Enhancing oxygen reduction reaction of microbial fuel cells with binary nanohybrid

Recently population growth and modernization have extensively raised the global demand for clean energy and water. Environmental pollution and global warming caused by ever-increasing energy demand contribute to the urgency for new renewable and reliable energy sources to attain sustainable development. Hence, this has made an urgent search for development of energy efficient and environmental friendly methods for sustainable wastewater treatment and energy production. As a potential renewable feedstock to overcome the energy crisis and environmental problems, a surplus of harvestable, sustainable, green and renewable energy is found in organic waste or wastewater. Recently, microbial electrochemical technologies, including microbial fuel cells (MFCs) as a “green” energy-producing device, can directly generate electrical energy from the degradation of organic wastes to smaller molecules through using microbes respiration [۱,۲]. However, real applications of MFCs are limited because of their low small scale power yield and high cost of materials, in particular catalysts used to enhance the oxygen reduction reaction (ORR) at the cathode side [۳].In this work we developed a novel, facile, and low-cost synthesis to prepare multivalent silver vanadate supported on multiwall carbon nanotubes as ORR catalyst. The ORR performance of as-synthesized catalysts was investigated in O۲-saturated ۰.۱ M phosphate buffer solution using the typical three-electrode system. Among the prepared materials, silver vanadate supported on multiwall carbon nanotubes showed the highest catalytic activity toward the ORR due to a good combination between surface chemistry and morphology. As well as, the modified multiwall carbon nanotubes altered the ORR from the original two-electron pathway to four-electron pathway (electron-transfer number of ۴). A maximum power density of ۱۰۰ mW cm–۲ was produced in MFCs using this cathode catalyst in ۰.۱ M phosphate buffer solution. The use of this silver vanadate supported on multiwall carbon nanotubes as cathode catalyst can therefore substantially improve power production, and its use could enable practical applications of microbial fuel cells for wastewater treatment