Characterising operational performance and oxygen crossover of the low-cost cylindrical cathode in microbial fuel cells

The cylindrical cathode has been used in microbial fuel cells (MFC) to achieve a large cathode area and high operational performance. However, the high material cost of cylindrical cathodes limits their practical application. To overcome this, a low-cost cylindrical cathode was successfully developed by coating activated carbon-based catalysts uniformly on the surface of cylindrical stainless steel mesh. The MFCs with the low-cost cylindrical cathodes could obtain a large surface area (up to 509 m2/m3), high power density (81.4 W/m3) and fast organic matter removal rate (−0.32 h−1). However, long-term operation showed that a cathode area larger than 104 m2/m3 could induce excessive oxygen crossover and substantially reduce the power stability of MFC. A numerical study showed that the oxygen crossover was affected by cathode properties such as surface area, current and biofilm. Accordingly, potential controlling methods were proposed. This study will benefit the practical application of cylindrical cathodes.