Confined pyrolysis synthesis of N-doped carbon-supported FePr nanoparticles for efficient oxygen reduction based on 3d–4 f orbital coupling

To meet the growing demand for new energy storage and conversion technologies, there is an urgent need to prepare highly efficient, economical and durable oxygen reduction catalysts that can replace those based on precious. Herein, N-doped porous carbon supported FePr nanoparticles (FePr/NC) from MOFs were prepared by confined adsorption and pyrolysis. The characterizations and electrocatalytic properties of the FePr/NC were investigated in details. The prepared FePr/NC catalyst showed excellent ORR catalytic performance with a half-wave potential (E_1/2) of only 0.87 V in a 0.1 M KOH solution, outperforming commercial Pt/C catalyst (E_1/2 = 0.82 V) under the identical conditions. Besides, its onset potential (E_onset) was up to 1.002 V), exceeding the Pt/C (E_onset = 0.92 V. Moreover, the E_1/2 only exhibited a negative shift of 7 mV after 2000 cycles, reflecting its significant stability. To understand their exceptional preference for the ORR, the electronic structure of Fe influenced by the doped Pr and the synergistic effect of the FePr nanoparticles with N-doped carbon were investigated. The coupling of Fe's 3d orbitals with Pr's 4 f orbitals in FePr significantly enhanced the electrocatalytic activity. This work provides a promising strategy for preparation of high-quality transition metal-based carbon catalysts for green energy devices.