Graphene oxide-supported zinc cobalt oxides as effective cathode catalysts for microbial fuel cell: High catalytic activity and inhibition of biofilm formation

Abstract

Microbial fuel cell (MFC) is a unique energy technology that can treat wastewater and concurrently generate electricity. However, the MFC performance is typically rather limited due to the sluggish kinetics of oxygen reduction reaction (ORR) and insufficient ion transfer on the cathode. Thus, development of high-performance ORR catalysts with enhanced ion transfer is of fundamental significance for the wide-spread application of MFC. In this study, nanocomposites (GO-Zn/Co) based on graphene oxide-supported cobalt and zinc oxide nanoparticles were synthesized by a hydrothermal treatment of graphene oxide and cobalt and zinc acetates followed by pyrolysis at controlled temperatures. The porosity of the resulting nanocomposites was found to vary with the pyrolysis temperature and Zn/Co mole ratios. The sample prepared at 800 °C with a Zn/Co mole ratio of 1:1 exhibited the best ORR performance in alkaline media among the series, with a high halfwave potential of + 0.81 V vs. RHE. Notably, the resultant GO-Zn/Co nanocomposites exhibited an apparent antibacterial activity, inhibiting the formation of biofilms on the cathode surface. An MFC using the as-prepared GO-Zn/Co as the cathode catalyst achieved a maximum power density (773 mW m−2) that was even higher than that with state-of-art Pt/C catalyst (744 mW m−2), and the power output remained virtually unchanged during continuous operation for one month. The results suggest that the GO-Zn/Co nanocomposites can serve as a viable alternative for MFC cathode catalysts.