Fabrication and characterization of graphite-cement composites for microbial fuel cells applications

Graphite-cement composites, with graphite up to 80% w/w, were prepared and characterized. The key feature of this novel material is its conductive and porous microstructure, due to a synergic effect between cementitious matrix and graphite particles. As graphite content increases, a characteristic percolation threshold exists. The threshold value depends on curing temperature and determines a remarkable change in electrical, physical and mechanical properties. In the proximity of the threshold, conductivity increased from 3.2∙10−5 S m−1 to 2 S m−1 and porosity increased from 48% to 60%. Compressive strength indicates a similar behaviour and thermally cured composites exhibit higher strength. The thermally treated composite with 50% w/w of graphite is chosen for electrochemical analysis. Cyclic voltammetry and kinetic study with linear sweep voltammetry confirmed that these materials can catalyse cathodic reactions with an interesting current density and low overpotential. The graphite-cement composite developed is an eligible material for microbial fuel cell applications.