Gu Zhihui, Balbuena Perla B
J Phys Chem A. 2006 Aug 17;110(32):9783-7. doi: 10.1021/jp063447o.
Density functional theory is employed to determine the reaction thermodynamics of a group of chemical and electrochemical reactions chosen to investigate the dissolution of metal atoms from oxygen reduction reaction catalysts in an acid medium. Once a set of thermodynamically allowed reactions is established, those reactions are 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 thermodynamically favorable are electrochemical and involve adsorbed oxygenated compounds that are intermediate species of the oxygen reduction reaction. Iridium is found to be the most stable among the various pure metals in comparison 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 second metal in the alloy follows the same trend as in pure metal catalysts, with Ir being the most stable. When both atoms in a PtM alloy are involved in dissolution reactions, alloyed Ir is also found more stable than Pt in a given dissolution reaction, and the same behavior is found in alloyed Co for most of the reactions studied.
采用密度泛函理论来确定一组化学和电化学反应的反应热力学，这些反应旨在研究酸性介质中氧还原反应催化剂上金属原子的溶解情况。一旦确定了一组热力学允许的反应，就选择这些反应来研究铂原子以及其他过渡金属原子（铱、钯、铑、镍和钴）相对于溶解反应的相对稳定性。发现热力学上有利的溶解反应是电化学的，且涉及作为氧还原反应中间物种的吸附氧化化合物。与铂相比，铱在各种纯金属中是最稳定的。除了不影响铂稳定性的镍之外，与铂合金化的大多数金属都会导致铂对溶解的稳定性降低。另一方面，铂对合金中第二种金属稳定性的影响与纯金属催化剂中的趋势相同，铱是最稳定的。当铂 - 金属合金中的两个原子都参与溶解反应时，在给定的溶解反应中，合金化的铱也比铂更稳定，并且在所研究的大多数反应中，合金化的钴也表现出相同的行为。
