Significance Statement
From previous research, it has been discovered that lattice constant varies with metallic cluster sizes. However, little or no study evaluated size dependency of lattice constant change of metal nanoclusters as a result of the inadequate handling of their cluster size.
Professor Toshihiro Kondo and colleagues studying the size dependent lattice constant change of self-assembled monolayer modified gold nanoclusters assembled on Au(111) surface using grazing incidence x-ray diffraction coupled with electrochemical treatments. The research work appeared recently in peer-reviewed journal, Electrochemical Communications.
The authors implemented this study with the aid of a grazing incidence x-ray diffraction after each electrochemical treatment which provided information on cluster sizes, lattice constants and charge densities.
Cyclic voltammograms of Au(111) electrode modified with gold nanoclusters based on poly (allylamine hydrochloride) confirmed the oxidative decomposition of thiol self-assembled monolayers as redox waves of ferrocene/ferrocenium Fc/Fc+ couple at a value of 0.35V decreased by repeat of potential cycles between 0 and 1.30V. Results also showed increase in oxidation and reduction current with the number of potential cycles with respect to formation and reduction of gold oxide.
Due to oxidative decomposition of self-assembled monolayers, the cluster size and lattice constant of gold nanoclusters decreased from 16Å and 4.19Å to 12Å and 4.01Å respectively, which led to an increase in charge density for reduction of gold oxide and decrease in charge density of ferrocene/ferrocenium couple.
With further oxidative decomposition of self-assembled monolayers, cluster size of gold nanoclusters increased to ca. 17Å with decrease in lattice constant to ca. 3.93Å as increase in charge reduction of gold oxide (at the 8th cycle) was also observed.
After the complete removal self-assembled monolayers, bare gold nanoclusters were seen. The cluster size and lattice constant increased to ca. 35Å and ca. 4.07Å respectively. There was still a further increase in charge reduction of gold oxide as that of ferrocene/ferrocenium couple became zero at the 12th cycle.
At the 50th cycle, cluster size of gold nanoclusters was ca. 40Å but lattice constant remained almost the same at around 4.08Å. Charge density for reduction of gold oxide also showed an increase up to the 30th cycle and 50th cycle. This results show that changes in size dependent lattice constant can only be observed when gold nanoclusters were approximately smaller than 35Å.
The results showed consistency with previous reports on relationship between cluster size and lattice constant of gold nanoclusters thereby proving its validity. This study expand our understanding on properties of nanoclusters in view of the crystal size and lattice constant which are very important in catalytic activity
Journal Reference
- Global Research Center for Environmental and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan.
- Graduate School of Humanities and Sciences, Ochanomizu University, Tokyo 112-8610, Japan.
- Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.
- Synchrotron X-ray Station at SPring-8, Research Network and Facility Service Division, National Institute for Materials Science (NIMS), Hyogo 679-5148, Japan.
- International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan.
Go To Electrochemistry Communications
Advances in Engineering Advances in Engineering features breaking research judged by Advances in Engineering advisory team to be of key importance in the Engineering field. Papers are selected from over 10,000 published each week from most peer reviewed journals.