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

在金（Au）和银（Ag）纳米粒子（由数十到数百个原子组成）的情况下，在物质的原子水平操纵方面取得了重大进展。超小金、银纳米粒子是指直径小于3nm，由小于500个原子组成的纳米粒子。这些纳米颗粒显示出明确的结构，并且当特定的有机分子（称为配体）拴在它们的表面时可以合成。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，没有配体，它们的结构可能很难定义。钯（Pd）纳米颗粒正在考虑各种实际应用，如氢传感器和催化重要的化学反应，包括一些可再生能源的应用。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。达斯博士正在将他的研究与拓展活动相结合，包括高中生暑期研究项目、本科生研究项目以及向当地和密西西比三角洲学校进行的科学示范。在化学系大分子、超分子和纳米化学（MSN）项目的资助下，达斯博士正在合成原子单分散的钯超小纳米颗粒。采用基质辅助激光解吸电离（MALDI）和电喷雾电离（ESI）质谱法测定金属原子数、硫酸盐配体和整体化学成分。这些纳米粒子的原子结构用x射线晶体学进行了检测。进一步的表征是使用电化学、光谱学和电子显微镜进行的。研究了配体对钯纳米粒子组成和结构的影响，制备了钯合金纳米粒子，以调整其化学和物理性质。该奖项反映了美国国家科学基金会的法定使命，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.