Stainless steel coated with carbon nanofiber/PDMS composite as anodes in microbial fuel cells

Modification of electrode surfaces is a promising strategy to improve microbial fuel cell (MFC) performance. Here we report a new functionalization process to improve interfacial electron transfer, biocompatibility and corrosion resistance of stainless steel (SS) electrodes used as anodes in MFCs. SS anodes prepared by surface modification with a thin layer (200 mu m) of conducting composite made of polydimethylsiloxane (PDMS) doped with commercially available carbon nanofibers (CNF), are described. Electrochemical characterization showed that the corrosion rate of SS electrode in an acid solution decreased from 367 mu m.y(-1) to 31 mu m.y(-1) after CNF-PDMS coating. Electric characterization demonstrated that the maximum power density generated by MFCs after 16 days with SS/CNF-PDMS anodes (19 mW.m(-2)) is 5 times higher and more stable than that with unmodified SS (3.7 mW.m(-2)). The cyclic voltammetry analysis indicated that the electrochemical activity of the modified anode was enhanced significantly after 16 days and the electron transfer was facilitated by CNF-PDMS modification. Microscopic observations and electrochemical characterization showed that CNF-PDMS-composite improved biocompatibility and corrosion resistance of the SS anode surfaces. These results confirmed that the CNF-PDMS modification is a promising approach to improve the properties of anode materials for MFC application.