Electrochemically activated carbon nanotube anodes for enhanced microbial fuel cell performance

Abstract

Carbon nanotube (CNT) modified anodes in microbial fuel cells (MFCs) face limitations in startup time and power output due to slow microorganism colonization and poor extracellular electron transfer (EET). This is often caused by the hydrophobic nature and low specific capacitance of high-temperature synthesized CNTs. This study presents a novel approach to overcome these limitations by developing a hydrophilic and high-capacitance anode using electrochemically activated iron and nitrogen-doped CNTs (A-FeNCNTs) on carbon cloth (CC). A-FeNCNTs@CC demonstrates significantly improved biocompatibility and charge storage capacity compared to pristine CC. In MFC tests using mixed cultures, A-FeNCNTs@CC achieved a faster startup time of 1.8 days (1.5 days shorter than CC) and a higher power density of 3.07 W/m² (about 1.58 times that of the CC anode). Additionally, chemical oxygen demand (COD) removal efficiency reached 91.82%, surpassing CC (74.93%). The enhanced performance is attributed to the synergistic effects of increased hydrophilicity and capacitance, promoting robust biofilm formation and efficient EET. This work establishes a promising strategy for tailoring the physicochemical properties of carbon-based anodes, leading to significant advancements in MFC performance and demonstrating the potential of A-FeNCNTs@CC for enhanced bioelectricity generation and wastewater treatment.