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del Valle, M. A., Ramos, A. C., Diaz, F. R., & Gacitua, M. A. (2015). Electrosynthesis and Characterisation of Polymer Nanowires from Thiophene and its Oligomers. J. Braz. Chem. Soc., 26(11), 2313–2320.
Abstract: Validating methodology formerly reported, polythiophene electrosynthesised as nanowires from the monomer and some of its oligomers is now described. The work is conducted on a platinum electrode previously modified with a template that tunes the polymer growth inside the confined space of the pores. In addition, it was confirmed that the use of larger chain-length oligomers as starting unit helps to obtain more homogeneous wires, although its adhesion to the supporting substrate works against. Characterisation allows to verify the morphology and to confirm higher levels of doping/undoping of the nanostructures as compared to the corresponding bulky deposits, which points to improved macroscopic properties. It is demonstrated that this strategy allows obtaining nanowires of very small diameter, ranging from 2.8 to 4.0 nm; thus demonstrating that the use of this approach enables the direct obtainment of nanowires upon the electrode surface, with the obvious advantage that this implies.
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Gacitua, M. A., Gonzalez, B., Majone, M., & Aulenta, F. (2014). Boosting the electrocatalytic activity of Desulfovibrio paquesii biocathodes with magnetite nanoparticles. Int. J. Hydrog. Energy, 39(27), 14540–14545.
Abstract: The production of reduced value-added chemicals and fuels using microorganisms as cheap cathodic electrocatalysts is recently attracting considerable attention. A robust and sustainable production is, however, still greatly hampered by a poor understanding of electron transfer mechanisms to microorganisms and the lack of strategies to improve and manipulate thereof. Here, we investigated the use of electrically-conductive magnetite (Fe3O4) nanoparticles to improve the electrocatalytic activity of a H-2-producing Desulfovibrio paquesii biocathode. Microbial biocathodes supplemented with a suspension of nanoparticles displayed increased H-2 production rates and enhanced stability compared to unamended ones. Cyclic voltammetry confirmed that Faradaic currents involved in microbially-catalyzed H-2 evolution were enhanced by the addition of the nanoparticles. Possibly, nanoparticles improve the extracellular electron path to the microorganisms by creating composite networks comprising of mineral particles and microbial cells. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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Gacitua, M. A., Munoz, E., & Gonzalez, B. (2018). Bioelectrochemical sulphate reduction on batch reactors: Effect of inoculum-type and applied potential on sulphate consumption and pH. Bioelectrochemistry, 119, 26–32.
Abstract: Microbial electrolysis batch reactor systems were studied employing different conditions, paying attention on the effect that biocathode potential has on pH and system performance, with the overall aim to distinguish sulphate reduction from H-2 evolution. Inocula from pure strains (Desulfovibrio paquesii and Desulfobacter halotolerans) were compared to a natural source conditioned inoculum. The natural inoculum possess the potential for sulphate reduction on serum bottles experiments due to the activity of mutualistic bacteria (Sedimentibacter sp. and Bacteroides sp.) that assist sulphate-reducing bacterial cells (Desulfovibrio sp.) present in the consortium. Electrochemical batch reactors were monitored at two different potentials (graphite-bar cathodes poised at -900 and -400mV versus standard hydrogen electrode) in an attempt to isolate bioelectrochemical sulphate reduction from hydrogen evolution. At -900mV all inocula were able to reduce sulphate with the consortium demonstrating superior performance (SO42- consumption: 25.71 g m(-2) day(-1)), despite the high alkalinisation of the media. At -400mV only the pure Desulfobacter halotolerans inoculated system was able to reduce sulphate (SO42- consumption: 17.47 g m(-2) day(-1)) and, in this potential condition, pH elevation was less for all systems, confirming direct (or at least preferential) bioelectrochemical reduction of sulphate over H-2 production. (c) 2017 Elsevier B.V. All rights reserved.
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