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Living photovoltaics represent a growing class of microbial devices that are based on whole cell-electrode interactions [1-3]. The limited charge transfer at the cell-electrode interface represents a significant bottleneck in realizing an efficient technology [4]. This study focuses on the development of poly(3,4-ethylenedioxythiophene) (PEDOT)-based electrodes with enhanced charge transfer properties at the interface [5,6]. This is accomplished by the electrosynthesis of PEDOT layers from aqueous sodium dodecyl sulfate (SDS) solutions. Potentiodynamic and potentiostatic electrochemical techniques, as well as scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, and theoretical modelling of the electropolymerization transient, were employed to assembly and characterize PEDOT electrodes under various conditions. The produced electrodes are able to capture photosynthetically derived current under multiple light-dark cycles when interfaced with Synechocystis sp. PCC 6803. In the presence of the Synechocystis, the PEDOT electrodes show a six-fold and two-fold enhancement over conventional graphite electrodes for both mediatorless and K3Fe(CN)6 mediated conditions, respectively. The ability of these electrodes to enhance extracted photocurrent for both direct and indirect electron transfer mechanisms provides a versatile platform for improving various microbial devices. [1] Zou, Y., Pisciotta, J., Billmyre, R. B., & Baskakov, I. V. (2009). Photosynthetic microbial fuel cells with positive light response. Biotechnology and Bioengineering, 104(5), 939-946. [2] Pisciotta, J. M., Zou, Y., & Baskakov, I. V. (2010). Light-dependent electrogenic activity of cyanobacteria. PloS one, 5(5), e10821. [3] Schuergers, N., Werlang, C., Ajo-Franklin, C. M., & Boghossian, A. A. (2017). A synthetic biology approach to engineering living photovoltaics. Energy & environmental science, 10(5), 1102-1115. [4] Mouhib, M., Antonucci, A., Reggente, M., Amirjani, A., Gillen, A. J., & Boghossian, A. A. (2019). Enhancing bioelectricity generation in microbial fuel cells and biophotovoltaics using nanomaterials. Nano Research, 1-16. [5] Tamburri, E., Orlanducci, S., Toschi, F., Terranova, M. L., & Passeri, D. (2009). Growth mechanisms, morphology, and electroactivity of PEDOT layers produced by electrochemical routes in aqueous medium. Synthetic metals, 159(5-6), 406-414. [6] Zajdel, T. J., Baruch, M., Méhes, G., Stavrinidou, E., Berggren, M., Maharbiz, M. M., ... & Ajo-Franklin, C. M. (2018). PEDOT: PSS-based multilayer bacterial-composite films for bioelectronics. Scientific reports, 8(1), 15293. |
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