Nanostructured layer based on intrinsically conductive polymers for optimizing carbon electrodes' surface: Electrospray and Ultrasonic Spray Coating

Nowadays, Bio-Electrochemical System such as Microbial Fuel Cells (MFCs) and Microbial Electrolysis Cells (MECs) draw increasing attention for their potential application in sustainable energy production. Both systems leverage the electrogenic ability of selected biofilms, which consume chemical energy to produce electricity, in MFCs, or to promote hydrogen gas production, in MECs. In both MFCs and MECs, the anode electrode offers mechanical support and an electron sink for the biofilm. For this reason, it is crucial to optimize the electrode’s surface morphology and electrical properties, so to promote biofilm adhesion and proliferation, while minimizing electrical losses due to interfacial impedances. To this end, previous studies proposed the decoration of commercial carbon paper with the well-known conducting polymer Poly(3,4-ethylenedioxythiophene):poly-styrene sulfonate (PEDOT:PSS) (http://doi.org/10.1016/j.chemosphere.2020.125985). In addition, the surface decoration with Polyethylene oxide (PEO) demonstrated to promote biofilm proliferation (http://doi.org/10.3390/nano10030523). In this work, we focus on Electrospray and Ultrasonic Spray Coating as two promising and innovative fabrication techniques for the deposition of PEO and PEDOT:PSS solutions on commercial carbon paper. Electrospray offers the advantage of depositing nanoscale droplets with excellent uniformity on conductive substrates. For comparison, Ultrasonic Spray Coating also provides good deposition uniformity over large scale substrates. Employing electron microscopy, for both techniques we determined the deposition conditions providing the best uniformity of the electrodes’ surface morphology. In addition, we investigated the use of Raman spectroscopy to validate and map such spatial uniformity in a more quantitative manner. Moreover, electrochemical impedance spectroscopy and cyclic voltammetry demonstrated the improvements, given by electrodes’ surface decoration, in terms of conductivity and capacitive properties. As final stage, we are currently comparing in complete MFC devices the performance and stability of PEO and PEDOT:PSS decorated electrodes.