Porous hollow carbon tube derived from kapok fibres as efficient metal-free oxygen reduction catalysts

Pyrogenic biomass carbon has been deemed a promising alternative to Pt/C for the oxygen reduction reaction (ORR) owing to its low cost, excellent activity, and eco-friendly properties. Herein, a porous carbon tube material derived from kapok fibres was prepared by combining activation with pyrolysis. Electrochemical measurements demonstrated that the kapok fibre-derived material prepared at 900°C had excellent ORR performance with a half-wave potential −0.14 V (vs. Ag/AgCl) close to that of commercial Pt/C (−0.13 V vs. Ag/AgCl) in 0.1 mol L−1KOH. The prepared material also displayed remarkable methanol tolerance and durability. Furthermore, the maximum power density output of the microbial fuel cell using the prepared material was (801±40) mW m−2, comparable to that of the Pt/C cathode ((778±31) mW m−2). The present work provides a facile way of using economical and renewable biomass to develop a porous structure and high-activity cathode ORR catalyst for fuel cell applications.