Stainless Steel-Based Bioanodes for Applications in Bioelectrochemical Systems

Abstract

The majority of studies focusing on bioelectrochemical systems (BES) report the utilization of carbon-based electrodes. However, in order to overcome the limitations related to the scale-up of Microbial Fuel Cells (MFC) and Microbial Electro Synthesis (MES) cells technologies, the utilization of metal-based electrodes need to be considered due to their conductivity, cost and robustness. Stainless steel fiber felts (SSFF) as bioanode material for BES applications was investigated in this study. The unmodified SSFF was tested alongside with electrodes modified with reduced graphene oxide (rGO), magnetite nanoparticles (Fe3O4), manganese oxide (MnO2) and flame-oxidation (FO). The performance of the metal-based electrodes as bioanodes were investigated in half-cells in terms of stability and current densities. In addition, the impact of the capacitance of the abiotic electrode materials on the performance of the bioanodes and MFCs was evaluated (Fig. a), especially to assess how these materials can increase the energy harvested compared to non-capacitive bioanodes. The results showed that the stainless steel- based electrodes studied are competitive alternatives to the carbon-based electrodes. Current densities recorded in half-cells were 1.96, 1.95 and 2.26 mA/cm2 for FO-MnO2-SS, rGO-SS and carbon cloth, respectively. In addition, charge/discharge experiments carried out with the bioanodes developed (Fig. c) showed that the modified SSFF electrodes allow the storage of electrical charge from the biofilm to the capacitive layers of the electrodes when cells are left at open circuit potential (OCP). These results demonstrate the potential of these materials for energy generation and storage applications from waste in BES. Figure 1