Authors: T.R. Mattsson and S.J. Paddison
Affilation: Sandia National Laboratories, United States
Pages: 471 - 473
Keywords: PEM fuel cell, ab-initio molecular dynamics, CH3OH, H2O-Pt interface
Among the engineering achievements, including a reduction in the overall cost of the system, necessary for Direct Methanol Fuel Cells (DMFC) to become a competitive alternative for both portable and stationary power applications, are improved catalysts. An important step towards improving existing solutions, in turn, is a fundamental, molecular based, understanding of the catalytic processes. Computer simulations, in particular calculations from first principles, have proven to provide key insights into gas-phase catalytic reactions. Density Functional Theory (DFT) stands out as the method of choice for this type of problems. With DFT, it is possible to describe molecular reactions as well as an extended metallic surface without assumptions about atomic interactions. DFT has therefore been used extensively, and successfully, for explaining properties of gas-phase reactions at surfaces. The situation in a DMFC is, on the other hand, significantly more complex since the water solution and the water/ Platinum interface will substantially influence the reaction kinetics. In this talk, we present first-principles molecular dynamics simulations of methanol near the Pt/water interface. Energies, bond lengths, bond angles and correlation functions during trajectories extending several nanoseconds will be reported. The dependences on distance from the interface as well as on the orientation of the methanol molecule relative to the surface will be investigated and compared to the corresponding quantities for the gas-phase reaction. T.R.M. acknowledges support from the Motorola/SNL computational materials CRADA. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000.