A monolithic air cathode derived from bamboo for microbial fuel cells

Abstract

To simplify the cathode fabrication, we herein report a bamboo charcoal tube-derived (BCT) air cathode for microbial fuel cells (MFCs). This monolithic cathode was prepared by carbonizing a bamboo tube in a N₂ atmosphere at 900 °C. The scanning electron microscope indicates that the porous structure of the BCT cathode can provide possible channels for oxygen supply and proton transfer, and therefore can offer the formation of the triple phase interfaces required for oxygen reduction reaction (ORR) in the bulk of BCT. It is also shown that compared to the cathode with bamboo charcoal powder (BC) and Pt/C, the BCT cathode exhibited the lowest oxygen mass transfer coefficient of 4.5 × 10⁻⁵ cm s⁻¹. Additionally, the rotating ring-disk electrode tests demonstrate that the BCT cathode exhibited a considerable activity toward ORR. Consequently, the MFC with BCT delivered a comparable maximum power density (40.4 ± 1.5 W m⁻³) to that with Pt/C (37.7 ± 2.5 W m⁻³) and the highest coulombic efficiency of 55.87 ± 1.0% as compared with the MFCs with BC (29.9 ± 0.4%) and Pt/C (17.2 ± 0.4%). These results indicate that BCT could serve as a low cost, simple fabrication and high-performance alternative cathode for MFCs.