Porous nitrogen-doped carbon nanosheet on graphene as metal-free catalyst for oxygen reduction reaction in air-cathode microbial fuel cells

• PNCN was derived from GO–PANI hybrid through carbonization and activation treatment.
• The electrode modified by PNCN exhibits high catalytic activity for ORR.
• Maximum power density of 1159.34 mW/m2 obtained from PNCN-MFC was higher than Pt-MFC.

Porous nitrogen-doped carbon nanosheet on graphene (PNCN) was used as an alternative cathode catalyst for oxygen reduction reaction (ORR) in air-cathode microbial fuel cells (MFCs). Here we report a novel, low-cost, scalable, synthetic method for preparation of PNCN via the carbonization of graphite oxide–polyaniline hybrid (GO–PANI), subsequently followed by KOH activation treatment. Due to its high concentration of nitrogen and high specific surface area, PNCN exhibited an excellent catalytic activity for ORR. As a result, the maximum power density of 1159.34 mW m− 2 obtained with PNCN catalyst was higher than that of Pt/C catalyst (858.49 mW m− 2) in a MFC. Therefore, porous nitrogen-doped carbon nanosheet could be a good alternative to Pt catalyst in MFCs.