High power density redox-mediated Shewanella microbial flow fuel cells

Area of Science:

• Electrochemistry
• Microbiology
• Environmental Engineering

Background:

• Microbial fuel cells (MFCs) convert organic matter to electricity using exoelectrogenic microorganisms.
• Conventional MFCs face a tradeoff between biofilm thickness for electron production and mass/charge transport, limiting power density (<1 mW cm⁻²).

Purpose of the Study:

• To develop a biofilm-free MFC design overcoming transport limitations.
• To enhance power density through efficient electron transfer from planktonic bacteria.

Main Methods:

• Utilized artificial redox mediators in a flowing medium for electron transfer.
• Employed planktonic bacteria instead of thick biofilms.
• Designed a redox-mediated microbial flow fuel cell (MFC).

Main Results:

• Achieved efficient electron transfer from planktonic bacteria to electrodes.
• Overcame mass and charge transport limitations, reducing internal resistance.
• Demonstrated a maximum current density >40 mA cm⁻² and peak power density >10 mW cm⁻².

Conclusions:

• The redox-mediated MFC design effectively breaks the biofilm tradeoff.
• Achieved power densities approximately one order of magnitude higher than state-of-the-art MFCs.
• Offers a promising approach for efficient bioelectricity generation and wastewater treatment.