title: Adsorption kinetic process of thiol ligands on gold nanocrystals.
abstract: Understanding the kinetic mechanism during ligand adsorption on gold nanocrystals is important for designing and fine-tuning their properties and implications. Here, we report a kinetic study on the adsorption process of dodecanethiol ligands on Au nanocrystals of 3.3 nm by an in situ time-resolved X-ray absorption fine structure technique. A two-step process of dodecanethiol adsorption on Au NC surfaces is proposed based on the obtained ligand coverage, which shows a quick increase from 0 to 0.40 within the first 20 min, followed by a much slower increase to the limiting value of 0.94. In-depth analysis suggests that the first stage involves the quick adsorption of dodecanethiol to the corner and edge sites of Au NCs surfaces, leading to remarkable surface Au-Au bond length relaxation (from 2.79 to 2.81 Å) and pronounced gold-to-ligand charge transfer. The second step that corresponds to the much slower adsorption process to the surface facets could be described by the Langmuir kinetics equation with an adsorption rate constant of 0.0132 min(-1) and an initial coverage of 0.41, in good agreement with the initially preferable adsorption of thiols to the most favorable sites.
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, P.R. China. zhsun@ustc.edu.cn yaot@ustc.edu.cn.
authors.forename: Hao
authors.initials: H
authors.lastname: Cheng
authors.forename: Lina
authors.initials: L
authors.lastname: Yang
authors.forename: Yong
authors.initials: Y
authors.lastname: Jiang
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Huang
authors.forename: Zhihu
authors.initials: Z
authors.lastname: Sun
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Tiandou
authors.initials: T
authors.lastname: Hu
authors.forename: Zhiyun
authors.initials: Z
authors.lastname: Pan
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Pan
authors.forename: Tao
authors.initials: T
authors.lastname: Yao
authors.forename: Qing
authors.initials: Q
authors.lastname: Bian
authors.forename: Shiqiang
authors.initials: S
authors.lastname: Wei