Dynamically controlling the electrode potential of a microbial fuel cell-powered biocathode for sensitive quantification of nitrate

Abstract

Microbial fuel cell (MFC) powered biocathode sensors are promising for self-powered monitoring of water contaminants. However, the extensive electrode potential fluctuation would occur when the MFC powered biocathode were used for detecting different concentrations of target analytes, which in turn limits the sensitivity and accuracy. To address this, for the first time, an electrokinetic model for the nitrate reduction by an MFC powered biocathode was developed. Interestingly, both the theoretical simulation and experimental results disclosed an optimal external resistance, under which the biocathode potential was dynamically controlled in the range that electron transfer from the electrode to the nitrate though biocathodic reduction was kinetically saturated, and the output current was exclusively nitrate concentration depended. With this basis, an MFC powered biocathode sensor was for the first time developed, which showed an extremely low limit of detection (0.11 μM) and wide linear detection range (1–500 μM) in nitrate detection. Moreover, this biosensing system also exhibited good reusability and excellent reliability in complex wastewater environment. This work developed an MFC powered biocathode sensing system with excellent nitrate detection capacity, and demonstrated a novel strategy to accurately quantify the target analytes with dynamically controllable electrode potential.