Doped carbon aerogels as Fe-N-C catalyst in high temperature polymer electrolyte membrane fuel cell

Abstract

A fuel cell uses the chemical energy of hydrogen or other fuels to cleanly and efficiently produce electricity. Fuel cells are unique in terms of the variety of their potential applications providing power for multiple sectors. Hydrogen fuel cells emit only water, addressing critical climate challenges as there are no carbon dioxide emissions. In polymer electrolyte membrane fuel cells, platinum is used as a catalyst to promote the sluggish oxygen reduction reaction. A suitable alternative to critical raw materials are iron-nitrogen complexes embedded in a porous, carbonaceous structure. Carbon aerogels have a great potential to be used as a carbon host for this purpose. Carbon aerogels are three-dimensional, open porous solid materials produced via carbonization of organic aerogels based on e.g. resorcinol-formaldehyde polymers. Carbon aerogels exhibit unique properties such as well-controlled pore size distribution, high porosity, large specific surface area, high electrical conductivity and low envelope density. These characteristics make them promising materials for applications in adsorption, catalysis, supercapacitors, fuel cells or batteries. For the application as a catalyst, the carbon matrix has to be modified in order to get active sites into the carbon structure. Therefore, the carbon aerogel is treated with different synthesis steps to introduce nitrogen and iron into the carbon structure [2]. Prior nitrogen doping of the carbon aerogel, oxygen doping was identified as a crucial step. The oxidized carbon aerogel can then be mixed with nitrogen and iron precursors and thermally treated to get Fe-N-C materials. Within this poster presentation, we will report on our recent studies showing different synthesis techniques and physical, chemical and electrochemical characterization of doped carbon aerogels. For this purpose, the microstructure of the doped carbon aerogels is investigated with physisorption measurements and scanning and transmission electron microscopy. In addition, measurement of the electrical conductivity using the four-pin method and Raman spectroscopy are carried out. Finally, the electrochemical activity is investigated with the rotating ring-disk electrode.