Université de Lyon, CNRS, Institut de Chimie de Lyon, Ecole normale, supérieure de Lyon, 15 Parvis Descartes, BP7000, F-69342 Lyon Cedex 07, France.
Phys Chem Chem Phys. 2012 Nov 28;14(44):15286-90. doi: 10.1039/c2cp43014b. Epub 2012 Oct 10.
The dissociation of water is a key elementary step in many processes. From density functional theory, we show on several transition metal surfaces (Ru, Co, Rh, Ir, Ni, Pd and Pt) that water prefers to chemisorb as a H-bonded dimer, one molecule being chemisorbed by the O atom, but the second one developing only a weak interaction with the surface. Counterintuitively, the molecule in the dimer that shows the smallest activation energy for O-H dissociation is the one interacting weakly with the surface. The H-bonded dimer provides a clear synergy for its chemisorption and assists the dissociation of the H-bond acceptor water molecule. Two different classes of O-H activation pathways are clearly identified with a linear activation energy-reaction energy relationship, of Brønstedt-Evans-Polanyi type.
水的离解是许多过程中的关键基元步骤。从密度泛函理论出发，我们在几种过渡金属表面（Ru、Co、Rh、Ir、Ni、Pd 和 Pt）上表明，水优先以氢键二聚体的形式化学吸附，其中一个分子通过 O 原子化学吸附，但第二个分子仅与表面发生微弱相互作用。出人意料的是，在二聚体中，O-H 离解的活化能最小的分子与表面的相互作用最弱。氢键二聚体为其化学吸附提供了明确的协同作用，并有助于氢键受体水分子的离解。通过 Brønsted-Evans-Polanyi 类型的线性活化能-反应能关系，明确地确定了两种不同的 O-H 活化途径。
