| Abstract
| - Density functional theory is employed to determine the reaction thermodynamics of a group of chemical andelectrochemical reactions chosen to investigate the dissolution of metal atoms from oxygen reduction reactioncatalysts in an acid medium. Once a set of thermodynamically allowed reactions is established, those reactionsare selected to investigate the relative stabilities of Pt atoms and of other transition metal atoms (Ir, Pd, Rh,Ni, and Co) toward the dissolution reactions. The dissolution reactions that are found thermodynamicallyfavorable are electrochemical and involve adsorbed oxygenated compounds that are intermediate species ofthe oxygen reduction reaction. Iridium is found to be the most stable among the various pure metals incomparison to Pt. Most of the metals alloyed with Pt cause a decrease of the Pt stability against dissolution,except for Ni, which does not affect it. On the other hand, the influence of Pt on the stability of the secondmetal in the alloy follows the same trend as in pure metal catalysts, with Ir being the most stable. When bothatoms in a PtM alloy are involved in dissolution reactions, alloyed Ir is also found more stable than Pt in agiven dissolution reaction, and the same behavior is found in alloyed Co for most of the reactions studied.
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