Role of Cathode Catalyst in Microbial Fuel Cell

Electrodes (cathode and anode) are the primary components of fuel cells. Oxidation of fuel at anode surface produces electrons and oxidized by-products. Subsequently, the electrons travel to cathode through an external circuit (Lu and Li 2012). At the cathode surface, appropriate terminal electron acceptors (TEA) are reduced by the incoming electrons and complete the cathodic half-cell reaction. The performance of a microbial fuel cell (MFC) strongly depends on the efficiency of the cathode. Generally, the efficacy of a cathode is determined from the reduction kinetics of the TEA (Rismani-Yazdi et al. 2008). The cathodic reduction is a surface electrochemical phenomenon. Thus, the surface of cathode plays a crucial role on the reduction kinetics of TEA. However, the widely used carbon-based cathodes show very poor reduction kinetics and limit the fuel cell performance (Rismani-Yazdi et al. 2008). This obstacle prompts the researchers to develop electrocatalysts for the enhanced cathodic reduction. The main purpose of the present chapter is to discuss different types of cathode catalysts and their influence on the bioelectricity generation in MFC. An effective cathode catalyst has to qualify several crucial requirements for practical applicability. First, it must be capable to deliver high intrinsic catalytic activity. Second, catalyst should show long term durability. Moreover, the electrocatalyst should have good electrical conductivity to minimize the resistive losses. In addition, the catalyst must be inexpensive, abundant and can easily be synthesized in large scale. In past, efforts have been made to find appropriate cathode catalysts. The findings are reviewed by several authors (Lu and Li 2012; Rismani-Yazdi et al. 2008; Kannan 2016; Liew et al. 2014).