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cascade of membrane components is called the proton motive force. The
electrons reach the anode, creating a negative anodic potential, while the
protons go to the cathode, creating a positive potential. The difference
between positive cathodic and negative anodic potentials is expressed as cell
voltage. The cell voltage drives electrons from the anode to the cathode
(electron motive force). Overall, the electron transfer from its source to sink
is purely based on the differences in the redox potentials of the components
of the fuel cell, irrespective of their nature (biological, chemical, or physical).
The MFC’s function as a power generator was well established by using a
wide range of substrates such as electron donors and acceptors in the anode
and cathode chambers, respectively.

6.4.1.1.1 Factors Influencing Bioelectrogenic Activity of MFC
The bioelectrogenic activity of the MFC is governed by several physical,
biological, and operational factors (Venkata Mohan et al., 2013a). Physical
components such as fuel cell design and configuration, electrode materials,
membrane, and stacking regulate the bioelectrogenic activity significantly.
Based on the physical separation of fermentation (anode) and respiration
(cathode), fuel cell configuration can be either dual chambered or single
chambered (Figure 6.3). Anode and cathode chambers are separated by a
PEM in a dual-chamber system, while in a single-chamber configuration,
only the anode chamber is present. The anode is immersed in liquid medium
(anolyte) and the cathode is exposed to air. The electrogenic efficiency of the
MFC varies with electron acceptor conditions. Oxygen (O 2 ) is considered
to be the best known electron acceptor in the biological redox system. Apart
3+ 2+
from O 2 ,Fe (potassium ferricyanide), and Mn (potassium permanga-
nate) are the most studied electron acceptors in dual chamber MFC as cath-
olytes (You et al., 2006). However, using metals as electron acceptors has
drawbacks such as replenishment after exhaustion and their discharge. Per-
formance of MFC was independent of anolyte volume because the possible
+
theoretical potential is around 1.2 V [NAD ( 0.32 V) and O 2 (+0.816 V)].
Stacking smaller MFCs in a series result in a cumulative voltage output.
The nature of solid electron acceptors (electrodes) also influences the
power generation efficiency because of their role as intermediary electron
shuttlers. Electrodes should be electrically conductive, biocompatible, and
chemically stable in an anolyte as well as efficient electron discharge agents.
They should sustain their properties with time and be of a nonfouling
nature. Apart from carbon-based materials, the usage of platinum, titanium,
vanadium, nickel, stainless steel, aluminum, brass, and copper was also