The applicability of microbial electrosynthesis (MES)
for chemical synthesis from carbon dioxide (CO2) requires improved
production and energetic efficiencies.
Microbial catalysts, electrode
materials, and reactor design are the key components which influence the
functioning of such processes. In particular, cathode materials critically
impact the electricity-driven CO2 reduction process by
microorganisms. Interest in cathode surface modifications for improving MES
processes is thus consistently increasing.
In this paper, the recent
developments and spatial modification of cathode materials for microbial CO2
reduction are systematically reviewed. The characteristics of
commercially available materials, their modifications, and developments in new
materials that have been used as cathodes for MES are summarized.
Key cathode–microorganism interactions that led to
improved CO2 conversion are then discussed The cathode surface
modification approaches have focused mainly on improving the surface area and
surface chemistry of the materials. Although the modified cathode surfaces
improved biofilm growth in direct electron uptake based bioconversions, they
have achieved lower acetate production rates than that of hydrogen-based MES
processes thus far.
Research efforts on
different materials suggest that the three-dimensional cathodes that can retain
more biomass, in particular in hydrogen-based bioconversions, are promising for
further improvements in production efficiencies. Further efforts toward
reducing the energy inputs for achieving energetically efficient MES processes
by using electrocatalytically efficient cathodes are needed.