Institute of Surface Chemistry and Catalysis, Ulm University, 89069 Ulm, Germany.
Chemphyschem. 2012 Oct 8;13(14):3313-9. doi: 10.1002/cphc.201200294. Epub 2012 Jul 13.
We report on results of a detailed scanning tunnelling microscopy study on the formation, size and size distribution, and internal structure of small bimetallic PtRu clusters on a graphene monolayer film supported on a Ru(0001) substrate. These clusters, with sizes around ∼15 (Ru) or ∼40 (Pt) atoms per cluster at the lowest coverage, are interesting model systems for the catalytic behaviour of small metal PtRu particles, for example for application in electrocatalytic oxidation reactions. The clusters were generated by sequential deposition of the two metals at room temperature. The data reveal a distinct influence of the deposition sequence on the cluster formation process, with Ru pre-deposition followed by Pt deposition leading to predominantly bimetallic clusters, possibly with a core-shell-type structure, while the reverse sequence results in co-existent mono- and bimetallic clusters, where the latter are likely to intermix at the interface. The observations are related to the nucleation process of the respective metals on the templated surface, and the 2D growth behaviour of the two metals.
我们报告了在 Ru(0001) 衬底上支撑的石墨烯单层膜上形成的、尺寸和尺寸分布以及小双金属 PtRu 团簇的内部结构的详细扫描隧道显微镜研究结果。这些团簇在最低覆盖度下，每个团簇的尺寸约为 ∼15(Ru)或 ∼40(Pt)个原子，是小金属 PtRu 颗粒催化行为的有趣模型体系，例如在电催化氧化反应中的应用。这些团簇是通过在室温下顺序沉积两种金属而生成的。数据表明沉积顺序对团簇形成过程有明显影响，Ru 预沉积后再沉积 Pt 会导致主要形成双金属团簇，可能具有核壳型结构，而相反的顺序则会导致单金属和双金属团簇共存，后者可能在界面处混合。这些观察结果与模板表面上各自金属的成核过程以及两种金属的二维生长行为有关。
