A particular advantage of biological cells is their ability to organize a sequence of complex reactions to produce specific components required by the cell. This has originated the term “microbial power and energetics” which attracts different scientific domains towards this single broad confluence of “bio-electrochemistry”. Owing to these, I continued my research with specific orientation towards bioenergetics and bio-electrochemisty that encompasses microbes that are capable of releasing electrons while digesting a variety of substates like carbohydrates, proteins, alcohols, recalcitrant materials like cellulose, etc as food. Microbial fuel cells (MFC) is a bio-electrochemical cell that uses this microbial power known as biocatalysis where these electroactive microbial species e.g., Lysinibacillus, Geobacter and Shewanella produces bioelectricity using a wide stream of substrates. MFC constitutes three major components: (i) Anode: where, microbes oxidize (degrades) different substrates and releases electrons (e^-) and protons (H⁺). (ii) Cathode: The generated electrons and protons at anode migrates and gets accepted here, finally transforming oxygen into water as a process known as reduction. (iii) Proton/Ion exchange membrane : This separates the anode and cathode compartment and allows the generated protons to migrate towards cathode (Figure shown below). In the whole process, there is flow of electrons known as bioelectricity that resembles a small green battery, which is far economical in terms of substrates required by the system. This direct electron transfer (DET) from microbes to electrodes exhibits (a) redox enzymes capable of DET at the surface of an electrode (b) stability of microbes and electrodes for bioelectricity generation, and (c) subsequent remediation by anolyte oxidation.

The major limiting factor in MFC fabrication is the used separator/barrier membrane that alone contributes to ~ 40% of the total unit cost. Commercial membranes like Nafion^TM, Ultrex^TM etc have been widely used in MFCs as separators that have major limitations in terms of cost efficiency and usage. However, there are several other small but major components that are included in the system. Owing to that, I worked on development of different polymeric materials as promising separator materials in fuel cell application. Different semi-IPNs (Interpenetrating network), nanocomposites and sulfonated membranes have been evaluated as alternative low cost ion exchange barriers in MFCs.

These studies have deeply widened my existing knowledge in the domains of bio-electrochemistry, especially in the areas of microbial catalysis that allowed me learning some crucial potentiodyanamic techniques (e.g., Cyclic Voltammetry, Chronoamperometry and Electrochemical Impedence Spectroscopy). These techniques have been employed to understand the aspects of applied current/voltage scans (chronocoulometry, potential bias, etc) for identifying different re-dox active behaviors in the system.