Ma Teng, Surnev Svetlozar, Netzer Falko P
College of Science, Shenyang Agricultural University, Shenyang 110168, China.
Surface and Interface Physics, Institute of Physics, Karl-Franzens University Graz, A-8010 Graz, Austria.
Materials (Basel). 2015 Aug 11;8(8):5205-5215. doi: 10.3390/ma8085205.
The growth morphology and structure of ceria nano-islands on a stepped Au(788) surface has been investigated by scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). Within the concept of physical vapor deposition, different kinetic routes have been employed to design ceria-Au inverse model catalysts with different ceria nanoparticle shapes and arrangements. A two-dimensional superlattice of ceria nano-islands with a relatively narrow size distribution (5 ± 2 nm²) has been generated on the Au(788) surface by the postoxidation method. This reflects the periodic anisotropy of the template surface and has been ascribed to the pinning of ceria clusters and thus nucleation on the fcc domains of the herringbone reconstruction on the Au terraces. In contrast, the reactive evaporation method yields ceria islands elongated in [01-1] direction, , parallel to the step edges, with high aspect ratios (~6). Diffusion along the Au step edges of ceria clusters and their limited step crossing in conjunction with a growth front perpendicular to the step edges is tentatively proposed to control the ceria growth under reactive evaporation conditions. Both deposition recipes generate two-dimensional islands of CeO₂(111)-type O-Ce-O single and double trilayer structures for submonolayer coverages.
通过扫描隧道显微镜（STM）和低能电子衍射（LEED）研究了台阶状Au(788)表面上二氧化铈纳米岛的生长形态和结构。在物理气相沉积的概念范围内，采用了不同的动力学途径来设计具有不同二氧化铈纳米颗粒形状和排列的二氧化铈-金反相模型催化剂。通过后氧化法在Au(788)表面生成了尺寸分布相对较窄（5±2 nm²）的二氧化铈纳米岛二维超晶格。这反映了模板表面的周期性各向异性，并归因于二氧化铈簇的钉扎以及因此在金台地人字纹重构的面心立方域上的成核。相比之下，反应蒸发法产生的二氧化铈岛在[01-1]方向上伸长，与台阶边缘平行，纵横比高（约6）。初步提出，二氧化铈簇沿着金台阶边缘的扩散及其有限的台阶穿越，再加上垂直于台阶边缘的生长前沿，控制了反应蒸发条件下二氧化铈的生长。两种沉积方法都生成了CeO₂(111)型O-Ce-O单双层和双层结构的二维岛，用于亚单层覆盖。
