Atomically dispersed dual Fe centers on nitrogen-doped bamboo-like carbon nanotubes for efficient oxygen reduction

Interfacial atomic configuration between dual-metal active species and nitrogen-carbon substrates is of great importance for improving the intrinsic activity of catalysts toward oxygen reduction reaction (ORR). Thus, from the atomic-scale engineering we develop a high intrinsic activity ORR catalyst in terms of incorporating atomically dispersed dual Fe centers (single Fe atoms and ultra-small Fe atomic clusters) into bamboo-like N-doped carbon nanotubes. Benefiting from atomically dispersed dual-Fe centers on the atomic interface of Fe-N_x/carbon nanotubes, the fabricated dual Fe centers catalyst exhibits an extremely high ORR activity (E_onset = 1.006 V; E_1/2 = 0.90 V), beyond state-of-the-art Pt/C. Remarkably, this catalyst also shows a superior kinetic current density of 19.690 mA·cm⁻², which is 7 times that of state-of-the-art Pt/C. Additionally, based on the excellent catalyst, the primary Zn-air battery reveals a high power density up to 137 mW·cm⁻² and sufficient potential cycling stability (at least 25 h). Undoubtedly, given the unique structure–activity relationship of dual-Fe active species and metal-nitrogen-carbon substrates, the catalyst will show great prospects in highly efficient electrochemical energy conversion devices.