Institute of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Key Laboratory of Mesoscopic Chemistry of MOE, Nanjing University, China.
Phys Chem Chem Phys. 2011 Jan 7;13(1):107-9. doi: 10.1039/c0cp01344g. Epub 2010 Nov 16.
Catalytic performances of alloy and surface alloy are sensitive to the surface structures and composition. In this paper we present an overall survey of the surface structure of Pd(111) covered with different amount of Zn using Monte Carlo simulations. We demonstrate that the composition of PdZn surface alloy is Zn coverage dependent: the surface concentration of Zn increases with the increase of the deposited Zn. At one or multi-layer of zinc deposited Pd(111), a multilayer 1 : 1 PdZn surface alloy will be formed. Surface alloy islands dominated by palladium are formed at submonolayer Zn coverage. At very low zinc coverage, small palladium ensembles of 3 to 5 Pd atoms exist preferentially on the Pd(111) surface. Our simulated results which are consistent with the pertinent experiments indicate that the unusual high-temperature desorption peak of formaldehyde observed experimentally has likely originated from the small surface ensembles induced by deposited Zn.
合金和表面合金的催化性能对表面结构和组成敏感。本文使用蒙特卡罗模拟对不同锌覆盖量的 Pd(111)表面结构进行了全面研究。结果表明，PdZn 表面合金的组成随锌覆盖量的增加而增加：表面锌浓度随沉积锌的增加而增加。在单层或多层锌覆盖的 Pd(111)上，将形成多层 1:1 PdZn 表面合金。在亚单层锌覆盖时，形成以钯为主的表面合金岛。在锌覆盖非常低的情况下，优先存在 3 到 5 个钯原子的小钯团簇在 Pd(111)表面上。我们的模拟结果与相关实验一致，表明实验中观察到的甲醛异常高温脱附峰很可能源于沉积锌诱导的小表面团簇。
