Anodic concentration loss and impedance characteristics in rotating disk electrode microbial fuel cells

A rotating disk electrode (RDE) was used to investigate the concentration loss and impedance characteristics of anodic biofilms in microbial fuel cells (MFCs). Amperometric time–current analysis revealed that at the rotation rate of 480 rpm, a maximum current density of 168 µA cm^?2 can be achieved, which was 22.2 % higher than when there was no rotation. Linear sweep voltammetry and electrochemical impedance spectroscopy tests showed that when the anodic potential was set to ?300 mV vs. Ag/AgCl reference, the power densities could increase by 59.0  %, reaching 1385 mW m^?2, the anodic resistance could reduce by 19  %, and the anodic capacitance could increase by 36 %. These results concur with a more than 85 % decrease of the diffusion layer thickness. Data indicated that concentration loss, diffusion layer thickness, and the mixing velocity play important roles in anodic resistance reduction and power output of MFCs. These findings could be helpful to the design of future industrial-scale MFCs with mixed bacteria biofilms.