PTFE-based hydrophobic layers influence bioelectrical performance of sediment microbial fuel cells with floating air-cathode.

Sediment microbial fuel cells (SMFC) provide scalable power generation, but their low performance is primarily due to poor oxygen reduction reaction (ORR) at cathode. The study aims to improve ORR efficiency by constructing triple-phase interphase (TPI) with multiple hydrophobic polytetrafluoroethylene (PTFE) layers on floating air-cathode. Multiple PTFE layers of 0 (HL0), 1 (HL1), 2 (HL2), 3 (HL3), 4 (HL4), 5 (HL5) and 6 (HL6) are coated on single-sided cathode by brushing method. HL3 generates the highest output current of 204 mA, which is three times higher than control case (HL0). The polarization test shows that HL3 achieves the highest maximum power of 48.88 mW/m2, which corresponds to a 6.8-fold increase compared to HL0 (7.06 mW/m2). HL4 performance improves over time but requires long start-up time before increase in bioelectricity production was achieved. Hydrophobic PTFE layer increases the maximum power density of floating air-cathode, mitigates cathodic limitations and improves SMFC performance. The schematic SMFC reactor with PTFE-based floating air cathode to improve bioelectricity generation. [Display omitted] • Hydrophobic PTFE layers on floating air-cathode improve oxygen reduction reaction. • Multiple PTFE layers were deposited on a single-sided cathode by brushing method. • Highest current output in three PTFE layers with a threefold increase than control. • Multiple PTFE layers increase greatly the maximum power density of SMFC system. • Hydrophobic PTFE layer optimizes cathodic performance and overall SMFC performance. [ABSTRACT FROM AUTHOR]