Metal–Organic Frameworks-Derived Core/Shell Porous Carbon Materials Interconnected by Reduced Graphene Oxide as Effective Cathode Catalysts for Microbial Fuel Cells

Microbial fuel cells (MFCs) are highly appealing for recovering electricity from organic matter, with the help of electrogenic bacteria. However, the lack of cost-efficient oxygen reduction reaction (ORR) catalysts is the main limitation for the performance of MFCs, and the development of highly electrocatalytic active ORR catalysts for MFCs remains very challenging. Here, core/shell carbon materials doped with Co and N (NC@CoNC) are prepared from bimetallic metal–organic frameworks (MOFs) via a facile pyrolysis method. After being interconnected by reduced graphene oxide (rGO), this unique NC@CoNC/rGO composite exhibits excellent electrocatalytic activity when used as the cathode catalyst in MFCs. The as-fabricated NC@CoNC/rGO catalyst facilitates favorable four-electron ORR, which can be due to the uniform distribution of Co nanoparticles, high N content, large surface area, and conductive graphene framework. Furthermore, the optimized NC@CoNC/rGO achieves a maximum power density of 2350 mW m^–2, which is even higher than that generated with commercial Pt/C (2002 mW m^–2). This work demonstrates that the nonprecious metal catalyst NC@CoNC/rGO can be considered to be an good alternative in MFCs.