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Cobalt and nitrogen codoped carbon-based oxygen reduction catalyst of three-dimensional hierarchical porous structure and preparation and application thereof

A hierarchical porous catalyst technology, applied in the field of electrochemistry, can solve the problems of difficult regulation of the pore structure of the catalyst, the decrease of the number of catalyst active sites, nitrogen dissociation, volatilization, etc., and achieve excellent oxygen reduction catalytic activity and electrochemical stability, excellent Mass transfer performance, the effect of excellent mass transfer performance

Active Publication Date: 2016-02-24
BEIJING UNIV OF CHEM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Due to the use of a carbon source with a relatively single pore structure as the carbon carrier in this preparation method, the pore structure of the catalyst is not easy to control; on the other hand, the Me-N x Coordination bond energy is low, and nitrogen dissociation and volatilization are prone to occur at high temperatures, resulting in a decrease in the number of active sites of the prepared catalyst, making it difficult to obtain high catalytic activity

Method used

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  • Cobalt and nitrogen codoped carbon-based oxygen reduction catalyst of three-dimensional hierarchical porous structure and preparation and application thereof
  • Cobalt and nitrogen codoped carbon-based oxygen reduction catalyst of three-dimensional hierarchical porous structure and preparation and application thereof
  • Cobalt and nitrogen codoped carbon-based oxygen reduction catalyst of three-dimensional hierarchical porous structure and preparation and application thereof

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Embodiment 1

[0030] Preparation of Embodiment 1 Hierarchical Porous Carbon

[0031] After the yellow cattle bone is cleaned and crushed into bone powder, it is placed in a tube furnace at a flow rate of 200sccmin -1 Under the protection of high-purity argon, with 5 oC min -1 Warm up to 400 o C carbonization, stop heating after 3 hours of heat preservation, and naturally cool to room temperature to obtain a pre-carbonized product; weigh 5 g of the pre-carbonized product and activator KOH according to a mass ratio of 1:1 and grind and mix evenly, under the protection of argon at 2.5 oC min -1 Warm up to 850 oC , after heat preservation for 1h, naturally cool to room temperature to obtain activated carbonized product; then place the above activated carbonized product in 2MHNO 3 Stir and pickle in the solution for 12h, then wash with deionized water, 110 o After C was dried for 12 hours, hierarchical porous carbon was obtained, and its scanning electron microscope photo is shown in figu...

Embodiment 2

[0035] Using the preparation process of Example 1, the difference is that the amount of hierarchical porous carbon is increased to 0.4 g to prepare the catalyst Co-N-HPC-2. Depend on image 3 Nitrogen adsorption and desorption curve tests show that the catalyst has a high specific surface area, reaching 859.1m 2 g -1 , among which, micropores accounted for 28.7%, mesopores accounted for 65.8%, and macropores accounted for 5.5%. Its catalytic oxygen reduction reaction activity curve is shown in Figure 4 , compared with the Co-N-C catalyst prepared by the common carbon support VulcanXC-72, the catalyst has higher half-wave potential and kinetic current, showing excellent catalytic activity for oxygen reduction; in addition, the catalyst also has a larger Limit diffusion current, excellent mass transfer performance.

Embodiment 3

[0037] The preparation process of Example 1 is adopted, and the difference is that the heat treatment temperature of vitamin B12 and hierarchical porous carbon is reduced to 700 o C prepares the catalyst Co-N-HPC-3, which not only has excellent oxygen reduction catalytic activity, but also exhibits excellent electrochemical stability and methanol poisoning resistance, see Figure 6 , 7.

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Abstract

The invention relates to a cobalt and nitrogen codoped carbon-based oxygen reduction catalyst of a three-dimensional hierarchical porous structure and a preparation method. According to the preparation method, a bovine bone is used as a carbon precursor, in-situ nitrogen doped hierarchical porous carbon prepared through activation and carbonization is used as a carrier, vitamin B12 of a cobalt-nitrogen chelated structure is used as a cobalt and nitrogen precursor, and the cobalt and nitrogen codoped carbon-based catalyst is prepared by pyrolyzing the porous carbon and vitamin B12 under the inert atmosphere at the same time, wherein the content of doped cobalt is 0.005-4%, and the content of doped nitrogen is 0.5-5%. Compared with the prior art, the catalyst is high in oxygen reduction catalytic activity and stability, high in poison resistance and good in mass transfer performance, the preparation method is simple and controllable, the precursors are low in price, and the preparation process is environmentally friendly. The catalyst can be widely applied to the fields of proton exchange membrane fuel cells, metal-air fuel cells and the like.

Description

technical field [0001] The invention belongs to the technical field of electrochemistry, and in particular relates to a cobalt-nitrogen co-doped carbon-based oxygen reduction catalyst with a three-dimensional hierarchical porous structure, its preparation and its application in proton exchange membrane fuel cells and metal-air fuel cells application. Background technique [0002] Oxygen reduction reaction (ORR) is the cathode electrode reaction of proton exchange membrane fuel cells and metal-air batteries. The reaction process has high activation energy and large overpotential. It is necessary to use efficient electrode catalysts to increase the reaction rate, thereby promoting battery performance. . At present, noble metal Pt is the most commonly used catalyst for ORR. However, Pt resources are scarce, expensive, and prone to poisoning and sintering during the reaction process, which seriously restricts the commercial application of proton exchange membrane fuel cells and...

Claims

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Application Information

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IPC IPC(8): B01J27/24H01M4/90
CPCY02E60/50
Inventor 王峰何端鹏窦美玲刘海静李志林刘景军吉静宋夜
Owner BEIJING UNIV OF CHEM TECH
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