N2 dissociation on Fe(110) and Fe/Ru(0001):: what is the role of steps?
N2 dissociation on Fe(110) and Fe/Ru(0001):: what is the role of steps?
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DOI：
10.1016/s0039-6028(01)01397-8
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发表时间：
2001-09-20
期刊：
影响因子：
1.9
通讯作者：
Chorkendorff, I
中科院分区：
文献类型：
--
作者：
Egeberg, RC;Dahl, S;Chorkendorff, I
在本文中，结果从实验研究的生长和反应性的Fe覆盖层Ru（0 0 0 1）结合密度泛函理论（DFT）计算的氮解离在紧密堆积的Fe表面。在此基础上，提出了N-2在Fe（1 1 0）和Fe/Ru（0 0 0 1）表面上的解离是由原子台阶/缺陷控制的.用密度泛函理论计算了N-2在Fe/ Ru（0 0 0 1）上解离的活化能比Fe（1 1 0）低36 kJ/mol.无论是在热和分子束实验中，我们没有观察到任何迹象，这种巨大的活动之间的差异铁覆盖层Ru（0 0 0 1）和Fe（1 1 0）。从热数据中，我们提取的N-2解离Fe/Ru（0 0 0 1）的表观活化势垒为28 +/- 3 kJ/mol，这是显着低于DFT计算的平台上（71 kJ/mol），但在同一表面上的一个台阶网站（39 kJ/mol）的计算结果吻合得很好。Fe/Ru（0 0 0 1）和Fe（1 1 0）上的低的热势垒和N-2活化之间的相似性强烈地表明，Fe（1 1 0）和Fe/Ru（0 0 0 1）上的反应均由台阶和/或缺陷主导。程序升温脱附曲线表明氮诱导的表面重建。(C)2001 Elsevier Science B. V.保留所有权利。
In this paper, results from an experimental study of the growth and reactivity of Fe overlayers on Ru(0 0 0 1) in combination with density functional theory (DFT) calculations of nitrogen dissociation on closed-packed Fe surfaces are presented. Based on these, it is suggested that the N-2 dissociation on Fe(1 1 0) and Fe/Ru(0 0 0 1) surfaces is dominated by atomic steps/defects. By DFT we calculate that the activation barrier for N-2 dissociation on Fe/ Ru(0 0 0 1) is 36 kJ/mol lower than for Fe(1 1 0). Neither in the thermal nor the molecular beam experiments do we observe any sign of this huge activity difference between Fe overlayers on Ru(0 0 0 1) and Fe(1 1 0). From thermal data we extract an apparent activation barrier for N-2 dissociation on Fe/Ru(0 0 0 1) of 28 +/- 3 kJ/mol which is significantly lower than that calculated by DFT (71 kJ/mol) on the terrace, but in good agreement with that calculated for a step site on the same surface (39 kJ/mol). The low thermal barrier and the similarity between N-2 activation on Fe/Ru(0 0 0 1) and Fe(1 1 0) strongly indicates that steps and/or defects dominate the reaction on both Fe(1 1 0) and Fe/Ru(0 0 0 1). Temperature programmed desorption curves indicated a nitrogen induced reconstruction of the surface. (C) 2001 Elsevier Science B.V. All rights reserved.