Biomass-derived hierarchical honeycomb-like porous carbon tube catalyst for the metal-free oxygen reduction reaction

Biomass carbon materials have been deemed a promising metal-free catalyst for the oxygen reduction reaction (ORR) owing to their renewable, high electrical conductivity and large surface area. However, the required ion transfer process is hampered by an inappropriate porous structure. In this work, a nitrogen-doped honeycomb-like carbon tube with porous structure was synthesized by the pyrolysis of dandelion seed. The results showed that the material prepared at 900°C (HHPT-900) possessed abundant pores of different sizes, which could provide more active sites and ion channels than other biomass carbon materials investigated so far. In addition, the onset potential of HHPT-900 was 0.83V vs. reversible hydrogen electrode (RHE), close to that of commercial Pt/C (0.85V vs. RHE) in 0.1molL−1 KOH. HHPT-900 also proved to be highly methanol tolerant and durable. Furthermore, a higher power density (975±46mWm−2) was obtained when using HHPT-900 as a cathode catalyst in a microbial fuel cell than that of the Pt/C cathode (823±41mWm−2). The present work provides an easy way to develop a hierarchical honeycomb-like porous carbon tube material that could be used as an effective metal-free ORR catalyst.