|Title||Steps on Pt stereodynamically filter sticking of O2|
|Publication Type||Journal Article|
|Year of Publication||2019|
|Authors||K. Cao, R. van Lent, A.W Kleyn, M. Kurahashi, L.BF Juurlink|
|Journal||Proceedings of the National Academy of Sciences|
Platinum is widely applied as an oxidation catalyst. The surfaces of metallic catalyst particles are generally composed of atomically flat planes connected by edges. In this paper, we unveil how Pt edges affect O2 sticking. Opposing types of behaviors are observed for high and low incident energies. The dependencies identify the mechanisms by which O2 molecules stick, which is the first step in the oxidation reactions.Low coordinated sites on catalytic surfaces often enhance reactivity, but the underlying dynamical processes are poorly understood. Using two independent approaches, we investigate the reactivity of O2 impinging onto platinum and resolve how step edges on (111) terraces enhance sticking. At low incident energy, the linear dependence on step density, independence of step type, and insensitivity to O2's molecular alignment show that trapping into a physisorbed state precedes molecular chemisorption and dissociation. At higher impact energies, direct molecular chemisorption occurs in parallel on steps and terraces. While terraces are insensitive to alignment of the molecule within the (111) plane, steps favor molecules impacting with their internuclear axis parallel to the edge. Stereodynamical filtering thus controls sticking and dissociation of O2 on Pt with a twofold role of steps.
|Alternate Title||Proc. Nat. Acad. Sci. USA|
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