Engineering a membrane based air cathode for microbial fuel cells via hot pressing and using multi-catalyst layer stacking

Abstract

Microbial fuel cell (MFC) cathodes must have high performance and be resistant to water leakage. Hydrophobic poly(vinylidene fluoride) (PVDF) membranes have shown great advantages in providing a waterproof diffusion layer for MFCs and reducing the cathode costs. However, previous approaches have lacked a method to integrate the diffusion layer into the cathode structure. Here, a hot pressing was used to bind the PVDF diffusion layer onto the air side of the activated carbon cathode, and additional catalyst layers were added to improve performance. Cathodes pressed at 60 °C produced a 16% higher maximum power density of 1630 ± 10 mW m⁻² than non-pressed controls (1400 ± 7 mW m⁻²). Cathode performance was further increased to 1850 ± 90 mW m⁻² by catalyst stacking, through the addition of an extra catalyst layer (CL), which better utilized the available surface area of the stainless steel mesh (SS) current collector. The use of one stainless steel current collector and two catalyst layers (SS/2CLs) produced more positive cathode potentials compared to other designs (SS/CL or 2SS/2CL). Low material costs and high power production for MFCs using these cathodes could enable more cost effective power production using MFCs.