High Power Generation by a Membraneless Single Chamber Microbial Fuel Cell (SCMFC) Using Enzymatic Bilirubin Oxidase (BOx) Air-Breathing Cathode

In this work, for the first time, we showed the successful utilization of enzymatic-based (bilirubin oxidase, BOx) air-breathing gas-diffusion (ABGD-BOx) cathode in membraneless single chamber microbial fuel cells (SCMFCs). At pH range of 7.2–7.5, the cathode open circuit potentials (OCPs) achieved were in the range of 490–535 mV (vs. sat. Ag/AgCl) with the anodic OCP being between −495 mV and −530 mV (vs. sat. Ag/AgCl). The highest overall open circuit voltage (OCV) of the SCMFCs (1.05 V) fed with phosphate buffer solution (PBS) and sodium acetate (NaOAc) was achieved after 12–24 hour of operation. Polarization curves of the ABGD-BOx cathode showed lower overpotential with an advantage of up to 250 mV compared to the traditional platinum Pt-based cathode, and possessed a great potential to replace the noble metal-based cathodes in MFCs. High power generation of 2 W m−2 (200 μW cm−2, referred to cathode geometric surface area) was achieved in SCMFCs with the ABGD-BOx cathode, which was the highest power generation reported for SCMFCs with a volume greater than 100 mL.