Exploring the use of polyaniline-modified stainless steel plates as low-cost, high-performance anodes for microbial fuel cells

Highlights: • Improved uniform and adherent polyaniline (PANi) coating on SS plate (SS-P). • Significant influence of the nature of PANi coating on SS-P on stability and performance. • Rapid improvement in MFC start-up time induced by PANi coating in SS-P/PANi anode. The provision of optimum medium for microbial growth and maintenance of long-term stability for microbial fuel cells (MFCs) is very much dependent on the chosen anode material. However, the chosen material must also be readily available and cheap in order to attract wider use and broader adoption of MFCs. In this study, we explored the use of polyaniline (PANi) modified stainless steel plates (SS-Ps) as potential low-cost anodes for MFCs, with capability for effective promotion of microbial growth and retention of long-term stability. Careful and selective choice of acid and aniline concentrations for galvanostatic polymerisation produced highly uniform and adherent conductive PANi coating on SS-P which are desirable for use as anodes in MFC. The resulting PANi modified SS-P (SS-P/PANi) was evaluated as a low-cost anode for MFCs in a simulated wastewater which composed of a M9 media and 4% landfill leachate. The SS-P/PANi anode performed efficiently in a MFC, achieving a 13-fold higher current generation than with a pristine SS-P anode during the startup phase. Also, it achieved higher OCV_max of 730 ± 42 mV, j_max of 0.14 ± 0.12 mA cm⁻² and a P_max of 0.078 ± 0.011 mW cm⁻². In comparison, the SS-P anode achieved lower OCV_max of 649 ± 37 mV, j_max of 0.009 ± 0.011 mA cm⁻² and P_max of 0.010 ± 0.008 mW cm⁻². Furthermore, the achieved current and power densities with the SS-P/PANi anode were superior to those obtained with a previously reported PANi modified stainless steel fibre felt (SSFF) anode. Thus, demonstrating the suitability of the SS-P/PANi electrode for adoption as a low-cost, high-performance anode for MFCs.