Percarbonate as a naturally buffering catholyte for microbial fuel cells

• The new percarbonate catholyte provides good performance in MFCs.
• Percarbonate provides natural buffering capacity.
• Percarbonate prevents biofouling and safe to use.

Sustainable cathode development has been a challenge for the emerging microbial fuel cell (MFC) technology. This study presents a simple catholyte called sodium percarbonate to serve as a new type of electron acceptor for MFCs. Lab scale comparisons showed sodium percarbonate cathode obtained comparable power density (9.6 W/m3) with traditional air–cathode and potassium ferricyanide, but percarbonate showed multiple additional benefits that no other catholyte had demonstrated. Percarbonate has a sustaining natural buffering capacity that can counter pH fluctuations seen in many other systems, and the peroxide produced prevents bio-fouling problems associated with air–cathodes. It is also safer to use and has the lowest cost among popular cathode options based on per mole of electron transferred, which makes it a good candidate for modular system scale up.