Low-cost stainless-steel wool anodes modified with polyaniline and polypyrrole for high-performance microbial fuel cells

A conducting polymer coated stainless-steel wool (SS-W) is proposed for use as a low-cost anode for microbial fuel cells (MFCs). When coated with polyaniline (PANi) and polypyrrole (PPy), the pristine SS-W, SS/PANi-W and SS/PPy-W anodes produced maximum current densities of 0.30 ± 0.04, 0.67 ± 0.05, 0.56 ± 0.07 mA cm⁻², respectively, in air-cathode MFCs. Also, based on achieved power density, both SS/PANi-W and SS/PPy-W achieved 0.288 ± 0.036 mW cm⁻² and 0.187 ± 0.017 mW cm⁻², respectively, which were superior to 0.127 ± 0.011 mW cm⁻² obtained with pristine SS-W. Further, in comparison with SS-P based anodes, all SS-W based anodes gave improved power densities under similar experimental conditions by at least 70%. Moreover, the charge transfer resistance of the SS-W was much lower (240 ± 25 Ω cm⁻²) than for the SS-P (3192 ± 239 Ω cm⁻²). The j_0(apparent) values obtained for SS/PANi-W (0.098 ± 0.007 mA cm⁻²) and SS/PPy-W (0.036 ± 0.004 mA cm⁻²) anodes were also much higher than that of the pristine SS-W (0.020 ± 0.005 mA cm⁻²), as well as than those of all SS-P based anodes. The observed enhancement of the bioelectrocatalytic performances were well supported by physicochemical and electrochemical characterisation.