Sb在Au单晶电极上结构敏感吸附行为的比较

A Comparison on Structural Sensitive Adsorption of Sb on Au Single Crystalline Electrodes

本文研究比较Sb(III)在Au(111)和Au(100)电极上的不可逆吸附与还原和Sb的欠电位沉积行为及其相互影响.现场扫描隧道显微镜和循环伏安法测试结果表明,基底表面结构不仅影响阴离子的吸附行为和Sb的吸附结构,而且还影响其自身结构的稳定性.在Au(111)表面,致密无序膜的SbO+不可逆吸附层还原后基本保持原有的无序结构;而在Au(100)表面,由于SO42-的共吸附,不可逆吸附物种还原后形成(2×2)有序结构.在Au(111)表面上,Sb的欠电位沉积伴随显著的合金化,且因表面有序结构的破坏而形成沟道状二维结构;但对Au(100)表面,由于其晶格和尺寸与稳定的AuSb2合金之(100)面有较好的匹配性,使Au与Sb得以形成有序的表面化合物,从而避免了欠电位沉积过程中的表面合金化问题,进一步体现基底结构的敏感性和重要性.

We compare the behaviors of irreversible adsorption of Sb(III) and its reduction, underpotential deposition of Sbon Au(111) and Au(100) as well as mutual interactions of the processes. Based on in-situ scanning tunneling microscopic and cyclic voltammetric results, the substrate structure not only influence anion adsorptionbehavior and thus the Sb adsorption structure, but also the stability of its own structure. On Au(111) surface,the irreversibly adsorbed dense and disordered SbO^(+ )film structure remains after reduction of the film; while on Au(100)surface, due to the coadsorption of SO_4^(2-),an ordered(2×2)structure is formed after reduction.UPD of Sb on Au(111)is accompanied by significant surface alloying, which destroys the ordered structure of the Au (111) surface;while on Au(100)surface,the lattice type and lattice constantare in good match with that of the (100)plane of the stable AuSb2 alloy. Therefore the interaction between Au and Sb appears in the form of ordered surface compound, and surface alloying can be avoided during the process of UPD. The results further reflect the sensitivity as well as importance of the substrate structure.