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 FeCl 3 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 (−0.08 V compared to −0.12 V and −0.15 V), 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 25 mV negative than that for Pt/C (−0.08 V to −0.055 V) and the ORR current density at merely −0.3 V for STS800 (−2.16 mA cm −2 ) is larger than that for Pt/C (−2.12 mA cm −2 ), which indicates its superior ORR activity even compared to Pt/C. Besides, the current for STS800 retains 95% at −0.2 V in 30000 s while that for Pt/C just retains 88%, which reveals its longer durability. With the addition of 3 M 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.