Electrochemical evaluation of different polymer binders for the production of carbon-modified stainless-steel electrodes for sustainable power generation using a soil microbial fuel cell

Abstract

In this study, four different polymeric binders - polytetrafluoroethylene (PTFE), two-component epoxy (epoxy), polyvinyl alcohol (PVA), and polyvinylidene fluoride (PVDF) - were used to fabricate a surface-modified stainless-steel electrode. The polymeric binders were used to bond highly conductive carbon-black to a stainless-steel support using a simple fabrication method. The performance of the electrodes in terms of sustainable power generation was tested in a soil microbial fuel cell (SMFC). PTFE showed the fastest and best initial response in no-load operation, reaching a voltage of 370 mV after 7 days, compared to epoxy, PVA, and PVDF, which had 163, 151.7, and -26.7 mV, respectively. Electrochemical measurements showed that epoxy and PVDF have similar redox potential when operated as anode and cathode in an SMFC. Electrochemical evaluation of the long-term performance of the binders showed that epoxy gave 2.2-, 3.4-, and 4.9-fold higher performance than PVDF, PTFE, and PVA, respectively, under intermittent polarization. Although PVDF did not perform well in open circuits, it produced the highest current density in continuous operation with external loads. The most sustained performance was obtained with epoxy. This study has shown that epoxy can be a suitable and eco-friendly substitute for other binders using a simple fabrication method to produce high-performance anodes and cathodes for sustainable bioelectricity generation with a SMFC.