Andersson Klas J, Calle-Vallejo Federico, Rossmeisl Jan, Chorkendorff Ib
Center for Individual Nanoparticle Functionality (CINF), Department of Physics, NanoDTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
J Am Chem Soc. 2009 Feb 18;131(6):2404-7. doi: 10.1021/ja8089087.
Counterintuitive to expectations and all prior observations of adsorbate-induced surface segregation of the more reactive alloy component (the one forming the stronger bond with the adsorbate), we show that CO adsorption at elevated pressures and temperatures pulls the less reactive Cu to the surface of a CuPt near-surface alloy. The Cu surface segregation is driven by the formation of a stable self-organized CO/CuPt surface alloy structure and is rationalized in terms of the radically stronger Pt-CO bond when Cu is present in the first surface layer of Pt. The results, which are expected to apply to a range of coinage (Cu, Ag)/Pt-group bimetallic surface alloys, open up new possibilities in selective and dynamical engineering of alloy surfaces for catalysis.
与预期以及之前所有关于吸附质诱导更活泼合金组分（即与吸附质形成更强键的组分）表面偏析的观察结果相反，我们发现，在高压和高温下的CO吸附会将活性较低的Cu拉到CuPt近表面合金的表面。Cu的表面偏析是由稳定的自组织CO/CuPt表面合金结构的形成所驱动的，并且从当Cu存在于Pt的第一表面层时Pt-CO键显著更强的角度得到了合理的解释。这些结果有望应用于一系列造币用（Cu、Ag）/铂族双金属表面合金，为催化合金表面的选择性和动态工程开辟了新的可能性。
