Novel porous nitrogen doped graphene/carbon black composites as efficient oxygen reduction reaction electrocatalyst for power generation in microbial fuel cell

Abstract

To improve the power generation of a microbial fuel cell (MFC), a porous nitrogen-doped graphene/carbon black (NG/CB) composite as efficient oxygen reduction reaction (ORR) electrocatalyst was successfully synthesized by pyrolyzing graphene oxide (GO) encapsulated CB with cetyltrimethyl ammonium bromide as a bridge. This concept-to-proof synthesis can be considered as a template-like method. Based on this method, one composite named as NG/CB-10 was acquired using the optimized GO-to-CB mass ratio of 10:1. Electrochemical tests demonstrate that NG/CB-10 can catalyze ORR in neutral-pH medium through a four-electron pathway with positively shifted the onset potential, the enhanced current density and reduced charge transfer resistance. CB addition also prolongs the stability of NG/CB-10. The enhancement in electrochemical performance of NG/CB-10 was attributed to the enlarged surface area, abundant mesopores and high content of pyridinic nitrogen. The maximum power density of MFC equipping NG/CB-10 as cathode electrocatalyst reached 936 mW·m-2, which was 26% higher than that of NG and equal to that of platinum/carbon. The cost of NG/CB-10 was reduced by 25% compared with that of NG. This work provides a novel method to synthesize promising ORR electrocatalyst for MFC in the future.