Caffeine derived graphene-wrapped FeC nanoparticles entrapped in hierarchically porous FeNC nanosheets for boosting oxygen reduction reaction.

It is a vital requirement to explore high-efficiency and stable electrocatalysts for oxygen reduction reaction (ORR) to further relieve energy depletion. However, it is a critical challenge to develop low cost and high-quality carbon-based catalysts. Herein, a caffeine chelation-triggered pyrolysis approach was developed to construct graphene-wrapped FeC nanoparticles incorporated in hierarchically porous FeNC nanosheets (G-FeC/FeNC). The present Fe salt and its content as well as the pyrolysis temperature were carefully investigated in the control groups. The G-FeC/FeNC catalyst showed a more positive onset potential (E = 1.09 V) and half-wave potential (E = 0.88 V) in a 0.1 M KOH solution, which outperformed commercial Pt/C (E = 0.83 V, E = 0.95 V), showing the excellent catalytic performance for the ORR activity, coupled with remarkable stability (only 0.18 mV negative shift in E after 2000 cycles). This work provides some valuable insights for developing advanced electrocatalysts for energy storage and conversion related research.