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Updated: Aug 3, 2025

Synthesis of Platinum-nickel Nanowires and Optimization for Oxygen Reduction Performance
Published on: April 27, 2018
Potential-Dependent Active Moiety of Fe-N-C Catalysts for the Oxygen Reduction Reaction
Kang Liu1,2, Junwei Fu2, Tao Luo2
1School of Metallurgy and Environment, Central South University, Changsha, Hunan 410083, P. R. China.
Abstract:
The real active moiety of Fe-N-C single-atom catalysts (SACs) during the oxygen reduction reaction (ORR) depends on the applied potential. Here, we examine the ORR activity of various SAC active moieties (Fe-N4, Fe-(OH)N4, Fe-(O2)N4, and Fe-(OH2)N4) over a wide potential window ranging from -0.8 to 1.0 V (vs. SHE) using constant potential density functional theory calculations. We show that the ORR activity of the Fe-N4 moiety is hindered by the slow *OH protonation, while the Fe-(OH2)N4 (0.4 V ≤ U ≤ 1.0 V), *O2-assisted Fe-N4 (-0.6 V ≤ U ≤ 0.2 V), and Fe-(OH)N4 (U = -0.8 V) moieties dominate the ORR activity of the Fe-N-C catalysts at different potential windows. These oxygenated species modified the single-atom Fe sites and can promote *OH protonation by regulating the electron occupancy of the Fe 3d (spin-up) and Fe 3d (spin-down) orbitals. Overall, our findings provide guidance for understanding the active moieties of SACs.
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