Carbon-Supported Spinel Nanoparticle MnCo2O4 as a Cathode Catalyst towards Oxygen Reduction Reaction in Dual-Chamber Microbial Fuel Cell

Abstract

The poor kinetics of oxygen reduction reaction (ORR) in neutral media and ambient temperature limit the performance of microbial fuel cells (MFCs). So higher-performing, low-cost oxygen reduction catalysts play a key role in power output. Through direct nanoparticle nucleation and growth on carbon black, a nanocomposite of manganese cobaltite and carbon black (in situ-MnCo2O4/C) was synthesized via a facile hydrothermal method. Subsequently, the in situ-MnCo2O4/C samples were characterized. The results show that the MnCo2O4 nanoparticles with a crystalline spinel structure are well dispersed on carbon black. Electrochemical measurements reveal that in situ-MnCo2O4/C demonstrates excellent ORR catalytic activity, which may account for the synergetic coupling effect between MnCo2O4 and carbon black. The ORR on as-prepared in situ-MnCo2O4/C hybrid mainly favours a direct 4-electron reaction pathway in alkaline solution. Moreover, in situ-MnCo2O4/C was used as an alternative catalyst for ORR in dual-chamber MFC. The obtained maximum power density is 545 mW m–2, which is far higher than that of the plain cathode (Pmax = 214 mW m–2) and slightly lower than that of commercial Pt/C catalyst (Pmax = 689 mW m–2). This study implies that in situ-MnCo2O4/C nanocomposite is an efficient and cost-effective cathode catalyst for practical MFC application.