In the limelight of global fossil fuel depletion and environmental deterioration, alternative energy solution that is clean and renewable is greatly desired. Microbial fuel cell (MFC) as a promising candidate could utilize organic compound in wastewater as fuel for power generation, thereby simultaneously tackling the energy and environment problems. Nevertheless, as an emerging field MFC is still in its infancy. It inevitably requires highly disciplinary effort spanning from fuel cell technology, material science, interfacial physics and chemistry, electrochemistry to microbiology. There are considerable number of concepts, experimental methods to streamline both with respect to the fundamental significance and application feasibility of MFC.

To this end, we adopt holistic ap...[ Read more ]

In the limelight of global fossil fuel depletion and environmental deterioration, alternative energy solution that is clean and renewable is greatly desired. Microbial fuel cell (MFC) as a promising candidate could utilize organic compound in wastewater as fuel for power generation, thereby simultaneously tackling the energy and environment problems. Nevertheless, as an emerging field MFC is still in its infancy. It inevitably requires highly disciplinary effort spanning from fuel cell technology, material science, interfacial physics and chemistry, electrochemistry to microbiology. There are considerable number of concepts, experimental methods to streamline both with respect to the fundamental significance and application feasibility of MFC.

To this end, we adopt holistic approach to investigate the interaction of electrochemically active microorganism with electrode. We do not intend to conduct a comprehensive survey because of the multitude and complexity of MFC. Instead, we focus on the core element, the bio-electrode of the representative MFC systems that cover the three major MFC types known to date. For the heterotrophic bacteria based bio-anode, we used Escherichia coli K-12; for the autotrophic biosolar-anode, we used Cyanobacterium Synechocystis PCC 6714; for the autotrophic biosolar-cathode, we used Rhodobacter capsulatus. We emphasized on the electron transport mechanisms of the three types of systems. To study the microbes/electrode kinetics, we fabricated half-cell single chamber and dual chamber electrochemical and photoelectrochemical cells. We employed electrochemical quartz crystal microbalance (EQCM), Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and bioluminescence methods to examine the electron transport at the bio-hybrid electrode.

We established multi-scale view on electron transport. At nanometer scale, we used luciferase to tag the activity of component of electron transport chains. At micrometer scale, we used EIS to evaluate the transport of mediator molecules through the membrane pores of cyanobacteria. At centimeter scale, we investigated cell aggression as biofilm on electrode using EQCM and CV. Moreover, we show that the influence of environmental redox condition on the rate of electron transport is universal for all three types of MFC systems. Therefore, it is a promising method to domesticate bacteria towards enhanced redox active phenotype which is desirable for current generation in MFC.