通过Pt@CoO黄皮纳米结构进行分子运输的IR光谱观测
Sunhee Kim1, Yadong Yin, A Paul Alivisatos
1Surface Science Center, Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA.
Journal of the American Chemical Society
|July 10, 2007
概括
在Pt@CoO纳米颗粒中,一氧化碳 (CO) 运输到 (Pt) 核中是通过通过氧化物 (CoO) 的活性表面扩散发生的,而不是外部Pt位点或气相运输.
科学领域:
- 纳米颗粒表面科学 纳米颗粒表面科学
- 材料化学 材料化学
- 催化剂是一种催化剂.
背景情况:
- 目前正在研究Pt@CoO纳米粒子的潜在催化应用.
- 了解CO与纳米粒子表面的相互作用对于优化催化过程至关重要.
- 之前的研究还没有完全阐明这些核心外结构中的二氧化碳传输机制.
研究的目的:
- 为了研究一氧化碳 (CO) 运输到 (Pt) 芯的Pt@CoO纳米颗粒的机制.
- 为了确定氧化物 (CoO) 在CO扩散过程中的作用.
- 为了确定涉及CO运输的特定物种.
主要方法:
- 福里埃变换红外光谱法 (FTIR) 用于监测CO物种.
- 对纳米粒子表面组成和结构的分析.
- 温度依赖的研究,以区分运输机制.
主要成果:
- 在纳米粒子表面上没有外部Pt位点.
- 通过通过CoO外激活的表面扩散,将CO转运到Pt核中.
- 一种不同的CO/CoO物种,在2147厘米-1下观察到,可在300K以下进行运输.
- 排除了气相运输作为主要机制.
结论:
- 在Pt@CoO纳米粒子中,CO运输到Pt核心是通过CoO外进行的.
- 一种CO/CoO中间体的活性表面扩散是主要的运输途径.
- 这些发现为表面化学和核心外纳米粒子的反应性提供了关键的见解.
相关概念视频
IR and UV–Vis Spectroscopy of Carboxylic Acids
In IR spectroscopy of carboxylic acids, the C=O bond shows a characteristic band between 1710 and 1760 cm⁻¹, and the O–H bond exhibits a broad band between 2500 and 3300 cm⁻¹.
However, the stretching absorptions for the C=O bond vary depending on the structure of carboxylic acids. The C=O bond of the free carboxylic acids shows a higher stretching frequency, 1760 cm−1, while H-bonded carboxylic acids (dimers) exhibit stretching absorptions at a lower frequency, 1710 cm−1. The C=O bond of the...
However, the stretching absorptions for the C=O bond vary depending on the structure of carboxylic acids. The C=O bond of the free carboxylic acids shows a higher stretching frequency, 1760 cm−1, while H-bonded carboxylic acids (dimers) exhibit stretching absorptions at a lower frequency, 1710 cm−1. The C=O bond of the...
UV–Vis Spectroscopy of Conjugated Systems
Organic compounds with conjugated double bonds show strong absorption features in the UV–visible region of the electromagnetic spectrum attributed to π → π* electronic excitations. Generally, a UV–vis absorption spectrum is recorded as a plot of absorbance vs wavelength. The wavelength of maximum absorbance, which manifests as a peak in the absorption spectrum, is denoted as λmax.
One of the factors influencing λmax is the extent of conjugation in the...
One of the factors influencing λmax is the extent of conjugation in the...
Molecular Spectroscopy: Absorption and Emission
Molecules possess discrete energy levels called quantum states. Unlike atoms, which have simpler energy levels, molecules possess additional rotational and vibrational energy levels. Each energy level is separated by an energy gap, with the gaps between adjacent electronic, vibrational, and rotational levels varying significantly. The three types of energy levels in a diatomic molecule are shown in Figure 1.
UV–Vis Spectroscopy: Molecular Electronic Transitions
In Ultraviolet–Visible (UV–Vis) spectroscopy, the absorption of electromagnetic radiation is used to probe the electronic structure of molecules. This technique provides insights into molecular electronic transitions, particularly the movement of electrons between different molecular orbitals. Radiation is absorbed if the energy of the electromagnetic radiation passing through the molecule is precisely equal to the energy difference between the excited and ground states. During this process,...
IR Spectroscopy: Molecular Vibration Overview
When Infrared (IR) radiation passes through a covalently bonded molecule, the bonds transition from lower to higher vibrational levels. The fundamental vibrational motions that result in infrared absorption can be classified as stretching or bending vibrations.
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
A covalently bonded heteronuclear diatomic molecule can be modeled as two vibrating masses connected by a spring. The vibrational frequency of the bond can be expressed using an equation derived from Hooke's law, which describes how the force applied to stretch or compress a spring is proportional to the displacement of the spring. In this case, the atoms behave like masses, and the bond acts like a spring.
According to Hooke's law, the vibrational frequency is directly proportional to the...
According to Hooke's law, the vibrational frequency is directly proportional to the...


