First-principles study of decomposition of NH₃ on Ir(1 0 0)

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• 作者：Wuying Huang ; Wenzhen Lai ; Daiqian Xie
• 关键词：Density functional calculations ; Adsorption ; Decomposition ; Hydrogen ; Ammonia ; Transition metal surface
• 刊名：Surface Science
• 出版年：2008
• 出版时间：15 March 2008
• 年：2008
• 卷：602
• 期：6
• 页码：1288-1294
• 全文大小：357 K

文摘

The adsorption and dissociation of NH₃ on Ir(1 0 0) have been investigated using the periodic density functional calculations. The recombination desorption of N₂ has also been studied. The corresponding reaction energies, the structure of the transition states and the activation energies were determined. The calculated activation barrier for NH_x (x = 1–3) dehydrogenation is between 0.83 and 1.09 eV including the zero point energy correction. The NH₃ desorption energy of 0.95 eV is close to the NH₃ dehydrogenation barrier of 0.91 eV, which indicates that the desorption and dissociation of NH₃ on Ir(1 0 0) is very competitive, consistent with the recent experimental results. The N–H bond cleavage in NH₃ is found to be the rate limiting step. The activation energy for the recombinative desorption of N₂ is significantly lower than those for the NH_x dehydrogenation. Moreover, it was found that the zero point energy has a large contribution to the reaction energies and activation barriers.