Simulation of OH– and oxygen transport in the air–cathode catalyst layer of microbial fuel cells

Abstract

The mass transfer of OH– and oxygen within an air–cathode is critical for the performance of microbial fuel cells (MFCs). Improving the understanding of this complex transportation mechanism could help guide the design of air-cathodes to enhance the power density of MFCs. Herein, a 2D-agglomerate model is developed to study OH– and O2 transfer, and electrochemical performance within an air–cathode MFC. The effects of key variables (binder volume fraction, and Pt/carbon mass ratio) on OH– and oxygen transport behavior have been investigated. Simulation results reveal that the OH– and oxygen concentrations within the catalyst layer are closely related to the catalyst layer structure. A lower volume fraction of Nafion® binder is beneficial to OH– and oxygen transfer, while the Pt/carbon mass ratio has complex effects on OH– and oxygen transfer and reactions. This work aims to improve our understanding of OH– and oxygen mass transfer and offers an effective approach to constructing high-performance air–cathode MFCs.