Effects of the environment on the performance of PEM nanocatalysts
P. B. Balbuena
University of South Carolina, US
Keywords: PEM Fuel cell
Understanding the mechanisms and intricacies of catalytic and electrocatalytic processes is one of the goals that must be achieved in order to optimize fuel cell performances.
Transition metal nanocatalysts have been used since the 60’s, however they are in most cases the result of poorly defined fabrication procedures. Nanocatalysts not only provide reaction rates enhanced with respect to those obtained from catalysis on extended surfaces, most importantly they may be suitable for alternative reaction paths that are available only because of the singular electronic characteristics of the nano-dimensions. Besides, the feature size of nano-scale systems allows a theory-guided and a controlled atomic manipulation that should enable the fabrication of nanosystems with very precise characteristics.
An important aspect of PEM carbon-supported transition metal nanocatalysts is that they are immersed in a proton-conductive hydrated polymeric membrane through which the reactants are able to reach the catalytic surface. Although quantum and classical molecular simulations are beginning to be used for the analysis and design of materials suitable for fuel cell catalysis and electrocatalysis, in many cases the additional complexity due to the effects of the environment surrounding the catalyst/reactant system is ignored. In this talk we will discuss our recent molecular simulations work addressing the temperature and pressure effects on the shape and structure of mono and bimetallic nanoclusters deposited on graphite, as well as the interactions of the hydrated polymer membrane with such structures. Moreover, we will discuss how these effects would modify the cathodic overpotential for the electroreduction of oxygen.
NSTI Nanotech 2003 Conference Technical Program Abstract