicarboxylic acid formic acid, and 0.026 mmol of p-toluenesulfonic acid were added. The reaction was carried out at 130°C for 2 h with stirring. After rotary evaporation, methanol washing, and drying, a polyethylene glycol copolymer was obtained.

[0033] (2) Into a hydrothermal reactor, 5 L of water, 60 mmol of cobalt chloride, 30 mmol of manganese chloride, and 18 g of the polyethylene glycol copolymer were added. After stirring, 240 mmol of the precipitant urea was added. The reaction was carried out at 110°C for 12 h. After cooling, the product was filtered, washed with ethanol and water in sequence, and dried. The product was calcined in an electric resistance furnace, first in an air atmosphere, at a temperature of 280°C for 3 h, and then in a nitrogen atmosphere, at a temperature of 700°C for 1.5 h. After cooling, a cobalt-manganese bimetallic oxide OER catalyst was obtained.

[0034] Comparative Example 1:

[0035] (1) Into a hydrothermal reactor, 3 L of water, 60 mmol of cobalt chloride, 30 mmol of manganese chloride, 9 g of polyethylene glycol 2000 were added, and after stirring, 170 mmol of precipitant hexamethylenetetramine was added. The mixture was reacted at 110°C for 18 h. After cooling, the product was filtered, washed with ethanol and water in sequence, and dried. The product was calcined in a resistance furnace, first in an air atmosphere, heated to 280°C, and kept for 4 h; then in a nitrogen atmosphere, heated to 650°C, and kept for 2 h. After cooling, the cobalt-manganese bimetallic oxide OER catalyst was obtained.

[0036] Comparative Example 2:

[0037] (1) Into a hydrothermal reactor, 3 L of water, 60 mmol of cobalt chloride, 30 mmol of manganese chloride, 9 g of polyethylene glycol 2000 were added, and after stirring, 170 mmol of precipitant hexamethylenetetramine was added. The mixture was reacted at 110°C for 18 h. After cooling, the product was filtered, washed with ethanol and water in sequence, and dried. The product was calcined in a resistance furnace, first in an air atmosphere, heated to 280°C, and kept for 4 h; then in a nitrogen atmosphere, heated to 650°C, and kept for 2 h. After cooling, the cobalt-manganese bimetallic oxide OER catalyst was obtained.

[0038] The specific surface area of the cobalt-manganese bimetallic oxide OER catalyst was determined by nitrogen adsorption-desorption method using a specific surface and porosity analyzer. The electrode material was vacuum degassed at 150°C for 12 h before testing.

[0039] Table 1 Specific surface area test

[0040]

[0041] Figure 1 The scanning electron microscope image of Example 1 and Comparative Example 2 shows that the cobalt-manganese bimetallic oxide OER catalyst obtained by using polyethylene glycol copolymer and polyethylene glycol as surfactant and structure directing agent respectively presents a regular porous nanoflower structure and good dispersibility, and has a larger specific surface area, which is beneficial to improve the catalytic active site. The cobalt-manganese bimetallic oxide OER catalyst of Comparative Example 1 presents irregular agglomerates and has a small specific surface area.

[0042] The cobalt-manganese bimetallic oxide OER catalyst was added to ethanol and ultrasonically dispersed, then Nafion solution was added, and the slurry was coated on the surface of a glassy carbon electrode. The catalyst loading was 0.5 mg / cm 2 A platinum electrode was used as a counter electrode, and an Ag / AgCl electrode was used as a reference electrode. The electrolyte was 0.1 mol / L potassium hydroxide solution. The oxygen evolution reaction activity test was carried out in an electrochemical workstation. The scanning rate was 10 mV / s.

