A novel and high performance activated carbon air-cathode with decreased volume density and catalyst layer invasion for microbial fuel cells

Abstract

To enhance the performance of activated carbon air cathodes for microbial fuel cells (MFCs), scattered and dense air-cathodes are fabricated by the rolling-press method with the gas diffusion layer or the catalyst layer (CL) invaded to stainless steel meshes (SSM). The maximum power density with scattered cathodes (2503 ± 61 mW m⁻²) is 29% higher than those of dense cathodes because of the decreased internal resistance and increased oxygen reduction reaction activity. The decrease in the electrode volume density and invasion of CL into SSM has been demonstrated to be an optimal structure, with the highest exchange current density up to 1.26 A m⁻² and the lowest charge transfer resistance as low as 1.5 Ω. The increase in performance is believed to result from the enhanced mass transport through extra pores and the contact of activated carbon to the current collector. This novel structure of an air-cathode has a promising future as an application in MFCs.