Driving force of the better performance of metal-doped carbonaceous anodes in microbial fuel cells

A comparison between different metal-doped carbonaceous anodes for air-breathing microbial fuel cells (MFCs) has been carried out in this work. In order to do that, the surface of carbon paper anodes were modified with Pt, Au and Ni. The current generated was higher when using these metal-doped anodes, exerting up to 7.4 A m−2 more than when using non-doped ones. Polarization curves results in a great performance of the Ni reaching 2.92 W m−2 at the steady state, followed by 0.99 W m−2 of the Au and 0.52 W m−2 of the Pt. Additionally, from the mathematical fitting of a model to the experimental data of a polarization curve, it was observed that the mechanism that explains the better performance of the metal doped anodes was the reduction of the mass transfer limitations. In this sense, the addition of metal on the anodes increase the threshold current density causing mass transfer limitations, reducing also the significance of the mass transfer limitations when the cells are operated under conditions in which the process is diffusion controlled.