Wastewater treatment and electricity generation via microbial fuel cell using ZnO supported on activated carbon cathode electrocatalyst

Microbial fuel cells are bio-electrochemical devices that use extracellular electron transfer (EET) to promote anaerobic biodegradation of biomass to generate electricity and clean wastewater. In this study, Zinc oxide supported on activated carbon (ZnO/AC) is investigated as a cathode electrocatalyst and compared with a benchmark Pt/C electrocatalyst. Electrochemical measurements of the ZnO/AC electrocatalyst were performed utilizing a rotating disc electrode (RDE) and linear sweep voltammetry (LSV) in a phosphate buffer solution (pH 7). Furthermore, its long-term performance in a single chamber MFC application is assessed by evaluating organic matter elimination and polarisation behaviour. Finally, scanning electron microscopy is used to check the surface morphology of the bio anode. It could be observed that ZnO/AC shows high selectivity towards the oxidation reduction reaction (ORR). In addition, it displays the highest achievable power density generation value of 90.177 mW m-3 at cell current density of 300.295 mA m-3, where the Pt/C cathode generates a high power density of 128.054 mW m-3 at a cell current density of 357.846 mA m-3. Our results indicate that the ZnO/AC cathode is improved electrocatalytic performance toward ORR in a pH-neutral solution, making it a viable substitute for pricey Pt-based catalysis.