Computational Studies of Detachment of Oxidized Pt from Pt Clusters

Birendra Adhikari, Chemical Engineering, Texas A&M University, 401 Stasney Street 501, College Station, TX 77840 and Perla Balbuena, Texas A&M Univ., College Station, TX 77843.

The properties of oxidized platinum ions undergoing a metal dissolution reaction from a platinum cluster surface in acid medium are studied using density functional theory. The process is relevant to low temperature, proton exchange membrane fuel cells. Model systems contain a few platinum atoms and a subsurface oxygen forming a Pt-O-Pt bridge. The behavior of oxidized platinum is further studied as a function of the number of platinum atoms in the cluster and adding water on the side of the Pt-O-Pt bridge. We analyze changes in Pt-O bond length, electrostatic (ESP) charges, Mulliken charges of the atoms, HOMO and LUMO energies and band gaps of the systems. Driving force for the detachment of platinum atoms is also studied