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

University Of Mississippi, University MS

Investigators

Abstract

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.