Assessing Free Radical Scavenging Activity of Various Cerium Materials for Proton Exchange Membrane Fuel Cells Using Fluorescence Spectroscopy Presentation Format

Abstract

Proton-exchange membrane fuel cells (PEMFCs) are an electrochemical energy conversion device that only has water vapor as an emission. During fuel cell operation, the PEM undergoes mechanical, thermal, and chemical degradation. The chemical degradation is attributed to reactive oxygen species (ROS) that are generated in situ through both chemical and electrochemical pathways during fuel cell operation. Hydrogen peroxide (H2O2) is a reactive oxygen species (ROS) and is often an intermediate formed in the presence of transition metal ion like Fe2+ or Fe3+. The free radical ROS mainly hydroxyl and hydroperoxyl radicals initiate oxidative degradation of both the PEM backbone and the side chains that contain ionic groups that are essential for ion conduction. In this study, various types of free radical scavenger (FRS) additives’ free radical scavenging activity are assessed using ex-situ and in-situ fluorescence spectroscopy(1, 2). Some of FRS materials studied are cerium oxide and doped ceria salts. The scavenging ability of the FRS materials were related to their physio-chemical properties – which were assessed by XPS, SEM, and dynamic light scattering (zetasizer). V. Prabhakaran, C. G. Arges and V. Ramani, Proceedings of the National Academy of Sciences of the United States of America, 109, 1029 (2012). V. Prabhakaran, C. G. Arges and V. Ramani, Phys Chem Chem Phys, 15, 18965 (2013).