Atomically Monodisperse Palladium Nanoparticles: Size, Composition and Atomic Structure Studies

在金（Au）和银（Ag）纳米颗粒（数十至数百个原子的组装体）的情况下，在原子水平上操纵物质方面已经取得了重大进展。超小的小Au和Ag纳米颗粒是直径小于3 nm并且由小于500个原子组成的那些。这些纳米颗粒显示出明确的结构，并且可以在特定的有机分子（称为配体）被束缚在其表面时合成。然而，其他金属的纳米颗粒还没有通过这种策略得到很好的研究，如果没有配体，它们的结构可能很难确定。钯（Pd）纳米颗粒正在考虑用于各种实际应用，例如氢传感器和催化重要的化学反应，包括可再生能源中的几种感兴趣的应用。在这个项目中，密西西比大学的Amal Dass博士正在合成具有特定数量金属原子和保护配体的原子精确的Pd纳米颗粒。Dass博士正在将他的研究与外展活动相结合，包括高中生暑期研究项目、本科生研究项目和向当地和密西西比三角洲学校进行的科学示范。由化学部的大分子，超分子和纳米化学（MSN）计划资助，Dass博士正在合成原子单分散钯超小纳米颗粒。基质辅助激光解吸电离（MALDI）和电喷雾电离（ESI）质谱法用于确定金属原子的数量，硫醇配体，和整体化学组成。使用X射线晶体学检查这些纳米粒子的原子结构。使用电化学、光学光谱和电子显微镜进行进一步表征。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Significant progress has been made in the atomic level manipulation of matter in the case of gold (Au) and silver (Ag) nanoparticles, assemblies of tens to hundreds of atoms. Ultra-small small Au and Ag nanoparticles are those with diameters less than 3 nm and are composed of less than 500 atoms. These nanoparticles display well-defined structures and can be synthesized when specific organic molecules (known as ligands) are tethered to their surfaces. However, nanoparticles of other metals have not been well studied by this strategy and without ligands, their structures can be poorly defined. Palladium (Pd) nanoparticles are under consideration for a variety of practical applications, such as hydrogen sensors and to catalyze important chemical reactions including several of interest for applications in renewable energy. In this project, Dr. Amal Dass of the University of Mississippi is synthesizing atomically precise Pd nanoparticles with specific numbers of metal atoms and protecting ligands. Dr. Dass is integrating his research with outreach activities including a high school student summer research program, an undergraduate research program and science demonstrations to local and Mississippi Delta schools. Funded by the Macromolecular, Supramolecular and Nanochemistry (MSN) program of the Division of Chemistry, Dr. Dass is synthesizing atomically monodisperse palladium ultra-small nanoparticles. Matrix assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometry are used to determine the numbers of metal atoms, the thiolate ligands, and overall chemical composition. Atomic structures of these nanoparticles are examined using X-ray crystallography. Further characterization is conducted using electrochemistry, optical spectroscopy, and electron microscopy. The effect of ligands on the composition and structure of Pd nanoparticles is investigated and Pd alloy nanoparticles are prepared to tune chemical and physical properties.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.