谷氨覆盖黄金集群的取决于大小的兴奋状态行为及其光收获能力
Kevin G Stamplecoskie1, Prashant V Kamat
1Notre Dame Radiation Laboratory, Department of Chemistry and Biochemistry, University of Notre Dame Notre Dame, Indiana 46556, United States.
Journal of the American Chemical Society
|July 18, 2014
概括
黄金集群 黄金集群
科学领域:
- 纳米材料科学科学 纳米材料科学
- 摄影化学的使用.
- 催化剂是一种催化剂.
背景情况:
- 黄金集群表现出大小依赖的属性.
- 激发状态动力学和电子转移对于它们的功能至关重要.
- 连接体保护影响集群行为.
研究的目的:
- 为了研究黄金集群大小,激发状态属性和光催化活性之间的关系.
- 阐明金属 - 金属转换和体 - 金属电荷转移在集群放松中的作用.
- 为了确定最佳的黄金集群结构,用于光采集和光催化.
主要方法:
- 时间分辨率光谱学研究兴奋状态放松动态.
- 光催化实验涉及电子转移到甲基生物的实验.
- 激发状态寿命和光催化产量的相关性分析.
- 黄金集群大小和组成的特征.
主要成果:
- 黄金集群显示尺寸依赖的兴奋状态放松,较大的集群显示快速 (<1 ps) 和缓慢 (~200 ns) 衰变,分别归因于金属对金属和对金属的电荷转移.
- 快速放松的贡献随着较小的集群大小而减少.
- 光催化活性,通过电子转移到甲基维奥基因来测量,与联体到金属电荷转移激发状态的寿命有很强的相关性.
- 光催化还原产量随着集群大小的减少而增加 (Au25 < Au18 < Au15 < Au10-12).
结论:
- 黄金集群由于其长寿命的兴奋状态和电子传输能力,可以作为高效的采光天线.
- 较小的黄金星团,特别是Au18GSH14,由于它们有利的电子转移和可见光吸收的量子产量,显示出作为光敏化剂的巨大潜力.
- 调整集群大小是一个可行的策略,以优化光催化性能.
相关概念视频
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:15The Antenna Complex
Plants and other photosynthetic organisms comprise pigments capable of absorption of direct sunlight. These pigments are present in the reaction center - the main site of photochemical reactions as well as in the antenna complex. Under average light conditions, the rate at which reaction center pigments absorb light is far below the electron transport chain's capacity. As a result, the reaction center alone cannot provide enough energy to drive photosynthesis. The photosynthetic efficiency can...