Methanol-tolerant cathode electrode structure composed of heterogeneous composites to overcome methanol crossover effects for direct methanol fuel cell

Abstract

A methanol-tolerant cathode electrode composed of heterogeneous composites was developed to overcome CO poisoning and large O(2) mass transfer overpotential generated by methanol crossover as well as the limitation of a single alloy catalyst with methanol-tolerance in direct methanol fuel cells (DMFCs). Two additives, PtRu black and PTFE particles, were well distributed in the Pt/C matrix of the cathode electrode, and had significant effects upon open circuit voltage (OCV) and performance. A small amount of PtRu black protected the Pt surface during the oxygen reduction reaction (ORR) by decreasing CO poisoning. In addition, hydrophobic PTFE particles reduced the O(2) mass transfer overpotential induced by water and permeated methanol in the cathode. Despite only 0.5 mg cm(-2) of metal catalysts in the cathode, the membrane electrode assembly (MEA) with 3 M methanol showed high performance (0.117 W cm(-2)), which was larger than that of the traditional MEA (0.067 W cm(-2)). Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.