Nitrogen Coordinated Iron on Porous Carbon–Titanium Nitride Hybrid: A Non-precious Metal Catalyst for the 4e– ORR Pathway

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 m2 g–1. 57Fe Mössbauer spectroscopy reveals the presence of FeN4 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% HO2– formation during ORR in alkaline media, outperforming the PtC benchmark catalyst. The efficient ORR performance is attributed to the presence of FeN4 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–N4 active sites for fuel cell and electrolyzer applications.