Enhancing Electron Transfer in a Biomimetic Nanocomposite Electrode for Microbial Fuel Cell Applications

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Microbial fuel cells (MFCs) have emerged as a renewable energy source due to their ability for direct conversion of organic substrates into electrical energy. However, issues with low power density, limited long-term stability, and higher operational costs have slowed larger scale integration and adoption. One main factor impacting fuel cell performance is the bacterial interactions at the electrode interface and the associated electron transfer mechanisms which are being widely studied. To increase productive interactions between the microbes and anode, this work focused on the synthetic design of a conductive polysaccharide-based (i.e., agar, alginate, pectin) nanocomposite material. More specifically, metal-carboxyl (Fe3+ or V5+)coordination chemistry was used to photoinitiate the polymerization of polyaniline (PANI) directly on the backbone of the biopolymer matrix increasing the overall uniformity. Results show that the n-doped conducting polymer nanocomposite has enhanced current flow when exposed to E. Coli. Additionally, the electrode surface was modified via non-covalent linkages of organic fuels, such as glucose, with TiO2 nanoparticles to decrease bacteria-surface repulsions. Initial results show that the sugar functionalized electrodes demonstrated an increased electric response in conjunction with photochemical activity. This phenomenon was observed through decreased fluorescence intensity without a decrease in cell viability as well as increased open circuit potential in the presence of light. This ligand-metal charge transfer coupled with increased conductivity of a biomimetic bulk material has resulted in an overall improved MFC system.