Bionic Fe-N-C catalyst with abundant exposed Fe-Nx sites and enhanced mass transfer properties for efficient oxygen reduction.

Transition metal and nitrogen co-doped carbon electrocatalysts are promising candidates to replace the precious metal platinum (Pt) in oxygen reduction reactions (ORR). Unfortunately, the electrochemical performance of existing electrocatalysts is restricted due to limited accessibility of active sites. Inspired by jellyfish tentacles, we design an efficient ORR micro-reactor called Fe-Nx/HC@NWs. It features abundant exposed Fe-Nx active sites dispersed on nitrogen-doped cubic carbon cages, which have a hierarchically porous and hairy structure. The accessible, atomically dispersed Fe-Nx sites and the elaborate substrate architecture synergize to provide the catalyst withremarkable ORR catalytic activity, extraordinary long-term stability, and favorable methanol tolerance in an alkaline electrolyte; overall, its performance is comparable to that of commercial carbon-supported Pt. Our synthesis is facile and controllable, paving a new avenue toward advanced non-precious metal-based electrocatalysts for energy storage and conversion.