Iron–Nitrogen-Doped Dendritic Carbon Nanostructures for an Efficient Oxygen Reduction Reaction

A novel Fe–N-doped carbon with a dendritic structure is analyzed as an electrocatalyst for the oxygen reduction reaction. The synthesis of the material was accomplished through a nanocasting approach using pyrrole as the nitrogen and carbon source, and iron chloride as the iron dopant. The Fe–N–C thus-synthesized consists of small nanoparticles with a diameter of ∼240 nm and a pompom-like morphology. They exhibit a relatively high specific surface area combined with a very accessible porosity and a high nitrogen (∼11 wt %) and iron (∼5 wt %) content. With respect to electrocatalytic activity, in basic electrolyte the Fe–N-doped carbon nanopompoms exhibited high onset (0.94 V) and half-wave potentials (0.82 V), and a large kinetic current density (19 mA cm–2), higher than commercial platinum catalysts. The electrocatalysts were also tested in acid electrolyte, giving an onset potential of 0.75 V and a peroxide yield lower than 10% over a wide range of potentials. Furthermore, the newly developed carbon nanostructures exhibit excellent durability, better than commercially available platinum in both media. The excellent electrocatalytic activity is attributed to a combination of a high specific surface area with very accessible porosity and the presence of numerous active centers (i.e., iron coordinated to nitrogen and nitrogen functional groups).