A recyclable preparation method of microporous iron-nitrogen doped carbon catalyst material

Abstract

The invention belongs to the technical field of energy conversion and storage materials, and provides a recyclable preparation method of a microporous iron-nitrogen doped carbon catalyst material. Specifically, it is a liquid-phase in-situ recyclable method for preparing nitrogen-containing polymer precursors adsorbed by iron ions, wherein the yield of nitrogen-containing polymers is as high as 98%, and Fe obtained by solid-liquid separation ions / N-Polymer does not require washing treatment, and directly through molten salt outsourcing, annealing and microporous treatment, the iron-nitrogen-doped carbon material with electrocatalytic oxygen reduction performance is better than commercial Pt / C catalyst. The filtrate after solid-liquid separation contains very little unpolymerized monomers, and the ferrous ions in the filtrate can be re-oxidized to ferric ions by hydrogen peroxide for Fe ions The cyclic preparation of / N-Polymer has no waste liquid discharge, and the iron-nitrogen-doped carbon material prepared by the cycle has the same electrocatalytic oxygen reduction catalytic performance as the iron-nitrogen-doped carbon material synthesized for the first time. The method of the invention has mild experimental conditions, simple method, good repeatability, economy and environmental protection.

Description

Technical field [0001] The present invention belongs to the field of energy conversion and storage material, and more particularly to a recyclacy preparation method of microporous iron-nitrogen-doped carbon catalyst material. Background technique [0002] With the increasing consumption of fossil energy, the global energy crisis and environmental deterioration have continued to upgrade. As the largest developing country in the world, China has developed rapidly in the reform and opening up, and environmental pollution issues such as water, soil, air brought. Dual pressures from energy and environments drive people constantly seek new green energy and efficient energy storage and transformation technology. In many energy storage and conversion types, electrochemical energy such as metal-air batteries, fuel cells, etc. have been recognized as the most developable energy conversion and storage due to their ability to have an environmentally friendly, high security, high energy densi...

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Problems solved by technology

At present, the preparation methods of iron-nitrogen-doped carbon material precursors mainly include the following categories. The first category is to directly mix the iron source and nitrogen source and then anneal after drying. This method is simple, but the prepared materials are often large in size , the specific surface area is low, and the micro-mesopores are rare, resulting in lower catalytic activity for oxygen reduction in alkaline solution than commercial Pt-based catalysts (Angew.Chem.Int.Ed.2014,53,1.); The second type of method is an improvement of the first type of method. Since the materials obtained by the first type of method have limitations in specific surface area and pore structure, it is possible to add hard templates such as porous silicon and silicon nanospheres during the preparation of the precursor. (J.Am.Chem.Soc.2013,135,16002.), etch it after annealing, although this method can improve the porosity and oxygen reduction catalytic performance of the material, but the hard template preparation and subsequent The etching process is time-consuming, which is not conducive to large-scale production; the third category is to use carbon-based materials with large specific surface areas such as carbon nanotubes, graphene, and carbon nanospheres as substrates (Science 2011, 332, 443.; ACS Catal.2014, 4,3928.), coated with iron source and nitrogen source on its surface, or directly synthesized nitrogen-containing polymer with nanostructure and mixed with iron source, and then annealed at high temperature to obtain iron-nitrogen doped with high specific surface area Carbon materials show higher oxygen reduction catalytic performance than Pt-based catalysts in alkaline solutions. Although this method can save the template process, the preparation of the matrix, surface coating or synthesis of nanomaterials also increases the production process. The complexity is not conducive to cost reduction and mass production; the fourth category is to prepare metal-organic frameworks (MOFs) with uniform size and morphology, and obtain microporous iron-nitrogen, cobalt-nitrogen single-atom clusters by annealing Doped carbon materials (J.Am.Chem.Soc.2017,139,8078.; Adv.Mater.2018,1706758.), this kind of material has very high oxygen reduction catalytic performance, is the current metal-nitrogen doped carbon The research hotspot of materials, but from the perspective of industrialization, the preparation cost of metal-organic framework compounds is high, and the yield is low, which is not conducive to large-scale synthesis

[0004] Therefore, how to prepare precursors containing iron and nitrogen sources through a simple synthesis method, and obtain low-cost, high-performance iron-nitrogen-doped carbon catalysts through simple microporosity treatment is still a challenge; at the same time, The process of preparing precursors by wet chemical methods usually produces a large amount of industrial wastewater, and wastewater treatment will undoubtedly increase production costs. How to recycle the waste liquid of precursors prepared by wet chemical methods and maintain the performance stability of materials prepared in different batches , which is also another challenge faced by large-scale production of materials

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