Electrodes materials evaluation in plant microbial fuel cells: a comparison of graphite and stainless steels

Abstract

The plant microbial fuel cell (PMFC) is an unexpected source of electricity. However, several constraints must be overcome before PMFC can be used as a bioelectricity source. One of the major challenges is to improve electrode performance. In this study, three types of electrodes were tested on PMFC planted with chlorophytum sp, two are made of stainless steel (SS) 436, (SS) 316 and the third is with graphite. The plant with graphite has showed a high tension OCV (400 mV) compared to SS 436 (106 mV) and SS 316 (150 mV), by investing further, the chronoamperometry had shown a more significant current 2 A/m2 with graphite electrode than SS 316 with maximal value 0.12 A/m2 while the SS 436 electrode had metal deterioration, this was later confirmed by a Tafel test, in which SS 436 had the highest current corrosion density. As expected, the maximum current and power densities of PMFC with graphite electrode achieved 20.4 mA/m2 and 37 µW/m2 respectively that were higher than that densities of the PMFC with SS 316 (5.33 mA/m2 and 23 µW/m2) and the PMFC with SS 436 (2.2 mA/m2 and 10.5 µW/m2). According to the finding of this study, graphite was found to be the most suitable electrode material for PMFC application using rhizospheric soil.