A Highly Efficient Catalyst toward Oxygen Reduction Reaction in Neutral Media for Microbial Fuel Cells

A nanocomposite of cobaltosic oxide and nitrogen-doped graphene (Co3O4/N-G) was prepared by the facile hydrothermal method. Morphology characterizations show that the Co3O4 nanoparticles with crystalline spinel structure are uniformly dispersed on the nitrogen-doped graphene nanosheets, and the graphene weight fraction in Co3O4/N-G composite is estimated to be similar to 20%. Meanwhile, electrochemical measurements reveal that the as-prepared Co3O4/N-G nanocomposite exhibits a high catalytic activity and long-term stability in neutral electrolyte. Moreover, the use of Co3O4/N-G as cathode catalyst for oxygen reduction in microbial fuel cells (MFCs) to produce electricity was also investigated. The obtained maximum power density was 1340 +/- 10 mW m(-2), which was as high as almost four times that of the plain cathode (340 +/- 10 mW m(-2)), and only slightly lower than that of a commercial Pt/C catalyst (1470 +/- 10 mW m(-2)). All the results prove that a Co3O4/N-G hybrid can be a good alternative to platinum catalysts for practical MFC applications.