Titanium dioxide thin film-modified stainless steel mesh for enhanced current-generation in microbial fuel cells

In this paper, a TiO2 thin film-modified stainless steel mesh (SSM/TiO2-H) was prepared by an electrochemical method and applied as an anode in microbial fuel cells (MFCs) to enhance their power output. A maximum projected current density of 69.5 ± 1.2 A/m2 was obtained from our SSM/TiO2-H electrode. This high current was attributed to the favorable biocompatibility of the electrode. We measured a total protein density of 2431 ± 224 μg prot/cm2 on the SSM/TiO2-H electrode after 20-days of cultivation, which was approximately 12 times greater than that of the untreated SSM. In addition, electrochemical impedance spectroscopy showed that the charge transfer resistance between the biofilm and electrode was only 3.55 Ω and a thick and dense biofilm was measured on the surface of SSM/TiO2-H (28.3 ± 0.5 μm). All peaks occurred at −0.30 ± 0.05 V in differential pulse voltammetry curves, indicating that the high current showed no contributions from changes of the exocellular electron transfer components. These results should guide future studies of stainless steel mesh for applications in MFCs. Our method represents a new approach to achieve high energy output anode through modifying the properties of titanium dioxide thin films.