The present study
reports about the fabrication of a three-dimensional
(3D) macroporous steel-based scaffold as an anode to promote specifically
bacterial attachment and extracellular electron transfer to achieve
power density as high as 1184 mW m–2, which is far
greater than that of commonly used 3D anode materials. The unique
3D open macroporous configuration of the anode and the microstructure
generated by the composite coating provide voids for the 3D bacterial
colonization of electroactive biofilms. This is attributed to the
sizeable interfacial area per unit volume provided by the 3D corrugated
electrode that enhanced the electrochemical reaction rate compared
to that of the flat electrode, which favors the enhanced mass transfer
and substrate diffusion at the electrode/electrolyte interface and
thereby increases the charge transfer by reducing the electrode overpotential
or interfacial resistance. In addition, bacterial infiltration into
the interior of the anode renders large reaction sites for substrate
oxidation without the concern of clogging and biofouling and thereby
improves direct electron transfer. A very low overpotential (−27
mV) with a very low internal resistance (7.104 Ω cm2) is achieved with the fabricated microbial fuel cell (MFC) that
has a modified 3D corrugated electrode. Thus, easier and faster charge
transfer at the electrode–electrolyte interface is confirmed.
The study presents a revolutionary practical approach in the development
of highly efficient anode materials that can ensure easy scale-up
for MFC applications.