Dissociative Chemisorption of Hydrazine on an Fe{211} Surface

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• 作者：Hayley L. McKay ; Stephen J. Jenkins ; David J. Wales
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：September 15, 2011
• 年：2011
• 卷：115
• 期：36
• 页码：17812-17828
• 全文大小：1541K
• 年卷期：v.115,no.36(September 15, 2011)
• ISSN：1932-7455

文摘

Density functional theory is employed to investigate the stepwise decomposition of hydrazine on Fe{211}. Local energy minima are described for N₂H_x (x = 0鈥?) intermediates, along with the transition states and pathways that connect them. We find that the dehydrogenation (N鈥揌 scission) and nitrogen decoupling (N鈥揘 scission) steps have activation energies in the range of 0.91 to 1.04 eV, with the exception of bond-breaking in NNH₂ (barrier of 0.52 eV) and for NNH (barrier of 0.55 eV). The reverse reactions of hydrogenation (N鈥揌 formation) and nitrogen coupling (N鈥揘 formation) have activation energies between 1.24 and 2.01 eV and 2.33 and 4.46 eV, respectively. Dehydrogenation and nitrogen decoupling are therefore generally competitive routes for hydrazine decomposition, with the dominant surface products at low-to-moderate temperatures being NH₂ moieties and N adatoms. Elevated temperatures should allow for the evolution of gas-phase N₂ and NH₃, the latter species being particularly favored under conditions of excess hydrogen.