How Well Does Pt(211) Represent Pt[n(111) 脳 (100)] Surfaces in Adsorption/Desorption?

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• 作者：Cansin Badan ; Marc T. M. Koper ; L.B.F. Juurlink
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：June 18, 2015
• 年：2015
• 卷：119
• 期：24
• 页码：13551-13560
• 全文大小：435K
• ISSN：1932-7455

文摘

We have investigated to what extent Pt(211) is representative for Pt[n(111) 脳 (100)] surfaces in adsorption/desorption behavior of water, hydrogen, and oxygen through temperature-programmed desorption. In contrast to surfaces with n > 3, H₂O adsorbs to Pt(211) in a crystalline fashion far below the usual crystallization temperature of amorphous solid water. For D₂, we find that desorption from (100) steps is independent of terrace length for n 鈮?3, but desorption from the neighboring (111) terraces varies. Larger terraces result in larger variations in binding energies as a consequence of decreasing proximity of adsorption sites to the step edge. For O₂, we observe enhanced dissociation on Pt(211) resulting in a much larger maximum O coverage than surfaces with n > 3. The TPD characteristics suggest formation of 1D PtO₂ structures, which are only formed for n = 3 with this (100) step type. Hence, Pt(211) can by no means be considered representative of Pt(111) terraces truncated by (100) steps. Our results stress that great caution is required when extrapolating results from theoretical studies based on this smallest unit cell containing the (100) step edge to catalysis by actual particles.