Prussian blue/graphene-modified electrode used as a novel oxygen reduction cathode in microbial fuel cell

Abstract

Prussian blue/graphene (PB/GE) nanocomposite was successfully synthesized and the oxygen reduction reaction (ORR) activities were studied in our previous work. In this study the PB/GE nanocomposite and PB were deposited on the surface of active carbon particles, and the resulted particles were placed in two microbial fuel cells (MFC) as the three-dimensional cathode electrodes for oxygen reduction. The two MFCs were labeled as PB/GE-MFC and PB-MFC, and their performances were evaluated in the long term operation. A series of characterization methods showed the successful deposition of PB/GE and PB on the particles. After the long term operation, the cell voltage and maximum power density of PB-MFC decreased sharply, which dropped from 530 mV and 15.63 W/m−3 to 395 mV and 7.5 W/m−3, while those of PB/GE-MFC were decreased slightly, which dropped from 530 mV and 16.26 W/m−3 to 470 mV and 15.88 W/m−3. The Tafel constants showed that PB/GE-MFC cathode had higher kinetic activity and faster reactions than PB-MFC cathode. PB/GE had stable performance in the MFC during the long term operation, and it can be used as a novel cathode as an effective alternative to platinum for oxygen reduction in MFC.