Nanomaterials Facilitating Microbial Extracellular Electron Transfer at Interfaces

Abstract

Electrochemically active bacteria can transport their metabolically generated electrons to anodes, or accept electrons from cathodes to synthesize high-value chemicals and fuels, via a process known as extracellular electron transfer (EET). Harnessing of this microbial EET process has led to various microbial bioelectrochemical systems such as bioenergy through microbial fuel cells (MFCs). Despite great progress that has been made in terms of the efficiency and applicability of MFCs in recent years, many issues are waiting to be tackled for practical applications of MFCs. The most important challenges included the relatively low power density and poor energy conversion efficiency of MFCs, which mainly arise from low extracellular electron transfer (EET) efficiency between microorganisms and electrode, and the cost of electrode materials. Thus, how to improve the electron transfer rate at the bacteria/electrode interface is an extremely important issue in MFCs. Herein, we designed and fabricated several nanostructured anodes to increase physical contact between electrode and outer-membrane proteins or microbial nanowires and promote efficient EET efficiency between microorganisms and electrode, leading to a steep improvement in MFC performance. For example, our group fabricated a three-dimensional graphene aerogel electrode coated with platinum nanoparticles. Benefited from the continuous 3D macroporous structure with suitable pore size, both the surface and interior of the electrode were covered with a thin biofilm of S. oneidensis MR-1 after pre-inoculation. The graphene aerogel scaffold decorated with highly conductive platinum nanoparticles resulted in an outstanding maximum power density of 1460 mW/m 2 , 5.3 folds of carbon cloth. The MFCs equipped with the graphene/FeS 2 NPs not only benefits bacterial adhesion and enrichment of electrochemically active Geobacter species on the electrode surface but also promotes efficient extracellular electron transfer, thus giving rise to a fast start-up time of 2 days, an unprecedented power density of 3220 mW m -2 in the acetate-feeding and mixed bacteria-based MFCs and 310 mW m -2 with simultaneous removal of 1319 ± 28 mg L -1 chemical oxygen demand in effluents from a beer factory wastewater. The 3D hierarchical porous carbon foam anodes prepared by pyrolyzing nanoscale Fe-MIL-88b-NH 2 modified seitan composite deliver a maximum power density of 11.21 W m -3 and current density of 23.11 A m -3 , outperforming most previously reported 3D porous anodes. The characteristics of improved power generation and enhanced pollutant removal efficiency open door towards development of high-performance MFCs via rational anode design for practical application.

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Identifiers

DOI

10.1149/ma2025-01422313mtgabs

Journal

ECS Meeting Abstracts

Year

2025