Addressing the global challenge of sustainability calls for cost-effective and eco-friendly pathways to go beyond the existing energy-intense synthetic routes. Biohybrid electrochemical systems can synergistically combine the strengths of biocatalysts and synthetic electrodes to leverage the power of the intercellular metabolism for energy conversion and chemical synthesis using (photo)electrochemistry. Of particular interest are electroactive bacteria with the naturally evolved ability to electrically interact with insoluble metal oxides for anaerobic respiration, which promises broad applications in microbial fuel cells, microbial electrosynthesis and bioremediation. Nevertheless, the development of microbial hybrid systems is perennially plagued by the low power output and volumetric productivity, arising from the imperfect integration of bacteria with solid-state materials. The nexus of breakthroughs, therefore, lies in the electrode architecture and biological interfaces.
Electroactive bacteria are present in a whole host of environments and have recently garnered attention for both, fundamental studies, and emerging applications such as microbial fuel cells. G. sulfurreducens is amongst the most common and promising of these and devices featuring these species have attained some of the highest current densities to date. While the mechanistic details of the EET mechanism of G. sulfurreducens – loaded electrodes in anodic mode are beginning to emerge, the recently established cathodic mode remains rather ambiguous. To shed light on the mechanism of G. sulfurreducens EET, we carried out an extensive study on their biofilms as they grow on electrodes in both anodic and cathodic reaction modes, utilizing electrochemistry, Raman spectroscopy, quartz crystal microbalance measurements, and electron microscopy, with a focus on the role of cytochromes under these two conditions.
Overall objectives of the project:
-Development of a high-performing electrode for microbial electrogenesis and microbial electrosynthesis
-Development of photoanodes for microbial electrosynthesis
-Investigation of bacterial extracellular electron uptake (cathodic) mechanism
