Ultrasonic Spray Coating to optimize performance of Bio-Electrochemical Systems
Giacomo Spisni; Giulia Massaglia; Candido Fabrizio Pirri; Stefano Bianco; Marzia Quaglio.


In this work, we describe the optimization of carbon-based electrodes employed in Bio-Electrochemical Systems (BES) by the deposition on commercial carbon paper electrodes of nanostructured layers of poly(3,4-ethylene-dioxy-thiophene) poly(styrene-sulfonate) (PEDOT:PSS) via Ultrasonic Spray Coating (USC). This innovative application of USC allowed us to demon-strate that uniform and controlled depositions of PEDOT:PSS can be successfully obtained on car-bon-based electrodes. We characterized the morphology and verified the spatial uniformity of depositions via scanning electron microscopy and Raman spectroscopy. Electrochemical charac-terizations on fabricated electrodes demonstrated a more than two-fold increase in electrochemi-cal active surface area with respect to bare carbon paper. A lab-scale experiments on BES was performed selecting Microbial Fuel Cells (MFCs) as the reference devices. Devices featuring USC-deposited PEDOT:PSS electrodes showed a three-fold higher Energy recovery with respect to con-trol cells, reaching a maximum value of (13 ± 2) J·m−3. Furthermore, the optimal PEDOT:PSS con-centration for the MFCs improvement is in line with the values reported in the literature for other deposition methods. In conclusion, this work demonstrates that USC is a promising technique for application in BES.

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Keywords: nanostructured layer; ultrasonic spray coating; intrinsically conductive polymer; anode electrode; bioelectrochemical devices

2. Materials and Methods

2.1. Anodes Fabrication via Ultrasonic Spray Coating (USC)

We fabricated all anode electrodes by depositing a PEDOT:PSS nanostructured layer on bare carbon paper employing a Nadetech Ultrasonic Spray Coater (Nadetech Innovations, Spain). A great advantage of this technique is represented by the possibility to directly deposit the nanostructured layer onto carbon paper, ensuring a uniform deposition and a good adhesion, without the usage of other binders.