Catalytic material for oxygen reduction and with gradient pore structure and preparation method thereof

Abstract

The invention discloses a catalytic material for oxygen reduction and with a gradient pore structure and a preparation method thereof. The preparation method comprises the following steps: dissolving zinc nitrate hexahydrate in deionized water; adding an aqueous zinc nitrate hexahydrate solution into an aqueous solution containing 2-methylimidazole, iron phthalocyanine and a silicon dioxide template, and carrying out stirring; performing centrifuging, washing and drying to prepare a gray precursor sample; and carrying out heat treatment on the precursor in an inert atmosphere and removing a template by using hydrofluoric acid to obtain the catalytic material for oxygen reduction and with the gradient pore structure. According to the catalytic material for oxygen reduction, an iron source and a silicon dioxide template are introduced on the basis of a microporous ZIF-8 derivative material with a high specific surface area; the material has a large number of iron-nitrogen active sites, low-boiling-point zinc volatilizes in a carbonization process to generate a large number of micropores, and the gradient porous structure is constructed by adding mesopores and macropores brought by the silicon dioxide template, so the mass transfer rate of an electrochemical reaction is improved; and the material shows excellent oxygen reduction performance in both alkaline and acidic media, and can be applied to various chemical power supply devices as an oxygen reduction catalyst.

Description

technical field [0001] The invention belongs to the field of new energy materials, and in particular relates to an oxygen reduction catalytic material with a gradient pore structure and a preparation method thereof. Background technique [0002] Green chemical power sources such as high-efficiency fuel cells and metal-air batteries have been developed rapidly in the past decade, and they have achieved commercial applications in some fields, and are getting closer to the goal of large-scale commercialization. In addition to the need to improve the output performance of the battery, the high production cost is also one of the important reasons that limit its commercialization. The oxygen reduction reaction occurs on the cathode side of the above-mentioned green chemical power sources to ensure the operation of the battery, but the oxygen reduction reaction with slow kinetics usually requires the use of noble metal catalytic materials to accelerate the electrochemical reaction....

AI Technical Summary

Problems solved by technology

Although this patent application realizes the aqueous phase synthesis of ZIF, the method introduces amines as additives in the preparation process, which increases the preparation cost of the material to a certain extent.

And, when generating solid-state intermediates, a large amount of 2-methylimidazole is added, and the product morphology of the intermediates is difficult to control, and basically there is no regular morphology

[0005] In addition, most metal-organic framework-derived catalytic materials have a high specific surface area, but their pore size distribution is generally concentrated below 5nm, and the lack of large-sized mesopores and macropores will limit the catalytic materials in the process of oxygen reduction reaction. Material transfer efficiency, especially the high mass transfer requirements of batteries at high current densities

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