Electrochemical Impedance Spectroscopy as a Powerful Analytical Tool for the Study of Microbial Electrochemical Cells

In microbial electrochemical cells (MXCs), not only classic overpotentials known from other types of fuel cells are encountered, but also overpotentials associated with the metabolic processes and electron-transport pathways in bacteria are encountered. Of the many techniques that can be used to investigate the contributions of various processes to the total overpotential in MXCs, this chapter focuses on electrochemical impedance spectroscopy (EIS). This technique is an alternating current technique that involves applying sinusoidal voltage amplitude over a range of frequencies to investigate the processes that control the overall i–V response. The use of EIS allows differentiating these various processes, as they are often manifested at different frequencies. We discuss the principles and theory behind EIS, especially with respect to its use in MXCs, as well as important experimental methods and design parameters. We show that EIS is an important method that can be used to characterize Ohmic resistance, electrode processes, or an MXC as a whole