[0043] Table 2 Oxygen evolution reaction activity test

[0044]

[0045] The cobalt-manganese bimetallic oxide OER catalysts of embodiments 1-4 only require an overpotential of 193-231 mV to reach a current density of 10 mA / cm 2 , and the Tafel slope value is only 60.8-73.7 mV / dec, which is significantly lower than that of comparative examples 1 and 2. This is because the OER catalysts of embodiments 1-4 are composed of cobalt-manganese bimetallic oxide and nitrogen-sulfur doped carbon matrix. After nitrogen and sulfur co-doping, the carbon matrix has better conductivity and increased wettability with the electrolyte, which is conducive to accelerating the migration and diffusion of electrons and ions in the oxygen evolution reaction. At the same time, catalytically active centers such as pyridine nitrogen and pyrrole nitrogen are formed, which promotes the oxygen evolution reaction. In addition, the OER catalyst has a higher specific surface area, exposing more oxygen evolution reaction active sites, thereby having better oxygen evolution reaction catalytic activity.

[0046] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a cobalt-manganese double metal oxide OER catalyst, characterized by, The preparation method is the following steps: step A, adding xylene, polyethylene glycol, 2-thiophenyl naphthalene dicarboxylic acid imide, p-toluene sulfonic acid into a flask equipped with a water trap, stirring after reaction, rotary evaporation, washing, drying, obtaining polyethylene glycol copolymer; Step B, adding water, cobalt salt, manganese salt, polyethylene glycol copolymer into a hydrothermal reactor, stirring, then adding precipitator, carrying out reaction, filtering after cooling, washing, drying, then calcining the product in an electric resistance furnace, cooling, obtaining cobalt-manganese bimetallic oxide OER catalyst; The calcining in step B is first carried out in air atmosphere, 280-300℃ for 2-3h, then carried out in nitrogen atmosphere, 600-700℃ for 1.5-2.5h.

2. The method of claim 1, wherein the cobalt-manganese double metal oxide OER catalyst is prepared by a method comprising: The ratio of polyethylene glycol, 2-thiophenyl naphthalene dicarboxylic acid imide, p-toluene sulfonic acid in step A is 1mol:(1-1.2)mol:(0.002-0.003)mol. ​ 3. The method of making a cobalt-manganese double metal oxide OER catalyst of claim 1, wherein, The reaction in step A is carried out at 110-130℃ for 2-3h.

4. The method of making a cobalt-manganese bimetallic oxide OER catalyst of claim 1, wherein, The ratio of cobalt salt, manganese salt, polyethylene glycol copolymer, precipitator in step B is 2mol:1mol:(300-600)g:(5-8)mol.

5. The method of making a cobalt-manganese double metal oxide OER catalyst according to claim 4, wherein, The cobalt salt is cobalt chloride or cobalt nitrate, and the manganese salt is manganese chloride or manganese nitrate.

6. The method of making a cobalt-manganese bimetallic oxide OER catalyst of claim 4, wherein, The precipitator in step B is urea or hexamethylenetetramine.

7. The method of making a cobalt-manganese double metal oxide OER catalyst of claim 1, wherein, The reaction in step B is carried out at 100-120℃ for 12-18h.

8. The method of making a cobalt-manganese bimetallic oxide OER catalyst of claim 2, wherein, The preparation method of 2-thiophenyl naphthalene dicarboxylic acid imide is: adding N,N-dimethylformamide, 1,4,5,8-naphthalene tetracarboxylic anhydride, 5-aminothiophene-2-methyl carboxylate, triethylamine in a flask equipped with a condensation reflux tube, the ratio is 1mol:(2.2-2.6)mol:(2.5-3)mol, heating to 120-135℃ in nitrogen atmosphere, stirring for 6-12h, diluting the solution with water, filtering, washing the filter cake with acetone, drying the product, adding into methanol, adding potassium hydroxide solution with a concentration of 3.5-4mol / L, heating to 85-95℃, condensation reflux reaction for 4-6h, adding hydrochloric acid solution dropwise after cooling, precipitate is separated out, filtering, washing, drying, obtaining 2-thiophenyl naphthalene dicarboxylic acid imide.

9. Application of cobalt-manganese bimetallic oxide OER catalyst obtained by the preparation method of any one of claims 1-8 in zinc-air battery.

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