Nitrogen-doped carbon with a high degree of graphitization derived from biomass as high-performance electrocatalyst for oxygen reduction reaction

Abstract

It is of great interest to develop metal-free electrocatalysts derived from cheap and environmental friendly biomass for oxygen reduction reaction (ORR). Here we report a facile method to prepare graphene-like N-doped carbons with a high degree of graphitization and large surface area using chitosan as precursor and FeCl3 as soft template. The graphitization degree, surface area and the N species can be simply adjusted by controlling the annealing temperature. The soft template induced sample annealed at 800°C (STS800) exhibits more positive onset potential than the samples annealed at 600°C and 1000°C (−0.08V compared to −0.12V and −0.15V), which demonstrates that all of the high degree of graphitization, large surface area and the high percentages of pyridinic-N and graphitic-N play curial roles in the good ORR activity. The value of onset potential for STS800 is just 25mV negative than that for Pt/C (−0.08V to −0.055V) and the ORR current density at merely −0.3V for STS800 (−2.16mAcm−2) is larger than that for Pt/C (−2.12mAcm−2), which indicates its superior ORR activity even compared to Pt/C. Besides, the current for STS800 retains 95% at −0.2V in 30000s while that for Pt/C just retains 88%, which reveals its longer durability. With the addition of 3M methanol, the CV curve of STS800 shows no noticeable current attenuation, indicating its good methanol tolerance. The excellent ORR activity, good methanol tolerance, and long durability demonstrate that STS800 could be a promising alternative for costly Pt-based electrocatalysts.