Untreated vs. Treated Carbon Felt Anodes: Impacts on Power Generation in Microbial Fuel Cells

Area of Science:

• Bioelectrochemical Systems (BESs)
• Microbial Fuel Cells (MFCs)
• Carbon Materials Science

Background:

• Optimizing anode materials is crucial for enhancing the efficiency and scalability of bioelectrochemical systems (BESs).
• Carbon felt (CF) is a promising anode material due to its porous structure, but its surface properties can be modified to improve performance.
• Surface modifications aim to increase hydrophilicity, reduce internal resistance, and expand the electrochemically active surface area.

Purpose of the Study:

• To investigate the impact of acid-heat treatment and chemical modification on the performance of carbon felt (CF) anodes in microbial fuel cells (MFCs).
• To evaluate the efficacy of coating CF with carbon nanofibers (CNFs) using SDBS surfactant and chitosan (CS) biopolymer.
• To determine the most effective CF anode configuration for maximizing power generation in BESs for potential large-scale applications.

Main Methods:

• Acid-heat treatment and chemical modification of pristine three-dimensional porous carbon felt (CF).
• Coating CF with carbon nanofibers (CNFs) using dodecylbenzene sulfonate (SDBS) and chitosan (CS).
• High-resolution scanning electron microscopy (HR-SEM) for surface morphology analysis and electrochemical analysis (e.g., cyclic voltammetry, electrochemical impedance spectroscopy).
• Testing anode performance in an air cathode single-chamber MFC system.

Main Results:

• HR-SEM confirmed successful CNF coating on CF anodes.
• Electrochemical analysis indicated improved conductivity and charge transfer with treated anodes using a [Fe(CN)6]3-/4- redox probe.
• Untreated CF anodes demonstrated faster electroactive biofilm growth and achieved a maximum power output density of 3.4 W m-2 with an open-circuit potential of 550 mV.
• Treated CF anodes showed reduced charge transfer resistance (Rct) but did not result in increased power densities compared to untreated CF.

Conclusions:

• Untreated carbon felt (CF) anodes appear most promising for enhancing power output in bioelectrochemical systems (BESs), specifically microbial fuel cells (MFCs).
• Despite surface modifications improving certain electrochemical properties, they did not translate to higher power generation.
• Untreated CF offers a potentially cost-effective solution for large-scale MFC applications, warranting further investigation into its inherent advantages.