Innovative catalyst supports to address fuel cell stack durability

To successfully penetrate the automotive market, cost-efficient and durable fuel cell technologies are necessary to compete with existing mature technologies. Extensive automotive field tests have demonstrated that the membrane-electrode-assembly plays a crucial role in the overall lifetime of the fuel cell stack. Transient conditions are responsible for membrane electrode assembly performance loss: power (or voltage) cycling increases the rate of electrocatalyst surface area loss; start-up/shut-down induces membrane degradation and carbon corrosion. Carbon under Proton Exchange Membrane (PEM) fuel cell operating conditions is thermodynamically unstable and will be oxidized/corroded at potentials near the open circuit voltage of a fuel cell (about 1.0 V), with the oxidation rate increasing along with potential. It has been demonstrated that at start-up the lack of hydrogen at the anode is critical for carbon corrosion at the cathode. Carbon corrosion will eventually result in Pt particle agglomeration and loss of performance. The present study focuses on the development of new catalyst support materials, based on Nb-doped TiO2, as alternatives to conventional carbon supports in order to overcome the corrosion related issues. The present work investigates the effect of chemical composition and crystallinity of the newly developed materials on the electrical conductivity and stability. In the design of the new support particular attention was paid to the synergistic effect of the support with the supported metal nano-particle, aiming at promoting higher catalyst activity and stability. Copyright (c) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.