Co₉S₈ activated N/S co-doped carbon tubes: In situ grown on carbon nanofibers for efficient oxygen reduction

Herein, we report a facile and environment-friendly route for the preparation of Co₉S₈ activated N/S co-doped carbon tubes (denoted as Co₉S₈@N/S-CT) in situ grown on a carbon nanofiber network derived from bacterial cellulose. The as-prepared Co₉S₈@N/S-CT has a novel microstructure with homogeneous and lotus root-like carbon tubes plugged with Co₉S₈ active substance, which are embedded in the carbon nanofibers. This nonprecious Co₉S₈@N/S-CT composite has a comparable catalytic activity for the oxygen reduction reaction and superior stability compared with commercial Pt/C catalyst. This is attributed to a synergistic catalytic effect due the intimate contact between Co₉S₈ active sites and the highly conductive heteroatom doped carbon tubes, showing the great potential for using the Co₉S₈@N/S-CT composite as a novel non-precious cathode catalyst in fuel cells or metal-air battery applications.