A slurry electrode based on reduced graphene oxide and poly(sodium 4-styrenesulfonate) for applications in microbial electrochemical technologies

Abstract

• A slurry electrode was synthesised using reduced graphene oxide. • Electronic percolation was established at a particle loading of only 2% (wt.) • The slurry displayed shear thinning behaviour, which favours upscaling. • Fluidisation enabled 4.7x higher electro-catalytic current production with microbes. A reduced graphene oxide slurry electrode was prepared via electrochemical reduction of graphene oxide, using anionic surfactant poly(sodium 4-styrenesulfonate) to stabilise the suspension. The slurry electrode was characterised for its electrochemical and rheological properties and tested for its application in a microbial electrochemical system under both static and fluidised conditions. Thanks to the high ratio of lateral dimension to thickness, reduced graphene oxide allowed electronic percolation at a particles loading of only 2% (wt.), which is significantly lower than typically applied with other graphitic materials such as activated carbon. The slurry displayed shear thinning behaviour, which is advantageous in real scale applications to guaranteeing homogeneity during fluidisation and to prevent sedimentation under static conditions. When tested under fluidised conditions in a microbial electrochemical device seeded with a mixed microbial consortium, the slurry enabled a 4.7x improvement of catalytic current production compared to static conditions. This approach may represent an important step toward increasing competitiveness and applicability of microbial electrochemical technologies.