Study On Preparation Of Covalent Organic Polymer-based Oxygen Reduction Catalyst And Its Fuel Cell Application

The problem of energy has gradually attracted people’s attention,With the continuous development of economy and the social.However,the reserves of traditional energy such as oil and coal are limited,and the massive use of traditional fossil energy has caused serious environment problems.Therefore,the search for sustainable green energy is of irreplaceable significance in promoting social and economic development.In recent years,the fuel cell with excellent energy conversion efficiency and low pollution has attracted continuous attention from all aspects of society.However,most commercial fuel cells currently used in the market use Pt/C as the cathode oxygen reduction catalyst,and the high cost of Pt/C limits its large-scale promotion.Therefore,the key factor to promote the popularization of fuel cell is to find a new cathode catalyst with low cost and high efficiency.At the same time,the design of the oxygen reduction catalyst at the present stage is mostly based on the semi-battery test,ignoring the effect of mass transfer,which leads to problems such as flood.In this paper,based on the advantages of easy doping and easy regulation of pore structure of covalent organic polymer,an efficient and stable cathodic oxygen reduction catalyst with covalent organic polymer as the precursor was synthesized by a simple method.Combined with the RDE and the PEMFC test,it was found that the suitable mesoporous and macropore could effectively promote the performance of PEMFC by improving the mass transfer,which solved the problem of poor mass transfer in the use of fuel cell catalysts and provided an idea for the design of a more practical fuel cell oxygen reduction catalyst.The specific research contents are as follows:1.The covalent organic polymer cop-pd of the nitrogen-rich precursor was synthesized from 2,6-Dichloropurine and Piperazine by simple hydrothermal method,and the multistage porous single atom catalyst was obtained after carbonization at high temperature.By means of electron microscopy,X-ray photoelectron spectroscopy and synchrotron radiation analysis,MSA formed an obvious graded pore structure on the basis of COP-PD,and at the same time formed a Fe-Nn active site with single atom distribution.Among them,the initial potential of MSA/200Fe-3Zn reached 0.944 V and the half-wave potential reached 0.813 V in 0.5M H2SO4 solution.It also shows good stability and resistance to methanol poisoning.This work provides a design scheme for a highly efficient acid oxygen reduction catalyst.2.The influence of pore structure on catalytic performance was investigated.Catalysts with different pore sizes were prepared by adding different contents of Zn as high temperature pore forming materials.The relationship between pore structure and electrochemical activity area was studied.It was found that the electrochemical active area of the catalyst MSA/200Fe-bZn was similar to the sum of its mesoporous macropore area,and its electrochemical performance proves that the mass transfer of fuel cells can be effectively solved by adjusting the mesoporous macroporous structure,thus improving their performance.3.Based on the abundant pore structure and good stability of covalent organic polymer,in this paper,the polymerization of 2,6-diaminopyridine was realized by microwave using water as a solvent,and the catalyst P-2,6-DP50 was prepared.It showed excellent oxygen reduction reaction(ORR)performance under alkaline conditions,the initial potential at 1.01 V and half wave potential 0.888 V.At the same time,it performs well in the stability and anti-methanol toxicity tests.This work provides an idea for the design of efficient alkaline oxygen reduction catalysts.