Ammonia Dissociation on Pt{100}, Pt{111}, and Pt{211}: A Comparative Density Functional Theory Study

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• 作者：W. K. Offermans ; A. P. J. Jansen ; R. A. van Santen ; G. Novell-Leruth ; J. M. Ricart ; J. P&eacute ; rez-Ramí ; rez
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：November 29, 2007
• 年：2007
• 卷：111
• 期：47
• 页码：17551 - 17557
• 全文大小：419K
• 年卷期：v.111,no.47(November 29, 2007)
• ISSN：1932-7455

文摘

Density functional theory (DFT) calculations are performed to compare the dissociation of NH_x (x = 1-3)species on the Pt{100}, Pt{111}, and Pt{211} surface. Pt{211} is a stepped surface, and Pt{100} consists ofsquare arranged surface atoms. Both surfaces are less compact than Pt{111}. The question is addressed whetherthe Pt{100} and the Pt{211} surface promote the dissociation of NH_x species by lowering the activationbarriers with respect to Pt{111}. The NH dissociation reaction is promoted on Pt{100} but not on Pt{211}.The NH₂ dissociation reaction is neither promoted by Pt{100} nor Pt{211}. The dissociation of NH₃ is alsonot promoted and turns out to be a two-step reaction on the platinum surfaces. Atop-bonded NH₂ is intermediateand equally stable on the three surfaces. The nature of the transition states, which is late in the formation andearly in the rearrangement of this atop-bonded NH₂, makes the barriers almost independent of the surfacetopology. Because the reaction energies of the NH_x dissociation reactions do depend on the surface topologythe findings are unexpected, but they are consistent with an experimentally found moderate structure sensitivityof the ammonia decomposition on platinum.