Atomic-Scale Dynamics of Surface-Catalyzed Hydrogenation/Dehydrogenation: NH on Pt(111)

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• 作者：Zhu Liang ; Hyun Jin Yang ; Junepyo Oh ; Jaehoon Jung ; Yousoo Kim ; Michael Trenary
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：August 25, 2015
• 年：2015
• 卷：9
• 期：8
• 页码：8303-8311
• 全文大小：701K
• ISSN：1936-086X

文摘

Low-temperature scanning tunneling microscopy (LT-STM) was used to move hydrogen atoms and dissociate NH molecules on a Pt(111) surface covered with an ordered array of nitrogen atoms in a (2 脳 2) structure. The N-covered Pt(111) surface was prepared by ammonia oxydehydrogenation, which was achieved by annealing an ammonia鈥搊xygen overlayer to 400 K. Exposing the N-covered surface to H₂(g) forms H atoms and NH molecules. The NH molecules occupy face-centered cubic hollow sites, while the H atoms occupy atop sites. The STM tip was used to dissociate NH and to induce hopping of H atoms. Action spectra consisting of the reaction yield versus applied bias voltage were recorded for both processes, which revealed that they are vibrationally mediated. The threshold voltages for NH dissociation and H hopping were found to be 430 and 272 meV, corresponding to the excitation energy of the N鈥揌 stretching and the Pt鈥揌 stretching modes, respectively. Substituting H with D results in an isotopic shift of 鈭?10 and 鈭?4 meV for the threshold voltages for ND dissociation and D hopping, respectively. This further supports the conclusion that these processes are vibrationally mediated.