Catalysis of ORR in nano-structured Mn oxides based-electrodes for microbial fuel cells

Title : Catalysis of ORR in nano-structured Mn oxides based-electrodes for microbial fuel cells

Abstract:

The microbial fuel cell (MFC) is a biotechnology that utilises bacteria to create clean and renewable electrical energy by oxidising organic substances in wastewater and represents a promising alternative for generating power. The performance of MFCs is currently limited by the cathode, and this problem is projected to remain for some time. Thus, cathode materials and their design are the most challenging aspects of an MFC. Previous research has determined that the oxygen reduction reaction (ORR) on the cathode is a limiting step for electricity production. The ORR rate is a major factor to be considered in the design of low-cost and high-efficiency MFCs. Platinum (Pt) is a highly active catalyst generally used to improve the ORR rate. However, catalyst poisoning of Pt-based cathodes are essential problems, which cause considerable kinetic losses in ORR, especially in the long-time operations. Despite higher power density of Pt in the polarization curve, poisoning of Pt cathode may occur by exposure to wastewater in long time operations of MFCs lead to the lower potential generation. For this reasons, low-cost non-Pt catalysts should be developed. Manganese dioxide has previously been studied as a highly chemical stable, eco-friendly and cost-effective alternative to Pt in fuel cells. In this work, a carbon cloth (CC) air cathode decorated by nano-structured MnO₂ was prepared using a voltametric method, in which CC acted as a support for the MnO₂ catalyst. After the electrodeposition, the prepared catalyst has been coupled with a mixture of activated carbon and carbon black (AC/CB) by a paint brush method. Linear sweep voltammetry (LSV), scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterise the prepared air-electrodes. The bio-activity of the MFCs equipped with the prepared MnO₂ air cathodes was evaluated: the influence of MnO₂ electrodeposition time on cathode performance was investigated.

Audience take-away:

• The audience will can use the techniques proposed in the present work to set an experimental procedure that can be used for the synthesis of nanostructured manganese oxide.
• The audience will can apply a defined procedure for the synthesis of new materials for energy application.
• This research can be used by other researchers both for energy applications and wastewater treatment, because it is a low-cost solution for the set-up of microbial fuel cells.
• This research will provide a practical solution to simplify the synthesis of cathode surfaces, as the process studied for obtaining the new materials can be easily scaled from mm² to cm² of electrode surface.

Biography:

Laura Mais is master graduate in Chemical Engineering in 2011 and PhD in Industrial Engineering in 2015; she got the assistant professor position in the field of “Chemical Plant design”. The research activities are focused on the field of electrochemical engineering applied to the study of processes for environmental remediation and energy conversion. Main topics have been electrochemical synthesis and characterization of semiconductor nanostructured materials (anodization for synthesis of TiO₂ nanotubes), electrochemical characterization of the deposition process of refractory metals. In particular, the study covers key aspects such as catalytic activity of electrode materials, identification of reaction mechanisms, and surface/solid interactions.