Carbon‐Based Microbial‐Fuel‐Cell Electrodes: From Conductive Supports to Active Catalysts

Abstract

Microbial fuel cells (MFCs) have attracted considerable interest due to their potential in renewable electrical power generation using the broad diversity of biomass and organic substrates. However, the difficulties in achieving high power densities and commercially affordable electrode materials have limited their industrial applications to date. Carbon materials, which can exhibit a wide range of different morphologies and structures, usually possess physiological activity to interact with microorganisms and are therefore fast-emerging electrode materials. As the anode, carbon materials can significantly promote interfacial microbial colonization and accelerate the formation of extracellular biofilms, which eventually promotes the electrical power density by providing a conductive microenvironment for extracellular electron transfer. As the cathode, carbon-based materials can function as catalysts for the oxygen-reduction reaction, showing satisfying activities and efficiencies nowadays even reaching the performance of Pt catalysts. Here, first, recent advancements on the design of carbon materials for anodes in MFCs are summarized, and the influence of structure and surface functionalization of different types of carbon materials on microorganism immobilization and electrochemical performance is elucidated. Then, synthetic strategies and structures of typical carbon-based cathodes in MFCs are briefly presented. Furthermore, future applications of carbon-electrode-based MFC devices in the energy, environmental, and biological fields are discussed, and the emerging challenges in transferring them from laboratory to industrial scale are described.

Active Salt/Silica‐Templated 2D Mesoporous FeCo‐Nx‐Carbon as Bifunctional Oxygen Electrodes for Zinc–Air Batteries

“…Owing to their unique properties compared with conventional porous carbon analogues, two‐dimensional (2D) porous carbon nanosheets are attracting increasing attention for their potential application in the fields of electronics, sensing, energy storage, and conversion, especially because the 2D morphology with additional porosity increases the accessible surface area for the electrolyte, thus accelerating mass and charge transfer . Recently, several synthetic methods for the preparation of 2D mesoporous carbon nanosheets have been reported, including hard and soft templating approaches using silica nanoparticles or amphiphilic block‐co‐polymers, respectively .…”

Conductive Hydrogels as Smart Materials for Flexible Electronic Devices

“…Carbon-based materials, such as carbon nanotubes (CNTs), graphene,a ctivated carbon, carbon fibers, carbon dots, and porousc arbon are considered to be promising conductive materials for fabricating conductive hydrogels, due to their unique properties of high electrical conductivities, excellent environmental stabilitya nd the low production cost. [65][66][67][68] Amongv ariousc arbon-based materials, CNTsa nd graphene have been widely explored in materials science, and also been intensively used as conductive filler in the conductive hydrogels forf lexible and wearable electronics. Blendingw ith various polymer and self-assembly after modification are the two most common ways for preparing carbon-based conductive hydrogels.…”

High‐Power Microbial Fuel Cells Based on a Carbon–Carbon Composite Air Cathode

“…In an MFC as illustrated in Figure a, exoelectrogenic bacteria in the anode oxidize organics and release electrons traveling through the external circuit to the cathode, where the oxygen reduction reaction (ORR) occurs . In order to reduce the energy consumption of water aeration, air cathodes have been developed . However, several challenges still impede the practical application of MFCs, and the poor ORR kinetics in the air cathode at neutral pH is one of the most crucial obstacles .…”