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Three-dimensional nitrogen-doped graphene with hierarchical channels prepared from polybenzimidazole

A nitrogen-doped graphene and pore technology, which is applied in the manufacture of hybrid/electric double-layer capacitors, catalysts for physical/chemical processes, structural parts, etc., can solve problems such as inability to mix templates, reduced catalytic performance, and reduced active sites.

Inactive Publication Date: 2019-04-02
SHANDONG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Two-dimensional graphene is prone to layer-layer stacking, and the graphite structure loses the characteristics of graphene
Two-dimensional nitrogen-doped graphene is easy to stack or aggregate to reduce the active sites, and the catalytic performance is reduced due to the lack of mass transfer channels.
Compared with the preparation of nitrogen-doped graphene by materials such as polyaniline and polypyrrole, mPBI and oPBI are soluble and easy to coat on the surface of the template, while polyaniline and polypyrrole are insoluble and cannot be mixed with the template

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] [Example 1] Preparation of mPBI: Add polyphosphoric acid (PPA) (100 g) into a three-necked flask equipped with electric stirring and nitrogen protection, and stir at 160° C. for 1 h under nitrogen protection to remove excess water and air. DABz (4g, 18.7mmol) and isophthalic acid (3.1g, 18.7mmol) were mixed evenly, and slowly added into a three-necked flask. The nitrogen flow rate was controlled to prevent DABz from being oxidized, and at the same time, the reaction temperature was raised to 200° C., and the reaction was continued for 5-8 hours with insulation and stirring. With the increase of reaction time, the polymerization system gradually became viscous. Stop the reaction when the viscosity is appropriate, slowly transfer the reaction mixture to a large amount of deionized water, spin, wash, dry, pulverize, and wash with deionized water several times to remove polyphosphoric acid and unreacted reactants to obtain mPBI. The molecular weight of mPBI was determined ...

Embodiment 2

[0018] [Example 2] Synthesis of oPBI: Add polyphosphoric acid (PPA) (100 g) into a three-necked flask equipped with electric stirring and nitrogen protection, and stir at 160° C. for 2 hours under nitrogen protection to exclude air and moisture. DABz (4g, 18.7mmol) and 4,4'-diphenyl ether dicarboxylic acid (4.83g, 18.7mmol) were mixed evenly, and slowly added into a three-necked flask. Control the nitrogen flow rate to prevent DABz from being oxidized, and at the same time raise the reaction temperature to 200°C and continue to keep warm and stir for 5~8h. With the increase of reaction time, the polymerization system gradually became viscous. Stop the reaction when the viscosity is right, and slowly transfer the reaction mixture to a large amount of deionized water to spin, wash, dry, pulverize, and wash with deionized water several times to remove polyphosphoric acid and unreacted reactants to obtain oPBI. The molecular weight of oPBI was determined with an Ubbelohde viscome...

Embodiment 3

[0019] [Example 3] Use calcium carbonate particles with a particle size of 30nm as a template to mix with mPBI, and the mass ratio of mPBI to nanoscale calcium carbonate template is 1:1 as an example:

[0020] In a 250mL beaker, add 1g of mPBI (viscosity-average molecular weight: 30,000 to 50,000) and 20mL of DMAc, heat and stir to dissolve it, and slowly add 1g of calcium carbonate with a particle size of 30nm to disperse evenly while stirring. The obtained viscous liquid is heated and concentrated to nearly dryness under stirring, and dried in a vacuum oven at 100°C. The solid is ground in a mortar, transferred to a porcelain boat, and kept in a high-temperature electric furnace at 900°C under the protection of argon. Pyrolyze under heat, keep warm for 2-3h, wait for the furnace temperature to drop to room temperature, take it out, grind it finely to obtain a black powdery solid, transfer it to a 250mL Erlenmeyer flask, add 70mL of 3mol / L hydrochloric acid, heat, stir for 8h,...

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PUM

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Abstract

The invention is a method for preparing three-dimensional nitrogen-doped graphene with multi-level channels. Use mPBI or oPBI in polybenzimidazole (PBI) as the carbon source and nitrogen source, and use nano-calcium carbonate as the template agent. PBI is dissolved and mixed with the nano-template agent. Under the protection of inert gas, it is pyrolyzed, and the calcium carbonate is decomposed to produce small Pores, large pores are formed after the template is removed, and the three-dimensional nitrogen-doped graphene with multi-level channels interconnected by the large pores and small pores, and the inter-connected multi-level channels have the effect of enhancing mass transfer. PBI uses soluble polymers with a viscosity-average molecular weight of 3-50,000; calcium carbonate particle size of 10-100nm; PBI: calcium carbonate = 2:1-1:4; pyrolysis temperature of 800-1100°C; dilute hydrochloric acid removal Templating agent. The prepared three-dimensional nitrogen-doped graphene with multi-level pores can be used in the fields of oxygen reduction catalysts for fuel cells or metal-air battery cathodes, oxygen evolution catalysts for electrolyzed water anodes, and electrode materials for supercapacitors.

Description

technical field [0001] It belongs to the field of nanomaterial preparation and is used in the fields of fuel cells, metal-air battery cathode catalysts, electrolytic water catalysts, lithium-ion battery materials, supercapacitor electrode materials and electrochemical sensors in the clean energy field. . Background technique [0002] Graphene's unique properties and excellent physical and chemical properties have aroused people's research interest. Because two-dimensional graphene is prone to layer-layer stacking, the graphite structure loses the characteristics of graphene. For this reason, people began to study three-dimensional graphene (ChenK, et al. J Mater Chem (Journal of Chemical Materials), 2012, 22: 20968). The three-dimensional graphene material not only has the inherent physical and chemical properties of graphene sheets, but also has excellent characteristics such as large specific surface area, good electronic conductivity and enhanced mass transfer due to it...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01J31/02C25B11/06C25B1/04H01G11/44H01G11/86H01M4/88H01M4/96
CPCB01J31/0244B01J2231/60B01J2231/70C25B1/04C25B11/095H01G11/44H01G11/86H01M4/88H01M4/96Y02E60/13Y02E60/36Y02E60/50
Inventor 李忠芳吕亚楠王素文
Owner SHANDONG UNIV OF TECH