纳米集群形成和稳定基本研究:通过开发,然后应用五个比较标准,对常用的离子稳定剂进行排名
1Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
Journal of the American Chemical Society
|May 16, 2002
概括
本研究介绍了对过渡金属纳米集群稳定剂的排名方法,为Ir(0) 纳米集群寻找优于酸盐,聚烯酸盐和的多氧离子.
科学领域:
- 材料科学 材料科学 材料科学
- 纳米技术 纳米技术
- 无机化学 无机化学
背景情况:
- 过渡金属纳米集群在各种应用中至关重要.
- 现有的纳米集群稳定文献缺乏稳定剂的明确排名方法.
- 表面吸附的离子在纳米集群稳定中发挥着根本性的作用.
研究的目的:
- 开发和应用标准来对常见纳米集群稳定剂的形成和稳定能力进行排名.
- 为了建立一个定量基础,选择有效的离子转变金属纳米集群合成.
- 为了解决关于纳米集群稳定功效的文献中的混乱问题.
主要方法:
- 开发了五个不同的标准来评估纳米集群稳定剂.
- 建立了实验方法来评估代理对纳米集群形成与稳定性的影响.
- 将这些标准应用于四种常见的离子:多氧离子,酸盐,多酸盐和化物.
主要成果:
- 关于相对纳米团形成和稳定能力的第一个"阴离子系列"是为Ir(0) 的纳米团建立的.
- 确定的排名是:多氧 > 酸盐 > 多烯酸盐 ≈ 化物.
- 聚氧离子,特别是高电荷和基本的聚氧离子,成为优越的稳定剂.
结论:
- 开发的标准有效地将纳米集群形成与稳定效应分开.
- 聚氧离子代表了纳米集群稳定测试离子中的"黄金标准".
- 这项工作为未来开发改进的纳米集群稳定剂提供了关键的参考.
相关概念视频
Colloids
Children at play often make suspensions such as mixtures of mud and water, flour and water, or a suspension of solid pigments in water known as tempera paint. These suspensions are heterogeneous mixtures composed of relatively large particles that are visible to the naked eye or can be seen with a magnifying glass. They are cloudy, and the suspended particles settle out after mixing. On the other hand, a solution is a homogeneous mixture in which no settling occurs and in which the dissolved...
Anionic Chain-Growth Polymerization: Overview
The polymerization process that involves carbanion as an intermediate is called anionic polymerization. It is also a type of addition or chain-growth polymerization. Anionic polymerization gets initiated by a strong nucleophile such as an organolithium or a Grignard reagent. The most commonly used initiator for anionic polymerization is butyl lithium. Monomers involved in anionic polymerization must possess a vinyl group bonded to one or two electron-withdrawing groups. For instance,...
Colloidal precipitates
The high insolubility of some precipitates can result in an unfavorable relative supersaturation. This can lead to colloidal particles with a large surface-to-mass ratio, where adsorption is promoted. For instance, in the precipitation of silver chloride, silver ions are adsorbed on the surface of the colloidal particles, forming a primary layer. This layer attracts ions of opposite charge (such as nitrate ions), forming a diffuse secondary layer of adsorbed ions. This electric double layer...
Ion Exchange
Ion exchange chromatography separates charged molecules from a solution by reversibly exchanging them with mobile, or 'active', ions associated with the oppositely charged stationary phase. This method can be used to separate ions, soften and deionize water, and purify solutions. The polymers comprising the ion-exchange column are high-molecular-weight and chemically stable polymers, crosslinked to be porous and essentially insoluble. They are also functionalized with either acidic or basic...
Complexation Equilibria: Factors Influencing Stability of Complexes
In complexation reactions, metal cations are the electron pair acceptors, and the ligands are the electron pair donors. The stability of the metal complexes depends primarily on the complexing ability of the central metal ion and the nature of the ligands. Generally, the complexing ability of the metal ion depends on the size and charge of the ion. As the metal ion size increases, the stability of the metal complexes decreases, provided that the valency of the metal ion and the ligands remain...
The Colloidal State
The formation of a colloidal system is exemplified by an aqueous solution containing Cl− ions is introduced to another containing Ag+ ions, resulting in the precipitation of solid AgCl as extremely tiny crystals. Instead of settling out as a filterable precipitate, these crystals remain suspended in the liquid, showcasing a colloidal system.A colloidal system involves colloidal particles within the approximate range of 1 to 1000 nm in at least one dimension, dispersed in a medium called the...


