Nitrogen-doped carbon nanotubes/reduced graphene oxide nanosheet hybrids towards enhanced cathodic oxygen reduction and power generation of microbial fuel cells

A microbial fuel cell (MFC) is a bio-electrochemical device that convert the chemical energy to electrical energy by the oxidation of microorganisms at bioanode, while its powder generation is largely depending on the activity and durability of cathode catalysts. In this work, we report the design and synthesis of N-doped carbon nanotubes/reduced graphene oxide (rGO) nanosheet hybrids with mixed-dimensional characteristics as high-performance oxygen reduction reaction catalyst for cost-saving MFCs. Co-glycolate nanoparticles uniformly coated on rGO nanosheets are reduced to Co nanoparticles, acting as catalysts for the catalyst mediated growth of carbon nanotubes with abundant metal-nitrogen-carbon active sites. The half-wave potential of hybrid electrocatalyst are 0.859 V (vs RHE), comparable to that of benchmark Pt/C. A maximum power density of 1329 mW cm(-2), 1.37 times higher than that of commercial Pt/C catalyst, is achieved in single-chamber MFCs using optimized hybrid electrocatalysts.