Novel carbon-supported Fe-N electrocatalysts synthesized through heat treatment of iron tripyridyl triazine complexes for the PEM fuel cell oxygen reduction reaction

Abstract

2,4,6-Tris(2-pyridyl)-1,3,5-triazine (TPTZ) was used as a ligand to prepare iron-TPTZ (Fe-TPTZ) complexes for the development of a new oxygen reduction reaction (ORR) catalyst. The prepared Fe-TPTZ complexes were then heat-treated at temperatures ranging from 400 °C to 1100 °C to obtain carbon-supported Fe-N catalysts (Fe-N/C). These catalysts were characterized in terms of catalyst composition, structure, and morphology by several instrumental methods such as energy dispersive X-ray, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. With respect to the ORR activity, the Fe-N/C catalysts were also evaluated by cyclic voltammetry, as well as rotating disk and ring-disk electrodes. The results showed that among the heat-treated catalysts, that obtained at a heat-treatment temperature of 800 °C is the most active ORR catalyst. The overall electron transfer number for the catalyzed ORR was determined to be between 3.5 and 3.8, with 10–30% H 2 O 2 production. The ORR catalytic activity of this catalyst was also tested in a hydrogen–air proton exchange membrane (PEM) fuel cell. At a cell voltage of 0.30 V, this fuel cell can give a current density of 0.23 A cm −2 with a maximum MEA power density of 0.070 W cm −2 indicating that this catalyst has potential to be used as a non-noble catalyst in PEM fuel cells.