Preparation Of Iron-Nitrogen-doped Carbon-based Materials And Study On Their Electrocatalytic Oxygen Reduction Performance

Fuel cell?FC?is an ideal energy conversion technology because of its clean,high efficiency and pollution-free technology.However,its cathode oxygen reduction reaction?ORR?kinetics process is slow,generally requiring the use of rare and expensive platinum catalysts,which leads to high cost of fuel cells and thus hindered its commercialization.In recent years,non-precious metal catalysts for replacing platinum have shown great potential in the field of electrocatalytic ORR.Nevertheless,the preparation processes of non-noble metal catalysts in most cases are complicated,time-consuming,and environmental unfriendly.More seriously,the activity and stability of these catalysts are poor,and the commercial standard cannot be achieved.Therefore,the preparation of non-precious metal catalysts with good catalytic activity and stability by simple methods is highly important from both theoretical and practical aspects.Based on the abundant iron and carbon sources,this thesis explores the simple synthesis of iron-nitrogen-doped carbon materials with high activity and good stability.The electrocatalytic activity and stability of ORR can be further enhanced by surface modification of ionic liquids.This work provides important experimental and theoretical support for future study of non-precious metal ORR catalysis and fuel cell applications.We first prepared a porous carbon material with a pore diameter of 10 nm by neutralization reaction of sulfuric acid and p-phenylenediamine to form protic salt[pPDA][2HSO₄]with following one-step high-temperature carbonization.The presence of large number of oxygen-containing groups renders the obtained carbon hydrophilic properties.After further mixed with ferrous sulfate heptahydrate and carbonized at high temperature,iron-nitrogen-doped carbon catalyst were obtained with their structure and ORR performance carefully characterized.The half-wave potential was 0.836 V vs RHE,21 mV more positive compared to that of commercial Pt/C electrocatalyst.Using the concept of nanoconfinement,we further prepared atomically dispersed Fe-N-C catalyst by first confining ionic liquid[BMIm]FeCl₄ into the cave of zeolitic imidazole framework material?ZIF-8?and then carbonizing the obtained composite material.The surface of the obtained electrocatalyst was further modified using ionic liquid[BMIm][NTf₂],resulting in significantly improved performance.The half-wave potential of the ionic liquid-modified catalyst reached 0.848 V vs RHE,which was 21and 33 mV more positive than that without ionic liquid modification and Pt/C,respectively.