Nitrogen Coordinated Iron on Porous Carbon–Titanium Nitride Hybrid: A Non-precious Metal Catalyst for the 4e<sup>–</sup> ORR Pathway
Iosif Tantis, Nikolaos Chalmpes, Mihail R. Krumov, Qihao Li, Héctor D. Abruña, Alexios P. Douvalis, Emmanuel P. Giannelis
Abstract
A nitrogen coordinated iron (Fe–N) on porous carbon/carbon nitride support decorated with titanium nitride nanoparticles, Fe–N–C/TiN, was prepared by a simple and scalable method and evaluated as a non-precious metal group oxygen reduction reaction (ORR) electrocatalyst for anion-exchange membrane fuel cells. The samples synthesized by a one-pot reaction followed annealing at 750 °C contain Fe–N–C sites on porous carbon/carbon nitride decorated with TiN nanoparticles and exhibit a high surface area of 620 m 2 g –1 . 57 Fe Mössbauer spectroscopy reveals the presence of FeN 4 active centers, whose formation is facilitated only by the presence of TiN nanoparticles. ORR testing shows a half-wave potential of 0.89 V with a limiting current of 5.5 mA cm –2 following the 4-electron pathway to water with only 5% HO 2– formation during ORR in alkaline media, outperforming the PtC benchmark catalyst. The efficient ORR performance is attributed to the presence of FeN 4 active sites and the high specific surface area of the support. Moreover, the material exhibited stable electrochemical performance during 10,000 ORR cycles. This straightforward and scalable approach offers a pathway to synthesize next-generation, high performance non-precious metal-based electrocatalysts with accessible Fe–N 4 active sites for fuel cell and electrolyzer applications.